Bug Summary

File:lib/Analysis/ScalarEvolution.cpp
Warning:line 9979, column 15
Value stored to 'MaxBECount' during its initialization is never read

Annotated Source Code

1//===- ScalarEvolution.cpp - Scalar Evolution Analysis --------------------===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file contains the implementation of the scalar evolution analysis
11// engine, which is used primarily to analyze expressions involving induction
12// variables in loops.
13//
14// There are several aspects to this library. First is the representation of
15// scalar expressions, which are represented as subclasses of the SCEV class.
16// These classes are used to represent certain types of subexpressions that we
17// can handle. We only create one SCEV of a particular shape, so
18// pointer-comparisons for equality are legal.
19//
20// One important aspect of the SCEV objects is that they are never cyclic, even
21// if there is a cycle in the dataflow for an expression (ie, a PHI node). If
22// the PHI node is one of the idioms that we can represent (e.g., a polynomial
23// recurrence) then we represent it directly as a recurrence node, otherwise we
24// represent it as a SCEVUnknown node.
25//
26// In addition to being able to represent expressions of various types, we also
27// have folders that are used to build the *canonical* representation for a
28// particular expression. These folders are capable of using a variety of
29// rewrite rules to simplify the expressions.
30//
31// Once the folders are defined, we can implement the more interesting
32// higher-level code, such as the code that recognizes PHI nodes of various
33// types, computes the execution count of a loop, etc.
34//
35// TODO: We should use these routines and value representations to implement
36// dependence analysis!
37//
38//===----------------------------------------------------------------------===//
39//
40// There are several good references for the techniques used in this analysis.
41//
42// Chains of recurrences -- a method to expedite the evaluation
43// of closed-form functions
44// Olaf Bachmann, Paul S. Wang, Eugene V. Zima
45//
46// On computational properties of chains of recurrences
47// Eugene V. Zima
48//
49// Symbolic Evaluation of Chains of Recurrences for Loop Optimization
50// Robert A. van Engelen
51//
52// Efficient Symbolic Analysis for Optimizing Compilers
53// Robert A. van Engelen
54//
55// Using the chains of recurrences algebra for data dependence testing and
56// induction variable substitution
57// MS Thesis, Johnie Birch
58//
59//===----------------------------------------------------------------------===//
60
61#include "llvm/Analysis/ScalarEvolution.h"
62#include "llvm/ADT/APInt.h"
63#include "llvm/ADT/ArrayRef.h"
64#include "llvm/ADT/DenseMap.h"
65#include "llvm/ADT/DepthFirstIterator.h"
66#include "llvm/ADT/FoldingSet.h"
67#include "llvm/ADT/None.h"
68#include "llvm/ADT/Optional.h"
69#include "llvm/ADT/STLExtras.h"
70#include "llvm/ADT/ScopeExit.h"
71#include "llvm/ADT/Sequence.h"
72#include "llvm/ADT/SetVector.h"
73#include "llvm/ADT/SmallPtrSet.h"
74#include "llvm/ADT/SmallSet.h"
75#include "llvm/ADT/SmallVector.h"
76#include "llvm/ADT/Statistic.h"
77#include "llvm/ADT/StringRef.h"
78#include "llvm/Analysis/AssumptionCache.h"
79#include "llvm/Analysis/ConstantFolding.h"
80#include "llvm/Analysis/InstructionSimplify.h"
81#include "llvm/Analysis/LoopInfo.h"
82#include "llvm/Analysis/ScalarEvolutionExpressions.h"
83#include "llvm/Analysis/TargetLibraryInfo.h"
84#include "llvm/Analysis/ValueTracking.h"
85#include "llvm/IR/Argument.h"
86#include "llvm/IR/BasicBlock.h"
87#include "llvm/IR/CFG.h"
88#include "llvm/IR/CallSite.h"
89#include "llvm/IR/Constant.h"
90#include "llvm/IR/ConstantRange.h"
91#include "llvm/IR/Constants.h"
92#include "llvm/IR/DataLayout.h"
93#include "llvm/IR/DerivedTypes.h"
94#include "llvm/IR/Dominators.h"
95#include "llvm/IR/Function.h"
96#include "llvm/IR/GlobalAlias.h"
97#include "llvm/IR/GlobalValue.h"
98#include "llvm/IR/GlobalVariable.h"
99#include "llvm/IR/InstIterator.h"
100#include "llvm/IR/InstrTypes.h"
101#include "llvm/IR/Instruction.h"
102#include "llvm/IR/Instructions.h"
103#include "llvm/IR/IntrinsicInst.h"
104#include "llvm/IR/Intrinsics.h"
105#include "llvm/IR/LLVMContext.h"
106#include "llvm/IR/Metadata.h"
107#include "llvm/IR/Operator.h"
108#include "llvm/IR/PatternMatch.h"
109#include "llvm/IR/Type.h"
110#include "llvm/IR/Use.h"
111#include "llvm/IR/User.h"
112#include "llvm/IR/Value.h"
113#include "llvm/Pass.h"
114#include "llvm/Support/Casting.h"
115#include "llvm/Support/CommandLine.h"
116#include "llvm/Support/Compiler.h"
117#include "llvm/Support/Debug.h"
118#include "llvm/Support/ErrorHandling.h"
119#include "llvm/Support/KnownBits.h"
120#include "llvm/Support/SaveAndRestore.h"
121#include "llvm/Support/raw_ostream.h"
122#include <algorithm>
123#include <cassert>
124#include <climits>
125#include <cstddef>
126#include <cstdint>
127#include <cstdlib>
128#include <map>
129#include <memory>
130#include <tuple>
131#include <utility>
132#include <vector>
133
134using namespace llvm;
135
136#define DEBUG_TYPE"scalar-evolution" "scalar-evolution"
137
138STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
, {0}, false}
139 "Number of trip counts computed with array length")static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
, {0}, false}
;
140STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
, {0}, false}
141 "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
, {0}, false}
;
142STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
, {0}, false}
143 "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
, {0}, false}
;
144STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
, {0}, false}
145 "Number of loops with trip counts computed by force")static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
, {0}, false}
;
146
147static cl::opt<unsigned>
148MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
149 cl::desc("Maximum number of iterations SCEV will "
150 "symbolically execute a constant "
151 "derived loop"),
152 cl::init(100));
153
154// FIXME: Enable this with EXPENSIVE_CHECKS when the test suite is clean.
155static cl::opt<bool>
156VerifySCEV("verify-scev",
157 cl::desc("Verify ScalarEvolution's backedge taken counts (slow)"));
158static cl::opt<bool>
159 VerifySCEVMap("verify-scev-maps",
160 cl::desc("Verify no dangling value in ScalarEvolution's "
161 "ExprValueMap (slow)"));
162
163static cl::opt<unsigned> MulOpsInlineThreshold(
164 "scev-mulops-inline-threshold", cl::Hidden,
165 cl::desc("Threshold for inlining multiplication operands into a SCEV"),
166 cl::init(32));
167
168static cl::opt<unsigned> AddOpsInlineThreshold(
169 "scev-addops-inline-threshold", cl::Hidden,
170 cl::desc("Threshold for inlining addition operands into a SCEV"),
171 cl::init(500));
172
173static cl::opt<unsigned> MaxSCEVCompareDepth(
174 "scalar-evolution-max-scev-compare-depth", cl::Hidden,
175 cl::desc("Maximum depth of recursive SCEV complexity comparisons"),
176 cl::init(32));
177
178static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth(
179 "scalar-evolution-max-scev-operations-implication-depth", cl::Hidden,
180 cl::desc("Maximum depth of recursive SCEV operations implication analysis"),
181 cl::init(2));
182
183static cl::opt<unsigned> MaxValueCompareDepth(
184 "scalar-evolution-max-value-compare-depth", cl::Hidden,
185 cl::desc("Maximum depth of recursive value complexity comparisons"),
186 cl::init(2));
187
188static cl::opt<unsigned>
189 MaxArithDepth("scalar-evolution-max-arith-depth", cl::Hidden,
190 cl::desc("Maximum depth of recursive arithmetics"),
191 cl::init(32));
192
193static cl::opt<unsigned> MaxConstantEvolvingDepth(
194 "scalar-evolution-max-constant-evolving-depth", cl::Hidden,
195 cl::desc("Maximum depth of recursive constant evolving"), cl::init(32));
196
197static cl::opt<unsigned>
198 MaxExtDepth("scalar-evolution-max-ext-depth", cl::Hidden,
199 cl::desc("Maximum depth of recursive SExt/ZExt"),
200 cl::init(8));
201
202static cl::opt<unsigned>
203 MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden,
204 cl::desc("Max coefficients in AddRec during evolving"),
205 cl::init(16));
206
207//===----------------------------------------------------------------------===//
208// SCEV class definitions
209//===----------------------------------------------------------------------===//
210
211//===----------------------------------------------------------------------===//
212// Implementation of the SCEV class.
213//
214
215#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
216LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const {
217 print(dbgs());
218 dbgs() << '\n';
219}
220#endif
221
222void SCEV::print(raw_ostream &OS) const {
223 switch (static_cast<SCEVTypes>(getSCEVType())) {
224 case scConstant:
225 cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false);
226 return;
227 case scTruncate: {
228 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this);
229 const SCEV *Op = Trunc->getOperand();
230 OS << "(trunc " << *Op->getType() << " " << *Op << " to "
231 << *Trunc->getType() << ")";
232 return;
233 }
234 case scZeroExtend: {
235 const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this);
236 const SCEV *Op = ZExt->getOperand();
237 OS << "(zext " << *Op->getType() << " " << *Op << " to "
238 << *ZExt->getType() << ")";
239 return;
240 }
241 case scSignExtend: {
242 const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this);
243 const SCEV *Op = SExt->getOperand();
244 OS << "(sext " << *Op->getType() << " " << *Op << " to "
245 << *SExt->getType() << ")";
246 return;
247 }
248 case scAddRecExpr: {
249 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this);
250 OS << "{" << *AR->getOperand(0);
251 for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i)
252 OS << ",+," << *AR->getOperand(i);
253 OS << "}<";
254 if (AR->hasNoUnsignedWrap())
255 OS << "nuw><";
256 if (AR->hasNoSignedWrap())
257 OS << "nsw><";
258 if (AR->hasNoSelfWrap() &&
259 !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW)))
260 OS << "nw><";
261 AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false);
262 OS << ">";
263 return;
264 }
265 case scAddExpr:
266 case scMulExpr:
267 case scUMaxExpr:
268 case scSMaxExpr: {
269 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this);
270 const char *OpStr = nullptr;
271 switch (NAry->getSCEVType()) {
272 case scAddExpr: OpStr = " + "; break;
273 case scMulExpr: OpStr = " * "; break;
274 case scUMaxExpr: OpStr = " umax "; break;
275 case scSMaxExpr: OpStr = " smax "; break;
276 }
277 OS << "(";
278 for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
279 I != E; ++I) {
280 OS << **I;
281 if (std::next(I) != E)
282 OS << OpStr;
283 }
284 OS << ")";
285 switch (NAry->getSCEVType()) {
286 case scAddExpr:
287 case scMulExpr:
288 if (NAry->hasNoUnsignedWrap())
289 OS << "<nuw>";
290 if (NAry->hasNoSignedWrap())
291 OS << "<nsw>";
292 }
293 return;
294 }
295 case scUDivExpr: {
296 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this);
297 OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")";
298 return;
299 }
300 case scUnknown: {
301 const SCEVUnknown *U = cast<SCEVUnknown>(this);
302 Type *AllocTy;
303 if (U->isSizeOf(AllocTy)) {
304 OS << "sizeof(" << *AllocTy << ")";
305 return;
306 }
307 if (U->isAlignOf(AllocTy)) {
308 OS << "alignof(" << *AllocTy << ")";
309 return;
310 }
311
312 Type *CTy;
313 Constant *FieldNo;
314 if (U->isOffsetOf(CTy, FieldNo)) {
315 OS << "offsetof(" << *CTy << ", ";
316 FieldNo->printAsOperand(OS, false);
317 OS << ")";
318 return;
319 }
320
321 // Otherwise just print it normally.
322 U->getValue()->printAsOperand(OS, false);
323 return;
324 }
325 case scCouldNotCompute:
326 OS << "***COULDNOTCOMPUTE***";
327 return;
328 }
329 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 329)
;
330}
331
332Type *SCEV::getType() const {
333 switch (static_cast<SCEVTypes>(getSCEVType())) {
334 case scConstant:
335 return cast<SCEVConstant>(this)->getType();
336 case scTruncate:
337 case scZeroExtend:
338 case scSignExtend:
339 return cast<SCEVCastExpr>(this)->getType();
340 case scAddRecExpr:
341 case scMulExpr:
342 case scUMaxExpr:
343 case scSMaxExpr:
344 return cast<SCEVNAryExpr>(this)->getType();
345 case scAddExpr:
346 return cast<SCEVAddExpr>(this)->getType();
347 case scUDivExpr:
348 return cast<SCEVUDivExpr>(this)->getType();
349 case scUnknown:
350 return cast<SCEVUnknown>(this)->getType();
351 case scCouldNotCompute:
352 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 352)
;
353 }
354 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 354)
;
355}
356
357bool SCEV::isZero() const {
358 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
359 return SC->getValue()->isZero();
360 return false;
361}
362
363bool SCEV::isOne() const {
364 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
365 return SC->getValue()->isOne();
366 return false;
367}
368
369bool SCEV::isAllOnesValue() const {
370 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
371 return SC->getValue()->isMinusOne();
372 return false;
373}
374
375bool SCEV::isNonConstantNegative() const {
376 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this);
377 if (!Mul) return false;
378
379 // If there is a constant factor, it will be first.
380 const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
381 if (!SC) return false;
382
383 // Return true if the value is negative, this matches things like (-42 * V).
384 return SC->getAPInt().isNegative();
385}
386
387SCEVCouldNotCompute::SCEVCouldNotCompute() :
388 SCEV(FoldingSetNodeIDRef(), scCouldNotCompute) {}
389
390bool SCEVCouldNotCompute::classof(const SCEV *S) {
391 return S->getSCEVType() == scCouldNotCompute;
392}
393
394const SCEV *ScalarEvolution::getConstant(ConstantInt *V) {
395 FoldingSetNodeID ID;
396 ID.AddInteger(scConstant);
397 ID.AddPointer(V);
398 void *IP = nullptr;
399 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
400 SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V);
401 UniqueSCEVs.InsertNode(S, IP);
402 return S;
403}
404
405const SCEV *ScalarEvolution::getConstant(const APInt &Val) {
406 return getConstant(ConstantInt::get(getContext(), Val));
407}
408
409const SCEV *
410ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) {
411 IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
412 return getConstant(ConstantInt::get(ITy, V, isSigned));
413}
414
415SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID,
416 unsigned SCEVTy, const SCEV *op, Type *ty)
417 : SCEV(ID, SCEVTy), Op(op), Ty(ty) {}
418
419SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
420 const SCEV *op, Type *ty)
421 : SCEVCastExpr(ID, scTruncate, op, ty) {
422 assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 424, __PRETTY_FUNCTION__))
423 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 424, __PRETTY_FUNCTION__))
424 "Cannot truncate non-integer value!")(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 424, __PRETTY_FUNCTION__))
;
425}
426
427SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
428 const SCEV *op, Type *ty)
429 : SCEVCastExpr(ID, scZeroExtend, op, ty) {
430 assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot zero extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 432, __PRETTY_FUNCTION__))
431 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot zero extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 432, __PRETTY_FUNCTION__))
432 "Cannot zero extend non-integer value!")(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot zero extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 432, __PRETTY_FUNCTION__))
;
433}
434
435SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
436 const SCEV *op, Type *ty)
437 : SCEVCastExpr(ID, scSignExtend, op, ty) {
438 assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot sign extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 440, __PRETTY_FUNCTION__))
439 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot sign extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 440, __PRETTY_FUNCTION__))
440 "Cannot sign extend non-integer value!")(((Op->getType()->isIntegerTy() || Op->getType()->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot sign extend non-integer value!") ? static_cast
<void> (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 440, __PRETTY_FUNCTION__))
;
441}
442
443void SCEVUnknown::deleted() {
444 // Clear this SCEVUnknown from various maps.
445 SE->forgetMemoizedResults(this);
446
447 // Remove this SCEVUnknown from the uniquing map.
448 SE->UniqueSCEVs.RemoveNode(this);
449
450 // Release the value.
451 setValPtr(nullptr);
452}
453
454void SCEVUnknown::allUsesReplacedWith(Value *New) {
455 // Remove this SCEVUnknown from the uniquing map.
456 SE->UniqueSCEVs.RemoveNode(this);
457
458 // Update this SCEVUnknown to point to the new value. This is needed
459 // because there may still be outstanding SCEVs which still point to
460 // this SCEVUnknown.
461 setValPtr(New);
462}
463
464bool SCEVUnknown::isSizeOf(Type *&AllocTy) const {
465 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
466 if (VCE->getOpcode() == Instruction::PtrToInt)
467 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
468 if (CE->getOpcode() == Instruction::GetElementPtr &&
469 CE->getOperand(0)->isNullValue() &&
470 CE->getNumOperands() == 2)
471 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1)))
472 if (CI->isOne()) {
473 AllocTy = cast<PointerType>(CE->getOperand(0)->getType())
474 ->getElementType();
475 return true;
476 }
477
478 return false;
479}
480
481bool SCEVUnknown::isAlignOf(Type *&AllocTy) const {
482 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
483 if (VCE->getOpcode() == Instruction::PtrToInt)
484 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
485 if (CE->getOpcode() == Instruction::GetElementPtr &&
486 CE->getOperand(0)->isNullValue()) {
487 Type *Ty =
488 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
489 if (StructType *STy = dyn_cast<StructType>(Ty))
490 if (!STy->isPacked() &&
491 CE->getNumOperands() == 3 &&
492 CE->getOperand(1)->isNullValue()) {
493 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2)))
494 if (CI->isOne() &&
495 STy->getNumElements() == 2 &&
496 STy->getElementType(0)->isIntegerTy(1)) {
497 AllocTy = STy->getElementType(1);
498 return true;
499 }
500 }
501 }
502
503 return false;
504}
505
506bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
507 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
508 if (VCE->getOpcode() == Instruction::PtrToInt)
509 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
510 if (CE->getOpcode() == Instruction::GetElementPtr &&
511 CE->getNumOperands() == 3 &&
512 CE->getOperand(0)->isNullValue() &&
513 CE->getOperand(1)->isNullValue()) {
514 Type *Ty =
515 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
516 // Ignore vector types here so that ScalarEvolutionExpander doesn't
517 // emit getelementptrs that index into vectors.
518 if (Ty->isStructTy() || Ty->isArrayTy()) {
519 CTy = Ty;
520 FieldNo = CE->getOperand(2);
521 return true;
522 }
523 }
524
525 return false;
526}
527
528//===----------------------------------------------------------------------===//
529// SCEV Utilities
530//===----------------------------------------------------------------------===//
531
532/// Compare the two values \p LV and \p RV in terms of their "complexity" where
533/// "complexity" is a partial (and somewhat ad-hoc) relation used to order
534/// operands in SCEV expressions. \p EqCache is a set of pairs of values that
535/// have been previously deemed to be "equally complex" by this routine. It is
536/// intended to avoid exponential time complexity in cases like:
537///
538/// %a = f(%x, %y)
539/// %b = f(%a, %a)
540/// %c = f(%b, %b)
541///
542/// %d = f(%x, %y)
543/// %e = f(%d, %d)
544/// %f = f(%e, %e)
545///
546/// CompareValueComplexity(%f, %c)
547///
548/// Since we do not continue running this routine on expression trees once we
549/// have seen unequal values, there is no need to track them in the cache.
550static int
551CompareValueComplexity(SmallSet<std::pair<Value *, Value *>, 8> &EqCache,
552 const LoopInfo *const LI, Value *LV, Value *RV,
553 unsigned Depth) {
554 if (Depth > MaxValueCompareDepth || EqCache.count({LV, RV}))
555 return 0;
556
557 // Order pointer values after integer values. This helps SCEVExpander form
558 // GEPs.
559 bool LIsPointer = LV->getType()->isPointerTy(),
560 RIsPointer = RV->getType()->isPointerTy();
561 if (LIsPointer != RIsPointer)
562 return (int)LIsPointer - (int)RIsPointer;
563
564 // Compare getValueID values.
565 unsigned LID = LV->getValueID(), RID = RV->getValueID();
566 if (LID != RID)
567 return (int)LID - (int)RID;
568
569 // Sort arguments by their position.
570 if (const auto *LA = dyn_cast<Argument>(LV)) {
571 const auto *RA = cast<Argument>(RV);
572 unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo();
573 return (int)LArgNo - (int)RArgNo;
574 }
575
576 if (const auto *LGV = dyn_cast<GlobalValue>(LV)) {
577 const auto *RGV = cast<GlobalValue>(RV);
578
579 const auto IsGVNameSemantic = [&](const GlobalValue *GV) {
580 auto LT = GV->getLinkage();
581 return !(GlobalValue::isPrivateLinkage(LT) ||
582 GlobalValue::isInternalLinkage(LT));
583 };
584
585 // Use the names to distinguish the two values, but only if the
586 // names are semantically important.
587 if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV))
588 return LGV->getName().compare(RGV->getName());
589 }
590
591 // For instructions, compare their loop depth, and their operand count. This
592 // is pretty loose.
593 if (const auto *LInst = dyn_cast<Instruction>(LV)) {
594 const auto *RInst = cast<Instruction>(RV);
595
596 // Compare loop depths.
597 const BasicBlock *LParent = LInst->getParent(),
598 *RParent = RInst->getParent();
599 if (LParent != RParent) {
600 unsigned LDepth = LI->getLoopDepth(LParent),
601 RDepth = LI->getLoopDepth(RParent);
602 if (LDepth != RDepth)
603 return (int)LDepth - (int)RDepth;
604 }
605
606 // Compare the number of operands.
607 unsigned LNumOps = LInst->getNumOperands(),
608 RNumOps = RInst->getNumOperands();
609 if (LNumOps != RNumOps)
610 return (int)LNumOps - (int)RNumOps;
611
612 for (unsigned Idx : seq(0u, LNumOps)) {
613 int Result =
614 CompareValueComplexity(EqCache, LI, LInst->getOperand(Idx),
615 RInst->getOperand(Idx), Depth + 1);
616 if (Result != 0)
617 return Result;
618 }
619 }
620
621 EqCache.insert({LV, RV});
622 return 0;
623}
624
625// Return negative, zero, or positive, if LHS is less than, equal to, or greater
626// than RHS, respectively. A three-way result allows recursive comparisons to be
627// more efficient.
628static int CompareSCEVComplexity(
629 SmallSet<std::pair<const SCEV *, const SCEV *>, 8> &EqCacheSCEV,
630 const LoopInfo *const LI, const SCEV *LHS, const SCEV *RHS,
631 DominatorTree &DT, unsigned Depth = 0) {
632 // Fast-path: SCEVs are uniqued so we can do a quick equality check.
633 if (LHS == RHS)
634 return 0;
635
636 // Primarily, sort the SCEVs by their getSCEVType().
637 unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
638 if (LType != RType)
639 return (int)LType - (int)RType;
640
641 if (Depth > MaxSCEVCompareDepth || EqCacheSCEV.count({LHS, RHS}))
642 return 0;
643 // Aside from the getSCEVType() ordering, the particular ordering
644 // isn't very important except that it's beneficial to be consistent,
645 // so that (a + b) and (b + a) don't end up as different expressions.
646 switch (static_cast<SCEVTypes>(LType)) {
647 case scUnknown: {
648 const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
649 const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
650
651 SmallSet<std::pair<Value *, Value *>, 8> EqCache;
652 int X = CompareValueComplexity(EqCache, LI, LU->getValue(), RU->getValue(),
653 Depth + 1);
654 if (X == 0)
655 EqCacheSCEV.insert({LHS, RHS});
656 return X;
657 }
658
659 case scConstant: {
660 const SCEVConstant *LC = cast<SCEVConstant>(LHS);
661 const SCEVConstant *RC = cast<SCEVConstant>(RHS);
662
663 // Compare constant values.
664 const APInt &LA = LC->getAPInt();
665 const APInt &RA = RC->getAPInt();
666 unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth();
667 if (LBitWidth != RBitWidth)
668 return (int)LBitWidth - (int)RBitWidth;
669 return LA.ult(RA) ? -1 : 1;
670 }
671
672 case scAddRecExpr: {
673 const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS);
674 const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
675
676 // There is always a dominance between two recs that are used by one SCEV,
677 // so we can safely sort recs by loop header dominance. We require such
678 // order in getAddExpr.
679 const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop();
680 if (LLoop != RLoop) {
681 const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader();
682 assert(LHead != RHead && "Two loops share the same header?")((LHead != RHead && "Two loops share the same header?"
) ? static_cast<void> (0) : __assert_fail ("LHead != RHead && \"Two loops share the same header?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 682, __PRETTY_FUNCTION__))
;
683 if (DT.dominates(LHead, RHead))
684 return 1;
685 else
686 assert(DT.dominates(RHead, LHead) &&((DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 687, __PRETTY_FUNCTION__))
687 "No dominance between recurrences used by one SCEV?")((DT.dominates(RHead, LHead) && "No dominance between recurrences used by one SCEV?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 687, __PRETTY_FUNCTION__))
;
688 return -1;
689 }
690
691 // Addrec complexity grows with operand count.
692 unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands();
693 if (LNumOps != RNumOps)
694 return (int)LNumOps - (int)RNumOps;
695
696 // Lexicographically compare.
697 for (unsigned i = 0; i != LNumOps; ++i) {
698 int X = CompareSCEVComplexity(EqCacheSCEV, LI, LA->getOperand(i),
699 RA->getOperand(i), DT, Depth + 1);
700 if (X != 0)
701 return X;
702 }
703 EqCacheSCEV.insert({LHS, RHS});
704 return 0;
705 }
706
707 case scAddExpr:
708 case scMulExpr:
709 case scSMaxExpr:
710 case scUMaxExpr: {
711 const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS);
712 const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
713
714 // Lexicographically compare n-ary expressions.
715 unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
716 if (LNumOps != RNumOps)
717 return (int)LNumOps - (int)RNumOps;
718
719 for (unsigned i = 0; i != LNumOps; ++i) {
720 if (i >= RNumOps)
721 return 1;
722 int X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getOperand(i),
723 RC->getOperand(i), DT, Depth + 1);
724 if (X != 0)
725 return X;
726 }
727 EqCacheSCEV.insert({LHS, RHS});
728 return 0;
729 }
730
731 case scUDivExpr: {
732 const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS);
733 const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
734
735 // Lexicographically compare udiv expressions.
736 int X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getLHS(), RC->getLHS(),
737 DT, Depth + 1);
738 if (X != 0)
739 return X;
740 X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getRHS(), RC->getRHS(), DT,
741 Depth + 1);
742 if (X == 0)
743 EqCacheSCEV.insert({LHS, RHS});
744 return X;
745 }
746
747 case scTruncate:
748 case scZeroExtend:
749 case scSignExtend: {
750 const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS);
751 const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
752
753 // Compare cast expressions by operand.
754 int X = CompareSCEVComplexity(EqCacheSCEV, LI, LC->getOperand(),
755 RC->getOperand(), DT, Depth + 1);
756 if (X == 0)
757 EqCacheSCEV.insert({LHS, RHS});
758 return X;
759 }
760
761 case scCouldNotCompute:
762 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 762)
;
763 }
764 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 764)
;
765}
766
767/// Given a list of SCEV objects, order them by their complexity, and group
768/// objects of the same complexity together by value. When this routine is
769/// finished, we know that any duplicates in the vector are consecutive and that
770/// complexity is monotonically increasing.
771///
772/// Note that we go take special precautions to ensure that we get deterministic
773/// results from this routine. In other words, we don't want the results of
774/// this to depend on where the addresses of various SCEV objects happened to
775/// land in memory.
776static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops,
777 LoopInfo *LI, DominatorTree &DT) {
778 if (Ops.size() < 2) return; // Noop
779
780 SmallSet<std::pair<const SCEV *, const SCEV *>, 8> EqCache;
781 if (Ops.size() == 2) {
782 // This is the common case, which also happens to be trivially simple.
783 // Special case it.
784 const SCEV *&LHS = Ops[0], *&RHS = Ops[1];
785 if (CompareSCEVComplexity(EqCache, LI, RHS, LHS, DT) < 0)
786 std::swap(LHS, RHS);
787 return;
788 }
789
790 // Do the rough sort by complexity.
791 std::stable_sort(Ops.begin(), Ops.end(),
792 [&EqCache, LI, &DT](const SCEV *LHS, const SCEV *RHS) {
793 return
794 CompareSCEVComplexity(EqCache, LI, LHS, RHS, DT) < 0;
795 });
796
797 // Now that we are sorted by complexity, group elements of the same
798 // complexity. Note that this is, at worst, N^2, but the vector is likely to
799 // be extremely short in practice. Note that we take this approach because we
800 // do not want to depend on the addresses of the objects we are grouping.
801 for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
802 const SCEV *S = Ops[i];
803 unsigned Complexity = S->getSCEVType();
804
805 // If there are any objects of the same complexity and same value as this
806 // one, group them.
807 for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
808 if (Ops[j] == S) { // Found a duplicate.
809 // Move it to immediately after i'th element.
810 std::swap(Ops[i+1], Ops[j]);
811 ++i; // no need to rescan it.
812 if (i == e-2) return; // Done!
813 }
814 }
815 }
816}
817
818// Returns the size of the SCEV S.
819static inline int sizeOfSCEV(const SCEV *S) {
820 struct FindSCEVSize {
821 int Size = 0;
822
823 FindSCEVSize() = default;
824
825 bool follow(const SCEV *S) {
826 ++Size;
827 // Keep looking at all operands of S.
828 return true;
829 }
830
831 bool isDone() const {
832 return false;
833 }
834 };
835
836 FindSCEVSize F;
837 SCEVTraversal<FindSCEVSize> ST(F);
838 ST.visitAll(S);
839 return F.Size;
840}
841
842namespace {
843
844struct SCEVDivision : public SCEVVisitor<SCEVDivision, void> {
845public:
846 // Computes the Quotient and Remainder of the division of Numerator by
847 // Denominator.
848 static void divide(ScalarEvolution &SE, const SCEV *Numerator,
849 const SCEV *Denominator, const SCEV **Quotient,
850 const SCEV **Remainder) {
851 assert(Numerator && Denominator && "Uninitialized SCEV")((Numerator && Denominator && "Uninitialized SCEV"
) ? static_cast<void> (0) : __assert_fail ("Numerator && Denominator && \"Uninitialized SCEV\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 851, __PRETTY_FUNCTION__))
;
852
853 SCEVDivision D(SE, Numerator, Denominator);
854
855 // Check for the trivial case here to avoid having to check for it in the
856 // rest of the code.
857 if (Numerator == Denominator) {
858 *Quotient = D.One;
859 *Remainder = D.Zero;
860 return;
861 }
862
863 if (Numerator->isZero()) {
864 *Quotient = D.Zero;
865 *Remainder = D.Zero;
866 return;
867 }
868
869 // A simple case when N/1. The quotient is N.
870 if (Denominator->isOne()) {
871 *Quotient = Numerator;
872 *Remainder = D.Zero;
873 return;
874 }
875
876 // Split the Denominator when it is a product.
877 if (const SCEVMulExpr *T = dyn_cast<SCEVMulExpr>(Denominator)) {
878 const SCEV *Q, *R;
879 *Quotient = Numerator;
880 for (const SCEV *Op : T->operands()) {
881 divide(SE, *Quotient, Op, &Q, &R);
882 *Quotient = Q;
883
884 // Bail out when the Numerator is not divisible by one of the terms of
885 // the Denominator.
886 if (!R->isZero()) {
887 *Quotient = D.Zero;
888 *Remainder = Numerator;
889 return;
890 }
891 }
892 *Remainder = D.Zero;
893 return;
894 }
895
896 D.visit(Numerator);
897 *Quotient = D.Quotient;
898 *Remainder = D.Remainder;
899 }
900
901 // Except in the trivial case described above, we do not know how to divide
902 // Expr by Denominator for the following functions with empty implementation.
903 void visitTruncateExpr(const SCEVTruncateExpr *Numerator) {}
904 void visitZeroExtendExpr(const SCEVZeroExtendExpr *Numerator) {}
905 void visitSignExtendExpr(const SCEVSignExtendExpr *Numerator) {}
906 void visitUDivExpr(const SCEVUDivExpr *Numerator) {}
907 void visitSMaxExpr(const SCEVSMaxExpr *Numerator) {}
908 void visitUMaxExpr(const SCEVUMaxExpr *Numerator) {}
909 void visitUnknown(const SCEVUnknown *Numerator) {}
910 void visitCouldNotCompute(const SCEVCouldNotCompute *Numerator) {}
911
912 void visitConstant(const SCEVConstant *Numerator) {
913 if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) {
914 APInt NumeratorVal = Numerator->getAPInt();
915 APInt DenominatorVal = D->getAPInt();
916 uint32_t NumeratorBW = NumeratorVal.getBitWidth();
917 uint32_t DenominatorBW = DenominatorVal.getBitWidth();
918
919 if (NumeratorBW > DenominatorBW)
920 DenominatorVal = DenominatorVal.sext(NumeratorBW);
921 else if (NumeratorBW < DenominatorBW)
922 NumeratorVal = NumeratorVal.sext(DenominatorBW);
923
924 APInt QuotientVal(NumeratorVal.getBitWidth(), 0);
925 APInt RemainderVal(NumeratorVal.getBitWidth(), 0);
926 APInt::sdivrem(NumeratorVal, DenominatorVal, QuotientVal, RemainderVal);
927 Quotient = SE.getConstant(QuotientVal);
928 Remainder = SE.getConstant(RemainderVal);
929 return;
930 }
931 }
932
933 void visitAddRecExpr(const SCEVAddRecExpr *Numerator) {
934 const SCEV *StartQ, *StartR, *StepQ, *StepR;
935 if (!Numerator->isAffine())
936 return cannotDivide(Numerator);
937 divide(SE, Numerator->getStart(), Denominator, &StartQ, &StartR);
938 divide(SE, Numerator->getStepRecurrence(SE), Denominator, &StepQ, &StepR);
939 // Bail out if the types do not match.
940 Type *Ty = Denominator->getType();
941 if (Ty != StartQ->getType() || Ty != StartR->getType() ||
942 Ty != StepQ->getType() || Ty != StepR->getType())
943 return cannotDivide(Numerator);
944 Quotient = SE.getAddRecExpr(StartQ, StepQ, Numerator->getLoop(),
945 Numerator->getNoWrapFlags());
946 Remainder = SE.getAddRecExpr(StartR, StepR, Numerator->getLoop(),
947 Numerator->getNoWrapFlags());
948 }
949
950 void visitAddExpr(const SCEVAddExpr *Numerator) {
951 SmallVector<const SCEV *, 2> Qs, Rs;
952 Type *Ty = Denominator->getType();
953
954 for (const SCEV *Op : Numerator->operands()) {
955 const SCEV *Q, *R;
956 divide(SE, Op, Denominator, &Q, &R);
957
958 // Bail out if types do not match.
959 if (Ty != Q->getType() || Ty != R->getType())
960 return cannotDivide(Numerator);
961
962 Qs.push_back(Q);
963 Rs.push_back(R);
964 }
965
966 if (Qs.size() == 1) {
967 Quotient = Qs[0];
968 Remainder = Rs[0];
969 return;
970 }
971
972 Quotient = SE.getAddExpr(Qs);
973 Remainder = SE.getAddExpr(Rs);
974 }
975
976 void visitMulExpr(const SCEVMulExpr *Numerator) {
977 SmallVector<const SCEV *, 2> Qs;
978 Type *Ty = Denominator->getType();
979
980 bool FoundDenominatorTerm = false;
981 for (const SCEV *Op : Numerator->operands()) {
982 // Bail out if types do not match.
983 if (Ty != Op->getType())
984 return cannotDivide(Numerator);
985
986 if (FoundDenominatorTerm) {
987 Qs.push_back(Op);
988 continue;
989 }
990
991 // Check whether Denominator divides one of the product operands.
992 const SCEV *Q, *R;
993 divide(SE, Op, Denominator, &Q, &R);
994 if (!R->isZero()) {
995 Qs.push_back(Op);
996 continue;
997 }
998
999 // Bail out if types do not match.
1000 if (Ty != Q->getType())
1001 return cannotDivide(Numerator);
1002
1003 FoundDenominatorTerm = true;
1004 Qs.push_back(Q);
1005 }
1006
1007 if (FoundDenominatorTerm) {
1008 Remainder = Zero;
1009 if (Qs.size() == 1)
1010 Quotient = Qs[0];
1011 else
1012 Quotient = SE.getMulExpr(Qs);
1013 return;
1014 }
1015
1016 if (!isa<SCEVUnknown>(Denominator))
1017 return cannotDivide(Numerator);
1018
1019 // The Remainder is obtained by replacing Denominator by 0 in Numerator.
1020 ValueToValueMap RewriteMap;
1021 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
1022 cast<SCEVConstant>(Zero)->getValue();
1023 Remainder = SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
1024
1025 if (Remainder->isZero()) {
1026 // The Quotient is obtained by replacing Denominator by 1 in Numerator.
1027 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
1028 cast<SCEVConstant>(One)->getValue();
1029 Quotient =
1030 SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
1031 return;
1032 }
1033
1034 // Quotient is (Numerator - Remainder) divided by Denominator.
1035 const SCEV *Q, *R;
1036 const SCEV *Diff = SE.getMinusSCEV(Numerator, Remainder);
1037 // This SCEV does not seem to simplify: fail the division here.
1038 if (sizeOfSCEV(Diff) > sizeOfSCEV(Numerator))
1039 return cannotDivide(Numerator);
1040 divide(SE, Diff, Denominator, &Q, &R);
1041 if (R != Zero)
1042 return cannotDivide(Numerator);
1043 Quotient = Q;
1044 }
1045
1046private:
1047 SCEVDivision(ScalarEvolution &S, const SCEV *Numerator,
1048 const SCEV *Denominator)
1049 : SE(S), Denominator(Denominator) {
1050 Zero = SE.getZero(Denominator->getType());
1051 One = SE.getOne(Denominator->getType());
1052
1053 // We generally do not know how to divide Expr by Denominator. We
1054 // initialize the division to a "cannot divide" state to simplify the rest
1055 // of the code.
1056 cannotDivide(Numerator);
1057 }
1058
1059 // Convenience function for giving up on the division. We set the quotient to
1060 // be equal to zero and the remainder to be equal to the numerator.
1061 void cannotDivide(const SCEV *Numerator) {
1062 Quotient = Zero;
1063 Remainder = Numerator;
1064 }
1065
1066 ScalarEvolution &SE;
1067 const SCEV *Denominator, *Quotient, *Remainder, *Zero, *One;
1068};
1069
1070} // end anonymous namespace
1071
1072//===----------------------------------------------------------------------===//
1073// Simple SCEV method implementations
1074//===----------------------------------------------------------------------===//
1075
1076/// Compute BC(It, K). The result has width W. Assume, K > 0.
1077static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
1078 ScalarEvolution &SE,
1079 Type *ResultTy) {
1080 // Handle the simplest case efficiently.
1081 if (K == 1)
1082 return SE.getTruncateOrZeroExtend(It, ResultTy);
1083
1084 // We are using the following formula for BC(It, K):
1085 //
1086 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K!
1087 //
1088 // Suppose, W is the bitwidth of the return value. We must be prepared for
1089 // overflow. Hence, we must assure that the result of our computation is
1090 // equal to the accurate one modulo 2^W. Unfortunately, division isn't
1091 // safe in modular arithmetic.
1092 //
1093 // However, this code doesn't use exactly that formula; the formula it uses
1094 // is something like the following, where T is the number of factors of 2 in
1095 // K! (i.e. trailing zeros in the binary representation of K!), and ^ is
1096 // exponentiation:
1097 //
1098 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T)
1099 //
1100 // This formula is trivially equivalent to the previous formula. However,
1101 // this formula can be implemented much more efficiently. The trick is that
1102 // K! / 2^T is odd, and exact division by an odd number *is* safe in modular
1103 // arithmetic. To do exact division in modular arithmetic, all we have
1104 // to do is multiply by the inverse. Therefore, this step can be done at
1105 // width W.
1106 //
1107 // The next issue is how to safely do the division by 2^T. The way this
1108 // is done is by doing the multiplication step at a width of at least W + T
1109 // bits. This way, the bottom W+T bits of the product are accurate. Then,
1110 // when we perform the division by 2^T (which is equivalent to a right shift
1111 // by T), the bottom W bits are accurate. Extra bits are okay; they'll get
1112 // truncated out after the division by 2^T.
1113 //
1114 // In comparison to just directly using the first formula, this technique
1115 // is much more efficient; using the first formula requires W * K bits,
1116 // but this formula less than W + K bits. Also, the first formula requires
1117 // a division step, whereas this formula only requires multiplies and shifts.
1118 //
1119 // It doesn't matter whether the subtraction step is done in the calculation
1120 // width or the input iteration count's width; if the subtraction overflows,
1121 // the result must be zero anyway. We prefer here to do it in the width of
1122 // the induction variable because it helps a lot for certain cases; CodeGen
1123 // isn't smart enough to ignore the overflow, which leads to much less
1124 // efficient code if the width of the subtraction is wider than the native
1125 // register width.
1126 //
1127 // (It's possible to not widen at all by pulling out factors of 2 before
1128 // the multiplication; for example, K=2 can be calculated as
1129 // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires
1130 // extra arithmetic, so it's not an obvious win, and it gets
1131 // much more complicated for K > 3.)
1132
1133 // Protection from insane SCEVs; this bound is conservative,
1134 // but it probably doesn't matter.
1135 if (K > 1000)
1136 return SE.getCouldNotCompute();
1137
1138 unsigned W = SE.getTypeSizeInBits(ResultTy);
1139
1140 // Calculate K! / 2^T and T; we divide out the factors of two before
1141 // multiplying for calculating K! / 2^T to avoid overflow.
1142 // Other overflow doesn't matter because we only care about the bottom
1143 // W bits of the result.
1144 APInt OddFactorial(W, 1);
1145 unsigned T = 1;
1146 for (unsigned i = 3; i <= K; ++i) {
1147 APInt Mult(W, i);
1148 unsigned TwoFactors = Mult.countTrailingZeros();
1149 T += TwoFactors;
1150 Mult.lshrInPlace(TwoFactors);
1151 OddFactorial *= Mult;
1152 }
1153
1154 // We need at least W + T bits for the multiplication step
1155 unsigned CalculationBits = W + T;
1156
1157 // Calculate 2^T, at width T+W.
1158 APInt DivFactor = APInt::getOneBitSet(CalculationBits, T);
1159
1160 // Calculate the multiplicative inverse of K! / 2^T;
1161 // this multiplication factor will perform the exact division by
1162 // K! / 2^T.
1163 APInt Mod = APInt::getSignedMinValue(W+1);
1164 APInt MultiplyFactor = OddFactorial.zext(W+1);
1165 MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod);
1166 MultiplyFactor = MultiplyFactor.trunc(W);
1167
1168 // Calculate the product, at width T+W
1169 IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
1170 CalculationBits);
1171 const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
1172 for (unsigned i = 1; i != K; ++i) {
1173 const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
1174 Dividend = SE.getMulExpr(Dividend,
1175 SE.getTruncateOrZeroExtend(S, CalculationTy));
1176 }
1177
1178 // Divide by 2^T
1179 const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor));
1180
1181 // Truncate the result, and divide by K! / 2^T.
1182
1183 return SE.getMulExpr(SE.getConstant(MultiplyFactor),
1184 SE.getTruncateOrZeroExtend(DivResult, ResultTy));
1185}
1186
1187/// Return the value of this chain of recurrences at the specified iteration
1188/// number. We can evaluate this recurrence by multiplying each element in the
1189/// chain by the binomial coefficient corresponding to it. In other words, we
1190/// can evaluate {A,+,B,+,C,+,D} as:
1191///
1192/// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)
1193///
1194/// where BC(It, k) stands for binomial coefficient.
1195const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
1196 ScalarEvolution &SE) const {
1197 const SCEV *Result = getStart();
1198 for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
1199 // The computation is correct in the face of overflow provided that the
1200 // multiplication is performed _after_ the evaluation of the binomial
1201 // coefficient.
1202 const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType());
1203 if (isa<SCEVCouldNotCompute>(Coeff))
1204 return Coeff;
1205
1206 Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));
1207 }
1208 return Result;
1209}
1210
1211//===----------------------------------------------------------------------===//
1212// SCEV Expression folder implementations
1213//===----------------------------------------------------------------------===//
1214
1215const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op,
1216 Type *Ty) {
1217 assert(getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(
Ty) && "This is not a truncating conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1218, __PRETTY_FUNCTION__))
1218 "This is not a truncating conversion!")((getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(
Ty) && "This is not a truncating conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1218, __PRETTY_FUNCTION__))
;
1219 assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1220, __PRETTY_FUNCTION__))
1220 "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1220, __PRETTY_FUNCTION__))
;
1221 Ty = getEffectiveSCEVType(Ty);
1222
1223 FoldingSetNodeID ID;
1224 ID.AddInteger(scTruncate);
1225 ID.AddPointer(Op);
1226 ID.AddPointer(Ty);
1227 void *IP = nullptr;
1228 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1229
1230 // Fold if the operand is constant.
1231 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1232 return getConstant(
1233 cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty)));
1234
1235 // trunc(trunc(x)) --> trunc(x)
1236 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
1237 return getTruncateExpr(ST->getOperand(), Ty);
1238
1239 // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
1240 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1241 return getTruncateOrSignExtend(SS->getOperand(), Ty);
1242
1243 // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
1244 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1245 return getTruncateOrZeroExtend(SZ->getOperand(), Ty);
1246
1247 // trunc(x1+x2+...+xN) --> trunc(x1)+trunc(x2)+...+trunc(xN) if we can
1248 // eliminate all the truncates, or we replace other casts with truncates.
1249 if (const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Op)) {
1250 SmallVector<const SCEV *, 4> Operands;
1251 bool hasTrunc = false;
1252 for (unsigned i = 0, e = SA->getNumOperands(); i != e && !hasTrunc; ++i) {
1253 const SCEV *S = getTruncateExpr(SA->getOperand(i), Ty);
1254 if (!isa<SCEVCastExpr>(SA->getOperand(i)))
1255 hasTrunc = isa<SCEVTruncateExpr>(S);
1256 Operands.push_back(S);
1257 }
1258 if (!hasTrunc)
1259 return getAddExpr(Operands);
1260 UniqueSCEVs.FindNodeOrInsertPos(ID, IP); // Mutates IP, returns NULL.
1261 }
1262
1263 // trunc(x1*x2*...*xN) --> trunc(x1)*trunc(x2)*...*trunc(xN) if we can
1264 // eliminate all the truncates, or we replace other casts with truncates.
1265 if (const SCEVMulExpr *SM = dyn_cast<SCEVMulExpr>(Op)) {
1266 SmallVector<const SCEV *, 4> Operands;
1267 bool hasTrunc = false;
1268 for (unsigned i = 0, e = SM->getNumOperands(); i != e && !hasTrunc; ++i) {
1269 const SCEV *S = getTruncateExpr(SM->getOperand(i), Ty);
1270 if (!isa<SCEVCastExpr>(SM->getOperand(i)))
1271 hasTrunc = isa<SCEVTruncateExpr>(S);
1272 Operands.push_back(S);
1273 }
1274 if (!hasTrunc)
1275 return getMulExpr(Operands);
1276 UniqueSCEVs.FindNodeOrInsertPos(ID, IP); // Mutates IP, returns NULL.
1277 }
1278
1279 // If the input value is a chrec scev, truncate the chrec's operands.
1280 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
1281 SmallVector<const SCEV *, 4> Operands;
1282 for (const SCEV *Op : AddRec->operands())
1283 Operands.push_back(getTruncateExpr(Op, Ty));
1284 return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
1285 }
1286
1287 // The cast wasn't folded; create an explicit cast node. We can reuse
1288 // the existing insert position since if we get here, we won't have
1289 // made any changes which would invalidate it.
1290 SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
1291 Op, Ty);
1292 UniqueSCEVs.InsertNode(S, IP);
1293 addToLoopUseLists(S);
1294 return S;
1295}
1296
1297// Get the limit of a recurrence such that incrementing by Step cannot cause
1298// signed overflow as long as the value of the recurrence within the
1299// loop does not exceed this limit before incrementing.
1300static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step,
1301 ICmpInst::Predicate *Pred,
1302 ScalarEvolution *SE) {
1303 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1304 if (SE->isKnownPositive(Step)) {
1305 *Pred = ICmpInst::ICMP_SLT;
1306 return SE->getConstant(APInt::getSignedMinValue(BitWidth) -
1307 SE->getSignedRangeMax(Step));
1308 }
1309 if (SE->isKnownNegative(Step)) {
1310 *Pred = ICmpInst::ICMP_SGT;
1311 return SE->getConstant(APInt::getSignedMaxValue(BitWidth) -
1312 SE->getSignedRangeMin(Step));
1313 }
1314 return nullptr;
1315}
1316
1317// Get the limit of a recurrence such that incrementing by Step cannot cause
1318// unsigned overflow as long as the value of the recurrence within the loop does
1319// not exceed this limit before incrementing.
1320static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step,
1321 ICmpInst::Predicate *Pred,
1322 ScalarEvolution *SE) {
1323 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1324 *Pred = ICmpInst::ICMP_ULT;
1325
1326 return SE->getConstant(APInt::getMinValue(BitWidth) -
1327 SE->getUnsignedRangeMax(Step));
1328}
1329
1330namespace {
1331
1332struct ExtendOpTraitsBase {
1333 typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *,
1334 unsigned);
1335};
1336
1337// Used to make code generic over signed and unsigned overflow.
1338template <typename ExtendOp> struct ExtendOpTraits {
1339 // Members present:
1340 //
1341 // static const SCEV::NoWrapFlags WrapType;
1342 //
1343 // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr;
1344 //
1345 // static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1346 // ICmpInst::Predicate *Pred,
1347 // ScalarEvolution *SE);
1348};
1349
1350template <>
1351struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase {
1352 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW;
1353
1354 static const GetExtendExprTy GetExtendExpr;
1355
1356 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1357 ICmpInst::Predicate *Pred,
1358 ScalarEvolution *SE) {
1359 return getSignedOverflowLimitForStep(Step, Pred, SE);
1360 }
1361};
1362
1363const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1364 SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr;
1365
1366template <>
1367struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
1368 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW;
1369
1370 static const GetExtendExprTy GetExtendExpr;
1371
1372 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1373 ICmpInst::Predicate *Pred,
1374 ScalarEvolution *SE) {
1375 return getUnsignedOverflowLimitForStep(Step, Pred, SE);
1376 }
1377};
1378
1379const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1380 SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr;
1381
1382} // end anonymous namespace
1383
1384// The recurrence AR has been shown to have no signed/unsigned wrap or something
1385// close to it. Typically, if we can prove NSW/NUW for AR, then we can just as
1386// easily prove NSW/NUW for its preincrement or postincrement sibling. This
1387// allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step +
1388// Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the
1389// expression "Step + sext/zext(PreIncAR)" is congruent with
1390// "sext/zext(PostIncAR)"
1391template <typename ExtendOpTy>
1392static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
1393 ScalarEvolution *SE, unsigned Depth) {
1394 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1395 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1396
1397 const Loop *L = AR->getLoop();
1398 const SCEV *Start = AR->getStart();
1399 const SCEV *Step = AR->getStepRecurrence(*SE);
1400
1401 // Check for a simple looking step prior to loop entry.
1402 const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start);
1403 if (!SA)
1404 return nullptr;
1405
1406 // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV
1407 // subtraction is expensive. For this purpose, perform a quick and dirty
1408 // difference, by checking for Step in the operand list.
1409 SmallVector<const SCEV *, 4> DiffOps;
1410 for (const SCEV *Op : SA->operands())
1411 if (Op != Step)
1412 DiffOps.push_back(Op);
1413
1414 if (DiffOps.size() == SA->getNumOperands())
1415 return nullptr;
1416
1417 // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` +
1418 // `Step`:
1419
1420 // 1. NSW/NUW flags on the step increment.
1421 auto PreStartFlags =
1422 ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW);
1423 const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags);
1424 const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
1425 SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
1426
1427 // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies
1428 // "S+X does not sign/unsign-overflow".
1429 //
1430
1431 const SCEV *BECount = SE->getBackedgeTakenCount(L);
1432 if (PreAR && PreAR->getNoWrapFlags(WrapType) &&
1433 !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount))
1434 return PreStart;
1435
1436 // 2. Direct overflow check on the step operation's expression.
1437 unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
1438 Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
1439 const SCEV *OperandExtendedStart =
1440 SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth),
1441 (SE->*GetExtendExpr)(Step, WideTy, Depth));
1442 if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) {
1443 if (PreAR && AR->getNoWrapFlags(WrapType)) {
1444 // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW
1445 // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then
1446 // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact.
1447 const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(WrapType);
1448 }
1449 return PreStart;
1450 }
1451
1452 // 3. Loop precondition.
1453 ICmpInst::Predicate Pred;
1454 const SCEV *OverflowLimit =
1455 ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE);
1456
1457 if (OverflowLimit &&
1458 SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit))
1459 return PreStart;
1460
1461 return nullptr;
1462}
1463
1464// Get the normalized zero or sign extended expression for this AddRec's Start.
1465template <typename ExtendOpTy>
1466static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty,
1467 ScalarEvolution *SE,
1468 unsigned Depth) {
1469 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1470
1471 const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth);
1472 if (!PreStart)
1473 return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth);
1474
1475 return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty,
1476 Depth),
1477 (SE->*GetExtendExpr)(PreStart, Ty, Depth));
1478}
1479
1480// Try to prove away overflow by looking at "nearby" add recurrences. A
1481// motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it
1482// does not itself wrap then we can conclude that `{1,+,4}` is `nuw`.
1483//
1484// Formally:
1485//
1486// {S,+,X} == {S-T,+,X} + T
1487// => Ext({S,+,X}) == Ext({S-T,+,X} + T)
1488//
1489// If ({S-T,+,X} + T) does not overflow ... (1)
1490//
1491// RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T)
1492//
1493// If {S-T,+,X} does not overflow ... (2)
1494//
1495// RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T)
1496// == {Ext(S-T)+Ext(T),+,Ext(X)}
1497//
1498// If (S-T)+T does not overflow ... (3)
1499//
1500// RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)}
1501// == {Ext(S),+,Ext(X)} == LHS
1502//
1503// Thus, if (1), (2) and (3) are true for some T, then
1504// Ext({S,+,X}) == {Ext(S),+,Ext(X)}
1505//
1506// (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T)
1507// does not overflow" restricted to the 0th iteration. Therefore we only need
1508// to check for (1) and (2).
1509//
1510// In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T
1511// is `Delta` (defined below).
1512template <typename ExtendOpTy>
1513bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start,
1514 const SCEV *Step,
1515 const Loop *L) {
1516 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1517
1518 // We restrict `Start` to a constant to prevent SCEV from spending too much
1519 // time here. It is correct (but more expensive) to continue with a
1520 // non-constant `Start` and do a general SCEV subtraction to compute
1521 // `PreStart` below.
1522 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start);
1523 if (!StartC)
1524 return false;
1525
1526 APInt StartAI = StartC->getAPInt();
1527
1528 for (unsigned Delta : {-2, -1, 1, 2}) {
1529 const SCEV *PreStart = getConstant(StartAI - Delta);
1530
1531 FoldingSetNodeID ID;
1532 ID.AddInteger(scAddRecExpr);
1533 ID.AddPointer(PreStart);
1534 ID.AddPointer(Step);
1535 ID.AddPointer(L);
1536 void *IP = nullptr;
1537 const auto *PreAR =
1538 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
1539
1540 // Give up if we don't already have the add recurrence we need because
1541 // actually constructing an add recurrence is relatively expensive.
1542 if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2)
1543 const SCEV *DeltaS = getConstant(StartC->getType(), Delta);
1544 ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
1545 const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(
1546 DeltaS, &Pred, this);
1547 if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1)
1548 return true;
1549 }
1550 }
1551
1552 return false;
1553}
1554
1555const SCEV *
1556ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1557 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1558, __PRETTY_FUNCTION__))
1558 "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1558, __PRETTY_FUNCTION__))
;
1559 assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1560, __PRETTY_FUNCTION__))
1560 "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1560, __PRETTY_FUNCTION__))
;
1561 Ty = getEffectiveSCEVType(Ty);
1562
1563 // Fold if the operand is constant.
1564 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1565 return getConstant(
1566 cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
1567
1568 // zext(zext(x)) --> zext(x)
1569 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1570 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1571
1572 // Before doing any expensive analysis, check to see if we've already
1573 // computed a SCEV for this Op and Ty.
1574 FoldingSetNodeID ID;
1575 ID.AddInteger(scZeroExtend);
1576 ID.AddPointer(Op);
1577 ID.AddPointer(Ty);
1578 void *IP = nullptr;
1579 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1580 if (Depth > MaxExtDepth) {
1581 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1582 Op, Ty);
1583 UniqueSCEVs.InsertNode(S, IP);
1584 addToLoopUseLists(S);
1585 return S;
1586 }
1587
1588 // zext(trunc(x)) --> zext(x) or x or trunc(x)
1589 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1590 // It's possible the bits taken off by the truncate were all zero bits. If
1591 // so, we should be able to simplify this further.
1592 const SCEV *X = ST->getOperand();
1593 ConstantRange CR = getUnsignedRange(X);
1594 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1595 unsigned NewBits = getTypeSizeInBits(Ty);
1596 if (CR.truncate(TruncBits).zeroExtend(NewBits).contains(
1597 CR.zextOrTrunc(NewBits)))
1598 return getTruncateOrZeroExtend(X, Ty);
1599 }
1600
1601 // If the input value is a chrec scev, and we can prove that the value
1602 // did not overflow the old, smaller, value, we can zero extend all of the
1603 // operands (often constants). This allows analysis of something like
1604 // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
1605 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1606 if (AR->isAffine()) {
1607 const SCEV *Start = AR->getStart();
1608 const SCEV *Step = AR->getStepRecurrence(*this);
1609 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1610 const Loop *L = AR->getLoop();
1611
1612 if (!AR->hasNoUnsignedWrap()) {
1613 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1614 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1615 }
1616
1617 // If we have special knowledge that this addrec won't overflow,
1618 // we don't need to do any further analysis.
1619 if (AR->hasNoUnsignedWrap())
1620 return getAddRecExpr(
1621 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1622 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1623
1624 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1625 // Note that this serves two purposes: It filters out loops that are
1626 // simply not analyzable, and it covers the case where this code is
1627 // being called from within backedge-taken count analysis, such that
1628 // attempting to ask for the backedge-taken count would likely result
1629 // in infinite recursion. In the later case, the analysis code will
1630 // cope with a conservative value, and it will take care to purge
1631 // that value once it has finished.
1632 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
1633 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1634 // Manually compute the final value for AR, checking for
1635 // overflow.
1636
1637 // Check whether the backedge-taken count can be losslessly casted to
1638 // the addrec's type. The count is always unsigned.
1639 const SCEV *CastedMaxBECount =
1640 getTruncateOrZeroExtend(MaxBECount, Start->getType());
1641 const SCEV *RecastedMaxBECount =
1642 getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
1643 if (MaxBECount == RecastedMaxBECount) {
1644 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1645 // Check whether Start+Step*MaxBECount has no unsigned overflow.
1646 const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step,
1647 SCEV::FlagAnyWrap, Depth + 1);
1648 const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul,
1649 SCEV::FlagAnyWrap,
1650 Depth + 1),
1651 WideTy, Depth + 1);
1652 const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1);
1653 const SCEV *WideMaxBECount =
1654 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1655 const SCEV *OperandExtendedAdd =
1656 getAddExpr(WideStart,
1657 getMulExpr(WideMaxBECount,
1658 getZeroExtendExpr(Step, WideTy, Depth + 1),
1659 SCEV::FlagAnyWrap, Depth + 1),
1660 SCEV::FlagAnyWrap, Depth + 1);
1661 if (ZAdd == OperandExtendedAdd) {
1662 // Cache knowledge of AR NUW, which is propagated to this AddRec.
1663 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1664 // Return the expression with the addrec on the outside.
1665 return getAddRecExpr(
1666 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1667 Depth + 1),
1668 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1669 AR->getNoWrapFlags());
1670 }
1671 // Similar to above, only this time treat the step value as signed.
1672 // This covers loops that count down.
1673 OperandExtendedAdd =
1674 getAddExpr(WideStart,
1675 getMulExpr(WideMaxBECount,
1676 getSignExtendExpr(Step, WideTy, Depth + 1),
1677 SCEV::FlagAnyWrap, Depth + 1),
1678 SCEV::FlagAnyWrap, Depth + 1);
1679 if (ZAdd == OperandExtendedAdd) {
1680 // Cache knowledge of AR NW, which is propagated to this AddRec.
1681 // Negative step causes unsigned wrap, but it still can't self-wrap.
1682 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1683 // Return the expression with the addrec on the outside.
1684 return getAddRecExpr(
1685 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1686 Depth + 1),
1687 getSignExtendExpr(Step, Ty, Depth + 1), L,
1688 AR->getNoWrapFlags());
1689 }
1690 }
1691 }
1692
1693 // Normally, in the cases we can prove no-overflow via a
1694 // backedge guarding condition, we can also compute a backedge
1695 // taken count for the loop. The exceptions are assumptions and
1696 // guards present in the loop -- SCEV is not great at exploiting
1697 // these to compute max backedge taken counts, but can still use
1698 // these to prove lack of overflow. Use this fact to avoid
1699 // doing extra work that may not pay off.
1700 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1701 !AC.assumptions().empty()) {
1702 // If the backedge is guarded by a comparison with the pre-inc
1703 // value the addrec is safe. Also, if the entry is guarded by
1704 // a comparison with the start value and the backedge is
1705 // guarded by a comparison with the post-inc value, the addrec
1706 // is safe.
1707 if (isKnownPositive(Step)) {
1708 const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
1709 getUnsignedRangeMax(Step));
1710 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
1711 (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_ULT, Start, N) &&
1712 isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT,
1713 AR->getPostIncExpr(*this), N))) {
1714 // Cache knowledge of AR NUW, which is propagated to this
1715 // AddRec.
1716 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1717 // Return the expression with the addrec on the outside.
1718 return getAddRecExpr(
1719 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1720 Depth + 1),
1721 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1722 AR->getNoWrapFlags());
1723 }
1724 } else if (isKnownNegative(Step)) {
1725 const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
1726 getSignedRangeMin(Step));
1727 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
1728 (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_UGT, Start, N) &&
1729 isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT,
1730 AR->getPostIncExpr(*this), N))) {
1731 // Cache knowledge of AR NW, which is propagated to this
1732 // AddRec. Negative step causes unsigned wrap, but it
1733 // still can't self-wrap.
1734 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1735 // Return the expression with the addrec on the outside.
1736 return getAddRecExpr(
1737 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1738 Depth + 1),
1739 getSignExtendExpr(Step, Ty, Depth + 1), L,
1740 AR->getNoWrapFlags());
1741 }
1742 }
1743 }
1744
1745 if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
1746 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1747 return getAddRecExpr(
1748 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1749 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1750 }
1751 }
1752
1753 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1754 // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw>
1755 if (SA->hasNoUnsignedWrap()) {
1756 // If the addition does not unsign overflow then we can, by definition,
1757 // commute the zero extension with the addition operation.
1758 SmallVector<const SCEV *, 4> Ops;
1759 for (const auto *Op : SA->operands())
1760 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1761 return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1);
1762 }
1763 }
1764
1765 // The cast wasn't folded; create an explicit cast node.
1766 // Recompute the insert position, as it may have been invalidated.
1767 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1768 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1769 Op, Ty);
1770 UniqueSCEVs.InsertNode(S, IP);
1771 addToLoopUseLists(S);
1772 return S;
1773}
1774
1775const SCEV *
1776ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1777 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1778, __PRETTY_FUNCTION__))
1778 "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1778, __PRETTY_FUNCTION__))
;
1779 assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1780, __PRETTY_FUNCTION__))
1780 "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 1780, __PRETTY_FUNCTION__))
;
1781 Ty = getEffectiveSCEVType(Ty);
1782
1783 // Fold if the operand is constant.
1784 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1785 return getConstant(
1786 cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
1787
1788 // sext(sext(x)) --> sext(x)
1789 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1790 return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1);
1791
1792 // sext(zext(x)) --> zext(x)
1793 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1794 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1795
1796 // Before doing any expensive analysis, check to see if we've already
1797 // computed a SCEV for this Op and Ty.
1798 FoldingSetNodeID ID;
1799 ID.AddInteger(scSignExtend);
1800 ID.AddPointer(Op);
1801 ID.AddPointer(Ty);
1802 void *IP = nullptr;
1803 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1804 // Limit recursion depth.
1805 if (Depth > MaxExtDepth) {
1806 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1807 Op, Ty);
1808 UniqueSCEVs.InsertNode(S, IP);
1809 addToLoopUseLists(S);
1810 return S;
1811 }
1812
1813 // sext(trunc(x)) --> sext(x) or x or trunc(x)
1814 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1815 // It's possible the bits taken off by the truncate were all sign bits. If
1816 // so, we should be able to simplify this further.
1817 const SCEV *X = ST->getOperand();
1818 ConstantRange CR = getSignedRange(X);
1819 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1820 unsigned NewBits = getTypeSizeInBits(Ty);
1821 if (CR.truncate(TruncBits).signExtend(NewBits).contains(
1822 CR.sextOrTrunc(NewBits)))
1823 return getTruncateOrSignExtend(X, Ty);
1824 }
1825
1826 // sext(C1 + (C2 * x)) --> C1 + sext(C2 * x) if C1 < C2
1827 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1828 if (SA->getNumOperands() == 2) {
1829 auto *SC1 = dyn_cast<SCEVConstant>(SA->getOperand(0));
1830 auto *SMul = dyn_cast<SCEVMulExpr>(SA->getOperand(1));
1831 if (SMul && SC1) {
1832 if (auto *SC2 = dyn_cast<SCEVConstant>(SMul->getOperand(0))) {
1833 const APInt &C1 = SC1->getAPInt();
1834 const APInt &C2 = SC2->getAPInt();
1835 if (C1.isStrictlyPositive() && C2.isStrictlyPositive() &&
1836 C2.ugt(C1) && C2.isPowerOf2())
1837 return getAddExpr(getSignExtendExpr(SC1, Ty, Depth + 1),
1838 getSignExtendExpr(SMul, Ty, Depth + 1),
1839 SCEV::FlagAnyWrap, Depth + 1);
1840 }
1841 }
1842 }
1843
1844 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
1845 if (SA->hasNoSignedWrap()) {
1846 // If the addition does not sign overflow then we can, by definition,
1847 // commute the sign extension with the addition operation.
1848 SmallVector<const SCEV *, 4> Ops;
1849 for (const auto *Op : SA->operands())
1850 Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1));
1851 return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1);
1852 }
1853 }
1854 // If the input value is a chrec scev, and we can prove that the value
1855 // did not overflow the old, smaller, value, we can sign extend all of the
1856 // operands (often constants). This allows analysis of something like
1857 // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
1858 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1859 if (AR->isAffine()) {
1860 const SCEV *Start = AR->getStart();
1861 const SCEV *Step = AR->getStepRecurrence(*this);
1862 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1863 const Loop *L = AR->getLoop();
1864
1865 if (!AR->hasNoSignedWrap()) {
1866 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1867 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1868 }
1869
1870 // If we have special knowledge that this addrec won't overflow,
1871 // we don't need to do any further analysis.
1872 if (AR->hasNoSignedWrap())
1873 return getAddRecExpr(
1874 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
1875 getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW);
1876
1877 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1878 // Note that this serves two purposes: It filters out loops that are
1879 // simply not analyzable, and it covers the case where this code is
1880 // being called from within backedge-taken count analysis, such that
1881 // attempting to ask for the backedge-taken count would likely result
1882 // in infinite recursion. In the later case, the analysis code will
1883 // cope with a conservative value, and it will take care to purge
1884 // that value once it has finished.
1885 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
1886 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1887 // Manually compute the final value for AR, checking for
1888 // overflow.
1889
1890 // Check whether the backedge-taken count can be losslessly casted to
1891 // the addrec's type. The count is always unsigned.
1892 const SCEV *CastedMaxBECount =
1893 getTruncateOrZeroExtend(MaxBECount, Start->getType());
1894 const SCEV *RecastedMaxBECount =
1895 getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
1896 if (MaxBECount == RecastedMaxBECount) {
1897 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1898 // Check whether Start+Step*MaxBECount has no signed overflow.
1899 const SCEV *SMul = getMulExpr(CastedMaxBECount, Step,
1900 SCEV::FlagAnyWrap, Depth + 1);
1901 const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul,
1902 SCEV::FlagAnyWrap,
1903 Depth + 1),
1904 WideTy, Depth + 1);
1905 const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1);
1906 const SCEV *WideMaxBECount =
1907 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1908 const SCEV *OperandExtendedAdd =
1909 getAddExpr(WideStart,
1910 getMulExpr(WideMaxBECount,
1911 getSignExtendExpr(Step, WideTy, Depth + 1),
1912 SCEV::FlagAnyWrap, Depth + 1),
1913 SCEV::FlagAnyWrap, Depth + 1);
1914 if (SAdd == OperandExtendedAdd) {
1915 // Cache knowledge of AR NSW, which is propagated to this AddRec.
1916 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1917 // Return the expression with the addrec on the outside.
1918 return getAddRecExpr(
1919 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
1920 Depth + 1),
1921 getSignExtendExpr(Step, Ty, Depth + 1), L,
1922 AR->getNoWrapFlags());
1923 }
1924 // Similar to above, only this time treat the step value as unsigned.
1925 // This covers loops that count up with an unsigned step.
1926 OperandExtendedAdd =
1927 getAddExpr(WideStart,
1928 getMulExpr(WideMaxBECount,
1929 getZeroExtendExpr(Step, WideTy, Depth + 1),
1930 SCEV::FlagAnyWrap, Depth + 1),
1931 SCEV::FlagAnyWrap, Depth + 1);
1932 if (SAdd == OperandExtendedAdd) {
1933 // If AR wraps around then
1934 //
1935 // abs(Step) * MaxBECount > unsigned-max(AR->getType())
1936 // => SAdd != OperandExtendedAdd
1937 //
1938 // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=>
1939 // (SAdd == OperandExtendedAdd => AR is NW)
1940
1941 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1942
1943 // Return the expression with the addrec on the outside.
1944 return getAddRecExpr(
1945 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
1946 Depth + 1),
1947 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1948 AR->getNoWrapFlags());
1949 }
1950 }
1951 }
1952
1953 // Normally, in the cases we can prove no-overflow via a
1954 // backedge guarding condition, we can also compute a backedge
1955 // taken count for the loop. The exceptions are assumptions and
1956 // guards present in the loop -- SCEV is not great at exploiting
1957 // these to compute max backedge taken counts, but can still use
1958 // these to prove lack of overflow. Use this fact to avoid
1959 // doing extra work that may not pay off.
1960
1961 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1962 !AC.assumptions().empty()) {
1963 // If the backedge is guarded by a comparison with the pre-inc
1964 // value the addrec is safe. Also, if the entry is guarded by
1965 // a comparison with the start value and the backedge is
1966 // guarded by a comparison with the post-inc value, the addrec
1967 // is safe.
1968 ICmpInst::Predicate Pred;
1969 const SCEV *OverflowLimit =
1970 getSignedOverflowLimitForStep(Step, &Pred, this);
1971 if (OverflowLimit &&
1972 (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
1973 (isLoopEntryGuardedByCond(L, Pred, Start, OverflowLimit) &&
1974 isLoopBackedgeGuardedByCond(L, Pred, AR->getPostIncExpr(*this),
1975 OverflowLimit)))) {
1976 // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec.
1977 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1978 return getAddRecExpr(
1979 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
1980 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1981 }
1982 }
1983
1984 // If Start and Step are constants, check if we can apply this
1985 // transformation:
1986 // sext{C1,+,C2} --> C1 + sext{0,+,C2} if C1 < C2
1987 auto *SC1 = dyn_cast<SCEVConstant>(Start);
1988 auto *SC2 = dyn_cast<SCEVConstant>(Step);
1989 if (SC1 && SC2) {
1990 const APInt &C1 = SC1->getAPInt();
1991 const APInt &C2 = SC2->getAPInt();
1992 if (C1.isStrictlyPositive() && C2.isStrictlyPositive() && C2.ugt(C1) &&
1993 C2.isPowerOf2()) {
1994 Start = getSignExtendExpr(Start, Ty, Depth + 1);
1995 const SCEV *NewAR = getAddRecExpr(getZero(AR->getType()), Step, L,
1996 AR->getNoWrapFlags());
1997 return getAddExpr(Start, getSignExtendExpr(NewAR, Ty, Depth + 1),
1998 SCEV::FlagAnyWrap, Depth + 1);
1999 }
2000 }
2001
2002 if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
2003 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
2004 return getAddRecExpr(
2005 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2006 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
2007 }
2008 }
2009
2010 // If the input value is provably positive and we could not simplify
2011 // away the sext build a zext instead.
2012 if (isKnownNonNegative(Op))
2013 return getZeroExtendExpr(Op, Ty, Depth + 1);
2014
2015 // The cast wasn't folded; create an explicit cast node.
2016 // Recompute the insert position, as it may have been invalidated.
2017 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
2018 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
2019 Op, Ty);
2020 UniqueSCEVs.InsertNode(S, IP);
2021 addToLoopUseLists(S);
2022 return S;
2023}
2024
2025/// getAnyExtendExpr - Return a SCEV for the given operand extended with
2026/// unspecified bits out to the given type.
2027const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
2028 Type *Ty) {
2029 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2030, __PRETTY_FUNCTION__))
2030 "This is not an extending conversion!")((getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(
Ty) && "This is not an extending conversion!") ? static_cast
<void> (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2030, __PRETTY_FUNCTION__))
;
2031 assert(isSCEVable(Ty) &&((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2032, __PRETTY_FUNCTION__))
2032 "This is not a conversion to a SCEVable type!")((isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2032, __PRETTY_FUNCTION__))
;
2033 Ty = getEffectiveSCEVType(Ty);
2034
2035 // Sign-extend negative constants.
2036 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
2037 if (SC->getAPInt().isNegative())
2038 return getSignExtendExpr(Op, Ty);
2039
2040 // Peel off a truncate cast.
2041 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
2042 const SCEV *NewOp = T->getOperand();
2043 if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
2044 return getAnyExtendExpr(NewOp, Ty);
2045 return getTruncateOrNoop(NewOp, Ty);
2046 }
2047
2048 // Next try a zext cast. If the cast is folded, use it.
2049 const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
2050 if (!isa<SCEVZeroExtendExpr>(ZExt))
2051 return ZExt;
2052
2053 // Next try a sext cast. If the cast is folded, use it.
2054 const SCEV *SExt = getSignExtendExpr(Op, Ty);
2055 if (!isa<SCEVSignExtendExpr>(SExt))
2056 return SExt;
2057
2058 // Force the cast to be folded into the operands of an addrec.
2059 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
2060 SmallVector<const SCEV *, 4> Ops;
2061 for (const SCEV *Op : AR->operands())
2062 Ops.push_back(getAnyExtendExpr(Op, Ty));
2063 return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
2064 }
2065
2066 // If the expression is obviously signed, use the sext cast value.
2067 if (isa<SCEVSMaxExpr>(Op))
2068 return SExt;
2069
2070 // Absent any other information, use the zext cast value.
2071 return ZExt;
2072}
2073
2074/// Process the given Ops list, which is a list of operands to be added under
2075/// the given scale, update the given map. This is a helper function for
2076/// getAddRecExpr. As an example of what it does, given a sequence of operands
2077/// that would form an add expression like this:
2078///
2079/// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r)
2080///
2081/// where A and B are constants, update the map with these values:
2082///
2083/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
2084///
2085/// and add 13 + A*B*29 to AccumulatedConstant.
2086/// This will allow getAddRecExpr to produce this:
2087///
2088/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
2089///
2090/// This form often exposes folding opportunities that are hidden in
2091/// the original operand list.
2092///
2093/// Return true iff it appears that any interesting folding opportunities
2094/// may be exposed. This helps getAddRecExpr short-circuit extra work in
2095/// the common case where no interesting opportunities are present, and
2096/// is also used as a check to avoid infinite recursion.
2097static bool
2098CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
2099 SmallVectorImpl<const SCEV *> &NewOps,
2100 APInt &AccumulatedConstant,
2101 const SCEV *const *Ops, size_t NumOperands,
2102 const APInt &Scale,
2103 ScalarEvolution &SE) {
2104 bool Interesting = false;
2105
2106 // Iterate over the add operands. They are sorted, with constants first.
2107 unsigned i = 0;
2108 while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2109 ++i;
2110 // Pull a buried constant out to the outside.
2111 if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
2112 Interesting = true;
2113 AccumulatedConstant += Scale * C->getAPInt();
2114 }
2115
2116 // Next comes everything else. We're especially interested in multiplies
2117 // here, but they're in the middle, so just visit the rest with one loop.
2118 for (; i != NumOperands; ++i) {
2119 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
2120 if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
2121 APInt NewScale =
2122 Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt();
2123 if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
2124 // A multiplication of a constant with another add; recurse.
2125 const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
2126 Interesting |=
2127 CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2128 Add->op_begin(), Add->getNumOperands(),
2129 NewScale, SE);
2130 } else {
2131 // A multiplication of a constant with some other value. Update
2132 // the map.
2133 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end());
2134 const SCEV *Key = SE.getMulExpr(MulOps);
2135 auto Pair = M.insert({Key, NewScale});
2136 if (Pair.second) {
2137 NewOps.push_back(Pair.first->first);
2138 } else {
2139 Pair.first->second += NewScale;
2140 // The map already had an entry for this value, which may indicate
2141 // a folding opportunity.
2142 Interesting = true;
2143 }
2144 }
2145 } else {
2146 // An ordinary operand. Update the map.
2147 std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
2148 M.insert({Ops[i], Scale});
2149 if (Pair.second) {
2150 NewOps.push_back(Pair.first->first);
2151 } else {
2152 Pair.first->second += Scale;
2153 // The map already had an entry for this value, which may indicate
2154 // a folding opportunity.
2155 Interesting = true;
2156 }
2157 }
2158 }
2159
2160 return Interesting;
2161}
2162
2163// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
2164// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
2165// can't-overflow flags for the operation if possible.
2166static SCEV::NoWrapFlags
2167StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
2168 const SmallVectorImpl<const SCEV *> &Ops,
2169 SCEV::NoWrapFlags Flags) {
2170 using namespace std::placeholders;
2171
2172 using OBO = OverflowingBinaryOperator;
2173
2174 bool CanAnalyze =
2175 Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
2176 (void)CanAnalyze;
2177 assert(CanAnalyze && "don't call from other places!")((CanAnalyze && "don't call from other places!") ? static_cast
<void> (0) : __assert_fail ("CanAnalyze && \"don't call from other places!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2177, __PRETTY_FUNCTION__))
;
2178
2179 int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
2180 SCEV::NoWrapFlags SignOrUnsignWrap =
2181 ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2182
2183 // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
2184 auto IsKnownNonNegative = [&](const SCEV *S) {
2185 return SE->isKnownNonNegative(S);
2186 };
2187
2188 if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
2189 Flags =
2190 ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
2191
2192 SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2193
2194 if (SignOrUnsignWrap != SignOrUnsignMask && Type == scAddExpr &&
2195 Ops.size() == 2 && isa<SCEVConstant>(Ops[0])) {
2196
2197 // (A + C) --> (A + C)<nsw> if the addition does not sign overflow
2198 // (A + C) --> (A + C)<nuw> if the addition does not unsign overflow
2199
2200 const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
2201 if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
2202 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2203 Instruction::Add, C, OBO::NoSignedWrap);
2204 if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
2205 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2206 }
2207 if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
2208 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2209 Instruction::Add, C, OBO::NoUnsignedWrap);
2210 if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
2211 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2212 }
2213 }
2214
2215 return Flags;
2216}
2217
2218bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) {
2219 if (!isLoopInvariant(S, L))
2220 return false;
2221 // If a value depends on a SCEVUnknown which is defined after the loop, we
2222 // conservatively assume that we cannot calculate it at the loop's entry.
2223 struct FindDominatedSCEVUnknown {
2224 bool Found = false;
2225 const Loop *L;
2226 DominatorTree &DT;
2227 LoopInfo &LI;
2228
2229 FindDominatedSCEVUnknown(const Loop *L, DominatorTree &DT, LoopInfo &LI)
2230 : L(L), DT(DT), LI(LI) {}
2231
2232 bool checkSCEVUnknown(const SCEVUnknown *SU) {
2233 if (auto *I = dyn_cast<Instruction>(SU->getValue())) {
2234 if (DT.dominates(L->getHeader(), I->getParent()))
2235 Found = true;
2236 else
2237 assert(DT.dominates(I->getParent(), L->getHeader()) &&((DT.dominates(I->getParent(), L->getHeader()) &&
"No dominance relationship between SCEV and loop?") ? static_cast
<void> (0) : __assert_fail ("DT.dominates(I->getParent(), L->getHeader()) && \"No dominance relationship between SCEV and loop?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2238, __PRETTY_FUNCTION__))
2238 "No dominance relationship between SCEV and loop?")((DT.dominates(I->getParent(), L->getHeader()) &&
"No dominance relationship between SCEV and loop?") ? static_cast
<void> (0) : __assert_fail ("DT.dominates(I->getParent(), L->getHeader()) && \"No dominance relationship between SCEV and loop?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2238, __PRETTY_FUNCTION__))
;
2239 }
2240 return false;
2241 }
2242
2243 bool follow(const SCEV *S) {
2244 switch (static_cast<SCEVTypes>(S->getSCEVType())) {
2245 case scConstant:
2246 return false;
2247 case scAddRecExpr:
2248 case scTruncate:
2249 case scZeroExtend:
2250 case scSignExtend:
2251 case scAddExpr:
2252 case scMulExpr:
2253 case scUMaxExpr:
2254 case scSMaxExpr:
2255 case scUDivExpr:
2256 return true;
2257 case scUnknown:
2258 return checkSCEVUnknown(cast<SCEVUnknown>(S));
2259 case scCouldNotCompute:
2260 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2260)
;
2261 }
2262 return false;
2263 }
2264
2265 bool isDone() { return Found; }
2266 };
2267
2268 FindDominatedSCEVUnknown FSU(L, DT, LI);
2269 SCEVTraversal<FindDominatedSCEVUnknown> ST(FSU);
2270 ST.visitAll(S);
2271 return !FSU.Found;
2272}
2273
2274/// Get a canonical add expression, or something simpler if possible.
2275const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2276 SCEV::NoWrapFlags Flags,
2277 unsigned Depth) {
2278 assert(!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&((!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed"
) ? static_cast<void> (0) : __assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2279, __PRETTY_FUNCTION__))
2279 "only nuw or nsw allowed")((!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && "only nuw or nsw allowed"
) ? static_cast<void> (0) : __assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2279, __PRETTY_FUNCTION__))
;
2280 assert(!Ops.empty() && "Cannot get empty add!")((!Ops.empty() && "Cannot get empty add!") ? static_cast
<void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty add!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2280, __PRETTY_FUNCTION__))
;
2281 if (Ops.size() == 1) return Ops[0];
2282#ifndef NDEBUG
2283 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2284 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2285 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVAddExpr operand types don't match!") ? static_cast<void
> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2286, __PRETTY_FUNCTION__))
2286 "SCEVAddExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVAddExpr operand types don't match!") ? static_cast<void
> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2286, __PRETTY_FUNCTION__))
;
2287#endif
2288
2289 // Sort by complexity, this groups all similar expression types together.
2290 GroupByComplexity(Ops, &LI, DT);
2291
2292 Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags);
2293
2294 // If there are any constants, fold them together.
2295 unsigned Idx = 0;
2296 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2297 ++Idx;
2298 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2298, __PRETTY_FUNCTION__))
;
2299 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2300 // We found two constants, fold them together!
2301 Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt());
2302 if (Ops.size() == 2) return Ops[0];
2303 Ops.erase(Ops.begin()+1); // Erase the folded element
2304 LHSC = cast<SCEVConstant>(Ops[0]);
2305 }
2306
2307 // If we are left with a constant zero being added, strip it off.
2308 if (LHSC->getValue()->isZero()) {
2309 Ops.erase(Ops.begin());
2310 --Idx;
2311 }
2312
2313 if (Ops.size() == 1) return Ops[0];
2314 }
2315
2316 // Limit recursion calls depth.
2317 if (Depth > MaxArithDepth)
2318 return getOrCreateAddExpr(Ops, Flags);
2319
2320 // Okay, check to see if the same value occurs in the operand list more than
2321 // once. If so, merge them together into an multiply expression. Since we
2322 // sorted the list, these values are required to be adjacent.
2323 Type *Ty = Ops[0]->getType();
2324 bool FoundMatch = false;
2325 for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
2326 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
2327 // Scan ahead to count how many equal operands there are.
2328 unsigned Count = 2;
2329 while (i+Count != e && Ops[i+Count] == Ops[i])
2330 ++Count;
2331 // Merge the values into a multiply.
2332 const SCEV *Scale = getConstant(Ty, Count);
2333 const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1);
2334 if (Ops.size() == Count)
2335 return Mul;
2336 Ops[i] = Mul;
2337 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
2338 --i; e -= Count - 1;
2339 FoundMatch = true;
2340 }
2341 if (FoundMatch)
2342 return getAddExpr(Ops, Flags);
2343
2344 // Check for truncates. If all the operands are truncated from the same
2345 // type, see if factoring out the truncate would permit the result to be
2346 // folded. eg., n*trunc(x) + m*trunc(y) --> trunc(trunc(m)*x + trunc(n)*y)
2347 // if the contents of the resulting outer trunc fold to something simple.
2348 auto FindTruncSrcType = [&]() -> Type * {
2349 // We're ultimately looking to fold an addrec of truncs and muls of only
2350 // constants and truncs, so if we find any other types of SCEV
2351 // as operands of the addrec then we bail and return nullptr here.
2352 // Otherwise, we return the type of the operand of a trunc that we find.
2353 if (auto *T = dyn_cast<SCEVTruncateExpr>(Ops[Idx]))
2354 return T->getOperand()->getType();
2355 if (const auto *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2356 const auto *LastOp = Mul->getOperand(Mul->getNumOperands() - 1);
2357 if (const auto *T = dyn_cast<SCEVTruncateExpr>(LastOp))
2358 return T->getOperand()->getType();
2359 }
2360 return nullptr;
2361 };
2362 if (auto *SrcType = FindTruncSrcType()) {
2363 SmallVector<const SCEV *, 8> LargeOps;
2364 bool Ok = true;
2365 // Check all the operands to see if they can be represented in the
2366 // source type of the truncate.
2367 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
2368 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
2369 if (T->getOperand()->getType() != SrcType) {
2370 Ok = false;
2371 break;
2372 }
2373 LargeOps.push_back(T->getOperand());
2374 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2375 LargeOps.push_back(getAnyExtendExpr(C, SrcType));
2376 } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
2377 SmallVector<const SCEV *, 8> LargeMulOps;
2378 for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
2379 if (const SCEVTruncateExpr *T =
2380 dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
2381 if (T->getOperand()->getType() != SrcType) {
2382 Ok = false;
2383 break;
2384 }
2385 LargeMulOps.push_back(T->getOperand());
2386 } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) {
2387 LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
2388 } else {
2389 Ok = false;
2390 break;
2391 }
2392 }
2393 if (Ok)
2394 LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1));
2395 } else {
2396 Ok = false;
2397 break;
2398 }
2399 }
2400 if (Ok) {
2401 // Evaluate the expression in the larger type.
2402 const SCEV *Fold = getAddExpr(LargeOps, Flags, Depth + 1);
2403 // If it folds to something simple, use it. Otherwise, don't.
2404 if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
2405 return getTruncateExpr(Fold, Ty);
2406 }
2407 }
2408
2409 // Skip past any other cast SCEVs.
2410 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
2411 ++Idx;
2412
2413 // If there are add operands they would be next.
2414 if (Idx < Ops.size()) {
2415 bool DeletedAdd = false;
2416 while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
2417 if (Ops.size() > AddOpsInlineThreshold ||
2418 Add->getNumOperands() > AddOpsInlineThreshold)
2419 break;
2420 // If we have an add, expand the add operands onto the end of the operands
2421 // list.
2422 Ops.erase(Ops.begin()+Idx);
2423 Ops.append(Add->op_begin(), Add->op_end());
2424 DeletedAdd = true;
2425 }
2426
2427 // If we deleted at least one add, we added operands to the end of the list,
2428 // and they are not necessarily sorted. Recurse to resort and resimplify
2429 // any operands we just acquired.
2430 if (DeletedAdd)
2431 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2432 }
2433
2434 // Skip over the add expression until we get to a multiply.
2435 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2436 ++Idx;
2437
2438 // Check to see if there are any folding opportunities present with
2439 // operands multiplied by constant values.
2440 if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
2441 uint64_t BitWidth = getTypeSizeInBits(Ty);
2442 DenseMap<const SCEV *, APInt> M;
2443 SmallVector<const SCEV *, 8> NewOps;
2444 APInt AccumulatedConstant(BitWidth, 0);
2445 if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2446 Ops.data(), Ops.size(),
2447 APInt(BitWidth, 1), *this)) {
2448 struct APIntCompare {
2449 bool operator()(const APInt &LHS, const APInt &RHS) const {
2450 return LHS.ult(RHS);
2451 }
2452 };
2453
2454 // Some interesting folding opportunity is present, so its worthwhile to
2455 // re-generate the operands list. Group the operands by constant scale,
2456 // to avoid multiplying by the same constant scale multiple times.
2457 std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
2458 for (const SCEV *NewOp : NewOps)
2459 MulOpLists[M.find(NewOp)->second].push_back(NewOp);
2460 // Re-generate the operands list.
2461 Ops.clear();
2462 if (AccumulatedConstant != 0)
2463 Ops.push_back(getConstant(AccumulatedConstant));
2464 for (auto &MulOp : MulOpLists)
2465 if (MulOp.first != 0)
2466 Ops.push_back(getMulExpr(
2467 getConstant(MulOp.first),
2468 getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1),
2469 SCEV::FlagAnyWrap, Depth + 1));
2470 if (Ops.empty())
2471 return getZero(Ty);
2472 if (Ops.size() == 1)
2473 return Ops[0];
2474 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2475 }
2476 }
2477
2478 // If we are adding something to a multiply expression, make sure the
2479 // something is not already an operand of the multiply. If so, merge it into
2480 // the multiply.
2481 for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
2482 const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
2483 for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
2484 const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
2485 if (isa<SCEVConstant>(MulOpSCEV))
2486 continue;
2487 for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
2488 if (MulOpSCEV == Ops[AddOp]) {
2489 // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
2490 const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
2491 if (Mul->getNumOperands() != 2) {
2492 // If the multiply has more than two operands, we must get the
2493 // Y*Z term.
2494 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2495 Mul->op_begin()+MulOp);
2496 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2497 InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2498 }
2499 SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul};
2500 const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2501 const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV,
2502 SCEV::FlagAnyWrap, Depth + 1);
2503 if (Ops.size() == 2) return OuterMul;
2504 if (AddOp < Idx) {
2505 Ops.erase(Ops.begin()+AddOp);
2506 Ops.erase(Ops.begin()+Idx-1);
2507 } else {
2508 Ops.erase(Ops.begin()+Idx);
2509 Ops.erase(Ops.begin()+AddOp-1);
2510 }
2511 Ops.push_back(OuterMul);
2512 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2513 }
2514
2515 // Check this multiply against other multiplies being added together.
2516 for (unsigned OtherMulIdx = Idx+1;
2517 OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
2518 ++OtherMulIdx) {
2519 const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
2520 // If MulOp occurs in OtherMul, we can fold the two multiplies
2521 // together.
2522 for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
2523 OMulOp != e; ++OMulOp)
2524 if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
2525 // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
2526 const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
2527 if (Mul->getNumOperands() != 2) {
2528 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2529 Mul->op_begin()+MulOp);
2530 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2531 InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2532 }
2533 const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
2534 if (OtherMul->getNumOperands() != 2) {
2535 SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
2536 OtherMul->op_begin()+OMulOp);
2537 MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
2538 InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2539 }
2540 SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2};
2541 const SCEV *InnerMulSum =
2542 getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2543 const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum,
2544 SCEV::FlagAnyWrap, Depth + 1);
2545 if (Ops.size() == 2) return OuterMul;
2546 Ops.erase(Ops.begin()+Idx);
2547 Ops.erase(Ops.begin()+OtherMulIdx-1);
2548 Ops.push_back(OuterMul);
2549 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2550 }
2551 }
2552 }
2553 }
2554
2555 // If there are any add recurrences in the operands list, see if any other
2556 // added values are loop invariant. If so, we can fold them into the
2557 // recurrence.
2558 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2559 ++Idx;
2560
2561 // Scan over all recurrences, trying to fold loop invariants into them.
2562 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2563 // Scan all of the other operands to this add and add them to the vector if
2564 // they are loop invariant w.r.t. the recurrence.
2565 SmallVector<const SCEV *, 8> LIOps;
2566 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2567 const Loop *AddRecLoop = AddRec->getLoop();
2568 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2569 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2570 LIOps.push_back(Ops[i]);
2571 Ops.erase(Ops.begin()+i);
2572 --i; --e;
2573 }
2574
2575 // If we found some loop invariants, fold them into the recurrence.
2576 if (!LIOps.empty()) {
2577 // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
2578 LIOps.push_back(AddRec->getStart());
2579
2580 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2581 AddRec->op_end());
2582 // This follows from the fact that the no-wrap flags on the outer add
2583 // expression are applicable on the 0th iteration, when the add recurrence
2584 // will be equal to its start value.
2585 AddRecOps[0] = getAddExpr(LIOps, Flags, Depth + 1);
2586
2587 // Build the new addrec. Propagate the NUW and NSW flags if both the
2588 // outer add and the inner addrec are guaranteed to have no overflow.
2589 // Always propagate NW.
2590 Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
2591 const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
2592
2593 // If all of the other operands were loop invariant, we are done.
2594 if (Ops.size() == 1) return NewRec;
2595
2596 // Otherwise, add the folded AddRec by the non-invariant parts.
2597 for (unsigned i = 0;; ++i)
2598 if (Ops[i] == AddRec) {
2599 Ops[i] = NewRec;
2600 break;
2601 }
2602 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2603 }
2604
2605 // Okay, if there weren't any loop invariants to be folded, check to see if
2606 // there are multiple AddRec's with the same loop induction variable being
2607 // added together. If so, we can fold them.
2608 for (unsigned OtherIdx = Idx+1;
2609 OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2610 ++OtherIdx) {
2611 // We expect the AddRecExpr's to be sorted in reverse dominance order,
2612 // so that the 1st found AddRecExpr is dominated by all others.
2613 assert(DT.dominates(((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->
getLoop()->getHeader(), AddRec->getLoop()->getHeader
()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2616, __PRETTY_FUNCTION__))
2614 cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(),((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->
getLoop()->getHeader(), AddRec->getLoop()->getHeader
()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2616, __PRETTY_FUNCTION__))
2615 AddRec->getLoop()->getHeader()) &&((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->
getLoop()->getHeader(), AddRec->getLoop()->getHeader
()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2616, __PRETTY_FUNCTION__))
2616 "AddRecExprs are not sorted in reverse dominance order?")((DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->
getLoop()->getHeader(), AddRec->getLoop()->getHeader
()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? static_cast<void> (0) : __assert_fail ("DT.dominates( cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->getLoop()->getHeader()) && \"AddRecExprs are not sorted in reverse dominance order?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2616, __PRETTY_FUNCTION__))
;
2617 if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
2618 // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
2619 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2620 AddRec->op_end());
2621 for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2622 ++OtherIdx) {
2623 const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2624 if (OtherAddRec->getLoop() == AddRecLoop) {
2625 for (unsigned i = 0, e = OtherAddRec->getNumOperands();
2626 i != e; ++i) {
2627 if (i >= AddRecOps.size()) {
2628 AddRecOps.append(OtherAddRec->op_begin()+i,
2629 OtherAddRec->op_end());
2630 break;
2631 }
2632 SmallVector<const SCEV *, 2> TwoOps = {
2633 AddRecOps[i], OtherAddRec->getOperand(i)};
2634 AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2635 }
2636 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2637 }
2638 }
2639 // Step size has changed, so we cannot guarantee no self-wraparound.
2640 Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
2641 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2642 }
2643 }
2644
2645 // Otherwise couldn't fold anything into this recurrence. Move onto the
2646 // next one.
2647 }
2648
2649 // Okay, it looks like we really DO need an add expr. Check to see if we
2650 // already have one, otherwise create a new one.
2651 return getOrCreateAddExpr(Ops, Flags);
2652}
2653
2654const SCEV *
2655ScalarEvolution::getOrCreateAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2656 SCEV::NoWrapFlags Flags) {
2657 FoldingSetNodeID ID;
2658 ID.AddInteger(scAddExpr);
2659 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2660 ID.AddPointer(Ops[i]);
2661 void *IP = nullptr;
2662 SCEVAddExpr *S =
2663 static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2664 if (!S) {
2665 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2666 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2667 S = new (SCEVAllocator)
2668 SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size());
2669 UniqueSCEVs.InsertNode(S, IP);
2670 addToLoopUseLists(S);
2671 }
2672 S->setNoWrapFlags(Flags);
2673 return S;
2674}
2675
2676const SCEV *
2677ScalarEvolution::getOrCreateMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2678 SCEV::NoWrapFlags Flags) {
2679 FoldingSetNodeID ID;
2680 ID.AddInteger(scMulExpr);
2681 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2682 ID.AddPointer(Ops[i]);
2683 void *IP = nullptr;
2684 SCEVMulExpr *S =
2685 static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2686 if (!S) {
2687 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2688 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2689 S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
2690 O, Ops.size());
2691 UniqueSCEVs.InsertNode(S, IP);
2692 addToLoopUseLists(S);
2693 }
2694 S->setNoWrapFlags(Flags);
2695 return S;
2696}
2697
2698static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
2699 uint64_t k = i*j;
2700 if (j > 1 && k / j != i) Overflow = true;
2701 return k;
2702}
2703
2704/// Compute the result of "n choose k", the binomial coefficient. If an
2705/// intermediate computation overflows, Overflow will be set and the return will
2706/// be garbage. Overflow is not cleared on absence of overflow.
2707static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) {
2708 // We use the multiplicative formula:
2709 // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 .
2710 // At each iteration, we take the n-th term of the numeral and divide by the
2711 // (k-n)th term of the denominator. This division will always produce an
2712 // integral result, and helps reduce the chance of overflow in the
2713 // intermediate computations. However, we can still overflow even when the
2714 // final result would fit.
2715
2716 if (n == 0 || n == k) return 1;
2717 if (k > n) return 0;
2718
2719 if (k > n/2)
2720 k = n-k;
2721
2722 uint64_t r = 1;
2723 for (uint64_t i = 1; i <= k; ++i) {
2724 r = umul_ov(r, n-(i-1), Overflow);
2725 r /= i;
2726 }
2727 return r;
2728}
2729
2730/// Determine if any of the operands in this SCEV are a constant or if
2731/// any of the add or multiply expressions in this SCEV contain a constant.
2732static bool containsConstantInAddMulChain(const SCEV *StartExpr) {
2733 struct FindConstantInAddMulChain {
2734 bool FoundConstant = false;
2735
2736 bool follow(const SCEV *S) {
2737 FoundConstant |= isa<SCEVConstant>(S);
2738 return isa<SCEVAddExpr>(S) || isa<SCEVMulExpr>(S);
2739 }
2740
2741 bool isDone() const {
2742 return FoundConstant;
2743 }
2744 };
2745
2746 FindConstantInAddMulChain F;
2747 SCEVTraversal<FindConstantInAddMulChain> ST(F);
2748 ST.visitAll(StartExpr);
2749 return F.FoundConstant;
2750}
2751
2752/// Get a canonical multiply expression, or something simpler if possible.
2753const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2754 SCEV::NoWrapFlags Flags,
2755 unsigned Depth) {
2756 assert(Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&((Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&
"only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail
("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2757, __PRETTY_FUNCTION__))
2757 "only nuw or nsw allowed")((Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&
"only nuw or nsw allowed") ? static_cast<void> (0) : __assert_fail
("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2757, __PRETTY_FUNCTION__))
;
2758 assert(!Ops.empty() && "Cannot get empty mul!")((!Ops.empty() && "Cannot get empty mul!") ? static_cast
<void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty mul!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2758, __PRETTY_FUNCTION__))
;
2759 if (Ops.size() == 1) return Ops[0];
2760#ifndef NDEBUG
2761 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2762 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2763 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVMulExpr operand types don't match!") ? static_cast<void
> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2764, __PRETTY_FUNCTION__))
2764 "SCEVMulExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVMulExpr operand types don't match!") ? static_cast<void
> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 2764, __PRETTY_FUNCTION__))
;
2765#endif
2766
2767 // Sort by complexity, this groups all similar expression types together.
2768 GroupByComplexity(Ops, &LI, DT);
2769
2770 Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags);
2771
2772 // Limit recursion calls depth.
2773 if (Depth > MaxArithDepth)
2774 return getOrCreateMulExpr(Ops, Flags);
2775
2776 // If there are any constants, fold them together.
2777 unsigned Idx = 0;
2778 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2779
2780 // C1*(C2+V) -> C1*C2 + C1*V
2781 if (Ops.size() == 2)
2782 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
2783 // If any of Add's ops are Adds or Muls with a constant,
2784 // apply this transformation as well.
2785 if (Add->getNumOperands() == 2)
2786 // TODO: There are some cases where this transformation is not
2787 // profitable, for example:
2788 // Add = (C0 + X) * Y + Z.
2789 // Maybe the scope of this transformation should be narrowed down.
2790 if (containsConstantInAddMulChain(Add))
2791 return getAddExpr(getMulExpr(LHSC, Add->getOperand(0),
2792 SCEV::FlagAnyWrap, Depth + 1),
2793 getMulExpr(LHSC, Add->getOperand(1),
2794 SCEV::FlagAnyWrap, Depth + 1),
2795 SCEV::FlagAnyWrap, Depth + 1);
2796
2797 ++Idx;
2798 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2799 // We found two constants, fold them together!
2800 ConstantInt *Fold =
2801 ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt());
2802 Ops[0] = getConstant(Fold);
2803 Ops.erase(Ops.begin()+1); // Erase the folded element
2804 if (Ops.size() == 1) return Ops[0];
2805 LHSC = cast<SCEVConstant>(Ops[0]);
2806 }
2807
2808 // If we are left with a constant one being multiplied, strip it off.
2809 if (cast<SCEVConstant>(Ops[0])->getValue()->isOne()) {
2810 Ops.erase(Ops.begin());
2811 --Idx;
2812 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
2813 // If we have a multiply of zero, it will always be zero.
2814 return Ops[0];
2815 } else if (Ops[0]->isAllOnesValue()) {
2816 // If we have a mul by -1 of an add, try distributing the -1 among the
2817 // add operands.
2818 if (Ops.size() == 2) {
2819 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
2820 SmallVector<const SCEV *, 4> NewOps;
2821 bool AnyFolded = false;
2822 for (const SCEV *AddOp : Add->operands()) {
2823 const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap,
2824 Depth + 1);
2825 if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
2826 NewOps.push_back(Mul);
2827 }
2828 if (AnyFolded)
2829 return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1);
2830 } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
2831 // Negation preserves a recurrence's no self-wrap property.
2832 SmallVector<const SCEV *, 4> Operands;
2833 for (const SCEV *AddRecOp : AddRec->operands())
2834 Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap,
2835 Depth + 1));
2836
2837 return getAddRecExpr(Operands, AddRec->getLoop(),
2838 AddRec->getNoWrapFlags(SCEV::FlagNW));
2839 }
2840 }
2841 }
2842
2843 if (Ops.size() == 1)
2844 return Ops[0];
2845 }
2846
2847 // Skip over the add expression until we get to a multiply.
2848 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2849 ++Idx;
2850
2851 // If there are mul operands inline them all into this expression.
2852 if (Idx < Ops.size()) {
2853 bool DeletedMul = false;
2854 while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2855 if (Ops.size() > MulOpsInlineThreshold)
2856 break;
2857 // If we have an mul, expand the mul operands onto the end of the
2858 // operands list.
2859 Ops.erase(Ops.begin()+Idx);
2860 Ops.append(Mul->op_begin(), Mul->op_end());
2861 DeletedMul = true;
2862 }
2863
2864 // If we deleted at least one mul, we added operands to the end of the
2865 // list, and they are not necessarily sorted. Recurse to resort and
2866 // resimplify any operands we just acquired.
2867 if (DeletedMul)
2868 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2869 }
2870
2871 // If there are any add recurrences in the operands list, see if any other
2872 // added values are loop invariant. If so, we can fold them into the
2873 // recurrence.
2874 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2875 ++Idx;
2876
2877 // Scan over all recurrences, trying to fold loop invariants into them.
2878 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2879 // Scan all of the other operands to this mul and add them to the vector
2880 // if they are loop invariant w.r.t. the recurrence.
2881 SmallVector<const SCEV *, 8> LIOps;
2882 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2883 const Loop *AddRecLoop = AddRec->getLoop();
2884 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2885 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2886 LIOps.push_back(Ops[i]);
2887 Ops.erase(Ops.begin()+i);
2888 --i; --e;
2889 }
2890
2891 // If we found some loop invariants, fold them into the recurrence.
2892 if (!LIOps.empty()) {
2893 // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
2894 SmallVector<const SCEV *, 4> NewOps;
2895 NewOps.reserve(AddRec->getNumOperands());
2896 const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1);
2897 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
2898 NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i),
2899 SCEV::FlagAnyWrap, Depth + 1));
2900
2901 // Build the new addrec. Propagate the NUW and NSW flags if both the
2902 // outer mul and the inner addrec are guaranteed to have no overflow.
2903 //
2904 // No self-wrap cannot be guaranteed after changing the step size, but
2905 // will be inferred if either NUW or NSW is true.
2906 Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW));
2907 const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags);
2908
2909 // If all of the other operands were loop invariant, we are done.
2910 if (Ops.size() == 1) return NewRec;
2911
2912 // Otherwise, multiply the folded AddRec by the non-invariant parts.
2913 for (unsigned i = 0;; ++i)
2914 if (Ops[i] == AddRec) {
2915 Ops[i] = NewRec;
2916 break;
2917 }
2918 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2919 }
2920
2921 // Okay, if there weren't any loop invariants to be folded, check to see
2922 // if there are multiple AddRec's with the same loop induction variable
2923 // being multiplied together. If so, we can fold them.
2924
2925 // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L>
2926 // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [
2927 // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z
2928 // ]]],+,...up to x=2n}.
2929 // Note that the arguments to choose() are always integers with values
2930 // known at compile time, never SCEV objects.
2931 //
2932 // The implementation avoids pointless extra computations when the two
2933 // addrec's are of different length (mathematically, it's equivalent to
2934 // an infinite stream of zeros on the right).
2935 bool OpsModified = false;
2936 for (unsigned OtherIdx = Idx+1;
2937 OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2938 ++OtherIdx) {
2939 const SCEVAddRecExpr *OtherAddRec =
2940 dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2941 if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop)
2942 continue;
2943
2944 // Limit max number of arguments to avoid creation of unreasonably big
2945 // SCEVAddRecs with very complex operands.
2946 if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 >
2947 MaxAddRecSize)
2948 continue;
2949
2950 bool Overflow = false;
2951 Type *Ty = AddRec->getType();
2952 bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64;
2953 SmallVector<const SCEV*, 7> AddRecOps;
2954 for (int x = 0, xe = AddRec->getNumOperands() +
2955 OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) {
2956 const SCEV *Term = getZero(Ty);
2957 for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) {
2958 uint64_t Coeff1 = Choose(x, 2*x - y, Overflow);
2959 for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1),
2960 ze = std::min(x+1, (int)OtherAddRec->getNumOperands());
2961 z < ze && !Overflow; ++z) {
2962 uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow);
2963 uint64_t Coeff;
2964 if (LargerThan64Bits)
2965 Coeff = umul_ov(Coeff1, Coeff2, Overflow);
2966 else
2967 Coeff = Coeff1*Coeff2;
2968 const SCEV *CoeffTerm = getConstant(Ty, Coeff);
2969 const SCEV *Term1 = AddRec->getOperand(y-z);
2970 const SCEV *Term2 = OtherAddRec->getOperand(z);
2971 Term = getAddExpr(Term, getMulExpr(CoeffTerm, Term1, Term2,
2972 SCEV::FlagAnyWrap, Depth + 1),
2973 SCEV::FlagAnyWrap, Depth + 1);
2974 }
2975 }
2976 AddRecOps.push_back(Term);
2977 }
2978 if (!Overflow) {
2979 const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRec->getLoop(),
2980 SCEV::FlagAnyWrap);
2981 if (Ops.size() == 2) return NewAddRec;
2982 Ops[Idx] = NewAddRec;
2983 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2984 OpsModified = true;
2985 AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec);
2986 if (!AddRec)
2987 break;
2988 }
2989 }
2990 if (OpsModified)
2991 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2992
2993 // Otherwise couldn't fold anything into this recurrence. Move onto the
2994 // next one.
2995 }
2996
2997 // Okay, it looks like we really DO need an mul expr. Check to see if we
2998 // already have one, otherwise create a new one.
2999 return getOrCreateMulExpr(Ops, Flags);
3000}
3001
3002/// Represents an unsigned remainder expression based on unsigned division.
3003const SCEV *ScalarEvolution::getURemExpr(const SCEV *LHS,
3004 const SCEV *RHS) {
3005 assert(getEffectiveSCEVType(LHS->getType()) ==((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3007, __PRETTY_FUNCTION__))
3006 getEffectiveSCEVType(RHS->getType()) &&((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3007, __PRETTY_FUNCTION__))
3007 "SCEVURemExpr operand types don't match!")((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3007, __PRETTY_FUNCTION__))
;
3008
3009 // Short-circuit easy cases
3010 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3011 // If constant is one, the result is trivial
3012 if (RHSC->getValue()->isOne())
3013 return getZero(LHS->getType()); // X urem 1 --> 0
3014
3015 // If constant is a power of two, fold into a zext(trunc(LHS)).
3016 if (RHSC->getAPInt().isPowerOf2()) {
3017 Type *FullTy = LHS->getType();
3018 Type *TruncTy =
3019 IntegerType::get(getContext(), RHSC->getAPInt().logBase2());
3020 return getZeroExtendExpr(getTruncateExpr(LHS, TruncTy), FullTy);
3021 }
3022 }
3023
3024 // Fallback to %a == %x urem %y == %x -<nuw> ((%x udiv %y) *<nuw> %y)
3025 const SCEV *UDiv = getUDivExpr(LHS, RHS);
3026 const SCEV *Mult = getMulExpr(UDiv, RHS, SCEV::FlagNUW);
3027 return getMinusSCEV(LHS, Mult, SCEV::FlagNUW);
3028}
3029
3030/// Get a canonical unsigned division expression, or something simpler if
3031/// possible.
3032const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
3033 const SCEV *RHS) {
3034 assert(getEffectiveSCEVType(LHS->getType()) ==((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVUDivExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3036, __PRETTY_FUNCTION__))
3035 getEffectiveSCEVType(RHS->getType()) &&((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVUDivExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3036, __PRETTY_FUNCTION__))
3036 "SCEVUDivExpr operand types don't match!")((getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType
(RHS->getType()) && "SCEVUDivExpr operand types don't match!"
) ? static_cast<void> (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3036, __PRETTY_FUNCTION__))
;
3037
3038 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3039 if (RHSC->getValue()->isOne())
3040 return LHS; // X udiv 1 --> x
3041 // If the denominator is zero, the result of the udiv is undefined. Don't
3042 // try to analyze it, because the resolution chosen here may differ from
3043 // the resolution chosen in other parts of the compiler.
3044 if (!RHSC->getValue()->isZero()) {
3045 // Determine if the division can be folded into the operands of
3046 // its operands.
3047 // TODO: Generalize this to non-constants by using known-bits information.
3048 Type *Ty = LHS->getType();
3049 unsigned LZ = RHSC->getAPInt().countLeadingZeros();
3050 unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
3051 // For non-power-of-two values, effectively round the value up to the
3052 // nearest power of two.
3053 if (!RHSC->getAPInt().isPowerOf2())
3054 ++MaxShiftAmt;
3055 IntegerType *ExtTy =
3056 IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
3057 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
3058 if (const SCEVConstant *Step =
3059 dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) {
3060 // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
3061 const APInt &StepInt = Step->getAPInt();
3062 const APInt &DivInt = RHSC->getAPInt();
3063 if (!StepInt.urem(DivInt) &&
3064 getZeroExtendExpr(AR, ExtTy) ==
3065 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3066 getZeroExtendExpr(Step, ExtTy),
3067 AR->getLoop(), SCEV::FlagAnyWrap)) {
3068 SmallVector<const SCEV *, 4> Operands;
3069 for (const SCEV *Op : AR->operands())
3070 Operands.push_back(getUDivExpr(Op, RHS));
3071 return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW);
3072 }
3073 /// Get a canonical UDivExpr for a recurrence.
3074 /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0.
3075 // We can currently only fold X%N if X is constant.
3076 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
3077 if (StartC && !DivInt.urem(StepInt) &&
3078 getZeroExtendExpr(AR, ExtTy) ==
3079 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3080 getZeroExtendExpr(Step, ExtTy),
3081 AR->getLoop(), SCEV::FlagAnyWrap)) {
3082 const APInt &StartInt = StartC->getAPInt();
3083 const APInt &StartRem = StartInt.urem(StepInt);
3084 if (StartRem != 0)
3085 LHS = getAddRecExpr(getConstant(StartInt - StartRem), Step,
3086 AR->getLoop(), SCEV::FlagNW);
3087 }
3088 }
3089 // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
3090 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
3091 SmallVector<const SCEV *, 4> Operands;
3092 for (const SCEV *Op : M->operands())
3093 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3094 if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
3095 // Find an operand that's safely divisible.
3096 for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
3097 const SCEV *Op = M->getOperand(i);
3098 const SCEV *Div = getUDivExpr(Op, RHSC);
3099 if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
3100 Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
3101 M->op_end());
3102 Operands[i] = Div;
3103 return getMulExpr(Operands);
3104 }
3105 }
3106 }
3107 // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
3108 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
3109 SmallVector<const SCEV *, 4> Operands;
3110 for (const SCEV *Op : A->operands())
3111 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3112 if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
3113 Operands.clear();
3114 for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
3115 const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
3116 if (isa<SCEVUDivExpr>(Op) ||
3117 getMulExpr(Op, RHS) != A->getOperand(i))
3118 break;
3119 Operands.push_back(Op);
3120 }
3121 if (Operands.size() == A->getNumOperands())
3122 return getAddExpr(Operands);
3123 }
3124 }
3125
3126 // Fold if both operands are constant.
3127 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
3128 Constant *LHSCV = LHSC->getValue();
3129 Constant *RHSCV = RHSC->getValue();
3130 return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
3131 RHSCV)));
3132 }
3133 }
3134 }
3135
3136 FoldingSetNodeID ID;
3137 ID.AddInteger(scUDivExpr);
3138 ID.AddPointer(LHS);
3139 ID.AddPointer(RHS);
3140 void *IP = nullptr;
3141 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3142 SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
3143 LHS, RHS);
3144 UniqueSCEVs.InsertNode(S, IP);
3145 addToLoopUseLists(S);
3146 return S;
3147}
3148
3149static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {
3150 APInt A = C1->getAPInt().abs();
3151 APInt B = C2->getAPInt().abs();
3152 uint32_t ABW = A.getBitWidth();
3153 uint32_t BBW = B.getBitWidth();
3154
3155 if (ABW > BBW)
3156 B = B.zext(ABW);
3157 else if (ABW < BBW)
3158 A = A.zext(BBW);
3159
3160 return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B));
3161}
3162
3163/// Get a canonical unsigned division expression, or something simpler if
3164/// possible. There is no representation for an exact udiv in SCEV IR, but we
3165/// can attempt to remove factors from the LHS and RHS. We can't do this when
3166/// it's not exact because the udiv may be clearing bits.
3167const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS,
3168 const SCEV *RHS) {
3169 // TODO: we could try to find factors in all sorts of things, but for now we
3170 // just deal with u/exact (multiply, constant). See SCEVDivision towards the
3171 // end of this file for inspiration.
3172
3173 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS);
3174 if (!Mul || !Mul->hasNoUnsignedWrap())
3175 return getUDivExpr(LHS, RHS);
3176
3177 if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) {
3178 // If the mulexpr multiplies by a constant, then that constant must be the
3179 // first element of the mulexpr.
3180 if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3181 if (LHSCst == RHSCst) {
3182 SmallVector<const SCEV *, 2> Operands;
3183 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3184 return getMulExpr(Operands);
3185 }
3186
3187 // We can't just assume that LHSCst divides RHSCst cleanly, it could be
3188 // that there's a factor provided by one of the other terms. We need to
3189 // check.
3190 APInt Factor = gcd(LHSCst, RHSCst);
3191 if (!Factor.isIntN(1)) {
3192 LHSCst =
3193 cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor)));
3194 RHSCst =
3195 cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor)));
3196 SmallVector<const SCEV *, 2> Operands;
3197 Operands.push_back(LHSCst);
3198 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3199 LHS = getMulExpr(Operands);
3200 RHS = RHSCst;
3201 Mul = dyn_cast<SCEVMulExpr>(LHS);
3202 if (!Mul)
3203 return getUDivExactExpr(LHS, RHS);
3204 }
3205 }
3206 }
3207
3208 for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) {
3209 if (Mul->getOperand(i) == RHS) {
3210 SmallVector<const SCEV *, 2> Operands;
3211 Operands.append(Mul->op_begin(), Mul->op_begin() + i);
3212 Operands.append(Mul->op_begin() + i + 1, Mul->op_end());
3213 return getMulExpr(Operands);
3214 }
3215 }
3216
3217 return getUDivExpr(LHS, RHS);
3218}
3219
3220/// Get an add recurrence expression for the specified loop. Simplify the
3221/// expression as much as possible.
3222const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
3223 const Loop *L,
3224 SCEV::NoWrapFlags Flags) {
3225 SmallVector<const SCEV *, 4> Operands;
3226 Operands.push_back(Start);
3227 if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
3228 if (StepChrec->getLoop() == L) {
3229 Operands.append(StepChrec->op_begin(), StepChrec->op_end());
3230 return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
3231 }
3232
3233 Operands.push_back(Step);
3234 return getAddRecExpr(Operands, L, Flags);
3235}
3236
3237/// Get an add recurrence expression for the specified loop. Simplify the
3238/// expression as much as possible.
3239const SCEV *
3240ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
3241 const Loop *L, SCEV::NoWrapFlags Flags) {
3242 if (Operands.size() == 1) return Operands[0];
3243#ifndef NDEBUG
3244 Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
3245 for (unsigned i = 1, e = Operands.size(); i != e; ++i)
3246 assert(getEffectiveSCEVType(Operands[i]->getType()) == ETy &&((getEffectiveSCEVType(Operands[i]->getType()) == ETy &&
"SCEVAddRecExpr operand types don't match!") ? static_cast<
void> (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3247, __PRETTY_FUNCTION__))
3247 "SCEVAddRecExpr operand types don't match!")((getEffectiveSCEVType(Operands[i]->getType()) == ETy &&
"SCEVAddRecExpr operand types don't match!") ? static_cast<
void> (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3247, __PRETTY_FUNCTION__))
;
3248 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3249 assert(isLoopInvariant(Operands[i], L) &&((isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3250, __PRETTY_FUNCTION__))
3250 "SCEVAddRecExpr operand is not loop-invariant!")((isLoopInvariant(Operands[i], L) && "SCEVAddRecExpr operand is not loop-invariant!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3250, __PRETTY_FUNCTION__))
;
3251#endif
3252
3253 if (Operands.back()->isZero()) {
3254 Operands.pop_back();
3255 return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
3256 }
3257
3258 // It's tempting to want to call getMaxBackedgeTakenCount count here and
3259 // use that information to infer NUW and NSW flags. However, computing a
3260 // BE count requires calling getAddRecExpr, so we may not yet have a
3261 // meaningful BE count at this point (and if we don't, we'd be stuck
3262 // with a SCEVCouldNotCompute as the cached BE count).
3263
3264 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
3265
3266 // Canonicalize nested AddRecs in by nesting them in order of loop depth.
3267 if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
3268 const Loop *NestedLoop = NestedAR->getLoop();
3269 if (L->contains(NestedLoop)
3270 ? (L->getLoopDepth() < NestedLoop->getLoopDepth())
3271 : (!NestedLoop->contains(L) &&
3272 DT.dominates(L->getHeader(), NestedLoop->getHeader()))) {
3273 SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(),
3274 NestedAR->op_end());
3275 Operands[0] = NestedAR->getStart();
3276 // AddRecs require their operands be loop-invariant with respect to their
3277 // loops. Don't perform this transformation if it would break this
3278 // requirement.
3279 bool AllInvariant = all_of(
3280 Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); });
3281
3282 if (AllInvariant) {
3283 // Create a recurrence for the outer loop with the same step size.
3284 //
3285 // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
3286 // inner recurrence has the same property.
3287 SCEV::NoWrapFlags OuterFlags =
3288 maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
3289
3290 NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
3291 AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) {
3292 return isLoopInvariant(Op, NestedLoop);
3293 });
3294
3295 if (AllInvariant) {
3296 // Ok, both add recurrences are valid after the transformation.
3297 //
3298 // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
3299 // the outer recurrence has the same property.
3300 SCEV::NoWrapFlags InnerFlags =
3301 maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
3302 return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
3303 }
3304 }
3305 // Reset Operands to its original state.
3306 Operands[0] = NestedAR;
3307 }
3308 }
3309
3310 // Okay, it looks like we really DO need an addrec expr. Check to see if we
3311 // already have one, otherwise create a new one.
3312 FoldingSetNodeID ID;
3313 ID.AddInteger(scAddRecExpr);
3314 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3315 ID.AddPointer(Operands[i]);
3316 ID.AddPointer(L);
3317 void *IP = nullptr;
3318 SCEVAddRecExpr *S =
3319 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
3320 if (!S) {
3321 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Operands.size());
3322 std::uninitialized_copy(Operands.begin(), Operands.end(), O);
3323 S = new (SCEVAllocator) SCEVAddRecExpr(ID.Intern(SCEVAllocator),
3324 O, Operands.size(), L);
3325 UniqueSCEVs.InsertNode(S, IP);
3326 addToLoopUseLists(S);
3327 }
3328 S->setNoWrapFlags(Flags);
3329 return S;
3330}
3331
3332const SCEV *
3333ScalarEvolution::getGEPExpr(GEPOperator *GEP,
3334 const SmallVectorImpl<const SCEV *> &IndexExprs) {
3335 const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand());
3336 // getSCEV(Base)->getType() has the same address space as Base->getType()
3337 // because SCEV::getType() preserves the address space.
3338 Type *IntPtrTy = getEffectiveSCEVType(BaseExpr->getType());
3339 // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP
3340 // instruction to its SCEV, because the Instruction may be guarded by control
3341 // flow and the no-overflow bits may not be valid for the expression in any
3342 // context. This can be fixed similarly to how these flags are handled for
3343 // adds.
3344 SCEV::NoWrapFlags Wrap = GEP->isInBounds() ? SCEV::FlagNSW
3345 : SCEV::FlagAnyWrap;
3346
3347 const SCEV *TotalOffset = getZero(IntPtrTy);
3348 // The array size is unimportant. The first thing we do on CurTy is getting
3349 // its element type.
3350 Type *CurTy = ArrayType::get(GEP->getSourceElementType(), 0);
3351 for (const SCEV *IndexExpr : IndexExprs) {
3352 // Compute the (potentially symbolic) offset in bytes for this index.
3353 if (StructType *STy = dyn_cast<StructType>(CurTy)) {
3354 // For a struct, add the member offset.
3355 ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue();
3356 unsigned FieldNo = Index->getZExtValue();
3357 const SCEV *FieldOffset = getOffsetOfExpr(IntPtrTy, STy, FieldNo);
3358
3359 // Add the field offset to the running total offset.
3360 TotalOffset = getAddExpr(TotalOffset, FieldOffset);
3361
3362 // Update CurTy to the type of the field at Index.
3363 CurTy = STy->getTypeAtIndex(Index);
3364 } else {
3365 // Update CurTy to its element type.
3366 CurTy = cast<SequentialType>(CurTy)->getElementType();
3367 // For an array, add the element offset, explicitly scaled.
3368 const SCEV *ElementSize = getSizeOfExpr(IntPtrTy, CurTy);
3369 // Getelementptr indices are signed.
3370 IndexExpr = getTruncateOrSignExtend(IndexExpr, IntPtrTy);
3371
3372 // Multiply the index by the element size to compute the element offset.
3373 const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, Wrap);
3374
3375 // Add the element offset to the running total offset.
3376 TotalOffset = getAddExpr(TotalOffset, LocalOffset);
3377 }
3378 }
3379
3380 // Add the total offset from all the GEP indices to the base.
3381 return getAddExpr(BaseExpr, TotalOffset, Wrap);
3382}
3383
3384const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS,
3385 const SCEV *RHS) {
3386 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3387 return getSMaxExpr(Ops);
3388}
3389
3390const SCEV *
3391ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3392 assert(!Ops.empty() && "Cannot get empty smax!")((!Ops.empty() && "Cannot get empty smax!") ? static_cast
<void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty smax!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3392, __PRETTY_FUNCTION__))
;
3393 if (Ops.size() == 1) return Ops[0];
3394#ifndef NDEBUG
3395 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3396 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3397 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVSMaxExpr operand types don't match!") ? static_cast<
void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVSMaxExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3398, __PRETTY_FUNCTION__))
3398 "SCEVSMaxExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVSMaxExpr operand types don't match!") ? static_cast<
void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVSMaxExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3398, __PRETTY_FUNCTION__))
;
3399#endif
3400
3401 // Sort by complexity, this groups all similar expression types together.
3402 GroupByComplexity(Ops, &LI, DT);
3403
3404 // If there are any constants, fold them together.
3405 unsigned Idx = 0;
3406 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3407 ++Idx;
3408 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3408, __PRETTY_FUNCTION__))
;
3409 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3410 // We found two constants, fold them together!
3411 ConstantInt *Fold = ConstantInt::get(
3412 getContext(), APIntOps::smax(LHSC->getAPInt(), RHSC->getAPInt()));
3413 Ops[0] = getConstant(Fold);
3414 Ops.erase(Ops.begin()+1); // Erase the folded element
3415 if (Ops.size() == 1) return Ops[0];
3416 LHSC = cast<SCEVConstant>(Ops[0]);
3417 }
3418
3419 // If we are left with a constant minimum-int, strip it off.
3420 if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) {
3421 Ops.erase(Ops.begin());
3422 --Idx;
3423 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(true)) {
3424 // If we have an smax with a constant maximum-int, it will always be
3425 // maximum-int.
3426 return Ops[0];
3427 }
3428
3429 if (Ops.size() == 1) return Ops[0];
3430 }
3431
3432 // Find the first SMax
3433 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scSMaxExpr)
3434 ++Idx;
3435
3436 // Check to see if one of the operands is an SMax. If so, expand its operands
3437 // onto our operand list, and recurse to simplify.
3438 if (Idx < Ops.size()) {
3439 bool DeletedSMax = false;
3440 while (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(Ops[Idx])) {
3441 Ops.erase(Ops.begin()+Idx);
3442 Ops.append(SMax->op_begin(), SMax->op_end());
3443 DeletedSMax = true;
3444 }
3445
3446 if (DeletedSMax)
3447 return getSMaxExpr(Ops);
3448 }
3449
3450 // Okay, check to see if the same value occurs in the operand list twice. If
3451 // so, delete one. Since we sorted the list, these values are required to
3452 // be adjacent.
3453 for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
3454 // X smax Y smax Y --> X smax Y
3455 // X smax Y --> X, if X is always greater than Y
3456 if (Ops[i] == Ops[i+1] ||
3457 isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) {
3458 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
3459 --i; --e;
3460 } else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) {
3461 Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
3462 --i; --e;
3463 }
3464
3465 if (Ops.size() == 1) return Ops[0];
3466
3467 assert(!Ops.empty() && "Reduced smax down to nothing!")((!Ops.empty() && "Reduced smax down to nothing!") ? static_cast
<void> (0) : __assert_fail ("!Ops.empty() && \"Reduced smax down to nothing!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3467, __PRETTY_FUNCTION__))
;
3468
3469 // Okay, it looks like we really DO need an smax expr. Check to see if we
3470 // already have one, otherwise create a new one.
3471 FoldingSetNodeID ID;
3472 ID.AddInteger(scSMaxExpr);
3473 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3474 ID.AddPointer(Ops[i]);
3475 void *IP = nullptr;
3476 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3477 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3478 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3479 SCEV *S = new (SCEVAllocator) SCEVSMaxExpr(ID.Intern(SCEVAllocator),
3480 O, Ops.size());
3481 UniqueSCEVs.InsertNode(S, IP);
3482 addToLoopUseLists(S);
3483 return S;
3484}
3485
3486const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS,
3487 const SCEV *RHS) {
3488 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3489 return getUMaxExpr(Ops);
3490}
3491
3492const SCEV *
3493ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3494 assert(!Ops.empty() && "Cannot get empty umax!")((!Ops.empty() && "Cannot get empty umax!") ? static_cast
<void> (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty umax!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3494, __PRETTY_FUNCTION__))
;
3495 if (Ops.size() == 1) return Ops[0];
3496#ifndef NDEBUG
3497 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3498 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3499 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVUMaxExpr operand types don't match!") ? static_cast<
void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVUMaxExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3500, __PRETTY_FUNCTION__))
3500 "SCEVUMaxExpr operand types don't match!")((getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
"SCEVUMaxExpr operand types don't match!") ? static_cast<
void> (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVUMaxExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3500, __PRETTY_FUNCTION__))
;
3501#endif
3502
3503 // Sort by complexity, this groups all similar expression types together.
3504 GroupByComplexity(Ops, &LI, DT);
3505
3506 // If there are any constants, fold them together.
3507 unsigned Idx = 0;
3508 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3509 ++Idx;
3510 assert(Idx < Ops.size())((Idx < Ops.size()) ? static_cast<void> (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3510, __PRETTY_FUNCTION__))
;
3511 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3512 // We found two constants, fold them together!
3513 ConstantInt *Fold = ConstantInt::get(
3514 getContext(), APIntOps::umax(LHSC->getAPInt(), RHSC->getAPInt()));
3515 Ops[0] = getConstant(Fold);
3516 Ops.erase(Ops.begin()+1); // Erase the folded element
3517 if (Ops.size() == 1) return Ops[0];
3518 LHSC = cast<SCEVConstant>(Ops[0]);
3519 }
3520
3521 // If we are left with a constant minimum-int, strip it off.
3522 if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) {
3523 Ops.erase(Ops.begin());
3524 --Idx;
3525 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(false)) {
3526 // If we have an umax with a constant maximum-int, it will always be
3527 // maximum-int.
3528 return Ops[0];
3529 }
3530
3531 if (Ops.size() == 1) return Ops[0];
3532 }
3533
3534 // Find the first UMax
3535 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scUMaxExpr)
3536 ++Idx;
3537
3538 // Check to see if one of the operands is a UMax. If so, expand its operands
3539 // onto our operand list, and recurse to simplify.
3540 if (Idx < Ops.size()) {
3541 bool DeletedUMax = false;
3542 while (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(Ops[Idx])) {
3543 Ops.erase(Ops.begin()+Idx);
3544 Ops.append(UMax->op_begin(), UMax->op_end());
3545 DeletedUMax = true;
3546 }
3547
3548 if (DeletedUMax)
3549 return getUMaxExpr(Ops);
3550 }
3551
3552 // Okay, check to see if the same value occurs in the operand list twice. If
3553 // so, delete one. Since we sorted the list, these values are required to
3554 // be adjacent.
3555 for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
3556 // X umax Y umax Y --> X umax Y
3557 // X umax Y --> X, if X is always greater than Y
3558 if (Ops[i] == Ops[i+1] ||
3559 isKnownPredicate(ICmpInst::ICMP_UGE, Ops[i], Ops[i+1])) {
3560 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
3561 --i; --e;
3562 } else if (isKnownPredicate(ICmpInst::ICMP_ULE, Ops[i], Ops[i+1])) {
3563 Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
3564 --i; --e;
3565 }
3566
3567 if (Ops.size() == 1) return Ops[0];
3568
3569 assert(!Ops.empty() && "Reduced umax down to nothing!")((!Ops.empty() && "Reduced umax down to nothing!") ? static_cast
<void> (0) : __assert_fail ("!Ops.empty() && \"Reduced umax down to nothing!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3569, __PRETTY_FUNCTION__))
;
3570
3571 // Okay, it looks like we really DO need a umax expr. Check to see if we
3572 // already have one, otherwise create a new one.
3573 FoldingSetNodeID ID;
3574 ID.AddInteger(scUMaxExpr);
3575 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3576 ID.AddPointer(Ops[i]);
3577 void *IP = nullptr;
3578 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3579 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3580 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3581 SCEV *S = new (SCEVAllocator) SCEVUMaxExpr(ID.Intern(SCEVAllocator),
3582 O, Ops.size());
3583 UniqueSCEVs.InsertNode(S, IP);
3584 addToLoopUseLists(S);
3585 return S;
3586}
3587
3588const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
3589 const SCEV *RHS) {
3590 // ~smax(~x, ~y) == smin(x, y).
3591 return getNotSCEV(getSMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
3592}
3593
3594const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
3595 const SCEV *RHS) {
3596 // ~umax(~x, ~y) == umin(x, y)
3597 return getNotSCEV(getUMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
3598}
3599
3600const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) {
3601 // We can bypass creating a target-independent
3602 // constant expression and then folding it back into a ConstantInt.
3603 // This is just a compile-time optimization.
3604 return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy));
3605}
3606
3607const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy,
3608 StructType *STy,
3609 unsigned FieldNo) {
3610 // We can bypass creating a target-independent
3611 // constant expression and then folding it back into a ConstantInt.
3612 // This is just a compile-time optimization.
3613 return getConstant(
3614 IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo));
3615}
3616
3617const SCEV *ScalarEvolution::getUnknown(Value *V) {
3618 // Don't attempt to do anything other than create a SCEVUnknown object
3619 // here. createSCEV only calls getUnknown after checking for all other
3620 // interesting possibilities, and any other code that calls getUnknown
3621 // is doing so in order to hide a value from SCEV canonicalization.
3622
3623 FoldingSetNodeID ID;
3624 ID.AddInteger(scUnknown);
3625 ID.AddPointer(V);
3626 void *IP = nullptr;
3627 if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
3628 assert(cast<SCEVUnknown>(S)->getValue() == V &&((cast<SCEVUnknown>(S)->getValue() == V && "Stale SCEVUnknown in uniquing map!"
) ? static_cast<void> (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3629, __PRETTY_FUNCTION__))
3629 "Stale SCEVUnknown in uniquing map!")((cast<SCEVUnknown>(S)->getValue() == V && "Stale SCEVUnknown in uniquing map!"
) ? static_cast<void> (0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3629, __PRETTY_FUNCTION__))
;
3630 return S;
3631 }
3632 SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
3633 FirstUnknown);
3634 FirstUnknown = cast<SCEVUnknown>(S);
3635 UniqueSCEVs.InsertNode(S, IP);
3636 return S;
3637}
3638
3639//===----------------------------------------------------------------------===//
3640// Basic SCEV Analysis and PHI Idiom Recognition Code
3641//
3642
3643/// Test if values of the given type are analyzable within the SCEV
3644/// framework. This primarily includes integer types, and it can optionally
3645/// include pointer types if the ScalarEvolution class has access to
3646/// target-specific information.
3647bool ScalarEvolution::isSCEVable(Type *Ty) const {
3648 // Integers and pointers are always SCEVable.
3649 return Ty->isIntegerTy() || Ty->isPointerTy();
3650}
3651
3652/// Return the size in bits of the specified type, for which isSCEVable must
3653/// return true.
3654uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
3655 assert(isSCEVable(Ty) && "Type is not SCEVable!")((isSCEVable(Ty) && "Type is not SCEVable!") ? static_cast
<void> (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3655, __PRETTY_FUNCTION__))
;
3656 return getDataLayout().getTypeSizeInBits(Ty);
3657}
3658
3659/// Return a type with the same bitwidth as the given type and which represents
3660/// how SCEV will treat the given type, for which isSCEVable must return
3661/// true. For pointer types, this is the pointer-sized integer type.
3662Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
3663 assert(isSCEVable(Ty) && "Type is not SCEVable!")((isSCEVable(Ty) && "Type is not SCEVable!") ? static_cast
<void> (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3663, __PRETTY_FUNCTION__))
;
3664
3665 if (Ty->isIntegerTy())
3666 return Ty;
3667
3668 // The only other support type is pointer.
3669 assert(Ty->isPointerTy() && "Unexpected non-pointer non-integer type!")((Ty->isPointerTy() && "Unexpected non-pointer non-integer type!"
) ? static_cast<void> (0) : __assert_fail ("Ty->isPointerTy() && \"Unexpected non-pointer non-integer type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3669, __PRETTY_FUNCTION__))
;
3670 return getDataLayout().getIntPtrType(Ty);
3671}
3672
3673Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const {
3674 return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2;
3675}
3676
3677const SCEV *ScalarEvolution::getCouldNotCompute() {
3678 return CouldNotCompute.get();
3679}
3680
3681bool ScalarEvolution::checkValidity(const SCEV *S) const {
3682 bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) {
3683 auto *SU = dyn_cast<SCEVUnknown>(S);
3684 return SU && SU->getValue() == nullptr;
3685 });
3686
3687 return !ContainsNulls;
3688}
3689
3690bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
3691 HasRecMapType::iterator I = HasRecMap.find(S);
3692 if (I != HasRecMap.end())
3693 return I->second;
3694
3695 bool FoundAddRec = SCEVExprContains(S, isa<SCEVAddRecExpr, const SCEV *>);
3696 HasRecMap.insert({S, FoundAddRec});
3697 return FoundAddRec;
3698}
3699
3700/// Try to split a SCEVAddExpr into a pair of {SCEV, ConstantInt}.
3701/// If \p S is a SCEVAddExpr and is composed of a sub SCEV S' and an
3702/// offset I, then return {S', I}, else return {\p S, nullptr}.
3703static std::pair<const SCEV *, ConstantInt *> splitAddExpr(const SCEV *S) {
3704 const auto *Add = dyn_cast<SCEVAddExpr>(S);
3705 if (!Add)
3706 return {S, nullptr};
3707
3708 if (Add->getNumOperands() != 2)
3709 return {S, nullptr};
3710
3711 auto *ConstOp = dyn_cast<SCEVConstant>(Add->getOperand(0));
3712 if (!ConstOp)
3713 return {S, nullptr};
3714
3715 return {Add->getOperand(1), ConstOp->getValue()};
3716}
3717
3718/// Return the ValueOffsetPair set for \p S. \p S can be represented
3719/// by the value and offset from any ValueOffsetPair in the set.
3720SetVector<ScalarEvolution::ValueOffsetPair> *
3721ScalarEvolution::getSCEVValues(const SCEV *S) {
3722 ExprValueMapType::iterator SI = ExprValueMap.find_as(S);
3723 if (SI == ExprValueMap.end())
3724 return nullptr;
3725#ifndef NDEBUG
3726 if (VerifySCEVMap) {
3727 // Check there is no dangling Value in the set returned.
3728 for (const auto &VE : SI->second)
3729 assert(ValueExprMap.count(VE.first))((ValueExprMap.count(VE.first)) ? static_cast<void> (0)
: __assert_fail ("ValueExprMap.count(VE.first)", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3729, __PRETTY_FUNCTION__))
;
3730 }
3731#endif
3732 return &SI->second;
3733}
3734
3735/// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V)
3736/// cannot be used separately. eraseValueFromMap should be used to remove
3737/// V from ValueExprMap and ExprValueMap at the same time.
3738void ScalarEvolution::eraseValueFromMap(Value *V) {
3739 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3740 if (I != ValueExprMap.end()) {
3741 const SCEV *S = I->second;
3742 // Remove {V, 0} from the set of ExprValueMap[S]
3743 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(S))
3744 SV->remove({V, nullptr});
3745
3746 // Remove {V, Offset} from the set of ExprValueMap[Stripped]
3747 const SCEV *Stripped;
3748 ConstantInt *Offset;
3749 std::tie(Stripped, Offset) = splitAddExpr(S);
3750 if (Offset != nullptr) {
3751 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(Stripped))
3752 SV->remove({V, Offset});
3753 }
3754 ValueExprMap.erase(V);
3755 }
3756}
3757
3758/// Return an existing SCEV if it exists, otherwise analyze the expression and
3759/// create a new one.
3760const SCEV *ScalarEvolution::getSCEV(Value *V) {
3761 assert(isSCEVable(V->getType()) && "Value is not SCEVable!")((isSCEVable(V->getType()) && "Value is not SCEVable!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3761, __PRETTY_FUNCTION__))
;
3762
3763 const SCEV *S = getExistingSCEV(V);
3764 if (S == nullptr) {
3765 S = createSCEV(V);
3766 // During PHI resolution, it is possible to create two SCEVs for the same
3767 // V, so it is needed to double check whether V->S is inserted into
3768 // ValueExprMap before insert S->{V, 0} into ExprValueMap.
3769 std::pair<ValueExprMapType::iterator, bool> Pair =
3770 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
3771 if (Pair.second) {
3772 ExprValueMap[S].insert({V, nullptr});
3773
3774 // If S == Stripped + Offset, add Stripped -> {V, Offset} into
3775 // ExprValueMap.
3776 const SCEV *Stripped = S;
3777 ConstantInt *Offset = nullptr;
3778 std::tie(Stripped, Offset) = splitAddExpr(S);
3779 // If stripped is SCEVUnknown, don't bother to save
3780 // Stripped -> {V, offset}. It doesn't simplify and sometimes even
3781 // increase the complexity of the expansion code.
3782 // If V is GetElementPtrInst, don't save Stripped -> {V, offset}
3783 // because it may generate add/sub instead of GEP in SCEV expansion.
3784 if (Offset != nullptr && !isa<SCEVUnknown>(Stripped) &&
3785 !isa<GetElementPtrInst>(V))
3786 ExprValueMap[Stripped].insert({V, Offset});
3787 }
3788 }
3789 return S;
3790}
3791
3792const SCEV *ScalarEvolution::getExistingSCEV(Value *V) {
3793 assert(isSCEVable(V->getType()) && "Value is not SCEVable!")((isSCEVable(V->getType()) && "Value is not SCEVable!"
) ? static_cast<void> (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3793, __PRETTY_FUNCTION__))
;
3794
3795 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3796 if (I != ValueExprMap.end()) {
3797 const SCEV *S = I->second;
3798 if (checkValidity(S))
3799 return S;
3800 eraseValueFromMap(V);
3801 forgetMemoizedResults(S);
3802 }
3803 return nullptr;
3804}
3805
3806/// Return a SCEV corresponding to -V = -1*V
3807const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V,
3808 SCEV::NoWrapFlags Flags) {
3809 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3810 return getConstant(
3811 cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
3812
3813 Type *Ty = V->getType();
3814 Ty = getEffectiveSCEVType(Ty);
3815 return getMulExpr(
3816 V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags);
3817}
3818
3819/// Return a SCEV corresponding to ~V = -1-V
3820const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
3821 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3822 return getConstant(
3823 cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
3824
3825 Type *Ty = V->getType();
3826 Ty = getEffectiveSCEVType(Ty);
3827 const SCEV *AllOnes =
3828 getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)));
3829 return getMinusSCEV(AllOnes, V);
3830}
3831
3832const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
3833 SCEV::NoWrapFlags Flags,
3834 unsigned Depth) {
3835 // Fast path: X - X --> 0.
3836 if (LHS == RHS)
3837 return getZero(LHS->getType());
3838
3839 // We represent LHS - RHS as LHS + (-1)*RHS. This transformation
3840 // makes it so that we cannot make much use of NUW.
3841 auto AddFlags = SCEV::FlagAnyWrap;
3842 const bool RHSIsNotMinSigned =
3843 !getSignedRangeMin(RHS).isMinSignedValue();
3844 if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) {
3845 // Let M be the minimum representable signed value. Then (-1)*RHS
3846 // signed-wraps if and only if RHS is M. That can happen even for
3847 // a NSW subtraction because e.g. (-1)*M signed-wraps even though
3848 // -1 - M does not. So to transfer NSW from LHS - RHS to LHS +
3849 // (-1)*RHS, we need to prove that RHS != M.
3850 //
3851 // If LHS is non-negative and we know that LHS - RHS does not
3852 // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap
3853 // either by proving that RHS > M or that LHS >= 0.
3854 if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) {
3855 AddFlags = SCEV::FlagNSW;
3856 }
3857 }
3858
3859 // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS -
3860 // RHS is NSW and LHS >= 0.
3861 //
3862 // The difficulty here is that the NSW flag may have been proven
3863 // relative to a loop that is to be found in a recurrence in LHS and
3864 // not in RHS. Applying NSW to (-1)*M may then let the NSW have a
3865 // larger scope than intended.
3866 auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
3867
3868 return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth);
3869}
3870
3871const SCEV *
3872ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty) {
3873 Type *SrcTy = V->getType();
3874 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3876, __PRETTY_FUNCTION__))
3875 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3876, __PRETTY_FUNCTION__))
3876 "Cannot truncate or zero extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3876, __PRETTY_FUNCTION__))
;
3877 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3878 return V; // No conversion
3879 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3880 return getTruncateExpr(V, Ty);
3881 return getZeroExtendExpr(V, Ty);
3882}
3883
3884const SCEV *
3885ScalarEvolution::getTruncateOrSignExtend(const SCEV *V,
3886 Type *Ty) {
3887 Type *SrcTy = V->getType();
3888 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3890, __PRETTY_FUNCTION__))
3889 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3890, __PRETTY_FUNCTION__))
3890 "Cannot truncate or zero extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3890, __PRETTY_FUNCTION__))
;
3891 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3892 return V; // No conversion
3893 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3894 return getTruncateExpr(V, Ty);
3895 return getSignExtendExpr(V, Ty);
3896}
3897
3898const SCEV *
3899ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
3900 Type *SrcTy = V->getType();
3901 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3903, __PRETTY_FUNCTION__))
3902 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3903, __PRETTY_FUNCTION__))
3903 "Cannot noop or zero extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or zero extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or zero extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3903, __PRETTY_FUNCTION__))
;
3904 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrZeroExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3905, __PRETTY_FUNCTION__))
3905 "getNoopOrZeroExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrZeroExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3905, __PRETTY_FUNCTION__))
;
3906 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3907 return V; // No conversion
3908 return getZeroExtendExpr(V, Ty);
3909}
3910
3911const SCEV *
3912ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
3913 Type *SrcTy = V->getType();
3914 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or sign extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or sign extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3916, __PRETTY_FUNCTION__))
3915 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or sign extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or sign extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3916, __PRETTY_FUNCTION__))
3916 "Cannot noop or sign extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or sign extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or sign extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3916, __PRETTY_FUNCTION__))
;
3917 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrSignExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3918, __PRETTY_FUNCTION__))
3918 "getNoopOrSignExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrSignExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3918, __PRETTY_FUNCTION__))
;
3919 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3920 return V; // No conversion
3921 return getSignExtendExpr(V, Ty);
3922}
3923
3924const SCEV *
3925ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
3926 Type *SrcTy = V->getType();
3927 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or any extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or any extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3929, __PRETTY_FUNCTION__))
3928 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or any extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or any extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3929, __PRETTY_FUNCTION__))
3929 "Cannot noop or any extend with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot noop or any extend with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot noop or any extend with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3929, __PRETTY_FUNCTION__))
;
3930 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrAnyExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3931, __PRETTY_FUNCTION__))
3931 "getNoopOrAnyExtend cannot truncate!")((getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
"getNoopOrAnyExtend cannot truncate!") ? static_cast<void
> (0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3931, __PRETTY_FUNCTION__))
;
3932 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3933 return V; // No conversion
3934 return getAnyExtendExpr(V, Ty);
3935}
3936
3937const SCEV *
3938ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
3939 Type *SrcTy = V->getType();
3940 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or noop with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3942, __PRETTY_FUNCTION__))
3941 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or noop with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3942, __PRETTY_FUNCTION__))
3942 "Cannot truncate or noop with non-integer arguments!")(((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
(Ty->isIntegerTy() || Ty->isPointerTy()) && "Cannot truncate or noop with non-integer arguments!"
) ? static_cast<void> (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3942, __PRETTY_FUNCTION__))
;
3943 assert(getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&
"getTruncateOrNoop cannot extend!") ? static_cast<void>
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3944, __PRETTY_FUNCTION__))
3944 "getTruncateOrNoop cannot extend!")((getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&
"getTruncateOrNoop cannot extend!") ? static_cast<void>
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 3944, __PRETTY_FUNCTION__))
;
3945 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3946 return V; // No conversion
3947 return getTruncateExpr(V, Ty);
3948}
3949
3950const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
3951 const SCEV *RHS) {
3952 const SCEV *PromotedLHS = LHS;
3953 const SCEV *PromotedRHS = RHS;
3954
3955 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3956 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3957 else
3958 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3959
3960 return getUMaxExpr(PromotedLHS, PromotedRHS);
3961}
3962
3963const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
3964 const SCEV *RHS) {
3965 const SCEV *PromotedLHS = LHS;
3966 const SCEV *PromotedRHS = RHS;
3967
3968 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3969 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3970 else
3971 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3972
3973 return getUMinExpr(PromotedLHS, PromotedRHS);
3974}
3975
3976const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
3977 // A pointer operand may evaluate to a nonpointer expression, such as null.
3978 if (!V->getType()->isPointerTy())
3979 return V;
3980
3981 if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) {
3982 return getPointerBase(Cast->getOperand());
3983 } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) {
3984 const SCEV *PtrOp = nullptr;
3985 for (const SCEV *NAryOp : NAry->operands()) {
3986 if (NAryOp->getType()->isPointerTy()) {
3987 // Cannot find the base of an expression with multiple pointer operands.
3988 if (PtrOp)
3989 return V;
3990 PtrOp = NAryOp;
3991 }
3992 }
3993 if (!PtrOp)
3994 return V;
3995 return getPointerBase(PtrOp);
3996 }
3997 return V;
3998}
3999
4000/// Push users of the given Instruction onto the given Worklist.
4001static void
4002PushDefUseChildren(Instruction *I,
4003 SmallVectorImpl<Instruction *> &Worklist) {
4004 // Push the def-use children onto the Worklist stack.
4005 for (User *U : I->users())
4006 Worklist.push_back(cast<Instruction>(U));
4007}
4008
4009void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) {
4010 SmallVector<Instruction *, 16> Worklist;
4011 PushDefUseChildren(PN, Worklist);
4012
4013 SmallPtrSet<Instruction *, 8> Visited;
4014 Visited.insert(PN);
4015 while (!Worklist.empty()) {
4016 Instruction *I = Worklist.pop_back_val();
4017 if (!Visited.insert(I).second)
4018 continue;
4019
4020 auto It = ValueExprMap.find_as(static_cast<Value *>(I));
4021 if (It != ValueExprMap.end()) {
4022 const SCEV *Old = It->second;
4023
4024 // Short-circuit the def-use traversal if the symbolic name
4025 // ceases to appear in expressions.
4026 if (Old != SymName && !hasOperand(Old, SymName))
4027 continue;
4028
4029 // SCEVUnknown for a PHI either means that it has an unrecognized
4030 // structure, it's a PHI that's in the progress of being computed
4031 // by createNodeForPHI, or it's a single-value PHI. In the first case,
4032 // additional loop trip count information isn't going to change anything.
4033 // In the second case, createNodeForPHI will perform the necessary
4034 // updates on its own when it gets to that point. In the third, we do
4035 // want to forget the SCEVUnknown.
4036 if (!isa<PHINode>(I) ||
4037 !isa<SCEVUnknown>(Old) ||
4038 (I != PN && Old == SymName)) {
4039 eraseValueFromMap(It->first);
4040 forgetMemoizedResults(Old);
4041 }
4042 }
4043
4044 PushDefUseChildren(I, Worklist);
4045 }
4046}
4047
4048namespace {
4049
4050class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
4051public:
4052 SCEVInitRewriter(const Loop *L, ScalarEvolution &SE)
4053 : SCEVRewriteVisitor(SE), L(L) {}
4054
4055 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4056 ScalarEvolution &SE) {
4057 SCEVInitRewriter Rewriter(L, SE);
4058 const SCEV *Result = Rewriter.visit(S);
4059 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
4060 }
4061
4062 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4063 if (!SE.isLoopInvariant(Expr, L))
4064 Valid = false;
4065 return Expr;
4066 }
4067
4068 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4069 // Only allow AddRecExprs for this loop.
4070 if (Expr->getLoop() == L)
4071 return Expr->getStart();
4072 Valid = false;
4073 return Expr;
4074 }
4075
4076 bool isValid() { return Valid; }
4077
4078private:
4079 const Loop *L;
4080 bool Valid = true;
4081};
4082
4083class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
4084public:
4085 SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE)
4086 : SCEVRewriteVisitor(SE), L(L) {}
4087
4088 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4089 ScalarEvolution &SE) {
4090 SCEVShiftRewriter Rewriter(L, SE);
4091 const SCEV *Result = Rewriter.visit(S);
4092 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
4093 }
4094
4095 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4096 // Only allow AddRecExprs for this loop.
4097 if (!SE.isLoopInvariant(Expr, L))
4098 Valid = false;
4099 return Expr;
4100 }
4101
4102 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4103 if (Expr->getLoop() == L && Expr->isAffine())
4104 return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE));
4105 Valid = false;
4106 return Expr;
4107 }
4108
4109 bool isValid() { return Valid; }
4110
4111private:
4112 const Loop *L;
4113 bool Valid = true;
4114};
4115
4116} // end anonymous namespace
4117
4118SCEV::NoWrapFlags
4119ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
4120 if (!AR->isAffine())
4121 return SCEV::FlagAnyWrap;
4122
4123 using OBO = OverflowingBinaryOperator;
4124
4125 SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
4126
4127 if (!AR->hasNoSignedWrap()) {
4128 ConstantRange AddRecRange = getSignedRange(AR);
4129 ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
4130
4131 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4132 Instruction::Add, IncRange, OBO::NoSignedWrap);
4133 if (NSWRegion.contains(AddRecRange))
4134 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
4135 }
4136
4137 if (!AR->hasNoUnsignedWrap()) {
4138 ConstantRange AddRecRange = getUnsignedRange(AR);
4139 ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
4140
4141 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4142 Instruction::Add, IncRange, OBO::NoUnsignedWrap);
4143 if (NUWRegion.contains(AddRecRange))
4144 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
4145 }
4146
4147 return Result;
4148}
4149
4150namespace {
4151
4152/// Represents an abstract binary operation. This may exist as a
4153/// normal instruction or constant expression, or may have been
4154/// derived from an expression tree.
4155struct BinaryOp {
4156 unsigned Opcode;
4157 Value *LHS;
4158 Value *RHS;
4159 bool IsNSW = false;
4160 bool IsNUW = false;
4161
4162 /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or
4163 /// constant expression.
4164 Operator *Op = nullptr;
4165
4166 explicit BinaryOp(Operator *Op)
4167 : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)),
4168 Op(Op) {
4169 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) {
4170 IsNSW = OBO->hasNoSignedWrap();
4171 IsNUW = OBO->hasNoUnsignedWrap();
4172 }
4173 }
4174
4175 explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false,
4176 bool IsNUW = false)
4177 : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW) {}
4178};
4179
4180} // end anonymous namespace
4181
4182/// Try to map \p V into a BinaryOp, and return \c None on failure.
4183static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) {
4184 auto *Op = dyn_cast<Operator>(V);
4185 if (!Op)
4186 return None;
4187
4188 // Implementation detail: all the cleverness here should happen without
4189 // creating new SCEV expressions -- our caller knowns tricks to avoid creating
4190 // SCEV expressions when possible, and we should not break that.
4191
4192 switch (Op->getOpcode()) {
4193 case Instruction::Add:
4194 case Instruction::Sub:
4195 case Instruction::Mul:
4196 case Instruction::UDiv:
4197 case Instruction::URem:
4198 case Instruction::And:
4199 case Instruction::Or:
4200 case Instruction::AShr:
4201 case Instruction::Shl:
4202 return BinaryOp(Op);
4203
4204 case Instruction::Xor:
4205 if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1)))
4206 // If the RHS of the xor is a signmask, then this is just an add.
4207 // Instcombine turns add of signmask into xor as a strength reduction step.
4208 if (RHSC->getValue().isSignMask())
4209 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
4210 return BinaryOp(Op);
4211
4212 case Instruction::LShr:
4213 // Turn logical shift right of a constant into a unsigned divide.
4214 if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) {
4215 uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth();
4216
4217 // If the shift count is not less than the bitwidth, the result of
4218 // the shift is undefined. Don't try to analyze it, because the
4219 // resolution chosen here may differ from the resolution chosen in
4220 // other parts of the compiler.
4221 if (SA->getValue().ult(BitWidth)) {
4222 Constant *X =
4223 ConstantInt::get(SA->getContext(),
4224 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
4225 return BinaryOp(Instruction::UDiv, Op->getOperand(0), X);
4226 }
4227 }
4228 return BinaryOp(Op);
4229
4230 case Instruction::ExtractValue: {
4231 auto *EVI = cast<ExtractValueInst>(Op);
4232 if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0)
4233 break;
4234
4235 auto *CI = dyn_cast<CallInst>(EVI->getAggregateOperand());
4236 if (!CI)
4237 break;
4238
4239 if (auto *F = CI->getCalledFunction())
4240 switch (F->getIntrinsicID()) {
4241 case Intrinsic::sadd_with_overflow:
4242 case Intrinsic::uadd_with_overflow:
4243 if (!isOverflowIntrinsicNoWrap(cast<IntrinsicInst>(CI), DT))
4244 return BinaryOp(Instruction::Add, CI->getArgOperand(0),
4245 CI->getArgOperand(1));
4246
4247 // Now that we know that all uses of the arithmetic-result component of
4248 // CI are guarded by the overflow check, we can go ahead and pretend
4249 // that the arithmetic is non-overflowing.
4250 if (F->getIntrinsicID() == Intrinsic::sadd_with_overflow)
4251 return BinaryOp(Instruction::Add, CI->getArgOperand(0),
4252 CI->getArgOperand(1), /* IsNSW = */ true,
4253 /* IsNUW = */ false);
4254 else
4255 return BinaryOp(Instruction::Add, CI->getArgOperand(0),
4256 CI->getArgOperand(1), /* IsNSW = */ false,
4257 /* IsNUW*/ true);
4258 case Intrinsic::ssub_with_overflow:
4259 case Intrinsic::usub_with_overflow:
4260 if (!isOverflowIntrinsicNoWrap(cast<IntrinsicInst>(CI), DT))
4261 return BinaryOp(Instruction::Sub, CI->getArgOperand(0),
4262 CI->getArgOperand(1));
4263
4264 // The same reasoning as sadd/uadd above.
4265 if (F->getIntrinsicID() == Intrinsic::ssub_with_overflow)
4266 return BinaryOp(Instruction::Sub, CI->getArgOperand(0),
4267 CI->getArgOperand(1), /* IsNSW = */ true,
4268 /* IsNUW = */ false);
4269 else
4270 return BinaryOp(Instruction::Sub, CI->getArgOperand(0),
4271 CI->getArgOperand(1), /* IsNSW = */ false,
4272 /* IsNUW = */ true);
4273 case Intrinsic::smul_with_overflow:
4274 case Intrinsic::umul_with_overflow:
4275 return BinaryOp(Instruction::Mul, CI->getArgOperand(0),
4276 CI->getArgOperand(1));
4277 default:
4278 break;
4279 }
4280 }
4281
4282 default:
4283 break;
4284 }
4285
4286 return None;
4287}
4288
4289/// Helper function to createAddRecFromPHIWithCasts. We have a phi
4290/// node whose symbolic (unknown) SCEV is \p SymbolicPHI, which is updated via
4291/// the loop backedge by a SCEVAddExpr, possibly also with a few casts on the
4292/// way. This function checks if \p Op, an operand of this SCEVAddExpr,
4293/// follows one of the following patterns:
4294/// Op == (SExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4295/// Op == (ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4296/// If the SCEV expression of \p Op conforms with one of the expected patterns
4297/// we return the type of the truncation operation, and indicate whether the
4298/// truncated type should be treated as signed/unsigned by setting
4299/// \p Signed to true/false, respectively.
4300static Type *isSimpleCastedPHI(const SCEV *Op, const SCEVUnknown *SymbolicPHI,
4301 bool &Signed, ScalarEvolution &SE) {
4302 // The case where Op == SymbolicPHI (that is, with no type conversions on
4303 // the way) is handled by the regular add recurrence creating logic and
4304 // would have already been triggered in createAddRecForPHI. Reaching it here
4305 // means that createAddRecFromPHI had failed for this PHI before (e.g.,
4306 // because one of the other operands of the SCEVAddExpr updating this PHI is
4307 // not invariant).
4308 //
4309 // Here we look for the case where Op = (ext(trunc(SymbolicPHI))), and in
4310 // this case predicates that allow us to prove that Op == SymbolicPHI will
4311 // be added.
4312 if (Op == SymbolicPHI)
4313 return nullptr;
4314
4315 unsigned SourceBits = SE.getTypeSizeInBits(SymbolicPHI->getType());
4316 unsigned NewBits = SE.getTypeSizeInBits(Op->getType());
4317 if (SourceBits != NewBits)
4318 return nullptr;
4319
4320 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(Op);
4321 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(Op);
4322 if (!SExt && !ZExt)
4323 return nullptr;
4324 const SCEVTruncateExpr *Trunc =
4325 SExt ? dyn_cast<SCEVTruncateExpr>(SExt->getOperand())
4326 : dyn_cast<SCEVTruncateExpr>(ZExt->getOperand());
4327 if (!Trunc)
4328 return nullptr;
4329 const SCEV *X = Trunc->getOperand();
4330 if (X != SymbolicPHI)
4331 return nullptr;
4332 Signed = SExt != nullptr;
4333 return Trunc->getType();
4334}
4335
4336static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) {
4337 if (!PN->getType()->isIntegerTy())
4338 return nullptr;
4339 const Loop *L = LI.getLoopFor(PN->getParent());
4340 if (!L || L->getHeader() != PN->getParent())
4341 return nullptr;
4342 return L;
4343}
4344
4345// Analyze \p SymbolicPHI, a SCEV expression of a phi node, and check if the
4346// computation that updates the phi follows the following pattern:
4347// (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum
4348// which correspond to a phi->trunc->sext/zext->add->phi update chain.
4349// If so, try to see if it can be rewritten as an AddRecExpr under some
4350// Predicates. If successful, return them as a pair. Also cache the results
4351// of the analysis.
4352//
4353// Example usage scenario:
4354// Say the Rewriter is called for the following SCEV:
4355// 8 * ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4356// where:
4357// %X = phi i64 (%Start, %BEValue)
4358// It will visitMul->visitAdd->visitSExt->visitTrunc->visitUnknown(%X),
4359// and call this function with %SymbolicPHI = %X.
4360//
4361// The analysis will find that the value coming around the backedge has
4362// the following SCEV:
4363// BEValue = ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4364// Upon concluding that this matches the desired pattern, the function
4365// will return the pair {NewAddRec, SmallPredsVec} where:
4366// NewAddRec = {%Start,+,%Step}
4367// SmallPredsVec = {P1, P2, P3} as follows:
4368// P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw>
4369// P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64)
4370// P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64)
4371// The returned pair means that SymbolicPHI can be rewritten into NewAddRec
4372// under the predicates {P1,P2,P3}.
4373// This predicated rewrite will be cached in PredicatedSCEVRewrites:
4374// PredicatedSCEVRewrites[{%X,L}] = {NewAddRec, {P1,P2,P3)}
4375//
4376// TODO's:
4377//
4378// 1) Extend the Induction descriptor to also support inductions that involve
4379// casts: When needed (namely, when we are called in the context of the
4380// vectorizer induction analysis), a Set of cast instructions will be
4381// populated by this method, and provided back to isInductionPHI. This is
4382// needed to allow the vectorizer to properly record them to be ignored by
4383// the cost model and to avoid vectorizing them (otherwise these casts,
4384// which are redundant under the runtime overflow checks, will be
4385// vectorized, which can be costly).
4386//
4387// 2) Support additional induction/PHISCEV patterns: We also want to support
4388// inductions where the sext-trunc / zext-trunc operations (partly) occur
4389// after the induction update operation (the induction increment):
4390//
4391// (Trunc iy (SExt/ZExt ix (%SymbolicPHI + InvariantAccum) to iy) to ix)
4392// which correspond to a phi->add->trunc->sext/zext->phi update chain.
4393//
4394// (Trunc iy ((SExt/ZExt ix (%SymbolicPhi) to iy) + InvariantAccum) to ix)
4395// which correspond to a phi->trunc->add->sext/zext->phi update chain.
4396//
4397// 3) Outline common code with createAddRecFromPHI to avoid duplication.
4398Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4399ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI) {
4400 SmallVector<const SCEVPredicate *, 3> Predicates;
4401
4402 // *** Part1: Analyze if we have a phi-with-cast pattern for which we can
4403 // return an AddRec expression under some predicate.
4404
4405 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4406 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4407 assert(L && "Expecting an integer loop header phi")((L && "Expecting an integer loop header phi") ? static_cast
<void> (0) : __assert_fail ("L && \"Expecting an integer loop header phi\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4407, __PRETTY_FUNCTION__))
;
4408
4409 // The loop may have multiple entrances or multiple exits; we can analyze
4410 // this phi as an addrec if it has a unique entry value and a unique
4411 // backedge value.
4412 Value *BEValueV = nullptr, *StartValueV = nullptr;
4413 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4414 Value *V = PN->getIncomingValue(i);
4415 if (L->contains(PN->getIncomingBlock(i))) {
4416 if (!BEValueV) {
4417 BEValueV = V;
4418 } else if (BEValueV != V) {
4419 BEValueV = nullptr;
4420 break;
4421 }
4422 } else if (!StartValueV) {
4423 StartValueV = V;
4424 } else if (StartValueV != V) {
4425 StartValueV = nullptr;
4426 break;
4427 }
4428 }
4429 if (!BEValueV || !StartValueV)
4430 return None;
4431
4432 const SCEV *BEValue = getSCEV(BEValueV);
4433
4434 // If the value coming around the backedge is an add with the symbolic
4435 // value we just inserted, possibly with casts that we can ignore under
4436 // an appropriate runtime guard, then we found a simple induction variable!
4437 const auto *Add = dyn_cast<SCEVAddExpr>(BEValue);
4438 if (!Add)
4439 return None;
4440
4441 // If there is a single occurrence of the symbolic value, possibly
4442 // casted, replace it with a recurrence.
4443 unsigned FoundIndex = Add->getNumOperands();
4444 Type *TruncTy = nullptr;
4445 bool Signed;
4446 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4447 if ((TruncTy =
4448 isSimpleCastedPHI(Add->getOperand(i), SymbolicPHI, Signed, *this)))
4449 if (FoundIndex == e) {
4450 FoundIndex = i;
4451 break;
4452 }
4453
4454 if (FoundIndex == Add->getNumOperands())
4455 return None;
4456
4457 // Create an add with everything but the specified operand.
4458 SmallVector<const SCEV *, 8> Ops;
4459 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4460 if (i != FoundIndex)
4461 Ops.push_back(Add->getOperand(i));
4462 const SCEV *Accum = getAddExpr(Ops);
4463
4464 // The runtime checks will not be valid if the step amount is
4465 // varying inside the loop.
4466 if (!isLoopInvariant(Accum, L))
4467 return None;
4468
4469 // *** Part2: Create the predicates
4470
4471 // Analysis was successful: we have a phi-with-cast pattern for which we
4472 // can return an AddRec expression under the following predicates:
4473 //
4474 // P1: A Wrap predicate that guarantees that Trunc(Start) + i*Trunc(Accum)
4475 // fits within the truncated type (does not overflow) for i = 0 to n-1.
4476 // P2: An Equal predicate that guarantees that
4477 // Start = (Ext ix (Trunc iy (Start) to ix) to iy)
4478 // P3: An Equal predicate that guarantees that
4479 // Accum = (Ext ix (Trunc iy (Accum) to ix) to iy)
4480 //
4481 // As we next prove, the above predicates guarantee that:
4482 // Start + i*Accum = (Ext ix (Trunc iy ( Start + i*Accum ) to ix) to iy)
4483 //
4484 //
4485 // More formally, we want to prove that:
4486 // Expr(i+1) = Start + (i+1) * Accum
4487 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4488 //
4489 // Given that:
4490 // 1) Expr(0) = Start
4491 // 2) Expr(1) = Start + Accum
4492 // = (Ext ix (Trunc iy (Start) to ix) to iy) + Accum :: from P2
4493 // 3) Induction hypothesis (step i):
4494 // Expr(i) = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum
4495 //
4496 // Proof:
4497 // Expr(i+1) =
4498 // = Start + (i+1)*Accum
4499 // = (Start + i*Accum) + Accum
4500 // = Expr(i) + Accum
4501 // = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum + Accum
4502 // :: from step i
4503 //
4504 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) + Accum + Accum
4505 //
4506 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy)
4507 // + (Ext ix (Trunc iy (Accum) to ix) to iy)
4508 // + Accum :: from P3
4509 //
4510 // = (Ext ix (Trunc iy ((Start + (i-1)*Accum) + Accum) to ix) to iy)
4511 // + Accum :: from P1: Ext(x)+Ext(y)=>Ext(x+y)
4512 //
4513 // = (Ext ix (Trunc iy (Start + i*Accum) to ix) to iy) + Accum
4514 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4515 //
4516 // By induction, the same applies to all iterations 1<=i<n:
4517 //
4518
4519 // Create a truncated addrec for which we will add a no overflow check (P1).
4520 const SCEV *StartVal = getSCEV(StartValueV);
4521 const SCEV *PHISCEV =
4522 getAddRecExpr(getTruncateExpr(StartVal, TruncTy),
4523 getTruncateExpr(Accum, TruncTy), L, SCEV::FlagAnyWrap);
4524
4525 // PHISCEV can be either a SCEVConstant or a SCEVAddRecExpr.
4526 // ex: If truncated Accum is 0 and StartVal is a constant, then PHISCEV
4527 // will be constant.
4528 //
4529 // If PHISCEV is a constant, then P1 degenerates into P2 or P3, so we don't
4530 // add P1.
4531 if (const auto *AR = dyn_cast<SCEVAddRecExpr>(PHISCEV)) {
4532 SCEVWrapPredicate::IncrementWrapFlags AddedFlags =
4533 Signed ? SCEVWrapPredicate::IncrementNSSW
4534 : SCEVWrapPredicate::IncrementNUSW;
4535 const SCEVPredicate *AddRecPred = getWrapPredicate(AR, AddedFlags);
4536 Predicates.push_back(AddRecPred);
4537 }
4538
4539 // Create the Equal Predicates P2,P3:
4540
4541 // It is possible that the predicates P2 and/or P3 are computable at
4542 // compile time due to StartVal and/or Accum being constants.
4543 // If either one is, then we can check that now and escape if either P2
4544 // or P3 is false.
4545
4546 // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy)
4547 // for each of StartVal and Accum
4548 auto GetExtendedExpr = [&](const SCEV *Expr) -> const SCEV * {
4549 assert(isLoopInvariant(Expr, L) && "Expr is expected to be invariant")((isLoopInvariant(Expr, L) && "Expr is expected to be invariant"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Expr, L) && \"Expr is expected to be invariant\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4549, __PRETTY_FUNCTION__))
;
4550 const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy);
4551 const SCEV *ExtendedExpr =
4552 Signed ? getSignExtendExpr(TruncatedExpr, Expr->getType())
4553 : getZeroExtendExpr(TruncatedExpr, Expr->getType());
4554 return ExtendedExpr;
4555 };
4556
4557 // Given:
4558 // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy
4559 // = GetExtendedExpr(Expr)
4560 // Determine whether the predicate P: Expr == ExtendedExpr
4561 // is known to be false at compile time
4562 auto PredIsKnownFalse = [&](const SCEV *Expr,
4563 const SCEV *ExtendedExpr) -> bool {
4564 return Expr != ExtendedExpr &&
4565 isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr);
4566 };
4567
4568 const SCEV *StartExtended = GetExtendedExpr(StartVal);
4569 if (PredIsKnownFalse(StartVal, StartExtended)) {
4570 DEBUG(dbgs() << "P2 is compile-time false\n";)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "P2 is compile-time false\n"
;; } } while (false)
;
4571 return None;
4572 }
4573
4574 const SCEV *AccumExtended = GetExtendedExpr(Accum);
4575 if (PredIsKnownFalse(Accum, AccumExtended)) {
4576 DEBUG(dbgs() << "P3 is compile-time false\n";)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "P3 is compile-time false\n"
;; } } while (false)
;
4577 return None;
4578 }
4579
4580 auto AppendPredicate = [&](const SCEV *Expr,
4581 const SCEV *ExtendedExpr) -> void {
4582 if (Expr != ExtendedExpr &&
4583 !isKnownPredicate(ICmpInst::ICMP_EQ, Expr, ExtendedExpr)) {
4584 const SCEVPredicate *Pred = getEqualPredicate(Expr, ExtendedExpr);
4585 DEBUG (dbgs() << "Added Predicate: " << *Pred)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "Added Predicate: " <<
*Pred; } } while (false)
;
4586 Predicates.push_back(Pred);
4587 }
4588 };
4589
4590 AppendPredicate(StartVal, StartExtended);
4591 AppendPredicate(Accum, AccumExtended);
4592
4593 // *** Part3: Predicates are ready. Now go ahead and create the new addrec in
4594 // which the casts had been folded away. The caller can rewrite SymbolicPHI
4595 // into NewAR if it will also add the runtime overflow checks specified in
4596 // Predicates.
4597 auto *NewAR = getAddRecExpr(StartVal, Accum, L, SCEV::FlagAnyWrap);
4598
4599 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> PredRewrite =
4600 std::make_pair(NewAR, Predicates);
4601 // Remember the result of the analysis for this SCEV at this locayyytion.
4602 PredicatedSCEVRewrites[{SymbolicPHI, L}] = PredRewrite;
4603 return PredRewrite;
4604}
4605
4606Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4607ScalarEvolution::createAddRecFromPHIWithCasts(const SCEVUnknown *SymbolicPHI) {
4608 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4609 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4610 if (!L)
4611 return None;
4612
4613 // Check to see if we already analyzed this PHI.
4614 auto I = PredicatedSCEVRewrites.find({SymbolicPHI, L});
4615 if (I != PredicatedSCEVRewrites.end()) {
4616 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> Rewrite =
4617 I->second;
4618 // Analysis was done before and failed to create an AddRec:
4619 if (Rewrite.first == SymbolicPHI)
4620 return None;
4621 // Analysis was done before and succeeded to create an AddRec under
4622 // a predicate:
4623 assert(isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec")((isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec"
) ? static_cast<void> (0) : __assert_fail ("isa<SCEVAddRecExpr>(Rewrite.first) && \"Expected an AddRec\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4623, __PRETTY_FUNCTION__))
;
4624 assert(!(Rewrite.second).empty() && "Expected to find Predicates")((!(Rewrite.second).empty() && "Expected to find Predicates"
) ? static_cast<void> (0) : __assert_fail ("!(Rewrite.second).empty() && \"Expected to find Predicates\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4624, __PRETTY_FUNCTION__))
;
4625 return Rewrite;
4626 }
4627
4628 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4629 Rewrite = createAddRecFromPHIWithCastsImpl(SymbolicPHI);
4630
4631 // Record in the cache that the analysis failed
4632 if (!Rewrite) {
4633 SmallVector<const SCEVPredicate *, 3> Predicates;
4634 PredicatedSCEVRewrites[{SymbolicPHI, L}] = {SymbolicPHI, Predicates};
4635 return None;
4636 }
4637
4638 return Rewrite;
4639}
4640
4641/// A helper function for createAddRecFromPHI to handle simple cases.
4642///
4643/// This function tries to find an AddRec expression for the simplest (yet most
4644/// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)).
4645/// If it fails, createAddRecFromPHI will use a more general, but slow,
4646/// technique for finding the AddRec expression.
4647const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN,
4648 Value *BEValueV,
4649 Value *StartValueV) {
4650 const Loop *L = LI.getLoopFor(PN->getParent());
4651 assert(L && L->getHeader() == PN->getParent())((L && L->getHeader() == PN->getParent()) ? static_cast
<void> (0) : __assert_fail ("L && L->getHeader() == PN->getParent()"
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4651, __PRETTY_FUNCTION__))
;
4652 assert(BEValueV && StartValueV)((BEValueV && StartValueV) ? static_cast<void> (
0) : __assert_fail ("BEValueV && StartValueV", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4652, __PRETTY_FUNCTION__))
;
4653
4654 auto BO = MatchBinaryOp(BEValueV, DT);
4655 if (!BO)
4656 return nullptr;
4657
4658 if (BO->Opcode != Instruction::Add)
4659 return nullptr;
4660
4661 const SCEV *Accum = nullptr;
4662 if (BO->LHS == PN && L->isLoopInvariant(BO->RHS))
4663 Accum = getSCEV(BO->RHS);
4664 else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS))
4665 Accum = getSCEV(BO->LHS);
4666
4667 if (!Accum)
4668 return nullptr;
4669
4670 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4671 if (BO->IsNUW)
4672 Flags = setFlags(Flags, SCEV::FlagNUW);
4673 if (BO->IsNSW)
4674 Flags = setFlags(Flags, SCEV::FlagNSW);
4675
4676 const SCEV *StartVal = getSCEV(StartValueV);
4677 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4678
4679 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
4680
4681 // We can add Flags to the post-inc expression only if we
4682 // know that it is *undefined behavior* for BEValueV to
4683 // overflow.
4684 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
4685 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
4686 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
4687
4688 return PHISCEV;
4689}
4690
4691const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
4692 const Loop *L = LI.getLoopFor(PN->getParent());
4693 if (!L || L->getHeader() != PN->getParent())
4694 return nullptr;
4695
4696 // The loop may have multiple entrances or multiple exits; we can analyze
4697 // this phi as an addrec if it has a unique entry value and a unique
4698 // backedge value.
4699 Value *BEValueV = nullptr, *StartValueV = nullptr;
4700 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4701 Value *V = PN->getIncomingValue(i);
4702 if (L->contains(PN->getIncomingBlock(i))) {
4703 if (!BEValueV) {
4704 BEValueV = V;
4705 } else if (BEValueV != V) {
4706 BEValueV = nullptr;
4707 break;
4708 }
4709 } else if (!StartValueV) {
4710 StartValueV = V;
4711 } else if (StartValueV != V) {
4712 StartValueV = nullptr;
4713 break;
4714 }
4715 }
4716 if (!BEValueV || !StartValueV)
4717 return nullptr;
4718
4719 assert(ValueExprMap.find_as(PN) == ValueExprMap.end() &&((ValueExprMap.find_as(PN) == ValueExprMap.end() && "PHI node already processed?"
) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4720, __PRETTY_FUNCTION__))
4720 "PHI node already processed?")((ValueExprMap.find_as(PN) == ValueExprMap.end() && "PHI node already processed?"
) ? static_cast<void> (0) : __assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4720, __PRETTY_FUNCTION__))
;
4721
4722 // First, try to find AddRec expression without creating a fictituos symbolic
4723 // value for PN.
4724 if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV))
4725 return S;
4726
4727 // Handle PHI node value symbolically.
4728 const SCEV *SymbolicName = getUnknown(PN);
4729 ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName});
4730
4731 // Using this symbolic name for the PHI, analyze the value coming around
4732 // the back-edge.
4733 const SCEV *BEValue = getSCEV(BEValueV);
4734
4735 // NOTE: If BEValue is loop invariant, we know that the PHI node just
4736 // has a special value for the first iteration of the loop.
4737
4738 // If the value coming around the backedge is an add with the symbolic
4739 // value we just inserted, then we found a simple induction variable!
4740 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
4741 // If there is a single occurrence of the symbolic value, replace it
4742 // with a recurrence.
4743 unsigned FoundIndex = Add->getNumOperands();
4744 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4745 if (Add->getOperand(i) == SymbolicName)
4746 if (FoundIndex == e) {
4747 FoundIndex = i;
4748 break;
4749 }
4750
4751 if (FoundIndex != Add->getNumOperands()) {
4752 // Create an add with everything but the specified operand.
4753 SmallVector<const SCEV *, 8> Ops;
4754 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4755 if (i != FoundIndex)
4756 Ops.push_back(Add->getOperand(i));
4757 const SCEV *Accum = getAddExpr(Ops);
4758
4759 bool InvariantF = isLoopInvariant(Accum, L);
4760
4761 if (!InvariantF && Accum->getSCEVType() == scZeroExtend) {
4762 const SCEV *Op = dyn_cast<SCEVZeroExtendExpr>(Accum)->getOperand();
4763 const SCEVUnknown *Un = dyn_cast<SCEVUnknown>(Op);
4764 if (Un && Un->getValue() && isa<Instruction>(Un->getValue()) &&
4765 dyn_cast<Instruction>(Un->getValue())->getOpcode() ==
4766 Instruction::ICmp) {
4767 const SCEV *ICmpSC = evaluateForICmp(cast<ICmpInst>(Un->getValue()));
4768 bool IsConstSC = ICmpSC->getSCEVType() == scConstant;
4769 Accum =
4770 IsConstSC ? getZeroExtendExpr(ICmpSC, Accum->getType()) : Accum;
4771 InvariantF = IsConstSC ? true : false;
4772 }
4773 }
4774
4775 // This is not a valid addrec if the step amount is varying each
4776 // loop iteration, but is not itself an addrec in this loop.
4777 if (InvariantF || (isa<SCEVAddRecExpr>(Accum) &&
4778 cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
4779 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4780
4781 if (auto BO = MatchBinaryOp(BEValueV, DT)) {
4782 if (BO->Opcode == Instruction::Add && BO->LHS == PN) {
4783 if (BO->IsNUW)
4784 Flags = setFlags(Flags, SCEV::FlagNUW);
4785 if (BO->IsNSW)
4786 Flags = setFlags(Flags, SCEV::FlagNSW);
4787 }
4788 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) {
4789 // If the increment is an inbounds GEP, then we know the address
4790 // space cannot be wrapped around. We cannot make any guarantee
4791 // about signed or unsigned overflow because pointers are
4792 // unsigned but we may have a negative index from the base
4793 // pointer. We can guarantee that no unsigned wrap occurs if the
4794 // indices form a positive value.
4795 if (GEP->isInBounds() && GEP->getOperand(0) == PN) {
4796 Flags = setFlags(Flags, SCEV::FlagNW);
4797
4798 const SCEV *Ptr = getSCEV(GEP->getPointerOperand());
4799 if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr)))
4800 Flags = setFlags(Flags, SCEV::FlagNUW);
4801 }
4802
4803 // We cannot transfer nuw and nsw flags from subtraction
4804 // operations -- sub nuw X, Y is not the same as add nuw X, -Y
4805 // for instance.
4806 }
4807
4808 const SCEV *StartVal = getSCEV(StartValueV);
4809 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4810
4811 // Okay, for the entire analysis of this edge we assumed the PHI
4812 // to be symbolic. We now need to go back and purge all of the
4813 // entries for the scalars that use the symbolic expression.
4814 forgetSymbolicName(PN, SymbolicName);
4815 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
4816
4817 // We can add Flags to the post-inc expression only if we
4818 // know that it is *undefined behavior* for BEValueV to
4819 // overflow.
4820 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
4821 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
4822 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
4823
4824 return PHISCEV;
4825 }
4826 }
4827 } else {
4828 // Otherwise, this could be a loop like this:
4829 // i = 0; for (j = 1; ..; ++j) { .... i = j; }
4830 // In this case, j = {1,+,1} and BEValue is j.
4831 // Because the other in-value of i (0) fits the evolution of BEValue
4832 // i really is an addrec evolution.
4833 //
4834 // We can generalize this saying that i is the shifted value of BEValue
4835 // by one iteration:
4836 // PHI(f(0), f({1,+,1})) --> f({0,+,1})
4837 const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this);
4838 const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this);
4839 if (Shifted != getCouldNotCompute() &&
4840 Start != getCouldNotCompute()) {
4841 const SCEV *StartVal = getSCEV(StartValueV);
4842 if (Start == StartVal) {
4843 // Okay, for the entire analysis of this edge we assumed the PHI
4844 // to be symbolic. We now need to go back and purge all of the
4845 // entries for the scalars that use the symbolic expression.
4846 forgetSymbolicName(PN, SymbolicName);
4847 ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted;
4848 return Shifted;
4849 }
4850 }
4851 }
4852
4853 // Remove the temporary PHI node SCEV that has been inserted while intending
4854 // to create an AddRecExpr for this PHI node. We can not keep this temporary
4855 // as it will prevent later (possibly simpler) SCEV expressions to be added
4856 // to the ValueExprMap.
4857 eraseValueFromMap(PN);
4858
4859 return nullptr;
4860}
4861
4862// Checks if the SCEV S is available at BB. S is considered available at BB
4863// if S can be materialized at BB without introducing a fault.
4864static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S,
4865 BasicBlock *BB) {
4866 struct CheckAvailable {
4867 bool TraversalDone = false;
4868 bool Available = true;
4869
4870 const Loop *L = nullptr; // The loop BB is in (can be nullptr)
4871 BasicBlock *BB = nullptr;
4872 DominatorTree &DT;
4873
4874 CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT)
4875 : L(L), BB(BB), DT(DT) {}
4876
4877 bool setUnavailable() {
4878 TraversalDone = true;
4879 Available = false;
4880 return false;
4881 }
4882
4883 bool follow(const SCEV *S) {
4884 switch (S->getSCEVType()) {
4885 case scConstant: case scTruncate: case scZeroExtend: case scSignExtend:
4886 case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr:
4887 // These expressions are available if their operand(s) is/are.
4888 return true;
4889
4890 case scAddRecExpr: {
4891 // We allow add recurrences that are on the loop BB is in, or some
4892 // outer loop. This guarantees availability because the value of the
4893 // add recurrence at BB is simply the "current" value of the induction
4894 // variable. We can relax this in the future; for instance an add
4895 // recurrence on a sibling dominating loop is also available at BB.
4896 const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop();
4897 if (L && (ARLoop == L || ARLoop->contains(L)))
4898 return true;
4899
4900 return setUnavailable();
4901 }
4902
4903 case scUnknown: {
4904 // For SCEVUnknown, we check for simple dominance.
4905 const auto *SU = cast<SCEVUnknown>(S);
4906 Value *V = SU->getValue();
4907
4908 if (isa<Argument>(V))
4909 return false;
4910
4911 if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB))
4912 return false;
4913
4914 return setUnavailable();
4915 }
4916
4917 case scUDivExpr:
4918 case scCouldNotCompute:
4919 // We do not try to smart about these at all.
4920 return setUnavailable();
4921 }
4922 llvm_unreachable("switch should be fully covered!")::llvm::llvm_unreachable_internal("switch should be fully covered!"
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4922)
;
4923 }
4924
4925 bool isDone() { return TraversalDone; }
4926 };
4927
4928 CheckAvailable CA(L, BB, DT);
4929 SCEVTraversal<CheckAvailable> ST(CA);
4930
4931 ST.visitAll(S);
4932 return CA.Available;
4933}
4934
4935// Try to match a control flow sequence that branches out at BI and merges back
4936// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful
4937// match.
4938static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge,
4939 Value *&C, Value *&LHS, Value *&RHS) {
4940 C = BI->getCondition();
4941
4942 BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0));
4943 BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1));
4944
4945 if (!LeftEdge.isSingleEdge())
4946 return false;
4947
4948 assert(RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()")((RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()"
) ? static_cast<void> (0) : __assert_fail ("RightEdge.isSingleEdge() && \"Follows from LeftEdge.isSingleEdge()\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4948, __PRETTY_FUNCTION__))
;
4949
4950 Use &LeftUse = Merge->getOperandUse(0);
4951 Use &RightUse = Merge->getOperandUse(1);
4952
4953 if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) {
4954 LHS = LeftUse;
4955 RHS = RightUse;
4956 return true;
4957 }
4958
4959 if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) {
4960 LHS = RightUse;
4961 RHS = LeftUse;
4962 return true;
4963 }
4964
4965 return false;
4966}
4967
4968const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) {
4969 auto IsReachable =
4970 [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); };
4971 if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) {
4972 const Loop *L = LI.getLoopFor(PN->getParent());
4973
4974 // We don't want to break LCSSA, even in a SCEV expression tree.
4975 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
4976 if (LI.getLoopFor(PN->getIncomingBlock(i)) != L)
4977 return nullptr;
4978
4979 // Try to match
4980 //
4981 // br %cond, label %left, label %right
4982 // left:
4983 // br label %merge
4984 // right:
4985 // br label %merge
4986 // merge:
4987 // V = phi [ %x, %left ], [ %y, %right ]
4988 //
4989 // as "select %cond, %x, %y"
4990
4991 BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock();
4992 assert(IDom && "At least the entry block should dominate PN")((IDom && "At least the entry block should dominate PN"
) ? static_cast<void> (0) : __assert_fail ("IDom && \"At least the entry block should dominate PN\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 4992, __PRETTY_FUNCTION__))
;
4993
4994 auto *BI = dyn_cast<BranchInst>(IDom->getTerminator());
4995 Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr;
4996
4997 if (BI && BI->isConditional() &&
4998 BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) &&
4999 IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) &&
5000 IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent()))
5001 return createNodeForSelectOrPHI(PN, Cond, LHS, RHS);
5002 }
5003
5004 return nullptr;
5005}
5006
5007const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
5008 if (const SCEV *S = createAddRecFromPHI(PN))
5009 return S;
5010
5011 if (const SCEV *S = createNodeFromSelectLikePHI(PN))
5012 return S;
5013
5014 // If the PHI has a single incoming value, follow that value, unless the
5015 // PHI's incoming blocks are in a different loop, in which case doing so
5016 // risks breaking LCSSA form. Instcombine would normally zap these, but
5017 // it doesn't have DominatorTree information, so it may miss cases.
5018 if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC}))
5019 if (LI.replacementPreservesLCSSAForm(PN, V))
5020 return getSCEV(V);
5021
5022 // If it's not a loop phi, we can't handle it yet.
5023 return getUnknown(PN);
5024}
5025
5026const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I,
5027 Value *Cond,
5028 Value *TrueVal,
5029 Value *FalseVal) {
5030 // Handle "constant" branch or select. This can occur for instance when a
5031 // loop pass transforms an inner loop and moves on to process the outer loop.
5032 if (auto *CI = dyn_cast<ConstantInt>(Cond))
5033 return getSCEV(CI->isOne() ? TrueVal : FalseVal);
5034
5035 // Try to match some simple smax or umax patterns.
5036 auto *ICI = dyn_cast<ICmpInst>(Cond);
5037 if (!ICI)
5038 return getUnknown(I);
5039
5040 Value *LHS = ICI->getOperand(0);
5041 Value *RHS = ICI->getOperand(1);
5042
5043 switch (ICI->getPredicate()) {
5044 case ICmpInst::ICMP_SLT:
5045 case ICmpInst::ICMP_SLE:
5046 std::swap(LHS, RHS);
5047 LLVM_FALLTHROUGH[[clang::fallthrough]];
5048 case ICmpInst::ICMP_SGT:
5049 case ICmpInst::ICMP_SGE:
5050 // a >s b ? a+x : b+x -> smax(a, b)+x
5051 // a >s b ? b+x : a+x -> smin(a, b)+x
5052 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5053 const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType());
5054 const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType());
5055 const SCEV *LA = getSCEV(TrueVal);
5056 const SCEV *RA = getSCEV(FalseVal);
5057 const SCEV *LDiff = getMinusSCEV(LA, LS);
5058 const SCEV *RDiff = getMinusSCEV(RA, RS);
5059 if (LDiff == RDiff)
5060 return getAddExpr(getSMaxExpr(LS, RS), LDiff);
5061 LDiff = getMinusSCEV(LA, RS);
5062 RDiff = getMinusSCEV(RA, LS);
5063 if (LDiff == RDiff)
5064 return getAddExpr(getSMinExpr(LS, RS), LDiff);
5065 }
5066 break;
5067 case ICmpInst::ICMP_ULT:
5068 case ICmpInst::ICMP_ULE:
5069 std::swap(LHS, RHS);
5070 LLVM_FALLTHROUGH[[clang::fallthrough]];
5071 case ICmpInst::ICMP_UGT:
5072 case ICmpInst::ICMP_UGE:
5073 // a >u b ? a+x : b+x -> umax(a, b)+x
5074 // a >u b ? b+x : a+x -> umin(a, b)+x
5075 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5076 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5077 const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType());
5078 const SCEV *LA = getSCEV(TrueVal);
5079 const SCEV *RA = getSCEV(FalseVal);
5080 const SCEV *LDiff = getMinusSCEV(LA, LS);
5081 const SCEV *RDiff = getMinusSCEV(RA, RS);
5082 if (LDiff == RDiff)
5083 return getAddExpr(getUMaxExpr(LS, RS), LDiff);
5084 LDiff = getMinusSCEV(LA, RS);
5085 RDiff = getMinusSCEV(RA, LS);
5086 if (LDiff == RDiff)
5087 return getAddExpr(getUMinExpr(LS, RS), LDiff);
5088 }
5089 break;
5090 case ICmpInst::ICMP_NE:
5091 // n != 0 ? n+x : 1+x -> umax(n, 1)+x
5092 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5093 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5094 const SCEV *One = getOne(I->getType());
5095 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5096 const SCEV *LA = getSCEV(TrueVal);
5097 const SCEV *RA = getSCEV(FalseVal);
5098 const SCEV *LDiff = getMinusSCEV(LA, LS);
5099 const SCEV *RDiff = getMinusSCEV(RA, One);
5100 if (LDiff == RDiff)
5101 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5102 }
5103 break;
5104 case ICmpInst::ICMP_EQ:
5105 // n == 0 ? 1+x : n+x -> umax(n, 1)+x
5106 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5107 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5108 const SCEV *One = getOne(I->getType());
5109 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5110 const SCEV *LA = getSCEV(TrueVal);
5111 const SCEV *RA = getSCEV(FalseVal);
5112 const SCEV *LDiff = getMinusSCEV(LA, One);
5113 const SCEV *RDiff = getMinusSCEV(RA, LS);
5114 if (LDiff == RDiff)
5115 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5116 }
5117 break;
5118 default:
5119 break;
5120 }
5121
5122 return getUnknown(I);
5123}
5124
5125/// Expand GEP instructions into add and multiply operations. This allows them
5126/// to be analyzed by regular SCEV code.
5127const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
5128 // Don't attempt to analyze GEPs over unsized objects.
5129 if (!GEP->getSourceElementType()->isSized())
5130 return getUnknown(GEP);
5131
5132 SmallVector<const SCEV *, 4> IndexExprs;
5133 for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index)
5134 IndexExprs.push_back(getSCEV(*Index));
5135 return getGEPExpr(GEP, IndexExprs);
5136}
5137
5138uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) {
5139 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5140 return C->getAPInt().countTrailingZeros();
5141
5142 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
5143 return std::min(GetMinTrailingZeros(T->getOperand()),
5144 (uint32_t)getTypeSizeInBits(T->getType()));
5145
5146 if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
5147 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5148 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5149 ? getTypeSizeInBits(E->getType())
5150 : OpRes;
5151 }
5152
5153 if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
5154 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5155 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5156 ? getTypeSizeInBits(E->getType())
5157 : OpRes;
5158 }
5159
5160 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
5161 // The result is the min of all operands results.
5162 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5163 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5164 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5165 return MinOpRes;
5166 }
5167
5168 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
5169 // The result is the sum of all operands results.
5170 uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
5171 uint32_t BitWidth = getTypeSizeInBits(M->getType());
5172 for (unsigned i = 1, e = M->getNumOperands();
5173 SumOpRes != BitWidth && i != e; ++i)
5174 SumOpRes =
5175 std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth);
5176 return SumOpRes;
5177 }
5178
5179 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
5180 // The result is the min of all operands results.
5181 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5182 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5183 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5184 return MinOpRes;
5185 }
5186
5187 if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
5188 // The result is the min of all operands results.
5189 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5190 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5191 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5192 return MinOpRes;
5193 }
5194
5195 if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
5196 // The result is the min of all operands results.
5197 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5198 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5199 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5200 return MinOpRes;
5201 }
5202
5203 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5204 // For a SCEVUnknown, ask ValueTracking.
5205 KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT);
5206 return Known.countMinTrailingZeros();
5207 }
5208
5209 // SCEVUDivExpr
5210 return 0;
5211}
5212
5213uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
5214 auto I = MinTrailingZerosCache.find(S);
5215 if (I != MinTrailingZerosCache.end())
5216 return I->second;
5217
5218 uint32_t Result = GetMinTrailingZerosImpl(S);
5219 auto InsertPair = MinTrailingZerosCache.insert({S, Result});
5220 assert(InsertPair.second && "Should insert a new key")((InsertPair.second && "Should insert a new key") ? static_cast
<void> (0) : __assert_fail ("InsertPair.second && \"Should insert a new key\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5220, __PRETTY_FUNCTION__))
;
5221 return InsertPair.first->second;
5222}
5223
5224/// Helper method to assign a range to V from metadata present in the IR.
5225static Optional<ConstantRange> GetRangeFromMetadata(Value *V) {
5226 if (Instruction *I = dyn_cast<Instruction>(V))
5227 if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
5228 return getConstantRangeFromMetadata(*MD);
5229
5230 return None;
5231}
5232
5233/// Determine the range for a particular SCEV. If SignHint is
5234/// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges
5235/// with a "cleaner" unsigned (resp. signed) representation.
5236const ConstantRange &
5237ScalarEvolution::getRangeRef(const SCEV *S,
5238 ScalarEvolution::RangeSignHint SignHint) {
5239 DenseMap<const SCEV *, ConstantRange> &Cache =
5240 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges
5241 : SignedRanges;
5242
5243 // See if we've computed this range already.
5244 DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S);
5245 if (I != Cache.end())
5246 return I->second;
5247
5248 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5249 return setRange(C, SignHint, ConstantRange(C->getAPInt()));
5250
5251 unsigned BitWidth = getTypeSizeInBits(S->getType());
5252 ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
5253
5254 // If the value has known zeros, the maximum value will have those known zeros
5255 // as well.
5256 uint32_t TZ = GetMinTrailingZeros(S);
5257 if (TZ != 0) {
5258 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED)
5259 ConservativeResult =
5260 ConstantRange(APInt::getMinValue(BitWidth),
5261 APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1);
5262 else
5263 ConservativeResult = ConstantRange(
5264 APInt::getSignedMinValue(BitWidth),
5265 APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1);
5266 }
5267
5268 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
5269 ConstantRange X = getRangeRef(Add->getOperand(0), SignHint);
5270 for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
5271 X = X.add(getRangeRef(Add->getOperand(i), SignHint));
5272 return setRange(Add, SignHint, ConservativeResult.intersectWith(X));
5273 }
5274
5275 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
5276 ConstantRange X = getRangeRef(Mul->getOperand(0), SignHint);
5277 for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
5278 X = X.multiply(getRangeRef(Mul->getOperand(i), SignHint));
5279 return setRange(Mul, SignHint, ConservativeResult.intersectWith(X));
5280 }
5281
5282 if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
5283 ConstantRange X = getRangeRef(SMax->getOperand(0), SignHint);
5284 for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
5285 X = X.smax(getRangeRef(SMax->getOperand(i), SignHint));
5286 return setRange(SMax, SignHint, ConservativeResult.intersectWith(X));
5287 }
5288
5289 if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
5290 ConstantRange X = getRangeRef(UMax->getOperand(0), SignHint);
5291 for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
5292 X = X.umax(getRangeRef(UMax->getOperand(i), SignHint));
5293 return setRange(UMax, SignHint, ConservativeResult.intersectWith(X));
5294 }
5295
5296 if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
5297 ConstantRange X = getRangeRef(UDiv->getLHS(), SignHint);
5298 ConstantRange Y = getRangeRef(UDiv->getRHS(), SignHint);
5299 return setRange(UDiv, SignHint,
5300 ConservativeResult.intersectWith(X.udiv(Y)));
5301 }
5302
5303 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
5304 ConstantRange X = getRangeRef(ZExt->getOperand(), SignHint);
5305 return setRange(ZExt, SignHint,
5306 ConservativeResult.intersectWith(X.zeroExtend(BitWidth)));
5307 }
5308
5309 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
5310 ConstantRange X = getRangeRef(SExt->getOperand(), SignHint);
5311 return setRange(SExt, SignHint,
5312 ConservativeResult.intersectWith(X.signExtend(BitWidth)));
5313 }
5314
5315 if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
5316 ConstantRange X = getRangeRef(Trunc->getOperand(), SignHint);
5317 return setRange(Trunc, SignHint,
5318 ConservativeResult.intersectWith(X.truncate(BitWidth)));
5319 }
5320
5321 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
5322 // If there's no unsigned wrap, the value will never be less than its
5323 // initial value.
5324 if (AddRec->hasNoUnsignedWrap())
5325 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart()))
5326 if (!C->getValue()->isZero())
5327 ConservativeResult = ConservativeResult.intersectWith(
5328 ConstantRange(C->getAPInt(), APInt(BitWidth, 0)));
5329
5330 // If there's no signed wrap, and all the operands have the same sign or
5331 // zero, the value won't ever change sign.
5332 if (AddRec->hasNoSignedWrap()) {
5333 bool AllNonNeg = true;
5334 bool AllNonPos = true;
5335 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
5336 if (!isKnownNonNegative(AddRec->getOperand(i))) AllNonNeg = false;
5337 if (!isKnownNonPositive(AddRec->getOperand(i))) AllNonPos = false;
5338 }
5339 if (AllNonNeg)
5340 ConservativeResult = ConservativeResult.intersectWith(
5341 ConstantRange(APInt(BitWidth, 0),
5342 APInt::getSignedMinValue(BitWidth)));
5343 else if (AllNonPos)
5344 ConservativeResult = ConservativeResult.intersectWith(
5345 ConstantRange(APInt::getSignedMinValue(BitWidth),
5346 APInt(BitWidth, 1)));
5347 }
5348
5349 // TODO: non-affine addrec
5350 if (AddRec->isAffine()) {
5351 const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
5352 if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
5353 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
5354 auto RangeFromAffine = getRangeForAffineAR(
5355 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
5356 BitWidth);
5357 if (!RangeFromAffine.isFullSet())
5358 ConservativeResult =
5359 ConservativeResult.intersectWith(RangeFromAffine);
5360
5361 auto RangeFromFactoring = getRangeViaFactoring(
5362 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
5363 BitWidth);
5364 if (!RangeFromFactoring.isFullSet())
5365 ConservativeResult =
5366 ConservativeResult.intersectWith(RangeFromFactoring);
5367 }
5368 }
5369
5370 return setRange(AddRec, SignHint, std::move(ConservativeResult));
5371 }
5372
5373 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5374 // Check if the IR explicitly contains !range metadata.
5375 Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue());
5376 if (MDRange.hasValue())
5377 ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue());
5378
5379 // Split here to avoid paying the compile-time cost of calling both
5380 // computeKnownBits and ComputeNumSignBits. This restriction can be lifted
5381 // if needed.
5382 const DataLayout &DL = getDataLayout();
5383 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) {
5384 // For a SCEVUnknown, ask ValueTracking.
5385 KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
5386 if (Known.One != ~Known.Zero + 1)
5387 ConservativeResult =
5388 ConservativeResult.intersectWith(ConstantRange(Known.One,
5389 ~Known.Zero + 1));
5390 } else {
5391 assert(SignHint == ScalarEvolution::HINT_RANGE_SIGNED &&((SignHint == ScalarEvolution::HINT_RANGE_SIGNED && "generalize as needed!"
) ? static_cast<void> (0) : __assert_fail ("SignHint == ScalarEvolution::HINT_RANGE_SIGNED && \"generalize as needed!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5392, __PRETTY_FUNCTION__))
5392 "generalize as needed!")((SignHint == ScalarEvolution::HINT_RANGE_SIGNED && "generalize as needed!"
) ? static_cast<void> (0) : __assert_fail ("SignHint == ScalarEvolution::HINT_RANGE_SIGNED && \"generalize as needed!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5392, __PRETTY_FUNCTION__))
;
5393 unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
5394 if (NS > 1)
5395 ConservativeResult = ConservativeResult.intersectWith(
5396 ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
5397 APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1));
5398 }
5399
5400 return setRange(U, SignHint, std::move(ConservativeResult));
5401 }
5402
5403 return setRange(S, SignHint, std::move(ConservativeResult));
5404}
5405
5406// Given a StartRange, Step and MaxBECount for an expression compute a range of
5407// values that the expression can take. Initially, the expression has a value
5408// from StartRange and then is changed by Step up to MaxBECount times. Signed
5409// argument defines if we treat Step as signed or unsigned.
5410static ConstantRange getRangeForAffineARHelper(APInt Step,
5411 const ConstantRange &StartRange,
5412 const APInt &MaxBECount,
5413 unsigned BitWidth, bool Signed) {
5414 // If either Step or MaxBECount is 0, then the expression won't change, and we
5415 // just need to return the initial range.
5416 if (Step == 0 || MaxBECount == 0)
5417 return StartRange;
5418
5419 // If we don't know anything about the initial value (i.e. StartRange is
5420 // FullRange), then we don't know anything about the final range either.
5421 // Return FullRange.
5422 if (StartRange.isFullSet())
5423 return ConstantRange(BitWidth, /* isFullSet = */ true);
5424
5425 // If Step is signed and negative, then we use its absolute value, but we also
5426 // note that we're moving in the opposite direction.
5427 bool Descending = Signed && Step.isNegative();
5428
5429 if (Signed)
5430 // This is correct even for INT_SMIN. Let's look at i8 to illustrate this:
5431 // abs(INT_SMIN) = abs(-128) = abs(0x80) = -0x80 = 0x80 = 128.
5432 // This equations hold true due to the well-defined wrap-around behavior of
5433 // APInt.
5434 Step = Step.abs();
5435
5436 // Check if Offset is more than full span of BitWidth. If it is, the
5437 // expression is guaranteed to overflow.
5438 if (APInt::getMaxValue(StartRange.getBitWidth()).udiv(Step).ult(MaxBECount))
5439 return ConstantRange(BitWidth, /* isFullSet = */ true);
5440
5441 // Offset is by how much the expression can change. Checks above guarantee no
5442 // overflow here.
5443 APInt Offset = Step * MaxBECount;
5444
5445 // Minimum value of the final range will match the minimal value of StartRange
5446 // if the expression is increasing and will be decreased by Offset otherwise.
5447 // Maximum value of the final range will match the maximal value of StartRange
5448 // if the expression is decreasing and will be increased by Offset otherwise.
5449 APInt StartLower = StartRange.getLower();
5450 APInt StartUpper = StartRange.getUpper() - 1;
5451 APInt MovedBoundary = Descending ? (StartLower - std::move(Offset))
5452 : (StartUpper + std::move(Offset));
5453
5454 // It's possible that the new minimum/maximum value will fall into the initial
5455 // range (due to wrap around). This means that the expression can take any
5456 // value in this bitwidth, and we have to return full range.
5457 if (StartRange.contains(MovedBoundary))
5458 return ConstantRange(BitWidth, /* isFullSet = */ true);
5459
5460 APInt NewLower =
5461 Descending ? std::move(MovedBoundary) : std::move(StartLower);
5462 APInt NewUpper =
5463 Descending ? std::move(StartUpper) : std::move(MovedBoundary);
5464 NewUpper += 1;
5465
5466 // If we end up with full range, return a proper full range.
5467 if (NewLower == NewUpper)
5468 return ConstantRange(BitWidth, /* isFullSet = */ true);
5469
5470 // No overflow detected, return [StartLower, StartUpper + Offset + 1) range.
5471 return ConstantRange(std::move(NewLower), std::move(NewUpper));
5472}
5473
5474ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start,
5475 const SCEV *Step,
5476 const SCEV *MaxBECount,
5477 unsigned BitWidth) {
5478 assert(!isa<SCEVCouldNotCompute>(MaxBECount) &&((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits
(MaxBECount->getType()) <= BitWidth && "Precondition!"
) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5480, __PRETTY_FUNCTION__))
5479 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth &&((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits
(MaxBECount->getType()) <= BitWidth && "Precondition!"
) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5480, __PRETTY_FUNCTION__))
5480 "Precondition!")((!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits
(MaxBECount->getType()) <= BitWidth && "Precondition!"
) ? static_cast<void> (0) : __assert_fail ("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5480, __PRETTY_FUNCTION__))
;
5481
5482 MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType());
5483 APInt MaxBECountValue = getUnsignedRangeMax(MaxBECount);
5484
5485 // First, consider step signed.
5486 ConstantRange StartSRange = getSignedRange(Start);
5487 ConstantRange StepSRange = getSignedRange(Step);
5488
5489 // If Step can be both positive and negative, we need to find ranges for the
5490 // maximum absolute step values in both directions and union them.
5491 ConstantRange SR =
5492 getRangeForAffineARHelper(StepSRange.getSignedMin(), StartSRange,
5493 MaxBECountValue, BitWidth, /* Signed = */ true);
5494 SR = SR.unionWith(getRangeForAffineARHelper(StepSRange.getSignedMax(),
5495 StartSRange, MaxBECountValue,
5496 BitWidth, /* Signed = */ true));
5497
5498 // Next, consider step unsigned.
5499 ConstantRange UR = getRangeForAffineARHelper(
5500 getUnsignedRangeMax(Step), getUnsignedRange(Start),
5501 MaxBECountValue, BitWidth, /* Signed = */ false);
5502
5503 // Finally, intersect signed and unsigned ranges.
5504 return SR.intersectWith(UR);
5505}
5506
5507ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
5508 const SCEV *Step,
5509 const SCEV *MaxBECount,
5510 unsigned BitWidth) {
5511 // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q})
5512 // == RangeOf({A,+,P}) union RangeOf({B,+,Q})
5513
5514 struct SelectPattern {
5515 Value *Condition = nullptr;
5516 APInt TrueValue;
5517 APInt FalseValue;
5518
5519 explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth,
5520 const SCEV *S) {
5521 Optional<unsigned> CastOp;
5522 APInt Offset(BitWidth, 0);
5523
5524 assert(SE.getTypeSizeInBits(S->getType()) == BitWidth &&((SE.getTypeSizeInBits(S->getType()) == BitWidth &&
"Should be!") ? static_cast<void> (0) : __assert_fail (
"SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5525, __PRETTY_FUNCTION__))
5525 "Should be!")((SE.getTypeSizeInBits(S->getType()) == BitWidth &&
"Should be!") ? static_cast<void> (0) : __assert_fail (
"SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5525, __PRETTY_FUNCTION__))
;
5526
5527 // Peel off a constant offset:
5528 if (auto *SA = dyn_cast<SCEVAddExpr>(S)) {
5529 // In the future we could consider being smarter here and handle
5530 // {Start+Step,+,Step} too.
5531 if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
5532 return;
5533
5534 Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
5535 S = SA->getOperand(1);
5536 }
5537
5538 // Peel off a cast operation
5539 if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) {
5540 CastOp = SCast->getSCEVType();
5541 S = SCast->getOperand();
5542 }
5543
5544 using namespace llvm::PatternMatch;
5545
5546 auto *SU = dyn_cast<SCEVUnknown>(S);
5547 const APInt *TrueVal, *FalseVal;
5548 if (!SU ||
5549 !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal),
5550 m_APInt(FalseVal)))) {
5551 Condition = nullptr;
5552 return;
5553 }
5554
5555 TrueValue = *TrueVal;
5556 FalseValue = *FalseVal;
5557
5558 // Re-apply the cast we peeled off earlier
5559 if (CastOp.hasValue())
5560 switch (*CastOp) {
5561 default:
5562 llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5562)
;
5563
5564 case scTruncate:
5565 TrueValue = TrueValue.trunc(BitWidth);
5566 FalseValue = FalseValue.trunc(BitWidth);
5567 break;
5568 case scZeroExtend:
5569 TrueValue = TrueValue.zext(BitWidth);
5570 FalseValue = FalseValue.zext(BitWidth);
5571 break;
5572 case scSignExtend:
5573 TrueValue = TrueValue.sext(BitWidth);
5574 FalseValue = FalseValue.sext(BitWidth);
5575 break;
5576 }
5577
5578 // Re-apply the constant offset we peeled off earlier
5579 TrueValue += Offset;
5580 FalseValue += Offset;
5581 }
5582
5583 bool isRecognized() { return Condition != nullptr; }
5584 };
5585
5586 SelectPattern StartPattern(*this, BitWidth, Start);
5587 if (!StartPattern.isRecognized())
5588 return ConstantRange(BitWidth, /* isFullSet = */ true);
5589
5590 SelectPattern StepPattern(*this, BitWidth, Step);
5591 if (!StepPattern.isRecognized())
5592 return ConstantRange(BitWidth, /* isFullSet = */ true);
5593
5594 if (StartPattern.Condition != StepPattern.Condition) {
5595 // We don't handle this case today; but we could, by considering four
5596 // possibilities below instead of two. I'm not sure if there are cases where
5597 // that will help over what getRange already does, though.
5598 return ConstantRange(BitWidth, /* isFullSet = */ true);
5599 }
5600
5601 // NB! Calling ScalarEvolution::getConstant is fine, but we should not try to
5602 // construct arbitrary general SCEV expressions here. This function is called
5603 // from deep in the call stack, and calling getSCEV (on a sext instruction,
5604 // say) can end up caching a suboptimal value.
5605
5606 // FIXME: without the explicit `this` receiver below, MSVC errors out with
5607 // C2352 and C2512 (otherwise it isn't needed).
5608
5609 const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue);
5610 const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue);
5611 const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue);
5612 const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue);
5613
5614 ConstantRange TrueRange =
5615 this->getRangeForAffineAR(TrueStart, TrueStep, MaxBECount, BitWidth);
5616 ConstantRange FalseRange =
5617 this->getRangeForAffineAR(FalseStart, FalseStep, MaxBECount, BitWidth);
5618
5619 return TrueRange.unionWith(FalseRange);
5620}
5621
5622SCEV::NoWrapFlags ScalarEvolution::getNoWrapFlagsFromUB(const Value *V) {
5623 if (isa<ConstantExpr>(V)) return SCEV::FlagAnyWrap;
5624 const BinaryOperator *BinOp = cast<BinaryOperator>(V);
5625
5626 // Return early if there are no flags to propagate to the SCEV.
5627 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5628 if (BinOp->hasNoUnsignedWrap())
5629 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
5630 if (BinOp->hasNoSignedWrap())
5631 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
5632 if (Flags == SCEV::FlagAnyWrap)
5633 return SCEV::FlagAnyWrap;
5634
5635 return isSCEVExprNeverPoison(BinOp) ? Flags : SCEV::FlagAnyWrap;
5636}
5637
5638bool ScalarEvolution::isSCEVExprNeverPoison(const Instruction *I) {
5639 // Here we check that I is in the header of the innermost loop containing I,
5640 // since we only deal with instructions in the loop header. The actual loop we
5641 // need to check later will come from an add recurrence, but getting that
5642 // requires computing the SCEV of the operands, which can be expensive. This
5643 // check we can do cheaply to rule out some cases early.
5644 Loop *InnermostContainingLoop = LI.getLoopFor(I->getParent());
5645 if (InnermostContainingLoop == nullptr ||
5646 InnermostContainingLoop->getHeader() != I->getParent())
5647 return false;
5648
5649 // Only proceed if we can prove that I does not yield poison.
5650 if (!programUndefinedIfFullPoison(I))
5651 return false;
5652
5653 // At this point we know that if I is executed, then it does not wrap
5654 // according to at least one of NSW or NUW. If I is not executed, then we do
5655 // not know if the calculation that I represents would wrap. Multiple
5656 // instructions can map to the same SCEV. If we apply NSW or NUW from I to
5657 // the SCEV, we must guarantee no wrapping for that SCEV also when it is
5658 // derived from other instructions that map to the same SCEV. We cannot make
5659 // that guarantee for cases where I is not executed. So we need to find the
5660 // loop that I is considered in relation to and prove that I is executed for
5661 // every iteration of that loop. That implies that the value that I
5662 // calculates does not wrap anywhere in the loop, so then we can apply the
5663 // flags to the SCEV.
5664 //
5665 // We check isLoopInvariant to disambiguate in case we are adding recurrences
5666 // from different loops, so that we know which loop to prove that I is
5667 // executed in.
5668 for (unsigned OpIndex = 0; OpIndex < I->getNumOperands(); ++OpIndex) {
5669 // I could be an extractvalue from a call to an overflow intrinsic.
5670 // TODO: We can do better here in some cases.
5671 if (!isSCEVable(I->getOperand(OpIndex)->getType()))
5672 return false;
5673 const SCEV *Op = getSCEV(I->getOperand(OpIndex));
5674 if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
5675 bool AllOtherOpsLoopInvariant = true;
5676 for (unsigned OtherOpIndex = 0; OtherOpIndex < I->getNumOperands();
5677 ++OtherOpIndex) {
5678 if (OtherOpIndex != OpIndex) {
5679 const SCEV *OtherOp = getSCEV(I->getOperand(OtherOpIndex));
5680 if (!isLoopInvariant(OtherOp, AddRec->getLoop())) {
5681 AllOtherOpsLoopInvariant = false;
5682 break;
5683 }
5684 }
5685 }
5686 if (AllOtherOpsLoopInvariant &&
5687 isGuaranteedToExecuteForEveryIteration(I, AddRec->getLoop()))
5688 return true;
5689 }
5690 }
5691 return false;
5692}
5693
5694bool ScalarEvolution::isAddRecNeverPoison(const Instruction *I, const Loop *L) {
5695 // If we know that \c I can never be poison period, then that's enough.
5696 if (isSCEVExprNeverPoison(I))
5697 return true;
5698
5699 // For an add recurrence specifically, we assume that infinite loops without
5700 // side effects are undefined behavior, and then reason as follows:
5701 //
5702 // If the add recurrence is poison in any iteration, it is poison on all
5703 // future iterations (since incrementing poison yields poison). If the result
5704 // of the add recurrence is fed into the loop latch condition and the loop
5705 // does not contain any throws or exiting blocks other than the latch, we now
5706 // have the ability to "choose" whether the backedge is taken or not (by
5707 // choosing a sufficiently evil value for the poison feeding into the branch)
5708 // for every iteration including and after the one in which \p I first became
5709 // poison. There are two possibilities (let's call the iteration in which \p
5710 // I first became poison as K):
5711 //
5712 // 1. In the set of iterations including and after K, the loop body executes
5713 // no side effects. In this case executing the backege an infinte number
5714 // of times will yield undefined behavior.
5715 //
5716 // 2. In the set of iterations including and after K, the loop body executes
5717 // at least one side effect. In this case, that specific instance of side
5718 // effect is control dependent on poison, which also yields undefined
5719 // behavior.
5720
5721 auto *ExitingBB = L->getExitingBlock();
5722 auto *LatchBB = L->getLoopLatch();
5723 if (!ExitingBB || !LatchBB || ExitingBB != LatchBB)
5724 return false;
5725
5726 SmallPtrSet<const Instruction *, 16> Pushed;
5727 SmallVector<const Instruction *, 8> PoisonStack;
5728
5729 // We start by assuming \c I, the post-inc add recurrence, is poison. Only
5730 // things that are known to be fully poison under that assumption go on the
5731 // PoisonStack.
5732 Pushed.insert(I);
5733 PoisonStack.push_back(I);
5734
5735 bool LatchControlDependentOnPoison = false;
5736 while (!PoisonStack.empty() && !LatchControlDependentOnPoison) {
5737 const Instruction *Poison = PoisonStack.pop_back_val();
5738
5739 for (auto *PoisonUser : Poison->users()) {
5740 if (propagatesFullPoison(cast<Instruction>(PoisonUser))) {
5741 if (Pushed.insert(cast<Instruction>(PoisonUser)).second)
5742 PoisonStack.push_back(cast<Instruction>(PoisonUser));
5743 } else if (auto *BI = dyn_cast<BranchInst>(PoisonUser)) {
5744 assert(BI->isConditional() && "Only possibility!")((BI->isConditional() && "Only possibility!") ? static_cast
<void> (0) : __assert_fail ("BI->isConditional() && \"Only possibility!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5744, __PRETTY_FUNCTION__))
;
5745 if (BI->getParent() == LatchBB) {
5746 LatchControlDependentOnPoison = true;
5747 break;
5748 }
5749 }
5750 }
5751 }
5752
5753 return LatchControlDependentOnPoison && loopHasNoAbnormalExits(L);
5754}
5755
5756ScalarEvolution::LoopProperties
5757ScalarEvolution::getLoopProperties(const Loop *L) {
5758 using LoopProperties = ScalarEvolution::LoopProperties;
5759
5760 auto Itr = LoopPropertiesCache.find(L);
5761 if (Itr == LoopPropertiesCache.end()) {
5762 auto HasSideEffects = [](Instruction *I) {
5763 if (auto *SI = dyn_cast<StoreInst>(I))
5764 return !SI->isSimple();
5765
5766 return I->mayHaveSideEffects();
5767 };
5768
5769 LoopProperties LP = {/* HasNoAbnormalExits */ true,
5770 /*HasNoSideEffects*/ true};
5771
5772 for (auto *BB : L->getBlocks())
5773 for (auto &I : *BB) {
5774 if (!isGuaranteedToTransferExecutionToSuccessor(&I))
5775 LP.HasNoAbnormalExits = false;
5776 if (HasSideEffects(&I))
5777 LP.HasNoSideEffects = false;
5778 if (!LP.HasNoAbnormalExits && !LP.HasNoSideEffects)
5779 break; // We're already as pessimistic as we can get.
5780 }
5781
5782 auto InsertPair = LoopPropertiesCache.insert({L, LP});
5783 assert(InsertPair.second && "We just checked!")((InsertPair.second && "We just checked!") ? static_cast
<void> (0) : __assert_fail ("InsertPair.second && \"We just checked!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 5783, __PRETTY_FUNCTION__))
;
5784 Itr = InsertPair.first;
5785 }
5786
5787 return Itr->second;
5788}
5789
5790const SCEV *ScalarEvolution::createSCEV(Value *V) {
5791 if (!isSCEVable(V->getType()))
5792 return getUnknown(V);
5793
5794 if (Instruction *I = dyn_cast<Instruction>(V)) {
5795 // Don't attempt to analyze instructions in blocks that aren't
5796 // reachable. Such instructions don't matter, and they aren't required
5797 // to obey basic rules for definitions dominating uses which this
5798 // analysis depends on.
5799 if (!DT.isReachableFromEntry(I->getParent()))
5800 return getUnknown(V);
5801 } else if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
5802 return getConstant(CI);
5803 else if (isa<ConstantPointerNull>(V))
5804 return getZero(V->getType());
5805 else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
5806 return GA->isInterposable() ? getUnknown(V) : getSCEV(GA->getAliasee());
5807 else if (!isa<ConstantExpr>(V))
5808 return getUnknown(V);
5809
5810 Operator *U = cast<Operator>(V);
5811 if (auto BO = MatchBinaryOp(U, DT)) {
5812 switch (BO->Opcode) {
5813 case Instruction::Add: {
5814 // The simple thing to do would be to just call getSCEV on both operands
5815 // and call getAddExpr with the result. However if we're looking at a
5816 // bunch of things all added together, this can be quite inefficient,
5817 // because it leads to N-1 getAddExpr calls for N ultimate operands.
5818 // Instead, gather up all the operands and make a single getAddExpr call.
5819 // LLVM IR canonical form means we need only traverse the left operands.
5820 SmallVector<const SCEV *, 4> AddOps;
5821 do {
5822 if (BO->Op) {
5823 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
5824 AddOps.push_back(OpSCEV);
5825 break;
5826 }
5827
5828 // If a NUW or NSW flag can be applied to the SCEV for this
5829 // addition, then compute the SCEV for this addition by itself
5830 // with a separate call to getAddExpr. We need to do that
5831 // instead of pushing the operands of the addition onto AddOps,
5832 // since the flags are only known to apply to this particular
5833 // addition - they may not apply to other additions that can be
5834 // formed with operands from AddOps.
5835 const SCEV *RHS = getSCEV(BO->RHS);
5836 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
5837 if (Flags != SCEV::FlagAnyWrap) {
5838 const SCEV *LHS = getSCEV(BO->LHS);
5839 if (BO->Opcode == Instruction::Sub)
5840 AddOps.push_back(getMinusSCEV(LHS, RHS, Flags));
5841 else
5842 AddOps.push_back(getAddExpr(LHS, RHS, Flags));
5843 break;
5844 }
5845 }
5846
5847 if (BO->Opcode == Instruction::Sub)
5848 AddOps.push_back(getNegativeSCEV(getSCEV(BO->RHS)));
5849 else
5850 AddOps.push_back(getSCEV(BO->RHS));
5851
5852 auto NewBO = MatchBinaryOp(BO->LHS, DT);
5853 if (!NewBO || (NewBO->Opcode != Instruction::Add &&
5854 NewBO->Opcode != Instruction::Sub)) {
5855 AddOps.push_back(getSCEV(BO->LHS));
5856 break;
5857 }
5858 BO = NewBO;
5859 } while (true);
5860
5861 return getAddExpr(AddOps);
5862 }
5863
5864 case Instruction::Mul: {
5865 SmallVector<const SCEV *, 4> MulOps;
5866 do {
5867 if (BO->Op) {
5868 if (auto *OpSCEV = getExistingSCEV(BO->Op)) {
5869 MulOps.push_back(OpSCEV);
5870 break;
5871 }
5872
5873 SCEV::NoWrapFlags Flags = getNoWrapFlagsFromUB(BO->Op);
5874 if (Flags != SCEV::FlagAnyWrap) {
5875 MulOps.push_back(
5876 getMulExpr(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags));
5877 break;
5878 }
5879 }
5880
5881 MulOps.push_back(getSCEV(BO->RHS));
5882 auto NewBO = MatchBinaryOp(BO->LHS, DT);
5883 if (!NewBO || NewBO->Opcode != Instruction::Mul) {
5884 MulOps.push_back(getSCEV(BO->LHS));
5885 break;
5886 }
5887 BO = NewBO;
5888 } while (true);
5889
5890 return getMulExpr(MulOps);
5891 }
5892 case Instruction::UDiv:
5893 return getUDivExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
5894 case Instruction::URem:
5895 return getURemExpr(getSCEV(BO->LHS), getSCEV(BO->RHS));
5896 case Instruction::Sub: {
5897 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
5898 if (BO->Op)
5899 Flags = getNoWrapFlagsFromUB(BO->Op);
5900 return getMinusSCEV(getSCEV(BO->LHS), getSCEV(BO->RHS), Flags);
5901 }
5902 case Instruction::And:
5903 // For an expression like x&255 that merely masks off the high bits,
5904 // use zext(trunc(x)) as the SCEV expression.
5905 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
5906 if (CI->isZero())
5907 return getSCEV(BO->RHS);
5908 if (CI->isMinusOne())
5909 return getSCEV(BO->LHS);
5910 const APInt &A = CI->getValue();
5911
5912 // Instcombine's ShrinkDemandedConstant may strip bits out of
5913 // constants, obscuring what would otherwise be a low-bits mask.
5914 // Use computeKnownBits to compute what ShrinkDemandedConstant
5915 // knew about to reconstruct a low-bits mask value.
5916 unsigned LZ = A.countLeadingZeros();
5917 unsigned TZ = A.countTrailingZeros();
5918 unsigned BitWidth = A.getBitWidth();
5919 KnownBits Known(BitWidth);
5920 computeKnownBits(BO->LHS, Known, getDataLayout(),
5921 0, &AC, nullptr, &DT);
5922
5923 APInt EffectiveMask =
5924 APInt::getLowBitsSet(BitWidth, BitWidth - LZ - TZ).shl(TZ);
5925 if ((LZ != 0 || TZ != 0) && !((~A & ~Known.Zero) & EffectiveMask)) {
5926 const SCEV *MulCount = getConstant(APInt::getOneBitSet(BitWidth, TZ));
5927 const SCEV *LHS = getSCEV(BO->LHS);
5928 const SCEV *ShiftedLHS = nullptr;
5929 if (auto *LHSMul = dyn_cast<SCEVMulExpr>(LHS)) {
5930 if (auto *OpC = dyn_cast<SCEVConstant>(LHSMul->getOperand(0))) {
5931 // For an expression like (x * 8) & 8, simplify the multiply.
5932 unsigned MulZeros = OpC->getAPInt().countTrailingZeros();
5933 unsigned GCD = std::min(MulZeros, TZ);
5934 APInt DivAmt = APInt::getOneBitSet(BitWidth, TZ - GCD);
5935 SmallVector<const SCEV*, 4> MulOps;
5936 MulOps.push_back(getConstant(OpC->getAPInt().lshr(GCD)));
5937 MulOps.append(LHSMul->op_begin() + 1, LHSMul->op_end());
5938 auto *NewMul = getMulExpr(MulOps, LHSMul->getNoWrapFlags());
5939 ShiftedLHS = getUDivExpr(NewMul, getConstant(DivAmt));
5940 }
5941 }
5942 if (!ShiftedLHS)
5943 ShiftedLHS = getUDivExpr(LHS, MulCount);
5944 return getMulExpr(
5945 getZeroExtendExpr(
5946 getTruncateExpr(ShiftedLHS,
5947 IntegerType::get(getContext(), BitWidth - LZ - TZ)),
5948 BO->LHS->getType()),
5949 MulCount);
5950 }
5951 }
5952 break;
5953
5954 case Instruction::Or:
5955 // If the RHS of the Or is a constant, we may have something like:
5956 // X*4+1 which got turned into X*4|1. Handle this as an Add so loop
5957 // optimizations will transparently handle this case.
5958 //
5959 // In order for this transformation to be safe, the LHS must be of the
5960 // form X*(2^n) and the Or constant must be less than 2^n.
5961 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
5962 const SCEV *LHS = getSCEV(BO->LHS);
5963 const APInt &CIVal = CI->getValue();
5964 if (GetMinTrailingZeros(LHS) >=
5965 (CIVal.getBitWidth() - CIVal.countLeadingZeros())) {
5966 // Build a plain add SCEV.
5967 const SCEV *S = getAddExpr(LHS, getSCEV(CI));
5968 // If the LHS of the add was an addrec and it has no-wrap flags,
5969 // transfer the no-wrap flags, since an or won't introduce a wrap.
5970 if (const SCEVAddRecExpr *NewAR = dyn_cast<SCEVAddRecExpr>(S)) {
5971 const SCEVAddRecExpr *OldAR = cast<SCEVAddRecExpr>(LHS);
5972 const_cast<SCEVAddRecExpr *>(NewAR)->setNoWrapFlags(
5973 OldAR->getNoWrapFlags());
5974 }
5975 return S;
5976 }
5977 }
5978 break;
5979
5980 case Instruction::Xor:
5981 if (ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS)) {
5982 // If the RHS of xor is -1, then this is a not operation.
5983 if (CI->isMinusOne())
5984 return getNotSCEV(getSCEV(BO->LHS));
5985
5986 // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask.
5987 // This is a variant of the check for xor with -1, and it handles
5988 // the case where instcombine has trimmed non-demanded bits out
5989 // of an xor with -1.
5990 if (auto *LBO = dyn_cast<BinaryOperator>(BO->LHS))
5991 if (ConstantInt *LCI = dyn_cast<ConstantInt>(LBO->getOperand(1)))
5992 if (LBO->getOpcode() == Instruction::And &&
5993 LCI->getValue() == CI->getValue())
5994 if (const SCEVZeroExtendExpr *Z =
5995 dyn_cast<SCEVZeroExtendExpr>(getSCEV(BO->LHS))) {
5996 Type *UTy = BO->LHS->getType();
5997 const SCEV *Z0 = Z->getOperand();
5998 Type *Z0Ty = Z0->getType();
5999 unsigned Z0TySize = getTypeSizeInBits(Z0Ty);
6000
6001 // If C is a low-bits mask, the zero extend is serving to
6002 // mask off the high bits. Complement the operand and
6003 // re-apply the zext.
6004 if (CI->getValue().isMask(Z0TySize))
6005 return getZeroExtendExpr(getNotSCEV(Z0), UTy);
6006
6007 // If C is a single bit, it may be in the sign-bit position
6008 // before the zero-extend. In this case, represent the xor
6009 // using an add, which is equivalent, and re-apply the zext.
6010 APInt Trunc = CI->getValue().trunc(Z0TySize);
6011 if (Trunc.zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
6012 Trunc.isSignMask())
6013 return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
6014 UTy);
6015 }
6016 }
6017 break;
6018
6019 case Instruction::Shl:
6020 // Turn shift left of a constant amount into a multiply.
6021 if (ConstantInt *SA = dyn_cast<ConstantInt>(BO->RHS)) {
6022 uint32_t BitWidth = cast<IntegerType>(SA->getType())->getBitWidth();
6023
6024 // If the shift count is not less than the bitwidth, the result of
6025 // the shift is undefined. Don't try to analyze it, because the
6026 // resolution chosen here may differ from the resolution chosen in
6027 // other parts of the compiler.
6028 if (SA->getValue().uge(BitWidth))
6029 break;
6030
6031 // It is currently not resolved how to interpret NSW for left
6032 // shift by BitWidth - 1, so we avoid applying flags in that
6033 // case. Remove this check (or this comment) once the situation
6034 // is resolved. See
6035 // http://lists.llvm.org/pipermail/llvm-dev/2015-April/084195.html
6036 // and http://reviews.llvm.org/D8890 .
6037 auto Flags = SCEV::FlagAnyWrap;
6038 if (BO->Op && SA->getValue().ult(BitWidth - 1))
6039 Flags = getNoWrapFlagsFromUB(BO->Op);
6040
6041 Constant *X = ConstantInt::get(getContext(),
6042 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
6043 return getMulExpr(getSCEV(BO->LHS), getSCEV(X), Flags);
6044 }
6045 break;
6046
6047 case Instruction::AShr: {
6048 // AShr X, C, where C is a constant.
6049 ConstantInt *CI = dyn_cast<ConstantInt>(BO->RHS);
6050 if (!CI)
6051 break;
6052
6053 Type *OuterTy = BO->LHS->getType();
6054 uint64_t BitWidth = getTypeSizeInBits(OuterTy);
6055 // If the shift count is not less than the bitwidth, the result of
6056 // the shift is undefined. Don't try to analyze it, because the
6057 // resolution chosen here may differ from the resolution chosen in
6058 // other parts of the compiler.
6059 if (CI->getValue().uge(BitWidth))
6060 break;
6061
6062 if (CI->isZero())
6063 return getSCEV(BO->LHS); // shift by zero --> noop
6064
6065 uint64_t AShrAmt = CI->getZExtValue();
6066 Type *TruncTy = IntegerType::get(getContext(), BitWidth - AShrAmt);
6067
6068 Operator *L = dyn_cast<Operator>(BO->LHS);
6069 if (L && L->getOpcode() == Instruction::Shl) {
6070 // X = Shl A, n
6071 // Y = AShr X, m
6072 // Both n and m are constant.
6073
6074 const SCEV *ShlOp0SCEV = getSCEV(L->getOperand(0));
6075 if (L->getOperand(1) == BO->RHS)
6076 // For a two-shift sext-inreg, i.e. n = m,
6077 // use sext(trunc(x)) as the SCEV expression.
6078 return getSignExtendExpr(
6079 getTruncateExpr(ShlOp0SCEV, TruncTy), OuterTy);
6080
6081 ConstantInt *ShlAmtCI = dyn_cast<ConstantInt>(L->getOperand(1));
6082 if (ShlAmtCI && ShlAmtCI->getValue().ult(BitWidth)) {
6083 uint64_t ShlAmt = ShlAmtCI->getZExtValue();
6084 if (ShlAmt > AShrAmt) {
6085 // When n > m, use sext(mul(trunc(x), 2^(n-m)))) as the SCEV
6086 // expression. We already checked that ShlAmt < BitWidth, so
6087 // the multiplier, 1 << (ShlAmt - AShrAmt), fits into TruncTy as
6088 // ShlAmt - AShrAmt < Amt.
6089 APInt Mul = APInt::getOneBitSet(BitWidth - AShrAmt,
6090 ShlAmt - AShrAmt);
6091 return getSignExtendExpr(
6092 getMulExpr(getTruncateExpr(ShlOp0SCEV, TruncTy),
6093 getConstant(Mul)), OuterTy);
6094 }
6095 }
6096 }
6097 break;
6098 }
6099 }
6100 }
6101
6102 switch (U->getOpcode()) {
6103 case Instruction::Trunc:
6104 return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());
6105
6106 case Instruction::ZExt:
6107 return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType());
6108
6109 case Instruction::SExt:
6110 if (auto BO = MatchBinaryOp(U->getOperand(0), DT)) {
6111 // The NSW flag of a subtract does not always survive the conversion to
6112 // A + (-1)*B. By pushing sign extension onto its operands we are much
6113 // more likely to preserve NSW and allow later AddRec optimisations.
6114 //
6115 // NOTE: This is effectively duplicating this logic from getSignExtend:
6116 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
6117 // but by that point the NSW information has potentially been lost.
6118 if (BO->Opcode == Instruction::Sub && BO->IsNSW) {
6119 Type *Ty = U->getType();
6120 auto *V1 = getSignExtendExpr(getSCEV(BO->LHS), Ty);
6121 auto *V2 = getSignExtendExpr(getSCEV(BO->RHS), Ty);
6122 return getMinusSCEV(V1, V2, SCEV::FlagNSW);
6123 }
6124 }
6125 return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType());
6126
6127 case Instruction::BitCast:
6128 // BitCasts are no-op casts so we just eliminate the cast.
6129 if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType()))
6130 return getSCEV(U->getOperand(0));
6131 break;
6132
6133 // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can
6134 // lead to pointer expressions which cannot safely be expanded to GEPs,
6135 // because ScalarEvolution doesn't respect the GEP aliasing rules when
6136 // simplifying integer expressions.
6137
6138 case Instruction::GetElementPtr:
6139 return createNodeForGEP(cast<GEPOperator>(U));
6140
6141 case Instruction::PHI:
6142 return createNodeForPHI(cast<PHINode>(U));
6143
6144 case Instruction::Select:
6145 // U can also be a select constant expr, which let fall through. Since
6146 // createNodeForSelect only works for a condition that is an `ICmpInst`, and
6147 // constant expressions cannot have instructions as operands, we'd have
6148 // returned getUnknown for a select constant expressions anyway.
6149 if (isa<Instruction>(U))
6150 return createNodeForSelectOrPHI(cast<Instruction>(U), U->getOperand(0),
6151 U->getOperand(1), U->getOperand(2));
6152 break;
6153
6154 case Instruction::Call:
6155 case Instruction::Invoke:
6156 if (Value *RV = CallSite(U).getReturnedArgOperand())
6157 return getSCEV(RV);
6158 break;
6159 }
6160
6161 return getUnknown(V);
6162}
6163
6164//===----------------------------------------------------------------------===//
6165// Iteration Count Computation Code
6166//
6167
6168static unsigned getConstantTripCount(const SCEVConstant *ExitCount) {
6169 if (!ExitCount)
6170 return 0;
6171
6172 ConstantInt *ExitConst = ExitCount->getValue();
6173
6174 // Guard against huge trip counts.
6175 if (ExitConst->getValue().getActiveBits() > 32)
6176 return 0;
6177
6178 // In case of integer overflow, this returns 0, which is correct.
6179 return ((unsigned)ExitConst->getZExtValue()) + 1;
6180}
6181
6182unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L) {
6183 if (BasicBlock *ExitingBB = L->getExitingBlock())
6184 return getSmallConstantTripCount(L, ExitingBB);
6185
6186 // No trip count information for multiple exits.
6187 return 0;
6188}
6189
6190unsigned ScalarEvolution::getSmallConstantTripCount(const Loop *L,
6191 BasicBlock *ExitingBlock) {
6192 assert(ExitingBlock && "Must pass a non-null exiting block!")((ExitingBlock && "Must pass a non-null exiting block!"
) ? static_cast<void> (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6192, __PRETTY_FUNCTION__))
;
6193 assert(L->isLoopExiting(ExitingBlock) &&((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6194, __PRETTY_FUNCTION__))
6194 "Exiting block must actually branch out of the loop!")((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6194, __PRETTY_FUNCTION__))
;
6195 const SCEVConstant *ExitCount =
6196 dyn_cast<SCEVConstant>(getExitCount(L, ExitingBlock));
6197 return getConstantTripCount(ExitCount);
6198}
6199
6200unsigned ScalarEvolution::getSmallConstantMaxTripCount(const Loop *L) {
6201 const auto *MaxExitCount =
6202 dyn_cast<SCEVConstant>(getMaxBackedgeTakenCount(L));
6203 return getConstantTripCount(MaxExitCount);
6204}
6205
6206unsigned ScalarEvolution::getSmallConstantTripMultiple(const Loop *L) {
6207 if (BasicBlock *ExitingBB = L->getExitingBlock())
6208 return getSmallConstantTripMultiple(L, ExitingBB);
6209
6210 // No trip multiple information for multiple exits.
6211 return 0;
6212}
6213
6214/// Returns the largest constant divisor of the trip count of this loop as a
6215/// normal unsigned value, if possible. This means that the actual trip count is
6216/// always a multiple of the returned value (don't forget the trip count could
6217/// very well be zero as well!).
6218///
6219/// Returns 1 if the trip count is unknown or not guaranteed to be the
6220/// multiple of a constant (which is also the case if the trip count is simply
6221/// constant, use getSmallConstantTripCount for that case), Will also return 1
6222/// if the trip count is very large (>= 2^32).
6223///
6224/// As explained in the comments for getSmallConstantTripCount, this assumes
6225/// that control exits the loop via ExitingBlock.
6226unsigned
6227ScalarEvolution::getSmallConstantTripMultiple(const Loop *L,
6228 BasicBlock *ExitingBlock) {
6229 assert(ExitingBlock && "Must pass a non-null exiting block!")((ExitingBlock && "Must pass a non-null exiting block!"
) ? static_cast<void> (0) : __assert_fail ("ExitingBlock && \"Must pass a non-null exiting block!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6229, __PRETTY_FUNCTION__))
;
6230 assert(L->isLoopExiting(ExitingBlock) &&((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6231, __PRETTY_FUNCTION__))
6231 "Exiting block must actually branch out of the loop!")((L->isLoopExiting(ExitingBlock) && "Exiting block must actually branch out of the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->isLoopExiting(ExitingBlock) && \"Exiting block must actually branch out of the loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6231, __PRETTY_FUNCTION__))
;
6232 const SCEV *ExitCount = getExitCount(L, ExitingBlock);
6233 if (ExitCount == getCouldNotCompute())
6234 return 1;
6235
6236 // Get the trip count from the BE count by adding 1.
6237 const SCEV *TCExpr = getAddExpr(ExitCount, getOne(ExitCount->getType()));
6238
6239 const SCEVConstant *TC = dyn_cast<SCEVConstant>(TCExpr);
6240 if (!TC)
6241 // Attempt to factor more general cases. Returns the greatest power of
6242 // two divisor. If overflow happens, the trip count expression is still
6243 // divisible by the greatest power of 2 divisor returned.
6244 return 1U << std::min((uint32_t)31, GetMinTrailingZeros(TCExpr));
6245
6246 ConstantInt *Result = TC->getValue();
6247
6248 // Guard against huge trip counts (this requires checking
6249 // for zero to handle the case where the trip count == -1 and the
6250 // addition wraps).
6251 if (!Result || Result->getValue().getActiveBits() > 32 ||
6252 Result->getValue().getActiveBits() == 0)
6253 return 1;
6254
6255 return (unsigned)Result->getZExtValue();
6256}
6257
6258/// Get the expression for the number of loop iterations for which this loop is
6259/// guaranteed not to exit via ExitingBlock. Otherwise return
6260/// SCEVCouldNotCompute.
6261const SCEV *ScalarEvolution::getExitCount(const Loop *L,
6262 BasicBlock *ExitingBlock) {
6263 return getBackedgeTakenInfo(L).getExact(ExitingBlock, this);
6264}
6265
6266const SCEV *
6267ScalarEvolution::getPredicatedBackedgeTakenCount(const Loop *L,
6268 SCEVUnionPredicate &Preds) {
6269 return getPredicatedBackedgeTakenInfo(L).getExact(this, &Preds);
6270}
6271
6272const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L) {
6273 return getBackedgeTakenInfo(L).getExact(this);
6274}
6275
6276/// Similar to getBackedgeTakenCount, except return the least SCEV value that is
6277/// known never to be less than the actual backedge taken count.
6278const SCEV *ScalarEvolution::getMaxBackedgeTakenCount(const Loop *L) {
6279 return getBackedgeTakenInfo(L).getMax(this);
6280}
6281
6282bool ScalarEvolution::isBackedgeTakenCountMaxOrZero(const Loop *L) {
6283 return getBackedgeTakenInfo(L).isMaxOrZero(this);
6284}
6285
6286/// Push PHI nodes in the header of the given loop onto the given Worklist.
6287static void
6288PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) {
6289 BasicBlock *Header = L->getHeader();
6290
6291 // Push all Loop-header PHIs onto the Worklist stack.
6292 for (BasicBlock::iterator I = Header->begin();
6293 PHINode *PN = dyn_cast<PHINode>(I); ++I)
6294 Worklist.push_back(PN);
6295}
6296
6297const ScalarEvolution::BackedgeTakenInfo &
6298ScalarEvolution::getPredicatedBackedgeTakenInfo(const Loop *L) {
6299 auto &BTI = getBackedgeTakenInfo(L);
6300 if (BTI.hasFullInfo())
6301 return BTI;
6302
6303 auto Pair = PredicatedBackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
6304
6305 if (!Pair.second)
6306 return Pair.first->second;
6307
6308 BackedgeTakenInfo Result =
6309 computeBackedgeTakenCount(L, /*AllowPredicates=*/true);
6310
6311 return PredicatedBackedgeTakenCounts.find(L)->second = std::move(Result);
6312}
6313
6314const ScalarEvolution::BackedgeTakenInfo &
6315ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
6316 // Initially insert an invalid entry for this loop. If the insertion
6317 // succeeds, proceed to actually compute a backedge-taken count and
6318 // update the value. The temporary CouldNotCompute value tells SCEV
6319 // code elsewhere that it shouldn't attempt to request a new
6320 // backedge-taken count, which could result in infinite recursion.
6321 std::pair<DenseMap<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
6322 BackedgeTakenCounts.insert({L, BackedgeTakenInfo()});
6323 if (!Pair.second)
6324 return Pair.first->second;
6325
6326 // computeBackedgeTakenCount may allocate memory for its result. Inserting it
6327 // into the BackedgeTakenCounts map transfers ownership. Otherwise, the result
6328 // must be cleared in this scope.
6329 BackedgeTakenInfo Result = computeBackedgeTakenCount(L);
6330
6331 if (Result.getExact(this) != getCouldNotCompute()) {
6332 assert(isLoopInvariant(Result.getExact(this), L) &&((isLoopInvariant(Result.getExact(this), L) && isLoopInvariant
(Result.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Result.getExact(this), L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6334, __PRETTY_FUNCTION__))
6333 isLoopInvariant(Result.getMax(this), L) &&((isLoopInvariant(Result.getExact(this), L) && isLoopInvariant
(Result.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Result.getExact(this), L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6334, __PRETTY_FUNCTION__))
6334 "Computed backedge-taken count isn't loop invariant for loop!")((isLoopInvariant(Result.getExact(this), L) && isLoopInvariant
(Result.getMax(this), L) && "Computed backedge-taken count isn't loop invariant for loop!"
) ? static_cast<void> (0) : __assert_fail ("isLoopInvariant(Result.getExact(this), L) && isLoopInvariant(Result.getMax(this), L) && \"Computed backedge-taken count isn't loop invariant for loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6334, __PRETTY_FUNCTION__))
;
6335 ++NumTripCountsComputed;
6336 }
6337 else if (Result.getMax(this) == getCouldNotCompute() &&
6338 isa<PHINode>(L->getHeader()->begin())) {
6339 // Only count loops that have phi nodes as not being computable.
6340 ++NumTripCountsNotComputed;
6341 }
6342
6343 // Now that we know more about the trip count for this loop, forget any
6344 // existing SCEV values for PHI nodes in this loop since they are only
6345 // conservative estimates made without the benefit of trip count
6346 // information. This is similar to the code in forgetLoop, except that
6347 // it handles SCEVUnknown PHI nodes specially.
6348 if (Result.hasAnyInfo()) {
6349 SmallVector<Instruction *, 16> Worklist;
6350 PushLoopPHIs(L, Worklist);
6351
6352 SmallPtrSet<Instruction *, 8> Visited;
6353 while (!Worklist.empty()) {
6354 Instruction *I = Worklist.pop_back_val();
6355 if (!Visited.insert(I).second)
6356 continue;
6357
6358 ValueExprMapType::iterator It =
6359 ValueExprMap.find_as(static_cast<Value *>(I));
6360 if (It != ValueExprMap.end()) {
6361 const SCEV *Old = It->second;
6362
6363 // SCEVUnknown for a PHI either means that it has an unrecognized
6364 // structure, or it's a PHI that's in the progress of being computed
6365 // by createNodeForPHI. In the former case, additional loop trip
6366 // count information isn't going to change anything. In the later
6367 // case, createNodeForPHI will perform the necessary updates on its
6368 // own when it gets to that point.
6369 if (!isa<PHINode>(I) || !isa<SCEVUnknown>(Old)) {
6370 eraseValueFromMap(It->first);
6371 forgetMemoizedResults(Old, false);
6372 }
6373 if (PHINode *PN = dyn_cast<PHINode>(I))
6374 ConstantEvolutionLoopExitValue.erase(PN);
6375 }
6376
6377 PushDefUseChildren(I, Worklist);
6378 }
6379 }
6380
6381 // Re-lookup the insert position, since the call to
6382 // computeBackedgeTakenCount above could result in a
6383 // recusive call to getBackedgeTakenInfo (on a different
6384 // loop), which would invalidate the iterator computed
6385 // earlier.
6386 return BackedgeTakenCounts.find(L)->second = std::move(Result);
6387}
6388
6389void ScalarEvolution::forgetLoop(const Loop *L) {
6390 // Drop any stored trip count value.
6391 auto RemoveLoopFromBackedgeMap =
6392 [](DenseMap<const Loop *, BackedgeTakenInfo> &Map, const Loop *L) {
6393 auto BTCPos = Map.find(L);
6394 if (BTCPos != Map.end()) {
6395 BTCPos->second.clear();
6396 Map.erase(BTCPos);
6397 }
6398 };
6399
6400 SmallVector<const Loop *, 16> LoopWorklist(1, L);
6401 SmallVector<Instruction *, 32> Worklist;
6402 SmallPtrSet<Instruction *, 16> Visited;
6403
6404 // Iterate over all the loops and sub-loops to drop SCEV information.
6405 while (!LoopWorklist.empty()) {
6406 auto *CurrL = LoopWorklist.pop_back_val();
6407
6408 RemoveLoopFromBackedgeMap(BackedgeTakenCounts, CurrL);
6409 RemoveLoopFromBackedgeMap(PredicatedBackedgeTakenCounts, CurrL);
6410
6411 // Drop information about predicated SCEV rewrites for this loop.
6412 for (auto I = PredicatedSCEVRewrites.begin();
6413 I != PredicatedSCEVRewrites.end();) {
6414 std::pair<const SCEV *, const Loop *> Entry = I->first;
6415 if (Entry.second == CurrL)
6416 PredicatedSCEVRewrites.erase(I++);
6417 else
6418 ++I;
6419 }
6420
6421 auto LoopUsersItr = LoopUsers.find(CurrL);
6422 if (LoopUsersItr != LoopUsers.end()) {
6423 for (auto *S : LoopUsersItr->second)
6424 forgetMemoizedResults(S);
6425 LoopUsers.erase(LoopUsersItr);
6426 }
6427
6428 // Drop information about expressions based on loop-header PHIs.
6429 PushLoopPHIs(CurrL, Worklist);
6430
6431 while (!Worklist.empty()) {
6432 Instruction *I = Worklist.pop_back_val();
6433 if (!Visited.insert(I).second)
6434 continue;
6435
6436 ValueExprMapType::iterator It =
6437 ValueExprMap.find_as(static_cast<Value *>(I));
6438 if (It != ValueExprMap.end()) {
6439 eraseValueFromMap(It->first);
6440 forgetMemoizedResults(It->second);
6441 if (PHINode *PN = dyn_cast<PHINode>(I))
6442 ConstantEvolutionLoopExitValue.erase(PN);
6443 }
6444
6445 PushDefUseChildren(I, Worklist);
6446 }
6447
6448 for (auto I = ExitLimits.begin(); I != ExitLimits.end(); ++I) {
6449 auto &Query = I->first;
6450 if (Query.L == CurrL)
6451 ExitLimits.erase(I);
6452 }
6453
6454 LoopPropertiesCache.erase(CurrL);
6455 // Forget all contained loops too, to avoid dangling entries in the
6456 // ValuesAtScopes map.
6457 LoopWorklist.append(CurrL->begin(), CurrL->end());
6458 }
6459}
6460
6461
6462const SCEV *ScalarEvolution::evaluateForICmp(ICmpInst *IC) {
6463 BasicBlock *Latch = nullptr;
6464 const Loop *L = LI.getLoopFor(IC->getParent());
6465
6466 // If compare instruction is same or inverse of the compare in the
6467 // branch of the loop latch, then return a constant evolution
6468 // node. This shall facilitate computations of loop exit counts
6469 // in cases where compare appears in the evolution chain of induction
6470 // variables.
6471 if (L && (Latch = L->getLoopLatch())) {
6472 BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator());
6473 if (BI && BI->isConditional() && BI->getCondition() == IC) {
6474 if (BI->getSuccessor(0) != L->getHeader())
6475 return getZero(Type::getInt1Ty(getContext()));
6476 else
6477 return getOne(Type::getInt1Ty(getContext()));
6478 }
6479 }
6480
6481 return getUnknown(IC);
6482}
6483
6484
6485void ScalarEvolution::forgetValue(Value *V) {
6486 Instruction *I = dyn_cast<Instruction>(V);
6487 if (!I) return;
6488
6489 // Drop information about expressions based on loop-header PHIs.
6490 SmallVector<Instruction *, 16> Worklist;
6491 Worklist.push_back(I);
6492
6493 SmallPtrSet<Instruction *, 8> Visited;
6494 while (!Worklist.empty()) {
6495 I = Worklist.pop_back_val();
6496 if (!Visited.insert(I).second)
6497 continue;
6498
6499 ValueExprMapType::iterator It =
6500 ValueExprMap.find_as(static_cast<Value *>(I));
6501 if (It != ValueExprMap.end()) {
6502 eraseValueFromMap(It->first);
6503 forgetMemoizedResults(It->second);
6504 if (PHINode *PN = dyn_cast<PHINode>(I))
6505 ConstantEvolutionLoopExitValue.erase(PN);
6506 }
6507
6508 PushDefUseChildren(I, Worklist);
6509 }
6510}
6511
6512/// Get the exact loop backedge taken count considering all loop exits. A
6513/// computable result can only be returned for loops with a single exit.
6514/// Returning the minimum taken count among all exits is incorrect because one
6515/// of the loop's exit limit's may have been skipped. howFarToZero assumes that
6516/// the limit of each loop test is never skipped. This is a valid assumption as
6517/// long as the loop exits via that test. For precise results, it is the
6518/// caller's responsibility to specify the relevant loop exit using
6519/// getExact(ExitingBlock, SE).
6520const SCEV *
6521ScalarEvolution::BackedgeTakenInfo::getExact(ScalarEvolution *SE,
6522 SCEVUnionPredicate *Preds) const {
6523 // If any exits were not computable, the loop is not computable.
6524 if (!isComplete() || ExitNotTaken.empty())
6525 return SE->getCouldNotCompute();
6526
6527 const SCEV *BECount = nullptr;
6528 for (auto &ENT : ExitNotTaken) {
6529 assert(ENT.ExactNotTaken != SE->getCouldNotCompute() && "bad exit SCEV")((ENT.ExactNotTaken != SE->getCouldNotCompute() &&
"bad exit SCEV") ? static_cast<void> (0) : __assert_fail
("ENT.ExactNotTaken != SE->getCouldNotCompute() && \"bad exit SCEV\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6529, __PRETTY_FUNCTION__))
;
6530
6531 if (!BECount)
6532 BECount = ENT.ExactNotTaken;
6533 else if (BECount != ENT.ExactNotTaken)
6534 return SE->getCouldNotCompute();
6535 if (Preds && !ENT.hasAlwaysTruePredicate())
6536 Preds->add(ENT.Predicate.get());
6537
6538 assert((Preds || ENT.hasAlwaysTruePredicate()) &&(((Preds || ENT.hasAlwaysTruePredicate()) && "Predicate should be always true!"
) ? static_cast<void> (0) : __assert_fail ("(Preds || ENT.hasAlwaysTruePredicate()) && \"Predicate should be always true!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6539, __PRETTY_FUNCTION__))
6539 "Predicate should be always true!")(((Preds || ENT.hasAlwaysTruePredicate()) && "Predicate should be always true!"
) ? static_cast<void> (0) : __assert_fail ("(Preds || ENT.hasAlwaysTruePredicate()) && \"Predicate should be always true!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6539, __PRETTY_FUNCTION__))
;
6540 }
6541
6542 assert(BECount && "Invalid not taken count for loop exit")((BECount && "Invalid not taken count for loop exit")
? static_cast<void> (0) : __assert_fail ("BECount && \"Invalid not taken count for loop exit\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6542, __PRETTY_FUNCTION__))
;
6543 return BECount;
6544}
6545
6546/// Get the exact not taken count for this loop exit.
6547const SCEV *
6548ScalarEvolution::BackedgeTakenInfo::getExact(BasicBlock *ExitingBlock,
6549 ScalarEvolution *SE) const {
6550 for (auto &ENT : ExitNotTaken)
6551 if (ENT.ExitingBlock == ExitingBlock && ENT.hasAlwaysTruePredicate())
6552 return ENT.ExactNotTaken;
6553
6554 return SE->getCouldNotCompute();
6555}
6556
6557/// getMax - Get the max backedge taken count for the loop.
6558const SCEV *
6559ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const {
6560 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
6561 return !ENT.hasAlwaysTruePredicate();
6562 };
6563
6564 if (any_of(ExitNotTaken, PredicateNotAlwaysTrue) || !getMax())
6565 return SE->getCouldNotCompute();
6566
6567 assert((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) &&(((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant
>(getMax())) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6568, __PRETTY_FUNCTION__))
6568 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant
>(getMax())) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(getMax()) || isa<SCEVConstant>(getMax())) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6568, __PRETTY_FUNCTION__))
;
6569 return getMax();
6570}
6571
6572bool ScalarEvolution::BackedgeTakenInfo::isMaxOrZero(ScalarEvolution *SE) const {
6573 auto PredicateNotAlwaysTrue = [](const ExitNotTakenInfo &ENT) {
6574 return !ENT.hasAlwaysTruePredicate();
6575 };
6576 return MaxOrZero && !any_of(ExitNotTaken, PredicateNotAlwaysTrue);
6577}
6578
6579bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S,
6580 ScalarEvolution *SE) const {
6581 if (getMax() && getMax() != SE->getCouldNotCompute() &&
6582 SE->hasOperand(getMax(), S))
6583 return true;
6584
6585 for (auto &ENT : ExitNotTaken)
6586 if (ENT.ExactNotTaken != SE->getCouldNotCompute() &&
6587 SE->hasOperand(ENT.ExactNotTaken, S))
6588 return true;
6589
6590 return false;
6591}
6592
6593ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E)
6594 : ExactNotTaken(E), MaxNotTaken(E) {
6595 assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6597, __PRETTY_FUNCTION__))
6596 isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6597, __PRETTY_FUNCTION__))
6597 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6597, __PRETTY_FUNCTION__))
;
6598}
6599
6600ScalarEvolution::ExitLimit::ExitLimit(
6601 const SCEV *E, const SCEV *M, bool MaxOrZero,
6602 ArrayRef<const SmallPtrSetImpl<const SCEVPredicate *> *> PredSetList)
6603 : ExactNotTaken(E), MaxNotTaken(M), MaxOrZero(MaxOrZero) {
6604 assert((isa<SCEVCouldNotCompute>(ExactNotTaken) ||(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute
>(MaxNotTaken)) && "Exact is not allowed to be less precise than Max"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6606, __PRETTY_FUNCTION__))
6605 !isa<SCEVCouldNotCompute>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute
>(MaxNotTaken)) && "Exact is not allowed to be less precise than Max"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6606, __PRETTY_FUNCTION__))
6606 "Exact is not allowed to be less precise than Max")(((isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute
>(MaxNotTaken)) && "Exact is not allowed to be less precise than Max"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(ExactNotTaken) || !isa<SCEVCouldNotCompute>(MaxNotTaken)) && \"Exact is not allowed to be less precise than Max\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6606, __PRETTY_FUNCTION__))
;
6607 assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6609, __PRETTY_FUNCTION__))
6608 isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6609, __PRETTY_FUNCTION__))
6609 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6609, __PRETTY_FUNCTION__))
;
6610 for (auto *PredSet : PredSetList)
6611 for (auto *P : *PredSet)
6612 addPredicate(P);
6613}
6614
6615ScalarEvolution::ExitLimit::ExitLimit(
6616 const SCEV *E, const SCEV *M, bool MaxOrZero,
6617 const SmallPtrSetImpl<const SCEVPredicate *> &PredSet)
6618 : ExitLimit(E, M, MaxOrZero, {&PredSet}) {
6619 assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6621, __PRETTY_FUNCTION__))
6620 isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6621, __PRETTY_FUNCTION__))
6621 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6621, __PRETTY_FUNCTION__))
;
6622}
6623
6624ScalarEvolution::ExitLimit::ExitLimit(const SCEV *E, const SCEV *M,
6625 bool MaxOrZero)
6626 : ExitLimit(E, M, MaxOrZero, None) {
6627 assert((isa<SCEVCouldNotCompute>(MaxNotTaken) ||(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6629, __PRETTY_FUNCTION__))
6628 isa<SCEVConstant>(MaxNotTaken)) &&(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6629, __PRETTY_FUNCTION__))
6629 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant
>(MaxNotTaken)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxNotTaken) || isa<SCEVConstant>(MaxNotTaken)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6629, __PRETTY_FUNCTION__))
;
6630}
6631
6632/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
6633/// computable exit into a persistent ExitNotTakenInfo array.
6634ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
6635 SmallVectorImpl<ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo>
6636 &&ExitCounts,
6637 bool Complete, const SCEV *MaxCount, bool MaxOrZero)
6638 : MaxAndComplete(MaxCount, Complete), MaxOrZero(MaxOrZero) {
6639 using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo;
6640
6641 ExitNotTaken.reserve(ExitCounts.size());
6642 std::transform(
6643 ExitCounts.begin(), ExitCounts.end(), std::back_inserter(ExitNotTaken),
6644 [&](const EdgeExitInfo &EEI) {
6645 BasicBlock *ExitBB = EEI.first;
6646 const ExitLimit &EL = EEI.second;
6647 if (EL.Predicates.empty())
6648 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, nullptr);
6649
6650 std::unique_ptr<SCEVUnionPredicate> Predicate(new SCEVUnionPredicate);
6651 for (auto *Pred : EL.Predicates)
6652 Predicate->add(Pred);
6653
6654 return ExitNotTakenInfo(ExitBB, EL.ExactNotTaken, std::move(Predicate));
6655 });
6656 assert((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) &&(((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant
>(MaxCount)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6657, __PRETTY_FUNCTION__))
6657 "No point in having a non-constant max backedge taken count!")(((isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant
>(MaxCount)) && "No point in having a non-constant max backedge taken count!"
) ? static_cast<void> (0) : __assert_fail ("(isa<SCEVCouldNotCompute>(MaxCount) || isa<SCEVConstant>(MaxCount)) && \"No point in having a non-constant max backedge taken count!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6657, __PRETTY_FUNCTION__))
;
6658}
6659
6660/// Invalidate this result and free the ExitNotTakenInfo array.
6661void ScalarEvolution::BackedgeTakenInfo::clear() {
6662 ExitNotTaken.clear();
6663}
6664
6665/// Compute the number of times the backedge of the specified loop will execute.
6666ScalarEvolution::BackedgeTakenInfo
6667ScalarEvolution::computeBackedgeTakenCount(const Loop *L,
6668 bool AllowPredicates) {
6669 SmallVector<BasicBlock *, 8> ExitingBlocks;
6670 L->getExitingBlocks(ExitingBlocks);
6671
6672 using EdgeExitInfo = ScalarEvolution::BackedgeTakenInfo::EdgeExitInfo;
6673
6674 SmallVector<EdgeExitInfo, 4> ExitCounts;
6675 bool CouldComputeBECount = true;
6676 BasicBlock *Latch = L->getLoopLatch(); // may be NULL.
6677 const SCEV *MustExitMaxBECount = nullptr;
6678 const SCEV *MayExitMaxBECount = nullptr;
6679 bool MustExitMaxOrZero = false;
6680
6681 // Compute the ExitLimit for each loop exit. Use this to populate ExitCounts
6682 // and compute maxBECount.
6683 // Do a union of all the predicates here.
6684 for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
6685 BasicBlock *ExitBB = ExitingBlocks[i];
6686 ExitLimit EL = computeExitLimit(L, ExitBB, AllowPredicates);
6687
6688 assert((AllowPredicates || EL.Predicates.empty()) &&(((AllowPredicates || EL.Predicates.empty()) && "Predicated exit limit when predicates are not allowed!"
) ? static_cast<void> (0) : __assert_fail ("(AllowPredicates || EL.Predicates.empty()) && \"Predicated exit limit when predicates are not allowed!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6689, __PRETTY_FUNCTION__))
6689 "Predicated exit limit when predicates are not allowed!")(((AllowPredicates || EL.Predicates.empty()) && "Predicated exit limit when predicates are not allowed!"
) ? static_cast<void> (0) : __assert_fail ("(AllowPredicates || EL.Predicates.empty()) && \"Predicated exit limit when predicates are not allowed!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6689, __PRETTY_FUNCTION__))
;
6690
6691 // 1. For each exit that can be computed, add an entry to ExitCounts.
6692 // CouldComputeBECount is true only if all exits can be computed.
6693 if (EL.ExactNotTaken == getCouldNotCompute())
6694 // We couldn't compute an exact value for this exit, so
6695 // we won't be able to compute an exact value for the loop.
6696 CouldComputeBECount = false;
6697 else
6698 ExitCounts.emplace_back(ExitBB, EL);
6699
6700 // 2. Derive the loop's MaxBECount from each exit's max number of
6701 // non-exiting iterations. Partition the loop exits into two kinds:
6702 // LoopMustExits and LoopMayExits.
6703 //
6704 // If the exit dominates the loop latch, it is a LoopMustExit otherwise it
6705 // is a LoopMayExit. If any computable LoopMustExit is found, then
6706 // MaxBECount is the minimum EL.MaxNotTaken of computable
6707 // LoopMustExits. Otherwise, MaxBECount is conservatively the maximum
6708 // EL.MaxNotTaken, where CouldNotCompute is considered greater than any
6709 // computable EL.MaxNotTaken.
6710 if (EL.MaxNotTaken != getCouldNotCompute() && Latch &&
6711 DT.dominates(ExitBB, Latch)) {
6712 if (!MustExitMaxBECount) {
6713 MustExitMaxBECount = EL.MaxNotTaken;
6714 MustExitMaxOrZero = EL.MaxOrZero;
6715 } else {
6716 MustExitMaxBECount =
6717 getUMinFromMismatchedTypes(MustExitMaxBECount, EL.MaxNotTaken);
6718 }
6719 } else if (MayExitMaxBECount != getCouldNotCompute()) {
6720 if (!MayExitMaxBECount || EL.MaxNotTaken == getCouldNotCompute())
6721 MayExitMaxBECount = EL.MaxNotTaken;
6722 else {
6723 MayExitMaxBECount =
6724 getUMaxFromMismatchedTypes(MayExitMaxBECount, EL.MaxNotTaken);
6725 }
6726 }
6727 }
6728 const SCEV *MaxBECount = MustExitMaxBECount ? MustExitMaxBECount :
6729 (MayExitMaxBECount ? MayExitMaxBECount : getCouldNotCompute());
6730 // The loop backedge will be taken the maximum or zero times if there's
6731 // a single exit that must be taken the maximum or zero times.
6732 bool MaxOrZero = (MustExitMaxOrZero && ExitingBlocks.size() == 1);
6733 return BackedgeTakenInfo(std::move(ExitCounts), CouldComputeBECount,
6734 MaxBECount, MaxOrZero);
6735}
6736
6737ScalarEvolution::ExitLimit
6738ScalarEvolution::computeExitLimit(const Loop *L, BasicBlock *ExitingBlock,
6739 bool AllowPredicates) {
6740 ExitLimitQuery Query(L, ExitingBlock, AllowPredicates);
6741 auto MaybeEL = ExitLimits.find(Query);
6742 if (MaybeEL != ExitLimits.end())
6743 return MaybeEL->second;
6744 ExitLimit EL = computeExitLimitImpl(L, ExitingBlock, AllowPredicates);
6745 ExitLimits.insert({Query, EL});
6746 return EL;
6747}
6748
6749ScalarEvolution::ExitLimit
6750ScalarEvolution::computeExitLimitImpl(const Loop *L, BasicBlock *ExitingBlock,
6751 bool AllowPredicates) {
6752 // Okay, we've chosen an exiting block. See what condition causes us to exit
6753 // at this block and remember the exit block and whether all other targets
6754 // lead to the loop header.
6755 bool MustExecuteLoopHeader = true;
6756 BasicBlock *Exit = nullptr;
6757 for (auto *SBB : successors(ExitingBlock))
6758 if (!L->contains(SBB)) {
6759 if (Exit) // Multiple exit successors.
6760 return getCouldNotCompute();
6761 Exit = SBB;
6762 } else if (SBB != L->getHeader()) {
6763 MustExecuteLoopHeader = false;
6764 }
6765
6766 // At this point, we know we have a conditional branch that determines whether
6767 // the loop is exited. However, we don't know if the branch is executed each
6768 // time through the loop. If not, then the execution count of the branch will
6769 // not be equal to the trip count of the loop.
6770 //
6771 // Currently we check for this by checking to see if the Exit branch goes to
6772 // the loop header. If so, we know it will always execute the same number of
6773 // times as the loop. We also handle the case where the exit block *is* the
6774 // loop header. This is common for un-rotated loops.
6775 //
6776 // If both of those tests fail, walk up the unique predecessor chain to the
6777 // header, stopping if there is an edge that doesn't exit the loop. If the
6778 // header is reached, the execution count of the branch will be equal to the
6779 // trip count of the loop.
6780 //
6781 // More extensive analysis could be done to handle more cases here.
6782 //
6783 if (!MustExecuteLoopHeader && ExitingBlock != L->getHeader()) {
6784 // The simple checks failed, try climbing the unique predecessor chain
6785 // up to the header.
6786 bool Ok = false;
6787 for (BasicBlock *BB = ExitingBlock; BB; ) {
6788 BasicBlock *Pred = BB->getUniquePredecessor();
6789 if (!Pred)
6790 return getCouldNotCompute();
6791 TerminatorInst *PredTerm = Pred->getTerminator();
6792 for (const BasicBlock *PredSucc : PredTerm->successors()) {
6793 if (PredSucc == BB)
6794 continue;
6795 // If the predecessor has a successor that isn't BB and isn't
6796 // outside the loop, assume the worst.
6797 if (L->contains(PredSucc))
6798 return getCouldNotCompute();
6799 }
6800 if (Pred == L->getHeader()) {
6801 Ok = true;
6802 break;
6803 }
6804 BB = Pred;
6805 }
6806 if (!Ok)
6807 return getCouldNotCompute();
6808 }
6809
6810 bool IsOnlyExit = (L->getExitingBlock() != nullptr);
6811 TerminatorInst *Term = ExitingBlock->getTerminator();
6812 if (BranchInst *BI = dyn_cast<BranchInst>(Term)) {
6813 assert(BI->isConditional() && "If unconditional, it can't be in loop!")((BI->isConditional() && "If unconditional, it can't be in loop!"
) ? static_cast<void> (0) : __assert_fail ("BI->isConditional() && \"If unconditional, it can't be in loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6813, __PRETTY_FUNCTION__))
;
6814 // Proceed to the next level to examine the exit condition expression.
6815 return computeExitLimitFromCond(
6816 L, BI->getCondition(), BI->getSuccessor(0), BI->getSuccessor(1),
6817 /*ControlsExit=*/IsOnlyExit, AllowPredicates);
6818 }
6819
6820 if (SwitchInst *SI = dyn_cast<SwitchInst>(Term))
6821 return computeExitLimitFromSingleExitSwitch(L, SI, Exit,
6822 /*ControlsExit=*/IsOnlyExit);
6823
6824 return getCouldNotCompute();
6825}
6826
6827ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCond(
6828 const Loop *L, Value *ExitCond, BasicBlock *TBB, BasicBlock *FBB,
6829 bool ControlsExit, bool AllowPredicates) {
6830 ScalarEvolution::ExitLimitCacheTy Cache(L, TBB, FBB, AllowPredicates);
6831 return computeExitLimitFromCondCached(Cache, L, ExitCond, TBB, FBB,
6832 ControlsExit, AllowPredicates);
6833}
6834
6835Optional<ScalarEvolution::ExitLimit>
6836ScalarEvolution::ExitLimitCache::find(const Loop *L, Value *ExitCond,
6837 BasicBlock *TBB, BasicBlock *FBB,
6838 bool ControlsExit, bool AllowPredicates) {
6839 (void)this->L;
6840 (void)this->TBB;
6841 (void)this->FBB;
6842 (void)this->AllowPredicates;
6843
6844 assert(this->L == L && this->TBB == TBB && this->FBB == FBB &&((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6846, __PRETTY_FUNCTION__))
6845 this->AllowPredicates == AllowPredicates &&((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6846, __PRETTY_FUNCTION__))
6846 "Variance in assumed invariant key components!")((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6846, __PRETTY_FUNCTION__))
;
6847 auto Itr = TripCountMap.find({ExitCond, ControlsExit});
6848 if (Itr == TripCountMap.end())
6849 return None;
6850 return Itr->second;
6851}
6852
6853void ScalarEvolution::ExitLimitCache::insert(const Loop *L, Value *ExitCond,
6854 BasicBlock *TBB, BasicBlock *FBB,
6855 bool ControlsExit,
6856 bool AllowPredicates,
6857 const ExitLimit &EL) {
6858 assert(this->L == L && this->TBB == TBB && this->FBB == FBB &&((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6860, __PRETTY_FUNCTION__))
6859 this->AllowPredicates == AllowPredicates &&((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6860, __PRETTY_FUNCTION__))
6860 "Variance in assumed invariant key components!")((this->L == L && this->TBB == TBB && this
->FBB == FBB && this->AllowPredicates == AllowPredicates
&& "Variance in assumed invariant key components!") ?
static_cast<void> (0) : __assert_fail ("this->L == L && this->TBB == TBB && this->FBB == FBB && this->AllowPredicates == AllowPredicates && \"Variance in assumed invariant key components!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6860, __PRETTY_FUNCTION__))
;
6861
6862 auto InsertResult = TripCountMap.insert({{ExitCond, ControlsExit}, EL});
6863 assert(InsertResult.second && "Expected successful insertion!")((InsertResult.second && "Expected successful insertion!"
) ? static_cast<void> (0) : __assert_fail ("InsertResult.second && \"Expected successful insertion!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6863, __PRETTY_FUNCTION__))
;
6864 (void)InsertResult;
6865}
6866
6867ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondCached(
6868 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, BasicBlock *TBB,
6869 BasicBlock *FBB, bool ControlsExit, bool AllowPredicates) {
6870
6871 if (auto MaybeEL =
6872 Cache.find(L, ExitCond, TBB, FBB, ControlsExit, AllowPredicates))
6873 return *MaybeEL;
6874
6875 ExitLimit EL = computeExitLimitFromCondImpl(Cache, L, ExitCond, TBB, FBB,
6876 ControlsExit, AllowPredicates);
6877 Cache.insert(L, ExitCond, TBB, FBB, ControlsExit, AllowPredicates, EL);
6878 return EL;
6879}
6880
6881ScalarEvolution::ExitLimit ScalarEvolution::computeExitLimitFromCondImpl(
6882 ExitLimitCacheTy &Cache, const Loop *L, Value *ExitCond, BasicBlock *TBB,
6883 BasicBlock *FBB, bool ControlsExit, bool AllowPredicates) {
6884 // Check if the controlling expression for this loop is an And or Or.
6885 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) {
6886 if (BO->getOpcode() == Instruction::And) {
6887 // Recurse on the operands of the and.
6888 bool EitherMayExit = L->contains(TBB);
6889 ExitLimit EL0 = computeExitLimitFromCondCached(
6890 Cache, L, BO->getOperand(0), TBB, FBB, ControlsExit && !EitherMayExit,
6891 AllowPredicates);
6892 ExitLimit EL1 = computeExitLimitFromCondCached(
6893 Cache, L, BO->getOperand(1), TBB, FBB, ControlsExit && !EitherMayExit,
6894 AllowPredicates);
6895 const SCEV *BECount = getCouldNotCompute();
6896 const SCEV *MaxBECount = getCouldNotCompute();
6897 if (EitherMayExit) {
6898 // Both conditions must be true for the loop to continue executing.
6899 // Choose the less conservative count.
6900 if (EL0.ExactNotTaken == getCouldNotCompute() ||
6901 EL1.ExactNotTaken == getCouldNotCompute())
6902 BECount = getCouldNotCompute();
6903 else
6904 BECount =
6905 getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken);
6906 if (EL0.MaxNotTaken == getCouldNotCompute())
6907 MaxBECount = EL1.MaxNotTaken;
6908 else if (EL1.MaxNotTaken == getCouldNotCompute())
6909 MaxBECount = EL0.MaxNotTaken;
6910 else
6911 MaxBECount =
6912 getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
6913 } else {
6914 // Both conditions must be true at the same time for the loop to exit.
6915 // For now, be conservative.
6916 assert(L->contains(FBB) && "Loop block has no successor in loop!")((L->contains(FBB) && "Loop block has no successor in loop!"
) ? static_cast<void> (0) : __assert_fail ("L->contains(FBB) && \"Loop block has no successor in loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6916, __PRETTY_FUNCTION__))
;
6917 if (EL0.MaxNotTaken == EL1.MaxNotTaken)
6918 MaxBECount = EL0.MaxNotTaken;
6919 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
6920 BECount = EL0.ExactNotTaken;
6921 }
6922
6923 // There are cases (e.g. PR26207) where computeExitLimitFromCond is able
6924 // to be more aggressive when computing BECount than when computing
6925 // MaxBECount. In these cases it is possible for EL0.ExactNotTaken and
6926 // EL1.ExactNotTaken to match, but for EL0.MaxNotTaken and EL1.MaxNotTaken
6927 // to not.
6928 if (isa<SCEVCouldNotCompute>(MaxBECount) &&
6929 !isa<SCEVCouldNotCompute>(BECount))
6930 MaxBECount = getConstant(getUnsignedRangeMax(BECount));
6931
6932 return ExitLimit(BECount, MaxBECount, false,
6933 {&EL0.Predicates, &EL1.Predicates});
6934 }
6935 if (BO->getOpcode() == Instruction::Or) {
6936 // Recurse on the operands of the or.
6937 bool EitherMayExit = L->contains(FBB);
6938 ExitLimit EL0 = computeExitLimitFromCondCached(
6939 Cache, L, BO->getOperand(0), TBB, FBB, ControlsExit && !EitherMayExit,
6940 AllowPredicates);
6941 ExitLimit EL1 = computeExitLimitFromCondCached(
6942 Cache, L, BO->getOperand(1), TBB, FBB, ControlsExit && !EitherMayExit,
6943 AllowPredicates);
6944 const SCEV *BECount = getCouldNotCompute();
6945 const SCEV *MaxBECount = getCouldNotCompute();
6946 if (EitherMayExit) {
6947 // Both conditions must be false for the loop to continue executing.
6948 // Choose the less conservative count.
6949 if (EL0.ExactNotTaken == getCouldNotCompute() ||
6950 EL1.ExactNotTaken == getCouldNotCompute())
6951 BECount = getCouldNotCompute();
6952 else
6953 BECount =
6954 getUMinFromMismatchedTypes(EL0.ExactNotTaken, EL1.ExactNotTaken);
6955 if (EL0.MaxNotTaken == getCouldNotCompute())
6956 MaxBECount = EL1.MaxNotTaken;
6957 else if (EL1.MaxNotTaken == getCouldNotCompute())
6958 MaxBECount = EL0.MaxNotTaken;
6959 else
6960 MaxBECount =
6961 getUMinFromMismatchedTypes(EL0.MaxNotTaken, EL1.MaxNotTaken);
6962 } else {
6963 // Both conditions must be false at the same time for the loop to exit.
6964 // For now, be conservative.
6965 assert(L->contains(TBB) && "Loop block has no successor in loop!")((L->contains(TBB) && "Loop block has no successor in loop!"
) ? static_cast<void> (0) : __assert_fail ("L->contains(TBB) && \"Loop block has no successor in loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 6965, __PRETTY_FUNCTION__))
;
6966 if (EL0.MaxNotTaken == EL1.MaxNotTaken)
6967 MaxBECount = EL0.MaxNotTaken;
6968 if (EL0.ExactNotTaken == EL1.ExactNotTaken)
6969 BECount = EL0.ExactNotTaken;
6970 }
6971
6972 return ExitLimit(BECount, MaxBECount, false,
6973 {&EL0.Predicates, &EL1.Predicates});
6974 }
6975 }
6976
6977 // With an icmp, it may be feasible to compute an exact backedge-taken count.
6978 // Proceed to the next level to examine the icmp.
6979 if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond)) {
6980 ExitLimit EL =
6981 computeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit);
6982 if (EL.hasFullInfo() || !AllowPredicates)
6983 return EL;
6984
6985 // Try again, but use SCEV predicates this time.
6986 return computeExitLimitFromICmp(L, ExitCondICmp, TBB, FBB, ControlsExit,
6987 /*AllowPredicates=*/true);
6988 }
6989
6990 // Check for a constant condition. These are normally stripped out by
6991 // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
6992 // preserve the CFG and is temporarily leaving constant conditions
6993 // in place.
6994 if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) {
6995 if (L->contains(FBB) == !CI->getZExtValue())
6996 // The backedge is always taken.
6997 return getCouldNotCompute();
6998 else
6999 // The backedge is never taken.
7000 return getZero(CI->getType());
7001 }
7002
7003 // If it's not an integer or pointer comparison then compute it the hard way.
7004 return computeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
7005}
7006
7007ScalarEvolution::ExitLimit
7008ScalarEvolution::computeExitLimitFromICmp(const Loop *L,
7009 ICmpInst *ExitCond,
7010 BasicBlock *TBB,
7011 BasicBlock *FBB,
7012 bool ControlsExit,
7013 bool AllowPredicates) {
7014 // If the condition was exit on true, convert the condition to exit on false
7015 ICmpInst::Predicate Cond;
7016 if (!L->contains(FBB))
7017 Cond = ExitCond->getPredicate();
7018 else
7019 Cond = ExitCond->getInversePredicate();
7020
7021 // Handle common loops like: for (X = "string"; *X; ++X)
7022 if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
7023 if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) {
7024 ExitLimit ItCnt =
7025 computeLoadConstantCompareExitLimit(LI, RHS, L, Cond);
7026 if (ItCnt.hasAnyInfo())
7027 return ItCnt;
7028 }
7029
7030 const SCEV *LHS = getSCEV(ExitCond->getOperand(0));
7031 const SCEV *RHS = getSCEV(ExitCond->getOperand(1));
7032
7033 // Try to evaluate any dependencies out of the loop.
7034 LHS = getSCEVAtScope(LHS, L);
7035 RHS = getSCEVAtScope(RHS, L);
7036
7037 // At this point, we would like to compute how many iterations of the
7038 // loop the predicate will return true for these inputs.
7039 if (isLoopInvariant(LHS, L) && !isLoopInvariant(RHS, L)) {
7040 // If there is a loop-invariant, force it into the RHS.
7041 std::swap(LHS, RHS);
7042 Cond = ICmpInst::getSwappedPredicate(Cond);
7043 }
7044
7045 // Simplify the operands before analyzing them.
7046 (void)SimplifyICmpOperands(Cond, LHS, RHS);
7047
7048 // If we have a comparison of a chrec against a constant, try to use value
7049 // ranges to answer this query.
7050 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
7051 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS))
7052 if (AddRec->getLoop() == L) {
7053 // Form the constant range.
7054 ConstantRange CompRange =
7055 ConstantRange::makeExactICmpRegion(Cond, RHSC->getAPInt());
7056
7057 const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this);
7058 if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
7059 }
7060
7061 switch (Cond) {
7062 case ICmpInst::ICMP_NE: { // while (X != Y)
7063 // Convert to: while (X-Y != 0)
7064 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit,
7065 AllowPredicates);
7066 if (EL.hasAnyInfo()) return EL;
7067 break;
7068 }
7069 case ICmpInst::ICMP_EQ: { // while (X == Y)
7070 // Convert to: while (X-Y == 0)
7071 ExitLimit EL = howFarToNonZero(getMinusSCEV(LHS, RHS), L);
7072 if (EL.hasAnyInfo()) return EL;
7073 break;
7074 }
7075 case ICmpInst::ICMP_SLT:
7076 case ICmpInst::ICMP_ULT: { // while (X < Y)
7077 bool IsSigned = Cond == ICmpInst::ICMP_SLT;
7078 ExitLimit EL = howManyLessThans(LHS, RHS, L, IsSigned, ControlsExit,
7079 AllowPredicates);
7080 if (EL.hasAnyInfo()) return EL;
7081 break;
7082 }
7083 case ICmpInst::ICMP_SGT:
7084 case ICmpInst::ICMP_UGT: { // while (X > Y)
7085 bool IsSigned = Cond == ICmpInst::ICMP_SGT;
7086 ExitLimit EL =
7087 howManyGreaterThans(LHS, RHS, L, IsSigned, ControlsExit,
7088 AllowPredicates);
7089 if (EL.hasAnyInfo()) return EL;
7090 break;
7091 }
7092 default:
7093 break;
7094 }
7095
7096 auto *ExhaustiveCount =
7097 computeExitCountExhaustively(L, ExitCond, !L->contains(TBB));
7098
7099 if (!isa<SCEVCouldNotCompute>(ExhaustiveCount))
7100 return ExhaustiveCount;
7101
7102 return computeShiftCompareExitLimit(ExitCond->getOperand(0),
7103 ExitCond->getOperand(1), L, Cond);
7104}
7105
7106ScalarEvolution::ExitLimit
7107ScalarEvolution::computeExitLimitFromSingleExitSwitch(const Loop *L,
7108 SwitchInst *Switch,
7109 BasicBlock *ExitingBlock,
7110 bool ControlsExit) {
7111 assert(!L->contains(ExitingBlock) && "Not an exiting block!")((!L->contains(ExitingBlock) && "Not an exiting block!"
) ? static_cast<void> (0) : __assert_fail ("!L->contains(ExitingBlock) && \"Not an exiting block!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 7111, __PRETTY_FUNCTION__))
;
7112
7113 // Give up if the exit is the default dest of a switch.
7114 if (Switch->getDefaultDest() == ExitingBlock)
7115 return getCouldNotCompute();
7116
7117 assert(L->contains(Switch->getDefaultDest()) &&((L->contains(Switch->getDefaultDest()) && "Default case must not exit the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 7118, __PRETTY_FUNCTION__))
7118 "Default case must not exit the loop!")((L->contains(Switch->getDefaultDest()) && "Default case must not exit the loop!"
) ? static_cast<void> (0) : __assert_fail ("L->contains(Switch->getDefaultDest()) && \"Default case must not exit the loop!\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 7118, __PRETTY_FUNCTION__))
;
7119 const SCEV *LHS = getSCEVAtScope(Switch->getCondition(), L);
7120 const SCEV *RHS = getConstant(Switch->findCaseDest(ExitingBlock));
7121
7122 // while (X != Y) --> while (X-Y != 0)
7123 ExitLimit EL = howFarToZero(getMinusSCEV(LHS, RHS), L, ControlsExit);
7124 if (EL.hasAnyInfo())
7125 return EL;
7126
7127 return getCouldNotCompute();
7128}
7129
7130static ConstantInt *
7131EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
7132 ScalarEvolution &SE) {
7133 const SCEV *InVal = SE.getConstant(C);
7134 const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE);
7135 assert(isa<SCEVConstant>(Val) &&((isa<SCEVConstant>(Val) && "Evaluation of SCEV at constant didn't fold correctly?"
) ? static_cast<void> (0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 7136, __PRETTY_FUNCTION__))
7136 "Evaluation of SCEV at constant didn't fold correctly?")((isa<SCEVConstant>(Val) && "Evaluation of SCEV at constant didn't fold correctly?"
) ? static_cast<void> (0) : __assert_fail ("isa<SCEVConstant>(Val) && \"Evaluation of SCEV at constant didn't fold correctly?\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 7136, __PRETTY_FUNCTION__))
;
7137 return cast<SCEVConstant>(Val)->getValue();
7138}
7139
7140/// Given an exit condition of 'icmp op load X, cst', try to see if we can
7141/// compute the backedge execution count.
7142ScalarEvolution::ExitLimit
7143ScalarEvolution::computeLoadConstantCompareExitLimit(
7144 LoadInst *LI,
7145 Constant *RHS,
7146 const Loop *L,
7147 ICmpInst::Predicate predicate) {
7148 if (LI->isVolatile()) return getCouldNotCompute();
7149
7150 // Check to see if the loaded pointer is a getelementptr of a global.
7151 // TODO: Use SCEV instead of manually grubbing with GEPs.
7152 GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0));
7153 if (!GEP) return getCouldNotCompute();
7154
7155 // Make sure that it is really a constant global we are gepping, with an
7156 // initializer, and make sure the first IDX is really 0.
7157 GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
7158 if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
7159 GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) ||
7160 !cast<Constant>(GEP->getOperand(1))->isNullValue())
7161 return getCouldNotCompute();
7162
7163 // Okay, we allow one non-constant index into the GEP instruction.
7164 Value *VarIdx = nullptr;
7165 std::vector<Constant*> Indexes;
7166 unsigned VarIdxNum = 0;
7167 for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i)
7168 if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
7169 Indexes.push_back(CI);
7170 } else if (!isa<ConstantInt>(GEP->getOperand(i))) {
7171 if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's.
7172 VarIdx = GEP->getOperand(i);
7173 VarIdxNum = i-2;
7174 Indexes.push_back(nullptr);
7175 }
7176
7177 // Loop-invariant loads may be a byproduct of loop optimization. Skip them.
7178 if (!VarIdx)
7179 return getCouldNotCompute();
7180
7181 // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant.
7182 // Check to see if X is a loop variant variable value now.
7183 const SCEV *Idx = getSCEV(VarIdx);
7184 Idx = getSCEVAtScope(Idx, L);
7185
7186 // We can only recognize very limited forms of loop index expressions, in
7187 // particular, only affine AddRec's like {C1,+,C2}.
7188 const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
7189 if (!IdxExpr || !IdxExpr->isAffine() || isLoopInvariant(IdxExpr, L) ||
7190 !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
7191 !isa<SCEVConstant>(IdxExpr->getOperand(1)))
7192 return getCouldNotCompute();
7193
7194 unsigned MaxSteps = MaxBruteForceIterations;
7195 for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) {
7196 ConstantInt *ItCst = ConstantInt::get(
7197 cast<IntegerType>(IdxExpr->getType()), IterationNum);
7198 ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this);
7199
7200 // Form the GEP offset.
7201 Indexes[VarIdxNum] = Val;
7202
7203 Constant *Result = ConstantFoldLoadThroughGEPIndices(GV->getInitializer(),
7204 Indexes);
7205 if (!Result) break; // Cannot compute!
7206
7207 // Evaluate the condition for this iteration.
7208 Result = ConstantExpr::getICmp(predicate, Result, RHS);
7209 if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure
7210 if (cast<ConstantInt>(Result)->getValue().isMinValue()) {
7211 ++NumArrayLenItCounts;
7212 return getConstant(ItCst); // Found terminating iteration!
7213 }
7214 }
7215 return getCouldNotCompute();
7216}
7217
7218ScalarEvolution::ExitLimit ScalarEvolution::computeShiftCompareExitLimit(
7219 Value *LHS, Value *RHSV, const Loop *L, ICmpInst::Predicate Pred) {
7220 ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV);
7221 if (!RHS)
7222 return getCouldNotCompute();
7223
7224 const BasicBlock *Latch = L->getLoopLatch();
7225 if (!Latch)
7226 return getCouldNotCompute();
7227
7228 const BasicBlock *Predecessor = L->getLoopPredecessor();
7229 if (!Predecessor)
7230 return getCouldNotCompute();
7231
7232 // Return true if V is of the form "LHS `shift_op` <positive constant>".
7233 // Return LHS in OutLHS and shift_opt in OutOpCode.
7234 auto MatchPositiveShift =
7235 [](Value *V, Value *&OutLHS, Instruction::BinaryOps &OutOpCode) {
7236
7237 using namespace PatternMatch;
7238
7239 ConstantInt *ShiftAmt;
7240 if (match(V, m_LShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7241 OutOpCode = Instruction::LShr;
7242 else if (match(V, m_AShr(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7243 OutOpCode = Instruction::AShr;
7244 else if (match(V, m_Shl(m_Value(OutLHS), m_ConstantInt(ShiftAmt))))
7245 OutOpCode = Instruction::Shl;
7246 else
7247 return false;
7248
7249 return ShiftAmt->getValue().isStrictlyPositive();
7250 };
7251
7252 // Recognize a "shift recurrence" either of the form %iv or of %iv.shifted in
7253 //
7254 // loop:
7255 // %iv = phi i32 [ %iv.shifted, %loop ], [ %val, %preheader ]
7256 // %iv.shifted = lshr i32 %iv, <positive constant>
7257 //
7258 // Return true on a successful match. Return the corresponding PHI node (%iv
7259 // above) in PNOut and the opcode of the shift operation in OpCodeOut.
7260 auto MatchShiftRecurrence =
7261 [&](Value *V, PHINode *&PNOut, Instruction::BinaryOps &OpCodeOut) {
7262 Optional<Instruction::BinaryOps> PostShiftOpCode;
7263
7264 {
7265 Instruction::BinaryOps OpC;
7266 Value *V;
7267
7268 // If we encounter a shift instruction, "peel off" the shift operation,
7269 // and remember that we did so. Later when we inspect %iv's backedge
7270 // value, we will make sure that the backedge value uses the same
7271 // operation.
7272 //
7273 // Note: the peeled shift operation does not have to be the same
7274 // instruction as the one feeding into the PHI's backedge value. We only
7275 // really care about it being the same *kind* of shift instruction --
7276 // that's all that is required for our later inferences to hold.
7277 if (MatchPositiveShift(LHS, V, OpC)) {
7278 PostShiftOpCode = OpC;
7279 LHS = V;
7280 }
7281 }
7282
7283 PNOut = dyn_cast<PHINode>(LHS);
7284 if (!PNOut || PNOut->getParent() != L->getHeader())
7285 return false;
7286
7287 Value *BEValue = PNOut->getIncomingValueForBlock(Latch);
7288 Value *OpLHS;
7289
7290 return
7291 // The backedge value for the PHI node must be a shift by a positive
7292 // amount
7293 MatchPositiveShift(BEValue, OpLHS, OpCodeOut) &&
7294
7295 // of the PHI node itself
7296 OpLHS == PNOut &&
7297
7298 // and the kind of shift should be match the kind of shift we peeled
7299 // off, if any.
7300 (!PostShiftOpCode.hasValue() || *PostShiftOpCode == OpCodeOut);
7301 };
7302
7303 PHINode *PN;
7304 Instruction::BinaryOps OpCode;
7305 if (!MatchShiftRecurrence(LHS, PN, OpCode))
7306 return getCouldNotCompute();
7307
7308 const DataLayout &DL = getDataLayout();
7309
7310 // The key rationale for this optimization is that for some kinds of shift
7311 // recurrences, the value of the recurrence "stabilizes" to either 0 or -1
7312 // within a finite number of iterations. If the condition guarding the
7313 // backedge (in the sense that the backedge is taken if the condition is true)
7314 // is false for the value the shift recurrence stabilizes to, then we know
7315 // that the backedge is taken only a finite number of times.
7316
7317 ConstantInt *StableValue = nullptr;
7318 switch (OpCode) {
7319 default:
7320 llvm_unreachable("Impossible case!")::llvm::llvm_unreachable_internal("Impossible case!", "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 7320)
;
7321
7322 case Instruction::AShr: {
7323 // {K,ashr,<positive-constant>} stabilizes to signum(K) in at most
7324 // bitwidth(K) iterations.
7325 Value *FirstValue = PN->getIncomingValueForBlock(Predecessor);
7326 KnownBits Known = computeKnownBits(FirstValue, DL, 0, nullptr,
7327 Predecessor->getTerminator(), &DT);
7328 auto *Ty = cast<IntegerType>(RHS->getType());
7329 if (Known.isNonNegative())
7330 StableValue = ConstantInt::get(Ty, 0);
7331 else if (Known.isNegative())
7332 StableValue = ConstantInt::get(Ty, -1, true);
7333 else
7334 return getCouldNotCompute();
7335
7336 break;
7337 }
7338 case Instruction::LShr:
7339 case Instruction::Shl:
7340 // Both {K,lshr,<positive-constant>} and {K,shl,<positive-constant>}
7341 // stabilize to 0 in at most bitwidth(K) iterations.
7342 StableValue = ConstantInt::get(cast<IntegerType>(RHS->getType()), 0);
7343 break;
7344 }
7345
7346 auto *Result =
7347 ConstantFoldCompareInstOperands(Pred, StableValue, RHS, DL, &TLI);
7348 assert(Result->getType()->isIntegerTy(1) &&((Result->getType()->isIntegerTy(1) && "Otherwise cannot be an operand to a branch instruction"
) ? static_cast<void> (0) : __assert_fail ("Result->getType()->isIntegerTy(1) && \"Otherwise cannot be an operand to a branch instruction\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 7349, __PRETTY_FUNCTION__))
7349 "Otherwise cannot be an operand to a branch instruction")((Result->getType()->isIntegerTy(1) && "Otherwise cannot be an operand to a branch instruction"
) ? static_cast<void> (0) : __assert_fail ("Result->getType()->isIntegerTy(1) && \"Otherwise cannot be an operand to a branch instruction\""
, "/build/llvm-toolchain-snapshot-6.0~svn316068/lib/Analysis/ScalarEvolution.cpp"
, 7349, __PRETTY_FUNCTION__))
;
7350
7351 if (Result->isZeroValue()) {
7352 unsigned BitWidth = getTypeSizeInBits(RHS->getType());
7353 const SCEV *UpperBound =
7354 getConstant(getEffectiveSCEVType(RHS->getType()), BitWidth);
7355 return ExitLimit(getCouldNotCompute(), UpperBound, false);
7356 }