Bug Summary

File:lib/Transforms/Scalar/LoopStrengthReduce.cpp
Warning:line 5144, column 16
Called C++ object pointer is null

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 LoopStrengthReduce.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -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 -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -mframe-pointer=none -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-10/lib/clang/10.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-10~svn374877/build-llvm/lib/Transforms/Scalar -I /build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar -I /build/llvm-toolchain-snapshot-10~svn374877/build-llvm/include -I /build/llvm-toolchain-snapshot-10~svn374877/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-10/lib/clang/10.0.0/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++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-10~svn374877/build-llvm/lib/Transforms/Scalar -fdebug-prefix-map=/build/llvm-toolchain-snapshot-10~svn374877=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2019-10-15-233810-7101-1 -x c++ /build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp
1//===- LoopStrengthReduce.cpp - Strength Reduce IVs in Loops --------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This transformation analyzes and transforms the induction variables (and
10// computations derived from them) into forms suitable for efficient execution
11// on the target.
12//
13// This pass performs a strength reduction on array references inside loops that
14// have as one or more of their components the loop induction variable, it
15// rewrites expressions to take advantage of scaled-index addressing modes
16// available on the target, and it performs a variety of other optimizations
17// related to loop induction variables.
18//
19// Terminology note: this code has a lot of handling for "post-increment" or
20// "post-inc" users. This is not talking about post-increment addressing modes;
21// it is instead talking about code like this:
22//
23// %i = phi [ 0, %entry ], [ %i.next, %latch ]
24// ...
25// %i.next = add %i, 1
26// %c = icmp eq %i.next, %n
27//
28// The SCEV for %i is {0,+,1}<%L>. The SCEV for %i.next is {1,+,1}<%L>, however
29// it's useful to think about these as the same register, with some uses using
30// the value of the register before the add and some using it after. In this
31// example, the icmp is a post-increment user, since it uses %i.next, which is
32// the value of the induction variable after the increment. The other common
33// case of post-increment users is users outside the loop.
34//
35// TODO: More sophistication in the way Formulae are generated and filtered.
36//
37// TODO: Handle multiple loops at a time.
38//
39// TODO: Should the addressing mode BaseGV be changed to a ConstantExpr instead
40// of a GlobalValue?
41//
42// TODO: When truncation is free, truncate ICmp users' operands to make it a
43// smaller encoding (on x86 at least).
44//
45// TODO: When a negated register is used by an add (such as in a list of
46// multiple base registers, or as the increment expression in an addrec),
47// we may not actually need both reg and (-1 * reg) in registers; the
48// negation can be implemented by using a sub instead of an add. The
49// lack of support for taking this into consideration when making
50// register pressure decisions is partly worked around by the "Special"
51// use kind.
52//
53//===----------------------------------------------------------------------===//
54
55#include "llvm/Transforms/Scalar/LoopStrengthReduce.h"
56#include "llvm/ADT/APInt.h"
57#include "llvm/ADT/DenseMap.h"
58#include "llvm/ADT/DenseSet.h"
59#include "llvm/ADT/Hashing.h"
60#include "llvm/ADT/PointerIntPair.h"
61#include "llvm/ADT/STLExtras.h"
62#include "llvm/ADT/SetVector.h"
63#include "llvm/ADT/SmallBitVector.h"
64#include "llvm/ADT/SmallPtrSet.h"
65#include "llvm/ADT/SmallSet.h"
66#include "llvm/ADT/SmallVector.h"
67#include "llvm/ADT/iterator_range.h"
68#include "llvm/Analysis/IVUsers.h"
69#include "llvm/Analysis/LoopAnalysisManager.h"
70#include "llvm/Analysis/LoopInfo.h"
71#include "llvm/Analysis/LoopPass.h"
72#include "llvm/Analysis/ScalarEvolution.h"
73#include "llvm/Analysis/ScalarEvolutionExpander.h"
74#include "llvm/Analysis/ScalarEvolutionExpressions.h"
75#include "llvm/Analysis/ScalarEvolutionNormalization.h"
76#include "llvm/Analysis/TargetTransformInfo.h"
77#include "llvm/Transforms/Utils/Local.h"
78#include "llvm/Config/llvm-config.h"
79#include "llvm/IR/BasicBlock.h"
80#include "llvm/IR/Constant.h"
81#include "llvm/IR/Constants.h"
82#include "llvm/IR/DerivedTypes.h"
83#include "llvm/IR/Dominators.h"
84#include "llvm/IR/GlobalValue.h"
85#include "llvm/IR/IRBuilder.h"
86#include "llvm/IR/InstrTypes.h"
87#include "llvm/IR/Instruction.h"
88#include "llvm/IR/Instructions.h"
89#include "llvm/IR/IntrinsicInst.h"
90#include "llvm/IR/Intrinsics.h"
91#include "llvm/IR/Module.h"
92#include "llvm/IR/OperandTraits.h"
93#include "llvm/IR/Operator.h"
94#include "llvm/IR/PassManager.h"
95#include "llvm/IR/Type.h"
96#include "llvm/IR/Use.h"
97#include "llvm/IR/User.h"
98#include "llvm/IR/Value.h"
99#include "llvm/IR/ValueHandle.h"
100#include "llvm/Pass.h"
101#include "llvm/Support/Casting.h"
102#include "llvm/Support/CommandLine.h"
103#include "llvm/Support/Compiler.h"
104#include "llvm/Support/Debug.h"
105#include "llvm/Support/ErrorHandling.h"
106#include "llvm/Support/MathExtras.h"
107#include "llvm/Support/raw_ostream.h"
108#include "llvm/Transforms/Scalar.h"
109#include "llvm/Transforms/Utils.h"
110#include "llvm/Transforms/Utils/BasicBlockUtils.h"
111#include <algorithm>
112#include <cassert>
113#include <cstddef>
114#include <cstdint>
115#include <cstdlib>
116#include <iterator>
117#include <limits>
118#include <numeric>
119#include <map>
120#include <utility>
121
122using namespace llvm;
123
124#define DEBUG_TYPE"loop-reduce" "loop-reduce"
125
126/// MaxIVUsers is an arbitrary threshold that provides an early opportunity for
127/// bail out. This threshold is far beyond the number of users that LSR can
128/// conceivably solve, so it should not affect generated code, but catches the
129/// worst cases before LSR burns too much compile time and stack space.
130static const unsigned MaxIVUsers = 200;
131
132// Temporary flag to cleanup congruent phis after LSR phi expansion.
133// It's currently disabled until we can determine whether it's truly useful or
134// not. The flag should be removed after the v3.0 release.
135// This is now needed for ivchains.
136static cl::opt<bool> EnablePhiElim(
137 "enable-lsr-phielim", cl::Hidden, cl::init(true),
138 cl::desc("Enable LSR phi elimination"));
139
140// The flag adds instruction count to solutions cost comparision.
141static cl::opt<bool> InsnsCost(
142 "lsr-insns-cost", cl::Hidden, cl::init(true),
143 cl::desc("Add instruction count to a LSR cost model"));
144
145// Flag to choose how to narrow complex lsr solution
146static cl::opt<bool> LSRExpNarrow(
147 "lsr-exp-narrow", cl::Hidden, cl::init(false),
148 cl::desc("Narrow LSR complex solution using"
149 " expectation of registers number"));
150
151// Flag to narrow search space by filtering non-optimal formulae with
152// the same ScaledReg and Scale.
153static cl::opt<bool> FilterSameScaledReg(
154 "lsr-filter-same-scaled-reg", cl::Hidden, cl::init(true),
155 cl::desc("Narrow LSR search space by filtering non-optimal formulae"
156 " with the same ScaledReg and Scale"));
157
158static cl::opt<bool> EnableBackedgeIndexing(
159 "lsr-backedge-indexing", cl::Hidden, cl::init(true),
160 cl::desc("Enable the generation of cross iteration indexed memops"));
161
162static cl::opt<unsigned> ComplexityLimit(
163 "lsr-complexity-limit", cl::Hidden,
164 cl::init(std::numeric_limits<uint16_t>::max()),
165 cl::desc("LSR search space complexity limit"));
166
167static cl::opt<unsigned> SetupCostDepthLimit(
168 "lsr-setupcost-depth-limit", cl::Hidden, cl::init(7),
169 cl::desc("The limit on recursion depth for LSRs setup cost"));
170
171#ifndef NDEBUG
172// Stress test IV chain generation.
173static cl::opt<bool> StressIVChain(
174 "stress-ivchain", cl::Hidden, cl::init(false),
175 cl::desc("Stress test LSR IV chains"));
176#else
177static bool StressIVChain = false;
178#endif
179
180namespace {
181
182struct MemAccessTy {
183 /// Used in situations where the accessed memory type is unknown.
184 static const unsigned UnknownAddressSpace =
185 std::numeric_limits<unsigned>::max();
186
187 Type *MemTy = nullptr;
188 unsigned AddrSpace = UnknownAddressSpace;
189
190 MemAccessTy() = default;
191 MemAccessTy(Type *Ty, unsigned AS) : MemTy(Ty), AddrSpace(AS) {}
192
193 bool operator==(MemAccessTy Other) const {
194 return MemTy == Other.MemTy && AddrSpace == Other.AddrSpace;
195 }
196
197 bool operator!=(MemAccessTy Other) const { return !(*this == Other); }
198
199 static MemAccessTy getUnknown(LLVMContext &Ctx,
200 unsigned AS = UnknownAddressSpace) {
201 return MemAccessTy(Type::getVoidTy(Ctx), AS);
202 }
203
204 Type *getType() { return MemTy; }
205};
206
207/// This class holds data which is used to order reuse candidates.
208class RegSortData {
209public:
210 /// This represents the set of LSRUse indices which reference
211 /// a particular register.
212 SmallBitVector UsedByIndices;
213
214 void print(raw_ostream &OS) const;
215 void dump() const;
216};
217
218} // end anonymous namespace
219
220#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
221void RegSortData::print(raw_ostream &OS) const {
222 OS << "[NumUses=" << UsedByIndices.count() << ']';
223}
224
225LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void RegSortData::dump() const {
226 print(errs()); errs() << '\n';
227}
228#endif
229
230namespace {
231
232/// Map register candidates to information about how they are used.
233class RegUseTracker {
234 using RegUsesTy = DenseMap<const SCEV *, RegSortData>;
235
236 RegUsesTy RegUsesMap;
237 SmallVector<const SCEV *, 16> RegSequence;
238
239public:
240 void countRegister(const SCEV *Reg, size_t LUIdx);
241 void dropRegister(const SCEV *Reg, size_t LUIdx);
242 void swapAndDropUse(size_t LUIdx, size_t LastLUIdx);
243
244 bool isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const;
245
246 const SmallBitVector &getUsedByIndices(const SCEV *Reg) const;
247
248 void clear();
249
250 using iterator = SmallVectorImpl<const SCEV *>::iterator;
251 using const_iterator = SmallVectorImpl<const SCEV *>::const_iterator;
252
253 iterator begin() { return RegSequence.begin(); }
254 iterator end() { return RegSequence.end(); }
255 const_iterator begin() const { return RegSequence.begin(); }
256 const_iterator end() const { return RegSequence.end(); }
257};
258
259} // end anonymous namespace
260
261void
262RegUseTracker::countRegister(const SCEV *Reg, size_t LUIdx) {
263 std::pair<RegUsesTy::iterator, bool> Pair =
264 RegUsesMap.insert(std::make_pair(Reg, RegSortData()));
265 RegSortData &RSD = Pair.first->second;
266 if (Pair.second)
267 RegSequence.push_back(Reg);
268 RSD.UsedByIndices.resize(std::max(RSD.UsedByIndices.size(), LUIdx + 1));
269 RSD.UsedByIndices.set(LUIdx);
270}
271
272void
273RegUseTracker::dropRegister(const SCEV *Reg, size_t LUIdx) {
274 RegUsesTy::iterator It = RegUsesMap.find(Reg);
275 assert(It != RegUsesMap.end())((It != RegUsesMap.end()) ? static_cast<void> (0) : __assert_fail
("It != RegUsesMap.end()", "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 275, __PRETTY_FUNCTION__))
;
276 RegSortData &RSD = It->second;
277 assert(RSD.UsedByIndices.size() > LUIdx)((RSD.UsedByIndices.size() > LUIdx) ? static_cast<void>
(0) : __assert_fail ("RSD.UsedByIndices.size() > LUIdx", "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 277, __PRETTY_FUNCTION__))
;
278 RSD.UsedByIndices.reset(LUIdx);
279}
280
281void
282RegUseTracker::swapAndDropUse(size_t LUIdx, size_t LastLUIdx) {
283 assert(LUIdx <= LastLUIdx)((LUIdx <= LastLUIdx) ? static_cast<void> (0) : __assert_fail
("LUIdx <= LastLUIdx", "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 283, __PRETTY_FUNCTION__))
;
284
285 // Update RegUses. The data structure is not optimized for this purpose;
286 // we must iterate through it and update each of the bit vectors.
287 for (auto &Pair : RegUsesMap) {
288 SmallBitVector &UsedByIndices = Pair.second.UsedByIndices;
289 if (LUIdx < UsedByIndices.size())
290 UsedByIndices[LUIdx] =
291 LastLUIdx < UsedByIndices.size() ? UsedByIndices[LastLUIdx] : false;
292 UsedByIndices.resize(std::min(UsedByIndices.size(), LastLUIdx));
293 }
294}
295
296bool
297RegUseTracker::isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const {
298 RegUsesTy::const_iterator I = RegUsesMap.find(Reg);
299 if (I == RegUsesMap.end())
300 return false;
301 const SmallBitVector &UsedByIndices = I->second.UsedByIndices;
302 int i = UsedByIndices.find_first();
303 if (i == -1) return false;
304 if ((size_t)i != LUIdx) return true;
305 return UsedByIndices.find_next(i) != -1;
306}
307
308const SmallBitVector &RegUseTracker::getUsedByIndices(const SCEV *Reg) const {
309 RegUsesTy::const_iterator I = RegUsesMap.find(Reg);
310 assert(I != RegUsesMap.end() && "Unknown register!")((I != RegUsesMap.end() && "Unknown register!") ? static_cast
<void> (0) : __assert_fail ("I != RegUsesMap.end() && \"Unknown register!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 310, __PRETTY_FUNCTION__))
;
311 return I->second.UsedByIndices;
312}
313
314void RegUseTracker::clear() {
315 RegUsesMap.clear();
316 RegSequence.clear();
317}
318
319namespace {
320
321/// This class holds information that describes a formula for computing
322/// satisfying a use. It may include broken-out immediates and scaled registers.
323struct Formula {
324 /// Global base address used for complex addressing.
325 GlobalValue *BaseGV = nullptr;
326
327 /// Base offset for complex addressing.
328 int64_t BaseOffset = 0;
329
330 /// Whether any complex addressing has a base register.
331 bool HasBaseReg = false;
332
333 /// The scale of any complex addressing.
334 int64_t Scale = 0;
335
336 /// The list of "base" registers for this use. When this is non-empty. The
337 /// canonical representation of a formula is
338 /// 1. BaseRegs.size > 1 implies ScaledReg != NULL and
339 /// 2. ScaledReg != NULL implies Scale != 1 || !BaseRegs.empty().
340 /// 3. The reg containing recurrent expr related with currect loop in the
341 /// formula should be put in the ScaledReg.
342 /// #1 enforces that the scaled register is always used when at least two
343 /// registers are needed by the formula: e.g., reg1 + reg2 is reg1 + 1 * reg2.
344 /// #2 enforces that 1 * reg is reg.
345 /// #3 ensures invariant regs with respect to current loop can be combined
346 /// together in LSR codegen.
347 /// This invariant can be temporarily broken while building a formula.
348 /// However, every formula inserted into the LSRInstance must be in canonical
349 /// form.
350 SmallVector<const SCEV *, 4> BaseRegs;
351
352 /// The 'scaled' register for this use. This should be non-null when Scale is
353 /// not zero.
354 const SCEV *ScaledReg = nullptr;
355
356 /// An additional constant offset which added near the use. This requires a
357 /// temporary register, but the offset itself can live in an add immediate
358 /// field rather than a register.
359 int64_t UnfoldedOffset = 0;
360
361 Formula() = default;
362
363 void initialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE);
364
365 bool isCanonical(const Loop &L) const;
366
367 void canonicalize(const Loop &L);
368
369 bool unscale();
370
371 bool hasZeroEnd() const;
372
373 size_t getNumRegs() const;
374 Type *getType() const;
375
376 void deleteBaseReg(const SCEV *&S);
377
378 bool referencesReg(const SCEV *S) const;
379 bool hasRegsUsedByUsesOtherThan(size_t LUIdx,
380 const RegUseTracker &RegUses) const;
381
382 void print(raw_ostream &OS) const;
383 void dump() const;
384};
385
386} // end anonymous namespace
387
388/// Recursion helper for initialMatch.
389static void DoInitialMatch(const SCEV *S, Loop *L,
390 SmallVectorImpl<const SCEV *> &Good,
391 SmallVectorImpl<const SCEV *> &Bad,
392 ScalarEvolution &SE) {
393 // Collect expressions which properly dominate the loop header.
394 if (SE.properlyDominates(S, L->getHeader())) {
395 Good.push_back(S);
396 return;
397 }
398
399 // Look at add operands.
400 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
401 for (const SCEV *S : Add->operands())
402 DoInitialMatch(S, L, Good, Bad, SE);
403 return;
404 }
405
406 // Look at addrec operands.
407 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
408 if (!AR->getStart()->isZero() && AR->isAffine()) {
409 DoInitialMatch(AR->getStart(), L, Good, Bad, SE);
410 DoInitialMatch(SE.getAddRecExpr(SE.getConstant(AR->getType(), 0),
411 AR->getStepRecurrence(SE),
412 // FIXME: AR->getNoWrapFlags()
413 AR->getLoop(), SCEV::FlagAnyWrap),
414 L, Good, Bad, SE);
415 return;
416 }
417
418 // Handle a multiplication by -1 (negation) if it didn't fold.
419 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S))
420 if (Mul->getOperand(0)->isAllOnesValue()) {
421 SmallVector<const SCEV *, 4> Ops(Mul->op_begin()+1, Mul->op_end());
422 const SCEV *NewMul = SE.getMulExpr(Ops);
423
424 SmallVector<const SCEV *, 4> MyGood;
425 SmallVector<const SCEV *, 4> MyBad;
426 DoInitialMatch(NewMul, L, MyGood, MyBad, SE);
427 const SCEV *NegOne = SE.getSCEV(ConstantInt::getAllOnesValue(
428 SE.getEffectiveSCEVType(NewMul->getType())));
429 for (const SCEV *S : MyGood)
430 Good.push_back(SE.getMulExpr(NegOne, S));
431 for (const SCEV *S : MyBad)
432 Bad.push_back(SE.getMulExpr(NegOne, S));
433 return;
434 }
435
436 // Ok, we can't do anything interesting. Just stuff the whole thing into a
437 // register and hope for the best.
438 Bad.push_back(S);
439}
440
441/// Incorporate loop-variant parts of S into this Formula, attempting to keep
442/// all loop-invariant and loop-computable values in a single base register.
443void Formula::initialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE) {
444 SmallVector<const SCEV *, 4> Good;
445 SmallVector<const SCEV *, 4> Bad;
446 DoInitialMatch(S, L, Good, Bad, SE);
447 if (!Good.empty()) {
448 const SCEV *Sum = SE.getAddExpr(Good);
449 if (!Sum->isZero())
450 BaseRegs.push_back(Sum);
451 HasBaseReg = true;
452 }
453 if (!Bad.empty()) {
454 const SCEV *Sum = SE.getAddExpr(Bad);
455 if (!Sum->isZero())
456 BaseRegs.push_back(Sum);
457 HasBaseReg = true;
458 }
459 canonicalize(*L);
460}
461
462/// Check whether or not this formula satisfies the canonical
463/// representation.
464/// \see Formula::BaseRegs.
465bool Formula::isCanonical(const Loop &L) const {
466 if (!ScaledReg)
467 return BaseRegs.size() <= 1;
468
469 if (Scale != 1)
470 return true;
471
472 if (Scale == 1 && BaseRegs.empty())
473 return false;
474
475 const SCEVAddRecExpr *SAR = dyn_cast<const SCEVAddRecExpr>(ScaledReg);
476 if (SAR && SAR->getLoop() == &L)
477 return true;
478
479 // If ScaledReg is not a recurrent expr, or it is but its loop is not current
480 // loop, meanwhile BaseRegs contains a recurrent expr reg related with current
481 // loop, we want to swap the reg in BaseRegs with ScaledReg.
482 auto I =
483 find_if(make_range(BaseRegs.begin(), BaseRegs.end()), [&](const SCEV *S) {
484 return isa<const SCEVAddRecExpr>(S) &&
485 (cast<SCEVAddRecExpr>(S)->getLoop() == &L);
486 });
487 return I == BaseRegs.end();
488}
489
490/// Helper method to morph a formula into its canonical representation.
491/// \see Formula::BaseRegs.
492/// Every formula having more than one base register, must use the ScaledReg
493/// field. Otherwise, we would have to do special cases everywhere in LSR
494/// to treat reg1 + reg2 + ... the same way as reg1 + 1*reg2 + ...
495/// On the other hand, 1*reg should be canonicalized into reg.
496void Formula::canonicalize(const Loop &L) {
497 if (isCanonical(L))
498 return;
499 // So far we did not need this case. This is easy to implement but it is
500 // useless to maintain dead code. Beside it could hurt compile time.
501 assert(!BaseRegs.empty() && "1*reg => reg, should not be needed.")((!BaseRegs.empty() && "1*reg => reg, should not be needed."
) ? static_cast<void> (0) : __assert_fail ("!BaseRegs.empty() && \"1*reg => reg, should not be needed.\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 501, __PRETTY_FUNCTION__))
;
502
503 // Keep the invariant sum in BaseRegs and one of the variant sum in ScaledReg.
504 if (!ScaledReg) {
505 ScaledReg = BaseRegs.back();
506 BaseRegs.pop_back();
507 Scale = 1;
508 }
509
510 // If ScaledReg is an invariant with respect to L, find the reg from
511 // BaseRegs containing the recurrent expr related with Loop L. Swap the
512 // reg with ScaledReg.
513 const SCEVAddRecExpr *SAR = dyn_cast<const SCEVAddRecExpr>(ScaledReg);
514 if (!SAR || SAR->getLoop() != &L) {
515 auto I = find_if(make_range(BaseRegs.begin(), BaseRegs.end()),
516 [&](const SCEV *S) {
517 return isa<const SCEVAddRecExpr>(S) &&
518 (cast<SCEVAddRecExpr>(S)->getLoop() == &L);
519 });
520 if (I != BaseRegs.end())
521 std::swap(ScaledReg, *I);
522 }
523}
524
525/// Get rid of the scale in the formula.
526/// In other words, this method morphes reg1 + 1*reg2 into reg1 + reg2.
527/// \return true if it was possible to get rid of the scale, false otherwise.
528/// \note After this operation the formula may not be in the canonical form.
529bool Formula::unscale() {
530 if (Scale != 1)
531 return false;
532 Scale = 0;
533 BaseRegs.push_back(ScaledReg);
534 ScaledReg = nullptr;
535 return true;
536}
537
538bool Formula::hasZeroEnd() const {
539 if (UnfoldedOffset || BaseOffset)
540 return false;
541 if (BaseRegs.size() != 1 || ScaledReg)
542 return false;
543 return true;
544}
545
546/// Return the total number of register operands used by this formula. This does
547/// not include register uses implied by non-constant addrec strides.
548size_t Formula::getNumRegs() const {
549 return !!ScaledReg + BaseRegs.size();
550}
551
552/// Return the type of this formula, if it has one, or null otherwise. This type
553/// is meaningless except for the bit size.
554Type *Formula::getType() const {
555 return !BaseRegs.empty() ? BaseRegs.front()->getType() :
556 ScaledReg ? ScaledReg->getType() :
557 BaseGV ? BaseGV->getType() :
558 nullptr;
559}
560
561/// Delete the given base reg from the BaseRegs list.
562void Formula::deleteBaseReg(const SCEV *&S) {
563 if (&S != &BaseRegs.back())
564 std::swap(S, BaseRegs.back());
565 BaseRegs.pop_back();
566}
567
568/// Test if this formula references the given register.
569bool Formula::referencesReg(const SCEV *S) const {
570 return S == ScaledReg || is_contained(BaseRegs, S);
571}
572
573/// Test whether this formula uses registers which are used by uses other than
574/// the use with the given index.
575bool Formula::hasRegsUsedByUsesOtherThan(size_t LUIdx,
576 const RegUseTracker &RegUses) const {
577 if (ScaledReg)
578 if (RegUses.isRegUsedByUsesOtherThan(ScaledReg, LUIdx))
579 return true;
580 for (const SCEV *BaseReg : BaseRegs)
581 if (RegUses.isRegUsedByUsesOtherThan(BaseReg, LUIdx))
582 return true;
583 return false;
584}
585
586#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
587void Formula::print(raw_ostream &OS) const {
588 bool First = true;
589 if (BaseGV) {
590 if (!First) OS << " + "; else First = false;
591 BaseGV->printAsOperand(OS, /*PrintType=*/false);
592 }
593 if (BaseOffset != 0) {
594 if (!First) OS << " + "; else First = false;
595 OS << BaseOffset;
596 }
597 for (const SCEV *BaseReg : BaseRegs) {
598 if (!First) OS << " + "; else First = false;
599 OS << "reg(" << *BaseReg << ')';
600 }
601 if (HasBaseReg && BaseRegs.empty()) {
602 if (!First) OS << " + "; else First = false;
603 OS << "**error: HasBaseReg**";
604 } else if (!HasBaseReg && !BaseRegs.empty()) {
605 if (!First) OS << " + "; else First = false;
606 OS << "**error: !HasBaseReg**";
607 }
608 if (Scale != 0) {
609 if (!First) OS << " + "; else First = false;
610 OS << Scale << "*reg(";
611 if (ScaledReg)
612 OS << *ScaledReg;
613 else
614 OS << "<unknown>";
615 OS << ')';
616 }
617 if (UnfoldedOffset != 0) {
618 if (!First) OS << " + ";
619 OS << "imm(" << UnfoldedOffset << ')';
620 }
621}
622
623LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void Formula::dump() const {
624 print(errs()); errs() << '\n';
625}
626#endif
627
628/// Return true if the given addrec can be sign-extended without changing its
629/// value.
630static bool isAddRecSExtable(const SCEVAddRecExpr *AR, ScalarEvolution &SE) {
631 Type *WideTy =
632 IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(AR->getType()) + 1);
633 return isa<SCEVAddRecExpr>(SE.getSignExtendExpr(AR, WideTy));
634}
635
636/// Return true if the given add can be sign-extended without changing its
637/// value.
638static bool isAddSExtable(const SCEVAddExpr *A, ScalarEvolution &SE) {
639 Type *WideTy =
640 IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(A->getType()) + 1);
641 return isa<SCEVAddExpr>(SE.getSignExtendExpr(A, WideTy));
642}
643
644/// Return true if the given mul can be sign-extended without changing its
645/// value.
646static bool isMulSExtable(const SCEVMulExpr *M, ScalarEvolution &SE) {
647 Type *WideTy =
648 IntegerType::get(SE.getContext(),
649 SE.getTypeSizeInBits(M->getType()) * M->getNumOperands());
650 return isa<SCEVMulExpr>(SE.getSignExtendExpr(M, WideTy));
651}
652
653/// Return an expression for LHS /s RHS, if it can be determined and if the
654/// remainder is known to be zero, or null otherwise. If IgnoreSignificantBits
655/// is true, expressions like (X * Y) /s Y are simplified to Y, ignoring that
656/// the multiplication may overflow, which is useful when the result will be
657/// used in a context where the most significant bits are ignored.
658static const SCEV *getExactSDiv(const SCEV *LHS, const SCEV *RHS,
659 ScalarEvolution &SE,
660 bool IgnoreSignificantBits = false) {
661 // Handle the trivial case, which works for any SCEV type.
662 if (LHS == RHS)
663 return SE.getConstant(LHS->getType(), 1);
664
665 // Handle a few RHS special cases.
666 const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS);
667 if (RC) {
668 const APInt &RA = RC->getAPInt();
669 // Handle x /s -1 as x * -1, to give ScalarEvolution a chance to do
670 // some folding.
671 if (RA.isAllOnesValue())
672 return SE.getMulExpr(LHS, RC);
673 // Handle x /s 1 as x.
674 if (RA == 1)
675 return LHS;
676 }
677
678 // Check for a division of a constant by a constant.
679 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(LHS)) {
680 if (!RC)
681 return nullptr;
682 const APInt &LA = C->getAPInt();
683 const APInt &RA = RC->getAPInt();
684 if (LA.srem(RA) != 0)
685 return nullptr;
686 return SE.getConstant(LA.sdiv(RA));
687 }
688
689 // Distribute the sdiv over addrec operands, if the addrec doesn't overflow.
690 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) {
691 if ((IgnoreSignificantBits || isAddRecSExtable(AR, SE)) && AR->isAffine()) {
692 const SCEV *Step = getExactSDiv(AR->getStepRecurrence(SE), RHS, SE,
693 IgnoreSignificantBits);
694 if (!Step) return nullptr;
695 const SCEV *Start = getExactSDiv(AR->getStart(), RHS, SE,
696 IgnoreSignificantBits);
697 if (!Start) return nullptr;
698 // FlagNW is independent of the start value, step direction, and is
699 // preserved with smaller magnitude steps.
700 // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
701 return SE.getAddRecExpr(Start, Step, AR->getLoop(), SCEV::FlagAnyWrap);
702 }
703 return nullptr;
704 }
705
706 // Distribute the sdiv over add operands, if the add doesn't overflow.
707 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(LHS)) {
708 if (IgnoreSignificantBits || isAddSExtable(Add, SE)) {
709 SmallVector<const SCEV *, 8> Ops;
710 for (const SCEV *S : Add->operands()) {
711 const SCEV *Op = getExactSDiv(S, RHS, SE, IgnoreSignificantBits);
712 if (!Op) return nullptr;
713 Ops.push_back(Op);
714 }
715 return SE.getAddExpr(Ops);
716 }
717 return nullptr;
718 }
719
720 // Check for a multiply operand that we can pull RHS out of.
721 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS)) {
722 if (IgnoreSignificantBits || isMulSExtable(Mul, SE)) {
723 SmallVector<const SCEV *, 4> Ops;
724 bool Found = false;
725 for (const SCEV *S : Mul->operands()) {
726 if (!Found)
727 if (const SCEV *Q = getExactSDiv(S, RHS, SE,
728 IgnoreSignificantBits)) {
729 S = Q;
730 Found = true;
731 }
732 Ops.push_back(S);
733 }
734 return Found ? SE.getMulExpr(Ops) : nullptr;
735 }
736 return nullptr;
737 }
738
739 // Otherwise we don't know.
740 return nullptr;
741}
742
743/// If S involves the addition of a constant integer value, return that integer
744/// value, and mutate S to point to a new SCEV with that value excluded.
745static int64_t ExtractImmediate(const SCEV *&S, ScalarEvolution &SE) {
746 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
747 if (C->getAPInt().getMinSignedBits() <= 64) {
748 S = SE.getConstant(C->getType(), 0);
749 return C->getValue()->getSExtValue();
750 }
751 } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
752 SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());
753 int64_t Result = ExtractImmediate(NewOps.front(), SE);
754 if (Result != 0)
755 S = SE.getAddExpr(NewOps);
756 return Result;
757 } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
758 SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
759 int64_t Result = ExtractImmediate(NewOps.front(), SE);
760 if (Result != 0)
761 S = SE.getAddRecExpr(NewOps, AR->getLoop(),
762 // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
763 SCEV::FlagAnyWrap);
764 return Result;
765 }
766 return 0;
767}
768
769/// If S involves the addition of a GlobalValue address, return that symbol, and
770/// mutate S to point to a new SCEV with that value excluded.
771static GlobalValue *ExtractSymbol(const SCEV *&S, ScalarEvolution &SE) {
772 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
773 if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue())) {
774 S = SE.getConstant(GV->getType(), 0);
775 return GV;
776 }
777 } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
778 SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());
779 GlobalValue *Result = ExtractSymbol(NewOps.back(), SE);
780 if (Result)
781 S = SE.getAddExpr(NewOps);
782 return Result;
783 } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
784 SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
785 GlobalValue *Result = ExtractSymbol(NewOps.front(), SE);
786 if (Result)
787 S = SE.getAddRecExpr(NewOps, AR->getLoop(),
788 // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
789 SCEV::FlagAnyWrap);
790 return Result;
791 }
792 return nullptr;
793}
794
795/// Returns true if the specified instruction is using the specified value as an
796/// address.
797static bool isAddressUse(const TargetTransformInfo &TTI,
798 Instruction *Inst, Value *OperandVal) {
799 bool isAddress = isa<LoadInst>(Inst);
800 if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
801 if (SI->getPointerOperand() == OperandVal)
802 isAddress = true;
803 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
804 // Addressing modes can also be folded into prefetches and a variety
805 // of intrinsics.
806 switch (II->getIntrinsicID()) {
807 case Intrinsic::memset:
808 case Intrinsic::prefetch:
809 if (II->getArgOperand(0) == OperandVal)
810 isAddress = true;
811 break;
812 case Intrinsic::memmove:
813 case Intrinsic::memcpy:
814 if (II->getArgOperand(0) == OperandVal ||
815 II->getArgOperand(1) == OperandVal)
816 isAddress = true;
817 break;
818 default: {
819 MemIntrinsicInfo IntrInfo;
820 if (TTI.getTgtMemIntrinsic(II, IntrInfo)) {
821 if (IntrInfo.PtrVal == OperandVal)
822 isAddress = true;
823 }
824 }
825 }
826 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(Inst)) {
827 if (RMW->getPointerOperand() == OperandVal)
828 isAddress = true;
829 } else if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(Inst)) {
830 if (CmpX->getPointerOperand() == OperandVal)
831 isAddress = true;
832 }
833 return isAddress;
834}
835
836/// Return the type of the memory being accessed.
837static MemAccessTy getAccessType(const TargetTransformInfo &TTI,
838 Instruction *Inst, Value *OperandVal) {
839 MemAccessTy AccessTy(Inst->getType(), MemAccessTy::UnknownAddressSpace);
840 if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
841 AccessTy.MemTy = SI->getOperand(0)->getType();
842 AccessTy.AddrSpace = SI->getPointerAddressSpace();
843 } else if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
844 AccessTy.AddrSpace = LI->getPointerAddressSpace();
845 } else if (const AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(Inst)) {
846 AccessTy.AddrSpace = RMW->getPointerAddressSpace();
847 } else if (const AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(Inst)) {
848 AccessTy.AddrSpace = CmpX->getPointerAddressSpace();
849 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
850 switch (II->getIntrinsicID()) {
851 case Intrinsic::prefetch:
852 case Intrinsic::memset:
853 AccessTy.AddrSpace = II->getArgOperand(0)->getType()->getPointerAddressSpace();
854 AccessTy.MemTy = OperandVal->getType();
855 break;
856 case Intrinsic::memmove:
857 case Intrinsic::memcpy:
858 AccessTy.AddrSpace = OperandVal->getType()->getPointerAddressSpace();
859 AccessTy.MemTy = OperandVal->getType();
860 break;
861 default: {
862 MemIntrinsicInfo IntrInfo;
863 if (TTI.getTgtMemIntrinsic(II, IntrInfo) && IntrInfo.PtrVal) {
864 AccessTy.AddrSpace
865 = IntrInfo.PtrVal->getType()->getPointerAddressSpace();
866 }
867
868 break;
869 }
870 }
871 }
872
873 // All pointers have the same requirements, so canonicalize them to an
874 // arbitrary pointer type to minimize variation.
875 if (PointerType *PTy = dyn_cast<PointerType>(AccessTy.MemTy))
876 AccessTy.MemTy = PointerType::get(IntegerType::get(PTy->getContext(), 1),
877 PTy->getAddressSpace());
878
879 return AccessTy;
880}
881
882/// Return true if this AddRec is already a phi in its loop.
883static bool isExistingPhi(const SCEVAddRecExpr *AR, ScalarEvolution &SE) {
884 for (PHINode &PN : AR->getLoop()->getHeader()->phis()) {
885 if (SE.isSCEVable(PN.getType()) &&
886 (SE.getEffectiveSCEVType(PN.getType()) ==
887 SE.getEffectiveSCEVType(AR->getType())) &&
888 SE.getSCEV(&PN) == AR)
889 return true;
890 }
891 return false;
892}
893
894/// Check if expanding this expression is likely to incur significant cost. This
895/// is tricky because SCEV doesn't track which expressions are actually computed
896/// by the current IR.
897///
898/// We currently allow expansion of IV increments that involve adds,
899/// multiplication by constants, and AddRecs from existing phis.
900///
901/// TODO: Allow UDivExpr if we can find an existing IV increment that is an
902/// obvious multiple of the UDivExpr.
903static bool isHighCostExpansion(const SCEV *S,
904 SmallPtrSetImpl<const SCEV*> &Processed,
905 ScalarEvolution &SE) {
906 // Zero/One operand expressions
907 switch (S->getSCEVType()) {
908 case scUnknown:
909 case scConstant:
910 return false;
911 case scTruncate:
912 return isHighCostExpansion(cast<SCEVTruncateExpr>(S)->getOperand(),
913 Processed, SE);
914 case scZeroExtend:
915 return isHighCostExpansion(cast<SCEVZeroExtendExpr>(S)->getOperand(),
916 Processed, SE);
917 case scSignExtend:
918 return isHighCostExpansion(cast<SCEVSignExtendExpr>(S)->getOperand(),
919 Processed, SE);
920 }
921
922 if (!Processed.insert(S).second)
923 return false;
924
925 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
926 for (const SCEV *S : Add->operands()) {
927 if (isHighCostExpansion(S, Processed, SE))
928 return true;
929 }
930 return false;
931 }
932
933 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
934 if (Mul->getNumOperands() == 2) {
935 // Multiplication by a constant is ok
936 if (isa<SCEVConstant>(Mul->getOperand(0)))
937 return isHighCostExpansion(Mul->getOperand(1), Processed, SE);
938
939 // If we have the value of one operand, check if an existing
940 // multiplication already generates this expression.
941 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Mul->getOperand(1))) {
942 Value *UVal = U->getValue();
943 for (User *UR : UVal->users()) {
944 // If U is a constant, it may be used by a ConstantExpr.
945 Instruction *UI = dyn_cast<Instruction>(UR);
946 if (UI && UI->getOpcode() == Instruction::Mul &&
947 SE.isSCEVable(UI->getType())) {
948 return SE.getSCEV(UI) == Mul;
949 }
950 }
951 }
952 }
953 }
954
955 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
956 if (isExistingPhi(AR, SE))
957 return false;
958 }
959
960 // Fow now, consider any other type of expression (div/mul/min/max) high cost.
961 return true;
962}
963
964/// If any of the instructions in the specified set are trivially dead, delete
965/// them and see if this makes any of their operands subsequently dead.
966static bool
967DeleteTriviallyDeadInstructions(SmallVectorImpl<WeakTrackingVH> &DeadInsts) {
968 bool Changed = false;
969
970 while (!DeadInsts.empty()) {
971 Value *V = DeadInsts.pop_back_val();
972 Instruction *I = dyn_cast_or_null<Instruction>(V);
973
974 if (!I || !isInstructionTriviallyDead(I))
975 continue;
976
977 for (Use &O : I->operands())
978 if (Instruction *U = dyn_cast<Instruction>(O)) {
979 O = nullptr;
980 if (U->use_empty())
981 DeadInsts.emplace_back(U);
982 }
983
984 I->eraseFromParent();
985 Changed = true;
986 }
987
988 return Changed;
989}
990
991namespace {
992
993class LSRUse;
994
995} // end anonymous namespace
996
997/// Check if the addressing mode defined by \p F is completely
998/// folded in \p LU at isel time.
999/// This includes address-mode folding and special icmp tricks.
1000/// This function returns true if \p LU can accommodate what \p F
1001/// defines and up to 1 base + 1 scaled + offset.
1002/// In other words, if \p F has several base registers, this function may
1003/// still return true. Therefore, users still need to account for
1004/// additional base registers and/or unfolded offsets to derive an
1005/// accurate cost model.
1006static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1007 const LSRUse &LU, const Formula &F);
1008
1009// Get the cost of the scaling factor used in F for LU.
1010static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,
1011 const LSRUse &LU, const Formula &F,
1012 const Loop &L);
1013
1014namespace {
1015
1016/// This class is used to measure and compare candidate formulae.
1017class Cost {
1018 const Loop *L = nullptr;
1019 ScalarEvolution *SE = nullptr;
1020 const TargetTransformInfo *TTI = nullptr;
1021 TargetTransformInfo::LSRCost C;
1022
1023public:
1024 Cost() = delete;
1025 Cost(const Loop *L, ScalarEvolution &SE, const TargetTransformInfo &TTI) :
1026 L(L), SE(&SE), TTI(&TTI) {
1027 C.Insns = 0;
1028 C.NumRegs = 0;
1029 C.AddRecCost = 0;
1030 C.NumIVMuls = 0;
1031 C.NumBaseAdds = 0;
1032 C.ImmCost = 0;
1033 C.SetupCost = 0;
1034 C.ScaleCost = 0;
1035 }
1036
1037 bool isLess(Cost &Other);
1038
1039 void Lose();
1040
1041#ifndef NDEBUG
1042 // Once any of the metrics loses, they must all remain losers.
1043 bool isValid() {
1044 return ((C.Insns | C.NumRegs | C.AddRecCost | C.NumIVMuls | C.NumBaseAdds
1045 | C.ImmCost | C.SetupCost | C.ScaleCost) != ~0u)
1046 || ((C.Insns & C.NumRegs & C.AddRecCost & C.NumIVMuls & C.NumBaseAdds
1047 & C.ImmCost & C.SetupCost & C.ScaleCost) == ~0u);
1048 }
1049#endif
1050
1051 bool isLoser() {
1052 assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void>
(0) : __assert_fail ("isValid() && \"invalid cost\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1052, __PRETTY_FUNCTION__))
;
1053 return C.NumRegs == ~0u;
1054 }
1055
1056 void RateFormula(const Formula &F,
1057 SmallPtrSetImpl<const SCEV *> &Regs,
1058 const DenseSet<const SCEV *> &VisitedRegs,
1059 const LSRUse &LU,
1060 SmallPtrSetImpl<const SCEV *> *LoserRegs = nullptr);
1061
1062 void print(raw_ostream &OS) const;
1063 void dump() const;
1064
1065private:
1066 void RateRegister(const Formula &F, const SCEV *Reg,
1067 SmallPtrSetImpl<const SCEV *> &Regs);
1068 void RatePrimaryRegister(const Formula &F, const SCEV *Reg,
1069 SmallPtrSetImpl<const SCEV *> &Regs,
1070 SmallPtrSetImpl<const SCEV *> *LoserRegs);
1071};
1072
1073/// An operand value in an instruction which is to be replaced with some
1074/// equivalent, possibly strength-reduced, replacement.
1075struct LSRFixup {
1076 /// The instruction which will be updated.
1077 Instruction *UserInst = nullptr;
1078
1079 /// The operand of the instruction which will be replaced. The operand may be
1080 /// used more than once; every instance will be replaced.
1081 Value *OperandValToReplace = nullptr;
1082
1083 /// If this user is to use the post-incremented value of an induction
1084 /// variable, this set is non-empty and holds the loops associated with the
1085 /// induction variable.
1086 PostIncLoopSet PostIncLoops;
1087
1088 /// A constant offset to be added to the LSRUse expression. This allows
1089 /// multiple fixups to share the same LSRUse with different offsets, for
1090 /// example in an unrolled loop.
1091 int64_t Offset = 0;
1092
1093 LSRFixup() = default;
1094
1095 bool isUseFullyOutsideLoop(const Loop *L) const;
1096
1097 void print(raw_ostream &OS) const;
1098 void dump() const;
1099};
1100
1101/// A DenseMapInfo implementation for holding DenseMaps and DenseSets of sorted
1102/// SmallVectors of const SCEV*.
1103struct UniquifierDenseMapInfo {
1104 static SmallVector<const SCEV *, 4> getEmptyKey() {
1105 SmallVector<const SCEV *, 4> V;
1106 V.push_back(reinterpret_cast<const SCEV *>(-1));
1107 return V;
1108 }
1109
1110 static SmallVector<const SCEV *, 4> getTombstoneKey() {
1111 SmallVector<const SCEV *, 4> V;
1112 V.push_back(reinterpret_cast<const SCEV *>(-2));
1113 return V;
1114 }
1115
1116 static unsigned getHashValue(const SmallVector<const SCEV *, 4> &V) {
1117 return static_cast<unsigned>(hash_combine_range(V.begin(), V.end()));
1118 }
1119
1120 static bool isEqual(const SmallVector<const SCEV *, 4> &LHS,
1121 const SmallVector<const SCEV *, 4> &RHS) {
1122 return LHS == RHS;
1123 }
1124};
1125
1126/// This class holds the state that LSR keeps for each use in IVUsers, as well
1127/// as uses invented by LSR itself. It includes information about what kinds of
1128/// things can be folded into the user, information about the user itself, and
1129/// information about how the use may be satisfied. TODO: Represent multiple
1130/// users of the same expression in common?
1131class LSRUse {
1132 DenseSet<SmallVector<const SCEV *, 4>, UniquifierDenseMapInfo> Uniquifier;
1133
1134public:
1135 /// An enum for a kind of use, indicating what types of scaled and immediate
1136 /// operands it might support.
1137 enum KindType {
1138 Basic, ///< A normal use, with no folding.
1139 Special, ///< A special case of basic, allowing -1 scales.
1140 Address, ///< An address use; folding according to TargetLowering
1141 ICmpZero ///< An equality icmp with both operands folded into one.
1142 // TODO: Add a generic icmp too?
1143 };
1144
1145 using SCEVUseKindPair = PointerIntPair<const SCEV *, 2, KindType>;
1146
1147 KindType Kind;
1148 MemAccessTy AccessTy;
1149
1150 /// The list of operands which are to be replaced.
1151 SmallVector<LSRFixup, 8> Fixups;
1152
1153 /// Keep track of the min and max offsets of the fixups.
1154 int64_t MinOffset = std::numeric_limits<int64_t>::max();
1155 int64_t MaxOffset = std::numeric_limits<int64_t>::min();
1156
1157 /// This records whether all of the fixups using this LSRUse are outside of
1158 /// the loop, in which case some special-case heuristics may be used.
1159 bool AllFixupsOutsideLoop = true;
1160
1161 /// RigidFormula is set to true to guarantee that this use will be associated
1162 /// with a single formula--the one that initially matched. Some SCEV
1163 /// expressions cannot be expanded. This allows LSR to consider the registers
1164 /// used by those expressions without the need to expand them later after
1165 /// changing the formula.
1166 bool RigidFormula = false;
1167
1168 /// This records the widest use type for any fixup using this
1169 /// LSRUse. FindUseWithSimilarFormula can't consider uses with different max
1170 /// fixup widths to be equivalent, because the narrower one may be relying on
1171 /// the implicit truncation to truncate away bogus bits.
1172 Type *WidestFixupType = nullptr;
1173
1174 /// A list of ways to build a value that can satisfy this user. After the
1175 /// list is populated, one of these is selected heuristically and used to
1176 /// formulate a replacement for OperandValToReplace in UserInst.
1177 SmallVector<Formula, 12> Formulae;
1178
1179 /// The set of register candidates used by all formulae in this LSRUse.
1180 SmallPtrSet<const SCEV *, 4> Regs;
1181
1182 LSRUse(KindType K, MemAccessTy AT) : Kind(K), AccessTy(AT) {}
1183
1184 LSRFixup &getNewFixup() {
1185 Fixups.push_back(LSRFixup());
1186 return Fixups.back();
1187 }
1188
1189 void pushFixup(LSRFixup &f) {
1190 Fixups.push_back(f);
1191 if (f.Offset > MaxOffset)
1192 MaxOffset = f.Offset;
1193 if (f.Offset < MinOffset)
1194 MinOffset = f.Offset;
1195 }
1196
1197 bool HasFormulaWithSameRegs(const Formula &F) const;
1198 float getNotSelectedProbability(const SCEV *Reg) const;
1199 bool InsertFormula(const Formula &F, const Loop &L);
1200 void DeleteFormula(Formula &F);
1201 void RecomputeRegs(size_t LUIdx, RegUseTracker &Reguses);
1202
1203 void print(raw_ostream &OS) const;
1204 void dump() const;
1205};
1206
1207} // end anonymous namespace
1208
1209static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1210 LSRUse::KindType Kind, MemAccessTy AccessTy,
1211 GlobalValue *BaseGV, int64_t BaseOffset,
1212 bool HasBaseReg, int64_t Scale,
1213 Instruction *Fixup = nullptr);
1214
1215static unsigned getSetupCost(const SCEV *Reg, unsigned Depth) {
1216 if (isa<SCEVUnknown>(Reg) || isa<SCEVConstant>(Reg))
1217 return 1;
1218 if (Depth == 0)
1219 return 0;
1220 if (const auto *S = dyn_cast<SCEVAddRecExpr>(Reg))
1221 return getSetupCost(S->getStart(), Depth - 1);
1222 if (auto S = dyn_cast<SCEVCastExpr>(Reg))
1223 return getSetupCost(S->getOperand(), Depth - 1);
1224 if (auto S = dyn_cast<SCEVNAryExpr>(Reg))
1225 return std::accumulate(S->op_begin(), S->op_end(), 0,
1226 [&](unsigned i, const SCEV *Reg) {
1227 return i + getSetupCost(Reg, Depth - 1);
1228 });
1229 if (auto S = dyn_cast<SCEVUDivExpr>(Reg))
1230 return getSetupCost(S->getLHS(), Depth - 1) +
1231 getSetupCost(S->getRHS(), Depth - 1);
1232 return 0;
1233}
1234
1235/// Tally up interesting quantities from the given register.
1236void Cost::RateRegister(const Formula &F, const SCEV *Reg,
1237 SmallPtrSetImpl<const SCEV *> &Regs) {
1238 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Reg)) {
1239 // If this is an addrec for another loop, it should be an invariant
1240 // with respect to L since L is the innermost loop (at least
1241 // for now LSR only handles innermost loops).
1242 if (AR->getLoop() != L) {
1243 // If the AddRec exists, consider it's register free and leave it alone.
1244 if (isExistingPhi(AR, *SE))
1245 return;
1246
1247 // It is bad to allow LSR for current loop to add induction variables
1248 // for its sibling loops.
1249 if (!AR->getLoop()->contains(L)) {
1250 Lose();
1251 return;
1252 }
1253
1254 // Otherwise, it will be an invariant with respect to Loop L.
1255 ++C.NumRegs;
1256 return;
1257 }
1258
1259 unsigned LoopCost = 1;
1260 if (TTI->isIndexedLoadLegal(TTI->MIM_PostInc, AR->getType()) ||
1261 TTI->isIndexedStoreLegal(TTI->MIM_PostInc, AR->getType())) {
1262
1263 // If the step size matches the base offset, we could use pre-indexed
1264 // addressing.
1265 if (TTI->shouldFavorBackedgeIndex(L)) {
1266 if (auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(*SE)))
1267 if (Step->getAPInt() == F.BaseOffset)
1268 LoopCost = 0;
1269 }
1270
1271 if (TTI->shouldFavorPostInc()) {
1272 const SCEV *LoopStep = AR->getStepRecurrence(*SE);
1273 if (isa<SCEVConstant>(LoopStep)) {
1274 const SCEV *LoopStart = AR->getStart();
1275 if (!isa<SCEVConstant>(LoopStart) &&
1276 SE->isLoopInvariant(LoopStart, L))
1277 LoopCost = 0;
1278 }
1279 }
1280 }
1281 C.AddRecCost += LoopCost;
1282
1283 // Add the step value register, if it needs one.
1284 // TODO: The non-affine case isn't precisely modeled here.
1285 if (!AR->isAffine() || !isa<SCEVConstant>(AR->getOperand(1))) {
1286 if (!Regs.count(AR->getOperand(1))) {
1287 RateRegister(F, AR->getOperand(1), Regs);
1288 if (isLoser())
1289 return;
1290 }
1291 }
1292 }
1293 ++C.NumRegs;
1294
1295 // Rough heuristic; favor registers which don't require extra setup
1296 // instructions in the preheader.
1297 C.SetupCost += getSetupCost(Reg, SetupCostDepthLimit);
1298 // Ensure we don't, even with the recusion limit, produce invalid costs.
1299 C.SetupCost = std::min<unsigned>(C.SetupCost, 1 << 16);
1300
1301 C.NumIVMuls += isa<SCEVMulExpr>(Reg) &&
1302 SE->hasComputableLoopEvolution(Reg, L);
1303}
1304
1305/// Record this register in the set. If we haven't seen it before, rate
1306/// it. Optional LoserRegs provides a way to declare any formula that refers to
1307/// one of those regs an instant loser.
1308void Cost::RatePrimaryRegister(const Formula &F, const SCEV *Reg,
1309 SmallPtrSetImpl<const SCEV *> &Regs,
1310 SmallPtrSetImpl<const SCEV *> *LoserRegs) {
1311 if (LoserRegs && LoserRegs->count(Reg)) {
1312 Lose();
1313 return;
1314 }
1315 if (Regs.insert(Reg).second) {
1316 RateRegister(F, Reg, Regs);
1317 if (LoserRegs && isLoser())
1318 LoserRegs->insert(Reg);
1319 }
1320}
1321
1322void Cost::RateFormula(const Formula &F,
1323 SmallPtrSetImpl<const SCEV *> &Regs,
1324 const DenseSet<const SCEV *> &VisitedRegs,
1325 const LSRUse &LU,
1326 SmallPtrSetImpl<const SCEV *> *LoserRegs) {
1327 assert(F.isCanonical(*L) && "Cost is accurate only for canonical formula")((F.isCanonical(*L) && "Cost is accurate only for canonical formula"
) ? static_cast<void> (0) : __assert_fail ("F.isCanonical(*L) && \"Cost is accurate only for canonical formula\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1327, __PRETTY_FUNCTION__))
;
1328 // Tally up the registers.
1329 unsigned PrevAddRecCost = C.AddRecCost;
1330 unsigned PrevNumRegs = C.NumRegs;
1331 unsigned PrevNumBaseAdds = C.NumBaseAdds;
1332 if (const SCEV *ScaledReg = F.ScaledReg) {
1333 if (VisitedRegs.count(ScaledReg)) {
1334 Lose();
1335 return;
1336 }
1337 RatePrimaryRegister(F, ScaledReg, Regs, LoserRegs);
1338 if (isLoser())
1339 return;
1340 }
1341 for (const SCEV *BaseReg : F.BaseRegs) {
1342 if (VisitedRegs.count(BaseReg)) {
1343 Lose();
1344 return;
1345 }
1346 RatePrimaryRegister(F, BaseReg, Regs, LoserRegs);
1347 if (isLoser())
1348 return;
1349 }
1350
1351 // Determine how many (unfolded) adds we'll need inside the loop.
1352 size_t NumBaseParts = F.getNumRegs();
1353 if (NumBaseParts > 1)
1354 // Do not count the base and a possible second register if the target
1355 // allows to fold 2 registers.
1356 C.NumBaseAdds +=
1357 NumBaseParts - (1 + (F.Scale && isAMCompletelyFolded(*TTI, LU, F)));
1358 C.NumBaseAdds += (F.UnfoldedOffset != 0);
1359
1360 // Accumulate non-free scaling amounts.
1361 C.ScaleCost += getScalingFactorCost(*TTI, LU, F, *L);
1362
1363 // Tally up the non-zero immediates.
1364 for (const LSRFixup &Fixup : LU.Fixups) {
1365 int64_t O = Fixup.Offset;
1366 int64_t Offset = (uint64_t)O + F.BaseOffset;
1367 if (F.BaseGV)
1368 C.ImmCost += 64; // Handle symbolic values conservatively.
1369 // TODO: This should probably be the pointer size.
1370 else if (Offset != 0)
1371 C.ImmCost += APInt(64, Offset, true).getMinSignedBits();
1372
1373 // Check with target if this offset with this instruction is
1374 // specifically not supported.
1375 if (LU.Kind == LSRUse::Address && Offset != 0 &&
1376 !isAMCompletelyFolded(*TTI, LSRUse::Address, LU.AccessTy, F.BaseGV,
1377 Offset, F.HasBaseReg, F.Scale, Fixup.UserInst))
1378 C.NumBaseAdds++;
1379 }
1380
1381 // If we don't count instruction cost exit here.
1382 if (!InsnsCost) {
1383 assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void>
(0) : __assert_fail ("isValid() && \"invalid cost\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1383, __PRETTY_FUNCTION__))
;
1384 return;
1385 }
1386
1387 // Treat every new register that exceeds TTI.getNumberOfRegisters() - 1 as
1388 // additional instruction (at least fill).
1389 // TODO: Need distinguish register class?
1390 unsigned TTIRegNum = TTI->getNumberOfRegisters(
1391 TTI->getRegisterClassForType(false, F.getType())) - 1;
1392 if (C.NumRegs > TTIRegNum) {
1393 // Cost already exceeded TTIRegNum, then only newly added register can add
1394 // new instructions.
1395 if (PrevNumRegs > TTIRegNum)
1396 C.Insns += (C.NumRegs - PrevNumRegs);
1397 else
1398 C.Insns += (C.NumRegs - TTIRegNum);
1399 }
1400
1401 // If ICmpZero formula ends with not 0, it could not be replaced by
1402 // just add or sub. We'll need to compare final result of AddRec.
1403 // That means we'll need an additional instruction. But if the target can
1404 // macro-fuse a compare with a branch, don't count this extra instruction.
1405 // For -10 + {0, +, 1}:
1406 // i = i + 1;
1407 // cmp i, 10
1408 //
1409 // For {-10, +, 1}:
1410 // i = i + 1;
1411 if (LU.Kind == LSRUse::ICmpZero && !F.hasZeroEnd() &&
1412 !TTI->canMacroFuseCmp())
1413 C.Insns++;
1414 // Each new AddRec adds 1 instruction to calculation.
1415 C.Insns += (C.AddRecCost - PrevAddRecCost);
1416
1417 // BaseAdds adds instructions for unfolded registers.
1418 if (LU.Kind != LSRUse::ICmpZero)
1419 C.Insns += C.NumBaseAdds - PrevNumBaseAdds;
1420 assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void>
(0) : __assert_fail ("isValid() && \"invalid cost\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1420, __PRETTY_FUNCTION__))
;
1421}
1422
1423/// Set this cost to a losing value.
1424void Cost::Lose() {
1425 C.Insns = std::numeric_limits<unsigned>::max();
1426 C.NumRegs = std::numeric_limits<unsigned>::max();
1427 C.AddRecCost = std::numeric_limits<unsigned>::max();
1428 C.NumIVMuls = std::numeric_limits<unsigned>::max();
1429 C.NumBaseAdds = std::numeric_limits<unsigned>::max();
1430 C.ImmCost = std::numeric_limits<unsigned>::max();
1431 C.SetupCost = std::numeric_limits<unsigned>::max();
1432 C.ScaleCost = std::numeric_limits<unsigned>::max();
1433}
1434
1435/// Choose the lower cost.
1436bool Cost::isLess(Cost &Other) {
1437 if (InsnsCost.getNumOccurrences() > 0 && InsnsCost &&
1438 C.Insns != Other.C.Insns)
1439 return C.Insns < Other.C.Insns;
1440 return TTI->isLSRCostLess(C, Other.C);
1441}
1442
1443#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1444void Cost::print(raw_ostream &OS) const {
1445 if (InsnsCost)
1446 OS << C.Insns << " instruction" << (C.Insns == 1 ? " " : "s ");
1447 OS << C.NumRegs << " reg" << (C.NumRegs == 1 ? "" : "s");
1448 if (C.AddRecCost != 0)
1449 OS << ", with addrec cost " << C.AddRecCost;
1450 if (C.NumIVMuls != 0)
1451 OS << ", plus " << C.NumIVMuls << " IV mul"
1452 << (C.NumIVMuls == 1 ? "" : "s");
1453 if (C.NumBaseAdds != 0)
1454 OS << ", plus " << C.NumBaseAdds << " base add"
1455 << (C.NumBaseAdds == 1 ? "" : "s");
1456 if (C.ScaleCost != 0)
1457 OS << ", plus " << C.ScaleCost << " scale cost";
1458 if (C.ImmCost != 0)
1459 OS << ", plus " << C.ImmCost << " imm cost";
1460 if (C.SetupCost != 0)
1461 OS << ", plus " << C.SetupCost << " setup cost";
1462}
1463
1464LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void Cost::dump() const {
1465 print(errs()); errs() << '\n';
1466}
1467#endif
1468
1469/// Test whether this fixup always uses its value outside of the given loop.
1470bool LSRFixup::isUseFullyOutsideLoop(const Loop *L) const {
1471 // PHI nodes use their value in their incoming blocks.
1472 if (const PHINode *PN = dyn_cast<PHINode>(UserInst)) {
1473 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
1474 if (PN->getIncomingValue(i) == OperandValToReplace &&
1475 L->contains(PN->getIncomingBlock(i)))
1476 return false;
1477 return true;
1478 }
1479
1480 return !L->contains(UserInst);
1481}
1482
1483#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1484void LSRFixup::print(raw_ostream &OS) const {
1485 OS << "UserInst=";
1486 // Store is common and interesting enough to be worth special-casing.
1487 if (StoreInst *Store = dyn_cast<StoreInst>(UserInst)) {
1488 OS << "store ";
1489 Store->getOperand(0)->printAsOperand(OS, /*PrintType=*/false);
1490 } else if (UserInst->getType()->isVoidTy())
1491 OS << UserInst->getOpcodeName();
1492 else
1493 UserInst->printAsOperand(OS, /*PrintType=*/false);
1494
1495 OS << ", OperandValToReplace=";
1496 OperandValToReplace->printAsOperand(OS, /*PrintType=*/false);
1497
1498 for (const Loop *PIL : PostIncLoops) {
1499 OS << ", PostIncLoop=";
1500 PIL->getHeader()->printAsOperand(OS, /*PrintType=*/false);
1501 }
1502
1503 if (Offset != 0)
1504 OS << ", Offset=" << Offset;
1505}
1506
1507LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void LSRFixup::dump() const {
1508 print(errs()); errs() << '\n';
1509}
1510#endif
1511
1512/// Test whether this use as a formula which has the same registers as the given
1513/// formula.
1514bool LSRUse::HasFormulaWithSameRegs(const Formula &F) const {
1515 SmallVector<const SCEV *, 4> Key = F.BaseRegs;
1516 if (F.ScaledReg) Key.push_back(F.ScaledReg);
1517 // Unstable sort by host order ok, because this is only used for uniquifying.
1518 llvm::sort(Key);
1519 return Uniquifier.count(Key);
1520}
1521
1522/// The function returns a probability of selecting formula without Reg.
1523float LSRUse::getNotSelectedProbability(const SCEV *Reg) const {
1524 unsigned FNum = 0;
1525 for (const Formula &F : Formulae)
1526 if (F.referencesReg(Reg))
1527 FNum++;
1528 return ((float)(Formulae.size() - FNum)) / Formulae.size();
1529}
1530
1531/// If the given formula has not yet been inserted, add it to the list, and
1532/// return true. Return false otherwise. The formula must be in canonical form.
1533bool LSRUse::InsertFormula(const Formula &F, const Loop &L) {
1534 assert(F.isCanonical(L) && "Invalid canonical representation")((F.isCanonical(L) && "Invalid canonical representation"
) ? static_cast<void> (0) : __assert_fail ("F.isCanonical(L) && \"Invalid canonical representation\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1534, __PRETTY_FUNCTION__))
;
1535
1536 if (!Formulae.empty() && RigidFormula)
1537 return false;
1538
1539 SmallVector<const SCEV *, 4> Key = F.BaseRegs;
1540 if (F.ScaledReg) Key.push_back(F.ScaledReg);
1541 // Unstable sort by host order ok, because this is only used for uniquifying.
1542 llvm::sort(Key);
1543
1544 if (!Uniquifier.insert(Key).second)
1545 return false;
1546
1547 // Using a register to hold the value of 0 is not profitable.
1548 assert((!F.ScaledReg || !F.ScaledReg->isZero()) &&(((!F.ScaledReg || !F.ScaledReg->isZero()) && "Zero allocated in a scaled register!"
) ? static_cast<void> (0) : __assert_fail ("(!F.ScaledReg || !F.ScaledReg->isZero()) && \"Zero allocated in a scaled register!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1549, __PRETTY_FUNCTION__))
1549 "Zero allocated in a scaled register!")(((!F.ScaledReg || !F.ScaledReg->isZero()) && "Zero allocated in a scaled register!"
) ? static_cast<void> (0) : __assert_fail ("(!F.ScaledReg || !F.ScaledReg->isZero()) && \"Zero allocated in a scaled register!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1549, __PRETTY_FUNCTION__))
;
1550#ifndef NDEBUG
1551 for (const SCEV *BaseReg : F.BaseRegs)
1552 assert(!BaseReg->isZero() && "Zero allocated in a base register!")((!BaseReg->isZero() && "Zero allocated in a base register!"
) ? static_cast<void> (0) : __assert_fail ("!BaseReg->isZero() && \"Zero allocated in a base register!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1552, __PRETTY_FUNCTION__))
;
1553#endif
1554
1555 // Add the formula to the list.
1556 Formulae.push_back(F);
1557
1558 // Record registers now being used by this use.
1559 Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end());
1560 if (F.ScaledReg)
1561 Regs.insert(F.ScaledReg);
1562
1563 return true;
1564}
1565
1566/// Remove the given formula from this use's list.
1567void LSRUse::DeleteFormula(Formula &F) {
1568 if (&F != &Formulae.back())
1569 std::swap(F, Formulae.back());
1570 Formulae.pop_back();
1571}
1572
1573/// Recompute the Regs field, and update RegUses.
1574void LSRUse::RecomputeRegs(size_t LUIdx, RegUseTracker &RegUses) {
1575 // Now that we've filtered out some formulae, recompute the Regs set.
1576 SmallPtrSet<const SCEV *, 4> OldRegs = std::move(Regs);
1577 Regs.clear();
1578 for (const Formula &F : Formulae) {
1579 if (F.ScaledReg) Regs.insert(F.ScaledReg);
1580 Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end());
1581 }
1582
1583 // Update the RegTracker.
1584 for (const SCEV *S : OldRegs)
1585 if (!Regs.count(S))
1586 RegUses.dropRegister(S, LUIdx);
1587}
1588
1589#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1590void LSRUse::print(raw_ostream &OS) const {
1591 OS << "LSR Use: Kind=";
1592 switch (Kind) {
1593 case Basic: OS << "Basic"; break;
1594 case Special: OS << "Special"; break;
1595 case ICmpZero: OS << "ICmpZero"; break;
1596 case Address:
1597 OS << "Address of ";
1598 if (AccessTy.MemTy->isPointerTy())
1599 OS << "pointer"; // the full pointer type could be really verbose
1600 else {
1601 OS << *AccessTy.MemTy;
1602 }
1603
1604 OS << " in addrspace(" << AccessTy.AddrSpace << ')';
1605 }
1606
1607 OS << ", Offsets={";
1608 bool NeedComma = false;
1609 for (const LSRFixup &Fixup : Fixups) {
1610 if (NeedComma) OS << ',';
1611 OS << Fixup.Offset;
1612 NeedComma = true;
1613 }
1614 OS << '}';
1615
1616 if (AllFixupsOutsideLoop)
1617 OS << ", all-fixups-outside-loop";
1618
1619 if (WidestFixupType)
1620 OS << ", widest fixup type: " << *WidestFixupType;
1621}
1622
1623LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void LSRUse::dump() const {
1624 print(errs()); errs() << '\n';
1625}
1626#endif
1627
1628static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1629 LSRUse::KindType Kind, MemAccessTy AccessTy,
1630 GlobalValue *BaseGV, int64_t BaseOffset,
1631 bool HasBaseReg, int64_t Scale,
1632 Instruction *Fixup/*= nullptr*/) {
1633 switch (Kind) {
1634 case LSRUse::Address:
1635 return TTI.isLegalAddressingMode(AccessTy.MemTy, BaseGV, BaseOffset,
1636 HasBaseReg, Scale, AccessTy.AddrSpace, Fixup);
1637
1638 case LSRUse::ICmpZero:
1639 // There's not even a target hook for querying whether it would be legal to
1640 // fold a GV into an ICmp.
1641 if (BaseGV)
1642 return false;
1643
1644 // ICmp only has two operands; don't allow more than two non-trivial parts.
1645 if (Scale != 0 && HasBaseReg && BaseOffset != 0)
1646 return false;
1647
1648 // ICmp only supports no scale or a -1 scale, as we can "fold" a -1 scale by
1649 // putting the scaled register in the other operand of the icmp.
1650 if (Scale != 0 && Scale != -1)
1651 return false;
1652
1653 // If we have low-level target information, ask the target if it can fold an
1654 // integer immediate on an icmp.
1655 if (BaseOffset != 0) {
1656 // We have one of:
1657 // ICmpZero BaseReg + BaseOffset => ICmp BaseReg, -BaseOffset
1658 // ICmpZero -1*ScaleReg + BaseOffset => ICmp ScaleReg, BaseOffset
1659 // Offs is the ICmp immediate.
1660 if (Scale == 0)
1661 // The cast does the right thing with
1662 // std::numeric_limits<int64_t>::min().
1663 BaseOffset = -(uint64_t)BaseOffset;
1664 return TTI.isLegalICmpImmediate(BaseOffset);
1665 }
1666
1667 // ICmpZero BaseReg + -1*ScaleReg => ICmp BaseReg, ScaleReg
1668 return true;
1669
1670 case LSRUse::Basic:
1671 // Only handle single-register values.
1672 return !BaseGV && Scale == 0 && BaseOffset == 0;
1673
1674 case LSRUse::Special:
1675 // Special case Basic to handle -1 scales.
1676 return !BaseGV && (Scale == 0 || Scale == -1) && BaseOffset == 0;
1677 }
1678
1679 llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1679)
;
1680}
1681
1682static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1683 int64_t MinOffset, int64_t MaxOffset,
1684 LSRUse::KindType Kind, MemAccessTy AccessTy,
1685 GlobalValue *BaseGV, int64_t BaseOffset,
1686 bool HasBaseReg, int64_t Scale) {
1687 // Check for overflow.
1688 if (((int64_t)((uint64_t)BaseOffset + MinOffset) > BaseOffset) !=
1689 (MinOffset > 0))
1690 return false;
1691 MinOffset = (uint64_t)BaseOffset + MinOffset;
1692 if (((int64_t)((uint64_t)BaseOffset + MaxOffset) > BaseOffset) !=
1693 (MaxOffset > 0))
1694 return false;
1695 MaxOffset = (uint64_t)BaseOffset + MaxOffset;
1696
1697 return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MinOffset,
1698 HasBaseReg, Scale) &&
1699 isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MaxOffset,
1700 HasBaseReg, Scale);
1701}
1702
1703static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1704 int64_t MinOffset, int64_t MaxOffset,
1705 LSRUse::KindType Kind, MemAccessTy AccessTy,
1706 const Formula &F, const Loop &L) {
1707 // For the purpose of isAMCompletelyFolded either having a canonical formula
1708 // or a scale not equal to zero is correct.
1709 // Problems may arise from non canonical formulae having a scale == 0.
1710 // Strictly speaking it would best to just rely on canonical formulae.
1711 // However, when we generate the scaled formulae, we first check that the
1712 // scaling factor is profitable before computing the actual ScaledReg for
1713 // compile time sake.
1714 assert((F.isCanonical(L) || F.Scale != 0))(((F.isCanonical(L) || F.Scale != 0)) ? static_cast<void>
(0) : __assert_fail ("(F.isCanonical(L) || F.Scale != 0)", "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1714, __PRETTY_FUNCTION__))
;
1715 return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy,
1716 F.BaseGV, F.BaseOffset, F.HasBaseReg, F.Scale);
1717}
1718
1719/// Test whether we know how to expand the current formula.
1720static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset,
1721 int64_t MaxOffset, LSRUse::KindType Kind,
1722 MemAccessTy AccessTy, GlobalValue *BaseGV,
1723 int64_t BaseOffset, bool HasBaseReg, int64_t Scale) {
1724 // We know how to expand completely foldable formulae.
1725 return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV,
1726 BaseOffset, HasBaseReg, Scale) ||
1727 // Or formulae that use a base register produced by a sum of base
1728 // registers.
1729 (Scale == 1 &&
1730 isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy,
1731 BaseGV, BaseOffset, true, 0));
1732}
1733
1734static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset,
1735 int64_t MaxOffset, LSRUse::KindType Kind,
1736 MemAccessTy AccessTy, const Formula &F) {
1737 return isLegalUse(TTI, MinOffset, MaxOffset, Kind, AccessTy, F.BaseGV,
1738 F.BaseOffset, F.HasBaseReg, F.Scale);
1739}
1740
1741static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1742 const LSRUse &LU, const Formula &F) {
1743 // Target may want to look at the user instructions.
1744 if (LU.Kind == LSRUse::Address && TTI.LSRWithInstrQueries()) {
1745 for (const LSRFixup &Fixup : LU.Fixups)
1746 if (!isAMCompletelyFolded(TTI, LSRUse::Address, LU.AccessTy, F.BaseGV,
1747 (F.BaseOffset + Fixup.Offset), F.HasBaseReg,
1748 F.Scale, Fixup.UserInst))
1749 return false;
1750 return true;
1751 }
1752
1753 return isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind,
1754 LU.AccessTy, F.BaseGV, F.BaseOffset, F.HasBaseReg,
1755 F.Scale);
1756}
1757
1758static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,
1759 const LSRUse &LU, const Formula &F,
1760 const Loop &L) {
1761 if (!F.Scale)
1762 return 0;
1763
1764 // If the use is not completely folded in that instruction, we will have to
1765 // pay an extra cost only for scale != 1.
1766 if (!isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind,
1767 LU.AccessTy, F, L))
1768 return F.Scale != 1;
1769
1770 switch (LU.Kind) {
1771 case LSRUse::Address: {
1772 // Check the scaling factor cost with both the min and max offsets.
1773 int ScaleCostMinOffset = TTI.getScalingFactorCost(
1774 LU.AccessTy.MemTy, F.BaseGV, F.BaseOffset + LU.MinOffset, F.HasBaseReg,
1775 F.Scale, LU.AccessTy.AddrSpace);
1776 int ScaleCostMaxOffset = TTI.getScalingFactorCost(
1777 LU.AccessTy.MemTy, F.BaseGV, F.BaseOffset + LU.MaxOffset, F.HasBaseReg,
1778 F.Scale, LU.AccessTy.AddrSpace);
1779
1780 assert(ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 &&((ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >=
0 && "Legal addressing mode has an illegal cost!") ?
static_cast<void> (0) : __assert_fail ("ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && \"Legal addressing mode has an illegal cost!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1781, __PRETTY_FUNCTION__))
1781 "Legal addressing mode has an illegal cost!")((ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >=
0 && "Legal addressing mode has an illegal cost!") ?
static_cast<void> (0) : __assert_fail ("ScaleCostMinOffset >= 0 && ScaleCostMaxOffset >= 0 && \"Legal addressing mode has an illegal cost!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1781, __PRETTY_FUNCTION__))
;
1782 return std::max(ScaleCostMinOffset, ScaleCostMaxOffset);
1783 }
1784 case LSRUse::ICmpZero:
1785 case LSRUse::Basic:
1786 case LSRUse::Special:
1787 // The use is completely folded, i.e., everything is folded into the
1788 // instruction.
1789 return 0;
1790 }
1791
1792 llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1792)
;
1793}
1794
1795static bool isAlwaysFoldable(const TargetTransformInfo &TTI,
1796 LSRUse::KindType Kind, MemAccessTy AccessTy,
1797 GlobalValue *BaseGV, int64_t BaseOffset,
1798 bool HasBaseReg) {
1799 // Fast-path: zero is always foldable.
1800 if (BaseOffset == 0 && !BaseGV) return true;
1801
1802 // Conservatively, create an address with an immediate and a
1803 // base and a scale.
1804 int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1;
1805
1806 // Canonicalize a scale of 1 to a base register if the formula doesn't
1807 // already have a base register.
1808 if (!HasBaseReg && Scale == 1) {
1809 Scale = 0;
1810 HasBaseReg = true;
1811 }
1812
1813 return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, BaseOffset,
1814 HasBaseReg, Scale);
1815}
1816
1817static bool isAlwaysFoldable(const TargetTransformInfo &TTI,
1818 ScalarEvolution &SE, int64_t MinOffset,
1819 int64_t MaxOffset, LSRUse::KindType Kind,
1820 MemAccessTy AccessTy, const SCEV *S,
1821 bool HasBaseReg) {
1822 // Fast-path: zero is always foldable.
1823 if (S->isZero()) return true;
1824
1825 // Conservatively, create an address with an immediate and a
1826 // base and a scale.
1827 int64_t BaseOffset = ExtractImmediate(S, SE);
1828 GlobalValue *BaseGV = ExtractSymbol(S, SE);
1829
1830 // If there's anything else involved, it's not foldable.
1831 if (!S->isZero()) return false;
1832
1833 // Fast-path: zero is always foldable.
1834 if (BaseOffset == 0 && !BaseGV) return true;
1835
1836 // Conservatively, create an address with an immediate and a
1837 // base and a scale.
1838 int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1;
1839
1840 return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV,
1841 BaseOffset, HasBaseReg, Scale);
1842}
1843
1844namespace {
1845
1846/// An individual increment in a Chain of IV increments. Relate an IV user to
1847/// an expression that computes the IV it uses from the IV used by the previous
1848/// link in the Chain.
1849///
1850/// For the head of a chain, IncExpr holds the absolute SCEV expression for the
1851/// original IVOperand. The head of the chain's IVOperand is only valid during
1852/// chain collection, before LSR replaces IV users. During chain generation,
1853/// IncExpr can be used to find the new IVOperand that computes the same
1854/// expression.
1855struct IVInc {
1856 Instruction *UserInst;
1857 Value* IVOperand;
1858 const SCEV *IncExpr;
1859
1860 IVInc(Instruction *U, Value *O, const SCEV *E)
1861 : UserInst(U), IVOperand(O), IncExpr(E) {}
1862};
1863
1864// The list of IV increments in program order. We typically add the head of a
1865// chain without finding subsequent links.
1866struct IVChain {
1867 SmallVector<IVInc, 1> Incs;
1868 const SCEV *ExprBase = nullptr;
1869
1870 IVChain() = default;
1871 IVChain(const IVInc &Head, const SCEV *Base)
1872 : Incs(1, Head), ExprBase(Base) {}
1873
1874 using const_iterator = SmallVectorImpl<IVInc>::const_iterator;
1875
1876 // Return the first increment in the chain.
1877 const_iterator begin() const {
1878 assert(!Incs.empty())((!Incs.empty()) ? static_cast<void> (0) : __assert_fail
("!Incs.empty()", "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1878, __PRETTY_FUNCTION__))
;
1879 return std::next(Incs.begin());
1880 }
1881 const_iterator end() const {
1882 return Incs.end();
1883 }
1884
1885 // Returns true if this chain contains any increments.
1886 bool hasIncs() const { return Incs.size() >= 2; }
1887
1888 // Add an IVInc to the end of this chain.
1889 void add(const IVInc &X) { Incs.push_back(X); }
1890
1891 // Returns the last UserInst in the chain.
1892 Instruction *tailUserInst() const { return Incs.back().UserInst; }
1893
1894 // Returns true if IncExpr can be profitably added to this chain.
1895 bool isProfitableIncrement(const SCEV *OperExpr,
1896 const SCEV *IncExpr,
1897 ScalarEvolution&);
1898};
1899
1900/// Helper for CollectChains to track multiple IV increment uses. Distinguish
1901/// between FarUsers that definitely cross IV increments and NearUsers that may
1902/// be used between IV increments.
1903struct ChainUsers {
1904 SmallPtrSet<Instruction*, 4> FarUsers;
1905 SmallPtrSet<Instruction*, 4> NearUsers;
1906};
1907
1908/// This class holds state for the main loop strength reduction logic.
1909class LSRInstance {
1910 IVUsers &IU;
1911 ScalarEvolution &SE;
1912 DominatorTree &DT;
1913 LoopInfo &LI;
1914 AssumptionCache &AC;
1915 TargetLibraryInfo &LibInfo;
1916 const TargetTransformInfo &TTI;
1917 Loop *const L;
1918 bool FavorBackedgeIndex = false;
1919 bool Changed = false;
1920
1921 /// This is the insert position that the current loop's induction variable
1922 /// increment should be placed. In simple loops, this is the latch block's
1923 /// terminator. But in more complicated cases, this is a position which will
1924 /// dominate all the in-loop post-increment users.
1925 Instruction *IVIncInsertPos = nullptr;
1926
1927 /// Interesting factors between use strides.
1928 ///
1929 /// We explicitly use a SetVector which contains a SmallSet, instead of the
1930 /// default, a SmallDenseSet, because we need to use the full range of
1931 /// int64_ts, and there's currently no good way of doing that with
1932 /// SmallDenseSet.
1933 SetVector<int64_t, SmallVector<int64_t, 8>, SmallSet<int64_t, 8>> Factors;
1934
1935 /// Interesting use types, to facilitate truncation reuse.
1936 SmallSetVector<Type *, 4> Types;
1937
1938 /// The list of interesting uses.
1939 mutable SmallVector<LSRUse, 16> Uses;
1940
1941 /// Track which uses use which register candidates.
1942 RegUseTracker RegUses;
1943
1944 // Limit the number of chains to avoid quadratic behavior. We don't expect to
1945 // have more than a few IV increment chains in a loop. Missing a Chain falls
1946 // back to normal LSR behavior for those uses.
1947 static const unsigned MaxChains = 8;
1948
1949 /// IV users can form a chain of IV increments.
1950 SmallVector<IVChain, MaxChains> IVChainVec;
1951
1952 /// IV users that belong to profitable IVChains.
1953 SmallPtrSet<Use*, MaxChains> IVIncSet;
1954
1955 void OptimizeShadowIV();
1956 bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse);
1957 ICmpInst *OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse);
1958 void OptimizeLoopTermCond();
1959
1960 void ChainInstruction(Instruction *UserInst, Instruction *IVOper,
1961 SmallVectorImpl<ChainUsers> &ChainUsersVec);
1962 void FinalizeChain(IVChain &Chain);
1963 void CollectChains();
1964 void GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter,
1965 SmallVectorImpl<WeakTrackingVH> &DeadInsts);
1966
1967 void CollectInterestingTypesAndFactors();
1968 void CollectFixupsAndInitialFormulae();
1969
1970 // Support for sharing of LSRUses between LSRFixups.
1971 using UseMapTy = DenseMap<LSRUse::SCEVUseKindPair, size_t>;
1972 UseMapTy UseMap;
1973
1974 bool reconcileNewOffset(LSRUse &LU, int64_t NewOffset, bool HasBaseReg,
1975 LSRUse::KindType Kind, MemAccessTy AccessTy);
1976
1977 std::pair<size_t, int64_t> getUse(const SCEV *&Expr, LSRUse::KindType Kind,
1978 MemAccessTy AccessTy);
1979
1980 void DeleteUse(LSRUse &LU, size_t LUIdx);
1981
1982 LSRUse *FindUseWithSimilarFormula(const Formula &F, const LSRUse &OrigLU);
1983
1984 void InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx);
1985 void InsertSupplementalFormula(const SCEV *S, LSRUse &LU, size_t LUIdx);
1986 void CountRegisters(const Formula &F, size_t LUIdx);
1987 bool InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F);
1988
1989 void CollectLoopInvariantFixupsAndFormulae();
1990
1991 void GenerateReassociations(LSRUse &LU, unsigned LUIdx, Formula Base,
1992 unsigned Depth = 0);
1993
1994 void GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,
1995 const Formula &Base, unsigned Depth,
1996 size_t Idx, bool IsScaledReg = false);
1997 void GenerateCombinations(LSRUse &LU, unsigned LUIdx, Formula Base);
1998 void GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx,
1999 const Formula &Base, size_t Idx,
2000 bool IsScaledReg = false);
2001 void GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx, Formula Base);
2002 void GenerateConstantOffsetsImpl(LSRUse &LU, unsigned LUIdx,
2003 const Formula &Base,
2004 const SmallVectorImpl<int64_t> &Worklist,
2005 size_t Idx, bool IsScaledReg = false);
2006 void GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx, Formula Base);
2007 void GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, Formula Base);
2008 void GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base);
2009 void GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base);
2010 void GenerateCrossUseConstantOffsets();
2011 void GenerateAllReuseFormulae();
2012
2013 void FilterOutUndesirableDedicatedRegisters();
2014
2015 size_t EstimateSearchSpaceComplexity() const;
2016 void NarrowSearchSpaceByDetectingSupersets();
2017 void NarrowSearchSpaceByCollapsingUnrolledCode();
2018 void NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters();
2019 void NarrowSearchSpaceByFilterFormulaWithSameScaledReg();
2020 void NarrowSearchSpaceByDeletingCostlyFormulas();
2021 void NarrowSearchSpaceByPickingWinnerRegs();
2022 void NarrowSearchSpaceUsingHeuristics();
2023
2024 void SolveRecurse(SmallVectorImpl<const Formula *> &Solution,
2025 Cost &SolutionCost,
2026 SmallVectorImpl<const Formula *> &Workspace,
2027 const Cost &CurCost,
2028 const SmallPtrSet<const SCEV *, 16> &CurRegs,
2029 DenseSet<const SCEV *> &VisitedRegs) const;
2030 void Solve(SmallVectorImpl<const Formula *> &Solution) const;
2031
2032 BasicBlock::iterator
2033 HoistInsertPosition(BasicBlock::iterator IP,
2034 const SmallVectorImpl<Instruction *> &Inputs) const;
2035 BasicBlock::iterator
2036 AdjustInsertPositionForExpand(BasicBlock::iterator IP,
2037 const LSRFixup &LF,
2038 const LSRUse &LU,
2039 SCEVExpander &Rewriter) const;
2040
2041 Value *Expand(const LSRUse &LU, const LSRFixup &LF, const Formula &F,
2042 BasicBlock::iterator IP, SCEVExpander &Rewriter,
2043 SmallVectorImpl<WeakTrackingVH> &DeadInsts) const;
2044 void RewriteForPHI(PHINode *PN, const LSRUse &LU, const LSRFixup &LF,
2045 const Formula &F, SCEVExpander &Rewriter,
2046 SmallVectorImpl<WeakTrackingVH> &DeadInsts) const;
2047 void Rewrite(const LSRUse &LU, const LSRFixup &LF, const Formula &F,
2048 SCEVExpander &Rewriter,
2049 SmallVectorImpl<WeakTrackingVH> &DeadInsts) const;
2050 void ImplementSolution(const SmallVectorImpl<const Formula *> &Solution);
2051
2052public:
2053 LSRInstance(Loop *L, IVUsers &IU, ScalarEvolution &SE, DominatorTree &DT,
2054 LoopInfo &LI, const TargetTransformInfo &TTI, AssumptionCache &AC,
2055 TargetLibraryInfo &LibInfo);
2056
2057 bool getChanged() const { return Changed; }
2058
2059 void print_factors_and_types(raw_ostream &OS) const;
2060 void print_fixups(raw_ostream &OS) const;
2061 void print_uses(raw_ostream &OS) const;
2062 void print(raw_ostream &OS) const;
2063 void dump() const;
2064};
2065
2066} // end anonymous namespace
2067
2068/// If IV is used in a int-to-float cast inside the loop then try to eliminate
2069/// the cast operation.
2070void LSRInstance::OptimizeShadowIV() {
2071 const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);
2072 if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))
2073 return;
2074
2075 for (IVUsers::const_iterator UI = IU.begin(), E = IU.end();
2076 UI != E; /* empty */) {
2077 IVUsers::const_iterator CandidateUI = UI;
2078 ++UI;
2079 Instruction *ShadowUse = CandidateUI->getUser();
2080 Type *DestTy = nullptr;
2081 bool IsSigned = false;
2082
2083 /* If shadow use is a int->float cast then insert a second IV
2084 to eliminate this cast.
2085
2086 for (unsigned i = 0; i < n; ++i)
2087 foo((double)i);
2088
2089 is transformed into
2090
2091 double d = 0.0;
2092 for (unsigned i = 0; i < n; ++i, ++d)
2093 foo(d);
2094 */
2095 if (UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->getUser())) {
2096 IsSigned = false;
2097 DestTy = UCast->getDestTy();
2098 }
2099 else if (SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->getUser())) {
2100 IsSigned = true;
2101 DestTy = SCast->getDestTy();
2102 }
2103 if (!DestTy) continue;
2104
2105 // If target does not support DestTy natively then do not apply
2106 // this transformation.
2107 if (!TTI.isTypeLegal(DestTy)) continue;
2108
2109 PHINode *PH = dyn_cast<PHINode>(ShadowUse->getOperand(0));
2110 if (!PH) continue;
2111 if (PH->getNumIncomingValues() != 2) continue;
2112
2113 // If the calculation in integers overflows, the result in FP type will
2114 // differ. So we only can do this transformation if we are guaranteed to not
2115 // deal with overflowing values
2116 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SE.getSCEV(PH));
2117 if (!AR) continue;
2118 if (IsSigned && !AR->hasNoSignedWrap()) continue;
2119 if (!IsSigned && !AR->hasNoUnsignedWrap()) continue;
2120
2121 Type *SrcTy = PH->getType();
2122 int Mantissa = DestTy->getFPMantissaWidth();
2123 if (Mantissa == -1) continue;
2124 if ((int)SE.getTypeSizeInBits(SrcTy) > Mantissa)
2125 continue;
2126
2127 unsigned Entry, Latch;
2128 if (PH->getIncomingBlock(0) == L->getLoopPreheader()) {
2129 Entry = 0;
2130 Latch = 1;
2131 } else {
2132 Entry = 1;
2133 Latch = 0;
2134 }
2135
2136 ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry));
2137 if (!Init) continue;
2138 Constant *NewInit = ConstantFP::get(DestTy, IsSigned ?
2139 (double)Init->getSExtValue() :
2140 (double)Init->getZExtValue());
2141
2142 BinaryOperator *Incr =
2143 dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch));
2144 if (!Incr) continue;
2145 if (Incr->getOpcode() != Instruction::Add
2146 && Incr->getOpcode() != Instruction::Sub)
2147 continue;
2148
2149 /* Initialize new IV, double d = 0.0 in above example. */
2150 ConstantInt *C = nullptr;
2151 if (Incr->getOperand(0) == PH)
2152 C = dyn_cast<ConstantInt>(Incr->getOperand(1));
2153 else if (Incr->getOperand(1) == PH)
2154 C = dyn_cast<ConstantInt>(Incr->getOperand(0));
2155 else
2156 continue;
2157
2158 if (!C) continue;
2159
2160 // Ignore negative constants, as the code below doesn't handle them
2161 // correctly. TODO: Remove this restriction.
2162 if (!C->getValue().isStrictlyPositive()) continue;
2163
2164 /* Add new PHINode. */
2165 PHINode *NewPH = PHINode::Create(DestTy, 2, "IV.S.", PH);
2166
2167 /* create new increment. '++d' in above example. */
2168 Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue());
2169 BinaryOperator *NewIncr =
2170 BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ?
2171 Instruction::FAdd : Instruction::FSub,
2172 NewPH, CFP, "IV.S.next.", Incr);
2173
2174 NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry));
2175 NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch));
2176
2177 /* Remove cast operation */
2178 ShadowUse->replaceAllUsesWith(NewPH);
2179 ShadowUse->eraseFromParent();
2180 Changed = true;
2181 break;
2182 }
2183}
2184
2185/// If Cond has an operand that is an expression of an IV, set the IV user and
2186/// stride information and return true, otherwise return false.
2187bool LSRInstance::FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse) {
2188 for (IVStrideUse &U : IU)
2189 if (U.getUser() == Cond) {
2190 // NOTE: we could handle setcc instructions with multiple uses here, but
2191 // InstCombine does it as well for simple uses, it's not clear that it
2192 // occurs enough in real life to handle.
2193 CondUse = &U;
2194 return true;
2195 }
2196 return false;
2197}
2198
2199/// Rewrite the loop's terminating condition if it uses a max computation.
2200///
2201/// This is a narrow solution to a specific, but acute, problem. For loops
2202/// like this:
2203///
2204/// i = 0;
2205/// do {
2206/// p[i] = 0.0;
2207/// } while (++i < n);
2208///
2209/// the trip count isn't just 'n', because 'n' might not be positive. And
2210/// unfortunately this can come up even for loops where the user didn't use
2211/// a C do-while loop. For example, seemingly well-behaved top-test loops
2212/// will commonly be lowered like this:
2213///
2214/// if (n > 0) {
2215/// i = 0;
2216/// do {
2217/// p[i] = 0.0;
2218/// } while (++i < n);
2219/// }
2220///
2221/// and then it's possible for subsequent optimization to obscure the if
2222/// test in such a way that indvars can't find it.
2223///
2224/// When indvars can't find the if test in loops like this, it creates a
2225/// max expression, which allows it to give the loop a canonical
2226/// induction variable:
2227///
2228/// i = 0;
2229/// max = n < 1 ? 1 : n;
2230/// do {
2231/// p[i] = 0.0;
2232/// } while (++i != max);
2233///
2234/// Canonical induction variables are necessary because the loop passes
2235/// are designed around them. The most obvious example of this is the
2236/// LoopInfo analysis, which doesn't remember trip count values. It
2237/// expects to be able to rediscover the trip count each time it is
2238/// needed, and it does this using a simple analysis that only succeeds if
2239/// the loop has a canonical induction variable.
2240///
2241/// However, when it comes time to generate code, the maximum operation
2242/// can be quite costly, especially if it's inside of an outer loop.
2243///
2244/// This function solves this problem by detecting this type of loop and
2245/// rewriting their conditions from ICMP_NE back to ICMP_SLT, and deleting
2246/// the instructions for the maximum computation.
2247ICmpInst *LSRInstance::OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse) {
2248 // Check that the loop matches the pattern we're looking for.
2249 if (Cond->getPredicate() != CmpInst::ICMP_EQ &&
2250 Cond->getPredicate() != CmpInst::ICMP_NE)
2251 return Cond;
2252
2253 SelectInst *Sel = dyn_cast<SelectInst>(Cond->getOperand(1));
2254 if (!Sel || !Sel->hasOneUse()) return Cond;
2255
2256 const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);
2257 if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))
2258 return Cond;
2259 const SCEV *One = SE.getConstant(BackedgeTakenCount->getType(), 1);
2260
2261 // Add one to the backedge-taken count to get the trip count.
2262 const SCEV *IterationCount = SE.getAddExpr(One, BackedgeTakenCount);
2263 if (IterationCount != SE.getSCEV(Sel)) return Cond;
2264
2265 // Check for a max calculation that matches the pattern. There's no check
2266 // for ICMP_ULE here because the comparison would be with zero, which
2267 // isn't interesting.
2268 CmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
2269 const SCEVNAryExpr *Max = nullptr;
2270 if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(BackedgeTakenCount)) {
2271 Pred = ICmpInst::ICMP_SLE;
2272 Max = S;
2273 } else if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(IterationCount)) {
2274 Pred = ICmpInst::ICMP_SLT;
2275 Max = S;
2276 } else if (const SCEVUMaxExpr *U = dyn_cast<SCEVUMaxExpr>(IterationCount)) {
2277 Pred = ICmpInst::ICMP_ULT;
2278 Max = U;
2279 } else {
2280 // No match; bail.
2281 return Cond;
2282 }
2283
2284 // To handle a max with more than two operands, this optimization would
2285 // require additional checking and setup.
2286 if (Max->getNumOperands() != 2)
2287 return Cond;
2288
2289 const SCEV *MaxLHS = Max->getOperand(0);
2290 const SCEV *MaxRHS = Max->getOperand(1);
2291
2292 // ScalarEvolution canonicalizes constants to the left. For < and >, look
2293 // for a comparison with 1. For <= and >=, a comparison with zero.
2294 if (!MaxLHS ||
2295 (ICmpInst::isTrueWhenEqual(Pred) ? !MaxLHS->isZero() : (MaxLHS != One)))
2296 return Cond;
2297
2298 // Check the relevant induction variable for conformance to
2299 // the pattern.
2300 const SCEV *IV = SE.getSCEV(Cond->getOperand(0));
2301 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(IV);
2302 if (!AR || !AR->isAffine() ||
2303 AR->getStart() != One ||
2304 AR->getStepRecurrence(SE) != One)
2305 return Cond;
2306
2307 assert(AR->getLoop() == L &&((AR->getLoop() == L && "Loop condition operand is an addrec in a different loop!"
) ? static_cast<void> (0) : __assert_fail ("AR->getLoop() == L && \"Loop condition operand is an addrec in a different loop!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2308, __PRETTY_FUNCTION__))
2308 "Loop condition operand is an addrec in a different loop!")((AR->getLoop() == L && "Loop condition operand is an addrec in a different loop!"
) ? static_cast<void> (0) : __assert_fail ("AR->getLoop() == L && \"Loop condition operand is an addrec in a different loop!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2308, __PRETTY_FUNCTION__))
;
2309
2310 // Check the right operand of the select, and remember it, as it will
2311 // be used in the new comparison instruction.
2312 Value *NewRHS = nullptr;
2313 if (ICmpInst::isTrueWhenEqual(Pred)) {
2314 // Look for n+1, and grab n.
2315 if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(1)))
2316 if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1)))
2317 if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS)
2318 NewRHS = BO->getOperand(0);
2319 if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(2)))
2320 if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1)))
2321 if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS)
2322 NewRHS = BO->getOperand(0);
2323 if (!NewRHS)
2324 return Cond;
2325 } else if (SE.getSCEV(Sel->getOperand(1)) == MaxRHS)
2326 NewRHS = Sel->getOperand(1);
2327 else if (SE.getSCEV(Sel->getOperand(2)) == MaxRHS)
2328 NewRHS = Sel->getOperand(2);
2329 else if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(MaxRHS))
2330 NewRHS = SU->getValue();
2331 else
2332 // Max doesn't match expected pattern.
2333 return Cond;
2334
2335 // Determine the new comparison opcode. It may be signed or unsigned,
2336 // and the original comparison may be either equality or inequality.
2337 if (Cond->getPredicate() == CmpInst::ICMP_EQ)
2338 Pred = CmpInst::getInversePredicate(Pred);
2339
2340 // Ok, everything looks ok to change the condition into an SLT or SGE and
2341 // delete the max calculation.
2342 ICmpInst *NewCond =
2343 new ICmpInst(Cond, Pred, Cond->getOperand(0), NewRHS, "scmp");
2344
2345 // Delete the max calculation instructions.
2346 Cond->replaceAllUsesWith(NewCond);
2347 CondUse->setUser(NewCond);
2348 Instruction *Cmp = cast<Instruction>(Sel->getOperand(0));
2349 Cond->eraseFromParent();
2350 Sel->eraseFromParent();
2351 if (Cmp->use_empty())
2352 Cmp->eraseFromParent();
2353 return NewCond;
2354}
2355
2356/// Change loop terminating condition to use the postinc iv when possible.
2357void
2358LSRInstance::OptimizeLoopTermCond() {
2359 SmallPtrSet<Instruction *, 4> PostIncs;
2360
2361 // We need a different set of heuristics for rotated and non-rotated loops.
2362 // If a loop is rotated then the latch is also the backedge, so inserting
2363 // post-inc expressions just before the latch is ideal. To reduce live ranges
2364 // it also makes sense to rewrite terminating conditions to use post-inc
2365 // expressions.
2366 //
2367 // If the loop is not rotated then the latch is not a backedge; the latch
2368 // check is done in the loop head. Adding post-inc expressions before the
2369 // latch will cause overlapping live-ranges of pre-inc and post-inc expressions
2370 // in the loop body. In this case we do *not* want to use post-inc expressions
2371 // in the latch check, and we want to insert post-inc expressions before
2372 // the backedge.
2373 BasicBlock *LatchBlock = L->getLoopLatch();
2374 SmallVector<BasicBlock*, 8> ExitingBlocks;
2375 L->getExitingBlocks(ExitingBlocks);
2376 if (llvm::all_of(ExitingBlocks, [&LatchBlock](const BasicBlock *BB) {
2377 return LatchBlock != BB;
2378 })) {
2379 // The backedge doesn't exit the loop; treat this as a head-tested loop.
2380 IVIncInsertPos = LatchBlock->getTerminator();
2381 return;
2382 }
2383
2384 // Otherwise treat this as a rotated loop.
2385 for (BasicBlock *ExitingBlock : ExitingBlocks) {
2386 // Get the terminating condition for the loop if possible. If we
2387 // can, we want to change it to use a post-incremented version of its
2388 // induction variable, to allow coalescing the live ranges for the IV into
2389 // one register value.
2390
2391 BranchInst *TermBr = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
2392 if (!TermBr)
2393 continue;
2394 // FIXME: Overly conservative, termination condition could be an 'or' etc..
2395 if (TermBr->isUnconditional() || !isa<ICmpInst>(TermBr->getCondition()))
2396 continue;
2397
2398 // Search IVUsesByStride to find Cond's IVUse if there is one.
2399 IVStrideUse *CondUse = nullptr;
2400 ICmpInst *Cond = cast<ICmpInst>(TermBr->getCondition());
2401 if (!FindIVUserForCond(Cond, CondUse))
2402 continue;
2403
2404 // If the trip count is computed in terms of a max (due to ScalarEvolution
2405 // being unable to find a sufficient guard, for example), change the loop
2406 // comparison to use SLT or ULT instead of NE.
2407 // One consequence of doing this now is that it disrupts the count-down
2408 // optimization. That's not always a bad thing though, because in such
2409 // cases it may still be worthwhile to avoid a max.
2410 Cond = OptimizeMax(Cond, CondUse);
2411
2412 // If this exiting block dominates the latch block, it may also use
2413 // the post-inc value if it won't be shared with other uses.
2414 // Check for dominance.
2415 if (!DT.dominates(ExitingBlock, LatchBlock))
2416 continue;
2417
2418 // Conservatively avoid trying to use the post-inc value in non-latch
2419 // exits if there may be pre-inc users in intervening blocks.
2420 if (LatchBlock != ExitingBlock)
2421 for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI)
2422 // Test if the use is reachable from the exiting block. This dominator
2423 // query is a conservative approximation of reachability.
2424 if (&*UI != CondUse &&
2425 !DT.properlyDominates(UI->getUser()->getParent(), ExitingBlock)) {
2426 // Conservatively assume there may be reuse if the quotient of their
2427 // strides could be a legal scale.
2428 const SCEV *A = IU.getStride(*CondUse, L);
2429 const SCEV *B = IU.getStride(*UI, L);
2430 if (!A || !B) continue;
2431 if (SE.getTypeSizeInBits(A->getType()) !=
2432 SE.getTypeSizeInBits(B->getType())) {
2433 if (SE.getTypeSizeInBits(A->getType()) >
2434 SE.getTypeSizeInBits(B->getType()))
2435 B = SE.getSignExtendExpr(B, A->getType());
2436 else
2437 A = SE.getSignExtendExpr(A, B->getType());
2438 }
2439 if (const SCEVConstant *D =
2440 dyn_cast_or_null<SCEVConstant>(getExactSDiv(B, A, SE))) {
2441 const ConstantInt *C = D->getValue();
2442 // Stride of one or negative one can have reuse with non-addresses.
2443 if (C->isOne() || C->isMinusOne())
2444 goto decline_post_inc;
2445 // Avoid weird situations.
2446 if (C->getValue().getMinSignedBits() >= 64 ||
2447 C->getValue().isMinSignedValue())
2448 goto decline_post_inc;
2449 // Check for possible scaled-address reuse.
2450 if (isAddressUse(TTI, UI->getUser(), UI->getOperandValToReplace())) {
2451 MemAccessTy AccessTy = getAccessType(
2452 TTI, UI->getUser(), UI->getOperandValToReplace());
2453 int64_t Scale = C->getSExtValue();
2454 if (TTI.isLegalAddressingMode(AccessTy.MemTy, /*BaseGV=*/nullptr,
2455 /*BaseOffset=*/0,
2456 /*HasBaseReg=*/false, Scale,
2457 AccessTy.AddrSpace))
2458 goto decline_post_inc;
2459 Scale = -Scale;
2460 if (TTI.isLegalAddressingMode(AccessTy.MemTy, /*BaseGV=*/nullptr,
2461 /*BaseOffset=*/0,
2462 /*HasBaseReg=*/false, Scale,
2463 AccessTy.AddrSpace))
2464 goto decline_post_inc;
2465 }
2466 }
2467 }
2468
2469 LLVM_DEBUG(dbgs() << " Change loop exiting icmp to use postinc iv: "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Change loop exiting icmp to use postinc iv: "
<< *Cond << '\n'; } } while (false)
2470 << *Cond << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Change loop exiting icmp to use postinc iv: "
<< *Cond << '\n'; } } while (false)
;
2471
2472 // It's possible for the setcc instruction to be anywhere in the loop, and
2473 // possible for it to have multiple users. If it is not immediately before
2474 // the exiting block branch, move it.
2475 if (&*++BasicBlock::iterator(Cond) != TermBr) {
2476 if (Cond->hasOneUse()) {
2477 Cond->moveBefore(TermBr);
2478 } else {
2479 // Clone the terminating condition and insert into the loopend.
2480 ICmpInst *OldCond = Cond;
2481 Cond = cast<ICmpInst>(Cond->clone());
2482 Cond->setName(L->getHeader()->getName() + ".termcond");
2483 ExitingBlock->getInstList().insert(TermBr->getIterator(), Cond);
2484
2485 // Clone the IVUse, as the old use still exists!
2486 CondUse = &IU.AddUser(Cond, CondUse->getOperandValToReplace());
2487 TermBr->replaceUsesOfWith(OldCond, Cond);
2488 }
2489 }
2490
2491 // If we get to here, we know that we can transform the setcc instruction to
2492 // use the post-incremented version of the IV, allowing us to coalesce the
2493 // live ranges for the IV correctly.
2494 CondUse->transformToPostInc(L);
2495 Changed = true;
2496
2497 PostIncs.insert(Cond);
2498 decline_post_inc:;
2499 }
2500
2501 // Determine an insertion point for the loop induction variable increment. It
2502 // must dominate all the post-inc comparisons we just set up, and it must
2503 // dominate the loop latch edge.
2504 IVIncInsertPos = L->getLoopLatch()->getTerminator();
2505 for (Instruction *Inst : PostIncs) {
2506 BasicBlock *BB =
2507 DT.findNearestCommonDominator(IVIncInsertPos->getParent(),
2508 Inst->getParent());
2509 if (BB == Inst->getParent())
2510 IVIncInsertPos = Inst;
2511 else if (BB != IVIncInsertPos->getParent())
2512 IVIncInsertPos = BB->getTerminator();
2513 }
2514}
2515
2516/// Determine if the given use can accommodate a fixup at the given offset and
2517/// other details. If so, update the use and return true.
2518bool LSRInstance::reconcileNewOffset(LSRUse &LU, int64_t NewOffset,
2519 bool HasBaseReg, LSRUse::KindType Kind,
2520 MemAccessTy AccessTy) {
2521 int64_t NewMinOffset = LU.MinOffset;
2522 int64_t NewMaxOffset = LU.MaxOffset;
2523 MemAccessTy NewAccessTy = AccessTy;
2524
2525 // Check for a mismatched kind. It's tempting to collapse mismatched kinds to
2526 // something conservative, however this can pessimize in the case that one of
2527 // the uses will have all its uses outside the loop, for example.
2528 if (LU.Kind != Kind)
2529 return false;
2530
2531 // Check for a mismatched access type, and fall back conservatively as needed.
2532 // TODO: Be less conservative when the type is similar and can use the same
2533 // addressing modes.
2534 if (Kind == LSRUse::Address) {
2535 if (AccessTy.MemTy != LU.AccessTy.MemTy) {
2536 NewAccessTy = MemAccessTy::getUnknown(AccessTy.MemTy->getContext(),
2537 AccessTy.AddrSpace);
2538 }
2539 }
2540
2541 // Conservatively assume HasBaseReg is true for now.
2542 if (NewOffset < LU.MinOffset) {
2543 if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr,
2544 LU.MaxOffset - NewOffset, HasBaseReg))
2545 return false;
2546 NewMinOffset = NewOffset;
2547 } else if (NewOffset > LU.MaxOffset) {
2548 if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr,
2549 NewOffset - LU.MinOffset, HasBaseReg))
2550 return false;
2551 NewMaxOffset = NewOffset;
2552 }
2553
2554 // Update the use.
2555 LU.MinOffset = NewMinOffset;
2556 LU.MaxOffset = NewMaxOffset;
2557 LU.AccessTy = NewAccessTy;
2558 return true;
2559}
2560
2561/// Return an LSRUse index and an offset value for a fixup which needs the given
2562/// expression, with the given kind and optional access type. Either reuse an
2563/// existing use or create a new one, as needed.
2564std::pair<size_t, int64_t> LSRInstance::getUse(const SCEV *&Expr,
2565 LSRUse::KindType Kind,
2566 MemAccessTy AccessTy) {
2567 const SCEV *Copy = Expr;
2568 int64_t Offset = ExtractImmediate(Expr, SE);
2569
2570 // Basic uses can't accept any offset, for example.
2571 if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ nullptr,
2572 Offset, /*HasBaseReg=*/ true)) {
2573 Expr = Copy;
2574 Offset = 0;
2575 }
2576
2577 std::pair<UseMapTy::iterator, bool> P =
2578 UseMap.insert(std::make_pair(LSRUse::SCEVUseKindPair(Expr, Kind), 0));
2579 if (!P.second) {
2580 // A use already existed with this base.
2581 size_t LUIdx = P.first->second;
2582 LSRUse &LU = Uses[LUIdx];
2583 if (reconcileNewOffset(LU, Offset, /*HasBaseReg=*/true, Kind, AccessTy))
2584 // Reuse this use.
2585 return std::make_pair(LUIdx, Offset);
2586 }
2587
2588 // Create a new use.
2589 size_t LUIdx = Uses.size();
2590 P.first->second = LUIdx;
2591 Uses.push_back(LSRUse(Kind, AccessTy));
2592 LSRUse &LU = Uses[LUIdx];
2593
2594 LU.MinOffset = Offset;
2595 LU.MaxOffset = Offset;
2596 return std::make_pair(LUIdx, Offset);
2597}
2598
2599/// Delete the given use from the Uses list.
2600void LSRInstance::DeleteUse(LSRUse &LU, size_t LUIdx) {
2601 if (&LU != &Uses.back())
2602 std::swap(LU, Uses.back());
2603 Uses.pop_back();
2604
2605 // Update RegUses.
2606 RegUses.swapAndDropUse(LUIdx, Uses.size());
2607}
2608
2609/// Look for a use distinct from OrigLU which is has a formula that has the same
2610/// registers as the given formula.
2611LSRUse *
2612LSRInstance::FindUseWithSimilarFormula(const Formula &OrigF,
2613 const LSRUse &OrigLU) {
2614 // Search all uses for the formula. This could be more clever.
2615 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
2616 LSRUse &LU = Uses[LUIdx];
2617 // Check whether this use is close enough to OrigLU, to see whether it's
2618 // worthwhile looking through its formulae.
2619 // Ignore ICmpZero uses because they may contain formulae generated by
2620 // GenerateICmpZeroScales, in which case adding fixup offsets may
2621 // be invalid.
2622 if (&LU != &OrigLU &&
2623 LU.Kind != LSRUse::ICmpZero &&
2624 LU.Kind == OrigLU.Kind && OrigLU.AccessTy == LU.AccessTy &&
2625 LU.WidestFixupType == OrigLU.WidestFixupType &&
2626 LU.HasFormulaWithSameRegs(OrigF)) {
2627 // Scan through this use's formulae.
2628 for (const Formula &F : LU.Formulae) {
2629 // Check to see if this formula has the same registers and symbols
2630 // as OrigF.
2631 if (F.BaseRegs == OrigF.BaseRegs &&
2632 F.ScaledReg == OrigF.ScaledReg &&
2633 F.BaseGV == OrigF.BaseGV &&
2634 F.Scale == OrigF.Scale &&
2635 F.UnfoldedOffset == OrigF.UnfoldedOffset) {
2636 if (F.BaseOffset == 0)
2637 return &LU;
2638 // This is the formula where all the registers and symbols matched;
2639 // there aren't going to be any others. Since we declined it, we
2640 // can skip the rest of the formulae and proceed to the next LSRUse.
2641 break;
2642 }
2643 }
2644 }
2645 }
2646
2647 // Nothing looked good.
2648 return nullptr;
2649}
2650
2651void LSRInstance::CollectInterestingTypesAndFactors() {
2652 SmallSetVector<const SCEV *, 4> Strides;
2653
2654 // Collect interesting types and strides.
2655 SmallVector<const SCEV *, 4> Worklist;
2656 for (const IVStrideUse &U : IU) {
2657 const SCEV *Expr = IU.getExpr(U);
2658
2659 // Collect interesting types.
2660 Types.insert(SE.getEffectiveSCEVType(Expr->getType()));
2661
2662 // Add strides for mentioned loops.
2663 Worklist.push_back(Expr);
2664 do {
2665 const SCEV *S = Worklist.pop_back_val();
2666 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
2667 if (AR->getLoop() == L)
2668 Strides.insert(AR->getStepRecurrence(SE));
2669 Worklist.push_back(AR->getStart());
2670 } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
2671 Worklist.append(Add->op_begin(), Add->op_end());
2672 }
2673 } while (!Worklist.empty());
2674 }
2675
2676 // Compute interesting factors from the set of interesting strides.
2677 for (SmallSetVector<const SCEV *, 4>::const_iterator
2678 I = Strides.begin(), E = Strides.end(); I != E; ++I)
2679 for (SmallSetVector<const SCEV *, 4>::const_iterator NewStrideIter =
2680 std::next(I); NewStrideIter != E; ++NewStrideIter) {
2681 const SCEV *OldStride = *I;
2682 const SCEV *NewStride = *NewStrideIter;
2683
2684 if (SE.getTypeSizeInBits(OldStride->getType()) !=
2685 SE.getTypeSizeInBits(NewStride->getType())) {
2686 if (SE.getTypeSizeInBits(OldStride->getType()) >
2687 SE.getTypeSizeInBits(NewStride->getType()))
2688 NewStride = SE.getSignExtendExpr(NewStride, OldStride->getType());
2689 else
2690 OldStride = SE.getSignExtendExpr(OldStride, NewStride->getType());
2691 }
2692 if (const SCEVConstant *Factor =
2693 dyn_cast_or_null<SCEVConstant>(getExactSDiv(NewStride, OldStride,
2694 SE, true))) {
2695 if (Factor->getAPInt().getMinSignedBits() <= 64)
2696 Factors.insert(Factor->getAPInt().getSExtValue());
2697 } else if (const SCEVConstant *Factor =
2698 dyn_cast_or_null<SCEVConstant>(getExactSDiv(OldStride,
2699 NewStride,
2700 SE, true))) {
2701 if (Factor->getAPInt().getMinSignedBits() <= 64)
2702 Factors.insert(Factor->getAPInt().getSExtValue());
2703 }
2704 }
2705
2706 // If all uses use the same type, don't bother looking for truncation-based
2707 // reuse.
2708 if (Types.size() == 1)
2709 Types.clear();
2710
2711 LLVM_DEBUG(print_factors_and_types(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { print_factors_and_types(dbgs()); } } while
(false)
;
2712}
2713
2714/// Helper for CollectChains that finds an IV operand (computed by an AddRec in
2715/// this loop) within [OI,OE) or returns OE. If IVUsers mapped Instructions to
2716/// IVStrideUses, we could partially skip this.
2717static User::op_iterator
2718findIVOperand(User::op_iterator OI, User::op_iterator OE,
2719 Loop *L, ScalarEvolution &SE) {
2720 for(; OI != OE; ++OI) {
2721 if (Instruction *Oper = dyn_cast<Instruction>(*OI)) {
2722 if (!SE.isSCEVable(Oper->getType()))
2723 continue;
2724
2725 if (const SCEVAddRecExpr *AR =
2726 dyn_cast<SCEVAddRecExpr>(SE.getSCEV(Oper))) {
2727 if (AR->getLoop() == L)
2728 break;
2729 }
2730 }
2731 }
2732 return OI;
2733}
2734
2735/// IVChain logic must consistently peek base TruncInst operands, so wrap it in
2736/// a convenient helper.
2737static Value *getWideOperand(Value *Oper) {
2738 if (TruncInst *Trunc = dyn_cast<TruncInst>(Oper))
2739 return Trunc->getOperand(0);
2740 return Oper;
2741}
2742
2743/// Return true if we allow an IV chain to include both types.
2744static bool isCompatibleIVType(Value *LVal, Value *RVal) {
2745 Type *LType = LVal->getType();
2746 Type *RType = RVal->getType();
2747 return (LType == RType) || (LType->isPointerTy() && RType->isPointerTy() &&
2748 // Different address spaces means (possibly)
2749 // different types of the pointer implementation,
2750 // e.g. i16 vs i32 so disallow that.
2751 (LType->getPointerAddressSpace() ==
2752 RType->getPointerAddressSpace()));
2753}
2754
2755/// Return an approximation of this SCEV expression's "base", or NULL for any
2756/// constant. Returning the expression itself is conservative. Returning a
2757/// deeper subexpression is more precise and valid as long as it isn't less
2758/// complex than another subexpression. For expressions involving multiple
2759/// unscaled values, we need to return the pointer-type SCEVUnknown. This avoids
2760/// forming chains across objects, such as: PrevOper==a[i], IVOper==b[i],
2761/// IVInc==b-a.
2762///
2763/// Since SCEVUnknown is the rightmost type, and pointers are the rightmost
2764/// SCEVUnknown, we simply return the rightmost SCEV operand.
2765static const SCEV *getExprBase(const SCEV *S) {
2766 switch (S->getSCEVType()) {
2767 default: // uncluding scUnknown.
2768 return S;
2769 case scConstant:
2770 return nullptr;
2771 case scTruncate:
2772 return getExprBase(cast<SCEVTruncateExpr>(S)->getOperand());
2773 case scZeroExtend:
2774 return getExprBase(cast<SCEVZeroExtendExpr>(S)->getOperand());
2775 case scSignExtend:
2776 return getExprBase(cast<SCEVSignExtendExpr>(S)->getOperand());
2777 case scAddExpr: {
2778 // Skip over scaled operands (scMulExpr) to follow add operands as long as
2779 // there's nothing more complex.
2780 // FIXME: not sure if we want to recognize negation.
2781 const SCEVAddExpr *Add = cast<SCEVAddExpr>(S);
2782 for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(Add->op_end()),
2783 E(Add->op_begin()); I != E; ++I) {
2784 const SCEV *SubExpr = *I;
2785 if (SubExpr->getSCEVType() == scAddExpr)
2786 return getExprBase(SubExpr);
2787
2788 if (SubExpr->getSCEVType() != scMulExpr)
2789 return SubExpr;
2790 }
2791 return S; // all operands are scaled, be conservative.
2792 }
2793 case scAddRecExpr:
2794 return getExprBase(cast<SCEVAddRecExpr>(S)->getStart());
2795 }
2796}
2797
2798/// Return true if the chain increment is profitable to expand into a loop
2799/// invariant value, which may require its own register. A profitable chain
2800/// increment will be an offset relative to the same base. We allow such offsets
2801/// to potentially be used as chain increment as long as it's not obviously
2802/// expensive to expand using real instructions.
2803bool IVChain::isProfitableIncrement(const SCEV *OperExpr,
2804 const SCEV *IncExpr,
2805 ScalarEvolution &SE) {
2806 // Aggressively form chains when -stress-ivchain.
2807 if (StressIVChain)
2808 return true;
2809
2810 // Do not replace a constant offset from IV head with a nonconstant IV
2811 // increment.
2812 if (!isa<SCEVConstant>(IncExpr)) {
2813 const SCEV *HeadExpr = SE.getSCEV(getWideOperand(Incs[0].IVOperand));
2814 if (isa<SCEVConstant>(SE.getMinusSCEV(OperExpr, HeadExpr)))
2815 return false;
2816 }
2817
2818 SmallPtrSet<const SCEV*, 8> Processed;
2819 return !isHighCostExpansion(IncExpr, Processed, SE);
2820}
2821
2822/// Return true if the number of registers needed for the chain is estimated to
2823/// be less than the number required for the individual IV users. First prohibit
2824/// any IV users that keep the IV live across increments (the Users set should
2825/// be empty). Next count the number and type of increments in the chain.
2826///
2827/// Chaining IVs can lead to considerable code bloat if ISEL doesn't
2828/// effectively use postinc addressing modes. Only consider it profitable it the
2829/// increments can be computed in fewer registers when chained.
2830///
2831/// TODO: Consider IVInc free if it's already used in another chains.
2832static bool
2833isProfitableChain(IVChain &Chain, SmallPtrSetImpl<Instruction*> &Users,
2834 ScalarEvolution &SE) {
2835 if (StressIVChain)
2836 return true;
2837
2838 if (!Chain.hasIncs())
2839 return false;
2840
2841 if (!Users.empty()) {
2842 LLVM_DEBUG(dbgs() << "Chain: " << *Chain.Incs[0].UserInst << " users:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " users:\n"; for (Instruction *Inst
: Users) { dbgs() << " " << *Inst << "\n"
; }; } } while (false)
2843 for (Instruction *Instdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " users:\n"; for (Instruction *Inst
: Users) { dbgs() << " " << *Inst << "\n"
; }; } } while (false)
2844 : Users) { dbgs() << " " << *Inst << "\n"; })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " users:\n"; for (Instruction *Inst
: Users) { dbgs() << " " << *Inst << "\n"
; }; } } while (false)
;
2845 return false;
2846 }
2847 assert(!Chain.Incs.empty() && "empty IV chains are not allowed")((!Chain.Incs.empty() && "empty IV chains are not allowed"
) ? static_cast<void> (0) : __assert_fail ("!Chain.Incs.empty() && \"empty IV chains are not allowed\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2847, __PRETTY_FUNCTION__))
;
2848
2849 // The chain itself may require a register, so intialize cost to 1.
2850 int cost = 1;
2851
2852 // A complete chain likely eliminates the need for keeping the original IV in
2853 // a register. LSR does not currently know how to form a complete chain unless
2854 // the header phi already exists.
2855 if (isa<PHINode>(Chain.tailUserInst())
2856 && SE.getSCEV(Chain.tailUserInst()) == Chain.Incs[0].IncExpr) {
2857 --cost;
2858 }
2859 const SCEV *LastIncExpr = nullptr;
2860 unsigned NumConstIncrements = 0;
2861 unsigned NumVarIncrements = 0;
2862 unsigned NumReusedIncrements = 0;
2863 for (const IVInc &Inc : Chain) {
2864 if (Inc.IncExpr->isZero())
2865 continue;
2866
2867 // Incrementing by zero or some constant is neutral. We assume constants can
2868 // be folded into an addressing mode or an add's immediate operand.
2869 if (isa<SCEVConstant>(Inc.IncExpr)) {
2870 ++NumConstIncrements;
2871 continue;
2872 }
2873
2874 if (Inc.IncExpr == LastIncExpr)
2875 ++NumReusedIncrements;
2876 else
2877 ++NumVarIncrements;
2878
2879 LastIncExpr = Inc.IncExpr;
2880 }
2881 // An IV chain with a single increment is handled by LSR's postinc
2882 // uses. However, a chain with multiple increments requires keeping the IV's
2883 // value live longer than it needs to be if chained.
2884 if (NumConstIncrements > 1)
2885 --cost;
2886
2887 // Materializing increment expressions in the preheader that didn't exist in
2888 // the original code may cost a register. For example, sign-extended array
2889 // indices can produce ridiculous increments like this:
2890 // IV + ((sext i32 (2 * %s) to i64) + (-1 * (sext i32 %s to i64)))
2891 cost += NumVarIncrements;
2892
2893 // Reusing variable increments likely saves a register to hold the multiple of
2894 // the stride.
2895 cost -= NumReusedIncrements;
2896
2897 LLVM_DEBUG(dbgs() << "Chain: " << *Chain.Incs[0].UserInst << " Cost: " << costdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " Cost: " << cost << "\n"
; } } while (false)
2898 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " Cost: " << cost << "\n"
; } } while (false)
;
2899
2900 return cost < 0;
2901}
2902
2903/// Add this IV user to an existing chain or make it the head of a new chain.
2904void LSRInstance::ChainInstruction(Instruction *UserInst, Instruction *IVOper,
2905 SmallVectorImpl<ChainUsers> &ChainUsersVec) {
2906 // When IVs are used as types of varying widths, they are generally converted
2907 // to a wider type with some uses remaining narrow under a (free) trunc.
2908 Value *const NextIV = getWideOperand(IVOper);
2909 const SCEV *const OperExpr = SE.getSCEV(NextIV);
2910 const SCEV *const OperExprBase = getExprBase(OperExpr);
2911
2912 // Visit all existing chains. Check if its IVOper can be computed as a
2913 // profitable loop invariant increment from the last link in the Chain.
2914 unsigned ChainIdx = 0, NChains = IVChainVec.size();
2915 const SCEV *LastIncExpr = nullptr;
2916 for (; ChainIdx < NChains; ++ChainIdx) {
2917 IVChain &Chain = IVChainVec[ChainIdx];
2918
2919 // Prune the solution space aggressively by checking that both IV operands
2920 // are expressions that operate on the same unscaled SCEVUnknown. This
2921 // "base" will be canceled by the subsequent getMinusSCEV call. Checking
2922 // first avoids creating extra SCEV expressions.
2923 if (!StressIVChain && Chain.ExprBase != OperExprBase)
2924 continue;
2925
2926 Value *PrevIV = getWideOperand(Chain.Incs.back().IVOperand);
2927 if (!isCompatibleIVType(PrevIV, NextIV))
2928 continue;
2929
2930 // A phi node terminates a chain.
2931 if (isa<PHINode>(UserInst) && isa<PHINode>(Chain.tailUserInst()))
2932 continue;
2933
2934 // The increment must be loop-invariant so it can be kept in a register.
2935 const SCEV *PrevExpr = SE.getSCEV(PrevIV);
2936 const SCEV *IncExpr = SE.getMinusSCEV(OperExpr, PrevExpr);
2937 if (!SE.isLoopInvariant(IncExpr, L))
2938 continue;
2939
2940 if (Chain.isProfitableIncrement(OperExpr, IncExpr, SE)) {
2941 LastIncExpr = IncExpr;
2942 break;
2943 }
2944 }
2945 // If we haven't found a chain, create a new one, unless we hit the max. Don't
2946 // bother for phi nodes, because they must be last in the chain.
2947 if (ChainIdx == NChains) {
2948 if (isa<PHINode>(UserInst))
2949 return;
2950 if (NChains >= MaxChains && !StressIVChain) {
2951 LLVM_DEBUG(dbgs() << "IV Chain Limit\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain Limit\n"; } } while
(false)
;
2952 return;
2953 }
2954 LastIncExpr = OperExpr;
2955 // IVUsers may have skipped over sign/zero extensions. We don't currently
2956 // attempt to form chains involving extensions unless they can be hoisted
2957 // into this loop's AddRec.
2958 if (!isa<SCEVAddRecExpr>(LastIncExpr))
2959 return;
2960 ++NChains;
2961 IVChainVec.push_back(IVChain(IVInc(UserInst, IVOper, LastIncExpr),
2962 OperExprBase));
2963 ChainUsersVec.resize(NChains);
2964 LLVM_DEBUG(dbgs() << "IV Chain#" << ChainIdx << " Head: (" << *UserInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Head: (" << *UserInst << ") IV=" <<
*LastIncExpr << "\n"; } } while (false)
2965 << ") IV=" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Head: (" << *UserInst << ") IV=" <<
*LastIncExpr << "\n"; } } while (false)
;
2966 } else {
2967 LLVM_DEBUG(dbgs() << "IV Chain#" << ChainIdx << " Inc: (" << *UserInstdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Inc: (" << *UserInst << ") IV+" <<
*LastIncExpr << "\n"; } } while (false)
2968 << ") IV+" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Inc: (" << *UserInst << ") IV+" <<
*LastIncExpr << "\n"; } } while (false)
;
2969 // Add this IV user to the end of the chain.
2970 IVChainVec[ChainIdx].add(IVInc(UserInst, IVOper, LastIncExpr));
2971 }
2972 IVChain &Chain = IVChainVec[ChainIdx];
2973
2974 SmallPtrSet<Instruction*,4> &NearUsers = ChainUsersVec[ChainIdx].NearUsers;
2975 // This chain's NearUsers become FarUsers.
2976 if (!LastIncExpr->isZero()) {
2977 ChainUsersVec[ChainIdx].FarUsers.insert(NearUsers.begin(),
2978 NearUsers.end());
2979 NearUsers.clear();
2980 }
2981
2982 // All other uses of IVOperand become near uses of the chain.
2983 // We currently ignore intermediate values within SCEV expressions, assuming
2984 // they will eventually be used be the current chain, or can be computed
2985 // from one of the chain increments. To be more precise we could
2986 // transitively follow its user and only add leaf IV users to the set.
2987 for (User *U : IVOper->users()) {
2988 Instruction *OtherUse = dyn_cast<Instruction>(U);
2989 if (!OtherUse)
2990 continue;
2991 // Uses in the chain will no longer be uses if the chain is formed.
2992 // Include the head of the chain in this iteration (not Chain.begin()).
2993 IVChain::const_iterator IncIter = Chain.Incs.begin();
2994 IVChain::const_iterator IncEnd = Chain.Incs.end();
2995 for( ; IncIter != IncEnd; ++IncIter) {
2996 if (IncIter->UserInst == OtherUse)
2997 break;
2998 }
2999 if (IncIter != IncEnd)
3000 continue;
3001
3002 if (SE.isSCEVable(OtherUse->getType())
3003 && !isa<SCEVUnknown>(SE.getSCEV(OtherUse))
3004 && IU.isIVUserOrOperand(OtherUse)) {
3005 continue;
3006 }
3007 NearUsers.insert(OtherUse);
3008 }
3009
3010 // Since this user is part of the chain, it's no longer considered a use
3011 // of the chain.
3012 ChainUsersVec[ChainIdx].FarUsers.erase(UserInst);
3013}
3014
3015/// Populate the vector of Chains.
3016///
3017/// This decreases ILP at the architecture level. Targets with ample registers,
3018/// multiple memory ports, and no register renaming probably don't want
3019/// this. However, such targets should probably disable LSR altogether.
3020///
3021/// The job of LSR is to make a reasonable choice of induction variables across
3022/// the loop. Subsequent passes can easily "unchain" computation exposing more
3023/// ILP *within the loop* if the target wants it.
3024///
3025/// Finding the best IV chain is potentially a scheduling problem. Since LSR
3026/// will not reorder memory operations, it will recognize this as a chain, but
3027/// will generate redundant IV increments. Ideally this would be corrected later
3028/// by a smart scheduler:
3029/// = A[i]
3030/// = A[i+x]
3031/// A[i] =
3032/// A[i+x] =
3033///
3034/// TODO: Walk the entire domtree within this loop, not just the path to the
3035/// loop latch. This will discover chains on side paths, but requires
3036/// maintaining multiple copies of the Chains state.
3037void LSRInstance::CollectChains() {
3038 LLVM_DEBUG(dbgs() << "Collecting IV Chains.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Collecting IV Chains.\n";
} } while (false)
;
3039 SmallVector<ChainUsers, 8> ChainUsersVec;
3040
3041 SmallVector<BasicBlock *,8> LatchPath;
3042 BasicBlock *LoopHeader = L->getHeader();
3043 for (DomTreeNode *Rung = DT.getNode(L->getLoopLatch());
3044 Rung->getBlock() != LoopHeader; Rung = Rung->getIDom()) {
3045 LatchPath.push_back(Rung->getBlock());
3046 }
3047 LatchPath.push_back(LoopHeader);
3048
3049 // Walk the instruction stream from the loop header to the loop latch.
3050 for (BasicBlock *BB : reverse(LatchPath)) {
3051 for (Instruction &I : *BB) {
3052 // Skip instructions that weren't seen by IVUsers analysis.
3053 if (isa<PHINode>(I) || !IU.isIVUserOrOperand(&I))
3054 continue;
3055
3056 // Ignore users that are part of a SCEV expression. This way we only
3057 // consider leaf IV Users. This effectively rediscovers a portion of
3058 // IVUsers analysis but in program order this time.
3059 if (SE.isSCEVable(I.getType()) && !isa<SCEVUnknown>(SE.getSCEV(&I)))
3060 continue;
3061
3062 // Remove this instruction from any NearUsers set it may be in.
3063 for (unsigned ChainIdx = 0, NChains = IVChainVec.size();
3064 ChainIdx < NChains; ++ChainIdx) {
3065 ChainUsersVec[ChainIdx].NearUsers.erase(&I);
3066 }
3067 // Search for operands that can be chained.
3068 SmallPtrSet<Instruction*, 4> UniqueOperands;
3069 User::op_iterator IVOpEnd = I.op_end();
3070 User::op_iterator IVOpIter = findIVOperand(I.op_begin(), IVOpEnd, L, SE);
3071 while (IVOpIter != IVOpEnd) {
3072 Instruction *IVOpInst = cast<Instruction>(*IVOpIter);
3073 if (UniqueOperands.insert(IVOpInst).second)
3074 ChainInstruction(&I, IVOpInst, ChainUsersVec);
3075 IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE);
3076 }
3077 } // Continue walking down the instructions.
3078 } // Continue walking down the domtree.
3079 // Visit phi backedges to determine if the chain can generate the IV postinc.
3080 for (PHINode &PN : L->getHeader()->phis()) {
3081 if (!SE.isSCEVable(PN.getType()))
3082 continue;
3083
3084 Instruction *IncV =
3085 dyn_cast<Instruction>(PN.getIncomingValueForBlock(L->getLoopLatch()));
3086 if (IncV)
3087 ChainInstruction(&PN, IncV, ChainUsersVec);
3088 }
3089 // Remove any unprofitable chains.
3090 unsigned ChainIdx = 0;
3091 for (unsigned UsersIdx = 0, NChains = IVChainVec.size();
3092 UsersIdx < NChains; ++UsersIdx) {
3093 if (!isProfitableChain(IVChainVec[UsersIdx],
3094 ChainUsersVec[UsersIdx].FarUsers, SE))
3095 continue;
3096 // Preserve the chain at UsesIdx.
3097 if (ChainIdx != UsersIdx)
3098 IVChainVec[ChainIdx] = IVChainVec[UsersIdx];
3099 FinalizeChain(IVChainVec[ChainIdx]);
3100 ++ChainIdx;
3101 }
3102 IVChainVec.resize(ChainIdx);
3103}
3104
3105void LSRInstance::FinalizeChain(IVChain &Chain) {
3106 assert(!Chain.Incs.empty() && "empty IV chains are not allowed")((!Chain.Incs.empty() && "empty IV chains are not allowed"
) ? static_cast<void> (0) : __assert_fail ("!Chain.Incs.empty() && \"empty IV chains are not allowed\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3106, __PRETTY_FUNCTION__))
;
3107 LLVM_DEBUG(dbgs() << "Final Chain: " << *Chain.Incs[0].UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Final Chain: " << *
Chain.Incs[0].UserInst << "\n"; } } while (false)
;
3108
3109 for (const IVInc &Inc : Chain) {
3110 LLVM_DEBUG(dbgs() << " Inc: " << *Inc.UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Inc: " << *
Inc.UserInst << "\n"; } } while (false)
;
3111 auto UseI = find(Inc.UserInst->operands(), Inc.IVOperand);
3112 assert(UseI != Inc.UserInst->op_end() && "cannot find IV operand")((UseI != Inc.UserInst->op_end() && "cannot find IV operand"
) ? static_cast<void> (0) : __assert_fail ("UseI != Inc.UserInst->op_end() && \"cannot find IV operand\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3112, __PRETTY_FUNCTION__))
;
3113 IVIncSet.insert(UseI);
3114 }
3115}
3116
3117/// Return true if the IVInc can be folded into an addressing mode.
3118static bool canFoldIVIncExpr(const SCEV *IncExpr, Instruction *UserInst,
3119 Value *Operand, const TargetTransformInfo &TTI) {
3120 const SCEVConstant *IncConst = dyn_cast<SCEVConstant>(IncExpr);
3121 if (!IncConst || !isAddressUse(TTI, UserInst, Operand))
3122 return false;
3123
3124 if (IncConst->getAPInt().getMinSignedBits() > 64)
3125 return false;
3126
3127 MemAccessTy AccessTy = getAccessType(TTI, UserInst, Operand);
3128 int64_t IncOffset = IncConst->getValue()->getSExtValue();
3129 if (!isAlwaysFoldable(TTI, LSRUse::Address, AccessTy, /*BaseGV=*/nullptr,
3130 IncOffset, /*HasBaseReg=*/false))
3131 return false;
3132
3133 return true;
3134}
3135
3136/// Generate an add or subtract for each IVInc in a chain to materialize the IV
3137/// user's operand from the previous IV user's operand.
3138void LSRInstance::GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter,
3139 SmallVectorImpl<WeakTrackingVH> &DeadInsts) {
3140 // Find the new IVOperand for the head of the chain. It may have been replaced
3141 // by LSR.
3142 const IVInc &Head = Chain.Incs[0];
3143 User::op_iterator IVOpEnd = Head.UserInst->op_end();
3144 // findIVOperand returns IVOpEnd if it can no longer find a valid IV user.
3145 User::op_iterator IVOpIter = findIVOperand(Head.UserInst->op_begin(),
3146 IVOpEnd, L, SE);
3147 Value *IVSrc = nullptr;
3148 while (IVOpIter != IVOpEnd) {
3149 IVSrc = getWideOperand(*IVOpIter);
3150
3151 // If this operand computes the expression that the chain needs, we may use
3152 // it. (Check this after setting IVSrc which is used below.)
3153 //
3154 // Note that if Head.IncExpr is wider than IVSrc, then this phi is too
3155 // narrow for the chain, so we can no longer use it. We do allow using a
3156 // wider phi, assuming the LSR checked for free truncation. In that case we
3157 // should already have a truncate on this operand such that
3158 // getSCEV(IVSrc) == IncExpr.
3159 if (SE.getSCEV(*IVOpIter) == Head.IncExpr
3160 || SE.getSCEV(IVSrc) == Head.IncExpr) {
3161 break;
3162 }
3163 IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE);
3164 }
3165 if (IVOpIter == IVOpEnd) {
3166 // Gracefully give up on this chain.
3167 LLVM_DEBUG(dbgs() << "Concealed chain head: " << *Head.UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Concealed chain head: " <<
*Head.UserInst << "\n"; } } while (false)
;
3168 return;
3169 }
3170 assert(IVSrc && "Failed to find IV chain source")((IVSrc && "Failed to find IV chain source") ? static_cast
<void> (0) : __assert_fail ("IVSrc && \"Failed to find IV chain source\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3170, __PRETTY_FUNCTION__))
;
3171
3172 LLVM_DEBUG(dbgs() << "Generate chain at: " << *IVSrc << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generate chain at: " <<
*IVSrc << "\n"; } } while (false)
;
3173 Type *IVTy = IVSrc->getType();
3174 Type *IntTy = SE.getEffectiveSCEVType(IVTy);
3175 const SCEV *LeftOverExpr = nullptr;
3176 for (const IVInc &Inc : Chain) {
3177 Instruction *InsertPt = Inc.UserInst;
3178 if (isa<PHINode>(InsertPt))
3179 InsertPt = L->getLoopLatch()->getTerminator();
3180
3181 // IVOper will replace the current IV User's operand. IVSrc is the IV
3182 // value currently held in a register.
3183 Value *IVOper = IVSrc;
3184 if (!Inc.IncExpr->isZero()) {
3185 // IncExpr was the result of subtraction of two narrow values, so must
3186 // be signed.
3187 const SCEV *IncExpr = SE.getNoopOrSignExtend(Inc.IncExpr, IntTy);
3188 LeftOverExpr = LeftOverExpr ?
3189 SE.getAddExpr(LeftOverExpr, IncExpr) : IncExpr;
3190 }
3191 if (LeftOverExpr && !LeftOverExpr->isZero()) {
3192 // Expand the IV increment.
3193 Rewriter.clearPostInc();
3194 Value *IncV = Rewriter.expandCodeFor(LeftOverExpr, IntTy, InsertPt);
3195 const SCEV *IVOperExpr = SE.getAddExpr(SE.getUnknown(IVSrc),
3196 SE.getUnknown(IncV));
3197 IVOper = Rewriter.expandCodeFor(IVOperExpr, IVTy, InsertPt);
3198
3199 // If an IV increment can't be folded, use it as the next IV value.
3200 if (!canFoldIVIncExpr(LeftOverExpr, Inc.UserInst, Inc.IVOperand, TTI)) {
3201 assert(IVTy == IVOper->getType() && "inconsistent IV increment type")((IVTy == IVOper->getType() && "inconsistent IV increment type"
) ? static_cast<void> (0) : __assert_fail ("IVTy == IVOper->getType() && \"inconsistent IV increment type\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3201, __PRETTY_FUNCTION__))
;
3202 IVSrc = IVOper;
3203 LeftOverExpr = nullptr;
3204 }
3205 }
3206 Type *OperTy = Inc.IVOperand->getType();
3207 if (IVTy != OperTy) {
3208 assert(SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) &&((SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy
) && "cannot extend a chained IV") ? static_cast<void
> (0) : __assert_fail ("SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) && \"cannot extend a chained IV\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3209, __PRETTY_FUNCTION__))
3209 "cannot extend a chained IV")((SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy
) && "cannot extend a chained IV") ? static_cast<void
> (0) : __assert_fail ("SE.getTypeSizeInBits(IVTy) >= SE.getTypeSizeInBits(OperTy) && \"cannot extend a chained IV\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3209, __PRETTY_FUNCTION__))
;
3210 IRBuilder<> Builder(InsertPt);
3211 IVOper = Builder.CreateTruncOrBitCast(IVOper, OperTy, "lsr.chain");
3212 }
3213 Inc.UserInst->replaceUsesOfWith(Inc.IVOperand, IVOper);
3214 DeadInsts.emplace_back(Inc.IVOperand);
3215 }
3216 // If LSR created a new, wider phi, we may also replace its postinc. We only
3217 // do this if we also found a wide value for the head of the chain.
3218 if (isa<PHINode>(Chain.tailUserInst())) {
3219 for (PHINode &Phi : L->getHeader()->phis()) {
3220 if (!isCompatibleIVType(&Phi, IVSrc))
3221 continue;
3222 Instruction *PostIncV = dyn_cast<Instruction>(
3223 Phi.getIncomingValueForBlock(L->getLoopLatch()));
3224 if (!PostIncV || (SE.getSCEV(PostIncV) != SE.getSCEV(IVSrc)))
3225 continue;
3226 Value *IVOper = IVSrc;
3227 Type *PostIncTy = PostIncV->getType();
3228 if (IVTy != PostIncTy) {
3229 assert(PostIncTy->isPointerTy() && "mixing int/ptr IV types")((PostIncTy->isPointerTy() && "mixing int/ptr IV types"
) ? static_cast<void> (0) : __assert_fail ("PostIncTy->isPointerTy() && \"mixing int/ptr IV types\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3229, __PRETTY_FUNCTION__))
;
3230 IRBuilder<> Builder(L->getLoopLatch()->getTerminator());
3231 Builder.SetCurrentDebugLocation(PostIncV->getDebugLoc());
3232 IVOper = Builder.CreatePointerCast(IVSrc, PostIncTy, "lsr.chain");
3233 }
3234 Phi.replaceUsesOfWith(PostIncV, IVOper);
3235 DeadInsts.emplace_back(PostIncV);
3236 }
3237 }
3238}
3239
3240void LSRInstance::CollectFixupsAndInitialFormulae() {
3241 BranchInst *ExitBranch = nullptr;
3242 bool SaveCmp = TTI.canSaveCmp(L, &ExitBranch, &SE, &LI, &DT, &AC, &LibInfo);
3243
3244 for (const IVStrideUse &U : IU) {
3245 Instruction *UserInst = U.getUser();
3246 // Skip IV users that are part of profitable IV Chains.
3247 User::op_iterator UseI =
3248 find(UserInst->operands(), U.getOperandValToReplace());
3249 assert(UseI != UserInst->op_end() && "cannot find IV operand")((UseI != UserInst->op_end() && "cannot find IV operand"
) ? static_cast<void> (0) : __assert_fail ("UseI != UserInst->op_end() && \"cannot find IV operand\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3249, __PRETTY_FUNCTION__))
;
3250 if (IVIncSet.count(UseI)) {
3251 LLVM_DEBUG(dbgs() << "Use is in profitable chain: " << **UseI << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Use is in profitable chain: "
<< **UseI << '\n'; } } while (false)
;
3252 continue;
3253 }
3254
3255 LSRUse::KindType Kind = LSRUse::Basic;
3256 MemAccessTy AccessTy;
3257 if (isAddressUse(TTI, UserInst, U.getOperandValToReplace())) {
3258 Kind = LSRUse::Address;
3259 AccessTy = getAccessType(TTI, UserInst, U.getOperandValToReplace());
3260 }
3261
3262 const SCEV *S = IU.getExpr(U);
3263 PostIncLoopSet TmpPostIncLoops = U.getPostIncLoops();
3264
3265 // Equality (== and !=) ICmps are special. We can rewrite (i == N) as
3266 // (N - i == 0), and this allows (N - i) to be the expression that we work
3267 // with rather than just N or i, so we can consider the register
3268 // requirements for both N and i at the same time. Limiting this code to
3269 // equality icmps is not a problem because all interesting loops use
3270 // equality icmps, thanks to IndVarSimplify.
3271 if (ICmpInst *CI = dyn_cast<ICmpInst>(UserInst)) {
3272 // If CI can be saved in some target, like replaced inside hardware loop
3273 // in PowerPC, no need to generate initial formulae for it.
3274 if (SaveCmp && CI == dyn_cast<ICmpInst>(ExitBranch->getCondition()))
3275 continue;
3276 if (CI->isEquality()) {
3277 // Swap the operands if needed to put the OperandValToReplace on the
3278 // left, for consistency.
3279 Value *NV = CI->getOperand(1);
3280 if (NV == U.getOperandValToReplace()) {
3281 CI->setOperand(1, CI->getOperand(0));
3282 CI->setOperand(0, NV);
3283 NV = CI->getOperand(1);
3284 Changed = true;
3285 }
3286
3287 // x == y --> x - y == 0
3288 const SCEV *N = SE.getSCEV(NV);
3289 if (SE.isLoopInvariant(N, L) && isSafeToExpand(N, SE)) {
3290 // S is normalized, so normalize N before folding it into S
3291 // to keep the result normalized.
3292 N = normalizeForPostIncUse(N, TmpPostIncLoops, SE);
3293 Kind = LSRUse::ICmpZero;
3294 S = SE.getMinusSCEV(N, S);
3295 }
3296
3297 // -1 and the negations of all interesting strides (except the negation
3298 // of -1) are now also interesting.
3299 for (size_t i = 0, e = Factors.size(); i != e; ++i)
3300 if (Factors[i] != -1)
3301 Factors.insert(-(uint64_t)Factors[i]);
3302 Factors.insert(-1);
3303 }
3304 }
3305
3306 // Get or create an LSRUse.
3307 std::pair<size_t, int64_t> P = getUse(S, Kind, AccessTy);
3308 size_t LUIdx = P.first;
3309 int64_t Offset = P.second;
3310 LSRUse &LU = Uses[LUIdx];
3311
3312 // Record the fixup.
3313 LSRFixup &LF = LU.getNewFixup();
3314 LF.UserInst = UserInst;
3315 LF.OperandValToReplace = U.getOperandValToReplace();
3316 LF.PostIncLoops = TmpPostIncLoops;
3317 LF.Offset = Offset;
3318 LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L);
3319
3320 if (!LU.WidestFixupType ||
3321 SE.getTypeSizeInBits(LU.WidestFixupType) <
3322 SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))
3323 LU.WidestFixupType = LF.OperandValToReplace->getType();
3324
3325 // If this is the first use of this LSRUse, give it a formula.
3326 if (LU.Formulae.empty()) {
3327 InsertInitialFormula(S, LU, LUIdx);
3328 CountRegisters(LU.Formulae.back(), LUIdx);
3329 }
3330 }
3331
3332 LLVM_DEBUG(print_fixups(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { print_fixups(dbgs()); } } while (false)
;
3333}
3334
3335/// Insert a formula for the given expression into the given use, separating out
3336/// loop-variant portions from loop-invariant and loop-computable portions.
3337void
3338LSRInstance::InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx) {
3339 // Mark uses whose expressions cannot be expanded.
3340 if (!isSafeToExpand(S, SE))
3341 LU.RigidFormula = true;
3342
3343 Formula F;
3344 F.initialMatch(S, L, SE);
3345 bool Inserted = InsertFormula(LU, LUIdx, F);
3346 assert(Inserted && "Initial formula already exists!")((Inserted && "Initial formula already exists!") ? static_cast
<void> (0) : __assert_fail ("Inserted && \"Initial formula already exists!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3346, __PRETTY_FUNCTION__))
; (void)Inserted;
3347}
3348
3349/// Insert a simple single-register formula for the given expression into the
3350/// given use.
3351void
3352LSRInstance::InsertSupplementalFormula(const SCEV *S,
3353 LSRUse &LU, size_t LUIdx) {
3354 Formula F;
3355 F.BaseRegs.push_back(S);
3356 F.HasBaseReg = true;
3357 bool Inserted = InsertFormula(LU, LUIdx, F);
3358 assert(Inserted && "Supplemental formula already exists!")((Inserted && "Supplemental formula already exists!")
? static_cast<void> (0) : __assert_fail ("Inserted && \"Supplemental formula already exists!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3358, __PRETTY_FUNCTION__))
; (void)Inserted;
3359}
3360
3361/// Note which registers are used by the given formula, updating RegUses.
3362void LSRInstance::CountRegisters(const Formula &F, size_t LUIdx) {
3363 if (F.ScaledReg)
3364 RegUses.countRegister(F.ScaledReg, LUIdx);
3365 for (const SCEV *BaseReg : F.BaseRegs)
3366 RegUses.countRegister(BaseReg, LUIdx);
3367}
3368
3369/// If the given formula has not yet been inserted, add it to the list, and
3370/// return true. Return false otherwise.
3371bool LSRInstance::InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F) {
3372 // Do not insert formula that we will not be able to expand.
3373 assert(isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) &&((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy
, F) && "Formula is illegal") ? static_cast<void>
(0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Formula is illegal\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3374, __PRETTY_FUNCTION__))
3374 "Formula is illegal")((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy
, F) && "Formula is illegal") ? static_cast<void>
(0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Formula is illegal\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3374, __PRETTY_FUNCTION__))
;
3375
3376 if (!LU.InsertFormula(F, *L))
3377 return false;
3378
3379 CountRegisters(F, LUIdx);
3380 return true;
3381}
3382
3383/// Check for other uses of loop-invariant values which we're tracking. These
3384/// other uses will pin these values in registers, making them less profitable
3385/// for elimination.
3386/// TODO: This currently misses non-constant addrec step registers.
3387/// TODO: Should this give more weight to users inside the loop?
3388void
3389LSRInstance::CollectLoopInvariantFixupsAndFormulae() {
3390 SmallVector<const SCEV *, 8> Worklist(RegUses.begin(), RegUses.end());
3391 SmallPtrSet<const SCEV *, 32> Visited;
3392
3393 while (!Worklist.empty()) {
3394 const SCEV *S = Worklist.pop_back_val();
3395
3396 // Don't process the same SCEV twice
3397 if (!Visited.insert(S).second)
3398 continue;
3399
3400 if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S))
3401 Worklist.append(N->op_begin(), N->op_end());
3402 else if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S))
3403 Worklist.push_back(C->getOperand());
3404 else if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
3405 Worklist.push_back(D->getLHS());
3406 Worklist.push_back(D->getRHS());
3407 } else if (const SCEVUnknown *US = dyn_cast<SCEVUnknown>(S)) {
3408 const Value *V = US->getValue();
3409 if (const Instruction *Inst = dyn_cast<Instruction>(V)) {
3410 // Look for instructions defined outside the loop.
3411 if (L->contains(Inst)) continue;
3412 } else if (isa<UndefValue>(V))
3413 // Undef doesn't have a live range, so it doesn't matter.
3414 continue;
3415 for (const Use &U : V->uses()) {
3416 const Instruction *UserInst = dyn_cast<Instruction>(U.getUser());
3417 // Ignore non-instructions.
3418 if (!UserInst)
3419 continue;
3420 // Ignore instructions in other functions (as can happen with
3421 // Constants).
3422 if (UserInst->getParent()->getParent() != L->getHeader()->getParent())
3423 continue;
3424 // Ignore instructions not dominated by the loop.
3425 const BasicBlock *UseBB = !isa<PHINode>(UserInst) ?
3426 UserInst->getParent() :
3427 cast<PHINode>(UserInst)->getIncomingBlock(
3428 PHINode::getIncomingValueNumForOperand(U.getOperandNo()));
3429 if (!DT.dominates(L->getHeader(), UseBB))
3430 continue;
3431 // Don't bother if the instruction is in a BB which ends in an EHPad.
3432 if (UseBB->getTerminator()->isEHPad())
3433 continue;
3434 // Don't bother rewriting PHIs in catchswitch blocks.
3435 if (isa<CatchSwitchInst>(UserInst->getParent()->getTerminator()))
3436 continue;
3437 // Ignore uses which are part of other SCEV expressions, to avoid
3438 // analyzing them multiple times.
3439 if (SE.isSCEVable(UserInst->getType())) {
3440 const SCEV *UserS = SE.getSCEV(const_cast<Instruction *>(UserInst));
3441 // If the user is a no-op, look through to its uses.
3442 if (!isa<SCEVUnknown>(UserS))
3443 continue;
3444 if (UserS == US) {
3445 Worklist.push_back(
3446 SE.getUnknown(const_cast<Instruction *>(UserInst)));
3447 continue;
3448 }
3449 }
3450 // Ignore icmp instructions which are already being analyzed.
3451 if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UserInst)) {
3452 unsigned OtherIdx = !U.getOperandNo();
3453 Value *OtherOp = const_cast<Value *>(ICI->getOperand(OtherIdx));
3454 if (SE.hasComputableLoopEvolution(SE.getSCEV(OtherOp), L))
3455 continue;
3456 }
3457
3458 std::pair<size_t, int64_t> P = getUse(
3459 S, LSRUse::Basic, MemAccessTy());
3460 size_t LUIdx = P.first;
3461 int64_t Offset = P.second;
3462 LSRUse &LU = Uses[LUIdx];
3463 LSRFixup &LF = LU.getNewFixup();
3464 LF.UserInst = const_cast<Instruction *>(UserInst);
3465 LF.OperandValToReplace = U;
3466 LF.Offset = Offset;
3467 LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L);
3468 if (!LU.WidestFixupType ||
3469 SE.getTypeSizeInBits(LU.WidestFixupType) <
3470 SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))
3471 LU.WidestFixupType = LF.OperandValToReplace->getType();
3472 InsertSupplementalFormula(US, LU, LUIdx);
3473 CountRegisters(LU.Formulae.back(), Uses.size() - 1);
3474 break;
3475 }
3476 }
3477 }
3478}
3479
3480/// Split S into subexpressions which can be pulled out into separate
3481/// registers. If C is non-null, multiply each subexpression by C.
3482///
3483/// Return remainder expression after factoring the subexpressions captured by
3484/// Ops. If Ops is complete, return NULL.
3485static const SCEV *CollectSubexprs(const SCEV *S, const SCEVConstant *C,
3486 SmallVectorImpl<const SCEV *> &Ops,
3487 const Loop *L,
3488 ScalarEvolution &SE,
3489 unsigned Depth = 0) {
3490 // Arbitrarily cap recursion to protect compile time.
3491 if (Depth >= 3)
3492 return S;
3493
3494 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
3495 // Break out add operands.
3496 for (const SCEV *S : Add->operands()) {
3497 const SCEV *Remainder = CollectSubexprs(S, C, Ops, L, SE, Depth+1);
3498 if (Remainder)
3499 Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);
3500 }
3501 return nullptr;
3502 } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
3503 // Split a non-zero base out of an addrec.
3504 if (AR->getStart()->isZero() || !AR->isAffine())
3505 return S;
3506
3507 const SCEV *Remainder = CollectSubexprs(AR->getStart(),
3508 C, Ops, L, SE, Depth+1);
3509 // Split the non-zero AddRec unless it is part of a nested recurrence that
3510 // does not pertain to this loop.
3511 if (Remainder && (AR->getLoop() == L || !isa<SCEVAddRecExpr>(Remainder))) {
3512 Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);
3513 Remainder = nullptr;
3514 }
3515 if (Remainder != AR->getStart()) {
3516 if (!Remainder)
3517 Remainder = SE.getConstant(AR->getType(), 0);
3518 return SE.getAddRecExpr(Remainder,
3519 AR->getStepRecurrence(SE),
3520 AR->getLoop(),
3521 //FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
3522 SCEV::FlagAnyWrap);
3523 }
3524 } else if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
3525 // Break (C * (a + b + c)) into C*a + C*b + C*c.
3526 if (Mul->getNumOperands() != 2)
3527 return S;
3528 if (const SCEVConstant *Op0 =
3529 dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3530 C = C ? cast<SCEVConstant>(SE.getMulExpr(C, Op0)) : Op0;
3531 const SCEV *Remainder =
3532 CollectSubexprs(Mul->getOperand(1), C, Ops, L, SE, Depth+1);
3533 if (Remainder)
3534 Ops.push_back(SE.getMulExpr(C, Remainder));
3535 return nullptr;
3536 }
3537 }
3538 return S;
3539}
3540
3541/// Return true if the SCEV represents a value that may end up as a
3542/// post-increment operation.
3543static bool mayUsePostIncMode(const TargetTransformInfo &TTI,
3544 LSRUse &LU, const SCEV *S, const Loop *L,
3545 ScalarEvolution &SE) {
3546 if (LU.Kind != LSRUse::Address ||
3547 !LU.AccessTy.getType()->isIntOrIntVectorTy())
3548 return false;
3549 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S);
3550 if (!AR)
3551 return false;
3552 const SCEV *LoopStep = AR->getStepRecurrence(SE);
3553 if (!isa<SCEVConstant>(LoopStep))
3554 return false;
3555 if (LU.AccessTy.getType()->getScalarSizeInBits() !=
3556 LoopStep->getType()->getScalarSizeInBits())
3557 return false;
3558 // Check if a post-indexed load/store can be used.
3559 if (TTI.isIndexedLoadLegal(TTI.MIM_PostInc, AR->getType()) ||
3560 TTI.isIndexedStoreLegal(TTI.MIM_PostInc, AR->getType())) {
3561 const SCEV *LoopStart = AR->getStart();
3562 if (!isa<SCEVConstant>(LoopStart) && SE.isLoopInvariant(LoopStart, L))
3563 return true;
3564 }
3565 return false;
3566}
3567
3568/// Helper function for LSRInstance::GenerateReassociations.
3569void LSRInstance::GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,
3570 const Formula &Base,
3571 unsigned Depth, size_t Idx,
3572 bool IsScaledReg) {
3573 const SCEV *BaseReg = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];
3574 // Don't generate reassociations for the base register of a value that
3575 // may generate a post-increment operator. The reason is that the
3576 // reassociations cause extra base+register formula to be created,
3577 // and possibly chosen, but the post-increment is more efficient.
3578 if (TTI.shouldFavorPostInc() && mayUsePostIncMode(TTI, LU, BaseReg, L, SE))
3579 return;
3580 SmallVector<const SCEV *, 8> AddOps;
3581 const SCEV *Remainder = CollectSubexprs(BaseReg, nullptr, AddOps, L, SE);
3582 if (Remainder)
3583 AddOps.push_back(Remainder);
3584
3585 if (AddOps.size() == 1)
3586 return;
3587
3588 for (SmallVectorImpl<const SCEV *>::const_iterator J = AddOps.begin(),
3589 JE = AddOps.end();
3590 J != JE; ++J) {
3591 // Loop-variant "unknown" values are uninteresting; we won't be able to
3592 // do anything meaningful with them.
3593 if (isa<SCEVUnknown>(*J) && !SE.isLoopInvariant(*J, L))
3594 continue;
3595
3596 // Don't pull a constant into a register if the constant could be folded
3597 // into an immediate field.
3598 if (isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind,
3599 LU.AccessTy, *J, Base.getNumRegs() > 1))
3600 continue;
3601
3602 // Collect all operands except *J.
3603 SmallVector<const SCEV *, 8> InnerAddOps(
3604 ((const SmallVector<const SCEV *, 8> &)AddOps).begin(), J);
3605 InnerAddOps.append(std::next(J),
3606 ((const SmallVector<const SCEV *, 8> &)AddOps).end());
3607
3608 // Don't leave just a constant behind in a register if the constant could
3609 // be folded into an immediate field.
3610 if (InnerAddOps.size() == 1 &&
3611 isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind,
3612 LU.AccessTy, InnerAddOps[0], Base.getNumRegs() > 1))
3613 continue;
3614
3615 const SCEV *InnerSum = SE.getAddExpr(InnerAddOps);
3616 if (InnerSum->isZero())
3617 continue;
3618 Formula F = Base;
3619
3620 // Add the remaining pieces of the add back into the new formula.
3621 const SCEVConstant *InnerSumSC = dyn_cast<SCEVConstant>(InnerSum);
3622 if (InnerSumSC && SE.getTypeSizeInBits(InnerSumSC->getType()) <= 64 &&
3623 TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset +
3624 InnerSumSC->getValue()->getZExtValue())) {
3625 F.UnfoldedOffset =
3626 (uint64_t)F.UnfoldedOffset + InnerSumSC->getValue()->getZExtValue();
3627 if (IsScaledReg)
3628 F.ScaledReg = nullptr;
3629 else
3630 F.BaseRegs.erase(F.BaseRegs.begin() + Idx);
3631 } else if (IsScaledReg)
3632 F.ScaledReg = InnerSum;
3633 else
3634 F.BaseRegs[Idx] = InnerSum;
3635
3636 // Add J as its own register, or an unfolded immediate.
3637 const SCEVConstant *SC = dyn_cast<SCEVConstant>(*J);
3638 if (SC && SE.getTypeSizeInBits(SC->getType()) <= 64 &&
3639 TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset +
3640 SC->getValue()->getZExtValue()))
3641 F.UnfoldedOffset =
3642 (uint64_t)F.UnfoldedOffset + SC->getValue()->getZExtValue();
3643 else
3644 F.BaseRegs.push_back(*J);
3645 // We may have changed the number of register in base regs, adjust the
3646 // formula accordingly.
3647 F.canonicalize(*L);
3648
3649 if (InsertFormula(LU, LUIdx, F))
3650 // If that formula hadn't been seen before, recurse to find more like
3651 // it.
3652 // Add check on Log16(AddOps.size()) - same as Log2_32(AddOps.size()) >> 2)
3653 // Because just Depth is not enough to bound compile time.
3654 // This means that every time AddOps.size() is greater 16^x we will add
3655 // x to Depth.
3656 GenerateReassociations(LU, LUIdx, LU.Formulae.back(),
3657 Depth + 1 + (Log2_32(AddOps.size()) >> 2));
3658 }
3659}
3660
3661/// Split out subexpressions from adds and the bases of addrecs.
3662void LSRInstance::GenerateReassociations(LSRUse &LU, unsigned LUIdx,
3663 Formula Base, unsigned Depth) {
3664 assert(Base.isCanonical(*L) && "Input must be in the canonical form")((Base.isCanonical(*L) && "Input must be in the canonical form"
) ? static_cast<void> (0) : __assert_fail ("Base.isCanonical(*L) && \"Input must be in the canonical form\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3664, __PRETTY_FUNCTION__))
;
3665 // Arbitrarily cap recursion to protect compile time.
3666 if (Depth >= 3)
3667 return;
3668
3669 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
3670 GenerateReassociationsImpl(LU, LUIdx, Base, Depth, i);
3671
3672 if (Base.Scale == 1)
3673 GenerateReassociationsImpl(LU, LUIdx, Base, Depth,
3674 /* Idx */ -1, /* IsScaledReg */ true);
3675}
3676
3677/// Generate a formula consisting of all of the loop-dominating registers added
3678/// into a single register.
3679void LSRInstance::GenerateCombinations(LSRUse &LU, unsigned LUIdx,
3680 Formula Base) {
3681 // This method is only interesting on a plurality of registers.
3682 if (Base.BaseRegs.size() + (Base.Scale == 1) +
3683 (Base.UnfoldedOffset != 0) <= 1)
3684 return;
3685
3686 // Flatten the representation, i.e., reg1 + 1*reg2 => reg1 + reg2, before
3687 // processing the formula.
3688 Base.unscale();
3689 SmallVector<const SCEV *, 4> Ops;
3690 Formula NewBase = Base;
3691 NewBase.BaseRegs.clear();
3692 Type *CombinedIntegerType = nullptr;
3693 for (const SCEV *BaseReg : Base.BaseRegs) {
3694 if (SE.properlyDominates(BaseReg, L->getHeader()) &&
3695 !SE.hasComputableLoopEvolution(BaseReg, L)) {
3696 if (!CombinedIntegerType)
3697 CombinedIntegerType = SE.getEffectiveSCEVType(BaseReg->getType());
3698 Ops.push_back(BaseReg);
3699 }
3700 else
3701 NewBase.BaseRegs.push_back(BaseReg);
3702 }
3703
3704 // If no register is relevant, we're done.
3705 if (Ops.size() == 0)
3706 return;
3707
3708 // Utility function for generating the required variants of the combined
3709 // registers.
3710 auto GenerateFormula = [&](const SCEV *Sum) {
3711 Formula F = NewBase;
3712
3713 // TODO: If Sum is zero, it probably means ScalarEvolution missed an
3714 // opportunity to fold something. For now, just ignore such cases
3715 // rather than proceed with zero in a register.
3716 if (Sum->isZero())
3717 return;
3718
3719 F.BaseRegs.push_back(Sum);
3720 F.canonicalize(*L);
3721 (void)InsertFormula(LU, LUIdx, F);
3722 };
3723
3724 // If we collected at least two registers, generate a formula combining them.
3725 if (Ops.size() > 1) {
3726 SmallVector<const SCEV *, 4> OpsCopy(Ops); // Don't let SE modify Ops.
3727 GenerateFormula(SE.getAddExpr(OpsCopy));
3728 }
3729
3730 // If we have an unfolded offset, generate a formula combining it with the
3731 // registers collected.
3732 if (NewBase.UnfoldedOffset) {
3733 assert(CombinedIntegerType && "Missing a type for the unfolded offset")((CombinedIntegerType && "Missing a type for the unfolded offset"
) ? static_cast<void> (0) : __assert_fail ("CombinedIntegerType && \"Missing a type for the unfolded offset\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3733, __PRETTY_FUNCTION__))
;
3734 Ops.push_back(SE.getConstant(CombinedIntegerType, NewBase.UnfoldedOffset,
3735 true));
3736 NewBase.UnfoldedOffset = 0;
3737 GenerateFormula(SE.getAddExpr(Ops));
3738 }
3739}
3740
3741/// Helper function for LSRInstance::GenerateSymbolicOffsets.
3742void LSRInstance::GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx,
3743 const Formula &Base, size_t Idx,
3744 bool IsScaledReg) {
3745 const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];
3746 GlobalValue *GV = ExtractSymbol(G, SE);
3747 if (G->isZero() || !GV)
3748 return;
3749 Formula F = Base;
3750 F.BaseGV = GV;
3751 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))
3752 return;
3753 if (IsScaledReg)
3754 F.ScaledReg = G;
3755 else
3756 F.BaseRegs[Idx] = G;
3757 (void)InsertFormula(LU, LUIdx, F);
3758}
3759
3760/// Generate reuse formulae using symbolic offsets.
3761void LSRInstance::GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx,
3762 Formula Base) {
3763 // We can't add a symbolic offset if the address already contains one.
3764 if (Base.BaseGV) return;
3765
3766 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
3767 GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, i);
3768 if (Base.Scale == 1)
3769 GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, /* Idx */ -1,
3770 /* IsScaledReg */ true);
3771}
3772
3773/// Helper function for LSRInstance::GenerateConstantOffsets.
3774void LSRInstance::GenerateConstantOffsetsImpl(
3775 LSRUse &LU, unsigned LUIdx, const Formula &Base,
3776 const SmallVectorImpl<int64_t> &Worklist, size_t Idx, bool IsScaledReg) {
3777
3778 auto GenerateOffset = [&](const SCEV *G, int64_t Offset) {
3779 Formula F = Base;
3780 F.BaseOffset = (uint64_t)Base.BaseOffset - Offset;
3781
3782 if (isLegalUse(TTI, LU.MinOffset - Offset, LU.MaxOffset - Offset, LU.Kind,
3783 LU.AccessTy, F)) {
3784 // Add the offset to the base register.
3785 const SCEV *NewG = SE.getAddExpr(SE.getConstant(G->getType(), Offset), G);
3786 // If it cancelled out, drop the base register, otherwise update it.
3787 if (NewG->isZero()) {
3788 if (IsScaledReg) {
3789 F.Scale = 0;
3790 F.ScaledReg = nullptr;
3791 } else
3792 F.deleteBaseReg(F.BaseRegs[Idx]);
3793 F.canonicalize(*L);
3794 } else if (IsScaledReg)
3795 F.ScaledReg = NewG;
3796 else
3797 F.BaseRegs[Idx] = NewG;
3798
3799 (void)InsertFormula(LU, LUIdx, F);
3800 }
3801 };
3802
3803 const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];
3804
3805 // With constant offsets and constant steps, we can generate pre-inc
3806 // accesses by having the offset equal the step. So, for access #0 with a
3807 // step of 8, we generate a G - 8 base which would require the first access
3808 // to be ((G - 8) + 8),+,8. The pre-indexed access then updates the pointer
3809 // for itself and hopefully becomes the base for other accesses. This means
3810 // means that a single pre-indexed access can be generated to become the new
3811 // base pointer for each iteration of the loop, resulting in no extra add/sub
3812 // instructions for pointer updating.
3813 if (FavorBackedgeIndex && LU.Kind == LSRUse::Address) {
3814 if (auto *GAR = dyn_cast<SCEVAddRecExpr>(G)) {
3815 if (auto *StepRec =
3816 dyn_cast<SCEVConstant>(GAR->getStepRecurrence(SE))) {
3817 const APInt &StepInt = StepRec->getAPInt();
3818 int64_t Step = StepInt.isNegative() ?
3819 StepInt.getSExtValue() : StepInt.getZExtValue();
3820
3821 for (int64_t Offset : Worklist) {
3822 Offset -= Step;
3823 GenerateOffset(G, Offset);
3824 }
3825 }
3826 }
3827 }
3828 for (int64_t Offset : Worklist)
3829 GenerateOffset(G, Offset);
3830
3831 int64_t Imm = ExtractImmediate(G, SE);
3832 if (G->isZero() || Imm == 0)
3833 return;
3834 Formula F = Base;
3835 F.BaseOffset = (uint64_t)F.BaseOffset + Imm;
3836 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))
3837 return;
3838 if (IsScaledReg)
3839 F.ScaledReg = G;
3840 else
3841 F.BaseRegs[Idx] = G;
3842 (void)InsertFormula(LU, LUIdx, F);
3843}
3844
3845/// GenerateConstantOffsets - Generate reuse formulae using symbolic offsets.
3846void LSRInstance::GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx,
3847 Formula Base) {
3848 // TODO: For now, just add the min and max offset, because it usually isn't
3849 // worthwhile looking at everything inbetween.
3850 SmallVector<int64_t, 2> Worklist;
3851 Worklist.push_back(LU.MinOffset);
3852 if (LU.MaxOffset != LU.MinOffset)
3853 Worklist.push_back(LU.MaxOffset);
3854
3855 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
3856 GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, i);
3857 if (Base.Scale == 1)
3858 GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, /* Idx */ -1,
3859 /* IsScaledReg */ true);
3860}
3861
3862/// For ICmpZero, check to see if we can scale up the comparison. For example, x
3863/// == y -> x*c == y*c.
3864void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx,
3865 Formula Base) {
3866 if (LU.Kind != LSRUse::ICmpZero) return;
3867
3868 // Determine the integer type for the base formula.
3869 Type *IntTy = Base.getType();
3870 if (!IntTy) return;
3871 if (SE.getTypeSizeInBits(IntTy) > 64) return;
3872
3873 // Don't do this if there is more than one offset.
3874 if (LU.MinOffset != LU.MaxOffset) return;
3875
3876 // Check if transformation is valid. It is illegal to multiply pointer.
3877 if (Base.ScaledReg && Base.ScaledReg->getType()->isPointerTy())
3878 return;
3879 for (const SCEV *BaseReg : Base.BaseRegs)
3880 if (BaseReg->getType()->isPointerTy())
3881 return;
3882 assert(!Base.BaseGV && "ICmpZero use is not legal!")((!Base.BaseGV && "ICmpZero use is not legal!") ? static_cast
<void> (0) : __assert_fail ("!Base.BaseGV && \"ICmpZero use is not legal!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3882, __PRETTY_FUNCTION__))
;
3883
3884 // Check each interesting stride.
3885 for (int64_t Factor : Factors) {
3886 // Check that the multiplication doesn't overflow.
3887 if (Base.BaseOffset == std::numeric_limits<int64_t>::min() && Factor == -1)
3888 continue;
3889 int64_t NewBaseOffset = (uint64_t)Base.BaseOffset * Factor;
3890 if (NewBaseOffset / Factor != Base.BaseOffset)
3891 continue;
3892 // If the offset will be truncated at this use, check that it is in bounds.
3893 if (!IntTy->isPointerTy() &&
3894 !ConstantInt::isValueValidForType(IntTy, NewBaseOffset))
3895 continue;
3896
3897 // Check that multiplying with the use offset doesn't overflow.
3898 int64_t Offset = LU.MinOffset;
3899 if (Offset == std::numeric_limits<int64_t>::min() && Factor == -1)
3900 continue;
3901 Offset = (uint64_t)Offset * Factor;
3902 if (Offset / Factor != LU.MinOffset)
3903 continue;
3904 // If the offset will be truncated at this use, check that it is in bounds.
3905 if (!IntTy->isPointerTy() &&
3906 !ConstantInt::isValueValidForType(IntTy, Offset))
3907 continue;
3908
3909 Formula F = Base;
3910 F.BaseOffset = NewBaseOffset;
3911
3912 // Check that this scale is legal.
3913 if (!isLegalUse(TTI, Offset, Offset, LU.Kind, LU.AccessTy, F))
3914 continue;
3915
3916 // Compensate for the use having MinOffset built into it.
3917 F.BaseOffset = (uint64_t)F.BaseOffset + Offset - LU.MinOffset;
3918
3919 const SCEV *FactorS = SE.getConstant(IntTy, Factor);
3920
3921 // Check that multiplying with each base register doesn't overflow.
3922 for (size_t i = 0, e = F.BaseRegs.size(); i != e; ++i) {
3923 F.BaseRegs[i] = SE.getMulExpr(F.BaseRegs[i], FactorS);
3924 if (getExactSDiv(F.BaseRegs[i], FactorS, SE) != Base.BaseRegs[i])
3925 goto next;
3926 }
3927
3928 // Check that multiplying with the scaled register doesn't overflow.
3929 if (F.ScaledReg) {
3930 F.ScaledReg = SE.getMulExpr(F.ScaledReg, FactorS);
3931 if (getExactSDiv(F.ScaledReg, FactorS, SE) != Base.ScaledReg)
3932 continue;
3933 }
3934
3935 // Check that multiplying with the unfolded offset doesn't overflow.
3936 if (F.UnfoldedOffset != 0) {
3937 if (F.UnfoldedOffset == std::numeric_limits<int64_t>::min() &&
3938 Factor == -1)
3939 continue;
3940 F.UnfoldedOffset = (uint64_t)F.UnfoldedOffset * Factor;
3941 if (F.UnfoldedOffset / Factor != Base.UnfoldedOffset)
3942 continue;
3943 // If the offset will be truncated, check that it is in bounds.
3944 if (!IntTy->isPointerTy() &&
3945 !ConstantInt::isValueValidForType(IntTy, F.UnfoldedOffset))
3946 continue;
3947 }
3948
3949 // If we make it here and it's legal, add it.
3950 (void)InsertFormula(LU, LUIdx, F);
3951 next:;
3952 }
3953}
3954
3955/// Generate stride factor reuse formulae by making use of scaled-offset address
3956/// modes, for example.
3957void LSRInstance::GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base) {
3958 // Determine the integer type for the base formula.
3959 Type *IntTy = Base.getType();
3960 if (!IntTy) return;
3961
3962 // If this Formula already has a scaled register, we can't add another one.
3963 // Try to unscale the formula to generate a better scale.
3964 if (Base.Scale != 0 && !Base.unscale())
3965 return;
3966
3967 assert(Base.Scale == 0 && "unscale did not did its job!")((Base.Scale == 0 && "unscale did not did its job!") ?
static_cast<void> (0) : __assert_fail ("Base.Scale == 0 && \"unscale did not did its job!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3967, __PRETTY_FUNCTION__))
;
3968
3969 // Check each interesting stride.
3970 for (int64_t Factor : Factors) {
3971 Base.Scale = Factor;
3972 Base.HasBaseReg = Base.BaseRegs.size() > 1;
3973 // Check whether this scale is going to be legal.
3974 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,
3975 Base)) {
3976 // As a special-case, handle special out-of-loop Basic users specially.
3977 // TODO: Reconsider this special case.
3978 if (LU.Kind == LSRUse::Basic &&
3979 isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LSRUse::Special,
3980 LU.AccessTy, Base) &&
3981 LU.AllFixupsOutsideLoop)
3982 LU.Kind = LSRUse::Special;
3983 else
3984 continue;
3985 }
3986 // For an ICmpZero, negating a solitary base register won't lead to
3987 // new solutions.
3988 if (LU.Kind == LSRUse::ICmpZero &&
3989 !Base.HasBaseReg && Base.BaseOffset == 0 && !Base.BaseGV)
3990 continue;
3991 // For each addrec base reg, if its loop is current loop, apply the scale.
3992 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) {
3993 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Base.BaseRegs[i]);
3994 if (AR && (AR->getLoop() == L || LU.AllFixupsOutsideLoop)) {
3995 const SCEV *FactorS = SE.getConstant(IntTy, Factor);
3996 if (FactorS->isZero())
3997 continue;
3998 // Divide out the factor, ignoring high bits, since we'll be
3999 // scaling the value back up in the end.
4000 if (const SCEV *Quotient = getExactSDiv(AR, FactorS, SE, true)) {
4001 // TODO: This could be optimized to avoid all the copying.
4002 Formula F = Base;
4003 F.ScaledReg = Quotient;
4004 F.deleteBaseReg(F.BaseRegs[i]);
4005 // The canonical representation of 1*reg is reg, which is already in
4006 // Base. In that case, do not try to insert the formula, it will be
4007 // rejected anyway.
4008 if (F.Scale == 1 && (F.BaseRegs.empty() ||
4009 (AR->getLoop() != L && LU.AllFixupsOutsideLoop)))
4010 continue;
4011 // If AllFixupsOutsideLoop is true and F.Scale is 1, we may generate
4012 // non canonical Formula with ScaledReg's loop not being L.
4013 if (F.Scale == 1 && LU.AllFixupsOutsideLoop)
4014 F.canonicalize(*L);
4015 (void)InsertFormula(LU, LUIdx, F);
4016 }
4017 }
4018 }
4019 }
4020}
4021
4022/// Generate reuse formulae from different IV types.
4023void LSRInstance::GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base) {
4024 // Don't bother truncating symbolic values.
4025 if (Base.BaseGV) return;
4026
4027 // Determine the integer type for the base formula.
4028 Type *DstTy = Base.getType();
4029 if (!DstTy) return;
4030 DstTy = SE.getEffectiveSCEVType(DstTy);
4031
4032 for (Type *SrcTy : Types) {
4033 if (SrcTy != DstTy && TTI.isTruncateFree(SrcTy, DstTy)) {
4034 Formula F = Base;
4035
4036 // Sometimes SCEV is able to prove zero during ext transform. It may
4037 // happen if SCEV did not do all possible transforms while creating the
4038 // initial node (maybe due to depth limitations), but it can do them while
4039 // taking ext.
4040 if (F.ScaledReg) {
4041 const SCEV *NewScaledReg = SE.getAnyExtendExpr(F.ScaledReg, SrcTy);
4042 if (NewScaledReg->isZero())
4043 continue;
4044 F.ScaledReg = NewScaledReg;
4045 }
4046 bool HasZeroBaseReg = false;
4047 for (const SCEV *&BaseReg : F.BaseRegs) {
4048 const SCEV *NewBaseReg = SE.getAnyExtendExpr(BaseReg, SrcTy);
4049 if (NewBaseReg->isZero()) {
4050 HasZeroBaseReg = true;
4051 break;
4052 }
4053 BaseReg = NewBaseReg;
4054 }
4055 if (HasZeroBaseReg)
4056 continue;
4057
4058 // TODO: This assumes we've done basic processing on all uses and
4059 // have an idea what the register usage is.
4060 if (!F.hasRegsUsedByUsesOtherThan(LUIdx, RegUses))
4061 continue;
4062
4063 F.canonicalize(*L);
4064 (void)InsertFormula(LU, LUIdx, F);
4065 }
4066 }
4067}
4068
4069namespace {
4070
4071/// Helper class for GenerateCrossUseConstantOffsets. It's used to defer
4072/// modifications so that the search phase doesn't have to worry about the data
4073/// structures moving underneath it.
4074struct WorkItem {
4075 size_t LUIdx;
4076 int64_t Imm;
4077 const SCEV *OrigReg;
4078
4079 WorkItem(size_t LI, int64_t I, const SCEV *R)
4080 : LUIdx(LI), Imm(I), OrigReg(R) {}
4081
4082 void print(raw_ostream &OS) const;
4083 void dump() const;
4084};
4085
4086} // end anonymous namespace
4087
4088#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
4089void WorkItem::print(raw_ostream &OS) const {
4090 OS << "in formulae referencing " << *OrigReg << " in use " << LUIdx
4091 << " , add offset " << Imm;
4092}
4093
4094LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void WorkItem::dump() const {
4095 print(errs()); errs() << '\n';
4096}
4097#endif
4098
4099/// Look for registers which are a constant distance apart and try to form reuse
4100/// opportunities between them.
4101void LSRInstance::GenerateCrossUseConstantOffsets() {
4102 // Group the registers by their value without any added constant offset.
4103 using ImmMapTy = std::map<int64_t, const SCEV *>;
4104
4105 DenseMap<const SCEV *, ImmMapTy> Map;
4106 DenseMap<const SCEV *, SmallBitVector> UsedByIndicesMap;
4107 SmallVector<const SCEV *, 8> Sequence;
4108 for (const SCEV *Use : RegUses) {
4109 const SCEV *Reg = Use; // Make a copy for ExtractImmediate to modify.
4110 int64_t Imm = ExtractImmediate(Reg, SE);
4111 auto Pair = Map.insert(std::make_pair(Reg, ImmMapTy()));
4112 if (Pair.second)
4113 Sequence.push_back(Reg);
4114 Pair.first->second.insert(std::make_pair(Imm, Use));
4115 UsedByIndicesMap[Reg] |= RegUses.getUsedByIndices(Use);
4116 }
4117
4118 // Now examine each set of registers with the same base value. Build up
4119 // a list of work to do and do the work in a separate step so that we're
4120 // not adding formulae and register counts while we're searching.
4121 SmallVector<WorkItem, 32> WorkItems;
4122 SmallSet<std::pair<size_t, int64_t>, 32> UniqueItems;
4123 for (const SCEV *Reg : Sequence) {
4124 const ImmMapTy &Imms = Map.find(Reg)->second;
4125
4126 // It's not worthwhile looking for reuse if there's only one offset.
4127 if (Imms.size() == 1)
4128 continue;
4129
4130 LLVM_DEBUG(dbgs() << "Generating cross-use offsets for " << *Reg << ':';do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (const auto &Entry : Imms
) dbgs() << ' ' << Entry.first; dbgs() << '\n'
; } } while (false)
4131 for (const auto &Entrydo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (const auto &Entry : Imms
) dbgs() << ' ' << Entry.first; dbgs() << '\n'
; } } while (false)
4132 : Imms) dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (const auto &Entry : Imms
) dbgs() << ' ' << Entry.first; dbgs() << '\n'
; } } while (false)
4133 << ' ' << Entry.first;do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (const auto &Entry : Imms
) dbgs() << ' ' << Entry.first; dbgs() << '\n'
; } } while (false)
4134 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generating cross-use offsets for "
<< *Reg << ':'; for (const auto &Entry : Imms
) dbgs() << ' ' << Entry.first; dbgs() << '\n'
; } } while (false)
;
4135
4136 // Examine each offset.
4137 for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end();
4138 J != JE; ++J) {
4139 const SCEV *OrigReg = J->second;
4140
4141 int64_t JImm = J->first;
4142 const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(OrigReg);
4143
4144 if (!isa<SCEVConstant>(OrigReg) &&
4145 UsedByIndicesMap[Reg].count() == 1) {
4146 LLVM_DEBUG(dbgs() << "Skipping cross-use reuse for " << *OrigRegdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Skipping cross-use reuse for "
<< *OrigReg << '\n'; } } while (false)
4147 << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Skipping cross-use reuse for "
<< *OrigReg << '\n'; } } while (false)
;
4148 continue;
4149 }
4150
4151 // Conservatively examine offsets between this orig reg a few selected
4152 // other orig regs.
4153 int64_t First = Imms.begin()->first;
4154 int64_t Last = std::prev(Imms.end())->first;
4155 // Compute (First + Last) / 2 without overflow using the fact that
4156 // First + Last = 2 * (First + Last) + (First ^ Last).
4157 int64_t Avg = (First & Last) + ((First ^ Last) >> 1);
4158 // If the result is negative and First is odd and Last even (or vice versa),
4159 // we rounded towards -inf. Add 1 in that case, to round towards 0.
4160 Avg = Avg + ((First ^ Last) & ((uint64_t)Avg >> 63));
4161 ImmMapTy::const_iterator OtherImms[] = {
4162 Imms.begin(), std::prev(Imms.end()),
4163 Imms.lower_bound(Avg)};
4164 for (size_t i = 0, e = array_lengthof(OtherImms); i != e; ++i) {
4165 ImmMapTy::const_iterator M = OtherImms[i];
4166 if (M == J || M == JE) continue;
4167
4168 // Compute the difference between the two.
4169 int64_t Imm = (uint64_t)JImm - M->first;
4170 for (unsigned LUIdx : UsedByIndices.set_bits())
4171 // Make a memo of this use, offset, and register tuple.
4172 if (UniqueItems.insert(std::make_pair(LUIdx, Imm)).second)
4173 WorkItems.push_back(WorkItem(LUIdx, Imm, OrigReg));
4174 }
4175 }
4176 }
4177
4178 Map.clear();
4179 Sequence.clear();
4180 UsedByIndicesMap.clear();
4181 UniqueItems.clear();
4182
4183 // Now iterate through the worklist and add new formulae.
4184 for (const WorkItem &WI : WorkItems) {
4185 size_t LUIdx = WI.LUIdx;
4186 LSRUse &LU = Uses[LUIdx];
4187 int64_t Imm = WI.Imm;
4188 const SCEV *OrigReg = WI.OrigReg;
4189
4190 Type *IntTy = SE.getEffectiveSCEVType(OrigReg->getType());
4191 const SCEV *NegImmS = SE.getSCEV(ConstantInt::get(IntTy, -(uint64_t)Imm));
4192 unsigned BitWidth = SE.getTypeSizeInBits(IntTy);
4193
4194 // TODO: Use a more targeted data structure.
4195 for (size_t L = 0, LE = LU.Formulae.size(); L != LE; ++L) {
4196 Formula F = LU.Formulae[L];
4197 // FIXME: The code for the scaled and unscaled registers looks
4198 // very similar but slightly different. Investigate if they
4199 // could be merged. That way, we would not have to unscale the
4200 // Formula.
4201 F.unscale();
4202 // Use the immediate in the scaled register.
4203 if (F.ScaledReg == OrigReg) {
4204 int64_t Offset = (uint64_t)F.BaseOffset + Imm * (uint64_t)F.Scale;
4205 // Don't create 50 + reg(-50).
4206 if (F.referencesReg(SE.getSCEV(
4207 ConstantInt::get(IntTy, -(uint64_t)Offset))))
4208 continue;
4209 Formula NewF = F;
4210 NewF.BaseOffset = Offset;
4211 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,
4212 NewF))
4213 continue;
4214 NewF.ScaledReg = SE.getAddExpr(NegImmS, NewF.ScaledReg);
4215
4216 // If the new scale is a constant in a register, and adding the constant
4217 // value to the immediate would produce a value closer to zero than the
4218 // immediate itself, then the formula isn't worthwhile.
4219 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewF.ScaledReg))
4220 if (C->getValue()->isNegative() != (NewF.BaseOffset < 0) &&
4221 (C->getAPInt().abs() * APInt(BitWidth, F.Scale))
4222 .ule(std::abs(NewF.BaseOffset)))
4223 continue;
4224
4225 // OK, looks good.
4226 NewF.canonicalize(*this->L);
4227 (void)InsertFormula(LU, LUIdx, NewF);
4228 } else {
4229 // Use the immediate in a base register.
4230 for (size_t N = 0, NE = F.BaseRegs.size(); N != NE; ++N) {
4231 const SCEV *BaseReg = F.BaseRegs[N];
4232 if (BaseReg != OrigReg)
4233 continue;
4234 Formula NewF = F;
4235 NewF.BaseOffset = (uint64_t)NewF.BaseOffset + Imm;
4236 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset,
4237 LU.Kind, LU.AccessTy, NewF)) {
4238 if (TTI.shouldFavorPostInc() &&
4239 mayUsePostIncMode(TTI, LU, OrigReg, this->L, SE))
4240 continue;
4241 if (!TTI.isLegalAddImmediate((uint64_t)NewF.UnfoldedOffset + Imm))
4242 continue;
4243 NewF = F;
4244 NewF.UnfoldedOffset = (uint64_t)NewF.UnfoldedOffset + Imm;
4245 }
4246 NewF.BaseRegs[N] = SE.getAddExpr(NegImmS, BaseReg);
4247
4248 // If the new formula has a constant in a register, and adding the
4249 // constant value to the immediate would produce a value closer to
4250 // zero than the immediate itself, then the formula isn't worthwhile.
4251 for (const SCEV *NewReg : NewF.BaseRegs)
4252 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewReg))
4253 if ((C->getAPInt() + NewF.BaseOffset)
4254 .abs()
4255 .slt(std::abs(NewF.BaseOffset)) &&
4256 (C->getAPInt() + NewF.BaseOffset).countTrailingZeros() >=
4257 countTrailingZeros<uint64_t>(NewF.BaseOffset))
4258 goto skip_formula;
4259
4260 // Ok, looks good.
4261 NewF.canonicalize(*this->L);
4262 (void)InsertFormula(LU, LUIdx, NewF);
4263 break;
4264 skip_formula:;
4265 }
4266 }
4267 }
4268 }
4269}
4270
4271/// Generate formulae for each use.
4272void
4273LSRInstance::GenerateAllReuseFormulae() {
4274 // This is split into multiple loops so that hasRegsUsedByUsesOtherThan
4275 // queries are more precise.
4276 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4277 LSRUse &LU = Uses[LUIdx];
4278 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4279 GenerateReassociations(LU, LUIdx, LU.Formulae[i]);
4280 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4281 GenerateCombinations(LU, LUIdx, LU.Formulae[i]);
4282 }
4283 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4284 LSRUse &LU = Uses[LUIdx];
4285 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4286 GenerateSymbolicOffsets(LU, LUIdx, LU.Formulae[i]);
4287 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4288 GenerateConstantOffsets(LU, LUIdx, LU.Formulae[i]);
4289 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4290 GenerateICmpZeroScales(LU, LUIdx, LU.Formulae[i]);
4291 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4292 GenerateScales(LU, LUIdx, LU.Formulae[i]);
4293 }
4294 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4295 LSRUse &LU = Uses[LUIdx];
4296 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4297 GenerateTruncates(LU, LUIdx, LU.Formulae[i]);
4298 }
4299
4300 GenerateCrossUseConstantOffsets();
4301
4302 LLVM_DEBUG(dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (false)
4303 "After generating reuse formulae:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (false)
4304 print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (false)
;
4305}
4306
4307/// If there are multiple formulae with the same set of registers used
4308/// by other uses, pick the best one and delete the others.
4309void LSRInstance::FilterOutUndesirableDedicatedRegisters() {
4310 DenseSet<const SCEV *> VisitedRegs;
4311 SmallPtrSet<const SCEV *, 16> Regs;
4312 SmallPtrSet<const SCEV *, 16> LoserRegs;
4313#ifndef NDEBUG
4314 bool ChangedFormulae = false;
4315#endif
4316
4317 // Collect the best formula for each unique set of shared registers. This
4318 // is reset for each use.
4319 using BestFormulaeTy =
4320 DenseMap<SmallVector<const SCEV *, 4>, size_t, UniquifierDenseMapInfo>;
4321
4322 BestFormulaeTy BestFormulae;
4323
4324 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4325 LSRUse &LU = Uses[LUIdx];
4326 LLVM_DEBUG(dbgs() << "Filtering for use "; LU.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Filtering for use "; LU.print
(dbgs()); dbgs() << '\n'; } } while (false)
4327 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Filtering for use "; LU.print
(dbgs()); dbgs() << '\n'; } } while (false)
;
4328
4329 bool Any = false;
4330 for (size_t FIdx = 0, NumForms = LU.Formulae.size();
4331 FIdx != NumForms; ++FIdx) {
4332 Formula &F = LU.Formulae[FIdx];
4333
4334 // Some formulas are instant losers. For example, they may depend on
4335 // nonexistent AddRecs from other loops. These need to be filtered
4336 // immediately, otherwise heuristics could choose them over others leading
4337 // to an unsatisfactory solution. Passing LoserRegs into RateFormula here
4338 // avoids the need to recompute this information across formulae using the
4339 // same bad AddRec. Passing LoserRegs is also essential unless we remove
4340 // the corresponding bad register from the Regs set.
4341 Cost CostF(L, SE, TTI);
4342 Regs.clear();
4343 CostF.RateFormula(F, Regs, VisitedRegs, LU, &LoserRegs);
4344 if (CostF.isLoser()) {
4345 // During initial formula generation, undesirable formulae are generated
4346 // by uses within other loops that have some non-trivial address mode or
4347 // use the postinc form of the IV. LSR needs to provide these formulae
4348 // as the basis of rediscovering the desired formula that uses an AddRec
4349 // corresponding to the existing phi. Once all formulae have been
4350 // generated, these initial losers may be pruned.
4351 LLVM_DEBUG(dbgs() << " Filtering loser "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering loser "; F.print
(dbgs()); dbgs() << "\n"; } } while (false)
4352 dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering loser "; F.print
(dbgs()); dbgs() << "\n"; } } while (false)
;
4353 }
4354 else {
4355 SmallVector<const SCEV *, 4> Key;
4356 for (const SCEV *Reg : F.BaseRegs) {
4357 if (RegUses.isRegUsedByUsesOtherThan(Reg, LUIdx))
4358 Key.push_back(Reg);
4359 }
4360 if (F.ScaledReg &&
4361 RegUses.isRegUsedByUsesOtherThan(F.ScaledReg, LUIdx))
4362 Key.push_back(F.ScaledReg);
4363 // Unstable sort by host order ok, because this is only used for
4364 // uniquifying.
4365 llvm::sort(Key);
4366
4367 std::pair<BestFormulaeTy::const_iterator, bool> P =
4368 BestFormulae.insert(std::make_pair(Key, FIdx));
4369 if (P.second)
4370 continue;
4371
4372 Formula &Best = LU.Formulae[P.first->second];
4373
4374 Cost CostBest(L, SE, TTI);
4375 Regs.clear();
4376 CostBest.RateFormula(Best, Regs, VisitedRegs, LU);
4377 if (CostF.isLess(CostBest))
4378 std::swap(F, Best);
4379 LLVM_DEBUG(dbgs() << " Filtering out formula "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (false)
4380 dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (false)
4381 " in favor of formula ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (false)
4382 Best.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (false)
;
4383 }
4384#ifndef NDEBUG
4385 ChangedFormulae = true;
4386#endif
4387 LU.DeleteFormula(F);
4388 --FIdx;
4389 --NumForms;
4390 Any = true;
4391 }
4392
4393 // Now that we've filtered out some formulae, recompute the Regs set.
4394 if (Any)
4395 LU.RecomputeRegs(LUIdx, RegUses);
4396
4397 // Reset this to prepare for the next use.
4398 BestFormulae.clear();
4399 }
4400
4401 LLVM_DEBUG(if (ChangedFormulae) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
4402 dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
4403 "After filtering out undesirable candidates:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
4404 print_uses(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
4405 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
;
4406}
4407
4408/// Estimate the worst-case number of solutions the solver might have to
4409/// consider. It almost never considers this many solutions because it prune the
4410/// search space, but the pruning isn't always sufficient.
4411size_t LSRInstance::EstimateSearchSpaceComplexity() const {
4412 size_t Power = 1;
4413 for (const LSRUse &LU : Uses) {
4414 size_t FSize = LU.Formulae.size();
4415 if (FSize >= ComplexityLimit) {
4416 Power = ComplexityLimit;
4417 break;
4418 }
4419 Power *= FSize;
4420 if (Power >= ComplexityLimit)
4421 break;
4422 }
4423 return Power;
4424}
4425
4426/// When one formula uses a superset of the registers of another formula, it
4427/// won't help reduce register pressure (though it may not necessarily hurt
4428/// register pressure); remove it to simplify the system.
4429void LSRInstance::NarrowSearchSpaceByDetectingSupersets() {
4430 if (EstimateSearchSpaceComplexity() >= ComplexityLimit) {
4431 LLVM_DEBUG(dbgs() << "The search space is too complex.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
; } } while (false)
;
4432
4433 LLVM_DEBUG(dbgs() << "Narrowing the search space by eliminating formulae "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by eliminating formulae "
"which use a superset of registers used by other " "formulae.\n"
; } } while (false)
4434 "which use a superset of registers used by other "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by eliminating formulae "
"which use a superset of registers used by other " "formulae.\n"
; } } while (false)
4435 "formulae.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by eliminating formulae "
"which use a superset of registers used by other " "formulae.\n"
; } } while (false)
;
4436
4437 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4438 LSRUse &LU = Uses[LUIdx];
4439 bool Any = false;
4440 for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {
4441 Formula &F = LU.Formulae[i];
4442 // Look for a formula with a constant or GV in a register. If the use
4443 // also has a formula with that same value in an immediate field,
4444 // delete the one that uses a register.
4445 for (SmallVectorImpl<const SCEV *>::const_iterator
4446 I = F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I) {
4447 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(*I)) {
4448 Formula NewF = F;
4449 //FIXME: Formulas should store bitwidth to do wrapping properly.
4450 // See PR41034.
4451 NewF.BaseOffset += (uint64_t)C->getValue()->getSExtValue();
4452 NewF.BaseRegs.erase(NewF.BaseRegs.begin() +
4453 (I - F.BaseRegs.begin()));
4454 if (LU.HasFormulaWithSameRegs(NewF)) {
4455 LLVM_DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (false)
4456 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (false)
;
4457 LU.DeleteFormula(F);
4458 --i;
4459 --e;
4460 Any = true;
4461 break;
4462 }
4463 } else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(*I)) {
4464 if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue()))
4465 if (!F.BaseGV) {
4466 Formula NewF = F;
4467 NewF.BaseGV = GV;
4468 NewF.BaseRegs.erase(NewF.BaseRegs.begin() +
4469 (I - F.BaseRegs.begin()));
4470 if (LU.HasFormulaWithSameRegs(NewF)) {
4471 LLVM_DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (false)
4472 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (false)
;
4473 LU.DeleteFormula(F);
4474 --i;
4475 --e;
4476 Any = true;
4477 break;
4478 }
4479 }
4480 }
4481 }
4482 }
4483 if (Any)
4484 LU.RecomputeRegs(LUIdx, RegUses);
4485 }
4486
4487 LLVM_DEBUG(dbgs() << "After pre-selection:\n"; print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (false)
;
4488 }
4489}
4490
4491/// When there are many registers for expressions like A, A+1, A+2, etc.,
4492/// allocate a single register for them.
4493void LSRInstance::NarrowSearchSpaceByCollapsingUnrolledCode() {
4494 if (EstimateSearchSpaceComplexity() < ComplexityLimit)
4495 return;
4496
4497 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by assuming that uses separated "
"by a constant offset will use the same registers.\n"; } } while
(false)
4498 dbgs() << "The search space is too complex.\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by assuming that uses separated "
"by a constant offset will use the same registers.\n"; } } while
(false)
4499 "Narrowing the search space by assuming that uses separated "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by assuming that uses separated "
"by a constant offset will use the same registers.\n"; } } while
(false)
4500 "by a constant offset will use the same registers.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by assuming that uses separated "
"by a constant offset will use the same registers.\n"; } } while
(false)
;
4501
4502 // This is especially useful for unrolled loops.
4503
4504 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4505 LSRUse &LU = Uses[LUIdx];
4506 for (const Formula &F : LU.Formulae) {
4507 if (F.BaseOffset == 0 || (F.Scale != 0 && F.Scale != 1))
4508 continue;
4509
4510 LSRUse *LUThatHas = FindUseWithSimilarFormula(F, LU);
4511 if (!LUThatHas)
4512 continue;
4513
4514 if (!reconcileNewOffset(*LUThatHas, F.BaseOffset, /*HasBaseReg=*/ false,
4515 LU.Kind, LU.AccessTy))
4516 continue;
4517
4518 LLVM_DEBUG(dbgs() << " Deleting use "; LU.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting use "; LU.print
(dbgs()); dbgs() << '\n'; } } while (false)
;
4519
4520 LUThatHas->AllFixupsOutsideLoop &= LU.AllFixupsOutsideLoop;
4521
4522 // Transfer the fixups of LU to LUThatHas.
4523 for (LSRFixup &Fixup : LU.Fixups) {
4524 Fixup.Offset += F.BaseOffset;
4525 LUThatHas->pushFixup(Fixup);
4526 LLVM_DEBUG(dbgs() << "New fixup has offset " << Fixup.Offset << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New fixup has offset " <<
Fixup.Offset << '\n'; } } while (false)
;
4527 }
4528
4529 // Delete formulae from the new use which are no longer legal.
4530 bool Any = false;
4531 for (size_t i = 0, e = LUThatHas->Formulae.size(); i != e; ++i) {
4532 Formula &F = LUThatHas->Formulae[i];
4533 if (!isLegalUse(TTI, LUThatHas->MinOffset, LUThatHas->MaxOffset,
4534 LUThatHas->Kind, LUThatHas->AccessTy, F)) {
4535 LLVM_DEBUG(dbgs() << " Deleting "; F.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (false)
;
4536 LUThatHas->DeleteFormula(F);
4537 --i;
4538 --e;
4539 Any = true;
4540 }
4541 }
4542
4543 if (Any)
4544 LUThatHas->RecomputeRegs(LUThatHas - &Uses.front(), RegUses);
4545
4546 // Delete the old use.
4547 DeleteUse(LU, LUIdx);
4548 --LUIdx;
4549 --NumUses;
4550 break;
4551 }
4552 }
4553
4554 LLVM_DEBUG(dbgs() << "After pre-selection:\n"; print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (false)
;
4555}
4556
4557/// Call FilterOutUndesirableDedicatedRegisters again, if necessary, now that
4558/// we've done more filtering, as it may be able to find more formulae to
4559/// eliminate.
4560void LSRInstance::NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(){
4561 if (EstimateSearchSpaceComplexity() >= ComplexityLimit) {
4562 LLVM_DEBUG(dbgs() << "The search space is too complex.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
; } } while (false)
;
4563
4564 LLVM_DEBUG(dbgs() << "Narrowing the search space by re-filtering out "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by re-filtering out "
"undesirable dedicated registers.\n"; } } while (false)
4565 "undesirable dedicated registers.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by re-filtering out "
"undesirable dedicated registers.\n"; } } while (false)
;
4566
4567 FilterOutUndesirableDedicatedRegisters();
4568
4569 LLVM_DEBUG(dbgs() << "After pre-selection:\n"; print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (false)
;
4570 }
4571}
4572
4573/// If a LSRUse has multiple formulae with the same ScaledReg and Scale.
4574/// Pick the best one and delete the others.
4575/// This narrowing heuristic is to keep as many formulae with different
4576/// Scale and ScaledReg pair as possible while narrowing the search space.
4577/// The benefit is that it is more likely to find out a better solution
4578/// from a formulae set with more Scale and ScaledReg variations than
4579/// a formulae set with the same Scale and ScaledReg. The picking winner
4580/// reg heuristic will often keep the formulae with the same Scale and
4581/// ScaledReg and filter others, and we want to avoid that if possible.
4582void LSRInstance::NarrowSearchSpaceByFilterFormulaWithSameScaledReg() {
4583 if (EstimateSearchSpaceComplexity() < ComplexityLimit)
4584 return;
4585
4586 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by choosing the best Formula " "from the Formulae with the same Scale and ScaledReg.\n"
; } } while (false)
4587 dbgs() << "The search space is too complex.\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by choosing the best Formula " "from the Formulae with the same Scale and ScaledReg.\n"
; } } while (false)
4588 "Narrowing the search space by choosing the best Formula "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by choosing the best Formula " "from the Formulae with the same Scale and ScaledReg.\n"
; } } while (false)
4589 "from the Formulae with the same Scale and ScaledReg.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by choosing the best Formula " "from the Formulae with the same Scale and ScaledReg.\n"
; } } while (false)
;
4590
4591 // Map the "Scale * ScaledReg" pair to the best formula of current LSRUse.
4592 using BestFormulaeTy = DenseMap<std::pair<const SCEV *, int64_t>, size_t>;
4593
4594 BestFormulaeTy BestFormulae;
4595#ifndef NDEBUG
4596 bool ChangedFormulae = false;
4597#endif
4598 DenseSet<const SCEV *> VisitedRegs;
4599 SmallPtrSet<const SCEV *, 16> Regs;
4600
4601 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4602 LSRUse &LU = Uses[LUIdx];
4603 LLVM_DEBUG(dbgs() << "Filtering for use "; LU.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Filtering for use "; LU.print
(dbgs()); dbgs() << '\n'; } } while (false)
4604 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Filtering for use "; LU.print
(dbgs()); dbgs() << '\n'; } } while (false)
;
4605
4606 // Return true if Formula FA is better than Formula FB.
4607 auto IsBetterThan = [&](Formula &FA, Formula &FB) {
4608 // First we will try to choose the Formula with fewer new registers.
4609 // For a register used by current Formula, the more the register is
4610 // shared among LSRUses, the less we increase the register number
4611 // counter of the formula.
4612 size_t FARegNum = 0;
4613 for (const SCEV *Reg : FA.BaseRegs) {
4614 const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(Reg);
4615 FARegNum += (NumUses - UsedByIndices.count() + 1);
4616 }
4617 size_t FBRegNum = 0;
4618 for (const SCEV *Reg : FB.BaseRegs) {
4619 const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(Reg);
4620 FBRegNum += (NumUses - UsedByIndices.count() + 1);
4621 }
4622 if (FARegNum != FBRegNum)
4623 return FARegNum < FBRegNum;
4624
4625 // If the new register numbers are the same, choose the Formula with
4626 // less Cost.
4627 Cost CostFA(L, SE, TTI);
4628 Cost CostFB(L, SE, TTI);
4629 Regs.clear();
4630 CostFA.RateFormula(FA, Regs, VisitedRegs, LU);
4631 Regs.clear();
4632 CostFB.RateFormula(FB, Regs, VisitedRegs, LU);
4633 return CostFA.isLess(CostFB);
4634 };
4635
4636 bool Any = false;
4637 for (size_t FIdx = 0, NumForms = LU.Formulae.size(); FIdx != NumForms;
4638 ++FIdx) {
4639 Formula &F = LU.Formulae[FIdx];
4640 if (!F.ScaledReg)
4641 continue;
4642 auto P = BestFormulae.insert({{F.ScaledReg, F.Scale}, FIdx});
4643 if (P.second)
4644 continue;
4645
4646 Formula &Best = LU.Formulae[P.first->second];
4647 if (IsBetterThan(F, Best))
4648 std::swap(F, Best);
4649 LLVM_DEBUG(dbgs() << " Filtering out formula "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (false)
4650 dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (false)
4651 " in favor of formula ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (false)
4652 Best.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n" " in favor of formula "
; Best.print(dbgs()); dbgs() << '\n'; } } while (false)
;
4653#ifndef NDEBUG
4654 ChangedFormulae = true;
4655#endif
4656 LU.DeleteFormula(F);
4657 --FIdx;
4658 --NumForms;
4659 Any = true;
4660 }
4661 if (Any)
4662 LU.RecomputeRegs(LUIdx, RegUses);
4663
4664 // Reset this to prepare for the next use.
4665 BestFormulae.clear();
4666 }
4667
4668 LLVM_DEBUG(if (ChangedFormulae) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
4669 dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
4670 "After filtering out undesirable candidates:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
4671 print_uses(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
4672 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
;
4673}
4674
4675/// The function delete formulas with high registers number expectation.
4676/// Assuming we don't know the value of each formula (already delete
4677/// all inefficient), generate probability of not selecting for each
4678/// register.
4679/// For example,
4680/// Use1:
4681/// reg(a) + reg({0,+,1})
4682/// reg(a) + reg({-1,+,1}) + 1
4683/// reg({a,+,1})
4684/// Use2:
4685/// reg(b) + reg({0,+,1})
4686/// reg(b) + reg({-1,+,1}) + 1
4687/// reg({b,+,1})
4688/// Use3:
4689/// reg(c) + reg(b) + reg({0,+,1})
4690/// reg(c) + reg({b,+,1})
4691///
4692/// Probability of not selecting
4693/// Use1 Use2 Use3
4694/// reg(a) (1/3) * 1 * 1
4695/// reg(b) 1 * (1/3) * (1/2)
4696/// reg({0,+,1}) (2/3) * (2/3) * (1/2)
4697/// reg({-1,+,1}) (2/3) * (2/3) * 1
4698/// reg({a,+,1}) (2/3) * 1 * 1
4699/// reg({b,+,1}) 1 * (2/3) * (2/3)
4700/// reg(c) 1 * 1 * 0
4701///
4702/// Now count registers number mathematical expectation for each formula:
4703/// Note that for each use we exclude probability if not selecting for the use.
4704/// For example for Use1 probability for reg(a) would be just 1 * 1 (excluding
4705/// probabilty 1/3 of not selecting for Use1).
4706/// Use1:
4707/// reg(a) + reg({0,+,1}) 1 + 1/3 -- to be deleted
4708/// reg(a) + reg({-1,+,1}) + 1 1 + 4/9 -- to be deleted
4709/// reg({a,+,1}) 1
4710/// Use2:
4711/// reg(b) + reg({0,+,1}) 1/2 + 1/3 -- to be deleted
4712/// reg(b) + reg({-1,+,1}) + 1 1/2 + 2/3 -- to be deleted
4713/// reg({b,+,1}) 2/3
4714/// Use3:
4715/// reg(c) + reg(b) + reg({0,+,1}) 1 + 1/3 + 4/9 -- to be deleted
4716/// reg(c) + reg({b,+,1}) 1 + 2/3
4717void LSRInstance::NarrowSearchSpaceByDeletingCostlyFormulas() {
4718 if (EstimateSearchSpaceComplexity() < ComplexityLimit)
4719 return;
4720 // Ok, we have too many of formulae on our hands to conveniently handle.
4721 // Use a rough heuristic to thin out the list.
4722
4723 // Set of Regs wich will be 100% used in final solution.
4724 // Used in each formula of a solution (in example above this is reg(c)).
4725 // We can skip them in calculations.
4726 SmallPtrSet<const SCEV *, 4> UniqRegs;
4727 LLVM_DEBUG(dbgs() << "The search space is too complex.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
; } } while (false)
;
4728
4729 // Map each register to probability of not selecting
4730 DenseMap <const SCEV *, float> RegNumMap;
4731 for (const SCEV *Reg : RegUses) {
4732 if (UniqRegs.count(Reg))
4733 continue;
4734 float PNotSel = 1;
4735 for (const LSRUse &LU : Uses) {
4736 if (!LU.Regs.count(Reg))
4737 continue;
4738 float P = LU.getNotSelectedProbability(Reg);
4739 if (P != 0.0)
4740 PNotSel *= P;
4741 else
4742 UniqRegs.insert(Reg);
4743 }
4744 RegNumMap.insert(std::make_pair(Reg, PNotSel));
4745 }
4746
4747 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by deleting costly formulas\n"
; } } while (false)
4748 dbgs() << "Narrowing the search space by deleting costly formulas\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by deleting costly formulas\n"
; } } while (false)
;
4749
4750 // Delete formulas where registers number expectation is high.
4751 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4752 LSRUse &LU = Uses[LUIdx];
4753 // If nothing to delete - continue.
4754 if (LU.Formulae.size() < 2)
4755 continue;
4756 // This is temporary solution to test performance. Float should be
4757 // replaced with round independent type (based on integers) to avoid
4758 // different results for different target builds.
4759 float FMinRegNum = LU.Formulae[0].getNumRegs();
4760 float FMinARegNum = LU.Formulae[0].getNumRegs();
4761 size_t MinIdx = 0;
4762 for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {
4763 Formula &F = LU.Formulae[i];
4764 float FRegNum = 0;
4765 float FARegNum = 0;
4766 for (const SCEV *BaseReg : F.BaseRegs) {
4767 if (UniqRegs.count(BaseReg))
4768 continue;
4769 FRegNum += RegNumMap[BaseReg] / LU.getNotSelectedProbability(BaseReg);
4770 if (isa<SCEVAddRecExpr>(BaseReg))
4771 FARegNum +=
4772 RegNumMap[BaseReg] / LU.getNotSelectedProbability(BaseReg);
4773 }
4774 if (const SCEV *ScaledReg = F.ScaledReg) {
4775 if (!UniqRegs.count(ScaledReg)) {
4776 FRegNum +=
4777 RegNumMap[ScaledReg] / LU.getNotSelectedProbability(ScaledReg);
4778 if (isa<SCEVAddRecExpr>(ScaledReg))
4779 FARegNum +=
4780 RegNumMap[ScaledReg] / LU.getNotSelectedProbability(ScaledReg);
4781 }
4782 }
4783 if (FMinRegNum > FRegNum ||
4784 (FMinRegNum == FRegNum && FMinARegNum > FARegNum)) {
4785 FMinRegNum = FRegNum;
4786 FMinARegNum = FARegNum;
4787 MinIdx = i;
4788 }
4789 }
4790 LLVM_DEBUG(dbgs() << " The formula "; LU.Formulae[MinIdx].print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " The formula "; LU.Formulae
[MinIdx].print(dbgs()); dbgs() << " with min reg num " <<
FMinRegNum << '\n'; } } while (false)
4791 dbgs() << " with min reg num " << FMinRegNum << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " The formula "; LU.Formulae
[MinIdx].print(dbgs()); dbgs() << " with min reg num " <<
FMinRegNum << '\n'; } } while (false)
;
4792 if (MinIdx != 0)
4793 std::swap(LU.Formulae[MinIdx], LU.Formulae[0]);
4794 while (LU.Formulae.size() != 1) {
4795 LLVM_DEBUG(dbgs() << " Deleting "; LU.Formulae.back().print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; LU.Formulae
.back().print(dbgs()); dbgs() << '\n'; } } while (false
)
4796 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; LU.Formulae
.back().print(dbgs()); dbgs() << '\n'; } } while (false
)
;
4797 LU.Formulae.pop_back();
4798 }
4799 LU.RecomputeRegs(LUIdx, RegUses);
4800 assert(LU.Formulae.size() == 1 && "Should be exactly 1 min regs formula")((LU.Formulae.size() == 1 && "Should be exactly 1 min regs formula"
) ? static_cast<void> (0) : __assert_fail ("LU.Formulae.size() == 1 && \"Should be exactly 1 min regs formula\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4800, __PRETTY_FUNCTION__))
;
4801 Formula &F = LU.Formulae[0];
4802 LLVM_DEBUG(dbgs() << " Leaving only "; F.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Leaving only "; F.print
(dbgs()); dbgs() << '\n'; } } while (false)
;
4803 // When we choose the formula, the regs become unique.
4804 UniqRegs.insert(F.BaseRegs.begin(), F.BaseRegs.end());
4805 if (F.ScaledReg)
4806 UniqRegs.insert(F.ScaledReg);
4807 }
4808 LLVM_DEBUG(dbgs() << "After pre-selection:\n"; print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (false)
;
4809}
4810
4811/// Pick a register which seems likely to be profitable, and then in any use
4812/// which has any reference to that register, delete all formulae which do not
4813/// reference that register.
4814void LSRInstance::NarrowSearchSpaceByPickingWinnerRegs() {
4815 // With all other options exhausted, loop until the system is simple
4816 // enough to handle.
4817 SmallPtrSet<const SCEV *, 4> Taken;
4818 while (EstimateSearchSpaceComplexity() >= ComplexityLimit) {
4819 // Ok, we have too many of formulae on our hands to conveniently handle.
4820 // Use a rough heuristic to thin out the list.
4821 LLVM_DEBUG(dbgs() << "The search space is too complex.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
; } } while (false)
;
4822
4823 // Pick the register which is used by the most LSRUses, which is likely
4824 // to be a good reuse register candidate.
4825 const SCEV *Best = nullptr;
4826 unsigned BestNum = 0;
4827 for (const SCEV *Reg : RegUses) {
4828 if (Taken.count(Reg))
4829 continue;
4830 if (!Best) {
4831 Best = Reg;
4832 BestNum = RegUses.getUsedByIndices(Reg).count();
4833 } else {
4834 unsigned Count = RegUses.getUsedByIndices(Reg).count();
4835 if (Count > BestNum) {
4836 Best = Reg;
4837 BestNum = Count;
4838 }
4839 }
4840 }
4841 assert(Best && "Failed to find best LSRUse candidate")((Best && "Failed to find best LSRUse candidate") ? static_cast
<void> (0) : __assert_fail ("Best && \"Failed to find best LSRUse candidate\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4841, __PRETTY_FUNCTION__))
;
4842
4843 LLVM_DEBUG(dbgs() << "Narrowing the search space by assuming " << *Bestdo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by assuming "
<< *Best << " will yield profitable reuse.\n"; }
} while (false)
4844 << " will yield profitable reuse.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by assuming "
<< *Best << " will yield profitable reuse.\n"; }
} while (false)
;
4845 Taken.insert(Best);
4846
4847 // In any use with formulae which references this register, delete formulae
4848 // which don't reference it.
4849 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4850 LSRUse &LU = Uses[LUIdx];
4851 if (!LU.Regs.count(Best)) continue;
4852
4853 bool Any = false;
4854 for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {
4855 Formula &F = LU.Formulae[i];
4856 if (!F.referencesReg(Best)) {
4857 LLVM_DEBUG(dbgs() << " Deleting "; F.print(dbgs()); dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (false)
;
4858 LU.DeleteFormula(F);
4859 --e;
4860 --i;
4861 Any = true;
4862 assert(e != 0 && "Use has no formulae left! Is Regs inconsistent?")((e != 0 && "Use has no formulae left! Is Regs inconsistent?"
) ? static_cast<void> (0) : __assert_fail ("e != 0 && \"Use has no formulae left! Is Regs inconsistent?\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4862, __PRETTY_FUNCTION__))
;
4863 continue;
4864 }
4865 }
4866
4867 if (Any)
4868 LU.RecomputeRegs(LUIdx, RegUses);
4869 }
4870
4871 LLVM_DEBUG(dbgs() << "After pre-selection:\n"; print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "After pre-selection:\n"; print_uses
(dbgs()); } } while (false)
;
4872 }
4873}
4874
4875/// If there are an extraordinary number of formulae to choose from, use some
4876/// rough heuristics to prune down the number of formulae. This keeps the main
4877/// solver from taking an extraordinary amount of time in some worst-case
4878/// scenarios.
4879void LSRInstance::NarrowSearchSpaceUsingHeuristics() {
4880 NarrowSearchSpaceByDetectingSupersets();
4881 NarrowSearchSpaceByCollapsingUnrolledCode();
4882 NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters();
4883 if (FilterSameScaledReg)
4884 NarrowSearchSpaceByFilterFormulaWithSameScaledReg();
4885 if (LSRExpNarrow)
4886 NarrowSearchSpaceByDeletingCostlyFormulas();
4887 else
4888 NarrowSearchSpaceByPickingWinnerRegs();
4889}
4890
4891/// This is the recursive solver.
4892void LSRInstance::SolveRecurse(SmallVectorImpl<const Formula *> &Solution,
4893 Cost &SolutionCost,
4894 SmallVectorImpl<const Formula *> &Workspace,
4895 const Cost &CurCost,
4896 const SmallPtrSet<const SCEV *, 16> &CurRegs,
4897 DenseSet<const SCEV *> &VisitedRegs) const {
4898 // Some ideas:
4899 // - prune more:
4900 // - use more aggressive filtering
4901 // - sort the formula so that the most profitable solutions are found first
4902 // - sort the uses too
4903 // - search faster:
4904 // - don't compute a cost, and then compare. compare while computing a cost
4905 // and bail early.
4906 // - track register sets with SmallBitVector
4907
4908 const LSRUse &LU = Uses[Workspace.size()];
4909
4910 // If this use references any register that's already a part of the
4911 // in-progress solution, consider it a requirement that a formula must
4912 // reference that register in order to be considered. This prunes out
4913 // unprofitable searching.
4914 SmallSetVector<const SCEV *, 4> ReqRegs;
4915 for (const SCEV *S : CurRegs)
4916 if (LU.Regs.count(S))
4917 ReqRegs.insert(S);
4918
4919 SmallPtrSet<const SCEV *, 16> NewRegs;
4920 Cost NewCost(L, SE, TTI);
4921 for (const Formula &F : LU.Formulae) {
4922 // Ignore formulae which may not be ideal in terms of register reuse of
4923 // ReqRegs. The formula should use all required registers before
4924 // introducing new ones.
4925 int NumReqRegsToFind = std::min(F.getNumRegs(), ReqRegs.size());
4926 for (const SCEV *Reg : ReqRegs) {
4927 if ((F.ScaledReg && F.ScaledReg == Reg) ||
4928 is_contained(F.BaseRegs, Reg)) {
4929 --NumReqRegsToFind;
4930 if (NumReqRegsToFind == 0)
4931 break;
4932 }
4933 }
4934 if (NumReqRegsToFind != 0) {
4935 // If none of the formulae satisfied the required registers, then we could
4936 // clear ReqRegs and try again. Currently, we simply give up in this case.
4937 continue;
4938 }
4939
4940 // Evaluate the cost of the current formula. If it's already worse than
4941 // the current best, prune the search at that point.
4942 NewCost = CurCost;
4943 NewRegs = CurRegs;
4944 NewCost.RateFormula(F, NewRegs, VisitedRegs, LU);
4945 if (NewCost.isLess(SolutionCost)) {
4946 Workspace.push_back(&F);
4947 if (Workspace.size() != Uses.size()) {
4948 SolveRecurse(Solution, SolutionCost, Workspace, NewCost,
4949 NewRegs, VisitedRegs);
4950 if (F.getNumRegs() == 1 && Workspace.size() == 1)
4951 VisitedRegs.insert(F.ScaledReg ? F.ScaledReg : F.BaseRegs[0]);
4952 } else {
4953 LLVM_DEBUG(dbgs() << "New best at "; NewCost.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New best at "; NewCost.print
(dbgs()); dbgs() << ".\nRegs:\n"; for (const SCEV *S : NewRegs
) dbgs() << "- " << *S << "\n"; dbgs() <<
'\n'; } } while (false)
4954 dbgs() << ".\nRegs:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New best at "; NewCost.print
(dbgs()); dbgs() << ".\nRegs:\n"; for (const SCEV *S : NewRegs
) dbgs() << "- " << *S << "\n"; dbgs() <<
'\n'; } } while (false)
4955 for (const SCEV *S : NewRegs) dbgs()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New best at "; NewCost.print
(dbgs()); dbgs() << ".\nRegs:\n"; for (const SCEV *S : NewRegs
) dbgs() << "- " << *S << "\n"; dbgs() <<
'\n'; } } while (false)
4956 << "- " << *S << "\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New best at "; NewCost.print
(dbgs()); dbgs() << ".\nRegs:\n"; for (const SCEV *S : NewRegs
) dbgs() << "- " << *S << "\n"; dbgs() <<
'\n'; } } while (false)
4957 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "New best at "; NewCost.print
(dbgs()); dbgs() << ".\nRegs:\n"; for (const SCEV *S : NewRegs
) dbgs() << "- " << *S << "\n"; dbgs() <<
'\n'; } } while (false)
;
4958
4959 SolutionCost = NewCost;
4960 Solution = Workspace;
4961 }
4962 Workspace.pop_back();
4963 }
4964 }
4965}
4966
4967/// Choose one formula from each use. Return the results in the given Solution
4968/// vector.
4969void LSRInstance::Solve(SmallVectorImpl<const Formula *> &Solution) const {
4970 SmallVector<const Formula *, 8> Workspace;
4971 Cost SolutionCost(L, SE, TTI);
4972 SolutionCost.Lose();
4973 Cost CurCost(L, SE, TTI);
4974 SmallPtrSet<const SCEV *, 16> CurRegs;
4975 DenseSet<const SCEV *> VisitedRegs;
4976 Workspace.reserve(Uses.size());
4977
4978 // SolveRecurse does all the work.
4979 SolveRecurse(Solution, SolutionCost, Workspace, CurCost,
4980 CurRegs, VisitedRegs);
4981 if (Solution.empty()) {
4982 LLVM_DEBUG(dbgs() << "\nNo Satisfactory Solution\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nNo Satisfactory Solution\n"
; } } while (false)
;
4983 return;
4984 }
4985
4986 // Ok, we've now made all our decisions.
4987 LLVM_DEBUG(dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
4988 "The chosen solution requires ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
4989 SolutionCost.print(dbgs()); dbgs() << ":\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
4990 for (size_t i = 0, e = Uses.size(); i != e; ++i) {do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
4991 dbgs() << " ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
4992 Uses[i].print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
4993 dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
4994 " ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
4995 Solution[i]->print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
4996 dbgs() << '\n';do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
4997 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "The chosen solution requires "
; SolutionCost.print(dbgs()); dbgs() << ":\n"; for (size_t
i = 0, e = Uses.size(); i != e; ++i) { dbgs() << " ";
Uses[i].print(dbgs()); dbgs() << "\n" " "; Solution
[i]->print(dbgs()); dbgs() << '\n'; }; } } while (false
)
;
4998
4999 assert(Solution.size() == Uses.size() && "Malformed solution!")((Solution.size() == Uses.size() && "Malformed solution!"
) ? static_cast<void> (0) : __assert_fail ("Solution.size() == Uses.size() && \"Malformed solution!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4999, __PRETTY_FUNCTION__))
;
5000}
5001
5002/// Helper for AdjustInsertPositionForExpand. Climb up the dominator tree far as
5003/// we can go while still being dominated by the input positions. This helps
5004/// canonicalize the insert position, which encourages sharing.
5005BasicBlock::iterator
5006LSRInstance::HoistInsertPosition(BasicBlock::iterator IP,
5007 const SmallVectorImpl<Instruction *> &Inputs)
5008 const {
5009 Instruction *Tentative = &*IP;
5010 while (true) {
5011 bool AllDominate = true;
5012 Instruction *BetterPos = nullptr;
5013 // Don't bother attempting to insert before a catchswitch, their basic block
5014 // cannot have other non-PHI instructions.
5015 if (isa<CatchSwitchInst>(Tentative))
5016 return IP;
5017
5018 for (Instruction *Inst : Inputs) {
5019 if (Inst == Tentative || !DT.dominates(Inst, Tentative)) {
5020 AllDominate = false;
5021 break;
5022 }
5023 // Attempt to find an insert position in the middle of the block,
5024 // instead of at the end, so that it can be used for other expansions.
5025 if (Tentative->getParent() == Inst->getParent() &&
5026 (!BetterPos || !DT.dominates(Inst, BetterPos)))
5027 BetterPos = &*std::next(BasicBlock::iterator(Inst));
5028 }
5029 if (!AllDominate)
5030 break;
5031 if (BetterPos)
5032 IP = BetterPos->getIterator();
5033 else
5034 IP = Tentative->getIterator();
5035
5036 const Loop *IPLoop = LI.getLoopFor(IP->getParent());
5037 unsigned IPLoopDepth = IPLoop ? IPLoop->getLoopDepth() : 0;
5038
5039 BasicBlock *IDom;
5040 for (DomTreeNode *Rung = DT.getNode(IP->getParent()); ; ) {
5041 if (!Rung) return IP;
5042 Rung = Rung->getIDom();
5043 if (!Rung) return IP;
5044 IDom = Rung->getBlock();
5045
5046 // Don't climb into a loop though.
5047 const Loop *IDomLoop = LI.getLoopFor(IDom);
5048 unsigned IDomDepth = IDomLoop ? IDomLoop->getLoopDepth() : 0;
5049 if (IDomDepth <= IPLoopDepth &&
5050 (IDomDepth != IPLoopDepth || IDomLoop == IPLoop))
5051 break;
5052 }
5053
5054 Tentative = IDom->getTerminator();
5055 }
5056
5057 return IP;
5058}
5059
5060/// Determine an input position which will be dominated by the operands and
5061/// which will dominate the result.
5062BasicBlock::iterator
5063LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator LowestIP,
5064 const LSRFixup &LF,
5065 const LSRUse &LU,
5066 SCEVExpander &Rewriter) const {
5067 // Collect some instructions which must be dominated by the
5068 // expanding replacement. These must be dominated by any operands that
5069 // will be required in the expansion.
5070 SmallVector<Instruction *, 4> Inputs;
5071 if (Instruction *I = dyn_cast<Instruction>(LF.OperandValToReplace))
5072 Inputs.push_back(I);
5073 if (LU.Kind == LSRUse::ICmpZero)
5074 if (Instruction *I =
5075 dyn_cast<Instruction>(cast<ICmpInst>(LF.UserInst)->getOperand(1)))
5076 Inputs.push_back(I);
5077 if (LF.PostIncLoops.count(L)) {
5078 if (LF.isUseFullyOutsideLoop(L))
5079 Inputs.push_back(L->getLoopLatch()->getTerminator());
5080 else
5081 Inputs.push_back(IVIncInsertPos);
5082 }
5083 // The expansion must also be dominated by the increment positions of any
5084 // loops it for which it is using post-inc mode.
5085 for (const Loop *PIL : LF.PostIncLoops) {
5086 if (PIL == L) continue;
5087
5088 // Be dominated by the loop exit.
5089 SmallVector<BasicBlock *, 4> ExitingBlocks;
5090 PIL->getExitingBlocks(ExitingBlocks);
5091 if (!ExitingBlocks.empty()) {
5092 BasicBlock *BB = ExitingBlocks[0];
5093 for (unsigned i = 1, e = ExitingBlocks.size(); i != e; ++i)
5094 BB = DT.findNearestCommonDominator(BB, ExitingBlocks[i]);
5095 Inputs.push_back(BB->getTerminator());
5096 }
5097 }
5098
5099 assert(!isa<PHINode>(LowestIP) && !LowestIP->isEHPad()((!isa<PHINode>(LowestIP) && !LowestIP->isEHPad
() && !isa<DbgInfoIntrinsic>(LowestIP) &&
"Insertion point must be a normal instruction") ? static_cast
<void> (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5101, __PRETTY_FUNCTION__))
5100 && !isa<DbgInfoIntrinsic>(LowestIP) &&((!isa<PHINode>(LowestIP) && !LowestIP->isEHPad
() && !isa<DbgInfoIntrinsic>(LowestIP) &&
"Insertion point must be a normal instruction") ? static_cast
<void> (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5101, __PRETTY_FUNCTION__))
5101 "Insertion point must be a normal instruction")((!isa<PHINode>(LowestIP) && !LowestIP->isEHPad
() && !isa<DbgInfoIntrinsic>(LowestIP) &&
"Insertion point must be a normal instruction") ? static_cast
<void> (0) : __assert_fail ("!isa<PHINode>(LowestIP) && !LowestIP->isEHPad() && !isa<DbgInfoIntrinsic>(LowestIP) && \"Insertion point must be a normal instruction\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5101, __PRETTY_FUNCTION__))
;
5102
5103 // Then, climb up the immediate dominator tree as far as we can go while
5104 // still being dominated by the input positions.
5105 BasicBlock::iterator IP = HoistInsertPosition(LowestIP, Inputs);
5106
5107 // Don't insert instructions before PHI nodes.
5108 while (isa<PHINode>(IP)) ++IP;
5109
5110 // Ignore landingpad instructions.
5111 while (IP->isEHPad()) ++IP;
5112
5113 // Ignore debug intrinsics.
5114 while (isa<DbgInfoIntrinsic>(IP)) ++IP;
5115
5116 // Set IP below instructions recently inserted by SCEVExpander. This keeps the
5117 // IP consistent across expansions and allows the previously inserted
5118 // instructions to be reused by subsequent expansion.
5119 while (Rewriter.isInsertedInstruction(&*IP) && IP != LowestIP)
5120 ++IP;
5121
5122 return IP;
5123}
5124
5125/// Emit instructions for the leading candidate expression for this LSRUse (this
5126/// is called "expanding").
5127Value *LSRInstance::Expand(const LSRUse &LU, const LSRFixup &LF,
5128 const Formula &F, BasicBlock::iterator IP,
5129 SCEVExpander &Rewriter,
5130 SmallVectorImpl<WeakTrackingVH> &DeadInsts) const {
5131 if (LU.RigidFormula)
10
Assuming field 'RigidFormula' is false
11
Taking false branch
5132 return LF.OperandValToReplace;
5133
5134 // Determine an input position which will be dominated by the operands and
5135 // which will dominate the result.
5136 IP = AdjustInsertPositionForExpand(IP, LF, LU, Rewriter);
5137 Rewriter.setInsertPoint(&*IP);
5138
5139 // Inform the Rewriter if we have a post-increment use, so that it can
5140 // perform an advantageous expansion.
5141 Rewriter.setPostInc(LF.PostIncLoops);
5142
5143 // This is the type that the user actually needs.
5144 Type *OpTy = LF.OperandValToReplace->getType();
12
Called C++ object pointer is null
5145 // This will be the type that we'll initially expand to.
5146 Type *Ty = F.getType();
5147 if (!Ty)
5148 // No type known; just expand directly to the ultimate type.
5149 Ty = OpTy;
5150 else if (SE.getEffectiveSCEVType(Ty) == SE.getEffectiveSCEVType(OpTy))
5151 // Expand directly to the ultimate type if it's the right size.
5152 Ty = OpTy;
5153 // This is the type to do integer arithmetic in.
5154 Type *IntTy = SE.getEffectiveSCEVType(Ty);
5155
5156 // Build up a list of operands to add together to form the full base.
5157 SmallVector<const SCEV *, 8> Ops;
5158
5159 // Expand the BaseRegs portion.
5160 for (const SCEV *Reg : F.BaseRegs) {
5161 assert(!Reg->isZero() && "Zero allocated in a base register!")((!Reg->isZero() && "Zero allocated in a base register!"
) ? static_cast<void> (0) : __assert_fail ("!Reg->isZero() && \"Zero allocated in a base register!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5161, __PRETTY_FUNCTION__))
;
5162
5163 // If we're expanding for a post-inc user, make the post-inc adjustment.
5164 Reg = denormalizeForPostIncUse(Reg, LF.PostIncLoops, SE);
5165 Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, nullptr)));
5166 }
5167
5168 // Expand the ScaledReg portion.
5169 Value *ICmpScaledV = nullptr;
5170 if (F.Scale != 0) {
5171 const SCEV *ScaledS = F.ScaledReg;
5172
5173 // If we're expanding for a post-inc user, make the post-inc adjustment.
5174 PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops);
5175 ScaledS = denormalizeForPostIncUse(ScaledS, Loops, SE);
5176
5177 if (LU.Kind == LSRUse::ICmpZero) {
5178 // Expand ScaleReg as if it was part of the base regs.
5179 if (F.Scale == 1)
5180 Ops.push_back(
5181 SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr)));
5182 else {
5183 // An interesting way of "folding" with an icmp is to use a negated
5184 // scale, which we'll implement by inserting it into the other operand
5185 // of the icmp.
5186 assert(F.Scale == -1 &&((F.Scale == -1 && "The only scale supported by ICmpZero uses is -1!"
) ? static_cast<void> (0) : __assert_fail ("F.Scale == -1 && \"The only scale supported by ICmpZero uses is -1!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5187, __PRETTY_FUNCTION__))
5187 "The only scale supported by ICmpZero uses is -1!")((F.Scale == -1 && "The only scale supported by ICmpZero uses is -1!"
) ? static_cast<void> (0) : __assert_fail ("F.Scale == -1 && \"The only scale supported by ICmpZero uses is -1!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5187, __PRETTY_FUNCTION__))
;
5188 ICmpScaledV = Rewriter.expandCodeFor(ScaledS, nullptr);
5189 }
5190 } else {
5191 // Otherwise just expand the scaled register and an explicit scale,
5192 // which is expected to be matched as part of the address.
5193
5194 // Flush the operand list to suppress SCEVExpander hoisting address modes.
5195 // Unless the addressing mode will not be folded.
5196 if (!Ops.empty() && LU.Kind == LSRUse::Address &&
5197 isAMCompletelyFolded(TTI, LU, F)) {
5198 Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), nullptr);
5199 Ops.clear();
5200 Ops.push_back(SE.getUnknown(FullV));
5201 }
5202 ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr));
5203 if (F.Scale != 1)
5204 ScaledS =
5205 SE.getMulExpr(ScaledS, SE.getConstant(ScaledS->getType(), F.Scale));
5206 Ops.push_back(ScaledS);
5207 }
5208 }
5209
5210 // Expand the GV portion.
5211 if (F.BaseGV) {
5212 // Flush the operand list to suppress SCEVExpander hoisting.
5213 if (!Ops.empty()) {
5214 Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty);
5215 Ops.clear();
5216 Ops.push_back(SE.getUnknown(FullV));
5217 }
5218 Ops.push_back(SE.getUnknown(F.BaseGV));
5219 }
5220
5221 // Flush the operand list to suppress SCEVExpander hoisting of both folded and
5222 // unfolded offsets. LSR assumes they both live next to their uses.
5223 if (!Ops.empty()) {
5224 Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty);
5225 Ops.clear();
5226 Ops.push_back(SE.getUnknown(FullV));
5227 }
5228
5229 // Expand the immediate portion.
5230 int64_t Offset = (uint64_t)F.BaseOffset + LF.Offset;
5231 if (Offset != 0) {
5232 if (LU.Kind == LSRUse::ICmpZero) {
5233 // The other interesting way of "folding" with an ICmpZero is to use a
5234 // negated immediate.
5235 if (!ICmpScaledV)
5236 ICmpScaledV = ConstantInt::get(IntTy, -(uint64_t)Offset);
5237 else {
5238 Ops.push_back(SE.getUnknown(ICmpScaledV));
5239 ICmpScaledV = ConstantInt::get(IntTy, Offset);
5240 }
5241 } else {
5242 // Just add the immediate values. These again are expected to be matched
5243 // as part of the address.
5244 Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy, Offset)));
5245 }
5246 }
5247
5248 // Expand the unfolded offset portion.
5249 int64_t UnfoldedOffset = F.UnfoldedOffset;
5250 if (UnfoldedOffset != 0) {
5251 // Just add the immediate values.
5252 Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy,
5253 UnfoldedOffset)));
5254 }
5255
5256 // Emit instructions summing all the operands.
5257 const SCEV *FullS = Ops.empty() ?
5258 SE.getConstant(IntTy, 0) :
5259 SE.getAddExpr(Ops);
5260 Value *FullV = Rewriter.expandCodeFor(FullS, Ty);
5261
5262 // We're done expanding now, so reset the rewriter.
5263 Rewriter.clearPostInc();
5264
5265 // An ICmpZero Formula represents an ICmp which we're handling as a
5266 // comparison against zero. Now that we've expanded an expression for that
5267 // form, update the ICmp's other operand.
5268 if (LU.Kind == LSRUse::ICmpZero) {
5269 ICmpInst *CI = cast<ICmpInst>(LF.UserInst);
5270 DeadInsts.emplace_back(CI->getOperand(1));
5271 assert(!F.BaseGV && "ICmp does not support folding a global value and "((!F.BaseGV && "ICmp does not support folding a global value and "
"a scale at the same time!") ? static_cast<void> (0) :
__assert_fail ("!F.BaseGV && \"ICmp does not support folding a global value and \" \"a scale at the same time!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5272, __PRETTY_FUNCTION__))
5272 "a scale at the same time!")((!F.BaseGV && "ICmp does not support folding a global value and "
"a scale at the same time!") ? static_cast<void> (0) :
__assert_fail ("!F.BaseGV && \"ICmp does not support folding a global value and \" \"a scale at the same time!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5272, __PRETTY_FUNCTION__))
;
5273 if (F.Scale == -1) {
5274 if (ICmpScaledV->getType() != OpTy) {
5275 Instruction *Cast =
5276 CastInst::Create(CastInst::getCastOpcode(ICmpScaledV, false,
5277 OpTy, false),
5278 ICmpScaledV, OpTy, "tmp", CI);
5279 ICmpScaledV = Cast;
5280 }
5281 CI->setOperand(1, ICmpScaledV);
5282 } else {
5283 // A scale of 1 means that the scale has been expanded as part of the
5284 // base regs.
5285 assert((F.Scale == 0 || F.Scale == 1) &&(((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and "
"a scale at the same time!") ? static_cast<void> (0) :
__assert_fail ("(F.Scale == 0 || F.Scale == 1) && \"ICmp does not support folding a global value and \" \"a scale at the same time!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5287, __PRETTY_FUNCTION__))
5286 "ICmp does not support folding a global value and "(((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and "
"a scale at the same time!") ? static_cast<void> (0) :
__assert_fail ("(F.Scale == 0 || F.Scale == 1) && \"ICmp does not support folding a global value and \" \"a scale at the same time!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5287, __PRETTY_FUNCTION__))
5287 "a scale at the same time!")(((F.Scale == 0 || F.Scale == 1) && "ICmp does not support folding a global value and "
"a scale at the same time!") ? static_cast<void> (0) :
__assert_fail ("(F.Scale == 0 || F.Scale == 1) && \"ICmp does not support folding a global value and \" \"a scale at the same time!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5287, __PRETTY_FUNCTION__))
;
5288 Constant *C = ConstantInt::getSigned(SE.getEffectiveSCEVType(OpTy),
5289 -(uint64_t)Offset);
5290 if (C->getType() != OpTy)
5291 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
5292 OpTy, false),
5293 C, OpTy);
5294
5295 CI->setOperand(1, C);
5296 }
5297 }
5298
5299 return FullV;
5300}
5301
5302/// Helper for Rewrite. PHI nodes are special because the use of their operands
5303/// effectively happens in their predecessor blocks, so the expression may need
5304/// to be expanded in multiple places.
5305void LSRInstance::RewriteForPHI(
5306 PHINode *PN, const LSRUse &LU, const LSRFixup &LF, const Formula &F,
5307 SCEVExpander &Rewriter, SmallVectorImpl<WeakTrackingVH> &DeadInsts) const {
5308 DenseMap<BasicBlock *, Value *> Inserted;
5309 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
1
Assuming 'i' is not equal to 'e'
2
Loop condition is true. Entering loop body
5310 if (PN->getIncomingValue(i) == LF.OperandValToReplace) {
3
Assuming pointer value is null
4
Taking true branch
5311 bool needUpdateFixups = false;
5312 BasicBlock *BB = PN->getIncomingBlock(i);
5313
5314 // If this is a critical edge, split the edge so that we do not insert
5315 // the code on all predecessor/successor paths. We do this unless this
5316 // is the canonical backedge for this loop, which complicates post-inc
5317 // users.
5318 if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 &&
5
Assuming 'e' is equal to 1
6
Taking false branch
5319 !isa<IndirectBrInst>(BB->getTerminator()) &&
5320 !isa<CatchSwitchInst>(BB->getTerminator())) {
5321 BasicBlock *Parent = PN->getParent();
5322 Loop *PNLoop = LI.getLoopFor(Parent);
5323 if (!PNLoop || Parent != PNLoop->getHeader()) {
5324 // Split the critical edge.
5325 BasicBlock *NewBB = nullptr;
5326 if (!Parent->isLandingPad()) {
5327 NewBB = SplitCriticalEdge(BB, Parent,
5328 CriticalEdgeSplittingOptions(&DT, &LI)
5329 .setMergeIdenticalEdges()
5330 .setKeepOneInputPHIs());
5331 } else {
5332 SmallVector<BasicBlock*, 2> NewBBs;
5333 SplitLandingPadPredecessors(Parent, BB, "", "", NewBBs, &DT, &LI);
5334 NewBB = NewBBs[0];
5335 }
5336 // If NewBB==NULL, then SplitCriticalEdge refused to split because all
5337 // phi predecessors are identical. The simple thing to do is skip
5338 // splitting in this case rather than complicate the API.
5339 if (NewBB) {
5340 // If PN is outside of the loop and BB is in the loop, we want to
5341 // move the block to be immediately before the PHI block, not
5342 // immediately after BB.
5343 if (L->contains(BB) && !L->contains(PN))
5344 NewBB->moveBefore(PN->getParent());
5345
5346 // Splitting the edge can reduce the number of PHI entries we have.
5347 e = PN->getNumIncomingValues();
5348 BB = NewBB;
5349 i = PN->getBasicBlockIndex(BB);
5350
5351 needUpdateFixups = true;
5352 }
5353 }
5354 }
5355
5356 std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair =
5357 Inserted.insert(std::make_pair(BB, static_cast<Value *>(nullptr)));
5358 if (!Pair.second)
7
Assuming field 'second' is true
8
Taking false branch
5359 PN->setIncomingValue(i, Pair.first->second);
5360 else {
5361 Value *FullV = Expand(LU, LF, F, BB->getTerminator()->getIterator(),
9
Calling 'LSRInstance::Expand'
5362 Rewriter, DeadInsts);
5363
5364 // If this is reuse-by-noop-cast, insert the noop cast.
5365 Type *OpTy = LF.OperandValToReplace->getType();
5366 if (FullV->getType() != OpTy)
5367 FullV =
5368 CastInst::Create(CastInst::getCastOpcode(FullV, false,
5369 OpTy, false),
5370 FullV, LF.OperandValToReplace->getType(),
5371 "tmp", BB->getTerminator());
5372
5373 PN->setIncomingValue(i, FullV);
5374 Pair.first->second = FullV;
5375 }
5376
5377 // If LSR splits critical edge and phi node has other pending
5378 // fixup operands, we need to update those pending fixups. Otherwise
5379 // formulae will not be implemented completely and some instructions
5380 // will not be eliminated.
5381 if (needUpdateFixups) {
5382 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx)
5383 for (LSRFixup &Fixup : Uses[LUIdx].Fixups)
5384 // If fixup is supposed to rewrite some operand in the phi
5385 // that was just updated, it may be already moved to
5386 // another phi node. Such fixup requires update.
5387 if (Fixup.UserInst == PN) {
5388 // Check if the operand we try to replace still exists in the
5389 // original phi.
5390 bool foundInOriginalPHI = false;
5391 for (const auto &val : PN->incoming_values())
5392 if (val == Fixup.OperandValToReplace) {
5393 foundInOriginalPHI = true;
5394 break;
5395 }
5396
5397 // If fixup operand found in original PHI - nothing to do.
5398 if (foundInOriginalPHI)
5399 continue;
5400
5401 // Otherwise it might be moved to another PHI and requires update.
5402 // If fixup operand not found in any of the incoming blocks that
5403 // means we have already rewritten it - nothing to do.
5404 for (const auto &Block : PN->blocks())
5405 for (BasicBlock::iterator I = Block->begin(); isa<PHINode>(I);
5406 ++I) {
5407 PHINode *NewPN = cast<PHINode>(I);
5408 for (const auto &val : NewPN->incoming_values())
5409 if (val == Fixup.OperandValToReplace)
5410 Fixup.UserInst = NewPN;
5411 }
5412 }
5413 }
5414 }
5415}
5416
5417/// Emit instructions for the leading candidate expression for this LSRUse (this
5418/// is called "expanding"), and update the UserInst to reference the newly
5419/// expanded value.
5420void LSRInstance::Rewrite(const LSRUse &LU, const LSRFixup &LF,
5421 const Formula &F, SCEVExpander &Rewriter,
5422 SmallVectorImpl<WeakTrackingVH> &DeadInsts) const {
5423 // First, find an insertion point that dominates UserInst. For PHI nodes,
5424 // find the nearest block which dominates all the relevant uses.
5425 if (PHINode *PN = dyn_cast<PHINode>(LF.UserInst)) {
5426 RewriteForPHI(PN, LU, LF, F, Rewriter, DeadInsts);
5427 } else {
5428 Value *FullV =
5429 Expand(LU, LF, F, LF.UserInst->getIterator(), Rewriter, DeadInsts);
5430
5431 // If this is reuse-by-noop-cast, insert the noop cast.
5432 Type *OpTy = LF.OperandValToReplace->getType();
5433 if (FullV->getType() != OpTy) {
5434 Instruction *Cast =
5435 CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false),
5436 FullV, OpTy, "tmp", LF.UserInst);
5437 FullV = Cast;
5438 }
5439
5440 // Update the user. ICmpZero is handled specially here (for now) because
5441 // Expand may have updated one of the operands of the icmp already, and
5442 // its new value may happen to be equal to LF.OperandValToReplace, in
5443 // which case doing replaceUsesOfWith leads to replacing both operands
5444 // with the same value. TODO: Reorganize this.
5445 if (LU.Kind == LSRUse::ICmpZero)
5446 LF.UserInst->setOperand(0, FullV);
5447 else
5448 LF.UserInst->replaceUsesOfWith(LF.OperandValToReplace, FullV);
5449 }
5450
5451 DeadInsts.emplace_back(LF.OperandValToReplace);
5452}
5453
5454/// Rewrite all the fixup locations with new values, following the chosen
5455/// solution.
5456void LSRInstance::ImplementSolution(
5457 const SmallVectorImpl<const Formula *> &Solution) {
5458 // Keep track of instructions we may have made dead, so that
5459 // we can remove them after we are done working.
5460 SmallVector<WeakTrackingVH, 16> DeadInsts;
5461
5462 SCEVExpander Rewriter(SE, L->getHeader()->getModule()->getDataLayout(),
5463 "lsr");
5464#ifndef NDEBUG
5465 Rewriter.setDebugType(DEBUG_TYPE"loop-reduce");
5466#endif
5467 Rewriter.disableCanonicalMode();
5468 Rewriter.enableLSRMode();
5469 Rewriter.setIVIncInsertPos(L, IVIncInsertPos);
5470
5471 // Mark phi nodes that terminate chains so the expander tries to reuse them.
5472 for (const IVChain &Chain : IVChainVec) {
5473 if (PHINode *PN = dyn_cast<PHINode>(Chain.tailUserInst()))
5474 Rewriter.setChainedPhi(PN);
5475 }
5476
5477 // Expand the new value definitions and update the users.
5478 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx)
5479 for (const LSRFixup &Fixup : Uses[LUIdx].Fixups) {
5480 Rewrite(Uses[LUIdx], Fixup, *Solution[LUIdx], Rewriter, DeadInsts);
5481 Changed = true;
5482 }
5483
5484 for (const IVChain &Chain : IVChainVec) {
5485 GenerateIVChain(Chain, Rewriter, DeadInsts);
5486 Changed = true;
5487 }
5488 // Clean up after ourselves. This must be done before deleting any
5489 // instructions.
5490 Rewriter.clear();
5491
5492 Changed |= DeleteTriviallyDeadInstructions(DeadInsts);
5493}
5494
5495LSRInstance::LSRInstance(Loop *L, IVUsers &IU, ScalarEvolution &SE,
5496 DominatorTree &DT, LoopInfo &LI,
5497 const TargetTransformInfo &TTI, AssumptionCache &AC,
5498 TargetLibraryInfo &LibInfo)
5499 : IU(IU), SE(SE), DT(DT), LI(LI), AC(AC), LibInfo(LibInfo), TTI(TTI), L(L),
5500 FavorBackedgeIndex(EnableBackedgeIndexing &&
5501 TTI.shouldFavorBackedgeIndex(L)) {
5502 // If LoopSimplify form is not available, stay out of trouble.
5503 if (!L->isLoopSimplifyForm())
5504 return;
5505
5506 // If there's no interesting work to be done, bail early.
5507 if (IU.empty()) return;
5508
5509 // If there's too much analysis to be done, bail early. We won't be able to
5510 // model the problem anyway.
5511 unsigned NumUsers = 0;
5512 for (const IVStrideUse &U : IU) {
5513 if (++NumUsers > MaxIVUsers) {
5514 (void)U;
5515 LLVM_DEBUG(dbgs() << "LSR skipping loop, too many IV Users in " << Udo { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR skipping loop, too many IV Users in "
<< U << "\n"; } } while (false)
5516 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR skipping loop, too many IV Users in "
<< U << "\n"; } } while (false)
;
5517 return;
5518 }
5519 // Bail out if we have a PHI on an EHPad that gets a value from a
5520 // CatchSwitchInst. Because the CatchSwitchInst cannot be split, there is
5521 // no good place to stick any instructions.
5522 if (auto *PN = dyn_cast<PHINode>(U.getUser())) {
5523 auto *FirstNonPHI = PN->getParent()->getFirstNonPHI();
5524 if (isa<FuncletPadInst>(FirstNonPHI) ||
5525 isa<CatchSwitchInst>(FirstNonPHI))
5526 for (BasicBlock *PredBB : PN->blocks())
5527 if (isa<CatchSwitchInst>(PredBB->getFirstNonPHI()))
5528 return;
5529 }
5530 }
5531
5532#ifndef NDEBUG
5533 // All dominating loops must have preheaders, or SCEVExpander may not be able
5534 // to materialize an AddRecExpr whose Start is an outer AddRecExpr.
5535 //
5536 // IVUsers analysis should only create users that are dominated by simple loop
5537 // headers. Since this loop should dominate all of its users, its user list
5538 // should be empty if this loop itself is not within a simple loop nest.
5539 for (DomTreeNode *Rung = DT.getNode(L->getLoopPreheader());
5540 Rung; Rung = Rung->getIDom()) {
5541 BasicBlock *BB = Rung->getBlock();
5542 const Loop *DomLoop = LI.getLoopFor(BB);
5543 if (DomLoop && DomLoop->getHeader() == BB) {
5544 assert(DomLoop->getLoopPreheader() && "LSR needs a simplified loop nest")((DomLoop->getLoopPreheader() && "LSR needs a simplified loop nest"
) ? static_cast<void> (0) : __assert_fail ("DomLoop->getLoopPreheader() && \"LSR needs a simplified loop nest\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5544, __PRETTY_FUNCTION__))
;
5545 }
5546 }
5547#endif // DEBUG
5548
5549 LLVM_DEBUG(dbgs() << "\nLSR on loop ";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader
()->printAsOperand(dbgs(), false); dbgs() << ":\n"; }
} while (false)
5550 L->getHeader()->printAsOperand(dbgs(), /*PrintType=*/false);do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader
()->printAsOperand(dbgs(), false); dbgs() << ":\n"; }
} while (false)
5551 dbgs() << ":\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader
()->printAsOperand(dbgs(), false); dbgs() << ":\n"; }
} while (false)
;
5552
5553 // First, perform some low-level loop optimizations.
5554 OptimizeShadowIV();
5555 OptimizeLoopTermCond();
5556
5557 // If loop preparation eliminates all interesting IV users, bail.
5558 if (IU.empty()) return;
5559
5560 // Skip nested loops until we can model them better with formulae.
5561 if (!L->empty()) {
5562 LLVM_DEBUG(dbgs() << "LSR skipping outer loop " << *L << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR skipping outer loop "
<< *L << "\n"; } } while (false)
;
5563 return;
5564 }
5565
5566 // Start collecting data and preparing for the solver.
5567 CollectChains();
5568 CollectInterestingTypesAndFactors();
5569 CollectFixupsAndInitialFormulae();
5570 CollectLoopInvariantFixupsAndFormulae();
5571
5572 if (Uses.empty())
5573 return;
5574
5575 LLVM_DEBUG(dbgs() << "LSR found " << Uses.size() << " uses:\n";do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR found " << Uses
.size() << " uses:\n"; print_uses(dbgs()); } } while (false
)
5576 print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR found " << Uses
.size() << " uses:\n"; print_uses(dbgs()); } } while (false
)
;
5577
5578 // Now use the reuse data to generate a bunch of interesting ways
5579 // to formulate the values needed for the uses.
5580 GenerateAllReuseFormulae();
5581
5582 FilterOutUndesirableDedicatedRegisters();
5583 NarrowSearchSpaceUsingHeuristics();
5584
5585 SmallVector<const Formula *, 8> Solution;
5586 Solve(Solution);
5587
5588 // Release memory that is no longer needed.
5589 Factors.clear();
5590 Types.clear();
5591 RegUses.clear();
5592
5593 if (Solution.empty())
5594 return;
5595
5596#ifndef NDEBUG
5597 // Formulae should be legal.
5598 for (const LSRUse &LU : Uses) {
5599 for (const Formula &F : LU.Formulae)
5600 assert(isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy
, F) && "Illegal formula generated!") ? static_cast<
void> (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Illegal formula generated!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5601, __PRETTY_FUNCTION__))
5601 F) && "Illegal formula generated!")((isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy
, F) && "Illegal formula generated!") ? static_cast<
void> (0) : __assert_fail ("isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F) && \"Illegal formula generated!\""
, "/build/llvm-toolchain-snapshot-10~svn374877/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5601, __PRETTY_FUNCTION__))
;
5602 };
5603#endif
5604
5605 // Now that we've decided what we want, make it so.
5606 ImplementSolution(Solution);
5607}
5608
5609#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
5610void LSRInstance::print_factors_and_types(raw_ostream &OS) const {
5611 if (Factors.empty() && Types.empty()) return;
5612
5613 OS << "LSR has identified the following interesting factors and types: ";
5614 bool First = true;
5615
5616 for (int64_t Factor : Factors) {
5617 if (!First) OS << ", ";
5618 First = false;
5619 OS << '*' << Factor;
5620 }
5621
5622 for (Type *Ty : Types) {
5623 if (!First) OS << ", ";
5624 First = false;
5625 OS << '(' << *Ty << ')';
5626 }
5627 OS << '\n';
5628}
5629
5630void LSRInstance::print_fixups(raw_ostream &OS) const {
5631 OS << "LSR is examining the following fixup sites:\n";
5632 for (const LSRUse &LU : Uses)
5633 for (const LSRFixup &LF : LU.Fixups) {
5634 dbgs() << " ";
5635 LF.print(OS);
5636 OS << '\n';
5637 }
5638}
5639
5640void LSRInstance::print_uses(raw_ostream &OS) const {
5641 OS << "LSR is examining the following uses:\n";
5642 for (const LSRUse &LU : Uses) {
5643 dbgs() << " ";
5644 LU.print(OS);
5645 OS << '\n';
5646 for (const Formula &F : LU.Formulae) {
5647 OS << " ";
5648 F.print(OS);
5649 OS << '\n';
5650 }
5651 }
5652}
5653
5654void LSRInstance::print(raw_ostream &OS) const {
5655 print_factors_and_types(OS);
5656 print_fixups(OS);
5657 print_uses(OS);
5658}
5659
5660LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void LSRInstance::dump() const {
5661 print(errs()); errs() << '\n';
5662}
5663#endif
5664
5665namespace {
5666
5667class LoopStrengthReduce : public LoopPass {
5668public:
5669 static char ID; // Pass ID, replacement for typeid
5670
5671 LoopStrengthReduce();
5672
5673private:
5674 bool runOnLoop(Loop *L, LPPassManager &LPM) override;
5675 void getAnalysisUsage(AnalysisUsage &AU) const override;
5676};
5677
5678} // end anonymous namespace
5679
5680LoopStrengthReduce::LoopStrengthReduce() : LoopPass(ID) {
5681 initializeLoopStrengthReducePass(*PassRegistry::getPassRegistry());
5682}
5683
5684void LoopStrengthReduce::getAnalysisUsage(AnalysisUsage &AU) const {
5685 // We split critical edges, so we change the CFG. However, we do update
5686 // many analyses if they are around.
5687 AU.addPreservedID(LoopSimplifyID);
5688
5689 AU.addRequired<LoopInfoWrapperPass>();
5690 AU.addPreserved<LoopInfoWrapperPass>();
5691 AU.addRequiredID(LoopSimplifyID);
5692 AU.addRequired<DominatorTreeWrapperPass>();
5693 AU.addPreserved<DominatorTreeWrapperPass>();
5694 AU.addRequired<ScalarEvolutionWrapperPass>();
5695 AU.addPreserved<ScalarEvolutionWrapperPass>();
5696 AU.addRequired<AssumptionCacheTracker>();
5697 AU.addRequired<TargetLibraryInfoWrapperPass>();
5698 // Requiring LoopSimplify a second time here prevents IVUsers from running
5699 // twice, since LoopSimplify was invalidated by running ScalarEvolution.
5700 AU.addRequiredID(LoopSimplifyID);
5701 AU.addRequired<IVUsersWrapperPass>();
5702 AU.addPreserved<IVUsersWrapperPass>();
5703 AU.addRequired<TargetTransformInfoWrapperPass>();
5704}
5705
5706static bool ReduceLoopStrength(Loop *L, IVUsers &IU, ScalarEvolution &SE,
5707 DominatorTree &DT, LoopInfo &LI,
5708 const TargetTransformInfo &TTI,
5709 AssumptionCache &AC,
5710 TargetLibraryInfo &LibInfo) {
5711
5712 bool Changed = false;
5713
5714 // Run the main LSR transformation.
5715 Changed |= LSRInstance(L, IU, SE, DT, LI, TTI, AC, LibInfo).getChanged();
5716
5717 // Remove any extra phis created by processing inner loops.
5718 Changed |= DeleteDeadPHIs(L->getHeader());
5719 if (EnablePhiElim && L->isLoopSimplifyForm()) {
5720 SmallVector<WeakTrackingVH, 16> DeadInsts;
5721 const DataLayout &DL = L->getHeader()->getModule()->getDataLayout();
5722 SCEVExpander Rewriter(SE, DL, "lsr");
5723#ifndef NDEBUG
5724 Rewriter.setDebugType(DEBUG_TYPE"loop-reduce");
5725#endif
5726 unsigned numFolded = Rewriter.replaceCongruentIVs(L, &DT, DeadInsts, &TTI);
5727 if (numFolded) {
5728 Changed = true;
5729 DeleteTriviallyDeadInstructions(DeadInsts);
5730 DeleteDeadPHIs(L->getHeader());
5731 }
5732 }
5733 return Changed;
5734}
5735
5736bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager & /*LPM*/) {
5737 if (skipLoop(L))
5738 return false;
5739
5740 auto &IU = getAnalysis<IVUsersWrapperPass>().getIU();
5741 auto &SE = getAnalysis<ScalarEvolutionWrapperPass>().getSE();
5742 auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
5743 auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
5744 const auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(
5745 *L->getHeader()->getParent());
5746 auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(
5747 *L->getHeader()->getParent());
5748 auto &LibInfo = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(
5749 *L->getHeader()->getParent());
5750 return ReduceLoopStrength(L, IU, SE, DT, LI, TTI, AC, LibInfo);
5751}
5752
5753PreservedAnalyses LoopStrengthReducePass::run(Loop &L, LoopAnalysisManager &AM,
5754 LoopStandardAnalysisResults &AR,
5755 LPMUpdater &) {
5756 if (!ReduceLoopStrength(&L, AM.getResult<IVUsersAnalysis>(L, AR), AR.SE,
5757 AR.DT, AR.LI, AR.TTI, AR.AC, AR.TLI))
5758 return PreservedAnalyses::all();
5759
5760 return getLoopPassPreservedAnalyses();
5761}
5762
5763char LoopStrengthReduce::ID = 0;
5764
5765INITIALIZE_PASS_BEGIN(LoopStrengthReduce, "loop-reduce",static void *initializeLoopStrengthReducePassOnce(PassRegistry
&Registry) {
5766 "Loop Strength Reduction", false, false)static void *initializeLoopStrengthReducePassOnce(PassRegistry
&am