Bug Summary

File:lib/Analysis/ScalarEvolution.cpp
Warning:line 7919, column 23
Value stored to 'MultipleInitValues' is never read

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name ScalarEvolution.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-eagerly-assume -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-7/lib/clang/7.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-7~svn329677/build-llvm/lib/Analysis -I /build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis -I /build/llvm-toolchain-snapshot-7~svn329677/build-llvm/include -I /build/llvm-toolchain-snapshot-7~svn329677/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/x86_64-linux-gnu/c++/7.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/x86_64-linux-gnu/c++/7.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/backward -internal-isystem /usr/include/clang/7.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-7/lib/clang/7.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-7~svn329677/build-llvm/lib/Analysis -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-checker optin.performance.Padding -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-04-11-031539-24776-1 -x c++ /build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp
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/EquivalenceClasses.h"
67#include "llvm/ADT/FoldingSet.h"
68#include "llvm/ADT/None.h"
69#include "llvm/ADT/Optional.h"
70#include "llvm/ADT/STLExtras.h"
71#include "llvm/ADT/ScopeExit.h"
72#include "llvm/ADT/Sequence.h"
73#include "llvm/ADT/SetVector.h"
74#include "llvm/ADT/SmallPtrSet.h"
75#include "llvm/ADT/SmallSet.h"
76#include "llvm/ADT/SmallVector.h"
77#include "llvm/ADT/Statistic.h"
78#include "llvm/ADT/StringRef.h"
79#include "llvm/Analysis/AssumptionCache.h"
80#include "llvm/Analysis/ConstantFolding.h"
81#include "llvm/Analysis/InstructionSimplify.h"
82#include "llvm/Analysis/LoopInfo.h"
83#include "llvm/Analysis/ScalarEvolutionExpressions.h"
84#include "llvm/Analysis/TargetLibraryInfo.h"
85#include "llvm/Analysis/ValueTracking.h"
86#include "llvm/IR/Argument.h"
87#include "llvm/IR/BasicBlock.h"
88#include "llvm/IR/CFG.h"
89#include "llvm/IR/CallSite.h"
90#include "llvm/IR/Constant.h"
91#include "llvm/IR/ConstantRange.h"
92#include "llvm/IR/Constants.h"
93#include "llvm/IR/DataLayout.h"
94#include "llvm/IR/DerivedTypes.h"
95#include "llvm/IR/Dominators.h"
96#include "llvm/IR/Function.h"
97#include "llvm/IR/GlobalAlias.h"
98#include "llvm/IR/GlobalValue.h"
99#include "llvm/IR/GlobalVariable.h"
100#include "llvm/IR/InstIterator.h"
101#include "llvm/IR/InstrTypes.h"
102#include "llvm/IR/Instruction.h"
103#include "llvm/IR/Instructions.h"
104#include "llvm/IR/IntrinsicInst.h"
105#include "llvm/IR/Intrinsics.h"
106#include "llvm/IR/LLVMContext.h"
107#include "llvm/IR/Metadata.h"
108#include "llvm/IR/Operator.h"
109#include "llvm/IR/PatternMatch.h"
110#include "llvm/IR/Type.h"
111#include "llvm/IR/Use.h"
112#include "llvm/IR/User.h"
113#include "llvm/IR/Value.h"
114#include "llvm/Pass.h"
115#include "llvm/Support/Casting.h"
116#include "llvm/Support/CommandLine.h"
117#include "llvm/Support/Compiler.h"
118#include "llvm/Support/Debug.h"
119#include "llvm/Support/ErrorHandling.h"
120#include "llvm/Support/KnownBits.h"
121#include "llvm/Support/SaveAndRestore.h"
122#include "llvm/Support/raw_ostream.h"
123#include <algorithm>
124#include <cassert>
125#include <climits>
126#include <cstddef>
127#include <cstdint>
128#include <cstdlib>
129#include <map>
130#include <memory>
131#include <tuple>
132#include <utility>
133#include <vector>
134
135using namespace llvm;
136
137#define DEBUG_TYPE"scalar-evolution" "scalar-evolution"
138
139STATISTIC(NumArrayLenItCounts,static llvm::Statistic NumArrayLenItCounts = {"scalar-evolution"
, "NumArrayLenItCounts", "Number of trip counts computed with array length"
, {0}, {false}}
140 "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}}
;
141STATISTIC(NumTripCountsComputed,static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
, {0}, {false}}
142 "Number of loops with predictable loop counts")static llvm::Statistic NumTripCountsComputed = {"scalar-evolution"
, "NumTripCountsComputed", "Number of loops with predictable loop counts"
, {0}, {false}}
;
143STATISTIC(NumTripCountsNotComputed,static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
, {0}, {false}}
144 "Number of loops without predictable loop counts")static llvm::Statistic NumTripCountsNotComputed = {"scalar-evolution"
, "NumTripCountsNotComputed", "Number of loops without predictable loop counts"
, {0}, {false}}
;
145STATISTIC(NumBruteForceTripCountsComputed,static llvm::Statistic NumBruteForceTripCountsComputed = {"scalar-evolution"
, "NumBruteForceTripCountsComputed", "Number of loops with trip counts computed by force"
, {0}, {false}}
146 "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}}
;
147
148static cl::opt<unsigned>
149MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
150 cl::desc("Maximum number of iterations SCEV will "
151 "symbolically execute a constant "
152 "derived loop"),
153 cl::init(100));
154
155// FIXME: Enable this with EXPENSIVE_CHECKS when the test suite is clean.
156static cl::opt<bool> VerifySCEV(
157 "verify-scev", cl::Hidden,
158 cl::desc("Verify ScalarEvolution's backedge taken counts (slow)"));
159static cl::opt<bool>
160 VerifySCEVMap("verify-scev-maps", cl::Hidden,
161 cl::desc("Verify no dangling value in ScalarEvolution's "
162 "ExprValueMap (slow)"));
163
164static cl::opt<unsigned> MulOpsInlineThreshold(
165 "scev-mulops-inline-threshold", cl::Hidden,
166 cl::desc("Threshold for inlining multiplication operands into a SCEV"),
167 cl::init(32));
168
169static cl::opt<unsigned> AddOpsInlineThreshold(
170 "scev-addops-inline-threshold", cl::Hidden,
171 cl::desc("Threshold for inlining addition operands into a SCEV"),
172 cl::init(500));
173
174static cl::opt<unsigned> MaxSCEVCompareDepth(
175 "scalar-evolution-max-scev-compare-depth", cl::Hidden,
176 cl::desc("Maximum depth of recursive SCEV complexity comparisons"),
177 cl::init(32));
178
179static cl::opt<unsigned> MaxSCEVOperationsImplicationDepth(
180 "scalar-evolution-max-scev-operations-implication-depth", cl::Hidden,
181 cl::desc("Maximum depth of recursive SCEV operations implication analysis"),
182 cl::init(2));
183
184static cl::opt<unsigned> MaxValueCompareDepth(
185 "scalar-evolution-max-value-compare-depth", cl::Hidden,
186 cl::desc("Maximum depth of recursive value complexity comparisons"),
187 cl::init(2));
188
189static cl::opt<unsigned>
190 MaxArithDepth("scalar-evolution-max-arith-depth", cl::Hidden,
191 cl::desc("Maximum depth of recursive arithmetics"),
192 cl::init(32));
193
194static cl::opt<unsigned> MaxConstantEvolvingDepth(
195 "scalar-evolution-max-constant-evolving-depth", cl::Hidden,
196 cl::desc("Maximum depth of recursive constant evolving"), cl::init(32));
197
198static cl::opt<unsigned>
199 MaxExtDepth("scalar-evolution-max-ext-depth", cl::Hidden,
200 cl::desc("Maximum depth of recursive SExt/ZExt"),
201 cl::init(8));
202
203static cl::opt<unsigned>
204 MaxAddRecSize("scalar-evolution-max-add-rec-size", cl::Hidden,
205 cl::desc("Max coefficients in AddRec during evolving"),
206 cl::init(16));
207
208//===----------------------------------------------------------------------===//
209// SCEV class definitions
210//===----------------------------------------------------------------------===//
211
212//===----------------------------------------------------------------------===//
213// Implementation of the SCEV class.
214//
215
216#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
217LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void SCEV::dump() const {
218 print(dbgs());
219 dbgs() << '\n';
220}
221#endif
222
223void SCEV::print(raw_ostream &OS) const {
224 switch (static_cast<SCEVTypes>(getSCEVType())) {
225 case scConstant:
226 cast<SCEVConstant>(this)->getValue()->printAsOperand(OS, false);
227 return;
228 case scTruncate: {
229 const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(this);
230 const SCEV *Op = Trunc->getOperand();
231 OS << "(trunc " << *Op->getType() << " " << *Op << " to "
232 << *Trunc->getType() << ")";
233 return;
234 }
235 case scZeroExtend: {
236 const SCEVZeroExtendExpr *ZExt = cast<SCEVZeroExtendExpr>(this);
237 const SCEV *Op = ZExt->getOperand();
238 OS << "(zext " << *Op->getType() << " " << *Op << " to "
239 << *ZExt->getType() << ")";
240 return;
241 }
242 case scSignExtend: {
243 const SCEVSignExtendExpr *SExt = cast<SCEVSignExtendExpr>(this);
244 const SCEV *Op = SExt->getOperand();
245 OS << "(sext " << *Op->getType() << " " << *Op << " to "
246 << *SExt->getType() << ")";
247 return;
248 }
249 case scAddRecExpr: {
250 const SCEVAddRecExpr *AR = cast<SCEVAddRecExpr>(this);
251 OS << "{" << *AR->getOperand(0);
252 for (unsigned i = 1, e = AR->getNumOperands(); i != e; ++i)
253 OS << ",+," << *AR->getOperand(i);
254 OS << "}<";
255 if (AR->hasNoUnsignedWrap())
256 OS << "nuw><";
257 if (AR->hasNoSignedWrap())
258 OS << "nsw><";
259 if (AR->hasNoSelfWrap() &&
260 !AR->getNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW)))
261 OS << "nw><";
262 AR->getLoop()->getHeader()->printAsOperand(OS, /*PrintType=*/false);
263 OS << ">";
264 return;
265 }
266 case scAddExpr:
267 case scMulExpr:
268 case scUMaxExpr:
269 case scSMaxExpr: {
270 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(this);
271 const char *OpStr = nullptr;
272 switch (NAry->getSCEVType()) {
273 case scAddExpr: OpStr = " + "; break;
274 case scMulExpr: OpStr = " * "; break;
275 case scUMaxExpr: OpStr = " umax "; break;
276 case scSMaxExpr: OpStr = " smax "; break;
277 }
278 OS << "(";
279 for (SCEVNAryExpr::op_iterator I = NAry->op_begin(), E = NAry->op_end();
280 I != E; ++I) {
281 OS << **I;
282 if (std::next(I) != E)
283 OS << OpStr;
284 }
285 OS << ")";
286 switch (NAry->getSCEVType()) {
287 case scAddExpr:
288 case scMulExpr:
289 if (NAry->hasNoUnsignedWrap())
290 OS << "<nuw>";
291 if (NAry->hasNoSignedWrap())
292 OS << "<nsw>";
293 }
294 return;
295 }
296 case scUDivExpr: {
297 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(this);
298 OS << "(" << *UDiv->getLHS() << " /u " << *UDiv->getRHS() << ")";
299 return;
300 }
301 case scUnknown: {
302 const SCEVUnknown *U = cast<SCEVUnknown>(this);
303 Type *AllocTy;
304 if (U->isSizeOf(AllocTy)) {
305 OS << "sizeof(" << *AllocTy << ")";
306 return;
307 }
308 if (U->isAlignOf(AllocTy)) {
309 OS << "alignof(" << *AllocTy << ")";
310 return;
311 }
312
313 Type *CTy;
314 Constant *FieldNo;
315 if (U->isOffsetOf(CTy, FieldNo)) {
316 OS << "offsetof(" << *CTy << ", ";
317 FieldNo->printAsOperand(OS, false);
318 OS << ")";
319 return;
320 }
321
322 // Otherwise just print it normally.
323 U->getValue()->printAsOperand(OS, false);
324 return;
325 }
326 case scCouldNotCompute:
327 OS << "***COULDNOTCOMPUTE***";
328 return;
329 }
330 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 330)
;
331}
332
333Type *SCEV::getType() const {
334 switch (static_cast<SCEVTypes>(getSCEVType())) {
335 case scConstant:
336 return cast<SCEVConstant>(this)->getType();
337 case scTruncate:
338 case scZeroExtend:
339 case scSignExtend:
340 return cast<SCEVCastExpr>(this)->getType();
341 case scAddRecExpr:
342 case scMulExpr:
343 case scUMaxExpr:
344 case scSMaxExpr:
345 return cast<SCEVNAryExpr>(this)->getType();
346 case scAddExpr:
347 return cast<SCEVAddExpr>(this)->getType();
348 case scUDivExpr:
349 return cast<SCEVUDivExpr>(this)->getType();
350 case scUnknown:
351 return cast<SCEVUnknown>(this)->getType();
352 case scCouldNotCompute:
353 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 353)
;
354 }
355 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 355)
;
356}
357
358bool SCEV::isZero() const {
359 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
360 return SC->getValue()->isZero();
361 return false;
362}
363
364bool SCEV::isOne() const {
365 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
366 return SC->getValue()->isOne();
367 return false;
368}
369
370bool SCEV::isAllOnesValue() const {
371 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
372 return SC->getValue()->isMinusOne();
373 return false;
374}
375
376bool SCEV::isNonConstantNegative() const {
377 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(this);
378 if (!Mul) return false;
379
380 // If there is a constant factor, it will be first.
381 const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
382 if (!SC) return false;
383
384 // Return true if the value is negative, this matches things like (-42 * V).
385 return SC->getAPInt().isNegative();
386}
387
388SCEVCouldNotCompute::SCEVCouldNotCompute() :
389 SCEV(FoldingSetNodeIDRef(), scCouldNotCompute) {}
390
391bool SCEVCouldNotCompute::classof(const SCEV *S) {
392 return S->getSCEVType() == scCouldNotCompute;
393}
394
395const SCEV *ScalarEvolution::getConstant(ConstantInt *V) {
396 FoldingSetNodeID ID;
397 ID.AddInteger(scConstant);
398 ID.AddPointer(V);
399 void *IP = nullptr;
400 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
401 SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V);
402 UniqueSCEVs.InsertNode(S, IP);
403 return S;
404}
405
406const SCEV *ScalarEvolution::getConstant(const APInt &Val) {
407 return getConstant(ConstantInt::get(getContext(), Val));
408}
409
410const SCEV *
411ScalarEvolution::getConstant(Type *Ty, uint64_t V, bool isSigned) {
412 IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
413 return getConstant(ConstantInt::get(ITy, V, isSigned));
414}
415
416SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID,
417 unsigned SCEVTy, const SCEV *op, Type *ty)
418 : SCEV(ID, SCEVTy), Op(op), Ty(ty) {}
419
420SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
421 const SCEV *op, Type *ty)
422 : SCEVCastExpr(ID, scTruncate, op, ty) {
423 assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(static_cast <bool> ((Op->getType()->isIntegerTy(
) || Op->getType()->isPointerTy()) && (Ty->isIntegerTy
() || Ty->isPointerTy()) && "Cannot truncate non-integer value!"
) ? void (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 425, __extension__ __PRETTY_FUNCTION__))
424 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(static_cast <bool> ((Op->getType()->isIntegerTy(
) || Op->getType()->isPointerTy()) && (Ty->isIntegerTy
() || Ty->isPointerTy()) && "Cannot truncate non-integer value!"
) ? void (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 425, __extension__ __PRETTY_FUNCTION__))
425 "Cannot truncate non-integer value!")(static_cast <bool> ((Op->getType()->isIntegerTy(
) || Op->getType()->isPointerTy()) && (Ty->isIntegerTy
() || Ty->isPointerTy()) && "Cannot truncate non-integer value!"
) ? void (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate non-integer value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 425, __extension__ __PRETTY_FUNCTION__))
;
426}
427
428SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
429 const SCEV *op, Type *ty)
430 : SCEVCastExpr(ID, scZeroExtend, op, ty) {
431 assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(static_cast <bool> ((Op->getType()->isIntegerTy(
) || Op->getType()->isPointerTy()) && (Ty->isIntegerTy
() || Ty->isPointerTy()) && "Cannot zero extend non-integer value!"
) ? void (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 433, __extension__ __PRETTY_FUNCTION__))
432 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(static_cast <bool> ((Op->getType()->isIntegerTy(
) || Op->getType()->isPointerTy()) && (Ty->isIntegerTy
() || Ty->isPointerTy()) && "Cannot zero extend non-integer value!"
) ? void (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 433, __extension__ __PRETTY_FUNCTION__))
433 "Cannot zero extend non-integer value!")(static_cast <bool> ((Op->getType()->isIntegerTy(
) || Op->getType()->isPointerTy()) && (Ty->isIntegerTy
() || Ty->isPointerTy()) && "Cannot zero extend non-integer value!"
) ? void (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot zero extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 433, __extension__ __PRETTY_FUNCTION__))
;
434}
435
436SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
437 const SCEV *op, Type *ty)
438 : SCEVCastExpr(ID, scSignExtend, op, ty) {
439 assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&(static_cast <bool> ((Op->getType()->isIntegerTy(
) || Op->getType()->isPointerTy()) && (Ty->isIntegerTy
() || Ty->isPointerTy()) && "Cannot sign extend non-integer value!"
) ? void (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 441, __extension__ __PRETTY_FUNCTION__))
440 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(static_cast <bool> ((Op->getType()->isIntegerTy(
) || Op->getType()->isPointerTy()) && (Ty->isIntegerTy
() || Ty->isPointerTy()) && "Cannot sign extend non-integer value!"
) ? void (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 441, __extension__ __PRETTY_FUNCTION__))
441 "Cannot sign extend non-integer value!")(static_cast <bool> ((Op->getType()->isIntegerTy(
) || Op->getType()->isPointerTy()) && (Ty->isIntegerTy
() || Ty->isPointerTy()) && "Cannot sign extend non-integer value!"
) ? void (0) : __assert_fail ("(Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot sign extend non-integer value!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 441, __extension__ __PRETTY_FUNCTION__))
;
442}
443
444void SCEVUnknown::deleted() {
445 // Clear this SCEVUnknown from various maps.
446 SE->forgetMemoizedResults(this);
447
448 // Remove this SCEVUnknown from the uniquing map.
449 SE->UniqueSCEVs.RemoveNode(this);
450
451 // Release the value.
452 setValPtr(nullptr);
453}
454
455void SCEVUnknown::allUsesReplacedWith(Value *New) {
456 // Remove this SCEVUnknown from the uniquing map.
457 SE->UniqueSCEVs.RemoveNode(this);
458
459 // Update this SCEVUnknown to point to the new value. This is needed
460 // because there may still be outstanding SCEVs which still point to
461 // this SCEVUnknown.
462 setValPtr(New);
463}
464
465bool SCEVUnknown::isSizeOf(Type *&AllocTy) const {
466 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
467 if (VCE->getOpcode() == Instruction::PtrToInt)
468 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
469 if (CE->getOpcode() == Instruction::GetElementPtr &&
470 CE->getOperand(0)->isNullValue() &&
471 CE->getNumOperands() == 2)
472 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1)))
473 if (CI->isOne()) {
474 AllocTy = cast<PointerType>(CE->getOperand(0)->getType())
475 ->getElementType();
476 return true;
477 }
478
479 return false;
480}
481
482bool SCEVUnknown::isAlignOf(Type *&AllocTy) const {
483 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
484 if (VCE->getOpcode() == Instruction::PtrToInt)
485 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
486 if (CE->getOpcode() == Instruction::GetElementPtr &&
487 CE->getOperand(0)->isNullValue()) {
488 Type *Ty =
489 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
490 if (StructType *STy = dyn_cast<StructType>(Ty))
491 if (!STy->isPacked() &&
492 CE->getNumOperands() == 3 &&
493 CE->getOperand(1)->isNullValue()) {
494 if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2)))
495 if (CI->isOne() &&
496 STy->getNumElements() == 2 &&
497 STy->getElementType(0)->isIntegerTy(1)) {
498 AllocTy = STy->getElementType(1);
499 return true;
500 }
501 }
502 }
503
504 return false;
505}
506
507bool SCEVUnknown::isOffsetOf(Type *&CTy, Constant *&FieldNo) const {
508 if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(getValue()))
509 if (VCE->getOpcode() == Instruction::PtrToInt)
510 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
511 if (CE->getOpcode() == Instruction::GetElementPtr &&
512 CE->getNumOperands() == 3 &&
513 CE->getOperand(0)->isNullValue() &&
514 CE->getOperand(1)->isNullValue()) {
515 Type *Ty =
516 cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
517 // Ignore vector types here so that ScalarEvolutionExpander doesn't
518 // emit getelementptrs that index into vectors.
519 if (Ty->isStructTy() || Ty->isArrayTy()) {
520 CTy = Ty;
521 FieldNo = CE->getOperand(2);
522 return true;
523 }
524 }
525
526 return false;
527}
528
529//===----------------------------------------------------------------------===//
530// SCEV Utilities
531//===----------------------------------------------------------------------===//
532
533/// Compare the two values \p LV and \p RV in terms of their "complexity" where
534/// "complexity" is a partial (and somewhat ad-hoc) relation used to order
535/// operands in SCEV expressions. \p EqCache is a set of pairs of values that
536/// have been previously deemed to be "equally complex" by this routine. It is
537/// intended to avoid exponential time complexity in cases like:
538///
539/// %a = f(%x, %y)
540/// %b = f(%a, %a)
541/// %c = f(%b, %b)
542///
543/// %d = f(%x, %y)
544/// %e = f(%d, %d)
545/// %f = f(%e, %e)
546///
547/// CompareValueComplexity(%f, %c)
548///
549/// Since we do not continue running this routine on expression trees once we
550/// have seen unequal values, there is no need to track them in the cache.
551static int
552CompareValueComplexity(EquivalenceClasses<const Value *> &EqCacheValue,
553 const LoopInfo *const LI, Value *LV, Value *RV,
554 unsigned Depth) {
555 if (Depth > MaxValueCompareDepth || EqCacheValue.isEquivalent(LV, RV))
556 return 0;
557
558 // Order pointer values after integer values. This helps SCEVExpander form
559 // GEPs.
560 bool LIsPointer = LV->getType()->isPointerTy(),
561 RIsPointer = RV->getType()->isPointerTy();
562 if (LIsPointer != RIsPointer)
563 return (int)LIsPointer - (int)RIsPointer;
564
565 // Compare getValueID values.
566 unsigned LID = LV->getValueID(), RID = RV->getValueID();
567 if (LID != RID)
568 return (int)LID - (int)RID;
569
570 // Sort arguments by their position.
571 if (const auto *LA = dyn_cast<Argument>(LV)) {
572 const auto *RA = cast<Argument>(RV);
573 unsigned LArgNo = LA->getArgNo(), RArgNo = RA->getArgNo();
574 return (int)LArgNo - (int)RArgNo;
575 }
576
577 if (const auto *LGV = dyn_cast<GlobalValue>(LV)) {
578 const auto *RGV = cast<GlobalValue>(RV);
579
580 const auto IsGVNameSemantic = [&](const GlobalValue *GV) {
581 auto LT = GV->getLinkage();
582 return !(GlobalValue::isPrivateLinkage(LT) ||
583 GlobalValue::isInternalLinkage(LT));
584 };
585
586 // Use the names to distinguish the two values, but only if the
587 // names are semantically important.
588 if (IsGVNameSemantic(LGV) && IsGVNameSemantic(RGV))
589 return LGV->getName().compare(RGV->getName());
590 }
591
592 // For instructions, compare their loop depth, and their operand count. This
593 // is pretty loose.
594 if (const auto *LInst = dyn_cast<Instruction>(LV)) {
595 const auto *RInst = cast<Instruction>(RV);
596
597 // Compare loop depths.
598 const BasicBlock *LParent = LInst->getParent(),
599 *RParent = RInst->getParent();
600 if (LParent != RParent) {
601 unsigned LDepth = LI->getLoopDepth(LParent),
602 RDepth = LI->getLoopDepth(RParent);
603 if (LDepth != RDepth)
604 return (int)LDepth - (int)RDepth;
605 }
606
607 // Compare the number of operands.
608 unsigned LNumOps = LInst->getNumOperands(),
609 RNumOps = RInst->getNumOperands();
610 if (LNumOps != RNumOps)
611 return (int)LNumOps - (int)RNumOps;
612
613 for (unsigned Idx : seq(0u, LNumOps)) {
614 int Result =
615 CompareValueComplexity(EqCacheValue, LI, LInst->getOperand(Idx),
616 RInst->getOperand(Idx), Depth + 1);
617 if (Result != 0)
618 return Result;
619 }
620 }
621
622 EqCacheValue.unionSets(LV, RV);
623 return 0;
624}
625
626// Return negative, zero, or positive, if LHS is less than, equal to, or greater
627// than RHS, respectively. A three-way result allows recursive comparisons to be
628// more efficient.
629static int CompareSCEVComplexity(
630 EquivalenceClasses<const SCEV *> &EqCacheSCEV,
631 EquivalenceClasses<const Value *> &EqCacheValue,
632 const LoopInfo *const LI, const SCEV *LHS, const SCEV *RHS,
633 DominatorTree &DT, unsigned Depth = 0) {
634 // Fast-path: SCEVs are uniqued so we can do a quick equality check.
635 if (LHS == RHS)
636 return 0;
637
638 // Primarily, sort the SCEVs by their getSCEVType().
639 unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
640 if (LType != RType)
641 return (int)LType - (int)RType;
642
643 if (Depth > MaxSCEVCompareDepth || EqCacheSCEV.isEquivalent(LHS, RHS))
644 return 0;
645 // Aside from the getSCEVType() ordering, the particular ordering
646 // isn't very important except that it's beneficial to be consistent,
647 // so that (a + b) and (b + a) don't end up as different expressions.
648 switch (static_cast<SCEVTypes>(LType)) {
649 case scUnknown: {
650 const SCEVUnknown *LU = cast<SCEVUnknown>(LHS);
651 const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
652
653 int X = CompareValueComplexity(EqCacheValue, LI, LU->getValue(),
654 RU->getValue(), Depth + 1);
655 if (X == 0)
656 EqCacheSCEV.unionSets(LHS, RHS);
657 return X;
658 }
659
660 case scConstant: {
661 const SCEVConstant *LC = cast<SCEVConstant>(LHS);
662 const SCEVConstant *RC = cast<SCEVConstant>(RHS);
663
664 // Compare constant values.
665 const APInt &LA = LC->getAPInt();
666 const APInt &RA = RC->getAPInt();
667 unsigned LBitWidth = LA.getBitWidth(), RBitWidth = RA.getBitWidth();
668 if (LBitWidth != RBitWidth)
669 return (int)LBitWidth - (int)RBitWidth;
670 return LA.ult(RA) ? -1 : 1;
671 }
672
673 case scAddRecExpr: {
674 const SCEVAddRecExpr *LA = cast<SCEVAddRecExpr>(LHS);
675 const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
676
677 // There is always a dominance between two recs that are used by one SCEV,
678 // so we can safely sort recs by loop header dominance. We require such
679 // order in getAddExpr.
680 const Loop *LLoop = LA->getLoop(), *RLoop = RA->getLoop();
681 if (LLoop != RLoop) {
682 const BasicBlock *LHead = LLoop->getHeader(), *RHead = RLoop->getHeader();
683 assert(LHead != RHead && "Two loops share the same header?")(static_cast <bool> (LHead != RHead && "Two loops share the same header?"
) ? void (0) : __assert_fail ("LHead != RHead && \"Two loops share the same header?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 683, __extension__ __PRETTY_FUNCTION__))
;
684 if (DT.dominates(LHead, RHead))
685 return 1;
686 else
687 assert(DT.dominates(RHead, LHead) &&(static_cast <bool> (DT.dominates(RHead, LHead) &&
"No dominance between recurrences used by one SCEV?") ? void
(0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 688, __extension__ __PRETTY_FUNCTION__))
688 "No dominance between recurrences used by one SCEV?")(static_cast <bool> (DT.dominates(RHead, LHead) &&
"No dominance between recurrences used by one SCEV?") ? void
(0) : __assert_fail ("DT.dominates(RHead, LHead) && \"No dominance between recurrences used by one SCEV?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 688, __extension__ __PRETTY_FUNCTION__))
;
689 return -1;
690 }
691
692 // Addrec complexity grows with operand count.
693 unsigned LNumOps = LA->getNumOperands(), RNumOps = RA->getNumOperands();
694 if (LNumOps != RNumOps)
695 return (int)LNumOps - (int)RNumOps;
696
697 // Compare NoWrap flags.
698 if (LA->getNoWrapFlags() != RA->getNoWrapFlags())
699 return (int)LA->getNoWrapFlags() - (int)RA->getNoWrapFlags();
700
701 // Lexicographically compare.
702 for (unsigned i = 0; i != LNumOps; ++i) {
703 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
704 LA->getOperand(i), RA->getOperand(i), DT,
705 Depth + 1);
706 if (X != 0)
707 return X;
708 }
709 EqCacheSCEV.unionSets(LHS, RHS);
710 return 0;
711 }
712
713 case scAddExpr:
714 case scMulExpr:
715 case scSMaxExpr:
716 case scUMaxExpr: {
717 const SCEVNAryExpr *LC = cast<SCEVNAryExpr>(LHS);
718 const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
719
720 // Lexicographically compare n-ary expressions.
721 unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
722 if (LNumOps != RNumOps)
723 return (int)LNumOps - (int)RNumOps;
724
725 // Compare NoWrap flags.
726 if (LC->getNoWrapFlags() != RC->getNoWrapFlags())
727 return (int)LC->getNoWrapFlags() - (int)RC->getNoWrapFlags();
728
729 for (unsigned i = 0; i != LNumOps; ++i) {
730 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
731 LC->getOperand(i), RC->getOperand(i), DT,
732 Depth + 1);
733 if (X != 0)
734 return X;
735 }
736 EqCacheSCEV.unionSets(LHS, RHS);
737 return 0;
738 }
739
740 case scUDivExpr: {
741 const SCEVUDivExpr *LC = cast<SCEVUDivExpr>(LHS);
742 const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
743
744 // Lexicographically compare udiv expressions.
745 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getLHS(),
746 RC->getLHS(), DT, Depth + 1);
747 if (X != 0)
748 return X;
749 X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, LC->getRHS(),
750 RC->getRHS(), DT, Depth + 1);
751 if (X == 0)
752 EqCacheSCEV.unionSets(LHS, RHS);
753 return X;
754 }
755
756 case scTruncate:
757 case scZeroExtend:
758 case scSignExtend: {
759 const SCEVCastExpr *LC = cast<SCEVCastExpr>(LHS);
760 const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
761
762 // Compare cast expressions by operand.
763 int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
764 LC->getOperand(), RC->getOperand(), DT,
765 Depth + 1);
766 if (X == 0)
767 EqCacheSCEV.unionSets(LHS, RHS);
768 return X;
769 }
770
771 case scCouldNotCompute:
772 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!")::llvm::llvm_unreachable_internal("Attempt to use a SCEVCouldNotCompute object!"
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 772)
;
773 }
774 llvm_unreachable("Unknown SCEV kind!")::llvm::llvm_unreachable_internal("Unknown SCEV kind!", "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 774)
;
775}
776
777/// Given a list of SCEV objects, order them by their complexity, and group
778/// objects of the same complexity together by value. When this routine is
779/// finished, we know that any duplicates in the vector are consecutive and that
780/// complexity is monotonically increasing.
781///
782/// Note that we go take special precautions to ensure that we get deterministic
783/// results from this routine. In other words, we don't want the results of
784/// this to depend on where the addresses of various SCEV objects happened to
785/// land in memory.
786static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops,
787 LoopInfo *LI, DominatorTree &DT) {
788 if (Ops.size() < 2) return; // Noop
789
790 EquivalenceClasses<const SCEV *> EqCacheSCEV;
791 EquivalenceClasses<const Value *> EqCacheValue;
792 if (Ops.size() == 2) {
793 // This is the common case, which also happens to be trivially simple.
794 // Special case it.
795 const SCEV *&LHS = Ops[0], *&RHS = Ops[1];
796 if (CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI, RHS, LHS, DT) < 0)
797 std::swap(LHS, RHS);
798 return;
799 }
800
801 // Do the rough sort by complexity.
802 std::stable_sort(Ops.begin(), Ops.end(),
803 [&](const SCEV *LHS, const SCEV *RHS) {
804 return CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
805 LHS, RHS, DT) < 0;
806 });
807
808 // Now that we are sorted by complexity, group elements of the same
809 // complexity. Note that this is, at worst, N^2, but the vector is likely to
810 // be extremely short in practice. Note that we take this approach because we
811 // do not want to depend on the addresses of the objects we are grouping.
812 for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
813 const SCEV *S = Ops[i];
814 unsigned Complexity = S->getSCEVType();
815
816 // If there are any objects of the same complexity and same value as this
817 // one, group them.
818 for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
819 if (Ops[j] == S) { // Found a duplicate.
820 // Move it to immediately after i'th element.
821 std::swap(Ops[i+1], Ops[j]);
822 ++i; // no need to rescan it.
823 if (i == e-2) return; // Done!
824 }
825 }
826 }
827}
828
829// Returns the size of the SCEV S.
830static inline int sizeOfSCEV(const SCEV *S) {
831 struct FindSCEVSize {
832 int Size = 0;
833
834 FindSCEVSize() = default;
835
836 bool follow(const SCEV *S) {
837 ++Size;
838 // Keep looking at all operands of S.
839 return true;
840 }
841
842 bool isDone() const {
843 return false;
844 }
845 };
846
847 FindSCEVSize F;
848 SCEVTraversal<FindSCEVSize> ST(F);
849 ST.visitAll(S);
850 return F.Size;
851}
852
853namespace {
854
855struct SCEVDivision : public SCEVVisitor<SCEVDivision, void> {
856public:
857 // Computes the Quotient and Remainder of the division of Numerator by
858 // Denominator.
859 static void divide(ScalarEvolution &SE, const SCEV *Numerator,
860 const SCEV *Denominator, const SCEV **Quotient,
861 const SCEV **Remainder) {
862 assert(Numerator && Denominator && "Uninitialized SCEV")(static_cast <bool> (Numerator && Denominator &&
"Uninitialized SCEV") ? void (0) : __assert_fail ("Numerator && Denominator && \"Uninitialized SCEV\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 862, __extension__ __PRETTY_FUNCTION__))
;
863
864 SCEVDivision D(SE, Numerator, Denominator);
865
866 // Check for the trivial case here to avoid having to check for it in the
867 // rest of the code.
868 if (Numerator == Denominator) {
869 *Quotient = D.One;
870 *Remainder = D.Zero;
871 return;
872 }
873
874 if (Numerator->isZero()) {
875 *Quotient = D.Zero;
876 *Remainder = D.Zero;
877 return;
878 }
879
880 // A simple case when N/1. The quotient is N.
881 if (Denominator->isOne()) {
882 *Quotient = Numerator;
883 *Remainder = D.Zero;
884 return;
885 }
886
887 // Split the Denominator when it is a product.
888 if (const SCEVMulExpr *T = dyn_cast<SCEVMulExpr>(Denominator)) {
889 const SCEV *Q, *R;
890 *Quotient = Numerator;
891 for (const SCEV *Op : T->operands()) {
892 divide(SE, *Quotient, Op, &Q, &R);
893 *Quotient = Q;
894
895 // Bail out when the Numerator is not divisible by one of the terms of
896 // the Denominator.
897 if (!R->isZero()) {
898 *Quotient = D.Zero;
899 *Remainder = Numerator;
900 return;
901 }
902 }
903 *Remainder = D.Zero;
904 return;
905 }
906
907 D.visit(Numerator);
908 *Quotient = D.Quotient;
909 *Remainder = D.Remainder;
910 }
911
912 // Except in the trivial case described above, we do not know how to divide
913 // Expr by Denominator for the following functions with empty implementation.
914 void visitTruncateExpr(const SCEVTruncateExpr *Numerator) {}
915 void visitZeroExtendExpr(const SCEVZeroExtendExpr *Numerator) {}
916 void visitSignExtendExpr(const SCEVSignExtendExpr *Numerator) {}
917 void visitUDivExpr(const SCEVUDivExpr *Numerator) {}
918 void visitSMaxExpr(const SCEVSMaxExpr *Numerator) {}
919 void visitUMaxExpr(const SCEVUMaxExpr *Numerator) {}
920 void visitUnknown(const SCEVUnknown *Numerator) {}
921 void visitCouldNotCompute(const SCEVCouldNotCompute *Numerator) {}
922
923 void visitConstant(const SCEVConstant *Numerator) {
924 if (const SCEVConstant *D = dyn_cast<SCEVConstant>(Denominator)) {
925 APInt NumeratorVal = Numerator->getAPInt();
926 APInt DenominatorVal = D->getAPInt();
927 uint32_t NumeratorBW = NumeratorVal.getBitWidth();
928 uint32_t DenominatorBW = DenominatorVal.getBitWidth();
929
930 if (NumeratorBW > DenominatorBW)
931 DenominatorVal = DenominatorVal.sext(NumeratorBW);
932 else if (NumeratorBW < DenominatorBW)
933 NumeratorVal = NumeratorVal.sext(DenominatorBW);
934
935 APInt QuotientVal(NumeratorVal.getBitWidth(), 0);
936 APInt RemainderVal(NumeratorVal.getBitWidth(), 0);
937 APInt::sdivrem(NumeratorVal, DenominatorVal, QuotientVal, RemainderVal);
938 Quotient = SE.getConstant(QuotientVal);
939 Remainder = SE.getConstant(RemainderVal);
940 return;
941 }
942 }
943
944 void visitAddRecExpr(const SCEVAddRecExpr *Numerator) {
945 const SCEV *StartQ, *StartR, *StepQ, *StepR;
946 if (!Numerator->isAffine())
947 return cannotDivide(Numerator);
948 divide(SE, Numerator->getStart(), Denominator, &StartQ, &StartR);
949 divide(SE, Numerator->getStepRecurrence(SE), Denominator, &StepQ, &StepR);
950 // Bail out if the types do not match.
951 Type *Ty = Denominator->getType();
952 if (Ty != StartQ->getType() || Ty != StartR->getType() ||
953 Ty != StepQ->getType() || Ty != StepR->getType())
954 return cannotDivide(Numerator);
955 Quotient = SE.getAddRecExpr(StartQ, StepQ, Numerator->getLoop(),
956 Numerator->getNoWrapFlags());
957 Remainder = SE.getAddRecExpr(StartR, StepR, Numerator->getLoop(),
958 Numerator->getNoWrapFlags());
959 }
960
961 void visitAddExpr(const SCEVAddExpr *Numerator) {
962 SmallVector<const SCEV *, 2> Qs, Rs;
963 Type *Ty = Denominator->getType();
964
965 for (const SCEV *Op : Numerator->operands()) {
966 const SCEV *Q, *R;
967 divide(SE, Op, Denominator, &Q, &R);
968
969 // Bail out if types do not match.
970 if (Ty != Q->getType() || Ty != R->getType())
971 return cannotDivide(Numerator);
972
973 Qs.push_back(Q);
974 Rs.push_back(R);
975 }
976
977 if (Qs.size() == 1) {
978 Quotient = Qs[0];
979 Remainder = Rs[0];
980 return;
981 }
982
983 Quotient = SE.getAddExpr(Qs);
984 Remainder = SE.getAddExpr(Rs);
985 }
986
987 void visitMulExpr(const SCEVMulExpr *Numerator) {
988 SmallVector<const SCEV *, 2> Qs;
989 Type *Ty = Denominator->getType();
990
991 bool FoundDenominatorTerm = false;
992 for (const SCEV *Op : Numerator->operands()) {
993 // Bail out if types do not match.
994 if (Ty != Op->getType())
995 return cannotDivide(Numerator);
996
997 if (FoundDenominatorTerm) {
998 Qs.push_back(Op);
999 continue;
1000 }
1001
1002 // Check whether Denominator divides one of the product operands.
1003 const SCEV *Q, *R;
1004 divide(SE, Op, Denominator, &Q, &R);
1005 if (!R->isZero()) {
1006 Qs.push_back(Op);
1007 continue;
1008 }
1009
1010 // Bail out if types do not match.
1011 if (Ty != Q->getType())
1012 return cannotDivide(Numerator);
1013
1014 FoundDenominatorTerm = true;
1015 Qs.push_back(Q);
1016 }
1017
1018 if (FoundDenominatorTerm) {
1019 Remainder = Zero;
1020 if (Qs.size() == 1)
1021 Quotient = Qs[0];
1022 else
1023 Quotient = SE.getMulExpr(Qs);
1024 return;
1025 }
1026
1027 if (!isa<SCEVUnknown>(Denominator))
1028 return cannotDivide(Numerator);
1029
1030 // The Remainder is obtained by replacing Denominator by 0 in Numerator.
1031 ValueToValueMap RewriteMap;
1032 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
1033 cast<SCEVConstant>(Zero)->getValue();
1034 Remainder = SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
1035
1036 if (Remainder->isZero()) {
1037 // The Quotient is obtained by replacing Denominator by 1 in Numerator.
1038 RewriteMap[cast<SCEVUnknown>(Denominator)->getValue()] =
1039 cast<SCEVConstant>(One)->getValue();
1040 Quotient =
1041 SCEVParameterRewriter::rewrite(Numerator, SE, RewriteMap, true);
1042 return;
1043 }
1044
1045 // Quotient is (Numerator - Remainder) divided by Denominator.
1046 const SCEV *Q, *R;
1047 const SCEV *Diff = SE.getMinusSCEV(Numerator, Remainder);
1048 // This SCEV does not seem to simplify: fail the division here.
1049 if (sizeOfSCEV(Diff) > sizeOfSCEV(Numerator))
1050 return cannotDivide(Numerator);
1051 divide(SE, Diff, Denominator, &Q, &R);
1052 if (R != Zero)
1053 return cannotDivide(Numerator);
1054 Quotient = Q;
1055 }
1056
1057private:
1058 SCEVDivision(ScalarEvolution &S, const SCEV *Numerator,
1059 const SCEV *Denominator)
1060 : SE(S), Denominator(Denominator) {
1061 Zero = SE.getZero(Denominator->getType());
1062 One = SE.getOne(Denominator->getType());
1063
1064 // We generally do not know how to divide Expr by Denominator. We
1065 // initialize the division to a "cannot divide" state to simplify the rest
1066 // of the code.
1067 cannotDivide(Numerator);
1068 }
1069
1070 // Convenience function for giving up on the division. We set the quotient to
1071 // be equal to zero and the remainder to be equal to the numerator.
1072 void cannotDivide(const SCEV *Numerator) {
1073 Quotient = Zero;
1074 Remainder = Numerator;
1075 }
1076
1077 ScalarEvolution &SE;
1078 const SCEV *Denominator, *Quotient, *Remainder, *Zero, *One;
1079};
1080
1081} // end anonymous namespace
1082
1083//===----------------------------------------------------------------------===//
1084// Simple SCEV method implementations
1085//===----------------------------------------------------------------------===//
1086
1087/// Compute BC(It, K). The result has width W. Assume, K > 0.
1088static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
1089 ScalarEvolution &SE,
1090 Type *ResultTy) {
1091 // Handle the simplest case efficiently.
1092 if (K == 1)
1093 return SE.getTruncateOrZeroExtend(It, ResultTy);
1094
1095 // We are using the following formula for BC(It, K):
1096 //
1097 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K!
1098 //
1099 // Suppose, W is the bitwidth of the return value. We must be prepared for
1100 // overflow. Hence, we must assure that the result of our computation is
1101 // equal to the accurate one modulo 2^W. Unfortunately, division isn't
1102 // safe in modular arithmetic.
1103 //
1104 // However, this code doesn't use exactly that formula; the formula it uses
1105 // is something like the following, where T is the number of factors of 2 in
1106 // K! (i.e. trailing zeros in the binary representation of K!), and ^ is
1107 // exponentiation:
1108 //
1109 // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T)
1110 //
1111 // This formula is trivially equivalent to the previous formula. However,
1112 // this formula can be implemented much more efficiently. The trick is that
1113 // K! / 2^T is odd, and exact division by an odd number *is* safe in modular
1114 // arithmetic. To do exact division in modular arithmetic, all we have
1115 // to do is multiply by the inverse. Therefore, this step can be done at
1116 // width W.
1117 //
1118 // The next issue is how to safely do the division by 2^T. The way this
1119 // is done is by doing the multiplication step at a width of at least W + T
1120 // bits. This way, the bottom W+T bits of the product are accurate. Then,
1121 // when we perform the division by 2^T (which is equivalent to a right shift
1122 // by T), the bottom W bits are accurate. Extra bits are okay; they'll get
1123 // truncated out after the division by 2^T.
1124 //
1125 // In comparison to just directly using the first formula, this technique
1126 // is much more efficient; using the first formula requires W * K bits,
1127 // but this formula less than W + K bits. Also, the first formula requires
1128 // a division step, whereas this formula only requires multiplies and shifts.
1129 //
1130 // It doesn't matter whether the subtraction step is done in the calculation
1131 // width or the input iteration count's width; if the subtraction overflows,
1132 // the result must be zero anyway. We prefer here to do it in the width of
1133 // the induction variable because it helps a lot for certain cases; CodeGen
1134 // isn't smart enough to ignore the overflow, which leads to much less
1135 // efficient code if the width of the subtraction is wider than the native
1136 // register width.
1137 //
1138 // (It's possible to not widen at all by pulling out factors of 2 before
1139 // the multiplication; for example, K=2 can be calculated as
1140 // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires
1141 // extra arithmetic, so it's not an obvious win, and it gets
1142 // much more complicated for K > 3.)
1143
1144 // Protection from insane SCEVs; this bound is conservative,
1145 // but it probably doesn't matter.
1146 if (K > 1000)
1147 return SE.getCouldNotCompute();
1148
1149 unsigned W = SE.getTypeSizeInBits(ResultTy);
1150
1151 // Calculate K! / 2^T and T; we divide out the factors of two before
1152 // multiplying for calculating K! / 2^T to avoid overflow.
1153 // Other overflow doesn't matter because we only care about the bottom
1154 // W bits of the result.
1155 APInt OddFactorial(W, 1);
1156 unsigned T = 1;
1157 for (unsigned i = 3; i <= K; ++i) {
1158 APInt Mult(W, i);
1159 unsigned TwoFactors = Mult.countTrailingZeros();
1160 T += TwoFactors;
1161 Mult.lshrInPlace(TwoFactors);
1162 OddFactorial *= Mult;
1163 }
1164
1165 // We need at least W + T bits for the multiplication step
1166 unsigned CalculationBits = W + T;
1167
1168 // Calculate 2^T, at width T+W.
1169 APInt DivFactor = APInt::getOneBitSet(CalculationBits, T);
1170
1171 // Calculate the multiplicative inverse of K! / 2^T;
1172 // this multiplication factor will perform the exact division by
1173 // K! / 2^T.
1174 APInt Mod = APInt::getSignedMinValue(W+1);
1175 APInt MultiplyFactor = OddFactorial.zext(W+1);
1176 MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod);
1177 MultiplyFactor = MultiplyFactor.trunc(W);
1178
1179 // Calculate the product, at width T+W
1180 IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
1181 CalculationBits);
1182 const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
1183 for (unsigned i = 1; i != K; ++i) {
1184 const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
1185 Dividend = SE.getMulExpr(Dividend,
1186 SE.getTruncateOrZeroExtend(S, CalculationTy));
1187 }
1188
1189 // Divide by 2^T
1190 const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor));
1191
1192 // Truncate the result, and divide by K! / 2^T.
1193
1194 return SE.getMulExpr(SE.getConstant(MultiplyFactor),
1195 SE.getTruncateOrZeroExtend(DivResult, ResultTy));
1196}
1197
1198/// Return the value of this chain of recurrences at the specified iteration
1199/// number. We can evaluate this recurrence by multiplying each element in the
1200/// chain by the binomial coefficient corresponding to it. In other words, we
1201/// can evaluate {A,+,B,+,C,+,D} as:
1202///
1203/// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)
1204///
1205/// where BC(It, k) stands for binomial coefficient.
1206const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
1207 ScalarEvolution &SE) const {
1208 const SCEV *Result = getStart();
1209 for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
1210 // The computation is correct in the face of overflow provided that the
1211 // multiplication is performed _after_ the evaluation of the binomial
1212 // coefficient.
1213 const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType());
1214 if (isa<SCEVCouldNotCompute>(Coeff))
1215 return Coeff;
1216
1217 Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));
1218 }
1219 return Result;
1220}
1221
1222//===----------------------------------------------------------------------===//
1223// SCEV Expression folder implementations
1224//===----------------------------------------------------------------------===//
1225
1226const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op,
1227 Type *Ty) {
1228 assert(getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType()
) > getTypeSizeInBits(Ty) && "This is not a truncating conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1229, __extension__ __PRETTY_FUNCTION__))
1229 "This is not a truncating conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType()
) > getTypeSizeInBits(Ty) && "This is not a truncating conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) && \"This is not a truncating conversion!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1229, __extension__ __PRETTY_FUNCTION__))
;
1230 assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1231, __extension__ __PRETTY_FUNCTION__))
1231 "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1231, __extension__ __PRETTY_FUNCTION__))
;
1232 Ty = getEffectiveSCEVType(Ty);
1233
1234 FoldingSetNodeID ID;
1235 ID.AddInteger(scTruncate);
1236 ID.AddPointer(Op);
1237 ID.AddPointer(Ty);
1238 void *IP = nullptr;
1239 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1240
1241 // Fold if the operand is constant.
1242 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1243 return getConstant(
1244 cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(), Ty)));
1245
1246 // trunc(trunc(x)) --> trunc(x)
1247 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
1248 return getTruncateExpr(ST->getOperand(), Ty);
1249
1250 // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
1251 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1252 return getTruncateOrSignExtend(SS->getOperand(), Ty);
1253
1254 // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
1255 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1256 return getTruncateOrZeroExtend(SZ->getOperand(), Ty);
1257
1258 // trunc(x1+x2+...+xN) --> trunc(x1)+trunc(x2)+...+trunc(xN) if we can
1259 // eliminate all the truncates, or we replace other casts with truncates.
1260 if (const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Op)) {
1261 SmallVector<const SCEV *, 4> Operands;
1262 bool hasTrunc = false;
1263 for (unsigned i = 0, e = SA->getNumOperands(); i != e && !hasTrunc; ++i) {
1264 const SCEV *S = getTruncateExpr(SA->getOperand(i), Ty);
1265 if (!isa<SCEVCastExpr>(SA->getOperand(i)))
1266 hasTrunc = isa<SCEVTruncateExpr>(S);
1267 Operands.push_back(S);
1268 }
1269 if (!hasTrunc)
1270 return getAddExpr(Operands);
1271 // In spite we checked in the beginning that ID is not in the cache,
1272 // it is possible that during recursion and different modification
1273 // ID came to cache, so if we found it, just return it.
1274 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
1275 return S;
1276 }
1277
1278 // trunc(x1*x2*...*xN) --> trunc(x1)*trunc(x2)*...*trunc(xN) if we can
1279 // eliminate all the truncates, or we replace other casts with truncates.
1280 if (const SCEVMulExpr *SM = dyn_cast<SCEVMulExpr>(Op)) {
1281 SmallVector<const SCEV *, 4> Operands;
1282 bool hasTrunc = false;
1283 for (unsigned i = 0, e = SM->getNumOperands(); i != e && !hasTrunc; ++i) {
1284 const SCEV *S = getTruncateExpr(SM->getOperand(i), Ty);
1285 if (!isa<SCEVCastExpr>(SM->getOperand(i)))
1286 hasTrunc = isa<SCEVTruncateExpr>(S);
1287 Operands.push_back(S);
1288 }
1289 if (!hasTrunc)
1290 return getMulExpr(Operands);
1291 // In spite we checked in the beginning that ID is not in the cache,
1292 // it is possible that during recursion and different modification
1293 // ID came to cache, so if we found it, just return it.
1294 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP))
1295 return S;
1296 }
1297
1298 // If the input value is a chrec scev, truncate the chrec's operands.
1299 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
1300 SmallVector<const SCEV *, 4> Operands;
1301 for (const SCEV *Op : AddRec->operands())
1302 Operands.push_back(getTruncateExpr(Op, Ty));
1303 return getAddRecExpr(Operands, AddRec->getLoop(), SCEV::FlagAnyWrap);
1304 }
1305
1306 // The cast wasn't folded; create an explicit cast node. We can reuse
1307 // the existing insert position since if we get here, we won't have
1308 // made any changes which would invalidate it.
1309 SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
1310 Op, Ty);
1311 UniqueSCEVs.InsertNode(S, IP);
1312 addToLoopUseLists(S);
1313 return S;
1314}
1315
1316// Get the limit of a recurrence such that incrementing by Step cannot cause
1317// signed overflow as long as the value of the recurrence within the
1318// loop does not exceed this limit before incrementing.
1319static const SCEV *getSignedOverflowLimitForStep(const SCEV *Step,
1320 ICmpInst::Predicate *Pred,
1321 ScalarEvolution *SE) {
1322 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1323 if (SE->isKnownPositive(Step)) {
1324 *Pred = ICmpInst::ICMP_SLT;
1325 return SE->getConstant(APInt::getSignedMinValue(BitWidth) -
1326 SE->getSignedRangeMax(Step));
1327 }
1328 if (SE->isKnownNegative(Step)) {
1329 *Pred = ICmpInst::ICMP_SGT;
1330 return SE->getConstant(APInt::getSignedMaxValue(BitWidth) -
1331 SE->getSignedRangeMin(Step));
1332 }
1333 return nullptr;
1334}
1335
1336// Get the limit of a recurrence such that incrementing by Step cannot cause
1337// unsigned overflow as long as the value of the recurrence within the loop does
1338// not exceed this limit before incrementing.
1339static const SCEV *getUnsignedOverflowLimitForStep(const SCEV *Step,
1340 ICmpInst::Predicate *Pred,
1341 ScalarEvolution *SE) {
1342 unsigned BitWidth = SE->getTypeSizeInBits(Step->getType());
1343 *Pred = ICmpInst::ICMP_ULT;
1344
1345 return SE->getConstant(APInt::getMinValue(BitWidth) -
1346 SE->getUnsignedRangeMax(Step));
1347}
1348
1349namespace {
1350
1351struct ExtendOpTraitsBase {
1352 typedef const SCEV *(ScalarEvolution::*GetExtendExprTy)(const SCEV *, Type *,
1353 unsigned);
1354};
1355
1356// Used to make code generic over signed and unsigned overflow.
1357template <typename ExtendOp> struct ExtendOpTraits {
1358 // Members present:
1359 //
1360 // static const SCEV::NoWrapFlags WrapType;
1361 //
1362 // static const ExtendOpTraitsBase::GetExtendExprTy GetExtendExpr;
1363 //
1364 // static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1365 // ICmpInst::Predicate *Pred,
1366 // ScalarEvolution *SE);
1367};
1368
1369template <>
1370struct ExtendOpTraits<SCEVSignExtendExpr> : public ExtendOpTraitsBase {
1371 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNSW;
1372
1373 static const GetExtendExprTy GetExtendExpr;
1374
1375 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1376 ICmpInst::Predicate *Pred,
1377 ScalarEvolution *SE) {
1378 return getSignedOverflowLimitForStep(Step, Pred, SE);
1379 }
1380};
1381
1382const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1383 SCEVSignExtendExpr>::GetExtendExpr = &ScalarEvolution::getSignExtendExpr;
1384
1385template <>
1386struct ExtendOpTraits<SCEVZeroExtendExpr> : public ExtendOpTraitsBase {
1387 static const SCEV::NoWrapFlags WrapType = SCEV::FlagNUW;
1388
1389 static const GetExtendExprTy GetExtendExpr;
1390
1391 static const SCEV *getOverflowLimitForStep(const SCEV *Step,
1392 ICmpInst::Predicate *Pred,
1393 ScalarEvolution *SE) {
1394 return getUnsignedOverflowLimitForStep(Step, Pred, SE);
1395 }
1396};
1397
1398const ExtendOpTraitsBase::GetExtendExprTy ExtendOpTraits<
1399 SCEVZeroExtendExpr>::GetExtendExpr = &ScalarEvolution::getZeroExtendExpr;
1400
1401} // end anonymous namespace
1402
1403// The recurrence AR has been shown to have no signed/unsigned wrap or something
1404// close to it. Typically, if we can prove NSW/NUW for AR, then we can just as
1405// easily prove NSW/NUW for its preincrement or postincrement sibling. This
1406// allows normalizing a sign/zero extended AddRec as such: {sext/zext(Step +
1407// Start),+,Step} => {(Step + sext/zext(Start),+,Step} As a result, the
1408// expression "Step + sext/zext(PreIncAR)" is congruent with
1409// "sext/zext(PostIncAR)"
1410template <typename ExtendOpTy>
1411static const SCEV *getPreStartForExtend(const SCEVAddRecExpr *AR, Type *Ty,
1412 ScalarEvolution *SE, unsigned Depth) {
1413 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1414 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1415
1416 const Loop *L = AR->getLoop();
1417 const SCEV *Start = AR->getStart();
1418 const SCEV *Step = AR->getStepRecurrence(*SE);
1419
1420 // Check for a simple looking step prior to loop entry.
1421 const SCEVAddExpr *SA = dyn_cast<SCEVAddExpr>(Start);
1422 if (!SA)
1423 return nullptr;
1424
1425 // Create an AddExpr for "PreStart" after subtracting Step. Full SCEV
1426 // subtraction is expensive. For this purpose, perform a quick and dirty
1427 // difference, by checking for Step in the operand list.
1428 SmallVector<const SCEV *, 4> DiffOps;
1429 for (const SCEV *Op : SA->operands())
1430 if (Op != Step)
1431 DiffOps.push_back(Op);
1432
1433 if (DiffOps.size() == SA->getNumOperands())
1434 return nullptr;
1435
1436 // Try to prove `WrapType` (SCEV::FlagNSW or SCEV::FlagNUW) on `PreStart` +
1437 // `Step`:
1438
1439 // 1. NSW/NUW flags on the step increment.
1440 auto PreStartFlags =
1441 ScalarEvolution::maskFlags(SA->getNoWrapFlags(), SCEV::FlagNUW);
1442 const SCEV *PreStart = SE->getAddExpr(DiffOps, PreStartFlags);
1443 const SCEVAddRecExpr *PreAR = dyn_cast<SCEVAddRecExpr>(
1444 SE->getAddRecExpr(PreStart, Step, L, SCEV::FlagAnyWrap));
1445
1446 // "{S,+,X} is <nsw>/<nuw>" and "the backedge is taken at least once" implies
1447 // "S+X does not sign/unsign-overflow".
1448 //
1449
1450 const SCEV *BECount = SE->getBackedgeTakenCount(L);
1451 if (PreAR && PreAR->getNoWrapFlags(WrapType) &&
1452 !isa<SCEVCouldNotCompute>(BECount) && SE->isKnownPositive(BECount))
1453 return PreStart;
1454
1455 // 2. Direct overflow check on the step operation's expression.
1456 unsigned BitWidth = SE->getTypeSizeInBits(AR->getType());
1457 Type *WideTy = IntegerType::get(SE->getContext(), BitWidth * 2);
1458 const SCEV *OperandExtendedStart =
1459 SE->getAddExpr((SE->*GetExtendExpr)(PreStart, WideTy, Depth),
1460 (SE->*GetExtendExpr)(Step, WideTy, Depth));
1461 if ((SE->*GetExtendExpr)(Start, WideTy, Depth) == OperandExtendedStart) {
1462 if (PreAR && AR->getNoWrapFlags(WrapType)) {
1463 // If we know `AR` == {`PreStart`+`Step`,+,`Step`} is `WrapType` (FlagNSW
1464 // or FlagNUW) and that `PreStart` + `Step` is `WrapType` too, then
1465 // `PreAR` == {`PreStart`,+,`Step`} is also `WrapType`. Cache this fact.
1466 const_cast<SCEVAddRecExpr *>(PreAR)->setNoWrapFlags(WrapType);
1467 }
1468 return PreStart;
1469 }
1470
1471 // 3. Loop precondition.
1472 ICmpInst::Predicate Pred;
1473 const SCEV *OverflowLimit =
1474 ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(Step, &Pred, SE);
1475
1476 if (OverflowLimit &&
1477 SE->isLoopEntryGuardedByCond(L, Pred, PreStart, OverflowLimit))
1478 return PreStart;
1479
1480 return nullptr;
1481}
1482
1483// Get the normalized zero or sign extended expression for this AddRec's Start.
1484template <typename ExtendOpTy>
1485static const SCEV *getExtendAddRecStart(const SCEVAddRecExpr *AR, Type *Ty,
1486 ScalarEvolution *SE,
1487 unsigned Depth) {
1488 auto GetExtendExpr = ExtendOpTraits<ExtendOpTy>::GetExtendExpr;
1489
1490 const SCEV *PreStart = getPreStartForExtend<ExtendOpTy>(AR, Ty, SE, Depth);
1491 if (!PreStart)
1492 return (SE->*GetExtendExpr)(AR->getStart(), Ty, Depth);
1493
1494 return SE->getAddExpr((SE->*GetExtendExpr)(AR->getStepRecurrence(*SE), Ty,
1495 Depth),
1496 (SE->*GetExtendExpr)(PreStart, Ty, Depth));
1497}
1498
1499// Try to prove away overflow by looking at "nearby" add recurrences. A
1500// motivating example for this rule: if we know `{0,+,4}` is `ult` `-1` and it
1501// does not itself wrap then we can conclude that `{1,+,4}` is `nuw`.
1502//
1503// Formally:
1504//
1505// {S,+,X} == {S-T,+,X} + T
1506// => Ext({S,+,X}) == Ext({S-T,+,X} + T)
1507//
1508// If ({S-T,+,X} + T) does not overflow ... (1)
1509//
1510// RHS == Ext({S-T,+,X} + T) == Ext({S-T,+,X}) + Ext(T)
1511//
1512// If {S-T,+,X} does not overflow ... (2)
1513//
1514// RHS == Ext({S-T,+,X}) + Ext(T) == {Ext(S-T),+,Ext(X)} + Ext(T)
1515// == {Ext(S-T)+Ext(T),+,Ext(X)}
1516//
1517// If (S-T)+T does not overflow ... (3)
1518//
1519// RHS == {Ext(S-T)+Ext(T),+,Ext(X)} == {Ext(S-T+T),+,Ext(X)}
1520// == {Ext(S),+,Ext(X)} == LHS
1521//
1522// Thus, if (1), (2) and (3) are true for some T, then
1523// Ext({S,+,X}) == {Ext(S),+,Ext(X)}
1524//
1525// (3) is implied by (1) -- "(S-T)+T does not overflow" is simply "({S-T,+,X}+T)
1526// does not overflow" restricted to the 0th iteration. Therefore we only need
1527// to check for (1) and (2).
1528//
1529// In the current context, S is `Start`, X is `Step`, Ext is `ExtendOpTy` and T
1530// is `Delta` (defined below).
1531template <typename ExtendOpTy>
1532bool ScalarEvolution::proveNoWrapByVaryingStart(const SCEV *Start,
1533 const SCEV *Step,
1534 const Loop *L) {
1535 auto WrapType = ExtendOpTraits<ExtendOpTy>::WrapType;
1536
1537 // We restrict `Start` to a constant to prevent SCEV from spending too much
1538 // time here. It is correct (but more expensive) to continue with a
1539 // non-constant `Start` and do a general SCEV subtraction to compute
1540 // `PreStart` below.
1541 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start);
1542 if (!StartC)
1543 return false;
1544
1545 APInt StartAI = StartC->getAPInt();
1546
1547 for (unsigned Delta : {-2, -1, 1, 2}) {
1548 const SCEV *PreStart = getConstant(StartAI - Delta);
1549
1550 FoldingSetNodeID ID;
1551 ID.AddInteger(scAddRecExpr);
1552 ID.AddPointer(PreStart);
1553 ID.AddPointer(Step);
1554 ID.AddPointer(L);
1555 void *IP = nullptr;
1556 const auto *PreAR =
1557 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
1558
1559 // Give up if we don't already have the add recurrence we need because
1560 // actually constructing an add recurrence is relatively expensive.
1561 if (PreAR && PreAR->getNoWrapFlags(WrapType)) { // proves (2)
1562 const SCEV *DeltaS = getConstant(StartC->getType(), Delta);
1563 ICmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
1564 const SCEV *Limit = ExtendOpTraits<ExtendOpTy>::getOverflowLimitForStep(
1565 DeltaS, &Pred, this);
1566 if (Limit && isKnownPredicate(Pred, PreAR, Limit)) // proves (1)
1567 return true;
1568 }
1569 }
1570
1571 return false;
1572}
1573
1574const SCEV *
1575ScalarEvolution::getZeroExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1576 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1577, __extension__ __PRETTY_FUNCTION__))
1577 "This is not an extending conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1577, __extension__ __PRETTY_FUNCTION__))
;
1578 assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1579, __extension__ __PRETTY_FUNCTION__))
1579 "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1579, __extension__ __PRETTY_FUNCTION__))
;
1580 Ty = getEffectiveSCEVType(Ty);
1581
1582 // Fold if the operand is constant.
1583 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1584 return getConstant(
1585 cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(), Ty)));
1586
1587 // zext(zext(x)) --> zext(x)
1588 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1589 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1590
1591 // Before doing any expensive analysis, check to see if we've already
1592 // computed a SCEV for this Op and Ty.
1593 FoldingSetNodeID ID;
1594 ID.AddInteger(scZeroExtend);
1595 ID.AddPointer(Op);
1596 ID.AddPointer(Ty);
1597 void *IP = nullptr;
1598 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1599 if (Depth > MaxExtDepth) {
1600 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1601 Op, Ty);
1602 UniqueSCEVs.InsertNode(S, IP);
1603 addToLoopUseLists(S);
1604 return S;
1605 }
1606
1607 // zext(trunc(x)) --> zext(x) or x or trunc(x)
1608 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1609 // It's possible the bits taken off by the truncate were all zero bits. If
1610 // so, we should be able to simplify this further.
1611 const SCEV *X = ST->getOperand();
1612 ConstantRange CR = getUnsignedRange(X);
1613 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1614 unsigned NewBits = getTypeSizeInBits(Ty);
1615 if (CR.truncate(TruncBits).zeroExtend(NewBits).contains(
1616 CR.zextOrTrunc(NewBits)))
1617 return getTruncateOrZeroExtend(X, Ty);
1618 }
1619
1620 // If the input value is a chrec scev, and we can prove that the value
1621 // did not overflow the old, smaller, value, we can zero extend all of the
1622 // operands (often constants). This allows analysis of something like
1623 // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
1624 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1625 if (AR->isAffine()) {
1626 const SCEV *Start = AR->getStart();
1627 const SCEV *Step = AR->getStepRecurrence(*this);
1628 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1629 const Loop *L = AR->getLoop();
1630
1631 if (!AR->hasNoUnsignedWrap()) {
1632 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1633 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1634 }
1635
1636 // If we have special knowledge that this addrec won't overflow,
1637 // we don't need to do any further analysis.
1638 if (AR->hasNoUnsignedWrap())
1639 return getAddRecExpr(
1640 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1641 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1642
1643 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1644 // Note that this serves two purposes: It filters out loops that are
1645 // simply not analyzable, and it covers the case where this code is
1646 // being called from within backedge-taken count analysis, such that
1647 // attempting to ask for the backedge-taken count would likely result
1648 // in infinite recursion. In the later case, the analysis code will
1649 // cope with a conservative value, and it will take care to purge
1650 // that value once it has finished.
1651 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
1652 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1653 // Manually compute the final value for AR, checking for
1654 // overflow.
1655
1656 // Check whether the backedge-taken count can be losslessly casted to
1657 // the addrec's type. The count is always unsigned.
1658 const SCEV *CastedMaxBECount =
1659 getTruncateOrZeroExtend(MaxBECount, Start->getType());
1660 const SCEV *RecastedMaxBECount =
1661 getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
1662 if (MaxBECount == RecastedMaxBECount) {
1663 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1664 // Check whether Start+Step*MaxBECount has no unsigned overflow.
1665 const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step,
1666 SCEV::FlagAnyWrap, Depth + 1);
1667 const SCEV *ZAdd = getZeroExtendExpr(getAddExpr(Start, ZMul,
1668 SCEV::FlagAnyWrap,
1669 Depth + 1),
1670 WideTy, Depth + 1);
1671 const SCEV *WideStart = getZeroExtendExpr(Start, WideTy, Depth + 1);
1672 const SCEV *WideMaxBECount =
1673 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1674 const SCEV *OperandExtendedAdd =
1675 getAddExpr(WideStart,
1676 getMulExpr(WideMaxBECount,
1677 getZeroExtendExpr(Step, WideTy, Depth + 1),
1678 SCEV::FlagAnyWrap, Depth + 1),
1679 SCEV::FlagAnyWrap, Depth + 1);
1680 if (ZAdd == OperandExtendedAdd) {
1681 // Cache knowledge of AR NUW, which is propagated to this AddRec.
1682 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1683 // Return the expression with the addrec on the outside.
1684 return getAddRecExpr(
1685 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1686 Depth + 1),
1687 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1688 AR->getNoWrapFlags());
1689 }
1690 // Similar to above, only this time treat the step value as signed.
1691 // This covers loops that count down.
1692 OperandExtendedAdd =
1693 getAddExpr(WideStart,
1694 getMulExpr(WideMaxBECount,
1695 getSignExtendExpr(Step, WideTy, Depth + 1),
1696 SCEV::FlagAnyWrap, Depth + 1),
1697 SCEV::FlagAnyWrap, Depth + 1);
1698 if (ZAdd == OperandExtendedAdd) {
1699 // Cache knowledge of AR NW, which is propagated to this AddRec.
1700 // Negative step causes unsigned wrap, but it still can't self-wrap.
1701 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1702 // Return the expression with the addrec on the outside.
1703 return getAddRecExpr(
1704 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1705 Depth + 1),
1706 getSignExtendExpr(Step, Ty, Depth + 1), L,
1707 AR->getNoWrapFlags());
1708 }
1709 }
1710 }
1711
1712 // Normally, in the cases we can prove no-overflow via a
1713 // backedge guarding condition, we can also compute a backedge
1714 // taken count for the loop. The exceptions are assumptions and
1715 // guards present in the loop -- SCEV is not great at exploiting
1716 // these to compute max backedge taken counts, but can still use
1717 // these to prove lack of overflow. Use this fact to avoid
1718 // doing extra work that may not pay off.
1719 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1720 !AC.assumptions().empty()) {
1721 // If the backedge is guarded by a comparison with the pre-inc
1722 // value the addrec is safe. Also, if the entry is guarded by
1723 // a comparison with the start value and the backedge is
1724 // guarded by a comparison with the post-inc value, the addrec
1725 // is safe.
1726 if (isKnownPositive(Step)) {
1727 const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
1728 getUnsignedRangeMax(Step));
1729 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
1730 isKnownOnEveryIteration(ICmpInst::ICMP_ULT, AR, N)) {
1731 // Cache knowledge of AR NUW, which is propagated to this
1732 // AddRec.
1733 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1734 // Return the expression with the addrec on the outside.
1735 return getAddRecExpr(
1736 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1737 Depth + 1),
1738 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1739 AR->getNoWrapFlags());
1740 }
1741 } else if (isKnownNegative(Step)) {
1742 const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
1743 getSignedRangeMin(Step));
1744 if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
1745 isKnownOnEveryIteration(ICmpInst::ICMP_UGT, AR, N)) {
1746 // Cache knowledge of AR NW, which is propagated to this
1747 // AddRec. Negative step causes unsigned wrap, but it
1748 // still can't self-wrap.
1749 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1750 // Return the expression with the addrec on the outside.
1751 return getAddRecExpr(
1752 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this,
1753 Depth + 1),
1754 getSignExtendExpr(Step, Ty, Depth + 1), L,
1755 AR->getNoWrapFlags());
1756 }
1757 }
1758 }
1759
1760 if (proveNoWrapByVaryingStart<SCEVZeroExtendExpr>(Start, Step, L)) {
1761 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNUW);
1762 return getAddRecExpr(
1763 getExtendAddRecStart<SCEVZeroExtendExpr>(AR, Ty, this, Depth + 1),
1764 getZeroExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1765 }
1766 }
1767
1768 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1769 // zext((A + B + ...)<nuw>) --> (zext(A) + zext(B) + ...)<nuw>
1770 if (SA->hasNoUnsignedWrap()) {
1771 // If the addition does not unsign overflow then we can, by definition,
1772 // commute the zero extension with the addition operation.
1773 SmallVector<const SCEV *, 4> Ops;
1774 for (const auto *Op : SA->operands())
1775 Ops.push_back(getZeroExtendExpr(Op, Ty, Depth + 1));
1776 return getAddExpr(Ops, SCEV::FlagNUW, Depth + 1);
1777 }
1778 }
1779
1780 // The cast wasn't folded; create an explicit cast node.
1781 // Recompute the insert position, as it may have been invalidated.
1782 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1783 SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
1784 Op, Ty);
1785 UniqueSCEVs.InsertNode(S, IP);
1786 addToLoopUseLists(S);
1787 return S;
1788}
1789
1790const SCEV *
1791ScalarEvolution::getSignExtendExpr(const SCEV *Op, Type *Ty, unsigned Depth) {
1792 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1793, __extension__ __PRETTY_FUNCTION__))
1793 "This is not an extending conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1793, __extension__ __PRETTY_FUNCTION__))
;
1794 assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1795, __extension__ __PRETTY_FUNCTION__))
1795 "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 1795, __extension__ __PRETTY_FUNCTION__))
;
1796 Ty = getEffectiveSCEVType(Ty);
1797
1798 // Fold if the operand is constant.
1799 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
1800 return getConstant(
1801 cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(), Ty)));
1802
1803 // sext(sext(x)) --> sext(x)
1804 if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
1805 return getSignExtendExpr(SS->getOperand(), Ty, Depth + 1);
1806
1807 // sext(zext(x)) --> zext(x)
1808 if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
1809 return getZeroExtendExpr(SZ->getOperand(), Ty, Depth + 1);
1810
1811 // Before doing any expensive analysis, check to see if we've already
1812 // computed a SCEV for this Op and Ty.
1813 FoldingSetNodeID ID;
1814 ID.AddInteger(scSignExtend);
1815 ID.AddPointer(Op);
1816 ID.AddPointer(Ty);
1817 void *IP = nullptr;
1818 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
1819 // Limit recursion depth.
1820 if (Depth > MaxExtDepth) {
1821 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
1822 Op, Ty);
1823 UniqueSCEVs.InsertNode(S, IP);
1824 addToLoopUseLists(S);
1825 return S;
1826 }
1827
1828 // sext(trunc(x)) --> sext(x) or x or trunc(x)
1829 if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op)) {
1830 // It's possible the bits taken off by the truncate were all sign bits. If
1831 // so, we should be able to simplify this further.
1832 const SCEV *X = ST->getOperand();
1833 ConstantRange CR = getSignedRange(X);
1834 unsigned TruncBits = getTypeSizeInBits(ST->getType());
1835 unsigned NewBits = getTypeSizeInBits(Ty);
1836 if (CR.truncate(TruncBits).signExtend(NewBits).contains(
1837 CR.sextOrTrunc(NewBits)))
1838 return getTruncateOrSignExtend(X, Ty);
1839 }
1840
1841 // sext(C1 + (C2 * x)) --> C1 + sext(C2 * x) if C1 < C2
1842 if (auto *SA = dyn_cast<SCEVAddExpr>(Op)) {
1843 if (SA->getNumOperands() == 2) {
1844 auto *SC1 = dyn_cast<SCEVConstant>(SA->getOperand(0));
1845 auto *SMul = dyn_cast<SCEVMulExpr>(SA->getOperand(1));
1846 if (SMul && SC1) {
1847 if (auto *SC2 = dyn_cast<SCEVConstant>(SMul->getOperand(0))) {
1848 const APInt &C1 = SC1->getAPInt();
1849 const APInt &C2 = SC2->getAPInt();
1850 if (C1.isStrictlyPositive() && C2.isStrictlyPositive() &&
1851 C2.ugt(C1) && C2.isPowerOf2())
1852 return getAddExpr(getSignExtendExpr(SC1, Ty, Depth + 1),
1853 getSignExtendExpr(SMul, Ty, Depth + 1),
1854 SCEV::FlagAnyWrap, Depth + 1);
1855 }
1856 }
1857 }
1858
1859 // sext((A + B + ...)<nsw>) --> (sext(A) + sext(B) + ...)<nsw>
1860 if (SA->hasNoSignedWrap()) {
1861 // If the addition does not sign overflow then we can, by definition,
1862 // commute the sign extension with the addition operation.
1863 SmallVector<const SCEV *, 4> Ops;
1864 for (const auto *Op : SA->operands())
1865 Ops.push_back(getSignExtendExpr(Op, Ty, Depth + 1));
1866 return getAddExpr(Ops, SCEV::FlagNSW, Depth + 1);
1867 }
1868 }
1869 // If the input value is a chrec scev, and we can prove that the value
1870 // did not overflow the old, smaller, value, we can sign extend all of the
1871 // operands (often constants). This allows analysis of something like
1872 // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
1873 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
1874 if (AR->isAffine()) {
1875 const SCEV *Start = AR->getStart();
1876 const SCEV *Step = AR->getStepRecurrence(*this);
1877 unsigned BitWidth = getTypeSizeInBits(AR->getType());
1878 const Loop *L = AR->getLoop();
1879
1880 if (!AR->hasNoSignedWrap()) {
1881 auto NewFlags = proveNoWrapViaConstantRanges(AR);
1882 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(NewFlags);
1883 }
1884
1885 // If we have special knowledge that this addrec won't overflow,
1886 // we don't need to do any further analysis.
1887 if (AR->hasNoSignedWrap())
1888 return getAddRecExpr(
1889 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
1890 getSignExtendExpr(Step, Ty, Depth + 1), L, SCEV::FlagNSW);
1891
1892 // Check whether the backedge-taken count is SCEVCouldNotCompute.
1893 // Note that this serves two purposes: It filters out loops that are
1894 // simply not analyzable, and it covers the case where this code is
1895 // being called from within backedge-taken count analysis, such that
1896 // attempting to ask for the backedge-taken count would likely result
1897 // in infinite recursion. In the later case, the analysis code will
1898 // cope with a conservative value, and it will take care to purge
1899 // that value once it has finished.
1900 const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
1901 if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
1902 // Manually compute the final value for AR, checking for
1903 // overflow.
1904
1905 // Check whether the backedge-taken count can be losslessly casted to
1906 // the addrec's type. The count is always unsigned.
1907 const SCEV *CastedMaxBECount =
1908 getTruncateOrZeroExtend(MaxBECount, Start->getType());
1909 const SCEV *RecastedMaxBECount =
1910 getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
1911 if (MaxBECount == RecastedMaxBECount) {
1912 Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
1913 // Check whether Start+Step*MaxBECount has no signed overflow.
1914 const SCEV *SMul = getMulExpr(CastedMaxBECount, Step,
1915 SCEV::FlagAnyWrap, Depth + 1);
1916 const SCEV *SAdd = getSignExtendExpr(getAddExpr(Start, SMul,
1917 SCEV::FlagAnyWrap,
1918 Depth + 1),
1919 WideTy, Depth + 1);
1920 const SCEV *WideStart = getSignExtendExpr(Start, WideTy, Depth + 1);
1921 const SCEV *WideMaxBECount =
1922 getZeroExtendExpr(CastedMaxBECount, WideTy, Depth + 1);
1923 const SCEV *OperandExtendedAdd =
1924 getAddExpr(WideStart,
1925 getMulExpr(WideMaxBECount,
1926 getSignExtendExpr(Step, WideTy, Depth + 1),
1927 SCEV::FlagAnyWrap, Depth + 1),
1928 SCEV::FlagAnyWrap, Depth + 1);
1929 if (SAdd == OperandExtendedAdd) {
1930 // Cache knowledge of AR NSW, which is propagated to this AddRec.
1931 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1932 // Return the expression with the addrec on the outside.
1933 return getAddRecExpr(
1934 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
1935 Depth + 1),
1936 getSignExtendExpr(Step, Ty, Depth + 1), L,
1937 AR->getNoWrapFlags());
1938 }
1939 // Similar to above, only this time treat the step value as unsigned.
1940 // This covers loops that count up with an unsigned step.
1941 OperandExtendedAdd =
1942 getAddExpr(WideStart,
1943 getMulExpr(WideMaxBECount,
1944 getZeroExtendExpr(Step, WideTy, Depth + 1),
1945 SCEV::FlagAnyWrap, Depth + 1),
1946 SCEV::FlagAnyWrap, Depth + 1);
1947 if (SAdd == OperandExtendedAdd) {
1948 // If AR wraps around then
1949 //
1950 // abs(Step) * MaxBECount > unsigned-max(AR->getType())
1951 // => SAdd != OperandExtendedAdd
1952 //
1953 // Thus (AR is not NW => SAdd != OperandExtendedAdd) <=>
1954 // (SAdd == OperandExtendedAdd => AR is NW)
1955
1956 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNW);
1957
1958 // Return the expression with the addrec on the outside.
1959 return getAddRecExpr(
1960 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this,
1961 Depth + 1),
1962 getZeroExtendExpr(Step, Ty, Depth + 1), L,
1963 AR->getNoWrapFlags());
1964 }
1965 }
1966 }
1967
1968 // Normally, in the cases we can prove no-overflow via a
1969 // backedge guarding condition, we can also compute a backedge
1970 // taken count for the loop. The exceptions are assumptions and
1971 // guards present in the loop -- SCEV is not great at exploiting
1972 // these to compute max backedge taken counts, but can still use
1973 // these to prove lack of overflow. Use this fact to avoid
1974 // doing extra work that may not pay off.
1975
1976 if (!isa<SCEVCouldNotCompute>(MaxBECount) || HasGuards ||
1977 !AC.assumptions().empty()) {
1978 // If the backedge is guarded by a comparison with the pre-inc
1979 // value the addrec is safe. Also, if the entry is guarded by
1980 // a comparison with the start value and the backedge is
1981 // guarded by a comparison with the post-inc value, the addrec
1982 // is safe.
1983 ICmpInst::Predicate Pred;
1984 const SCEV *OverflowLimit =
1985 getSignedOverflowLimitForStep(Step, &Pred, this);
1986 if (OverflowLimit &&
1987 (isLoopBackedgeGuardedByCond(L, Pred, AR, OverflowLimit) ||
1988 isKnownOnEveryIteration(Pred, AR, OverflowLimit))) {
1989 // Cache knowledge of AR NSW, then propagate NSW to the wide AddRec.
1990 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
1991 return getAddRecExpr(
1992 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
1993 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
1994 }
1995 }
1996
1997 // If Start and Step are constants, check if we can apply this
1998 // transformation:
1999 // sext{C1,+,C2} --> C1 + sext{0,+,C2} if C1 < C2
2000 auto *SC1 = dyn_cast<SCEVConstant>(Start);
2001 auto *SC2 = dyn_cast<SCEVConstant>(Step);
2002 if (SC1 && SC2) {
2003 const APInt &C1 = SC1->getAPInt();
2004 const APInt &C2 = SC2->getAPInt();
2005 if (C1.isStrictlyPositive() && C2.isStrictlyPositive() && C2.ugt(C1) &&
2006 C2.isPowerOf2()) {
2007 Start = getSignExtendExpr(Start, Ty, Depth + 1);
2008 const SCEV *NewAR = getAddRecExpr(getZero(AR->getType()), Step, L,
2009 AR->getNoWrapFlags());
2010 return getAddExpr(Start, getSignExtendExpr(NewAR, Ty, Depth + 1),
2011 SCEV::FlagAnyWrap, Depth + 1);
2012 }
2013 }
2014
2015 if (proveNoWrapByVaryingStart<SCEVSignExtendExpr>(Start, Step, L)) {
2016 const_cast<SCEVAddRecExpr *>(AR)->setNoWrapFlags(SCEV::FlagNSW);
2017 return getAddRecExpr(
2018 getExtendAddRecStart<SCEVSignExtendExpr>(AR, Ty, this, Depth + 1),
2019 getSignExtendExpr(Step, Ty, Depth + 1), L, AR->getNoWrapFlags());
2020 }
2021 }
2022
2023 // If the input value is provably positive and we could not simplify
2024 // away the sext build a zext instead.
2025 if (isKnownNonNegative(Op))
2026 return getZeroExtendExpr(Op, Ty, Depth + 1);
2027
2028 // The cast wasn't folded; create an explicit cast node.
2029 // Recompute the insert position, as it may have been invalidated.
2030 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
2031 SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
2032 Op, Ty);
2033 UniqueSCEVs.InsertNode(S, IP);
2034 addToLoopUseLists(S);
2035 return S;
2036}
2037
2038/// getAnyExtendExpr - Return a SCEV for the given operand extended with
2039/// unspecified bits out to the given type.
2040const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
2041 Type *Ty) {
2042 assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2043, __extension__ __PRETTY_FUNCTION__))
2043 "This is not an extending conversion!")(static_cast <bool> (getTypeSizeInBits(Op->getType()
) < getTypeSizeInBits(Ty) && "This is not an extending conversion!"
) ? void (0) : __assert_fail ("getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) && \"This is not an extending conversion!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2043, __extension__ __PRETTY_FUNCTION__))
;
2044 assert(isSCEVable(Ty) &&(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2045, __extension__ __PRETTY_FUNCTION__))
2045 "This is not a conversion to a SCEVable type!")(static_cast <bool> (isSCEVable(Ty) && "This is not a conversion to a SCEVable type!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"This is not a conversion to a SCEVable type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2045, __extension__ __PRETTY_FUNCTION__))
;
2046 Ty = getEffectiveSCEVType(Ty);
2047
2048 // Sign-extend negative constants.
2049 if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
2050 if (SC->getAPInt().isNegative())
2051 return getSignExtendExpr(Op, Ty);
2052
2053 // Peel off a truncate cast.
2054 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
2055 const SCEV *NewOp = T->getOperand();
2056 if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
2057 return getAnyExtendExpr(NewOp, Ty);
2058 return getTruncateOrNoop(NewOp, Ty);
2059 }
2060
2061 // Next try a zext cast. If the cast is folded, use it.
2062 const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
2063 if (!isa<SCEVZeroExtendExpr>(ZExt))
2064 return ZExt;
2065
2066 // Next try a sext cast. If the cast is folded, use it.
2067 const SCEV *SExt = getSignExtendExpr(Op, Ty);
2068 if (!isa<SCEVSignExtendExpr>(SExt))
2069 return SExt;
2070
2071 // Force the cast to be folded into the operands of an addrec.
2072 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
2073 SmallVector<const SCEV *, 4> Ops;
2074 for (const SCEV *Op : AR->operands())
2075 Ops.push_back(getAnyExtendExpr(Op, Ty));
2076 return getAddRecExpr(Ops, AR->getLoop(), SCEV::FlagNW);
2077 }
2078
2079 // If the expression is obviously signed, use the sext cast value.
2080 if (isa<SCEVSMaxExpr>(Op))
2081 return SExt;
2082
2083 // Absent any other information, use the zext cast value.
2084 return ZExt;
2085}
2086
2087/// Process the given Ops list, which is a list of operands to be added under
2088/// the given scale, update the given map. This is a helper function for
2089/// getAddRecExpr. As an example of what it does, given a sequence of operands
2090/// that would form an add expression like this:
2091///
2092/// m + n + 13 + (A * (o + p + (B * (q + m + 29)))) + r + (-1 * r)
2093///
2094/// where A and B are constants, update the map with these values:
2095///
2096/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
2097///
2098/// and add 13 + A*B*29 to AccumulatedConstant.
2099/// This will allow getAddRecExpr to produce this:
2100///
2101/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
2102///
2103/// This form often exposes folding opportunities that are hidden in
2104/// the original operand list.
2105///
2106/// Return true iff it appears that any interesting folding opportunities
2107/// may be exposed. This helps getAddRecExpr short-circuit extra work in
2108/// the common case where no interesting opportunities are present, and
2109/// is also used as a check to avoid infinite recursion.
2110static bool
2111CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
2112 SmallVectorImpl<const SCEV *> &NewOps,
2113 APInt &AccumulatedConstant,
2114 const SCEV *const *Ops, size_t NumOperands,
2115 const APInt &Scale,
2116 ScalarEvolution &SE) {
2117 bool Interesting = false;
2118
2119 // Iterate over the add operands. They are sorted, with constants first.
2120 unsigned i = 0;
2121 while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2122 ++i;
2123 // Pull a buried constant out to the outside.
2124 if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
2125 Interesting = true;
2126 AccumulatedConstant += Scale * C->getAPInt();
2127 }
2128
2129 // Next comes everything else. We're especially interested in multiplies
2130 // here, but they're in the middle, so just visit the rest with one loop.
2131 for (; i != NumOperands; ++i) {
2132 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
2133 if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
2134 APInt NewScale =
2135 Scale * cast<SCEVConstant>(Mul->getOperand(0))->getAPInt();
2136 if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
2137 // A multiplication of a constant with another add; recurse.
2138 const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
2139 Interesting |=
2140 CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2141 Add->op_begin(), Add->getNumOperands(),
2142 NewScale, SE);
2143 } else {
2144 // A multiplication of a constant with some other value. Update
2145 // the map.
2146 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end());
2147 const SCEV *Key = SE.getMulExpr(MulOps);
2148 auto Pair = M.insert({Key, NewScale});
2149 if (Pair.second) {
2150 NewOps.push_back(Pair.first->first);
2151 } else {
2152 Pair.first->second += NewScale;
2153 // The map already had an entry for this value, which may indicate
2154 // a folding opportunity.
2155 Interesting = true;
2156 }
2157 }
2158 } else {
2159 // An ordinary operand. Update the map.
2160 std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
2161 M.insert({Ops[i], Scale});
2162 if (Pair.second) {
2163 NewOps.push_back(Pair.first->first);
2164 } else {
2165 Pair.first->second += Scale;
2166 // The map already had an entry for this value, which may indicate
2167 // a folding opportunity.
2168 Interesting = true;
2169 }
2170 }
2171 }
2172
2173 return Interesting;
2174}
2175
2176// We're trying to construct a SCEV of type `Type' with `Ops' as operands and
2177// `OldFlags' as can't-wrap behavior. Infer a more aggressive set of
2178// can't-overflow flags for the operation if possible.
2179static SCEV::NoWrapFlags
2180StrengthenNoWrapFlags(ScalarEvolution *SE, SCEVTypes Type,
2181 const SmallVectorImpl<const SCEV *> &Ops,
2182 SCEV::NoWrapFlags Flags) {
2183 using namespace std::placeholders;
2184
2185 using OBO = OverflowingBinaryOperator;
2186
2187 bool CanAnalyze =
2188 Type == scAddExpr || Type == scAddRecExpr || Type == scMulExpr;
2189 (void)CanAnalyze;
2190 assert(CanAnalyze && "don't call from other places!")(static_cast <bool> (CanAnalyze && "don't call from other places!"
) ? void (0) : __assert_fail ("CanAnalyze && \"don't call from other places!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2190, __extension__ __PRETTY_FUNCTION__))
;
2191
2192 int SignOrUnsignMask = SCEV::FlagNUW | SCEV::FlagNSW;
2193 SCEV::NoWrapFlags SignOrUnsignWrap =
2194 ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2195
2196 // If FlagNSW is true and all the operands are non-negative, infer FlagNUW.
2197 auto IsKnownNonNegative = [&](const SCEV *S) {
2198 return SE->isKnownNonNegative(S);
2199 };
2200
2201 if (SignOrUnsignWrap == SCEV::FlagNSW && all_of(Ops, IsKnownNonNegative))
2202 Flags =
2203 ScalarEvolution::setFlags(Flags, (SCEV::NoWrapFlags)SignOrUnsignMask);
2204
2205 SignOrUnsignWrap = ScalarEvolution::maskFlags(Flags, SignOrUnsignMask);
2206
2207 if (SignOrUnsignWrap != SignOrUnsignMask && Type == scAddExpr &&
2208 Ops.size() == 2 && isa<SCEVConstant>(Ops[0])) {
2209
2210 // (A + C) --> (A + C)<nsw> if the addition does not sign overflow
2211 // (A + C) --> (A + C)<nuw> if the addition does not unsign overflow
2212
2213 const APInt &C = cast<SCEVConstant>(Ops[0])->getAPInt();
2214 if (!(SignOrUnsignWrap & SCEV::FlagNSW)) {
2215 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2216 Instruction::Add, C, OBO::NoSignedWrap);
2217 if (NSWRegion.contains(SE->getSignedRange(Ops[1])))
2218 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNSW);
2219 }
2220 if (!(SignOrUnsignWrap & SCEV::FlagNUW)) {
2221 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
2222 Instruction::Add, C, OBO::NoUnsignedWrap);
2223 if (NUWRegion.contains(SE->getUnsignedRange(Ops[1])))
2224 Flags = ScalarEvolution::setFlags(Flags, SCEV::FlagNUW);
2225 }
2226 }
2227
2228 return Flags;
2229}
2230
2231bool ScalarEvolution::isAvailableAtLoopEntry(const SCEV *S, const Loop *L) {
2232 return isLoopInvariant(S, L) && properlyDominates(S, L->getHeader());
2233}
2234
2235/// Get a canonical add expression, or something simpler if possible.
2236const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2237 SCEV::NoWrapFlags Flags,
2238 unsigned Depth) {
2239 assert(!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) &&(static_cast <bool> (!(Flags & ~(SCEV::FlagNUW | SCEV
::FlagNSW)) && "only nuw or nsw allowed") ? void (0) :
__assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2240, __extension__ __PRETTY_FUNCTION__))
2240 "only nuw or nsw allowed")(static_cast <bool> (!(Flags & ~(SCEV::FlagNUW | SCEV
::FlagNSW)) && "only nuw or nsw allowed") ? void (0) :
__assert_fail ("!(Flags & ~(SCEV::FlagNUW | SCEV::FlagNSW)) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2240, __extension__ __PRETTY_FUNCTION__))
;
2241 assert(!Ops.empty() && "Cannot get empty add!")(static_cast <bool> (!Ops.empty() && "Cannot get empty add!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty add!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2241, __extension__ __PRETTY_FUNCTION__))
;
2242 if (Ops.size() == 1) return Ops[0];
2243#ifndef NDEBUG
2244 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2245 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2246 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "SCEVAddExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2247, __extension__ __PRETTY_FUNCTION__))
2247 "SCEVAddExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "SCEVAddExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVAddExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2247, __extension__ __PRETTY_FUNCTION__))
;
2248#endif
2249
2250 // Sort by complexity, this groups all similar expression types together.
2251 GroupByComplexity(Ops, &LI, DT);
2252
2253 Flags = StrengthenNoWrapFlags(this, scAddExpr, Ops, Flags);
2254
2255 // If there are any constants, fold them together.
2256 unsigned Idx = 0;
2257 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2258 ++Idx;
2259 assert(Idx < Ops.size())(static_cast <bool> (Idx < Ops.size()) ? void (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2259, __extension__ __PRETTY_FUNCTION__))
;
2260 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2261 // We found two constants, fold them together!
2262 Ops[0] = getConstant(LHSC->getAPInt() + RHSC->getAPInt());
2263 if (Ops.size() == 2) return Ops[0];
2264 Ops.erase(Ops.begin()+1); // Erase the folded element
2265 LHSC = cast<SCEVConstant>(Ops[0]);
2266 }
2267
2268 // If we are left with a constant zero being added, strip it off.
2269 if (LHSC->getValue()->isZero()) {
2270 Ops.erase(Ops.begin());
2271 --Idx;
2272 }
2273
2274 if (Ops.size() == 1) return Ops[0];
2275 }
2276
2277 // Limit recursion calls depth.
2278 if (Depth > MaxArithDepth)
2279 return getOrCreateAddExpr(Ops, Flags);
2280
2281 // Okay, check to see if the same value occurs in the operand list more than
2282 // once. If so, merge them together into an multiply expression. Since we
2283 // sorted the list, these values are required to be adjacent.
2284 Type *Ty = Ops[0]->getType();
2285 bool FoundMatch = false;
2286 for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
2287 if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
2288 // Scan ahead to count how many equal operands there are.
2289 unsigned Count = 2;
2290 while (i+Count != e && Ops[i+Count] == Ops[i])
2291 ++Count;
2292 // Merge the values into a multiply.
2293 const SCEV *Scale = getConstant(Ty, Count);
2294 const SCEV *Mul = getMulExpr(Scale, Ops[i], SCEV::FlagAnyWrap, Depth + 1);
2295 if (Ops.size() == Count)
2296 return Mul;
2297 Ops[i] = Mul;
2298 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
2299 --i; e -= Count - 1;
2300 FoundMatch = true;
2301 }
2302 if (FoundMatch)
2303 return getAddExpr(Ops, Flags, Depth + 1);
2304
2305 // Check for truncates. If all the operands are truncated from the same
2306 // type, see if factoring out the truncate would permit the result to be
2307 // folded. eg., n*trunc(x) + m*trunc(y) --> trunc(trunc(m)*x + trunc(n)*y)
2308 // if the contents of the resulting outer trunc fold to something simple.
2309 auto FindTruncSrcType = [&]() -> Type * {
2310 // We're ultimately looking to fold an addrec of truncs and muls of only
2311 // constants and truncs, so if we find any other types of SCEV
2312 // as operands of the addrec then we bail and return nullptr here.
2313 // Otherwise, we return the type of the operand of a trunc that we find.
2314 if (auto *T = dyn_cast<SCEVTruncateExpr>(Ops[Idx]))
2315 return T->getOperand()->getType();
2316 if (const auto *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2317 const auto *LastOp = Mul->getOperand(Mul->getNumOperands() - 1);
2318 if (const auto *T = dyn_cast<SCEVTruncateExpr>(LastOp))
2319 return T->getOperand()->getType();
2320 }
2321 return nullptr;
2322 };
2323 if (auto *SrcType = FindTruncSrcType()) {
2324 SmallVector<const SCEV *, 8> LargeOps;
2325 bool Ok = true;
2326 // Check all the operands to see if they can be represented in the
2327 // source type of the truncate.
2328 for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
2329 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
2330 if (T->getOperand()->getType() != SrcType) {
2331 Ok = false;
2332 break;
2333 }
2334 LargeOps.push_back(T->getOperand());
2335 } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
2336 LargeOps.push_back(getAnyExtendExpr(C, SrcType));
2337 } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
2338 SmallVector<const SCEV *, 8> LargeMulOps;
2339 for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
2340 if (const SCEVTruncateExpr *T =
2341 dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
2342 if (T->getOperand()->getType() != SrcType) {
2343 Ok = false;
2344 break;
2345 }
2346 LargeMulOps.push_back(T->getOperand());
2347 } else if (const auto *C = dyn_cast<SCEVConstant>(M->getOperand(j))) {
2348 LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
2349 } else {
2350 Ok = false;
2351 break;
2352 }
2353 }
2354 if (Ok)
2355 LargeOps.push_back(getMulExpr(LargeMulOps, SCEV::FlagAnyWrap, Depth + 1));
2356 } else {
2357 Ok = false;
2358 break;
2359 }
2360 }
2361 if (Ok) {
2362 // Evaluate the expression in the larger type.
2363 const SCEV *Fold = getAddExpr(LargeOps, Flags, Depth + 1);
2364 // If it folds to something simple, use it. Otherwise, don't.
2365 if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
2366 return getTruncateExpr(Fold, Ty);
2367 }
2368 }
2369
2370 // Skip past any other cast SCEVs.
2371 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
2372 ++Idx;
2373
2374 // If there are add operands they would be next.
2375 if (Idx < Ops.size()) {
2376 bool DeletedAdd = false;
2377 while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
2378 if (Ops.size() > AddOpsInlineThreshold ||
2379 Add->getNumOperands() > AddOpsInlineThreshold)
2380 break;
2381 // If we have an add, expand the add operands onto the end of the operands
2382 // list.
2383 Ops.erase(Ops.begin()+Idx);
2384 Ops.append(Add->op_begin(), Add->op_end());
2385 DeletedAdd = true;
2386 }
2387
2388 // If we deleted at least one add, we added operands to the end of the list,
2389 // and they are not necessarily sorted. Recurse to resort and resimplify
2390 // any operands we just acquired.
2391 if (DeletedAdd)
2392 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2393 }
2394
2395 // Skip over the add expression until we get to a multiply.
2396 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2397 ++Idx;
2398
2399 // Check to see if there are any folding opportunities present with
2400 // operands multiplied by constant values.
2401 if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
2402 uint64_t BitWidth = getTypeSizeInBits(Ty);
2403 DenseMap<const SCEV *, APInt> M;
2404 SmallVector<const SCEV *, 8> NewOps;
2405 APInt AccumulatedConstant(BitWidth, 0);
2406 if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
2407 Ops.data(), Ops.size(),
2408 APInt(BitWidth, 1), *this)) {
2409 struct APIntCompare {
2410 bool operator()(const APInt &LHS, const APInt &RHS) const {
2411 return LHS.ult(RHS);
2412 }
2413 };
2414
2415 // Some interesting folding opportunity is present, so its worthwhile to
2416 // re-generate the operands list. Group the operands by constant scale,
2417 // to avoid multiplying by the same constant scale multiple times.
2418 std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
2419 for (const SCEV *NewOp : NewOps)
2420 MulOpLists[M.find(NewOp)->second].push_back(NewOp);
2421 // Re-generate the operands list.
2422 Ops.clear();
2423 if (AccumulatedConstant != 0)
2424 Ops.push_back(getConstant(AccumulatedConstant));
2425 for (auto &MulOp : MulOpLists)
2426 if (MulOp.first != 0)
2427 Ops.push_back(getMulExpr(
2428 getConstant(MulOp.first),
2429 getAddExpr(MulOp.second, SCEV::FlagAnyWrap, Depth + 1),
2430 SCEV::FlagAnyWrap, Depth + 1));
2431 if (Ops.empty())
2432 return getZero(Ty);
2433 if (Ops.size() == 1)
2434 return Ops[0];
2435 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2436 }
2437 }
2438
2439 // If we are adding something to a multiply expression, make sure the
2440 // something is not already an operand of the multiply. If so, merge it into
2441 // the multiply.
2442 for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
2443 const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
2444 for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
2445 const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
2446 if (isa<SCEVConstant>(MulOpSCEV))
2447 continue;
2448 for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
2449 if (MulOpSCEV == Ops[AddOp]) {
2450 // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
2451 const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
2452 if (Mul->getNumOperands() != 2) {
2453 // If the multiply has more than two operands, we must get the
2454 // Y*Z term.
2455 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2456 Mul->op_begin()+MulOp);
2457 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2458 InnerMul = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2459 }
2460 SmallVector<const SCEV *, 2> TwoOps = {getOne(Ty), InnerMul};
2461 const SCEV *AddOne = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2462 const SCEV *OuterMul = getMulExpr(AddOne, MulOpSCEV,
2463 SCEV::FlagAnyWrap, Depth + 1);
2464 if (Ops.size() == 2) return OuterMul;
2465 if (AddOp < Idx) {
2466 Ops.erase(Ops.begin()+AddOp);
2467 Ops.erase(Ops.begin()+Idx-1);
2468 } else {
2469 Ops.erase(Ops.begin()+Idx);
2470 Ops.erase(Ops.begin()+AddOp-1);
2471 }
2472 Ops.push_back(OuterMul);
2473 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2474 }
2475
2476 // Check this multiply against other multiplies being added together.
2477 for (unsigned OtherMulIdx = Idx+1;
2478 OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
2479 ++OtherMulIdx) {
2480 const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
2481 // If MulOp occurs in OtherMul, we can fold the two multiplies
2482 // together.
2483 for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
2484 OMulOp != e; ++OMulOp)
2485 if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
2486 // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
2487 const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
2488 if (Mul->getNumOperands() != 2) {
2489 SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
2490 Mul->op_begin()+MulOp);
2491 MulOps.append(Mul->op_begin()+MulOp+1, Mul->op_end());
2492 InnerMul1 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2493 }
2494 const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
2495 if (OtherMul->getNumOperands() != 2) {
2496 SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
2497 OtherMul->op_begin()+OMulOp);
2498 MulOps.append(OtherMul->op_begin()+OMulOp+1, OtherMul->op_end());
2499 InnerMul2 = getMulExpr(MulOps, SCEV::FlagAnyWrap, Depth + 1);
2500 }
2501 SmallVector<const SCEV *, 2> TwoOps = {InnerMul1, InnerMul2};
2502 const SCEV *InnerMulSum =
2503 getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2504 const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum,
2505 SCEV::FlagAnyWrap, Depth + 1);
2506 if (Ops.size() == 2) return OuterMul;
2507 Ops.erase(Ops.begin()+Idx);
2508 Ops.erase(Ops.begin()+OtherMulIdx-1);
2509 Ops.push_back(OuterMul);
2510 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2511 }
2512 }
2513 }
2514 }
2515
2516 // If there are any add recurrences in the operands list, see if any other
2517 // added values are loop invariant. If so, we can fold them into the
2518 // recurrence.
2519 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2520 ++Idx;
2521
2522 // Scan over all recurrences, trying to fold loop invariants into them.
2523 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2524 // Scan all of the other operands to this add and add them to the vector if
2525 // they are loop invariant w.r.t. the recurrence.
2526 SmallVector<const SCEV *, 8> LIOps;
2527 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2528 const Loop *AddRecLoop = AddRec->getLoop();
2529 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2530 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2531 LIOps.push_back(Ops[i]);
2532 Ops.erase(Ops.begin()+i);
2533 --i; --e;
2534 }
2535
2536 // If we found some loop invariants, fold them into the recurrence.
2537 if (!LIOps.empty()) {
2538 // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
2539 LIOps.push_back(AddRec->getStart());
2540
2541 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2542 AddRec->op_end());
2543 // This follows from the fact that the no-wrap flags on the outer add
2544 // expression are applicable on the 0th iteration, when the add recurrence
2545 // will be equal to its start value.
2546 AddRecOps[0] = getAddExpr(LIOps, Flags, Depth + 1);
2547
2548 // Build the new addrec. Propagate the NUW and NSW flags if both the
2549 // outer add and the inner addrec are guaranteed to have no overflow.
2550 // Always propagate NW.
2551 Flags = AddRec->getNoWrapFlags(setFlags(Flags, SCEV::FlagNW));
2552 const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop, Flags);
2553
2554 // If all of the other operands were loop invariant, we are done.
2555 if (Ops.size() == 1) return NewRec;
2556
2557 // Otherwise, add the folded AddRec by the non-invariant parts.
2558 for (unsigned i = 0;; ++i)
2559 if (Ops[i] == AddRec) {
2560 Ops[i] = NewRec;
2561 break;
2562 }
2563 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2564 }
2565
2566 // Okay, if there weren't any loop invariants to be folded, check to see if
2567 // there are multiple AddRec's with the same loop induction variable being
2568 // added together. If so, we can fold them.
2569 for (unsigned OtherIdx = Idx+1;
2570 OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2571 ++OtherIdx) {
2572 // We expect the AddRecExpr's to be sorted in reverse dominance order,
2573 // so that the 1st found AddRecExpr is dominated by all others.
2574 assert(DT.dominates((static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr
>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->
getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2577, __extension__ __PRETTY_FUNCTION__))
2575 cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()->getHeader(),(static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr
>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->
getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2577, __extension__ __PRETTY_FUNCTION__))
2576 AddRec->getLoop()->getHeader()) &&(static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr
>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->
getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2577, __extension__ __PRETTY_FUNCTION__))
2577 "AddRecExprs are not sorted in reverse dominance order?")(static_cast <bool> (DT.dominates( cast<SCEVAddRecExpr
>(Ops[OtherIdx])->getLoop()->getHeader(), AddRec->
getLoop()->getHeader()) && "AddRecExprs are not sorted in reverse dominance order?"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2577, __extension__ __PRETTY_FUNCTION__))
;
2578 if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
2579 // Other + {A,+,B}<L> + {C,+,D}<L> --> Other + {A+C,+,B+D}<L>
2580 SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
2581 AddRec->op_end());
2582 for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2583 ++OtherIdx) {
2584 const auto *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2585 if (OtherAddRec->getLoop() == AddRecLoop) {
2586 for (unsigned i = 0, e = OtherAddRec->getNumOperands();
2587 i != e; ++i) {
2588 if (i >= AddRecOps.size()) {
2589 AddRecOps.append(OtherAddRec->op_begin()+i,
2590 OtherAddRec->op_end());
2591 break;
2592 }
2593 SmallVector<const SCEV *, 2> TwoOps = {
2594 AddRecOps[i], OtherAddRec->getOperand(i)};
2595 AddRecOps[i] = getAddExpr(TwoOps, SCEV::FlagAnyWrap, Depth + 1);
2596 }
2597 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2598 }
2599 }
2600 // Step size has changed, so we cannot guarantee no self-wraparound.
2601 Ops[Idx] = getAddRecExpr(AddRecOps, AddRecLoop, SCEV::FlagAnyWrap);
2602 return getAddExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2603 }
2604 }
2605
2606 // Otherwise couldn't fold anything into this recurrence. Move onto the
2607 // next one.
2608 }
2609
2610 // Okay, it looks like we really DO need an add expr. Check to see if we
2611 // already have one, otherwise create a new one.
2612 return getOrCreateAddExpr(Ops, Flags);
2613}
2614
2615const SCEV *
2616ScalarEvolution::getOrCreateAddExpr(SmallVectorImpl<const SCEV *> &Ops,
2617 SCEV::NoWrapFlags Flags) {
2618 FoldingSetNodeID ID;
2619 ID.AddInteger(scAddExpr);
2620 for (const SCEV *Op : Ops)
2621 ID.AddPointer(Op);
2622 void *IP = nullptr;
2623 SCEVAddExpr *S =
2624 static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2625 if (!S) {
2626 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2627 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2628 S = new (SCEVAllocator)
2629 SCEVAddExpr(ID.Intern(SCEVAllocator), O, Ops.size());
2630 UniqueSCEVs.InsertNode(S, IP);
2631 addToLoopUseLists(S);
2632 }
2633 S->setNoWrapFlags(Flags);
2634 return S;
2635}
2636
2637const SCEV *
2638ScalarEvolution::getOrCreateMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2639 SCEV::NoWrapFlags Flags) {
2640 FoldingSetNodeID ID;
2641 ID.AddInteger(scMulExpr);
2642 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2643 ID.AddPointer(Ops[i]);
2644 void *IP = nullptr;
2645 SCEVMulExpr *S =
2646 static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
2647 if (!S) {
2648 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
2649 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
2650 S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
2651 O, Ops.size());
2652 UniqueSCEVs.InsertNode(S, IP);
2653 addToLoopUseLists(S);
2654 }
2655 S->setNoWrapFlags(Flags);
2656 return S;
2657}
2658
2659static uint64_t umul_ov(uint64_t i, uint64_t j, bool &Overflow) {
2660 uint64_t k = i*j;
2661 if (j > 1 && k / j != i) Overflow = true;
2662 return k;
2663}
2664
2665/// Compute the result of "n choose k", the binomial coefficient. If an
2666/// intermediate computation overflows, Overflow will be set and the return will
2667/// be garbage. Overflow is not cleared on absence of overflow.
2668static uint64_t Choose(uint64_t n, uint64_t k, bool &Overflow) {
2669 // We use the multiplicative formula:
2670 // n(n-1)(n-2)...(n-(k-1)) / k(k-1)(k-2)...1 .
2671 // At each iteration, we take the n-th term of the numeral and divide by the
2672 // (k-n)th term of the denominator. This division will always produce an
2673 // integral result, and helps reduce the chance of overflow in the
2674 // intermediate computations. However, we can still overflow even when the
2675 // final result would fit.
2676
2677 if (n == 0 || n == k) return 1;
2678 if (k > n) return 0;
2679
2680 if (k > n/2)
2681 k = n-k;
2682
2683 uint64_t r = 1;
2684 for (uint64_t i = 1; i <= k; ++i) {
2685 r = umul_ov(r, n-(i-1), Overflow);
2686 r /= i;
2687 }
2688 return r;
2689}
2690
2691/// Determine if any of the operands in this SCEV are a constant or if
2692/// any of the add or multiply expressions in this SCEV contain a constant.
2693static bool containsConstantInAddMulChain(const SCEV *StartExpr) {
2694 struct FindConstantInAddMulChain {
2695 bool FoundConstant = false;
2696
2697 bool follow(const SCEV *S) {
2698 FoundConstant |= isa<SCEVConstant>(S);
2699 return isa<SCEVAddExpr>(S) || isa<SCEVMulExpr>(S);
2700 }
2701
2702 bool isDone() const {
2703 return FoundConstant;
2704 }
2705 };
2706
2707 FindConstantInAddMulChain F;
2708 SCEVTraversal<FindConstantInAddMulChain> ST(F);
2709 ST.visitAll(StartExpr);
2710 return F.FoundConstant;
2711}
2712
2713/// Get a canonical multiply expression, or something simpler if possible.
2714const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
2715 SCEV::NoWrapFlags Flags,
2716 unsigned Depth) {
2717 assert(Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) &&(static_cast <bool> (Flags == maskFlags(Flags, SCEV::FlagNUW
| SCEV::FlagNSW) && "only nuw or nsw allowed") ? void
(0) : __assert_fail ("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2718, __extension__ __PRETTY_FUNCTION__))
2718 "only nuw or nsw allowed")(static_cast <bool> (Flags == maskFlags(Flags, SCEV::FlagNUW
| SCEV::FlagNSW) && "only nuw or nsw allowed") ? void
(0) : __assert_fail ("Flags == maskFlags(Flags, SCEV::FlagNUW | SCEV::FlagNSW) && \"only nuw or nsw allowed\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2718, __extension__ __PRETTY_FUNCTION__))
;
2719 assert(!Ops.empty() && "Cannot get empty mul!")(static_cast <bool> (!Ops.empty() && "Cannot get empty mul!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty mul!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2719, __extension__ __PRETTY_FUNCTION__))
;
2720 if (Ops.size() == 1) return Ops[0];
2721#ifndef NDEBUG
2722 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
2723 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
2724 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "SCEVMulExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2725, __extension__ __PRETTY_FUNCTION__))
2725 "SCEVMulExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "SCEVMulExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVMulExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2725, __extension__ __PRETTY_FUNCTION__))
;
2726#endif
2727
2728 // Sort by complexity, this groups all similar expression types together.
2729 GroupByComplexity(Ops, &LI, DT);
2730
2731 Flags = StrengthenNoWrapFlags(this, scMulExpr, Ops, Flags);
2732
2733 // Limit recursion calls depth.
2734 if (Depth > MaxArithDepth)
2735 return getOrCreateMulExpr(Ops, Flags);
2736
2737 // If there are any constants, fold them together.
2738 unsigned Idx = 0;
2739 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
2740
2741 // C1*(C2+V) -> C1*C2 + C1*V
2742 if (Ops.size() == 2)
2743 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
2744 // If any of Add's ops are Adds or Muls with a constant,
2745 // apply this transformation as well.
2746 if (Add->getNumOperands() == 2)
2747 // TODO: There are some cases where this transformation is not
2748 // profitable, for example:
2749 // Add = (C0 + X) * Y + Z.
2750 // Maybe the scope of this transformation should be narrowed down.
2751 if (containsConstantInAddMulChain(Add))
2752 return getAddExpr(getMulExpr(LHSC, Add->getOperand(0),
2753 SCEV::FlagAnyWrap, Depth + 1),
2754 getMulExpr(LHSC, Add->getOperand(1),
2755 SCEV::FlagAnyWrap, Depth + 1),
2756 SCEV::FlagAnyWrap, Depth + 1);
2757
2758 ++Idx;
2759 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
2760 // We found two constants, fold them together!
2761 ConstantInt *Fold =
2762 ConstantInt::get(getContext(), LHSC->getAPInt() * RHSC->getAPInt());
2763 Ops[0] = getConstant(Fold);
2764 Ops.erase(Ops.begin()+1); // Erase the folded element
2765 if (Ops.size() == 1) return Ops[0];
2766 LHSC = cast<SCEVConstant>(Ops[0]);
2767 }
2768
2769 // If we are left with a constant one being multiplied, strip it off.
2770 if (cast<SCEVConstant>(Ops[0])->getValue()->isOne()) {
2771 Ops.erase(Ops.begin());
2772 --Idx;
2773 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
2774 // If we have a multiply of zero, it will always be zero.
2775 return Ops[0];
2776 } else if (Ops[0]->isAllOnesValue()) {
2777 // If we have a mul by -1 of an add, try distributing the -1 among the
2778 // add operands.
2779 if (Ops.size() == 2) {
2780 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
2781 SmallVector<const SCEV *, 4> NewOps;
2782 bool AnyFolded = false;
2783 for (const SCEV *AddOp : Add->operands()) {
2784 const SCEV *Mul = getMulExpr(Ops[0], AddOp, SCEV::FlagAnyWrap,
2785 Depth + 1);
2786 if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
2787 NewOps.push_back(Mul);
2788 }
2789 if (AnyFolded)
2790 return getAddExpr(NewOps, SCEV::FlagAnyWrap, Depth + 1);
2791 } else if (const auto *AddRec = dyn_cast<SCEVAddRecExpr>(Ops[1])) {
2792 // Negation preserves a recurrence's no self-wrap property.
2793 SmallVector<const SCEV *, 4> Operands;
2794 for (const SCEV *AddRecOp : AddRec->operands())
2795 Operands.push_back(getMulExpr(Ops[0], AddRecOp, SCEV::FlagAnyWrap,
2796 Depth + 1));
2797
2798 return getAddRecExpr(Operands, AddRec->getLoop(),
2799 AddRec->getNoWrapFlags(SCEV::FlagNW));
2800 }
2801 }
2802 }
2803
2804 if (Ops.size() == 1)
2805 return Ops[0];
2806 }
2807
2808 // Skip over the add expression until we get to a multiply.
2809 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
2810 ++Idx;
2811
2812 // If there are mul operands inline them all into this expression.
2813 if (Idx < Ops.size()) {
2814 bool DeletedMul = false;
2815 while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
2816 if (Ops.size() > MulOpsInlineThreshold)
2817 break;
2818 // If we have an mul, expand the mul operands onto the end of the
2819 // operands list.
2820 Ops.erase(Ops.begin()+Idx);
2821 Ops.append(Mul->op_begin(), Mul->op_end());
2822 DeletedMul = true;
2823 }
2824
2825 // If we deleted at least one mul, we added operands to the end of the
2826 // list, and they are not necessarily sorted. Recurse to resort and
2827 // resimplify any operands we just acquired.
2828 if (DeletedMul)
2829 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2830 }
2831
2832 // If there are any add recurrences in the operands list, see if any other
2833 // added values are loop invariant. If so, we can fold them into the
2834 // recurrence.
2835 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
2836 ++Idx;
2837
2838 // Scan over all recurrences, trying to fold loop invariants into them.
2839 for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
2840 // Scan all of the other operands to this mul and add them to the vector
2841 // if they are loop invariant w.r.t. the recurrence.
2842 SmallVector<const SCEV *, 8> LIOps;
2843 const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
2844 const Loop *AddRecLoop = AddRec->getLoop();
2845 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
2846 if (isAvailableAtLoopEntry(Ops[i], AddRecLoop)) {
2847 LIOps.push_back(Ops[i]);
2848 Ops.erase(Ops.begin()+i);
2849 --i; --e;
2850 }
2851
2852 // If we found some loop invariants, fold them into the recurrence.
2853 if (!LIOps.empty()) {
2854 // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
2855 SmallVector<const SCEV *, 4> NewOps;
2856 NewOps.reserve(AddRec->getNumOperands());
2857 const SCEV *Scale = getMulExpr(LIOps, SCEV::FlagAnyWrap, Depth + 1);
2858 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
2859 NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i),
2860 SCEV::FlagAnyWrap, Depth + 1));
2861
2862 // Build the new addrec. Propagate the NUW and NSW flags if both the
2863 // outer mul and the inner addrec are guaranteed to have no overflow.
2864 //
2865 // No self-wrap cannot be guaranteed after changing the step size, but
2866 // will be inferred if either NUW or NSW is true.
2867 Flags = AddRec->getNoWrapFlags(clearFlags(Flags, SCEV::FlagNW));
2868 const SCEV *NewRec = getAddRecExpr(NewOps, AddRecLoop, Flags);
2869
2870 // If all of the other operands were loop invariant, we are done.
2871 if (Ops.size() == 1) return NewRec;
2872
2873 // Otherwise, multiply the folded AddRec by the non-invariant parts.
2874 for (unsigned i = 0;; ++i)
2875 if (Ops[i] == AddRec) {
2876 Ops[i] = NewRec;
2877 break;
2878 }
2879 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2880 }
2881
2882 // Okay, if there weren't any loop invariants to be folded, check to see
2883 // if there are multiple AddRec's with the same loop induction variable
2884 // being multiplied together. If so, we can fold them.
2885
2886 // {A1,+,A2,+,...,+,An}<L> * {B1,+,B2,+,...,+,Bn}<L>
2887 // = {x=1 in [ sum y=x..2x [ sum z=max(y-x, y-n)..min(x,n) [
2888 // choose(x, 2x)*choose(2x-y, x-z)*A_{y-z}*B_z
2889 // ]]],+,...up to x=2n}.
2890 // Note that the arguments to choose() are always integers with values
2891 // known at compile time, never SCEV objects.
2892 //
2893 // The implementation avoids pointless extra computations when the two
2894 // addrec's are of different length (mathematically, it's equivalent to
2895 // an infinite stream of zeros on the right).
2896 bool OpsModified = false;
2897 for (unsigned OtherIdx = Idx+1;
2898 OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
2899 ++OtherIdx) {
2900 const SCEVAddRecExpr *OtherAddRec =
2901 dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]);
2902 if (!OtherAddRec || OtherAddRec->getLoop() != AddRecLoop)
2903 continue;
2904
2905 // Limit max number of arguments to avoid creation of unreasonably big
2906 // SCEVAddRecs with very complex operands.
2907 if (AddRec->getNumOperands() + OtherAddRec->getNumOperands() - 1 >
2908 MaxAddRecSize)
2909 continue;
2910
2911 bool Overflow = false;
2912 Type *Ty = AddRec->getType();
2913 bool LargerThan64Bits = getTypeSizeInBits(Ty) > 64;
2914 SmallVector<const SCEV*, 7> AddRecOps;
2915 for (int x = 0, xe = AddRec->getNumOperands() +
2916 OtherAddRec->getNumOperands() - 1; x != xe && !Overflow; ++x) {
2917 const SCEV *Term = getZero(Ty);
2918 for (int y = x, ye = 2*x+1; y != ye && !Overflow; ++y) {
2919 uint64_t Coeff1 = Choose(x, 2*x - y, Overflow);
2920 for (int z = std::max(y-x, y-(int)AddRec->getNumOperands()+1),
2921 ze = std::min(x+1, (int)OtherAddRec->getNumOperands());
2922 z < ze && !Overflow; ++z) {
2923 uint64_t Coeff2 = Choose(2*x - y, x-z, Overflow);
2924 uint64_t Coeff;
2925 if (LargerThan64Bits)
2926 Coeff = umul_ov(Coeff1, Coeff2, Overflow);
2927 else
2928 Coeff = Coeff1*Coeff2;
2929 const SCEV *CoeffTerm = getConstant(Ty, Coeff);
2930 const SCEV *Term1 = AddRec->getOperand(y-z);
2931 const SCEV *Term2 = OtherAddRec->getOperand(z);
2932 Term = getAddExpr(Term, getMulExpr(CoeffTerm, Term1, Term2,
2933 SCEV::FlagAnyWrap, Depth + 1),
2934 SCEV::FlagAnyWrap, Depth + 1);
2935 }
2936 }
2937 AddRecOps.push_back(Term);
2938 }
2939 if (!Overflow) {
2940 const SCEV *NewAddRec = getAddRecExpr(AddRecOps, AddRec->getLoop(),
2941 SCEV::FlagAnyWrap);
2942 if (Ops.size() == 2) return NewAddRec;
2943 Ops[Idx] = NewAddRec;
2944 Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
2945 OpsModified = true;
2946 AddRec = dyn_cast<SCEVAddRecExpr>(NewAddRec);
2947 if (!AddRec)
2948 break;
2949 }
2950 }
2951 if (OpsModified)
2952 return getMulExpr(Ops, SCEV::FlagAnyWrap, Depth + 1);
2953
2954 // Otherwise couldn't fold anything into this recurrence. Move onto the
2955 // next one.
2956 }
2957
2958 // Okay, it looks like we really DO need an mul expr. Check to see if we
2959 // already have one, otherwise create a new one.
2960 return getOrCreateMulExpr(Ops, Flags);
2961}
2962
2963/// Represents an unsigned remainder expression based on unsigned division.
2964const SCEV *ScalarEvolution::getURemExpr(const SCEV *LHS,
2965 const SCEV *RHS) {
2966 assert(getEffectiveSCEVType(LHS->getType()) ==(static_cast <bool> (getEffectiveSCEVType(LHS->getType
()) == getEffectiveSCEVType(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2968, __extension__ __PRETTY_FUNCTION__))
2967 getEffectiveSCEVType(RHS->getType()) &&(static_cast <bool> (getEffectiveSCEVType(LHS->getType
()) == getEffectiveSCEVType(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2968, __extension__ __PRETTY_FUNCTION__))
2968 "SCEVURemExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(LHS->getType
()) == getEffectiveSCEVType(RHS->getType()) && "SCEVURemExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVURemExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2968, __extension__ __PRETTY_FUNCTION__))
;
2969
2970 // Short-circuit easy cases
2971 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
2972 // If constant is one, the result is trivial
2973 if (RHSC->getValue()->isOne())
2974 return getZero(LHS->getType()); // X urem 1 --> 0
2975
2976 // If constant is a power of two, fold into a zext(trunc(LHS)).
2977 if (RHSC->getAPInt().isPowerOf2()) {
2978 Type *FullTy = LHS->getType();
2979 Type *TruncTy =
2980 IntegerType::get(getContext(), RHSC->getAPInt().logBase2());
2981 return getZeroExtendExpr(getTruncateExpr(LHS, TruncTy), FullTy);
2982 }
2983 }
2984
2985 // Fallback to %a == %x urem %y == %x -<nuw> ((%x udiv %y) *<nuw> %y)
2986 const SCEV *UDiv = getUDivExpr(LHS, RHS);
2987 const SCEV *Mult = getMulExpr(UDiv, RHS, SCEV::FlagNUW);
2988 return getMinusSCEV(LHS, Mult, SCEV::FlagNUW);
2989}
2990
2991/// Get a canonical unsigned division expression, or something simpler if
2992/// possible.
2993const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
2994 const SCEV *RHS) {
2995 assert(getEffectiveSCEVType(LHS->getType()) ==(static_cast <bool> (getEffectiveSCEVType(LHS->getType
()) == getEffectiveSCEVType(RHS->getType()) && "SCEVUDivExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2997, __extension__ __PRETTY_FUNCTION__))
2996 getEffectiveSCEVType(RHS->getType()) &&(static_cast <bool> (getEffectiveSCEVType(LHS->getType
()) == getEffectiveSCEVType(RHS->getType()) && "SCEVUDivExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2997, __extension__ __PRETTY_FUNCTION__))
2997 "SCEVUDivExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(LHS->getType
()) == getEffectiveSCEVType(RHS->getType()) && "SCEVUDivExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(LHS->getType()) == getEffectiveSCEVType(RHS->getType()) && \"SCEVUDivExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 2997, __extension__ __PRETTY_FUNCTION__))
;
2998
2999 if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
3000 if (RHSC->getValue()->isOne())
3001 return LHS; // X udiv 1 --> x
3002 // If the denominator is zero, the result of the udiv is undefined. Don't
3003 // try to analyze it, because the resolution chosen here may differ from
3004 // the resolution chosen in other parts of the compiler.
3005 if (!RHSC->getValue()->isZero()) {
3006 // Determine if the division can be folded into the operands of
3007 // its operands.
3008 // TODO: Generalize this to non-constants by using known-bits information.
3009 Type *Ty = LHS->getType();
3010 unsigned LZ = RHSC->getAPInt().countLeadingZeros();
3011 unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ - 1;
3012 // For non-power-of-two values, effectively round the value up to the
3013 // nearest power of two.
3014 if (!RHSC->getAPInt().isPowerOf2())
3015 ++MaxShiftAmt;
3016 IntegerType *ExtTy =
3017 IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
3018 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
3019 if (const SCEVConstant *Step =
3020 dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this))) {
3021 // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
3022 const APInt &StepInt = Step->getAPInt();
3023 const APInt &DivInt = RHSC->getAPInt();
3024 if (!StepInt.urem(DivInt) &&
3025 getZeroExtendExpr(AR, ExtTy) ==
3026 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3027 getZeroExtendExpr(Step, ExtTy),
3028 AR->getLoop(), SCEV::FlagAnyWrap)) {
3029 SmallVector<const SCEV *, 4> Operands;
3030 for (const SCEV *Op : AR->operands())
3031 Operands.push_back(getUDivExpr(Op, RHS));
3032 return getAddRecExpr(Operands, AR->getLoop(), SCEV::FlagNW);
3033 }
3034 /// Get a canonical UDivExpr for a recurrence.
3035 /// {X,+,N}/C => {Y,+,N}/C where Y=X-(X%N). Safe when C%N=0.
3036 // We can currently only fold X%N if X is constant.
3037 const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
3038 if (StartC && !DivInt.urem(StepInt) &&
3039 getZeroExtendExpr(AR, ExtTy) ==
3040 getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
3041 getZeroExtendExpr(Step, ExtTy),
3042 AR->getLoop(), SCEV::FlagAnyWrap)) {
3043 const APInt &StartInt = StartC->getAPInt();
3044 const APInt &StartRem = StartInt.urem(StepInt);
3045 if (StartRem != 0)
3046 LHS = getAddRecExpr(getConstant(StartInt - StartRem), Step,
3047 AR->getLoop(), SCEV::FlagNW);
3048 }
3049 }
3050 // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
3051 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
3052 SmallVector<const SCEV *, 4> Operands;
3053 for (const SCEV *Op : M->operands())
3054 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3055 if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
3056 // Find an operand that's safely divisible.
3057 for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
3058 const SCEV *Op = M->getOperand(i);
3059 const SCEV *Div = getUDivExpr(Op, RHSC);
3060 if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
3061 Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
3062 M->op_end());
3063 Operands[i] = Div;
3064 return getMulExpr(Operands);
3065 }
3066 }
3067 }
3068 // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
3069 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(LHS)) {
3070 SmallVector<const SCEV *, 4> Operands;
3071 for (const SCEV *Op : A->operands())
3072 Operands.push_back(getZeroExtendExpr(Op, ExtTy));
3073 if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
3074 Operands.clear();
3075 for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
3076 const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
3077 if (isa<SCEVUDivExpr>(Op) ||
3078 getMulExpr(Op, RHS) != A->getOperand(i))
3079 break;
3080 Operands.push_back(Op);
3081 }
3082 if (Operands.size() == A->getNumOperands())
3083 return getAddExpr(Operands);
3084 }
3085 }
3086
3087 // Fold if both operands are constant.
3088 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
3089 Constant *LHSCV = LHSC->getValue();
3090 Constant *RHSCV = RHSC->getValue();
3091 return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
3092 RHSCV)));
3093 }
3094 }
3095 }
3096
3097 FoldingSetNodeID ID;
3098 ID.AddInteger(scUDivExpr);
3099 ID.AddPointer(LHS);
3100 ID.AddPointer(RHS);
3101 void *IP = nullptr;
3102 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3103 SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
3104 LHS, RHS);
3105 UniqueSCEVs.InsertNode(S, IP);
3106 addToLoopUseLists(S);
3107 return S;
3108}
3109
3110static const APInt gcd(const SCEVConstant *C1, const SCEVConstant *C2) {
3111 APInt A = C1->getAPInt().abs();
3112 APInt B = C2->getAPInt().abs();
3113 uint32_t ABW = A.getBitWidth();
3114 uint32_t BBW = B.getBitWidth();
3115
3116 if (ABW > BBW)
3117 B = B.zext(ABW);
3118 else if (ABW < BBW)
3119 A = A.zext(BBW);
3120
3121 return APIntOps::GreatestCommonDivisor(std::move(A), std::move(B));
3122}
3123
3124/// Get a canonical unsigned division expression, or something simpler if
3125/// possible. There is no representation for an exact udiv in SCEV IR, but we
3126/// can attempt to remove factors from the LHS and RHS. We can't do this when
3127/// it's not exact because the udiv may be clearing bits.
3128const SCEV *ScalarEvolution::getUDivExactExpr(const SCEV *LHS,
3129 const SCEV *RHS) {
3130 // TODO: we could try to find factors in all sorts of things, but for now we
3131 // just deal with u/exact (multiply, constant). See SCEVDivision towards the
3132 // end of this file for inspiration.
3133
3134 const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS);
3135 if (!Mul || !Mul->hasNoUnsignedWrap())
3136 return getUDivExpr(LHS, RHS);
3137
3138 if (const SCEVConstant *RHSCst = dyn_cast<SCEVConstant>(RHS)) {
3139 // If the mulexpr multiplies by a constant, then that constant must be the
3140 // first element of the mulexpr.
3141 if (const auto *LHSCst = dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3142 if (LHSCst == RHSCst) {
3143 SmallVector<const SCEV *, 2> Operands;
3144 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3145 return getMulExpr(Operands);
3146 }
3147
3148 // We can't just assume that LHSCst divides RHSCst cleanly, it could be
3149 // that there's a factor provided by one of the other terms. We need to
3150 // check.
3151 APInt Factor = gcd(LHSCst, RHSCst);
3152 if (!Factor.isIntN(1)) {
3153 LHSCst =
3154 cast<SCEVConstant>(getConstant(LHSCst->getAPInt().udiv(Factor)));
3155 RHSCst =
3156 cast<SCEVConstant>(getConstant(RHSCst->getAPInt().udiv(Factor)));
3157 SmallVector<const SCEV *, 2> Operands;
3158 Operands.push_back(LHSCst);
3159 Operands.append(Mul->op_begin() + 1, Mul->op_end());
3160 LHS = getMulExpr(Operands);
3161 RHS = RHSCst;
3162 Mul = dyn_cast<SCEVMulExpr>(LHS);
3163 if (!Mul)
3164 return getUDivExactExpr(LHS, RHS);
3165 }
3166 }
3167 }
3168
3169 for (int i = 0, e = Mul->getNumOperands(); i != e; ++i) {
3170 if (Mul->getOperand(i) == RHS) {
3171 SmallVector<const SCEV *, 2> Operands;
3172 Operands.append(Mul->op_begin(), Mul->op_begin() + i);
3173 Operands.append(Mul->op_begin() + i + 1, Mul->op_end());
3174 return getMulExpr(Operands);
3175 }
3176 }
3177
3178 return getUDivExpr(LHS, RHS);
3179}
3180
3181/// Get an add recurrence expression for the specified loop. Simplify the
3182/// expression as much as possible.
3183const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start, const SCEV *Step,
3184 const Loop *L,
3185 SCEV::NoWrapFlags Flags) {
3186 SmallVector<const SCEV *, 4> Operands;
3187 Operands.push_back(Start);
3188 if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
3189 if (StepChrec->getLoop() == L) {
3190 Operands.append(StepChrec->op_begin(), StepChrec->op_end());
3191 return getAddRecExpr(Operands, L, maskFlags(Flags, SCEV::FlagNW));
3192 }
3193
3194 Operands.push_back(Step);
3195 return getAddRecExpr(Operands, L, Flags);
3196}
3197
3198/// Get an add recurrence expression for the specified loop. Simplify the
3199/// expression as much as possible.
3200const SCEV *
3201ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
3202 const Loop *L, SCEV::NoWrapFlags Flags) {
3203 if (Operands.size() == 1) return Operands[0];
3204#ifndef NDEBUG
3205 Type *ETy = getEffectiveSCEVType(Operands[0]->getType());
3206 for (unsigned i = 1, e = Operands.size(); i != e; ++i)
3207 assert(getEffectiveSCEVType(Operands[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Operands[i]->
getType()) == ETy && "SCEVAddRecExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3208, __extension__ __PRETTY_FUNCTION__))
3208 "SCEVAddRecExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Operands[i]->
getType()) == ETy && "SCEVAddRecExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Operands[i]->getType()) == ETy && \"SCEVAddRecExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3208, __extension__ __PRETTY_FUNCTION__))
;
3209 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3210 assert(isLoopInvariant(Operands[i], L) &&(static_cast <bool> (isLoopInvariant(Operands[i], L) &&
"SCEVAddRecExpr operand is not loop-invariant!") ? void (0) :
__assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3211, __extension__ __PRETTY_FUNCTION__))
3211 "SCEVAddRecExpr operand is not loop-invariant!")(static_cast <bool> (isLoopInvariant(Operands[i], L) &&
"SCEVAddRecExpr operand is not loop-invariant!") ? void (0) :
__assert_fail ("isLoopInvariant(Operands[i], L) && \"SCEVAddRecExpr operand is not loop-invariant!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3211, __extension__ __PRETTY_FUNCTION__))
;
3212#endif
3213
3214 if (Operands.back()->isZero()) {
3215 Operands.pop_back();
3216 return getAddRecExpr(Operands, L, SCEV::FlagAnyWrap); // {X,+,0} --> X
3217 }
3218
3219 // It's tempting to want to call getMaxBackedgeTakenCount count here and
3220 // use that information to infer NUW and NSW flags. However, computing a
3221 // BE count requires calling getAddRecExpr, so we may not yet have a
3222 // meaningful BE count at this point (and if we don't, we'd be stuck
3223 // with a SCEVCouldNotCompute as the cached BE count).
3224
3225 Flags = StrengthenNoWrapFlags(this, scAddRecExpr, Operands, Flags);
3226
3227 // Canonicalize nested AddRecs in by nesting them in order of loop depth.
3228 if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
3229 const Loop *NestedLoop = NestedAR->getLoop();
3230 if (L->contains(NestedLoop)
3231 ? (L->getLoopDepth() < NestedLoop->getLoopDepth())
3232 : (!NestedLoop->contains(L) &&
3233 DT.dominates(L->getHeader(), NestedLoop->getHeader()))) {
3234 SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(),
3235 NestedAR->op_end());
3236 Operands[0] = NestedAR->getStart();
3237 // AddRecs require their operands be loop-invariant with respect to their
3238 // loops. Don't perform this transformation if it would break this
3239 // requirement.
3240 bool AllInvariant = all_of(
3241 Operands, [&](const SCEV *Op) { return isLoopInvariant(Op, L); });
3242
3243 if (AllInvariant) {
3244 // Create a recurrence for the outer loop with the same step size.
3245 //
3246 // The outer recurrence keeps its NW flag but only keeps NUW/NSW if the
3247 // inner recurrence has the same property.
3248 SCEV::NoWrapFlags OuterFlags =
3249 maskFlags(Flags, SCEV::FlagNW | NestedAR->getNoWrapFlags());
3250
3251 NestedOperands[0] = getAddRecExpr(Operands, L, OuterFlags);
3252 AllInvariant = all_of(NestedOperands, [&](const SCEV *Op) {
3253 return isLoopInvariant(Op, NestedLoop);
3254 });
3255
3256 if (AllInvariant) {
3257 // Ok, both add recurrences are valid after the transformation.
3258 //
3259 // The inner recurrence keeps its NW flag but only keeps NUW/NSW if
3260 // the outer recurrence has the same property.
3261 SCEV::NoWrapFlags InnerFlags =
3262 maskFlags(NestedAR->getNoWrapFlags(), SCEV::FlagNW | Flags);
3263 return getAddRecExpr(NestedOperands, NestedLoop, InnerFlags);
3264 }
3265 }
3266 // Reset Operands to its original state.
3267 Operands[0] = NestedAR;
3268 }
3269 }
3270
3271 // Okay, it looks like we really DO need an addrec expr. Check to see if we
3272 // already have one, otherwise create a new one.
3273 FoldingSetNodeID ID;
3274 ID.AddInteger(scAddRecExpr);
3275 for (unsigned i = 0, e = Operands.size(); i != e; ++i)
3276 ID.AddPointer(Operands[i]);
3277 ID.AddPointer(L);
3278 void *IP = nullptr;
3279 SCEVAddRecExpr *S =
3280 static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
3281 if (!S) {
3282 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Operands.size());
3283 std::uninitialized_copy(Operands.begin(), Operands.end(), O);
3284 S = new (SCEVAllocator) SCEVAddRecExpr(ID.Intern(SCEVAllocator),
3285 O, Operands.size(), L);
3286 UniqueSCEVs.InsertNode(S, IP);
3287 addToLoopUseLists(S);
3288 }
3289 S->setNoWrapFlags(Flags);
3290 return S;
3291}
3292
3293const SCEV *
3294ScalarEvolution::getGEPExpr(GEPOperator *GEP,
3295 const SmallVectorImpl<const SCEV *> &IndexExprs) {
3296 const SCEV *BaseExpr = getSCEV(GEP->getPointerOperand());
3297 // getSCEV(Base)->getType() has the same address space as Base->getType()
3298 // because SCEV::getType() preserves the address space.
3299 Type *IntPtrTy = getEffectiveSCEVType(BaseExpr->getType());
3300 // FIXME(PR23527): Don't blindly transfer the inbounds flag from the GEP
3301 // instruction to its SCEV, because the Instruction may be guarded by control
3302 // flow and the no-overflow bits may not be valid for the expression in any
3303 // context. This can be fixed similarly to how these flags are handled for
3304 // adds.
3305 SCEV::NoWrapFlags Wrap = GEP->isInBounds() ? SCEV::FlagNSW
3306 : SCEV::FlagAnyWrap;
3307
3308 const SCEV *TotalOffset = getZero(IntPtrTy);
3309 // The array size is unimportant. The first thing we do on CurTy is getting
3310 // its element type.
3311 Type *CurTy = ArrayType::get(GEP->getSourceElementType(), 0);
3312 for (const SCEV *IndexExpr : IndexExprs) {
3313 // Compute the (potentially symbolic) offset in bytes for this index.
3314 if (StructType *STy = dyn_cast<StructType>(CurTy)) {
3315 // For a struct, add the member offset.
3316 ConstantInt *Index = cast<SCEVConstant>(IndexExpr)->getValue();
3317 unsigned FieldNo = Index->getZExtValue();
3318 const SCEV *FieldOffset = getOffsetOfExpr(IntPtrTy, STy, FieldNo);
3319
3320 // Add the field offset to the running total offset.
3321 TotalOffset = getAddExpr(TotalOffset, FieldOffset);
3322
3323 // Update CurTy to the type of the field at Index.
3324 CurTy = STy->getTypeAtIndex(Index);
3325 } else {
3326 // Update CurTy to its element type.
3327 CurTy = cast<SequentialType>(CurTy)->getElementType();
3328 // For an array, add the element offset, explicitly scaled.
3329 const SCEV *ElementSize = getSizeOfExpr(IntPtrTy, CurTy);
3330 // Getelementptr indices are signed.
3331 IndexExpr = getTruncateOrSignExtend(IndexExpr, IntPtrTy);
3332
3333 // Multiply the index by the element size to compute the element offset.
3334 const SCEV *LocalOffset = getMulExpr(IndexExpr, ElementSize, Wrap);
3335
3336 // Add the element offset to the running total offset.
3337 TotalOffset = getAddExpr(TotalOffset, LocalOffset);
3338 }
3339 }
3340
3341 // Add the total offset from all the GEP indices to the base.
3342 return getAddExpr(BaseExpr, TotalOffset, Wrap);
3343}
3344
3345const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS,
3346 const SCEV *RHS) {
3347 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3348 return getSMaxExpr(Ops);
3349}
3350
3351const SCEV *
3352ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3353 assert(!Ops.empty() && "Cannot get empty smax!")(static_cast <bool> (!Ops.empty() && "Cannot get empty smax!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty smax!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3353, __extension__ __PRETTY_FUNCTION__))
;
3354 if (Ops.size() == 1) return Ops[0];
3355#ifndef NDEBUG
3356 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3357 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3358 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "SCEVSMaxExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVSMaxExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3359, __extension__ __PRETTY_FUNCTION__))
3359 "SCEVSMaxExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "SCEVSMaxExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVSMaxExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3359, __extension__ __PRETTY_FUNCTION__))
;
3360#endif
3361
3362 // Sort by complexity, this groups all similar expression types together.
3363 GroupByComplexity(Ops, &LI, DT);
3364
3365 // If there are any constants, fold them together.
3366 unsigned Idx = 0;
3367 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3368 ++Idx;
3369 assert(Idx < Ops.size())(static_cast <bool> (Idx < Ops.size()) ? void (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3369, __extension__ __PRETTY_FUNCTION__))
;
3370 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3371 // We found two constants, fold them together!
3372 ConstantInt *Fold = ConstantInt::get(
3373 getContext(), APIntOps::smax(LHSC->getAPInt(), RHSC->getAPInt()));
3374 Ops[0] = getConstant(Fold);
3375 Ops.erase(Ops.begin()+1); // Erase the folded element
3376 if (Ops.size() == 1) return Ops[0];
3377 LHSC = cast<SCEVConstant>(Ops[0]);
3378 }
3379
3380 // If we are left with a constant minimum-int, strip it off.
3381 if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) {
3382 Ops.erase(Ops.begin());
3383 --Idx;
3384 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(true)) {
3385 // If we have an smax with a constant maximum-int, it will always be
3386 // maximum-int.
3387 return Ops[0];
3388 }
3389
3390 if (Ops.size() == 1) return Ops[0];
3391 }
3392
3393 // Find the first SMax
3394 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scSMaxExpr)
3395 ++Idx;
3396
3397 // Check to see if one of the operands is an SMax. If so, expand its operands
3398 // onto our operand list, and recurse to simplify.
3399 if (Idx < Ops.size()) {
3400 bool DeletedSMax = false;
3401 while (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(Ops[Idx])) {
3402 Ops.erase(Ops.begin()+Idx);
3403 Ops.append(SMax->op_begin(), SMax->op_end());
3404 DeletedSMax = true;
3405 }
3406
3407 if (DeletedSMax)
3408 return getSMaxExpr(Ops);
3409 }
3410
3411 // Okay, check to see if the same value occurs in the operand list twice. If
3412 // so, delete one. Since we sorted the list, these values are required to
3413 // be adjacent.
3414 for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
3415 // X smax Y smax Y --> X smax Y
3416 // X smax Y --> X, if X is always greater than Y
3417 if (Ops[i] == Ops[i+1] ||
3418 isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) {
3419 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
3420 --i; --e;
3421 } else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) {
3422 Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
3423 --i; --e;
3424 }
3425
3426 if (Ops.size() == 1) return Ops[0];
3427
3428 assert(!Ops.empty() && "Reduced smax down to nothing!")(static_cast <bool> (!Ops.empty() && "Reduced smax down to nothing!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Reduced smax down to nothing!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3428, __extension__ __PRETTY_FUNCTION__))
;
3429
3430 // Okay, it looks like we really DO need an smax expr. Check to see if we
3431 // already have one, otherwise create a new one.
3432 FoldingSetNodeID ID;
3433 ID.AddInteger(scSMaxExpr);
3434 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3435 ID.AddPointer(Ops[i]);
3436 void *IP = nullptr;
3437 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3438 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3439 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3440 SCEV *S = new (SCEVAllocator) SCEVSMaxExpr(ID.Intern(SCEVAllocator),
3441 O, Ops.size());
3442 UniqueSCEVs.InsertNode(S, IP);
3443 addToLoopUseLists(S);
3444 return S;
3445}
3446
3447const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS,
3448 const SCEV *RHS) {
3449 SmallVector<const SCEV *, 2> Ops = {LHS, RHS};
3450 return getUMaxExpr(Ops);
3451}
3452
3453const SCEV *
3454ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
3455 assert(!Ops.empty() && "Cannot get empty umax!")(static_cast <bool> (!Ops.empty() && "Cannot get empty umax!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Cannot get empty umax!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3455, __extension__ __PRETTY_FUNCTION__))
;
3456 if (Ops.size() == 1) return Ops[0];
3457#ifndef NDEBUG
3458 Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
3459 for (unsigned i = 1, e = Ops.size(); i != e; ++i)
3460 assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "SCEVUMaxExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVUMaxExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3461, __extension__ __PRETTY_FUNCTION__))
3461 "SCEVUMaxExpr operand types don't match!")(static_cast <bool> (getEffectiveSCEVType(Ops[i]->getType
()) == ETy && "SCEVUMaxExpr operand types don't match!"
) ? void (0) : __assert_fail ("getEffectiveSCEVType(Ops[i]->getType()) == ETy && \"SCEVUMaxExpr operand types don't match!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3461, __extension__ __PRETTY_FUNCTION__))
;
3462#endif
3463
3464 // Sort by complexity, this groups all similar expression types together.
3465 GroupByComplexity(Ops, &LI, DT);
3466
3467 // If there are any constants, fold them together.
3468 unsigned Idx = 0;
3469 if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
3470 ++Idx;
3471 assert(Idx < Ops.size())(static_cast <bool> (Idx < Ops.size()) ? void (0) : __assert_fail
("Idx < Ops.size()", "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3471, __extension__ __PRETTY_FUNCTION__))
;
3472 while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
3473 // We found two constants, fold them together!
3474 ConstantInt *Fold = ConstantInt::get(
3475 getContext(), APIntOps::umax(LHSC->getAPInt(), RHSC->getAPInt()));
3476 Ops[0] = getConstant(Fold);
3477 Ops.erase(Ops.begin()+1); // Erase the folded element
3478 if (Ops.size() == 1) return Ops[0];
3479 LHSC = cast<SCEVConstant>(Ops[0]);
3480 }
3481
3482 // If we are left with a constant minimum-int, strip it off.
3483 if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) {
3484 Ops.erase(Ops.begin());
3485 --Idx;
3486 } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(false)) {
3487 // If we have an umax with a constant maximum-int, it will always be
3488 // maximum-int.
3489 return Ops[0];
3490 }
3491
3492 if (Ops.size() == 1) return Ops[0];
3493 }
3494
3495 // Find the first UMax
3496 while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scUMaxExpr)
3497 ++Idx;
3498
3499 // Check to see if one of the operands is a UMax. If so, expand its operands
3500 // onto our operand list, and recurse to simplify.
3501 if (Idx < Ops.size()) {
3502 bool DeletedUMax = false;
3503 while (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(Ops[Idx])) {
3504 Ops.erase(Ops.begin()+Idx);
3505 Ops.append(UMax->op_begin(), UMax->op_end());
3506 DeletedUMax = true;
3507 }
3508
3509 if (DeletedUMax)
3510 return getUMaxExpr(Ops);
3511 }
3512
3513 // Okay, check to see if the same value occurs in the operand list twice. If
3514 // so, delete one. Since we sorted the list, these values are required to
3515 // be adjacent.
3516 for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
3517 // X umax Y umax Y --> X umax Y
3518 // X umax Y --> X, if X is always greater than Y
3519 if (Ops[i] == Ops[i+1] ||
3520 isKnownPredicate(ICmpInst::ICMP_UGE, Ops[i], Ops[i+1])) {
3521 Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
3522 --i; --e;
3523 } else if (isKnownPredicate(ICmpInst::ICMP_ULE, Ops[i], Ops[i+1])) {
3524 Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
3525 --i; --e;
3526 }
3527
3528 if (Ops.size() == 1) return Ops[0];
3529
3530 assert(!Ops.empty() && "Reduced umax down to nothing!")(static_cast <bool> (!Ops.empty() && "Reduced umax down to nothing!"
) ? void (0) : __assert_fail ("!Ops.empty() && \"Reduced umax down to nothing!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3530, __extension__ __PRETTY_FUNCTION__))
;
3531
3532 // Okay, it looks like we really DO need a umax expr. Check to see if we
3533 // already have one, otherwise create a new one.
3534 FoldingSetNodeID ID;
3535 ID.AddInteger(scUMaxExpr);
3536 for (unsigned i = 0, e = Ops.size(); i != e; ++i)
3537 ID.AddPointer(Ops[i]);
3538 void *IP = nullptr;
3539 if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
3540 const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
3541 std::uninitialized_copy(Ops.begin(), Ops.end(), O);
3542 SCEV *S = new (SCEVAllocator) SCEVUMaxExpr(ID.Intern(SCEVAllocator),
3543 O, Ops.size());
3544 UniqueSCEVs.InsertNode(S, IP);
3545 addToLoopUseLists(S);
3546 return S;
3547}
3548
3549const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
3550 const SCEV *RHS) {
3551 // ~smax(~x, ~y) == smin(x, y).
3552 return getNotSCEV(getSMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
3553}
3554
3555const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
3556 const SCEV *RHS) {
3557 // ~umax(~x, ~y) == umin(x, y)
3558 return getNotSCEV(getUMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
3559}
3560
3561const SCEV *ScalarEvolution::getSizeOfExpr(Type *IntTy, Type *AllocTy) {
3562 // We can bypass creating a target-independent
3563 // constant expression and then folding it back into a ConstantInt.
3564 // This is just a compile-time optimization.
3565 return getConstant(IntTy, getDataLayout().getTypeAllocSize(AllocTy));
3566}
3567
3568const SCEV *ScalarEvolution::getOffsetOfExpr(Type *IntTy,
3569 StructType *STy,
3570 unsigned FieldNo) {
3571 // We can bypass creating a target-independent
3572 // constant expression and then folding it back into a ConstantInt.
3573 // This is just a compile-time optimization.
3574 return getConstant(
3575 IntTy, getDataLayout().getStructLayout(STy)->getElementOffset(FieldNo));
3576}
3577
3578const SCEV *ScalarEvolution::getUnknown(Value *V) {
3579 // Don't attempt to do anything other than create a SCEVUnknown object
3580 // here. createSCEV only calls getUnknown after checking for all other
3581 // interesting possibilities, and any other code that calls getUnknown
3582 // is doing so in order to hide a value from SCEV canonicalization.
3583
3584 FoldingSetNodeID ID;
3585 ID.AddInteger(scUnknown);
3586 ID.AddPointer(V);
3587 void *IP = nullptr;
3588 if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
3589 assert(cast<SCEVUnknown>(S)->getValue() == V &&(static_cast <bool> (cast<SCEVUnknown>(S)->getValue
() == V && "Stale SCEVUnknown in uniquing map!") ? void
(0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3590, __extension__ __PRETTY_FUNCTION__))
3590 "Stale SCEVUnknown in uniquing map!")(static_cast <bool> (cast<SCEVUnknown>(S)->getValue
() == V && "Stale SCEVUnknown in uniquing map!") ? void
(0) : __assert_fail ("cast<SCEVUnknown>(S)->getValue() == V && \"Stale SCEVUnknown in uniquing map!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3590, __extension__ __PRETTY_FUNCTION__))
;
3591 return S;
3592 }
3593 SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V, this,
3594 FirstUnknown);
3595 FirstUnknown = cast<SCEVUnknown>(S);
3596 UniqueSCEVs.InsertNode(S, IP);
3597 return S;
3598}
3599
3600//===----------------------------------------------------------------------===//
3601// Basic SCEV Analysis and PHI Idiom Recognition Code
3602//
3603
3604/// Test if values of the given type are analyzable within the SCEV
3605/// framework. This primarily includes integer types, and it can optionally
3606/// include pointer types if the ScalarEvolution class has access to
3607/// target-specific information.
3608bool ScalarEvolution::isSCEVable(Type *Ty) const {
3609 // Integers and pointers are always SCEVable.
3610 return Ty->isIntegerTy() || Ty->isPointerTy();
3611}
3612
3613/// Return the size in bits of the specified type, for which isSCEVable must
3614/// return true.
3615uint64_t ScalarEvolution::getTypeSizeInBits(Type *Ty) const {
3616 assert(isSCEVable(Ty) && "Type is not SCEVable!")(static_cast <bool> (isSCEVable(Ty) && "Type is not SCEVable!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3616, __extension__ __PRETTY_FUNCTION__))
;
3617 if (Ty->isPointerTy())
3618 return getDataLayout().getIndexTypeSizeInBits(Ty);
3619 return getDataLayout().getTypeSizeInBits(Ty);
3620}
3621
3622/// Return a type with the same bitwidth as the given type and which represents
3623/// how SCEV will treat the given type, for which isSCEVable must return
3624/// true. For pointer types, this is the pointer-sized integer type.
3625Type *ScalarEvolution::getEffectiveSCEVType(Type *Ty) const {
3626 assert(isSCEVable(Ty) && "Type is not SCEVable!")(static_cast <bool> (isSCEVable(Ty) && "Type is not SCEVable!"
) ? void (0) : __assert_fail ("isSCEVable(Ty) && \"Type is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3626, __extension__ __PRETTY_FUNCTION__))
;
3627
3628 if (Ty->isIntegerTy())
3629 return Ty;
3630
3631 // The only other support type is pointer.
3632 assert(Ty->isPointerTy() && "Unexpected non-pointer non-integer type!")(static_cast <bool> (Ty->isPointerTy() && "Unexpected non-pointer non-integer type!"
) ? void (0) : __assert_fail ("Ty->isPointerTy() && \"Unexpected non-pointer non-integer type!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3632, __extension__ __PRETTY_FUNCTION__))
;
3633 return getDataLayout().getIntPtrType(Ty);
3634}
3635
3636Type *ScalarEvolution::getWiderType(Type *T1, Type *T2) const {
3637 return getTypeSizeInBits(T1) >= getTypeSizeInBits(T2) ? T1 : T2;
3638}
3639
3640const SCEV *ScalarEvolution::getCouldNotCompute() {
3641 return CouldNotCompute.get();
3642}
3643
3644bool ScalarEvolution::checkValidity(const SCEV *S) const {
3645 bool ContainsNulls = SCEVExprContains(S, [](const SCEV *S) {
3646 auto *SU = dyn_cast<SCEVUnknown>(S);
3647 return SU && SU->getValue() == nullptr;
3648 });
3649
3650 return !ContainsNulls;
3651}
3652
3653bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
3654 HasRecMapType::iterator I = HasRecMap.find(S);
3655 if (I != HasRecMap.end())
3656 return I->second;
3657
3658 bool FoundAddRec = SCEVExprContains(S, isa<SCEVAddRecExpr, const SCEV *>);
3659 HasRecMap.insert({S, FoundAddRec});
3660 return FoundAddRec;
3661}
3662
3663/// Try to split a SCEVAddExpr into a pair of {SCEV, ConstantInt}.
3664/// If \p S is a SCEVAddExpr and is composed of a sub SCEV S' and an
3665/// offset I, then return {S', I}, else return {\p S, nullptr}.
3666static std::pair<const SCEV *, ConstantInt *> splitAddExpr(const SCEV *S) {
3667 const auto *Add = dyn_cast<SCEVAddExpr>(S);
3668 if (!Add)
3669 return {S, nullptr};
3670
3671 if (Add->getNumOperands() != 2)
3672 return {S, nullptr};
3673
3674 auto *ConstOp = dyn_cast<SCEVConstant>(Add->getOperand(0));
3675 if (!ConstOp)
3676 return {S, nullptr};
3677
3678 return {Add->getOperand(1), ConstOp->getValue()};
3679}
3680
3681/// Return the ValueOffsetPair set for \p S. \p S can be represented
3682/// by the value and offset from any ValueOffsetPair in the set.
3683SetVector<ScalarEvolution::ValueOffsetPair> *
3684ScalarEvolution::getSCEVValues(const SCEV *S) {
3685 ExprValueMapType::iterator SI = ExprValueMap.find_as(S);
3686 if (SI == ExprValueMap.end())
3687 return nullptr;
3688#ifndef NDEBUG
3689 if (VerifySCEVMap) {
3690 // Check there is no dangling Value in the set returned.
3691 for (const auto &VE : SI->second)
3692 assert(ValueExprMap.count(VE.first))(static_cast <bool> (ValueExprMap.count(VE.first)) ? void
(0) : __assert_fail ("ValueExprMap.count(VE.first)", "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3692, __extension__ __PRETTY_FUNCTION__))
;
3693 }
3694#endif
3695 return &SI->second;
3696}
3697
3698/// Erase Value from ValueExprMap and ExprValueMap. ValueExprMap.erase(V)
3699/// cannot be used separately. eraseValueFromMap should be used to remove
3700/// V from ValueExprMap and ExprValueMap at the same time.
3701void ScalarEvolution::eraseValueFromMap(Value *V) {
3702 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3703 if (I != ValueExprMap.end()) {
3704 const SCEV *S = I->second;
3705 // Remove {V, 0} from the set of ExprValueMap[S]
3706 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(S))
3707 SV->remove({V, nullptr});
3708
3709 // Remove {V, Offset} from the set of ExprValueMap[Stripped]
3710 const SCEV *Stripped;
3711 ConstantInt *Offset;
3712 std::tie(Stripped, Offset) = splitAddExpr(S);
3713 if (Offset != nullptr) {
3714 if (SetVector<ValueOffsetPair> *SV = getSCEVValues(Stripped))
3715 SV->remove({V, Offset});
3716 }
3717 ValueExprMap.erase(V);
3718 }
3719}
3720
3721/// Check whether value has nuw/nsw/exact set but SCEV does not.
3722/// TODO: In reality it is better to check the poison recursevely
3723/// but this is better than nothing.
3724static bool SCEVLostPoisonFlags(const SCEV *S, const Value *V) {
3725 if (auto *I = dyn_cast<Instruction>(V)) {
3726 if (isa<OverflowingBinaryOperator>(I)) {
3727 if (auto *NS = dyn_cast<SCEVNAryExpr>(S)) {
3728 if (I->hasNoSignedWrap() && !NS->hasNoSignedWrap())
3729 return true;
3730 if (I->hasNoUnsignedWrap() && !NS->hasNoUnsignedWrap())
3731 return true;
3732 }
3733 } else if (isa<PossiblyExactOperator>(I) && I->isExact())
3734 return true;
3735 }
3736 return false;
3737}
3738
3739/// Return an existing SCEV if it exists, otherwise analyze the expression and
3740/// create a new one.
3741const SCEV *ScalarEvolution::getSCEV(Value *V) {
3742 assert(isSCEVable(V->getType()) && "Value is not SCEVable!")(static_cast <bool> (isSCEVable(V->getType()) &&
"Value is not SCEVable!") ? void (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3742, __extension__ __PRETTY_FUNCTION__))
;
3743
3744 const SCEV *S = getExistingSCEV(V);
3745 if (S == nullptr) {
3746 S = createSCEV(V);
3747 // During PHI resolution, it is possible to create two SCEVs for the same
3748 // V, so it is needed to double check whether V->S is inserted into
3749 // ValueExprMap before insert S->{V, 0} into ExprValueMap.
3750 std::pair<ValueExprMapType::iterator, bool> Pair =
3751 ValueExprMap.insert({SCEVCallbackVH(V, this), S});
3752 if (Pair.second && !SCEVLostPoisonFlags(S, V)) {
3753 ExprValueMap[S].insert({V, nullptr});
3754
3755 // If S == Stripped + Offset, add Stripped -> {V, Offset} into
3756 // ExprValueMap.
3757 const SCEV *Stripped = S;
3758 ConstantInt *Offset = nullptr;
3759 std::tie(Stripped, Offset) = splitAddExpr(S);
3760 // If stripped is SCEVUnknown, don't bother to save
3761 // Stripped -> {V, offset}. It doesn't simplify and sometimes even
3762 // increase the complexity of the expansion code.
3763 // If V is GetElementPtrInst, don't save Stripped -> {V, offset}
3764 // because it may generate add/sub instead of GEP in SCEV expansion.
3765 if (Offset != nullptr && !isa<SCEVUnknown>(Stripped) &&
3766 !isa<GetElementPtrInst>(V))
3767 ExprValueMap[Stripped].insert({V, Offset});
3768 }
3769 }
3770 return S;
3771}
3772
3773const SCEV *ScalarEvolution::getExistingSCEV(Value *V) {
3774 assert(isSCEVable(V->getType()) && "Value is not SCEVable!")(static_cast <bool> (isSCEVable(V->getType()) &&
"Value is not SCEVable!") ? void (0) : __assert_fail ("isSCEVable(V->getType()) && \"Value is not SCEVable!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3774, __extension__ __PRETTY_FUNCTION__))
;
3775
3776 ValueExprMapType::iterator I = ValueExprMap.find_as(V);
3777 if (I != ValueExprMap.end()) {
3778 const SCEV *S = I->second;
3779 if (checkValidity(S))
3780 return S;
3781 eraseValueFromMap(V);
3782 forgetMemoizedResults(S);
3783 }
3784 return nullptr;
3785}
3786
3787/// Return a SCEV corresponding to -V = -1*V
3788const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V,
3789 SCEV::NoWrapFlags Flags) {
3790 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3791 return getConstant(
3792 cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
3793
3794 Type *Ty = V->getType();
3795 Ty = getEffectiveSCEVType(Ty);
3796 return getMulExpr(
3797 V, getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))), Flags);
3798}
3799
3800/// Return a SCEV corresponding to ~V = -1-V
3801const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
3802 if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
3803 return getConstant(
3804 cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
3805
3806 Type *Ty = V->getType();
3807 Ty = getEffectiveSCEVType(Ty);
3808 const SCEV *AllOnes =
3809 getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)));
3810 return getMinusSCEV(AllOnes, V);
3811}
3812
3813const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS, const SCEV *RHS,
3814 SCEV::NoWrapFlags Flags,
3815 unsigned Depth) {
3816 // Fast path: X - X --> 0.
3817 if (LHS == RHS)
3818 return getZero(LHS->getType());
3819
3820 // We represent LHS - RHS as LHS + (-1)*RHS. This transformation
3821 // makes it so that we cannot make much use of NUW.
3822 auto AddFlags = SCEV::FlagAnyWrap;
3823 const bool RHSIsNotMinSigned =
3824 !getSignedRangeMin(RHS).isMinSignedValue();
3825 if (maskFlags(Flags, SCEV::FlagNSW) == SCEV::FlagNSW) {
3826 // Let M be the minimum representable signed value. Then (-1)*RHS
3827 // signed-wraps if and only if RHS is M. That can happen even for
3828 // a NSW subtraction because e.g. (-1)*M signed-wraps even though
3829 // -1 - M does not. So to transfer NSW from LHS - RHS to LHS +
3830 // (-1)*RHS, we need to prove that RHS != M.
3831 //
3832 // If LHS is non-negative and we know that LHS - RHS does not
3833 // signed-wrap, then RHS cannot be M. So we can rule out signed-wrap
3834 // either by proving that RHS > M or that LHS >= 0.
3835 if (RHSIsNotMinSigned || isKnownNonNegative(LHS)) {
3836 AddFlags = SCEV::FlagNSW;
3837 }
3838 }
3839
3840 // FIXME: Find a correct way to transfer NSW to (-1)*M when LHS -
3841 // RHS is NSW and LHS >= 0.
3842 //
3843 // The difficulty here is that the NSW flag may have been proven
3844 // relative to a loop that is to be found in a recurrence in LHS and
3845 // not in RHS. Applying NSW to (-1)*M may then let the NSW have a
3846 // larger scope than intended.
3847 auto NegFlags = RHSIsNotMinSigned ? SCEV::FlagNSW : SCEV::FlagAnyWrap;
3848
3849 return getAddExpr(LHS, getNegativeSCEV(RHS, NegFlags), AddFlags, Depth);
3850}
3851
3852const SCEV *
3853ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V, Type *Ty) {
3854 Type *SrcTy = V->getType();
3855 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3857, __extension__ __PRETTY_FUNCTION__))
3856 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3857, __extension__ __PRETTY_FUNCTION__))
3857 "Cannot truncate or zero extend with non-integer arguments!")(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3857, __extension__ __PRETTY_FUNCTION__))
;
3858 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3859 return V; // No conversion
3860 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3861 return getTruncateExpr(V, Ty);
3862 return getZeroExtendExpr(V, Ty);
3863}
3864
3865const SCEV *
3866ScalarEvolution::getTruncateOrSignExtend(const SCEV *V,
3867 Type *Ty) {
3868 Type *SrcTy = V->getType();
3869 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3871, __extension__ __PRETTY_FUNCTION__))
3870 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3871, __extension__ __PRETTY_FUNCTION__))
3871 "Cannot truncate or zero extend with non-integer arguments!")(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate or zero extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3871, __extension__ __PRETTY_FUNCTION__))
;
3872 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3873 return V; // No conversion
3874 if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
3875 return getTruncateExpr(V, Ty);
3876 return getSignExtendExpr(V, Ty);
3877}
3878
3879const SCEV *
3880ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, Type *Ty) {
3881 Type *SrcTy = V->getType();
3882 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot noop or zero extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3884, __extension__ __PRETTY_FUNCTION__))
3883 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot noop or zero extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3884, __extension__ __PRETTY_FUNCTION__))
3884 "Cannot noop or zero extend with non-integer arguments!")(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot noop or zero extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3884, __extension__ __PRETTY_FUNCTION__))
;
3885 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrZeroExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3886, __extension__ __PRETTY_FUNCTION__))
3886 "getNoopOrZeroExtend cannot truncate!")(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrZeroExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrZeroExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3886, __extension__ __PRETTY_FUNCTION__))
;
3887 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3888 return V; // No conversion
3889 return getZeroExtendExpr(V, Ty);
3890}
3891
3892const SCEV *
3893ScalarEvolution::getNoopOrSignExtend(const SCEV *V, Type *Ty) {
3894 Type *SrcTy = V->getType();
3895 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot noop or sign extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3897, __extension__ __PRETTY_FUNCTION__))
3896 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot noop or sign extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3897, __extension__ __PRETTY_FUNCTION__))
3897 "Cannot noop or sign extend with non-integer arguments!")(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot noop or sign extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3897, __extension__ __PRETTY_FUNCTION__))
;
3898 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrSignExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3899, __extension__ __PRETTY_FUNCTION__))
3899 "getNoopOrSignExtend cannot truncate!")(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrSignExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrSignExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3899, __extension__ __PRETTY_FUNCTION__))
;
3900 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3901 return V; // No conversion
3902 return getSignExtendExpr(V, Ty);
3903}
3904
3905const SCEV *
3906ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, Type *Ty) {
3907 Type *SrcTy = V->getType();
3908 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot noop or any extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3910, __extension__ __PRETTY_FUNCTION__))
3909 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot noop or any extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3910, __extension__ __PRETTY_FUNCTION__))
3910 "Cannot noop or any extend with non-integer arguments!")(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot noop or any extend with non-integer arguments!"
) ? 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-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3910, __extension__ __PRETTY_FUNCTION__))
;
3911 assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrAnyExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3912, __extension__ __PRETTY_FUNCTION__))
3912 "getNoopOrAnyExtend cannot truncate!")(static_cast <bool> (getTypeSizeInBits(SrcTy) <= getTypeSizeInBits
(Ty) && "getNoopOrAnyExtend cannot truncate!") ? void
(0) : __assert_fail ("getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) && \"getNoopOrAnyExtend cannot truncate!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3912, __extension__ __PRETTY_FUNCTION__))
;
3913 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3914 return V; // No conversion
3915 return getAnyExtendExpr(V, Ty);
3916}
3917
3918const SCEV *
3919ScalarEvolution::getTruncateOrNoop(const SCEV *V, Type *Ty) {
3920 Type *SrcTy = V->getType();
3921 assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate or noop with non-integer arguments!"
) ? void (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3923, __extension__ __PRETTY_FUNCTION__))
3922 (Ty->isIntegerTy() || Ty->isPointerTy()) &&(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate or noop with non-integer arguments!"
) ? void (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3923, __extension__ __PRETTY_FUNCTION__))
3923 "Cannot truncate or noop with non-integer arguments!")(static_cast <bool> ((SrcTy->isIntegerTy() || SrcTy->
isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy
()) && "Cannot truncate or noop with non-integer arguments!"
) ? void (0) : __assert_fail ("(SrcTy->isIntegerTy() || SrcTy->isPointerTy()) && (Ty->isIntegerTy() || Ty->isPointerTy()) && \"Cannot truncate or noop with non-integer arguments!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3923, __extension__ __PRETTY_FUNCTION__))
;
3924 assert(getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&(static_cast <bool> (getTypeSizeInBits(SrcTy) >= getTypeSizeInBits
(Ty) && "getTruncateOrNoop cannot extend!") ? void (0
) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3925, __extension__ __PRETTY_FUNCTION__))
3925 "getTruncateOrNoop cannot extend!")(static_cast <bool> (getTypeSizeInBits(SrcTy) >= getTypeSizeInBits
(Ty) && "getTruncateOrNoop cannot extend!") ? void (0
) : __assert_fail ("getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) && \"getTruncateOrNoop cannot extend!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 3925, __extension__ __PRETTY_FUNCTION__))
;
3926 if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
3927 return V; // No conversion
3928 return getTruncateExpr(V, Ty);
3929}
3930
3931const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
3932 const SCEV *RHS) {
3933 const SCEV *PromotedLHS = LHS;
3934 const SCEV *PromotedRHS = RHS;
3935
3936 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3937 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3938 else
3939 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3940
3941 return getUMaxExpr(PromotedLHS, PromotedRHS);
3942}
3943
3944const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
3945 const SCEV *RHS) {
3946 const SCEV *PromotedLHS = LHS;
3947 const SCEV *PromotedRHS = RHS;
3948
3949 if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
3950 PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
3951 else
3952 PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
3953
3954 return getUMinExpr(PromotedLHS, PromotedRHS);
3955}
3956
3957const SCEV *ScalarEvolution::getPointerBase(const SCEV *V) {
3958 // A pointer operand may evaluate to a nonpointer expression, such as null.
3959 if (!V->getType()->isPointerTy())
3960 return V;
3961
3962 if (const SCEVCastExpr *Cast = dyn_cast<SCEVCastExpr>(V)) {
3963 return getPointerBase(Cast->getOperand());
3964 } else if (const SCEVNAryExpr *NAry = dyn_cast<SCEVNAryExpr>(V)) {
3965 const SCEV *PtrOp = nullptr;
3966 for (const SCEV *NAryOp : NAry->operands()) {
3967 if (NAryOp->getType()->isPointerTy()) {
3968 // Cannot find the base of an expression with multiple pointer operands.
3969 if (PtrOp)
3970 return V;
3971 PtrOp = NAryOp;
3972 }
3973 }
3974 if (!PtrOp)
3975 return V;
3976 return getPointerBase(PtrOp);
3977 }
3978 return V;
3979}
3980
3981/// Push users of the given Instruction onto the given Worklist.
3982static void
3983PushDefUseChildren(Instruction *I,
3984 SmallVectorImpl<Instruction *> &Worklist) {
3985 // Push the def-use children onto the Worklist stack.
3986 for (User *U : I->users())
3987 Worklist.push_back(cast<Instruction>(U));
3988}
3989
3990void ScalarEvolution::forgetSymbolicName(Instruction *PN, const SCEV *SymName) {
3991 SmallVector<Instruction *, 16> Worklist;
3992 PushDefUseChildren(PN, Worklist);
3993
3994 SmallPtrSet<Instruction *, 8> Visited;
3995 Visited.insert(PN);
3996 while (!Worklist.empty()) {
3997 Instruction *I = Worklist.pop_back_val();
3998 if (!Visited.insert(I).second)
3999 continue;
4000
4001 auto It = ValueExprMap.find_as(static_cast<Value *>(I));
4002 if (It != ValueExprMap.end()) {
4003 const SCEV *Old = It->second;
4004
4005 // Short-circuit the def-use traversal if the symbolic name
4006 // ceases to appear in expressions.
4007 if (Old != SymName && !hasOperand(Old, SymName))
4008 continue;
4009
4010 // SCEVUnknown for a PHI either means that it has an unrecognized
4011 // structure, it's a PHI that's in the progress of being computed
4012 // by createNodeForPHI, or it's a single-value PHI. In the first case,
4013 // additional loop trip count information isn't going to change anything.
4014 // In the second case, createNodeForPHI will perform the necessary
4015 // updates on its own when it gets to that point. In the third, we do
4016 // want to forget the SCEVUnknown.
4017 if (!isa<PHINode>(I) ||
4018 !isa<SCEVUnknown>(Old) ||
4019 (I != PN && Old == SymName)) {
4020 eraseValueFromMap(It->first);
4021 forgetMemoizedResults(Old);
4022 }
4023 }
4024
4025 PushDefUseChildren(I, Worklist);
4026 }
4027}
4028
4029namespace {
4030
4031/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its start
4032/// expression in case its Loop is L. If it is not L then
4033/// if IgnoreOtherLoops is true then use AddRec itself
4034/// otherwise rewrite cannot be done.
4035/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4036class SCEVInitRewriter : public SCEVRewriteVisitor<SCEVInitRewriter> {
4037public:
4038 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE,
4039 bool IgnoreOtherLoops = true) {
4040 SCEVInitRewriter Rewriter(L, SE);
4041 const SCEV *Result = Rewriter.visit(S);
4042 if (Rewriter.hasSeenLoopVariantSCEVUnknown())
4043 return SE.getCouldNotCompute();
4044 return Rewriter.hasSeenOtherLoops() && !IgnoreOtherLoops
4045 ? SE.getCouldNotCompute()
4046 : Result;
4047 }
4048
4049 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4050 if (!SE.isLoopInvariant(Expr, L))
4051 SeenLoopVariantSCEVUnknown = true;
4052 return Expr;
4053 }
4054
4055 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4056 // Only re-write AddRecExprs for this loop.
4057 if (Expr->getLoop() == L)
4058 return Expr->getStart();
4059 SeenOtherLoops = true;
4060 return Expr;
4061 }
4062
4063 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4064
4065 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4066
4067private:
4068 explicit SCEVInitRewriter(const Loop *L, ScalarEvolution &SE)
4069 : SCEVRewriteVisitor(SE), L(L) {}
4070
4071 const Loop *L;
4072 bool SeenLoopVariantSCEVUnknown = false;
4073 bool SeenOtherLoops = false;
4074};
4075
4076/// Takes SCEV S and Loop L. For each AddRec sub-expression, use its post
4077/// increment expression in case its Loop is L. If it is not L then
4078/// use AddRec itself.
4079/// If SCEV contains non-invariant unknown SCEV rewrite cannot be done.
4080class SCEVPostIncRewriter : public SCEVRewriteVisitor<SCEVPostIncRewriter> {
4081public:
4082 static const SCEV *rewrite(const SCEV *S, const Loop *L, ScalarEvolution &SE) {
4083 SCEVPostIncRewriter Rewriter(L, SE);
4084 const SCEV *Result = Rewriter.visit(S);
4085 return Rewriter.hasSeenLoopVariantSCEVUnknown()
4086 ? SE.getCouldNotCompute()
4087 : Result;
4088 }
4089
4090 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4091 if (!SE.isLoopInvariant(Expr, L))
4092 SeenLoopVariantSCEVUnknown = true;
4093 return Expr;
4094 }
4095
4096 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4097 // Only re-write AddRecExprs for this loop.
4098 if (Expr->getLoop() == L)
4099 return Expr->getPostIncExpr(SE);
4100 SeenOtherLoops = true;
4101 return Expr;
4102 }
4103
4104 bool hasSeenLoopVariantSCEVUnknown() { return SeenLoopVariantSCEVUnknown; }
4105
4106 bool hasSeenOtherLoops() { return SeenOtherLoops; }
4107
4108private:
4109 explicit SCEVPostIncRewriter(const Loop *L, ScalarEvolution &SE)
4110 : SCEVRewriteVisitor(SE), L(L) {}
4111
4112 const Loop *L;
4113 bool SeenLoopVariantSCEVUnknown = false;
4114 bool SeenOtherLoops = false;
4115};
4116
4117/// This class evaluates the compare condition by matching it against the
4118/// condition of loop latch. If there is a match we assume a true value
4119/// for the condition while building SCEV nodes.
4120class SCEVBackedgeConditionFolder
4121 : public SCEVRewriteVisitor<SCEVBackedgeConditionFolder> {
4122public:
4123 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4124 ScalarEvolution &SE) {
4125 bool IsPosBECond = false;
4126 Value *BECond = nullptr;
4127 if (BasicBlock *Latch = L->getLoopLatch()) {
4128 BranchInst *BI = dyn_cast<BranchInst>(Latch->getTerminator());
4129 if (BI && BI->isConditional()) {
4130 assert(BI->getSuccessor(0) != BI->getSuccessor(1) &&(static_cast <bool> (BI->getSuccessor(0) != BI->getSuccessor
(1) && "Both outgoing branches should not target same header!"
) ? void (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 4131, __extension__ __PRETTY_FUNCTION__))
4131 "Both outgoing branches should not target same header!")(static_cast <bool> (BI->getSuccessor(0) != BI->getSuccessor
(1) && "Both outgoing branches should not target same header!"
) ? void (0) : __assert_fail ("BI->getSuccessor(0) != BI->getSuccessor(1) && \"Both outgoing branches should not target same header!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 4131, __extension__ __PRETTY_FUNCTION__))
;
4132 BECond = BI->getCondition();
4133 IsPosBECond = BI->getSuccessor(0) == L->getHeader();
4134 } else {
4135 return S;
4136 }
4137 }
4138 SCEVBackedgeConditionFolder Rewriter(L, BECond, IsPosBECond, SE);
4139 return Rewriter.visit(S);
4140 }
4141
4142 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4143 const SCEV *Result = Expr;
4144 bool InvariantF = SE.isLoopInvariant(Expr, L);
4145
4146 if (!InvariantF) {
4147 Instruction *I = cast<Instruction>(Expr->getValue());
4148 switch (I->getOpcode()) {
4149 case Instruction::Select: {
4150 SelectInst *SI = cast<SelectInst>(I);
4151 Optional<const SCEV *> Res =
4152 compareWithBackedgeCondition(SI->getCondition());
4153 if (Res.hasValue()) {
4154 bool IsOne = cast<SCEVConstant>(Res.getValue())->getValue()->isOne();
4155 Result = SE.getSCEV(IsOne ? SI->getTrueValue() : SI->getFalseValue());
4156 }
4157 break;
4158 }
4159 default: {
4160 Optional<const SCEV *> Res = compareWithBackedgeCondition(I);
4161 if (Res.hasValue())
4162 Result = Res.getValue();
4163 break;
4164 }
4165 }
4166 }
4167 return Result;
4168 }
4169
4170private:
4171 explicit SCEVBackedgeConditionFolder(const Loop *L, Value *BECond,
4172 bool IsPosBECond, ScalarEvolution &SE)
4173 : SCEVRewriteVisitor(SE), L(L), BackedgeCond(BECond),
4174 IsPositiveBECond(IsPosBECond) {}
4175
4176 Optional<const SCEV *> compareWithBackedgeCondition(Value *IC);
4177
4178 const Loop *L;
4179 /// Loop back condition.
4180 Value *BackedgeCond = nullptr;
4181 /// Set to true if loop back is on positive branch condition.
4182 bool IsPositiveBECond;
4183};
4184
4185Optional<const SCEV *>
4186SCEVBackedgeConditionFolder::compareWithBackedgeCondition(Value *IC) {
4187
4188 // If value matches the backedge condition for loop latch,
4189 // then return a constant evolution node based on loopback
4190 // branch taken.
4191 if (BackedgeCond == IC)
4192 return IsPositiveBECond ? SE.getOne(Type::getInt1Ty(SE.getContext()))
4193 : SE.getZero(Type::getInt1Ty(SE.getContext()));
4194 return None;
4195}
4196
4197class SCEVShiftRewriter : public SCEVRewriteVisitor<SCEVShiftRewriter> {
4198public:
4199 static const SCEV *rewrite(const SCEV *S, const Loop *L,
4200 ScalarEvolution &SE) {
4201 SCEVShiftRewriter Rewriter(L, SE);
4202 const SCEV *Result = Rewriter.visit(S);
4203 return Rewriter.isValid() ? Result : SE.getCouldNotCompute();
4204 }
4205
4206 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
4207 // Only allow AddRecExprs for this loop.
4208 if (!SE.isLoopInvariant(Expr, L))
4209 Valid = false;
4210 return Expr;
4211 }
4212
4213 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
4214 if (Expr->getLoop() == L && Expr->isAffine())
4215 return SE.getMinusSCEV(Expr, Expr->getStepRecurrence(SE));
4216 Valid = false;
4217 return Expr;
4218 }
4219
4220 bool isValid() { return Valid; }
4221
4222private:
4223 explicit SCEVShiftRewriter(const Loop *L, ScalarEvolution &SE)
4224 : SCEVRewriteVisitor(SE), L(L) {}
4225
4226 const Loop *L;
4227 bool Valid = true;
4228};
4229
4230} // end anonymous namespace
4231
4232SCEV::NoWrapFlags
4233ScalarEvolution::proveNoWrapViaConstantRanges(const SCEVAddRecExpr *AR) {
4234 if (!AR->isAffine())
4235 return SCEV::FlagAnyWrap;
4236
4237 using OBO = OverflowingBinaryOperator;
4238
4239 SCEV::NoWrapFlags Result = SCEV::FlagAnyWrap;
4240
4241 if (!AR->hasNoSignedWrap()) {
4242 ConstantRange AddRecRange = getSignedRange(AR);
4243 ConstantRange IncRange = getSignedRange(AR->getStepRecurrence(*this));
4244
4245 auto NSWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4246 Instruction::Add, IncRange, OBO::NoSignedWrap);
4247 if (NSWRegion.contains(AddRecRange))
4248 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNSW);
4249 }
4250
4251 if (!AR->hasNoUnsignedWrap()) {
4252 ConstantRange AddRecRange = getUnsignedRange(AR);
4253 ConstantRange IncRange = getUnsignedRange(AR->getStepRecurrence(*this));
4254
4255 auto NUWRegion = ConstantRange::makeGuaranteedNoWrapRegion(
4256 Instruction::Add, IncRange, OBO::NoUnsignedWrap);
4257 if (NUWRegion.contains(AddRecRange))
4258 Result = ScalarEvolution::setFlags(Result, SCEV::FlagNUW);
4259 }
4260
4261 return Result;
4262}
4263
4264namespace {
4265
4266/// Represents an abstract binary operation. This may exist as a
4267/// normal instruction or constant expression, or may have been
4268/// derived from an expression tree.
4269struct BinaryOp {
4270 unsigned Opcode;
4271 Value *LHS;
4272 Value *RHS;
4273 bool IsNSW = false;
4274 bool IsNUW = false;
4275
4276 /// Op is set if this BinaryOp corresponds to a concrete LLVM instruction or
4277 /// constant expression.
4278 Operator *Op = nullptr;
4279
4280 explicit BinaryOp(Operator *Op)
4281 : Opcode(Op->getOpcode()), LHS(Op->getOperand(0)), RHS(Op->getOperand(1)),
4282 Op(Op) {
4283 if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(Op)) {
4284 IsNSW = OBO->hasNoSignedWrap();
4285 IsNUW = OBO->hasNoUnsignedWrap();
4286 }
4287 }
4288
4289 explicit BinaryOp(unsigned Opcode, Value *LHS, Value *RHS, bool IsNSW = false,
4290 bool IsNUW = false)
4291 : Opcode(Opcode), LHS(LHS), RHS(RHS), IsNSW(IsNSW), IsNUW(IsNUW) {}
4292};
4293
4294} // end anonymous namespace
4295
4296/// Try to map \p V into a BinaryOp, and return \c None on failure.
4297static Optional<BinaryOp> MatchBinaryOp(Value *V, DominatorTree &DT) {
4298 auto *Op = dyn_cast<Operator>(V);
4299 if (!Op)
4300 return None;
4301
4302 // Implementation detail: all the cleverness here should happen without
4303 // creating new SCEV expressions -- our caller knowns tricks to avoid creating
4304 // SCEV expressions when possible, and we should not break that.
4305
4306 switch (Op->getOpcode()) {
4307 case Instruction::Add:
4308 case Instruction::Sub:
4309 case Instruction::Mul:
4310 case Instruction::UDiv:
4311 case Instruction::URem:
4312 case Instruction::And:
4313 case Instruction::Or:
4314 case Instruction::AShr:
4315 case Instruction::Shl:
4316 return BinaryOp(Op);
4317
4318 case Instruction::Xor:
4319 if (auto *RHSC = dyn_cast<ConstantInt>(Op->getOperand(1)))
4320 // If the RHS of the xor is a signmask, then this is just an add.
4321 // Instcombine turns add of signmask into xor as a strength reduction step.
4322 if (RHSC->getValue().isSignMask())
4323 return BinaryOp(Instruction::Add, Op->getOperand(0), Op->getOperand(1));
4324 return BinaryOp(Op);
4325
4326 case Instruction::LShr:
4327 // Turn logical shift right of a constant into a unsigned divide.
4328 if (ConstantInt *SA = dyn_cast<ConstantInt>(Op->getOperand(1))) {
4329 uint32_t BitWidth = cast<IntegerType>(Op->getType())->getBitWidth();
4330
4331 // If the shift count is not less than the bitwidth, the result of
4332 // the shift is undefined. Don't try to analyze it, because the
4333 // resolution chosen here may differ from the resolution chosen in
4334 // other parts of the compiler.
4335 if (SA->getValue().ult(BitWidth)) {
4336 Constant *X =
4337 ConstantInt::get(SA->getContext(),
4338 APInt::getOneBitSet(BitWidth, SA->getZExtValue()));
4339 return BinaryOp(Instruction::UDiv, Op->getOperand(0), X);
4340 }
4341 }
4342 return BinaryOp(Op);
4343
4344 case Instruction::ExtractValue: {
4345 auto *EVI = cast<ExtractValueInst>(Op);
4346 if (EVI->getNumIndices() != 1 || EVI->getIndices()[0] != 0)
4347 break;
4348
4349 auto *CI = dyn_cast<CallInst>(EVI->getAggregateOperand());
4350 if (!CI)
4351 break;
4352
4353 if (auto *F = CI->getCalledFunction())
4354 switch (F->getIntrinsicID()) {
4355 case Intrinsic::sadd_with_overflow:
4356 case Intrinsic::uadd_with_overflow:
4357 if (!isOverflowIntrinsicNoWrap(cast<IntrinsicInst>(CI), DT))
4358 return BinaryOp(Instruction::Add, CI->getArgOperand(0),
4359 CI->getArgOperand(1));
4360
4361 // Now that we know that all uses of the arithmetic-result component of
4362 // CI are guarded by the overflow check, we can go ahead and pretend
4363 // that the arithmetic is non-overflowing.
4364 if (F->getIntrinsicID() == Intrinsic::sadd_with_overflow)
4365 return BinaryOp(Instruction::Add, CI->getArgOperand(0),
4366 CI->getArgOperand(1), /* IsNSW = */ true,
4367 /* IsNUW = */ false);
4368 else
4369 return BinaryOp(Instruction::Add, CI->getArgOperand(0),
4370 CI->getArgOperand(1), /* IsNSW = */ false,
4371 /* IsNUW*/ true);
4372 case Intrinsic::ssub_with_overflow:
4373 case Intrinsic::usub_with_overflow:
4374 if (!isOverflowIntrinsicNoWrap(cast<IntrinsicInst>(CI), DT))
4375 return BinaryOp(Instruction::Sub, CI->getArgOperand(0),
4376 CI->getArgOperand(1));
4377
4378 // The same reasoning as sadd/uadd above.
4379 if (F->getIntrinsicID() == Intrinsic::ssub_with_overflow)
4380 return BinaryOp(Instruction::Sub, CI->getArgOperand(0),
4381 CI->getArgOperand(1), /* IsNSW = */ true,
4382 /* IsNUW = */ false);
4383 else
4384 return BinaryOp(Instruction::Sub, CI->getArgOperand(0),
4385 CI->getArgOperand(1), /* IsNSW = */ false,
4386 /* IsNUW = */ true);
4387 case Intrinsic::smul_with_overflow:
4388 case Intrinsic::umul_with_overflow:
4389 return BinaryOp(Instruction::Mul, CI->getArgOperand(0),
4390 CI->getArgOperand(1));
4391 default:
4392 break;
4393 }
4394 break;
4395 }
4396
4397 default:
4398 break;
4399 }
4400
4401 return None;
4402}
4403
4404/// Helper function to createAddRecFromPHIWithCasts. We have a phi
4405/// node whose symbolic (unknown) SCEV is \p SymbolicPHI, which is updated via
4406/// the loop backedge by a SCEVAddExpr, possibly also with a few casts on the
4407/// way. This function checks if \p Op, an operand of this SCEVAddExpr,
4408/// follows one of the following patterns:
4409/// Op == (SExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4410/// Op == (ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy)
4411/// If the SCEV expression of \p Op conforms with one of the expected patterns
4412/// we return the type of the truncation operation, and indicate whether the
4413/// truncated type should be treated as signed/unsigned by setting
4414/// \p Signed to true/false, respectively.
4415static Type *isSimpleCastedPHI(const SCEV *Op, const SCEVUnknown *SymbolicPHI,
4416 bool &Signed, ScalarEvolution &SE) {
4417 // The case where Op == SymbolicPHI (that is, with no type conversions on
4418 // the way) is handled by the regular add recurrence creating logic and
4419 // would have already been triggered in createAddRecForPHI. Reaching it here
4420 // means that createAddRecFromPHI had failed for this PHI before (e.g.,
4421 // because one of the other operands of the SCEVAddExpr updating this PHI is
4422 // not invariant).
4423 //
4424 // Here we look for the case where Op = (ext(trunc(SymbolicPHI))), and in
4425 // this case predicates that allow us to prove that Op == SymbolicPHI will
4426 // be added.
4427 if (Op == SymbolicPHI)
4428 return nullptr;
4429
4430 unsigned SourceBits = SE.getTypeSizeInBits(SymbolicPHI->getType());
4431 unsigned NewBits = SE.getTypeSizeInBits(Op->getType());
4432 if (SourceBits != NewBits)
4433 return nullptr;
4434
4435 const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(Op);
4436 const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(Op);
4437 if (!SExt && !ZExt)
4438 return nullptr;
4439 const SCEVTruncateExpr *Trunc =
4440 SExt ? dyn_cast<SCEVTruncateExpr>(SExt->getOperand())
4441 : dyn_cast<SCEVTruncateExpr>(ZExt->getOperand());
4442 if (!Trunc)
4443 return nullptr;
4444 const SCEV *X = Trunc->getOperand();
4445 if (X != SymbolicPHI)
4446 return nullptr;
4447 Signed = SExt != nullptr;
4448 return Trunc->getType();
4449}
4450
4451static const Loop *isIntegerLoopHeaderPHI(const PHINode *PN, LoopInfo &LI) {
4452 if (!PN->getType()->isIntegerTy())
4453 return nullptr;
4454 const Loop *L = LI.getLoopFor(PN->getParent());
4455 if (!L || L->getHeader() != PN->getParent())
4456 return nullptr;
4457 return L;
4458}
4459
4460// Analyze \p SymbolicPHI, a SCEV expression of a phi node, and check if the
4461// computation that updates the phi follows the following pattern:
4462// (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum
4463// which correspond to a phi->trunc->sext/zext->add->phi update chain.
4464// If so, try to see if it can be rewritten as an AddRecExpr under some
4465// Predicates. If successful, return them as a pair. Also cache the results
4466// of the analysis.
4467//
4468// Example usage scenario:
4469// Say the Rewriter is called for the following SCEV:
4470// 8 * ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4471// where:
4472// %X = phi i64 (%Start, %BEValue)
4473// It will visitMul->visitAdd->visitSExt->visitTrunc->visitUnknown(%X),
4474// and call this function with %SymbolicPHI = %X.
4475//
4476// The analysis will find that the value coming around the backedge has
4477// the following SCEV:
4478// BEValue = ((sext i32 (trunc i64 %X to i32) to i64) + %Step)
4479// Upon concluding that this matches the desired pattern, the function
4480// will return the pair {NewAddRec, SmallPredsVec} where:
4481// NewAddRec = {%Start,+,%Step}
4482// SmallPredsVec = {P1, P2, P3} as follows:
4483// P1(WrapPred): AR: {trunc(%Start),+,(trunc %Step)}<nsw> Flags: <nssw>
4484// P2(EqualPred): %Start == (sext i32 (trunc i64 %Start to i32) to i64)
4485// P3(EqualPred): %Step == (sext i32 (trunc i64 %Step to i32) to i64)
4486// The returned pair means that SymbolicPHI can be rewritten into NewAddRec
4487// under the predicates {P1,P2,P3}.
4488// This predicated rewrite will be cached in PredicatedSCEVRewrites:
4489// PredicatedSCEVRewrites[{%X,L}] = {NewAddRec, {P1,P2,P3)}
4490//
4491// TODO's:
4492//
4493// 1) Extend the Induction descriptor to also support inductions that involve
4494// casts: When needed (namely, when we are called in the context of the
4495// vectorizer induction analysis), a Set of cast instructions will be
4496// populated by this method, and provided back to isInductionPHI. This is
4497// needed to allow the vectorizer to properly record them to be ignored by
4498// the cost model and to avoid vectorizing them (otherwise these casts,
4499// which are redundant under the runtime overflow checks, will be
4500// vectorized, which can be costly).
4501//
4502// 2) Support additional induction/PHISCEV patterns: We also want to support
4503// inductions where the sext-trunc / zext-trunc operations (partly) occur
4504// after the induction update operation (the induction increment):
4505//
4506// (Trunc iy (SExt/ZExt ix (%SymbolicPHI + InvariantAccum) to iy) to ix)
4507// which correspond to a phi->add->trunc->sext/zext->phi update chain.
4508//
4509// (Trunc iy ((SExt/ZExt ix (%SymbolicPhi) to iy) + InvariantAccum) to ix)
4510// which correspond to a phi->trunc->add->sext/zext->phi update chain.
4511//
4512// 3) Outline common code with createAddRecFromPHI to avoid duplication.
4513Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4514ScalarEvolution::createAddRecFromPHIWithCastsImpl(const SCEVUnknown *SymbolicPHI) {
4515 SmallVector<const SCEVPredicate *, 3> Predicates;
4516
4517 // *** Part1: Analyze if we have a phi-with-cast pattern for which we can
4518 // return an AddRec expression under some predicate.
4519
4520 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4521 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4522 assert(L && "Expecting an integer loop header phi")(static_cast <bool> (L && "Expecting an integer loop header phi"
) ? void (0) : __assert_fail ("L && \"Expecting an integer loop header phi\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 4522, __extension__ __PRETTY_FUNCTION__))
;
4523
4524 // The loop may have multiple entrances or multiple exits; we can analyze
4525 // this phi as an addrec if it has a unique entry value and a unique
4526 // backedge value.
4527 Value *BEValueV = nullptr, *StartValueV = nullptr;
4528 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4529 Value *V = PN->getIncomingValue(i);
4530 if (L->contains(PN->getIncomingBlock(i))) {
4531 if (!BEValueV) {
4532 BEValueV = V;
4533 } else if (BEValueV != V) {
4534 BEValueV = nullptr;
4535 break;
4536 }
4537 } else if (!StartValueV) {
4538 StartValueV = V;
4539 } else if (StartValueV != V) {
4540 StartValueV = nullptr;
4541 break;
4542 }
4543 }
4544 if (!BEValueV || !StartValueV)
4545 return None;
4546
4547 const SCEV *BEValue = getSCEV(BEValueV);
4548
4549 // If the value coming around the backedge is an add with the symbolic
4550 // value we just inserted, possibly with casts that we can ignore under
4551 // an appropriate runtime guard, then we found a simple induction variable!
4552 const auto *Add = dyn_cast<SCEVAddExpr>(BEValue);
4553 if (!Add)
4554 return None;
4555
4556 // If there is a single occurrence of the symbolic value, possibly
4557 // casted, replace it with a recurrence.
4558 unsigned FoundIndex = Add->getNumOperands();
4559 Type *TruncTy = nullptr;
4560 bool Signed;
4561 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4562 if ((TruncTy =
4563 isSimpleCastedPHI(Add->getOperand(i), SymbolicPHI, Signed, *this)))
4564 if (FoundIndex == e) {
4565 FoundIndex = i;
4566 break;
4567 }
4568
4569 if (FoundIndex == Add->getNumOperands())
4570 return None;
4571
4572 // Create an add with everything but the specified operand.
4573 SmallVector<const SCEV *, 8> Ops;
4574 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4575 if (i != FoundIndex)
4576 Ops.push_back(Add->getOperand(i));
4577 const SCEV *Accum = getAddExpr(Ops);
4578
4579 // The runtime checks will not be valid if the step amount is
4580 // varying inside the loop.
4581 if (!isLoopInvariant(Accum, L))
4582 return None;
4583
4584 // *** Part2: Create the predicates
4585
4586 // Analysis was successful: we have a phi-with-cast pattern for which we
4587 // can return an AddRec expression under the following predicates:
4588 //
4589 // P1: A Wrap predicate that guarantees that Trunc(Start) + i*Trunc(Accum)
4590 // fits within the truncated type (does not overflow) for i = 0 to n-1.
4591 // P2: An Equal predicate that guarantees that
4592 // Start = (Ext ix (Trunc iy (Start) to ix) to iy)
4593 // P3: An Equal predicate that guarantees that
4594 // Accum = (Ext ix (Trunc iy (Accum) to ix) to iy)
4595 //
4596 // As we next prove, the above predicates guarantee that:
4597 // Start + i*Accum = (Ext ix (Trunc iy ( Start + i*Accum ) to ix) to iy)
4598 //
4599 //
4600 // More formally, we want to prove that:
4601 // Expr(i+1) = Start + (i+1) * Accum
4602 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4603 //
4604 // Given that:
4605 // 1) Expr(0) = Start
4606 // 2) Expr(1) = Start + Accum
4607 // = (Ext ix (Trunc iy (Start) to ix) to iy) + Accum :: from P2
4608 // 3) Induction hypothesis (step i):
4609 // Expr(i) = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum
4610 //
4611 // Proof:
4612 // Expr(i+1) =
4613 // = Start + (i+1)*Accum
4614 // = (Start + i*Accum) + Accum
4615 // = Expr(i) + Accum
4616 // = (Ext ix (Trunc iy (Expr(i-1)) to ix) to iy) + Accum + Accum
4617 // :: from step i
4618 //
4619 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy) + Accum + Accum
4620 //
4621 // = (Ext ix (Trunc iy (Start + (i-1)*Accum) to ix) to iy)
4622 // + (Ext ix (Trunc iy (Accum) to ix) to iy)
4623 // + Accum :: from P3
4624 //
4625 // = (Ext ix (Trunc iy ((Start + (i-1)*Accum) + Accum) to ix) to iy)
4626 // + Accum :: from P1: Ext(x)+Ext(y)=>Ext(x+y)
4627 //
4628 // = (Ext ix (Trunc iy (Start + i*Accum) to ix) to iy) + Accum
4629 // = (Ext ix (Trunc iy (Expr(i)) to ix) to iy) + Accum
4630 //
4631 // By induction, the same applies to all iterations 1<=i<n:
4632 //
4633
4634 // Create a truncated addrec for which we will add a no overflow check (P1).
4635 const SCEV *StartVal = getSCEV(StartValueV);
4636 const SCEV *PHISCEV =
4637 getAddRecExpr(getTruncateExpr(StartVal, TruncTy),
4638 getTruncateExpr(Accum, TruncTy), L, SCEV::FlagAnyWrap);
4639
4640 // PHISCEV can be either a SCEVConstant or a SCEVAddRecExpr.
4641 // ex: If truncated Accum is 0 and StartVal is a constant, then PHISCEV
4642 // will be constant.
4643 //
4644 // If PHISCEV is a constant, then P1 degenerates into P2 or P3, so we don't
4645 // add P1.
4646 if (const auto *AR = dyn_cast<SCEVAddRecExpr>(PHISCEV)) {
4647 SCEVWrapPredicate::IncrementWrapFlags AddedFlags =
4648 Signed ? SCEVWrapPredicate::IncrementNSSW
4649 : SCEVWrapPredicate::IncrementNUSW;
4650 const SCEVPredicate *AddRecPred = getWrapPredicate(AR, AddedFlags);
4651 Predicates.push_back(AddRecPred);
4652 }
4653
4654 // Create the Equal Predicates P2,P3:
4655
4656 // It is possible that the predicates P2 and/or P3 are computable at
4657 // compile time due to StartVal and/or Accum being constants.
4658 // If either one is, then we can check that now and escape if either P2
4659 // or P3 is false.
4660
4661 // Construct the extended SCEV: (Ext ix (Trunc iy (Expr) to ix) to iy)
4662 // for each of StartVal and Accum
4663 auto getExtendedExpr = [&](const SCEV *Expr,
4664 bool CreateSignExtend) -> const SCEV * {
4665 assert(isLoopInvariant(Expr, L) && "Expr is expected to be invariant")(static_cast <bool> (isLoopInvariant(Expr, L) &&
"Expr is expected to be invariant") ? void (0) : __assert_fail
("isLoopInvariant(Expr, L) && \"Expr is expected to be invariant\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 4665, __extension__ __PRETTY_FUNCTION__))
;
4666 const SCEV *TruncatedExpr = getTruncateExpr(Expr, TruncTy);
4667 const SCEV *ExtendedExpr =
4668 CreateSignExtend ? getSignExtendExpr(TruncatedExpr, Expr->getType())
4669 : getZeroExtendExpr(TruncatedExpr, Expr->getType());
4670 return ExtendedExpr;
4671 };
4672
4673 // Given:
4674 // ExtendedExpr = (Ext ix (Trunc iy (Expr) to ix) to iy
4675 // = getExtendedExpr(Expr)
4676 // Determine whether the predicate P: Expr == ExtendedExpr
4677 // is known to be false at compile time
4678 auto PredIsKnownFalse = [&](const SCEV *Expr,
4679 const SCEV *ExtendedExpr) -> bool {
4680 return Expr != ExtendedExpr &&
4681 isKnownPredicate(ICmpInst::ICMP_NE, Expr, ExtendedExpr);
4682 };
4683
4684 const SCEV *StartExtended = getExtendedExpr(StartVal, Signed);
4685 if (PredIsKnownFalse(StartVal, StartExtended)) {
4686 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)
;
4687 return None;
4688 }
4689
4690 // The Step is always Signed (because the overflow checks are either
4691 // NSSW or NUSW)
4692 const SCEV *AccumExtended = getExtendedExpr(Accum, /*CreateSignExtend=*/true);
4693 if (PredIsKnownFalse(Accum, AccumExtended)) {
4694 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)
;
4695 return None;
4696 }
4697
4698 auto AppendPredicate = [&](const SCEV *Expr,
4699 const SCEV *ExtendedExpr) -> void {
4700 if (Expr != ExtendedExpr &&
4701 !isKnownPredicate(ICmpInst::ICMP_EQ, Expr, ExtendedExpr)) {
4702 const SCEVPredicate *Pred = getEqualPredicate(Expr, ExtendedExpr);
4703 DEBUG (dbgs() << "Added Predicate: " << *Pred)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("scalar-evolution")) { dbgs() << "Added Predicate: " <<
*Pred; } } while (false)
;
4704 Predicates.push_back(Pred);
4705 }
4706 };
4707
4708 AppendPredicate(StartVal, StartExtended);
4709 AppendPredicate(Accum, AccumExtended);
4710
4711 // *** Part3: Predicates are ready. Now go ahead and create the new addrec in
4712 // which the casts had been folded away. The caller can rewrite SymbolicPHI
4713 // into NewAR if it will also add the runtime overflow checks specified in
4714 // Predicates.
4715 auto *NewAR = getAddRecExpr(StartVal, Accum, L, SCEV::FlagAnyWrap);
4716
4717 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> PredRewrite =
4718 std::make_pair(NewAR, Predicates);
4719 // Remember the result of the analysis for this SCEV at this locayyytion.
4720 PredicatedSCEVRewrites[{SymbolicPHI, L}] = PredRewrite;
4721 return PredRewrite;
4722}
4723
4724Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4725ScalarEvolution::createAddRecFromPHIWithCasts(const SCEVUnknown *SymbolicPHI) {
4726 auto *PN = cast<PHINode>(SymbolicPHI->getValue());
4727 const Loop *L = isIntegerLoopHeaderPHI(PN, LI);
4728 if (!L)
4729 return None;
4730
4731 // Check to see if we already analyzed this PHI.
4732 auto I = PredicatedSCEVRewrites.find({SymbolicPHI, L});
4733 if (I != PredicatedSCEVRewrites.end()) {
4734 std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>> Rewrite =
4735 I->second;
4736 // Analysis was done before and failed to create an AddRec:
4737 if (Rewrite.first == SymbolicPHI)
4738 return None;
4739 // Analysis was done before and succeeded to create an AddRec under
4740 // a predicate:
4741 assert(isa<SCEVAddRecExpr>(Rewrite.first) && "Expected an AddRec")(static_cast <bool> (isa<SCEVAddRecExpr>(Rewrite.
first) && "Expected an AddRec") ? void (0) : __assert_fail
("isa<SCEVAddRecExpr>(Rewrite.first) && \"Expected an AddRec\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 4741, __extension__ __PRETTY_FUNCTION__))
;
4742 assert(!(Rewrite.second).empty() && "Expected to find Predicates")(static_cast <bool> (!(Rewrite.second).empty() &&
"Expected to find Predicates") ? void (0) : __assert_fail ("!(Rewrite.second).empty() && \"Expected to find Predicates\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 4742, __extension__ __PRETTY_FUNCTION__))
;
4743 return Rewrite;
4744 }
4745
4746 Optional<std::pair<const SCEV *, SmallVector<const SCEVPredicate *, 3>>>
4747 Rewrite = createAddRecFromPHIWithCastsImpl(SymbolicPHI);
4748
4749 // Record in the cache that the analysis failed
4750 if (!Rewrite) {
4751 SmallVector<const SCEVPredicate *, 3> Predicates;
4752 PredicatedSCEVRewrites[{SymbolicPHI, L}] = {SymbolicPHI, Predicates};
4753 return None;
4754 }
4755
4756 return Rewrite;
4757}
4758
4759// FIXME: This utility is currently required because the Rewriter currently
4760// does not rewrite this expression:
4761// {0, +, (sext ix (trunc iy to ix) to iy)}
4762// into {0, +, %step},
4763// even when the following Equal predicate exists:
4764// "%step == (sext ix (trunc iy to ix) to iy)".
4765bool PredicatedScalarEvolution::areAddRecsEqualWithPreds(
4766 const SCEVAddRecExpr *AR1, const SCEVAddRecExpr *AR2) const {
4767 if (AR1 == AR2)
4768 return true;
4769
4770 auto areExprsEqual = [&](const SCEV *Expr1, const SCEV *Expr2) -> bool {
4771 if (Expr1 != Expr2 && !Preds.implies(SE.getEqualPredicate(Expr1, Expr2)) &&
4772 !Preds.implies(SE.getEqualPredicate(Expr2, Expr1)))
4773 return false;
4774 return true;
4775 };
4776
4777 if (!areExprsEqual(AR1->getStart(), AR2->getStart()) ||
4778 !areExprsEqual(AR1->getStepRecurrence(SE), AR2->getStepRecurrence(SE)))
4779 return false;
4780 return true;
4781}
4782
4783/// A helper function for createAddRecFromPHI to handle simple cases.
4784///
4785/// This function tries to find an AddRec expression for the simplest (yet most
4786/// common) cases: PN = PHI(Start, OP(Self, LoopInvariant)).
4787/// If it fails, createAddRecFromPHI will use a more general, but slow,
4788/// technique for finding the AddRec expression.
4789const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN,
4790 Value *BEValueV,
4791 Value *StartValueV) {
4792 const Loop *L = LI.getLoopFor(PN->getParent());
4793 assert(L && L->getHeader() == PN->getParent())(static_cast <bool> (L && L->getHeader() == PN
->getParent()) ? void (0) : __assert_fail ("L && L->getHeader() == PN->getParent()"
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 4793, __extension__ __PRETTY_FUNCTION__))
;
4794 assert(BEValueV && StartValueV)(static_cast <bool> (BEValueV && StartValueV) ?
void (0) : __assert_fail ("BEValueV && StartValueV",
"/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 4794, __extension__ __PRETTY_FUNCTION__))
;
4795
4796 auto BO = MatchBinaryOp(BEValueV, DT);
4797 if (!BO)
4798 return nullptr;
4799
4800 if (BO->Opcode != Instruction::Add)
4801 return nullptr;
4802
4803 const SCEV *Accum = nullptr;
4804 if (BO->LHS == PN && L->isLoopInvariant(BO->RHS))
4805 Accum = getSCEV(BO->RHS);
4806 else if (BO->RHS == PN && L->isLoopInvariant(BO->LHS))
4807 Accum = getSCEV(BO->LHS);
4808
4809 if (!Accum)
4810 return nullptr;
4811
4812 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4813 if (BO->IsNUW)
4814 Flags = setFlags(Flags, SCEV::FlagNUW);
4815 if (BO->IsNSW)
4816 Flags = setFlags(Flags, SCEV::FlagNSW);
4817
4818 const SCEV *StartVal = getSCEV(StartValueV);
4819 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4820
4821 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
4822
4823 // We can add Flags to the post-inc expression only if we
4824 // know that it is *undefined behavior* for BEValueV to
4825 // overflow.
4826 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
4827 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
4828 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
4829
4830 return PHISCEV;
4831}
4832
4833const SCEV *ScalarEvolution::createAddRecFromPHI(PHINode *PN) {
4834 const Loop *L = LI.getLoopFor(PN->getParent());
4835 if (!L || L->getHeader() != PN->getParent())
4836 return nullptr;
4837
4838 // The loop may have multiple entrances or multiple exits; we can analyze
4839 // this phi as an addrec if it has a unique entry value and a unique
4840 // backedge value.
4841 Value *BEValueV = nullptr, *StartValueV = nullptr;
4842 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
4843 Value *V = PN->getIncomingValue(i);
4844 if (L->contains(PN->getIncomingBlock(i))) {
4845 if (!BEValueV) {
4846 BEValueV = V;
4847 } else if (BEValueV != V) {
4848 BEValueV = nullptr;
4849 break;
4850 }
4851 } else if (!StartValueV) {
4852 StartValueV = V;
4853 } else if (StartValueV != V) {
4854 StartValueV = nullptr;
4855 break;
4856 }
4857 }
4858 if (!BEValueV || !StartValueV)
4859 return nullptr;
4860
4861 assert(ValueExprMap.find_as(PN) == ValueExprMap.end() &&(static_cast <bool> (ValueExprMap.find_as(PN) == ValueExprMap
.end() && "PHI node already processed?") ? void (0) :
__assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 4862, __extension__ __PRETTY_FUNCTION__))
4862 "PHI node already processed?")(static_cast <bool> (ValueExprMap.find_as(PN) == ValueExprMap
.end() && "PHI node already processed?") ? void (0) :
__assert_fail ("ValueExprMap.find_as(PN) == ValueExprMap.end() && \"PHI node already processed?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 4862, __extension__ __PRETTY_FUNCTION__))
;
4863
4864 // First, try to find AddRec expression without creating a fictituos symbolic
4865 // value for PN.
4866 if (auto *S = createSimpleAffineAddRec(PN, BEValueV, StartValueV))
4867 return S;
4868
4869 // Handle PHI node value symbolically.
4870 const SCEV *SymbolicName = getUnknown(PN);
4871 ValueExprMap.insert({SCEVCallbackVH(PN, this), SymbolicName});
4872
4873 // Using this symbolic name for the PHI, analyze the value coming around
4874 // the back-edge.
4875 const SCEV *BEValue = getSCEV(BEValueV);
4876
4877 // NOTE: If BEValue is loop invariant, we know that the PHI node just
4878 // has a special value for the first iteration of the loop.
4879
4880 // If the value coming around the backedge is an add with the symbolic
4881 // value we just inserted, then we found a simple induction variable!
4882 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
4883 // If there is a single occurrence of the symbolic value, replace it
4884 // with a recurrence.
4885 unsigned FoundIndex = Add->getNumOperands();
4886 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4887 if (Add->getOperand(i) == SymbolicName)
4888 if (FoundIndex == e) {
4889 FoundIndex = i;
4890 break;
4891 }
4892
4893 if (FoundIndex != Add->getNumOperands()) {
4894 // Create an add with everything but the specified operand.
4895 SmallVector<const SCEV *, 8> Ops;
4896 for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
4897 if (i != FoundIndex)
4898 Ops.push_back(SCEVBackedgeConditionFolder::rewrite(Add->getOperand(i),
4899 L, *this));
4900 const SCEV *Accum = getAddExpr(Ops);
4901
4902 // This is not a valid addrec if the step amount is varying each
4903 // loop iteration, but is not itself an addrec in this loop.
4904 if (isLoopInvariant(Accum, L) ||
4905 (isa<SCEVAddRecExpr>(Accum) &&
4906 cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
4907 SCEV::NoWrapFlags Flags = SCEV::FlagAnyWrap;
4908
4909 if (auto BO = MatchBinaryOp(BEValueV, DT)) {
4910 if (BO->Opcode == Instruction::Add && BO->LHS == PN) {
4911 if (BO->IsNUW)
4912 Flags = setFlags(Flags, SCEV::FlagNUW);
4913 if (BO->IsNSW)
4914 Flags = setFlags(Flags, SCEV::FlagNSW);
4915 }
4916 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) {
4917 // If the increment is an inbounds GEP, then we know the address
4918 // space cannot be wrapped around. We cannot make any guarantee
4919 // about signed or unsigned overflow because pointers are
4920 // unsigned but we may have a negative index from the base
4921 // pointer. We can guarantee that no unsigned wrap occurs if the
4922 // indices form a positive value.
4923 if (GEP->isInBounds() && GEP->getOperand(0) == PN) {
4924 Flags = setFlags(Flags, SCEV::FlagNW);
4925
4926 const SCEV *Ptr = getSCEV(GEP->getPointerOperand());
4927 if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr)))
4928 Flags = setFlags(Flags, SCEV::FlagNUW);
4929 }
4930
4931 // We cannot transfer nuw and nsw flags from subtraction
4932 // operations -- sub nuw X, Y is not the same as add nuw X, -Y
4933 // for instance.
4934 }
4935
4936 const SCEV *StartVal = getSCEV(StartValueV);
4937 const SCEV *PHISCEV = getAddRecExpr(StartVal, Accum, L, Flags);
4938
4939 // Okay, for the entire analysis of this edge we assumed the PHI
4940 // to be symbolic. We now need to go back and purge all of the
4941 // entries for the scalars that use the symbolic expression.
4942 forgetSymbolicName(PN, SymbolicName);
4943 ValueExprMap[SCEVCallbackVH(PN, this)] = PHISCEV;
4944
4945 // We can add Flags to the post-inc expression only if we
4946 // know that it is *undefined behavior* for BEValueV to
4947 // overflow.
4948 if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
4949 if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
4950 (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
4951
4952 return PHISCEV;
4953 }
4954 }
4955 } else {
4956 // Otherwise, this could be a loop like this:
4957 // i = 0; for (j = 1; ..; ++j) { .... i = j; }
4958 // In this case, j = {1,+,1} and BEValue is j.
4959 // Because the other in-value of i (0) fits the evolution of BEValue
4960 // i really is an addrec evolution.
4961 //
4962 // We can generalize this saying that i is the shifted value of BEValue
4963 // by one iteration:
4964 // PHI(f(0), f({1,+,1})) --> f({0,+,1})
4965 const SCEV *Shifted = SCEVShiftRewriter::rewrite(BEValue, L, *this);
4966 const SCEV *Start = SCEVInitRewriter::rewrite(Shifted, L, *this, false);
4967 if (Shifted != getCouldNotCompute() &&
4968 Start != getCouldNotCompute()) {
4969 const SCEV *StartVal = getSCEV(StartValueV);
4970 if (Start == StartVal) {
4971 // Okay, for the entire analysis of this edge we assumed the PHI
4972 // to be symbolic. We now need to go back and purge all of the
4973 // entries for the scalars that use the symbolic expression.
4974 forgetSymbolicName(PN, SymbolicName);
4975 ValueExprMap[SCEVCallbackVH(PN, this)] = Shifted;
4976 return Shifted;
4977 }
4978 }
4979 }
4980
4981 // Remove the temporary PHI node SCEV that has been inserted while intending
4982 // to create an AddRecExpr for this PHI node. We can not keep this temporary
4983 // as it will prevent later (possibly simpler) SCEV expressions to be added
4984 // to the ValueExprMap.
4985 eraseValueFromMap(PN);
4986
4987 return nullptr;
4988}
4989
4990// Checks if the SCEV S is available at BB. S is considered available at BB
4991// if S can be materialized at BB without introducing a fault.
4992static bool IsAvailableOnEntry(const Loop *L, DominatorTree &DT, const SCEV *S,
4993 BasicBlock *BB) {
4994 struct CheckAvailable {
4995 bool TraversalDone = false;
4996 bool Available = true;
4997
4998 const Loop *L = nullptr; // The loop BB is in (can be nullptr)
4999 BasicBlock *BB = nullptr;
5000 DominatorTree &DT;
5001
5002 CheckAvailable(const Loop *L, BasicBlock *BB, DominatorTree &DT)
5003 : L(L), BB(BB), DT(DT) {}
5004
5005 bool setUnavailable() {
5006 TraversalDone = true;
5007 Available = false;
5008 return false;
5009 }
5010
5011 bool follow(const SCEV *S) {
5012 switch (S->getSCEVType()) {
5013 case scConstant: case scTruncate: case scZeroExtend: case scSignExtend:
5014 case scAddExpr: case scMulExpr: case scUMaxExpr: case scSMaxExpr:
5015 // These expressions are available if their operand(s) is/are.
5016 return true;
5017
5018 case scAddRecExpr: {
5019 // We allow add recurrences that are on the loop BB is in, or some
5020 // outer loop. This guarantees availability because the value of the
5021 // add recurrence at BB is simply the "current" value of the induction
5022 // variable. We can relax this in the future; for instance an add
5023 // recurrence on a sibling dominating loop is also available at BB.
5024 const auto *ARLoop = cast<SCEVAddRecExpr>(S)->getLoop();
5025 if (L && (ARLoop == L || ARLoop->contains(L)))
5026 return true;
5027
5028 return setUnavailable();
5029 }
5030
5031 case scUnknown: {
5032 // For SCEVUnknown, we check for simple dominance.
5033 const auto *SU = cast<SCEVUnknown>(S);
5034 Value *V = SU->getValue();
5035
5036 if (isa<Argument>(V))
5037 return false;
5038
5039 if (isa<Instruction>(V) && DT.dominates(cast<Instruction>(V), BB))
5040 return false;
5041
5042 return setUnavailable();
5043 }
5044
5045 case scUDivExpr:
5046 case scCouldNotCompute:
5047 // We do not try to smart about these at all.
5048 return setUnavailable();
5049 }
5050 llvm_unreachable("switch should be fully covered!")::llvm::llvm_unreachable_internal("switch should be fully covered!"
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5050)
;
5051 }
5052
5053 bool isDone() { return TraversalDone; }
5054 };
5055
5056 CheckAvailable CA(L, BB, DT);
5057 SCEVTraversal<CheckAvailable> ST(CA);
5058
5059 ST.visitAll(S);
5060 return CA.Available;
5061}
5062
5063// Try to match a control flow sequence that branches out at BI and merges back
5064// at Merge into a "C ? LHS : RHS" select pattern. Return true on a successful
5065// match.
5066static bool BrPHIToSelect(DominatorTree &DT, BranchInst *BI, PHINode *Merge,
5067 Value *&C, Value *&LHS, Value *&RHS) {
5068 C = BI->getCondition();
5069
5070 BasicBlockEdge LeftEdge(BI->getParent(), BI->getSuccessor(0));
5071 BasicBlockEdge RightEdge(BI->getParent(), BI->getSuccessor(1));
5072
5073 if (!LeftEdge.isSingleEdge())
5074 return false;
5075
5076 assert(RightEdge.isSingleEdge() && "Follows from LeftEdge.isSingleEdge()")(static_cast <bool> (RightEdge.isSingleEdge() &&
"Follows from LeftEdge.isSingleEdge()") ? void (0) : __assert_fail
("RightEdge.isSingleEdge() && \"Follows from LeftEdge.isSingleEdge()\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5076, __extension__ __PRETTY_FUNCTION__))
;
5077
5078 Use &LeftUse = Merge->getOperandUse(0);
5079 Use &RightUse = Merge->getOperandUse(1);
5080
5081 if (DT.dominates(LeftEdge, LeftUse) && DT.dominates(RightEdge, RightUse)) {
5082 LHS = LeftUse;
5083 RHS = RightUse;
5084 return true;
5085 }
5086
5087 if (DT.dominates(LeftEdge, RightUse) && DT.dominates(RightEdge, LeftUse)) {
5088 LHS = RightUse;
5089 RHS = LeftUse;
5090 return true;
5091 }
5092
5093 return false;
5094}
5095
5096const SCEV *ScalarEvolution::createNodeFromSelectLikePHI(PHINode *PN) {
5097 auto IsReachable =
5098 [&](BasicBlock *BB) { return DT.isReachableFromEntry(BB); };
5099 if (PN->getNumIncomingValues() == 2 && all_of(PN->blocks(), IsReachable)) {
5100 const Loop *L = LI.getLoopFor(PN->getParent());
5101
5102 // We don't want to break LCSSA, even in a SCEV expression tree.
5103 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
5104 if (LI.getLoopFor(PN->getIncomingBlock(i)) != L)
5105 return nullptr;
5106
5107 // Try to match
5108 //
5109 // br %cond, label %left, label %right
5110 // left:
5111 // br label %merge
5112 // right:
5113 // br label %merge
5114 // merge:
5115 // V = phi [ %x, %left ], [ %y, %right ]
5116 //
5117 // as "select %cond, %x, %y"
5118
5119 BasicBlock *IDom = DT[PN->getParent()]->getIDom()->getBlock();
5120 assert(IDom && "At least the entry block should dominate PN")(static_cast <bool> (IDom && "At least the entry block should dominate PN"
) ? void (0) : __assert_fail ("IDom && \"At least the entry block should dominate PN\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5120, __extension__ __PRETTY_FUNCTION__))
;
5121
5122 auto *BI = dyn_cast<BranchInst>(IDom->getTerminator());
5123 Value *Cond = nullptr, *LHS = nullptr, *RHS = nullptr;
5124
5125 if (BI && BI->isConditional() &&
5126 BrPHIToSelect(DT, BI, PN, Cond, LHS, RHS) &&
5127 IsAvailableOnEntry(L, DT, getSCEV(LHS), PN->getParent()) &&
5128 IsAvailableOnEntry(L, DT, getSCEV(RHS), PN->getParent()))
5129 return createNodeForSelectOrPHI(PN, Cond, LHS, RHS);
5130 }
5131
5132 return nullptr;
5133}
5134
5135const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
5136 if (const SCEV *S = createAddRecFromPHI(PN))
5137 return S;
5138
5139 if (const SCEV *S = createNodeFromSelectLikePHI(PN))
5140 return S;
5141
5142 // If the PHI has a single incoming value, follow that value, unless the
5143 // PHI's incoming blocks are in a different loop, in which case doing so
5144 // risks breaking LCSSA form. Instcombine would normally zap these, but
5145 // it doesn't have DominatorTree information, so it may miss cases.
5146 if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC}))
5147 if (LI.replacementPreservesLCSSAForm(PN, V))
5148 return getSCEV(V);
5149
5150 // If it's not a loop phi, we can't handle it yet.
5151 return getUnknown(PN);
5152}
5153
5154const SCEV *ScalarEvolution::createNodeForSelectOrPHI(Instruction *I,
5155 Value *Cond,
5156 Value *TrueVal,
5157 Value *FalseVal) {
5158 // Handle "constant" branch or select. This can occur for instance when a
5159 // loop pass transforms an inner loop and moves on to process the outer loop.
5160 if (auto *CI = dyn_cast<ConstantInt>(Cond))
5161 return getSCEV(CI->isOne() ? TrueVal : FalseVal);
5162
5163 // Try to match some simple smax or umax patterns.
5164 auto *ICI = dyn_cast<ICmpInst>(Cond);
5165 if (!ICI)
5166 return getUnknown(I);
5167
5168 Value *LHS = ICI->getOperand(0);
5169 Value *RHS = ICI->getOperand(1);
5170
5171 switch (ICI->getPredicate()) {
5172 case ICmpInst::ICMP_SLT:
5173 case ICmpInst::ICMP_SLE:
5174 std::swap(LHS, RHS);
5175 LLVM_FALLTHROUGH[[clang::fallthrough]];
5176 case ICmpInst::ICMP_SGT:
5177 case ICmpInst::ICMP_SGE:
5178 // a >s b ? a+x : b+x -> smax(a, b)+x
5179 // a >s b ? b+x : a+x -> smin(a, b)+x
5180 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5181 const SCEV *LS = getNoopOrSignExtend(getSCEV(LHS), I->getType());
5182 const SCEV *RS = getNoopOrSignExtend(getSCEV(RHS), I->getType());
5183 const SCEV *LA = getSCEV(TrueVal);
5184 const SCEV *RA = getSCEV(FalseVal);
5185 const SCEV *LDiff = getMinusSCEV(LA, LS);
5186 const SCEV *RDiff = getMinusSCEV(RA, RS);
5187 if (LDiff == RDiff)
5188 return getAddExpr(getSMaxExpr(LS, RS), LDiff);
5189 LDiff = getMinusSCEV(LA, RS);
5190 RDiff = getMinusSCEV(RA, LS);
5191 if (LDiff == RDiff)
5192 return getAddExpr(getSMinExpr(LS, RS), LDiff);
5193 }
5194 break;
5195 case ICmpInst::ICMP_ULT:
5196 case ICmpInst::ICMP_ULE:
5197 std::swap(LHS, RHS);
5198 LLVM_FALLTHROUGH[[clang::fallthrough]];
5199 case ICmpInst::ICMP_UGT:
5200 case ICmpInst::ICMP_UGE:
5201 // a >u b ? a+x : b+x -> umax(a, b)+x
5202 // a >u b ? b+x : a+x -> umin(a, b)+x
5203 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType())) {
5204 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5205 const SCEV *RS = getNoopOrZeroExtend(getSCEV(RHS), I->getType());
5206 const SCEV *LA = getSCEV(TrueVal);
5207 const SCEV *RA = getSCEV(FalseVal);
5208 const SCEV *LDiff = getMinusSCEV(LA, LS);
5209 const SCEV *RDiff = getMinusSCEV(RA, RS);
5210 if (LDiff == RDiff)
5211 return getAddExpr(getUMaxExpr(LS, RS), LDiff);
5212 LDiff = getMinusSCEV(LA, RS);
5213 RDiff = getMinusSCEV(RA, LS);
5214 if (LDiff == RDiff)
5215 return getAddExpr(getUMinExpr(LS, RS), LDiff);
5216 }
5217 break;
5218 case ICmpInst::ICMP_NE:
5219 // n != 0 ? n+x : 1+x -> umax(n, 1)+x
5220 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5221 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5222 const SCEV *One = getOne(I->getType());
5223 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5224 const SCEV *LA = getSCEV(TrueVal);
5225 const SCEV *RA = getSCEV(FalseVal);
5226 const SCEV *LDiff = getMinusSCEV(LA, LS);
5227 const SCEV *RDiff = getMinusSCEV(RA, One);
5228 if (LDiff == RDiff)
5229 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5230 }
5231 break;
5232 case ICmpInst::ICMP_EQ:
5233 // n == 0 ? 1+x : n+x -> umax(n, 1)+x
5234 if (getTypeSizeInBits(LHS->getType()) <= getTypeSizeInBits(I->getType()) &&
5235 isa<ConstantInt>(RHS) && cast<ConstantInt>(RHS)->isZero()) {
5236 const SCEV *One = getOne(I->getType());
5237 const SCEV *LS = getNoopOrZeroExtend(getSCEV(LHS), I->getType());
5238 const SCEV *LA = getSCEV(TrueVal);
5239 const SCEV *RA = getSCEV(FalseVal);
5240 const SCEV *LDiff = getMinusSCEV(LA, One);
5241 const SCEV *RDiff = getMinusSCEV(RA, LS);
5242 if (LDiff == RDiff)
5243 return getAddExpr(getUMaxExpr(One, LS), LDiff);
5244 }
5245 break;
5246 default:
5247 break;
5248 }
5249
5250 return getUnknown(I);
5251}
5252
5253/// Expand GEP instructions into add and multiply operations. This allows them
5254/// to be analyzed by regular SCEV code.
5255const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
5256 // Don't attempt to analyze GEPs over unsized objects.
5257 if (!GEP->getSourceElementType()->isSized())
5258 return getUnknown(GEP);
5259
5260 SmallVector<const SCEV *, 4> IndexExprs;
5261 for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index)
5262 IndexExprs.push_back(getSCEV(*Index));
5263 return getGEPExpr(GEP, IndexExprs);
5264}
5265
5266uint32_t ScalarEvolution::GetMinTrailingZerosImpl(const SCEV *S) {
5267 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5268 return C->getAPInt().countTrailingZeros();
5269
5270 if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
5271 return std::min(GetMinTrailingZeros(T->getOperand()),
5272 (uint32_t)getTypeSizeInBits(T->getType()));
5273
5274 if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
5275 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5276 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5277 ? getTypeSizeInBits(E->getType())
5278 : OpRes;
5279 }
5280
5281 if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
5282 uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
5283 return OpRes == getTypeSizeInBits(E->getOperand()->getType())
5284 ? getTypeSizeInBits(E->getType())
5285 : OpRes;
5286 }
5287
5288 if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
5289 // The result is the min of all operands results.
5290 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5291 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5292 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5293 return MinOpRes;
5294 }
5295
5296 if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
5297 // The result is the sum of all operands results.
5298 uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
5299 uint32_t BitWidth = getTypeSizeInBits(M->getType());
5300 for (unsigned i = 1, e = M->getNumOperands();
5301 SumOpRes != BitWidth && i != e; ++i)
5302 SumOpRes =
5303 std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)), BitWidth);
5304 return SumOpRes;
5305 }
5306
5307 if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
5308 // The result is the min of all operands results.
5309 uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
5310 for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
5311 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
5312 return MinOpRes;
5313 }
5314
5315 if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
5316 // The result is the min of all operands results.
5317 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5318 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5319 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5320 return MinOpRes;
5321 }
5322
5323 if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
5324 // The result is the min of all operands results.
5325 uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
5326 for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
5327 MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
5328 return MinOpRes;
5329 }
5330
5331 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5332 // For a SCEVUnknown, ask ValueTracking.
5333 KnownBits Known = computeKnownBits(U->getValue(), getDataLayout(), 0, &AC, nullptr, &DT);
5334 return Known.countMinTrailingZeros();
5335 }
5336
5337 // SCEVUDivExpr
5338 return 0;
5339}
5340
5341uint32_t ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
5342 auto I = MinTrailingZerosCache.find(S);
5343 if (I != MinTrailingZerosCache.end())
5344 return I->second;
5345
5346 uint32_t Result = GetMinTrailingZerosImpl(S);
5347 auto InsertPair = MinTrailingZerosCache.insert({S, Result});
5348 assert(InsertPair.second && "Should insert a new key")(static_cast <bool> (InsertPair.second && "Should insert a new key"
) ? void (0) : __assert_fail ("InsertPair.second && \"Should insert a new key\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5348, __extension__ __PRETTY_FUNCTION__))
;
5349 return InsertPair.first->second;
5350}
5351
5352/// Helper method to assign a range to V from metadata present in the IR.
5353static Optional<ConstantRange> GetRangeFromMetadata(Value *V) {
5354 if (Instruction *I = dyn_cast<Instruction>(V))
5355 if (MDNode *MD = I->getMetadata(LLVMContext::MD_range))
5356 return getConstantRangeFromMetadata(*MD);
5357
5358 return None;
5359}
5360
5361/// Determine the range for a particular SCEV. If SignHint is
5362/// HINT_RANGE_UNSIGNED (resp. HINT_RANGE_SIGNED) then getRange prefers ranges
5363/// with a "cleaner" unsigned (resp. signed) representation.
5364const ConstantRange &
5365ScalarEvolution::getRangeRef(const SCEV *S,
5366 ScalarEvolution::RangeSignHint SignHint) {
5367 DenseMap<const SCEV *, ConstantRange> &Cache =
5368 SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED ? UnsignedRanges
5369 : SignedRanges;
5370
5371 // See if we've computed this range already.
5372 DenseMap<const SCEV *, ConstantRange>::iterator I = Cache.find(S);
5373 if (I != Cache.end())
5374 return I->second;
5375
5376 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
5377 return setRange(C, SignHint, ConstantRange(C->getAPInt()));
5378
5379 unsigned BitWidth = getTypeSizeInBits(S->getType());
5380 ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
5381
5382 // If the value has known zeros, the maximum value will have those known zeros
5383 // as well.
5384 uint32_t TZ = GetMinTrailingZeros(S);
5385 if (TZ != 0) {
5386 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED)
5387 ConservativeResult =
5388 ConstantRange(APInt::getMinValue(BitWidth),
5389 APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1);
5390 else
5391 ConservativeResult = ConstantRange(
5392 APInt::getSignedMinValue(BitWidth),
5393 APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1);
5394 }
5395
5396 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
5397 ConstantRange X = getRangeRef(Add->getOperand(0), SignHint);
5398 for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
5399 X = X.add(getRangeRef(Add->getOperand(i), SignHint));
5400 return setRange(Add, SignHint, ConservativeResult.intersectWith(X));
5401 }
5402
5403 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
5404 ConstantRange X = getRangeRef(Mul->getOperand(0), SignHint);
5405 for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
5406 X = X.multiply(getRangeRef(Mul->getOperand(i), SignHint));
5407 return setRange(Mul, SignHint, ConservativeResult.intersectWith(X));
5408 }
5409
5410 if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
5411 ConstantRange X = getRangeRef(SMax->getOperand(0), SignHint);
5412 for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
5413 X = X.smax(getRangeRef(SMax->getOperand(i), SignHint));
5414 return setRange(SMax, SignHint, ConservativeResult.intersectWith(X));
5415 }
5416
5417 if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
5418 ConstantRange X = getRangeRef(UMax->getOperand(0), SignHint);
5419 for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
5420 X = X.umax(getRangeRef(UMax->getOperand(i), SignHint));
5421 return setRange(UMax, SignHint, ConservativeResult.intersectWith(X));
5422 }
5423
5424 if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
5425 ConstantRange X = getRangeRef(UDiv->getLHS(), SignHint);
5426 ConstantRange Y = getRangeRef(UDiv->getRHS(), SignHint);
5427 return setRange(UDiv, SignHint,
5428 ConservativeResult.intersectWith(X.udiv(Y)));
5429 }
5430
5431 if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
5432 ConstantRange X = getRangeRef(ZExt->getOperand(), SignHint);
5433 return setRange(ZExt, SignHint,
5434 ConservativeResult.intersectWith(X.zeroExtend(BitWidth)));
5435 }
5436
5437 if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
5438 ConstantRange X = getRangeRef(SExt->getOperand(), SignHint);
5439 return setRange(SExt, SignHint,
5440 ConservativeResult.intersectWith(X.signExtend(BitWidth)));
5441 }
5442
5443 if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
5444 ConstantRange X = getRangeRef(Trunc->getOperand(), SignHint);
5445 return setRange(Trunc, SignHint,
5446 ConservativeResult.intersectWith(X.truncate(BitWidth)));
5447 }
5448
5449 if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
5450 // If there's no unsigned wrap, the value will never be less than its
5451 // initial value.
5452 if (AddRec->hasNoUnsignedWrap())
5453 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart()))
5454 if (!C->getValue()->isZero())
5455 ConservativeResult = ConservativeResult.intersectWith(
5456 ConstantRange(C->getAPInt(), APInt(BitWidth, 0)));
5457
5458 // If there's no signed wrap, and all the operands have the same sign or
5459 // zero, the value won't ever change sign.
5460 if (AddRec->hasNoSignedWrap()) {
5461 bool AllNonNeg = true;
5462 bool AllNonPos = true;
5463 for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
5464 if (!isKnownNonNegative(AddRec->getOperand(i))) AllNonNeg = false;
5465 if (!isKnownNonPositive(AddRec->getOperand(i))) AllNonPos = false;
5466 }
5467 if (AllNonNeg)
5468 ConservativeResult = ConservativeResult.intersectWith(
5469 ConstantRange(APInt(BitWidth, 0),
5470 APInt::getSignedMinValue(BitWidth)));
5471 else if (AllNonPos)
5472 ConservativeResult = ConservativeResult.intersectWith(
5473 ConstantRange(APInt::getSignedMinValue(BitWidth),
5474 APInt(BitWidth, 1)));
5475 }
5476
5477 // TODO: non-affine addrec
5478 if (AddRec->isAffine()) {
5479 const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
5480 if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
5481 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
5482 auto RangeFromAffine = getRangeForAffineAR(
5483 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
5484 BitWidth);
5485 if (!RangeFromAffine.isFullSet())
5486 ConservativeResult =
5487 ConservativeResult.intersectWith(RangeFromAffine);
5488
5489 auto RangeFromFactoring = getRangeViaFactoring(
5490 AddRec->getStart(), AddRec->getStepRecurrence(*this), MaxBECount,
5491 BitWidth);
5492 if (!RangeFromFactoring.isFullSet())
5493 ConservativeResult =
5494 ConservativeResult.intersectWith(RangeFromFactoring);
5495 }
5496 }
5497
5498 return setRange(AddRec, SignHint, std::move(ConservativeResult));
5499 }
5500
5501 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
5502 // Check if the IR explicitly contains !range metadata.
5503 Optional<ConstantRange> MDRange = GetRangeFromMetadata(U->getValue());
5504 if (MDRange.hasValue())
5505 ConservativeResult = ConservativeResult.intersectWith(MDRange.getValue());
5506
5507 // Split here to avoid paying the compile-time cost of calling both
5508 // computeKnownBits and ComputeNumSignBits. This restriction can be lifted
5509 // if needed.
5510 const DataLayout &DL = getDataLayout();
5511 if (SignHint == ScalarEvolution::HINT_RANGE_UNSIGNED) {
5512 // For a SCEVUnknown, ask ValueTracking.
5513 KnownBits Known = computeKnownBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
5514 if (Known.One != ~Known.Zero + 1)
5515 ConservativeResult =
5516 ConservativeResult.intersectWith(ConstantRange(Known.One,
5517 ~Known.Zero + 1));
5518 } else {
5519 assert(SignHint == ScalarEvolution::HINT_RANGE_SIGNED &&(static_cast <bool> (SignHint == ScalarEvolution::HINT_RANGE_SIGNED
&& "generalize as needed!") ? void (0) : __assert_fail
("SignHint == ScalarEvolution::HINT_RANGE_SIGNED && \"generalize as needed!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5520, __extension__ __PRETTY_FUNCTION__))
5520 "generalize as needed!")(static_cast <bool> (SignHint == ScalarEvolution::HINT_RANGE_SIGNED
&& "generalize as needed!") ? void (0) : __assert_fail
("SignHint == ScalarEvolution::HINT_RANGE_SIGNED && \"generalize as needed!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5520, __extension__ __PRETTY_FUNCTION__))
;
5521 unsigned NS = ComputeNumSignBits(U->getValue(), DL, 0, &AC, nullptr, &DT);
5522 if (NS > 1)
5523 ConservativeResult = ConservativeResult.intersectWith(
5524 ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
5525 APInt::getSignedMaxValue(BitWidth).ashr(NS - 1) + 1));
5526 }
5527
5528 // A range of Phi is a subset of union of all ranges of its input.
5529 if (const PHINode *Phi = dyn_cast<PHINode>(U->getValue())) {
5530 // Make sure that we do not run over cycled Phis.
5531 if (PendingPhiRanges.insert(Phi).second) {
5532 ConstantRange RangeFromOps(BitWidth, /*isFullSet=*/false);
5533 for (auto &Op : Phi->operands()) {
5534 auto OpRange = getRangeRef(getSCEV(Op), SignHint);
5535 RangeFromOps = RangeFromOps.unionWith(OpRange);
5536 // No point to continue if we already have a full set.
5537 if (RangeFromOps.isFullSet())
5538 break;
5539 }
5540 ConservativeResult = ConservativeResult.intersectWith(RangeFromOps);
5541 bool Erased = PendingPhiRanges.erase(Phi);
5542 assert(Erased && "Failed to erase Phi properly?")(static_cast <bool> (Erased && "Failed to erase Phi properly?"
) ? void (0) : __assert_fail ("Erased && \"Failed to erase Phi properly?\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5542, __extension__ __PRETTY_FUNCTION__))
;
5543 (void) Erased;
5544 }
5545 }
5546
5547 return setRange(U, SignHint, std::move(ConservativeResult));
5548 }
5549
5550 return setRange(S, SignHint, std::move(ConservativeResult));
5551}
5552
5553// Given a StartRange, Step and MaxBECount for an expression compute a range of
5554// values that the expression can take. Initially, the expression has a value
5555// from StartRange and then is changed by Step up to MaxBECount times. Signed
5556// argument defines if we treat Step as signed or unsigned.
5557static ConstantRange getRangeForAffineARHelper(APInt Step,
5558 const ConstantRange &StartRange,
5559 const APInt &MaxBECount,
5560 unsigned BitWidth, bool Signed) {
5561 // If either Step or MaxBECount is 0, then the expression won't change, and we
5562 // just need to return the initial range.
5563 if (Step == 0 || MaxBECount == 0)
5564 return StartRange;
5565
5566 // If we don't know anything about the initial value (i.e. StartRange is
5567 // FullRange), then we don't know anything about the final range either.
5568 // Return FullRange.
5569 if (StartRange.isFullSet())
5570 return ConstantRange(BitWidth, /* isFullSet = */ true);
5571
5572 // If Step is signed and negative, then we use its absolute value, but we also
5573 // note that we're moving in the opposite direction.
5574 bool Descending = Signed && Step.isNegative();
5575
5576 if (Signed)
5577 // This is correct even for INT_SMIN. Let's look at i8 to illustrate this:
5578 // abs(INT_SMIN) = abs(-128) = abs(0x80) = -0x80 = 0x80 = 128.
5579 // This equations hold true due to the well-defined wrap-around behavior of
5580 // APInt.
5581 Step = Step.abs();
5582
5583 // Check if Offset is more than full span of BitWidth. If it is, the
5584 // expression is guaranteed to overflow.
5585 if (APInt::getMaxValue(StartRange.getBitWidth()).udiv(Step).ult(MaxBECount))
5586 return ConstantRange(BitWidth, /* isFullSet = */ true);
5587
5588 // Offset is by how much the expression can change. Checks above guarantee no
5589 // overflow here.
5590 APInt Offset = Step * MaxBECount;
5591
5592 // Minimum value of the final range will match the minimal value of StartRange
5593 // if the expression is increasing and will be decreased by Offset otherwise.
5594 // Maximum value of the final range will match the maximal value of StartRange
5595 // if the expression is decreasing and will be increased by Offset otherwise.
5596 APInt StartLower = StartRange.getLower();
5597 APInt StartUpper = StartRange.getUpper() - 1;
5598 APInt MovedBoundary = Descending ? (StartLower - std::move(Offset))
5599 : (StartUpper + std::move(Offset));
5600
5601 // It's possible that the new minimum/maximum value will fall into the initial
5602 // range (due to wrap around). This means that the expression can take any
5603 // value in this bitwidth, and we have to return full range.
5604 if (StartRange.contains(MovedBoundary))
5605 return ConstantRange(BitWidth, /* isFullSet = */ true);
5606
5607 APInt NewLower =
5608 Descending ? std::move(MovedBoundary) : std::move(StartLower);
5609 APInt NewUpper =
5610 Descending ? std::move(StartUpper) : std::move(MovedBoundary);
5611 NewUpper += 1;
5612
5613 // If we end up with full range, return a proper full range.
5614 if (NewLower == NewUpper)
5615 return ConstantRange(BitWidth, /* isFullSet = */ true);
5616
5617 // No overflow detected, return [StartLower, StartUpper + Offset + 1) range.
5618 return ConstantRange(std::move(NewLower), std::move(NewUpper));
5619}
5620
5621ConstantRange ScalarEvolution::getRangeForAffineAR(const SCEV *Start,
5622 const SCEV *Step,
5623 const SCEV *MaxBECount,
5624 unsigned BitWidth) {
5625 assert(!isa<SCEVCouldNotCompute>(MaxBECount) &&(static_cast <bool> (!isa<SCEVCouldNotCompute>(MaxBECount
) && getTypeSizeInBits(MaxBECount->getType()) <=
BitWidth && "Precondition!") ? void (0) : __assert_fail
("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5627, __extension__ __PRETTY_FUNCTION__))
5626 getTypeSizeInBits(MaxBECount->getType()) <= BitWidth &&(static_cast <bool> (!isa<SCEVCouldNotCompute>(MaxBECount
) && getTypeSizeInBits(MaxBECount->getType()) <=
BitWidth && "Precondition!") ? void (0) : __assert_fail
("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5627, __extension__ __PRETTY_FUNCTION__))
5627 "Precondition!")(static_cast <bool> (!isa<SCEVCouldNotCompute>(MaxBECount
) && getTypeSizeInBits(MaxBECount->getType()) <=
BitWidth && "Precondition!") ? void (0) : __assert_fail
("!isa<SCEVCouldNotCompute>(MaxBECount) && getTypeSizeInBits(MaxBECount->getType()) <= BitWidth && \"Precondition!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5627, __extension__ __PRETTY_FUNCTION__))
;
5628
5629 MaxBECount = getNoopOrZeroExtend(MaxBECount, Start->getType());
5630 APInt MaxBECountValue = getUnsignedRangeMax(MaxBECount);
5631
5632 // First, consider step signed.
5633 ConstantRange StartSRange = getSignedRange(Start);
5634 ConstantRange StepSRange = getSignedRange(Step);
5635
5636 // If Step can be both positive and negative, we need to find ranges for the
5637 // maximum absolute step values in both directions and union them.
5638 ConstantRange SR =
5639 getRangeForAffineARHelper(StepSRange.getSignedMin(), StartSRange,
5640 MaxBECountValue, BitWidth, /* Signed = */ true);
5641 SR = SR.unionWith(getRangeForAffineARHelper(StepSRange.getSignedMax(),
5642 StartSRange, MaxBECountValue,
5643 BitWidth, /* Signed = */ true));
5644
5645 // Next, consider step unsigned.
5646 ConstantRange UR = getRangeForAffineARHelper(
5647 getUnsignedRangeMax(Step), getUnsignedRange(Start),
5648 MaxBECountValue, BitWidth, /* Signed = */ false);
5649
5650 // Finally, intersect signed and unsigned ranges.
5651 return SR.intersectWith(UR);
5652}
5653
5654ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
5655 const SCEV *Step,
5656 const SCEV *MaxBECount,
5657 unsigned BitWidth) {
5658 // RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q})
5659 // == RangeOf({A,+,P}) union RangeOf({B,+,Q})
5660
5661 struct SelectPattern {
5662 Value *Condition = nullptr;
5663 APInt TrueValue;
5664 APInt FalseValue;
5665
5666 explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth,
5667 const SCEV *S) {
5668 Optional<unsigned> CastOp;
5669 APInt Offset(BitWidth, 0);
5670
5671 assert(SE.getTypeSizeInBits(S->getType()) == BitWidth &&(static_cast <bool> (SE.getTypeSizeInBits(S->getType
()) == BitWidth && "Should be!") ? void (0) : __assert_fail
("SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5672, __extension__ __PRETTY_FUNCTION__))
5672 "Should be!")(static_cast <bool> (SE.getTypeSizeInBits(S->getType
()) == BitWidth && "Should be!") ? void (0) : __assert_fail
("SE.getTypeSizeInBits(S->getType()) == BitWidth && \"Should be!\""
, "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5672, __extension__ __PRETTY_FUNCTION__))
;
5673
5674 // Peel off a constant offset:
5675 if (auto *SA = dyn_cast<SCEVAddExpr>(S)) {
5676 // In the future we could consider being smarter here and handle
5677 // {Start+Step,+,Step} too.
5678 if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
5679 return;
5680
5681 Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
5682 S = SA->getOperand(1);
5683 }
5684
5685 // Peel off a cast operation
5686 if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) {
5687 CastOp = SCast->getSCEVType();
5688 S = SCast->getOperand();
5689 }
5690
5691 using namespace llvm::PatternMatch;
5692
5693 auto *SU = dyn_cast<SCEVUnknown>(S);
5694 const APInt *TrueVal, *FalseVal;
5695 if (!SU ||
5696 !match(SU->getValue(), m_Select(m_Value(Condition), m_APInt(TrueVal),
5697 m_APInt(FalseVal)))) {
5698 Condition = nullptr;
5699 return;
5700 }
5701
5702 TrueValue = *TrueVal;
5703 FalseValue = *FalseVal;
5704
5705 // Re-apply the cast we peeled off earlier
5706 if (CastOp.hasValue())
5707 switch (*CastOp) {
5708 default:
5709 llvm_unreachable("Unknown SCEV cast type!")::llvm::llvm_unreachable_internal("Unknown SCEV cast type!", "/build/llvm-toolchain-snapshot-7~svn329677/lib/Analysis/ScalarEvolution.cpp"
, 5709)
;
5710
5711 case scTruncate:
5712 TrueValue = TrueValue.trunc(BitWidth);
5713 FalseValue = FalseValue.trunc(BitWidth);
5714 break;
5715 case scZeroExtend:
5716 TrueValue = TrueValue.zext(B