Bug Summary

File:llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
Warning:line 5424, column 22
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -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 -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -fno-split-dwarf-inlining -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-12/lib/clang/12.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/build-llvm/lib/Transforms/Scalar -I /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar -I /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/build-llvm/include -I /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/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-12/lib/clang/12.0.0/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-12~++20200927111121+5811d723998/build-llvm/lib/Transforms/Scalar -fdebug-prefix-map=/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2020-09-28-092409-31635-1 -x c++ /build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/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/AssumptionCache.h"
69#include "llvm/Analysis/IVUsers.h"
70#include "llvm/Analysis/LoopAnalysisManager.h"
71#include "llvm/Analysis/LoopInfo.h"
72#include "llvm/Analysis/LoopPass.h"
73#include "llvm/Analysis/MemorySSA.h"
74#include "llvm/Analysis/MemorySSAUpdater.h"
75#include "llvm/Analysis/ScalarEvolution.h"
76#include "llvm/Analysis/ScalarEvolutionExpressions.h"
77#include "llvm/Analysis/ScalarEvolutionNormalization.h"
78#include "llvm/Analysis/TargetTransformInfo.h"
79#include "llvm/Config/llvm-config.h"
80#include "llvm/IR/BasicBlock.h"
81#include "llvm/IR/Constant.h"
82#include "llvm/IR/Constants.h"
83#include "llvm/IR/DerivedTypes.h"
84#include "llvm/IR/Dominators.h"
85#include "llvm/IR/GlobalValue.h"
86#include "llvm/IR/IRBuilder.h"
87#include "llvm/IR/InstrTypes.h"
88#include "llvm/IR/Instruction.h"
89#include "llvm/IR/Instructions.h"
90#include "llvm/IR/IntrinsicInst.h"
91#include "llvm/IR/Intrinsics.h"
92#include "llvm/IR/Module.h"
93#include "llvm/IR/OperandTraits.h"
94#include "llvm/IR/Operator.h"
95#include "llvm/IR/PassManager.h"
96#include "llvm/IR/Type.h"
97#include "llvm/IR/Use.h"
98#include "llvm/IR/User.h"
99#include "llvm/IR/Value.h"
100#include "llvm/IR/ValueHandle.h"
101#include "llvm/InitializePasses.h"
102#include "llvm/Pass.h"
103#include "llvm/Support/Casting.h"
104#include "llvm/Support/CommandLine.h"
105#include "llvm/Support/Compiler.h"
106#include "llvm/Support/Debug.h"
107#include "llvm/Support/ErrorHandling.h"
108#include "llvm/Support/MathExtras.h"
109#include "llvm/Support/raw_ostream.h"
110#include "llvm/Transforms/Scalar.h"
111#include "llvm/Transforms/Utils.h"
112#include "llvm/Transforms/Utils/BasicBlockUtils.h"
113#include "llvm/Transforms/Utils/Local.h"
114#include "llvm/Transforms/Utils/ScalarEvolutionExpander.h"
115#include <algorithm>
116#include <cassert>
117#include <cstddef>
118#include <cstdint>
119#include <cstdlib>
120#include <iterator>
121#include <limits>
122#include <map>
123#include <numeric>
124#include <utility>
125
126using namespace llvm;
127
128#define DEBUG_TYPE"loop-reduce" "loop-reduce"
129
130/// MaxIVUsers is an arbitrary threshold that provides an early opportunity for
131/// bail out. This threshold is far beyond the number of users that LSR can
132/// conceivably solve, so it should not affect generated code, but catches the
133/// worst cases before LSR burns too much compile time and stack space.
134static const unsigned MaxIVUsers = 200;
135
136// Temporary flag to cleanup congruent phis after LSR phi expansion.
137// It's currently disabled until we can determine whether it's truly useful or
138// not. The flag should be removed after the v3.0 release.
139// This is now needed for ivchains.
140static cl::opt<bool> EnablePhiElim(
141 "enable-lsr-phielim", cl::Hidden, cl::init(true),
142 cl::desc("Enable LSR phi elimination"));
143
144// The flag adds instruction count to solutions cost comparision.
145static cl::opt<bool> InsnsCost(
146 "lsr-insns-cost", cl::Hidden, cl::init(true),
147 cl::desc("Add instruction count to a LSR cost model"));
148
149// Flag to choose how to narrow complex lsr solution
150static cl::opt<bool> LSRExpNarrow(
151 "lsr-exp-narrow", cl::Hidden, cl::init(false),
152 cl::desc("Narrow LSR complex solution using"
153 " expectation of registers number"));
154
155// Flag to narrow search space by filtering non-optimal formulae with
156// the same ScaledReg and Scale.
157static cl::opt<bool> FilterSameScaledReg(
158 "lsr-filter-same-scaled-reg", cl::Hidden, cl::init(true),
159 cl::desc("Narrow LSR search space by filtering non-optimal formulae"
160 " with the same ScaledReg and Scale"));
161
162static cl::opt<bool> EnableBackedgeIndexing(
163 "lsr-backedge-indexing", cl::Hidden, cl::init(true),
164 cl::desc("Enable the generation of cross iteration indexed memops"));
165
166static cl::opt<unsigned> ComplexityLimit(
167 "lsr-complexity-limit", cl::Hidden,
168 cl::init(std::numeric_limits<uint16_t>::max()),
169 cl::desc("LSR search space complexity limit"));
170
171static cl::opt<unsigned> SetupCostDepthLimit(
172 "lsr-setupcost-depth-limit", cl::Hidden, cl::init(7),
173 cl::desc("The limit on recursion depth for LSRs setup cost"));
174
175#ifndef NDEBUG
176// Stress test IV chain generation.
177static cl::opt<bool> StressIVChain(
178 "stress-ivchain", cl::Hidden, cl::init(false),
179 cl::desc("Stress test LSR IV chains"));
180#else
181static bool StressIVChain = false;
182#endif
183
184namespace {
185
186struct MemAccessTy {
187 /// Used in situations where the accessed memory type is unknown.
188 static const unsigned UnknownAddressSpace =
189 std::numeric_limits<unsigned>::max();
190
191 Type *MemTy = nullptr;
192 unsigned AddrSpace = UnknownAddressSpace;
193
194 MemAccessTy() = default;
195 MemAccessTy(Type *Ty, unsigned AS) : MemTy(Ty), AddrSpace(AS) {}
196
197 bool operator==(MemAccessTy Other) const {
198 return MemTy == Other.MemTy && AddrSpace == Other.AddrSpace;
199 }
200
201 bool operator!=(MemAccessTy Other) const { return !(*this == Other); }
202
203 static MemAccessTy getUnknown(LLVMContext &Ctx,
204 unsigned AS = UnknownAddressSpace) {
205 return MemAccessTy(Type::getVoidTy(Ctx), AS);
206 }
207
208 Type *getType() { return MemTy; }
209};
210
211/// This class holds data which is used to order reuse candidates.
212class RegSortData {
213public:
214 /// This represents the set of LSRUse indices which reference
215 /// a particular register.
216 SmallBitVector UsedByIndices;
217
218 void print(raw_ostream &OS) const;
219 void dump() const;
220};
221
222} // end anonymous namespace
223
224#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
225void RegSortData::print(raw_ostream &OS) const {
226 OS << "[NumUses=" << UsedByIndices.count() << ']';
227}
228
229LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void RegSortData::dump() const {
230 print(errs()); errs() << '\n';
231}
232#endif
233
234namespace {
235
236/// Map register candidates to information about how they are used.
237class RegUseTracker {
238 using RegUsesTy = DenseMap<const SCEV *, RegSortData>;
239
240 RegUsesTy RegUsesMap;
241 SmallVector<const SCEV *, 16> RegSequence;
242
243public:
244 void countRegister(const SCEV *Reg, size_t LUIdx);
245 void dropRegister(const SCEV *Reg, size_t LUIdx);
246 void swapAndDropUse(size_t LUIdx, size_t LastLUIdx);
247
248 bool isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const;
249
250 const SmallBitVector &getUsedByIndices(const SCEV *Reg) const;
251
252 void clear();
253
254 using iterator = SmallVectorImpl<const SCEV *>::iterator;
255 using const_iterator = SmallVectorImpl<const SCEV *>::const_iterator;
256
257 iterator begin() { return RegSequence.begin(); }
258 iterator end() { return RegSequence.end(); }
259 const_iterator begin() const { return RegSequence.begin(); }
260 const_iterator end() const { return RegSequence.end(); }
261};
262
263} // end anonymous namespace
264
265void
266RegUseTracker::countRegister(const SCEV *Reg, size_t LUIdx) {
267 std::pair<RegUsesTy::iterator, bool> Pair =
268 RegUsesMap.insert(std::make_pair(Reg, RegSortData()));
269 RegSortData &RSD = Pair.first->second;
270 if (Pair.second)
271 RegSequence.push_back(Reg);
272 RSD.UsedByIndices.resize(std::max(RSD.UsedByIndices.size(), LUIdx + 1));
273 RSD.UsedByIndices.set(LUIdx);
274}
275
276void
277RegUseTracker::dropRegister(const SCEV *Reg, size_t LUIdx) {
278 RegUsesTy::iterator It = RegUsesMap.find(Reg);
279 assert(It != RegUsesMap.end())((It != RegUsesMap.end()) ? static_cast<void> (0) : __assert_fail
("It != RegUsesMap.end()", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 279, __PRETTY_FUNCTION__))
;
280 RegSortData &RSD = It->second;
281 assert(RSD.UsedByIndices.size() > LUIdx)((RSD.UsedByIndices.size() > LUIdx) ? static_cast<void>
(0) : __assert_fail ("RSD.UsedByIndices.size() > LUIdx", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 281, __PRETTY_FUNCTION__))
;
282 RSD.UsedByIndices.reset(LUIdx);
283}
284
285void
286RegUseTracker::swapAndDropUse(size_t LUIdx, size_t LastLUIdx) {
287 assert(LUIdx <= LastLUIdx)((LUIdx <= LastLUIdx) ? static_cast<void> (0) : __assert_fail
("LUIdx <= LastLUIdx", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 287, __PRETTY_FUNCTION__))
;
288
289 // Update RegUses. The data structure is not optimized for this purpose;
290 // we must iterate through it and update each of the bit vectors.
291 for (auto &Pair : RegUsesMap) {
292 SmallBitVector &UsedByIndices = Pair.second.UsedByIndices;
293 if (LUIdx < UsedByIndices.size())
294 UsedByIndices[LUIdx] =
295 LastLUIdx < UsedByIndices.size() ? UsedByIndices[LastLUIdx] : false;
296 UsedByIndices.resize(std::min(UsedByIndices.size(), LastLUIdx));
297 }
298}
299
300bool
301RegUseTracker::isRegUsedByUsesOtherThan(const SCEV *Reg, size_t LUIdx) const {
302 RegUsesTy::const_iterator I = RegUsesMap.find(Reg);
303 if (I == RegUsesMap.end())
304 return false;
305 const SmallBitVector &UsedByIndices = I->second.UsedByIndices;
306 int i = UsedByIndices.find_first();
307 if (i == -1) return false;
308 if ((size_t)i != LUIdx) return true;
309 return UsedByIndices.find_next(i) != -1;
310}
311
312const SmallBitVector &RegUseTracker::getUsedByIndices(const SCEV *Reg) const {
313 RegUsesTy::const_iterator I = RegUsesMap.find(Reg);
314 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 314, __PRETTY_FUNCTION__))
;
315 return I->second.UsedByIndices;
316}
317
318void RegUseTracker::clear() {
319 RegUsesMap.clear();
320 RegSequence.clear();
321}
322
323namespace {
324
325/// This class holds information that describes a formula for computing
326/// satisfying a use. It may include broken-out immediates and scaled registers.
327struct Formula {
328 /// Global base address used for complex addressing.
329 GlobalValue *BaseGV = nullptr;
330
331 /// Base offset for complex addressing.
332 int64_t BaseOffset = 0;
333
334 /// Whether any complex addressing has a base register.
335 bool HasBaseReg = false;
336
337 /// The scale of any complex addressing.
338 int64_t Scale = 0;
339
340 /// The list of "base" registers for this use. When this is non-empty. The
341 /// canonical representation of a formula is
342 /// 1. BaseRegs.size > 1 implies ScaledReg != NULL and
343 /// 2. ScaledReg != NULL implies Scale != 1 || !BaseRegs.empty().
344 /// 3. The reg containing recurrent expr related with currect loop in the
345 /// formula should be put in the ScaledReg.
346 /// #1 enforces that the scaled register is always used when at least two
347 /// registers are needed by the formula: e.g., reg1 + reg2 is reg1 + 1 * reg2.
348 /// #2 enforces that 1 * reg is reg.
349 /// #3 ensures invariant regs with respect to current loop can be combined
350 /// together in LSR codegen.
351 /// This invariant can be temporarily broken while building a formula.
352 /// However, every formula inserted into the LSRInstance must be in canonical
353 /// form.
354 SmallVector<const SCEV *, 4> BaseRegs;
355
356 /// The 'scaled' register for this use. This should be non-null when Scale is
357 /// not zero.
358 const SCEV *ScaledReg = nullptr;
359
360 /// An additional constant offset which added near the use. This requires a
361 /// temporary register, but the offset itself can live in an add immediate
362 /// field rather than a register.
363 int64_t UnfoldedOffset = 0;
364
365 Formula() = default;
366
367 void initialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE);
368
369 bool isCanonical(const Loop &L) const;
370
371 void canonicalize(const Loop &L);
372
373 bool unscale();
374
375 bool hasZeroEnd() const;
376
377 size_t getNumRegs() const;
378 Type *getType() const;
379
380 void deleteBaseReg(const SCEV *&S);
381
382 bool referencesReg(const SCEV *S) const;
383 bool hasRegsUsedByUsesOtherThan(size_t LUIdx,
384 const RegUseTracker &RegUses) const;
385
386 void print(raw_ostream &OS) const;
387 void dump() const;
388};
389
390} // end anonymous namespace
391
392/// Recursion helper for initialMatch.
393static void DoInitialMatch(const SCEV *S, Loop *L,
394 SmallVectorImpl<const SCEV *> &Good,
395 SmallVectorImpl<const SCEV *> &Bad,
396 ScalarEvolution &SE) {
397 // Collect expressions which properly dominate the loop header.
398 if (SE.properlyDominates(S, L->getHeader())) {
399 Good.push_back(S);
400 return;
401 }
402
403 // Look at add operands.
404 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
405 for (const SCEV *S : Add->operands())
406 DoInitialMatch(S, L, Good, Bad, SE);
407 return;
408 }
409
410 // Look at addrec operands.
411 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S))
412 if (!AR->getStart()->isZero() && AR->isAffine()) {
413 DoInitialMatch(AR->getStart(), L, Good, Bad, SE);
414 DoInitialMatch(SE.getAddRecExpr(SE.getConstant(AR->getType(), 0),
415 AR->getStepRecurrence(SE),
416 // FIXME: AR->getNoWrapFlags()
417 AR->getLoop(), SCEV::FlagAnyWrap),
418 L, Good, Bad, SE);
419 return;
420 }
421
422 // Handle a multiplication by -1 (negation) if it didn't fold.
423 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S))
424 if (Mul->getOperand(0)->isAllOnesValue()) {
425 SmallVector<const SCEV *, 4> Ops(Mul->op_begin()+1, Mul->op_end());
426 const SCEV *NewMul = SE.getMulExpr(Ops);
427
428 SmallVector<const SCEV *, 4> MyGood;
429 SmallVector<const SCEV *, 4> MyBad;
430 DoInitialMatch(NewMul, L, MyGood, MyBad, SE);
431 const SCEV *NegOne = SE.getSCEV(ConstantInt::getAllOnesValue(
432 SE.getEffectiveSCEVType(NewMul->getType())));
433 for (const SCEV *S : MyGood)
434 Good.push_back(SE.getMulExpr(NegOne, S));
435 for (const SCEV *S : MyBad)
436 Bad.push_back(SE.getMulExpr(NegOne, S));
437 return;
438 }
439
440 // Ok, we can't do anything interesting. Just stuff the whole thing into a
441 // register and hope for the best.
442 Bad.push_back(S);
443}
444
445/// Incorporate loop-variant parts of S into this Formula, attempting to keep
446/// all loop-invariant and loop-computable values in a single base register.
447void Formula::initialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE) {
448 SmallVector<const SCEV *, 4> Good;
449 SmallVector<const SCEV *, 4> Bad;
450 DoInitialMatch(S, L, Good, Bad, SE);
451 if (!Good.empty()) {
452 const SCEV *Sum = SE.getAddExpr(Good);
453 if (!Sum->isZero())
454 BaseRegs.push_back(Sum);
455 HasBaseReg = true;
456 }
457 if (!Bad.empty()) {
458 const SCEV *Sum = SE.getAddExpr(Bad);
459 if (!Sum->isZero())
460 BaseRegs.push_back(Sum);
461 HasBaseReg = true;
462 }
463 canonicalize(*L);
464}
465
466/// Check whether or not this formula satisfies the canonical
467/// representation.
468/// \see Formula::BaseRegs.
469bool Formula::isCanonical(const Loop &L) const {
470 if (!ScaledReg)
471 return BaseRegs.size() <= 1;
472
473 if (Scale != 1)
474 return true;
475
476 if (Scale == 1 && BaseRegs.empty())
477 return false;
478
479 const SCEVAddRecExpr *SAR = dyn_cast<const SCEVAddRecExpr>(ScaledReg);
480 if (SAR && SAR->getLoop() == &L)
481 return true;
482
483 // If ScaledReg is not a recurrent expr, or it is but its loop is not current
484 // loop, meanwhile BaseRegs contains a recurrent expr reg related with current
485 // loop, we want to swap the reg in BaseRegs with ScaledReg.
486 auto I =
487 find_if(make_range(BaseRegs.begin(), BaseRegs.end()), [&](const SCEV *S) {
488 return isa<const SCEVAddRecExpr>(S) &&
489 (cast<SCEVAddRecExpr>(S)->getLoop() == &L);
490 });
491 return I == BaseRegs.end();
492}
493
494/// Helper method to morph a formula into its canonical representation.
495/// \see Formula::BaseRegs.
496/// Every formula having more than one base register, must use the ScaledReg
497/// field. Otherwise, we would have to do special cases everywhere in LSR
498/// to treat reg1 + reg2 + ... the same way as reg1 + 1*reg2 + ...
499/// On the other hand, 1*reg should be canonicalized into reg.
500void Formula::canonicalize(const Loop &L) {
501 if (isCanonical(L))
502 return;
503 // So far we did not need this case. This is easy to implement but it is
504 // useless to maintain dead code. Beside it could hurt compile time.
505 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 505, __PRETTY_FUNCTION__))
;
506
507 // Keep the invariant sum in BaseRegs and one of the variant sum in ScaledReg.
508 if (!ScaledReg) {
509 ScaledReg = BaseRegs.back();
510 BaseRegs.pop_back();
511 Scale = 1;
512 }
513
514 // If ScaledReg is an invariant with respect to L, find the reg from
515 // BaseRegs containing the recurrent expr related with Loop L. Swap the
516 // reg with ScaledReg.
517 const SCEVAddRecExpr *SAR = dyn_cast<const SCEVAddRecExpr>(ScaledReg);
518 if (!SAR || SAR->getLoop() != &L) {
519 auto I = find_if(make_range(BaseRegs.begin(), BaseRegs.end()),
520 [&](const SCEV *S) {
521 return isa<const SCEVAddRecExpr>(S) &&
522 (cast<SCEVAddRecExpr>(S)->getLoop() == &L);
523 });
524 if (I != BaseRegs.end())
525 std::swap(ScaledReg, *I);
526 }
527}
528
529/// Get rid of the scale in the formula.
530/// In other words, this method morphes reg1 + 1*reg2 into reg1 + reg2.
531/// \return true if it was possible to get rid of the scale, false otherwise.
532/// \note After this operation the formula may not be in the canonical form.
533bool Formula::unscale() {
534 if (Scale != 1)
535 return false;
536 Scale = 0;
537 BaseRegs.push_back(ScaledReg);
538 ScaledReg = nullptr;
539 return true;
540}
541
542bool Formula::hasZeroEnd() const {
543 if (UnfoldedOffset || BaseOffset)
544 return false;
545 if (BaseRegs.size() != 1 || ScaledReg)
546 return false;
547 return true;
548}
549
550/// Return the total number of register operands used by this formula. This does
551/// not include register uses implied by non-constant addrec strides.
552size_t Formula::getNumRegs() const {
553 return !!ScaledReg + BaseRegs.size();
554}
555
556/// Return the type of this formula, if it has one, or null otherwise. This type
557/// is meaningless except for the bit size.
558Type *Formula::getType() const {
559 return !BaseRegs.empty() ? BaseRegs.front()->getType() :
560 ScaledReg ? ScaledReg->getType() :
561 BaseGV ? BaseGV->getType() :
562 nullptr;
563}
564
565/// Delete the given base reg from the BaseRegs list.
566void Formula::deleteBaseReg(const SCEV *&S) {
567 if (&S != &BaseRegs.back())
568 std::swap(S, BaseRegs.back());
569 BaseRegs.pop_back();
570}
571
572/// Test if this formula references the given register.
573bool Formula::referencesReg(const SCEV *S) const {
574 return S == ScaledReg || is_contained(BaseRegs, S);
575}
576
577/// Test whether this formula uses registers which are used by uses other than
578/// the use with the given index.
579bool Formula::hasRegsUsedByUsesOtherThan(size_t LUIdx,
580 const RegUseTracker &RegUses) const {
581 if (ScaledReg)
582 if (RegUses.isRegUsedByUsesOtherThan(ScaledReg, LUIdx))
583 return true;
584 for (const SCEV *BaseReg : BaseRegs)
585 if (RegUses.isRegUsedByUsesOtherThan(BaseReg, LUIdx))
586 return true;
587 return false;
588}
589
590#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
591void Formula::print(raw_ostream &OS) const {
592 bool First = true;
593 if (BaseGV) {
594 if (!First) OS << " + "; else First = false;
595 BaseGV->printAsOperand(OS, /*PrintType=*/false);
596 }
597 if (BaseOffset != 0) {
598 if (!First) OS << " + "; else First = false;
599 OS << BaseOffset;
600 }
601 for (const SCEV *BaseReg : BaseRegs) {
602 if (!First) OS << " + "; else First = false;
603 OS << "reg(" << *BaseReg << ')';
604 }
605 if (HasBaseReg && BaseRegs.empty()) {
606 if (!First) OS << " + "; else First = false;
607 OS << "**error: HasBaseReg**";
608 } else if (!HasBaseReg && !BaseRegs.empty()) {
609 if (!First) OS << " + "; else First = false;
610 OS << "**error: !HasBaseReg**";
611 }
612 if (Scale != 0) {
613 if (!First) OS << " + "; else First = false;
614 OS << Scale << "*reg(";
615 if (ScaledReg)
616 OS << *ScaledReg;
617 else
618 OS << "<unknown>";
619 OS << ')';
620 }
621 if (UnfoldedOffset != 0) {
622 if (!First) OS << " + ";
623 OS << "imm(" << UnfoldedOffset << ')';
624 }
625}
626
627LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void Formula::dump() const {
628 print(errs()); errs() << '\n';
629}
630#endif
631
632/// Return true if the given addrec can be sign-extended without changing its
633/// value.
634static bool isAddRecSExtable(const SCEVAddRecExpr *AR, ScalarEvolution &SE) {
635 Type *WideTy =
636 IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(AR->getType()) + 1);
637 return isa<SCEVAddRecExpr>(SE.getSignExtendExpr(AR, WideTy));
638}
639
640/// Return true if the given add can be sign-extended without changing its
641/// value.
642static bool isAddSExtable(const SCEVAddExpr *A, ScalarEvolution &SE) {
643 Type *WideTy =
644 IntegerType::get(SE.getContext(), SE.getTypeSizeInBits(A->getType()) + 1);
645 return isa<SCEVAddExpr>(SE.getSignExtendExpr(A, WideTy));
646}
647
648/// Return true if the given mul can be sign-extended without changing its
649/// value.
650static bool isMulSExtable(const SCEVMulExpr *M, ScalarEvolution &SE) {
651 Type *WideTy =
652 IntegerType::get(SE.getContext(),
653 SE.getTypeSizeInBits(M->getType()) * M->getNumOperands());
654 return isa<SCEVMulExpr>(SE.getSignExtendExpr(M, WideTy));
655}
656
657/// Return an expression for LHS /s RHS, if it can be determined and if the
658/// remainder is known to be zero, or null otherwise. If IgnoreSignificantBits
659/// is true, expressions like (X * Y) /s Y are simplified to Y, ignoring that
660/// the multiplication may overflow, which is useful when the result will be
661/// used in a context where the most significant bits are ignored.
662static const SCEV *getExactSDiv(const SCEV *LHS, const SCEV *RHS,
663 ScalarEvolution &SE,
664 bool IgnoreSignificantBits = false) {
665 // Handle the trivial case, which works for any SCEV type.
666 if (LHS == RHS)
667 return SE.getConstant(LHS->getType(), 1);
668
669 // Handle a few RHS special cases.
670 const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS);
671 if (RC) {
672 const APInt &RA = RC->getAPInt();
673 // Handle x /s -1 as x * -1, to give ScalarEvolution a chance to do
674 // some folding.
675 if (RA.isAllOnesValue())
676 return SE.getMulExpr(LHS, RC);
677 // Handle x /s 1 as x.
678 if (RA == 1)
679 return LHS;
680 }
681
682 // Check for a division of a constant by a constant.
683 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(LHS)) {
684 if (!RC)
685 return nullptr;
686 const APInt &LA = C->getAPInt();
687 const APInt &RA = RC->getAPInt();
688 if (LA.srem(RA) != 0)
689 return nullptr;
690 return SE.getConstant(LA.sdiv(RA));
691 }
692
693 // Distribute the sdiv over addrec operands, if the addrec doesn't overflow.
694 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) {
695 if ((IgnoreSignificantBits || isAddRecSExtable(AR, SE)) && AR->isAffine()) {
696 const SCEV *Step = getExactSDiv(AR->getStepRecurrence(SE), RHS, SE,
697 IgnoreSignificantBits);
698 if (!Step) return nullptr;
699 const SCEV *Start = getExactSDiv(AR->getStart(), RHS, SE,
700 IgnoreSignificantBits);
701 if (!Start) return nullptr;
702 // FlagNW is independent of the start value, step direction, and is
703 // preserved with smaller magnitude steps.
704 // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
705 return SE.getAddRecExpr(Start, Step, AR->getLoop(), SCEV::FlagAnyWrap);
706 }
707 return nullptr;
708 }
709
710 // Distribute the sdiv over add operands, if the add doesn't overflow.
711 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(LHS)) {
712 if (IgnoreSignificantBits || isAddSExtable(Add, SE)) {
713 SmallVector<const SCEV *, 8> Ops;
714 for (const SCEV *S : Add->operands()) {
715 const SCEV *Op = getExactSDiv(S, RHS, SE, IgnoreSignificantBits);
716 if (!Op) return nullptr;
717 Ops.push_back(Op);
718 }
719 return SE.getAddExpr(Ops);
720 }
721 return nullptr;
722 }
723
724 // Check for a multiply operand that we can pull RHS out of.
725 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS)) {
726 if (IgnoreSignificantBits || isMulSExtable(Mul, SE)) {
727 SmallVector<const SCEV *, 4> Ops;
728 bool Found = false;
729 for (const SCEV *S : Mul->operands()) {
730 if (!Found)
731 if (const SCEV *Q = getExactSDiv(S, RHS, SE,
732 IgnoreSignificantBits)) {
733 S = Q;
734 Found = true;
735 }
736 Ops.push_back(S);
737 }
738 return Found ? SE.getMulExpr(Ops) : nullptr;
739 }
740 return nullptr;
741 }
742
743 // Otherwise we don't know.
744 return nullptr;
745}
746
747/// If S involves the addition of a constant integer value, return that integer
748/// value, and mutate S to point to a new SCEV with that value excluded.
749static int64_t ExtractImmediate(const SCEV *&S, ScalarEvolution &SE) {
750 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
751 if (C->getAPInt().getMinSignedBits() <= 64) {
752 S = SE.getConstant(C->getType(), 0);
753 return C->getValue()->getSExtValue();
754 }
755 } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
756 SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());
757 int64_t Result = ExtractImmediate(NewOps.front(), SE);
758 if (Result != 0)
759 S = SE.getAddExpr(NewOps);
760 return Result;
761 } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
762 SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
763 int64_t Result = ExtractImmediate(NewOps.front(), SE);
764 if (Result != 0)
765 S = SE.getAddRecExpr(NewOps, AR->getLoop(),
766 // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
767 SCEV::FlagAnyWrap);
768 return Result;
769 }
770 return 0;
771}
772
773/// If S involves the addition of a GlobalValue address, return that symbol, and
774/// mutate S to point to a new SCEV with that value excluded.
775static GlobalValue *ExtractSymbol(const SCEV *&S, ScalarEvolution &SE) {
776 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
777 if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue())) {
778 S = SE.getConstant(GV->getType(), 0);
779 return GV;
780 }
781 } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
782 SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());
783 GlobalValue *Result = ExtractSymbol(NewOps.back(), SE);
784 if (Result)
785 S = SE.getAddExpr(NewOps);
786 return Result;
787 } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
788 SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
789 GlobalValue *Result = ExtractSymbol(NewOps.front(), SE);
790 if (Result)
791 S = SE.getAddRecExpr(NewOps, AR->getLoop(),
792 // FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
793 SCEV::FlagAnyWrap);
794 return Result;
795 }
796 return nullptr;
797}
798
799/// Returns true if the specified instruction is using the specified value as an
800/// address.
801static bool isAddressUse(const TargetTransformInfo &TTI,
802 Instruction *Inst, Value *OperandVal) {
803 bool isAddress = isa<LoadInst>(Inst);
804 if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
805 if (SI->getPointerOperand() == OperandVal)
806 isAddress = true;
807 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
808 // Addressing modes can also be folded into prefetches and a variety
809 // of intrinsics.
810 switch (II->getIntrinsicID()) {
811 case Intrinsic::memset:
812 case Intrinsic::prefetch:
813 case Intrinsic::masked_load:
814 if (II->getArgOperand(0) == OperandVal)
815 isAddress = true;
816 break;
817 case Intrinsic::masked_store:
818 if (II->getArgOperand(1) == OperandVal)
819 isAddress = true;
820 break;
821 case Intrinsic::memmove:
822 case Intrinsic::memcpy:
823 if (II->getArgOperand(0) == OperandVal ||
824 II->getArgOperand(1) == OperandVal)
825 isAddress = true;
826 break;
827 default: {
828 MemIntrinsicInfo IntrInfo;
829 if (TTI.getTgtMemIntrinsic(II, IntrInfo)) {
830 if (IntrInfo.PtrVal == OperandVal)
831 isAddress = true;
832 }
833 }
834 }
835 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(Inst)) {
836 if (RMW->getPointerOperand() == OperandVal)
837 isAddress = true;
838 } else if (AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(Inst)) {
839 if (CmpX->getPointerOperand() == OperandVal)
840 isAddress = true;
841 }
842 return isAddress;
843}
844
845/// Return the type of the memory being accessed.
846static MemAccessTy getAccessType(const TargetTransformInfo &TTI,
847 Instruction *Inst, Value *OperandVal) {
848 MemAccessTy AccessTy(Inst->getType(), MemAccessTy::UnknownAddressSpace);
849 if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
850 AccessTy.MemTy = SI->getOperand(0)->getType();
851 AccessTy.AddrSpace = SI->getPointerAddressSpace();
852 } else if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
853 AccessTy.AddrSpace = LI->getPointerAddressSpace();
854 } else if (const AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(Inst)) {
855 AccessTy.AddrSpace = RMW->getPointerAddressSpace();
856 } else if (const AtomicCmpXchgInst *CmpX = dyn_cast<AtomicCmpXchgInst>(Inst)) {
857 AccessTy.AddrSpace = CmpX->getPointerAddressSpace();
858 } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
859 switch (II->getIntrinsicID()) {
860 case Intrinsic::prefetch:
861 case Intrinsic::memset:
862 AccessTy.AddrSpace = II->getArgOperand(0)->getType()->getPointerAddressSpace();
863 AccessTy.MemTy = OperandVal->getType();
864 break;
865 case Intrinsic::memmove:
866 case Intrinsic::memcpy:
867 AccessTy.AddrSpace = OperandVal->getType()->getPointerAddressSpace();
868 AccessTy.MemTy = OperandVal->getType();
869 break;
870 case Intrinsic::masked_load:
871 AccessTy.AddrSpace =
872 II->getArgOperand(0)->getType()->getPointerAddressSpace();
873 break;
874 case Intrinsic::masked_store:
875 AccessTy.MemTy = II->getOperand(0)->getType();
876 AccessTy.AddrSpace =
877 II->getArgOperand(1)->getType()->getPointerAddressSpace();
878 break;
879 default: {
880 MemIntrinsicInfo IntrInfo;
881 if (TTI.getTgtMemIntrinsic(II, IntrInfo) && IntrInfo.PtrVal) {
882 AccessTy.AddrSpace
883 = IntrInfo.PtrVal->getType()->getPointerAddressSpace();
884 }
885
886 break;
887 }
888 }
889 }
890
891 // All pointers have the same requirements, so canonicalize them to an
892 // arbitrary pointer type to minimize variation.
893 if (PointerType *PTy = dyn_cast<PointerType>(AccessTy.MemTy))
894 AccessTy.MemTy = PointerType::get(IntegerType::get(PTy->getContext(), 1),
895 PTy->getAddressSpace());
896
897 return AccessTy;
898}
899
900/// Return true if this AddRec is already a phi in its loop.
901static bool isExistingPhi(const SCEVAddRecExpr *AR, ScalarEvolution &SE) {
902 for (PHINode &PN : AR->getLoop()->getHeader()->phis()) {
903 if (SE.isSCEVable(PN.getType()) &&
904 (SE.getEffectiveSCEVType(PN.getType()) ==
905 SE.getEffectiveSCEVType(AR->getType())) &&
906 SE.getSCEV(&PN) == AR)
907 return true;
908 }
909 return false;
910}
911
912/// Check if expanding this expression is likely to incur significant cost. This
913/// is tricky because SCEV doesn't track which expressions are actually computed
914/// by the current IR.
915///
916/// We currently allow expansion of IV increments that involve adds,
917/// multiplication by constants, and AddRecs from existing phis.
918///
919/// TODO: Allow UDivExpr if we can find an existing IV increment that is an
920/// obvious multiple of the UDivExpr.
921static bool isHighCostExpansion(const SCEV *S,
922 SmallPtrSetImpl<const SCEV*> &Processed,
923 ScalarEvolution &SE) {
924 // Zero/One operand expressions
925 switch (S->getSCEVType()) {
926 case scUnknown:
927 case scConstant:
928 return false;
929 case scTruncate:
930 return isHighCostExpansion(cast<SCEVTruncateExpr>(S)->getOperand(),
931 Processed, SE);
932 case scZeroExtend:
933 return isHighCostExpansion(cast<SCEVZeroExtendExpr>(S)->getOperand(),
934 Processed, SE);
935 case scSignExtend:
936 return isHighCostExpansion(cast<SCEVSignExtendExpr>(S)->getOperand(),
937 Processed, SE);
938 }
939
940 if (!Processed.insert(S).second)
941 return false;
942
943 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
944 for (const SCEV *S : Add->operands()) {
945 if (isHighCostExpansion(S, Processed, SE))
946 return true;
947 }
948 return false;
949 }
950
951 if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
952 if (Mul->getNumOperands() == 2) {
953 // Multiplication by a constant is ok
954 if (isa<SCEVConstant>(Mul->getOperand(0)))
955 return isHighCostExpansion(Mul->getOperand(1), Processed, SE);
956
957 // If we have the value of one operand, check if an existing
958 // multiplication already generates this expression.
959 if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Mul->getOperand(1))) {
960 Value *UVal = U->getValue();
961 for (User *UR : UVal->users()) {
962 // If U is a constant, it may be used by a ConstantExpr.
963 Instruction *UI = dyn_cast<Instruction>(UR);
964 if (UI && UI->getOpcode() == Instruction::Mul &&
965 SE.isSCEVable(UI->getType())) {
966 return SE.getSCEV(UI) == Mul;
967 }
968 }
969 }
970 }
971 }
972
973 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
974 if (isExistingPhi(AR, SE))
975 return false;
976 }
977
978 // Fow now, consider any other type of expression (div/mul/min/max) high cost.
979 return true;
980}
981
982namespace {
983
984class LSRUse;
985
986} // end anonymous namespace
987
988/// Check if the addressing mode defined by \p F is completely
989/// folded in \p LU at isel time.
990/// This includes address-mode folding and special icmp tricks.
991/// This function returns true if \p LU can accommodate what \p F
992/// defines and up to 1 base + 1 scaled + offset.
993/// In other words, if \p F has several base registers, this function may
994/// still return true. Therefore, users still need to account for
995/// additional base registers and/or unfolded offsets to derive an
996/// accurate cost model.
997static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
998 const LSRUse &LU, const Formula &F);
999
1000// Get the cost of the scaling factor used in F for LU.
1001static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,
1002 const LSRUse &LU, const Formula &F,
1003 const Loop &L);
1004
1005namespace {
1006
1007/// This class is used to measure and compare candidate formulae.
1008class Cost {
1009 const Loop *L = nullptr;
1010 ScalarEvolution *SE = nullptr;
1011 const TargetTransformInfo *TTI = nullptr;
1012 TargetTransformInfo::LSRCost C;
1013
1014public:
1015 Cost() = delete;
1016 Cost(const Loop *L, ScalarEvolution &SE, const TargetTransformInfo &TTI) :
1017 L(L), SE(&SE), TTI(&TTI) {
1018 C.Insns = 0;
1019 C.NumRegs = 0;
1020 C.AddRecCost = 0;
1021 C.NumIVMuls = 0;
1022 C.NumBaseAdds = 0;
1023 C.ImmCost = 0;
1024 C.SetupCost = 0;
1025 C.ScaleCost = 0;
1026 }
1027
1028 bool isLess(Cost &Other);
1029
1030 void Lose();
1031
1032#ifndef NDEBUG
1033 // Once any of the metrics loses, they must all remain losers.
1034 bool isValid() {
1035 return ((C.Insns | C.NumRegs | C.AddRecCost | C.NumIVMuls | C.NumBaseAdds
1036 | C.ImmCost | C.SetupCost | C.ScaleCost) != ~0u)
1037 || ((C.Insns & C.NumRegs & C.AddRecCost & C.NumIVMuls & C.NumBaseAdds
1038 & C.ImmCost & C.SetupCost & C.ScaleCost) == ~0u);
1039 }
1040#endif
1041
1042 bool isLoser() {
1043 assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void>
(0) : __assert_fail ("isValid() && \"invalid cost\""
, "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1043, __PRETTY_FUNCTION__))
;
1044 return C.NumRegs == ~0u;
1045 }
1046
1047 void RateFormula(const Formula &F,
1048 SmallPtrSetImpl<const SCEV *> &Regs,
1049 const DenseSet<const SCEV *> &VisitedRegs,
1050 const LSRUse &LU,
1051 SmallPtrSetImpl<const SCEV *> *LoserRegs = nullptr);
1052
1053 void print(raw_ostream &OS) const;
1054 void dump() const;
1055
1056private:
1057 void RateRegister(const Formula &F, const SCEV *Reg,
1058 SmallPtrSetImpl<const SCEV *> &Regs);
1059 void RatePrimaryRegister(const Formula &F, const SCEV *Reg,
1060 SmallPtrSetImpl<const SCEV *> &Regs,
1061 SmallPtrSetImpl<const SCEV *> *LoserRegs);
1062};
1063
1064/// An operand value in an instruction which is to be replaced with some
1065/// equivalent, possibly strength-reduced, replacement.
1066struct LSRFixup {
1067 /// The instruction which will be updated.
1068 Instruction *UserInst = nullptr;
1069
1070 /// The operand of the instruction which will be replaced. The operand may be
1071 /// used more than once; every instance will be replaced.
1072 Value *OperandValToReplace = nullptr;
1073
1074 /// If this user is to use the post-incremented value of an induction
1075 /// variable, this set is non-empty and holds the loops associated with the
1076 /// induction variable.
1077 PostIncLoopSet PostIncLoops;
1078
1079 /// A constant offset to be added to the LSRUse expression. This allows
1080 /// multiple fixups to share the same LSRUse with different offsets, for
1081 /// example in an unrolled loop.
1082 int64_t Offset = 0;
1083
1084 LSRFixup() = default;
1085
1086 bool isUseFullyOutsideLoop(const Loop *L) const;
1087
1088 void print(raw_ostream &OS) const;
1089 void dump() const;
1090};
1091
1092/// A DenseMapInfo implementation for holding DenseMaps and DenseSets of sorted
1093/// SmallVectors of const SCEV*.
1094struct UniquifierDenseMapInfo {
1095 static SmallVector<const SCEV *, 4> getEmptyKey() {
1096 SmallVector<const SCEV *, 4> V;
1097 V.push_back(reinterpret_cast<const SCEV *>(-1));
1098 return V;
1099 }
1100
1101 static SmallVector<const SCEV *, 4> getTombstoneKey() {
1102 SmallVector<const SCEV *, 4> V;
1103 V.push_back(reinterpret_cast<const SCEV *>(-2));
1104 return V;
1105 }
1106
1107 static unsigned getHashValue(const SmallVector<const SCEV *, 4> &V) {
1108 return static_cast<unsigned>(hash_combine_range(V.begin(), V.end()));
1109 }
1110
1111 static bool isEqual(const SmallVector<const SCEV *, 4> &LHS,
1112 const SmallVector<const SCEV *, 4> &RHS) {
1113 return LHS == RHS;
1114 }
1115};
1116
1117/// This class holds the state that LSR keeps for each use in IVUsers, as well
1118/// as uses invented by LSR itself. It includes information about what kinds of
1119/// things can be folded into the user, information about the user itself, and
1120/// information about how the use may be satisfied. TODO: Represent multiple
1121/// users of the same expression in common?
1122class LSRUse {
1123 DenseSet<SmallVector<const SCEV *, 4>, UniquifierDenseMapInfo> Uniquifier;
1124
1125public:
1126 /// An enum for a kind of use, indicating what types of scaled and immediate
1127 /// operands it might support.
1128 enum KindType {
1129 Basic, ///< A normal use, with no folding.
1130 Special, ///< A special case of basic, allowing -1 scales.
1131 Address, ///< An address use; folding according to TargetLowering
1132 ICmpZero ///< An equality icmp with both operands folded into one.
1133 // TODO: Add a generic icmp too?
1134 };
1135
1136 using SCEVUseKindPair = PointerIntPair<const SCEV *, 2, KindType>;
1137
1138 KindType Kind;
1139 MemAccessTy AccessTy;
1140
1141 /// The list of operands which are to be replaced.
1142 SmallVector<LSRFixup, 8> Fixups;
1143
1144 /// Keep track of the min and max offsets of the fixups.
1145 int64_t MinOffset = std::numeric_limits<int64_t>::max();
1146 int64_t MaxOffset = std::numeric_limits<int64_t>::min();
1147
1148 /// This records whether all of the fixups using this LSRUse are outside of
1149 /// the loop, in which case some special-case heuristics may be used.
1150 bool AllFixupsOutsideLoop = true;
1151
1152 /// RigidFormula is set to true to guarantee that this use will be associated
1153 /// with a single formula--the one that initially matched. Some SCEV
1154 /// expressions cannot be expanded. This allows LSR to consider the registers
1155 /// used by those expressions without the need to expand them later after
1156 /// changing the formula.
1157 bool RigidFormula = false;
1158
1159 /// This records the widest use type for any fixup using this
1160 /// LSRUse. FindUseWithSimilarFormula can't consider uses with different max
1161 /// fixup widths to be equivalent, because the narrower one may be relying on
1162 /// the implicit truncation to truncate away bogus bits.
1163 Type *WidestFixupType = nullptr;
1164
1165 /// A list of ways to build a value that can satisfy this user. After the
1166 /// list is populated, one of these is selected heuristically and used to
1167 /// formulate a replacement for OperandValToReplace in UserInst.
1168 SmallVector<Formula, 12> Formulae;
1169
1170 /// The set of register candidates used by all formulae in this LSRUse.
1171 SmallPtrSet<const SCEV *, 4> Regs;
1172
1173 LSRUse(KindType K, MemAccessTy AT) : Kind(K), AccessTy(AT) {}
1174
1175 LSRFixup &getNewFixup() {
1176 Fixups.push_back(LSRFixup());
1177 return Fixups.back();
1178 }
1179
1180 void pushFixup(LSRFixup &f) {
1181 Fixups.push_back(f);
1182 if (f.Offset > MaxOffset)
1183 MaxOffset = f.Offset;
1184 if (f.Offset < MinOffset)
1185 MinOffset = f.Offset;
1186 }
1187
1188 bool HasFormulaWithSameRegs(const Formula &F) const;
1189 float getNotSelectedProbability(const SCEV *Reg) const;
1190 bool InsertFormula(const Formula &F, const Loop &L);
1191 void DeleteFormula(Formula &F);
1192 void RecomputeRegs(size_t LUIdx, RegUseTracker &Reguses);
1193
1194 void print(raw_ostream &OS) const;
1195 void dump() const;
1196};
1197
1198} // end anonymous namespace
1199
1200static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1201 LSRUse::KindType Kind, MemAccessTy AccessTy,
1202 GlobalValue *BaseGV, int64_t BaseOffset,
1203 bool HasBaseReg, int64_t Scale,
1204 Instruction *Fixup = nullptr);
1205
1206static unsigned getSetupCost(const SCEV *Reg, unsigned Depth) {
1207 if (isa<SCEVUnknown>(Reg) || isa<SCEVConstant>(Reg))
1208 return 1;
1209 if (Depth == 0)
1210 return 0;
1211 if (const auto *S = dyn_cast<SCEVAddRecExpr>(Reg))
1212 return getSetupCost(S->getStart(), Depth - 1);
1213 if (auto S = dyn_cast<SCEVCastExpr>(Reg))
1214 return getSetupCost(S->getOperand(), Depth - 1);
1215 if (auto S = dyn_cast<SCEVNAryExpr>(Reg))
1216 return std::accumulate(S->op_begin(), S->op_end(), 0,
1217 [&](unsigned i, const SCEV *Reg) {
1218 return i + getSetupCost(Reg, Depth - 1);
1219 });
1220 if (auto S = dyn_cast<SCEVUDivExpr>(Reg))
1221 return getSetupCost(S->getLHS(), Depth - 1) +
1222 getSetupCost(S->getRHS(), Depth - 1);
1223 return 0;
1224}
1225
1226/// Tally up interesting quantities from the given register.
1227void Cost::RateRegister(const Formula &F, const SCEV *Reg,
1228 SmallPtrSetImpl<const SCEV *> &Regs) {
1229 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Reg)) {
1230 // If this is an addrec for another loop, it should be an invariant
1231 // with respect to L since L is the innermost loop (at least
1232 // for now LSR only handles innermost loops).
1233 if (AR->getLoop() != L) {
1234 // If the AddRec exists, consider it's register free and leave it alone.
1235 if (isExistingPhi(AR, *SE) && !TTI->shouldFavorPostInc())
1236 return;
1237
1238 // It is bad to allow LSR for current loop to add induction variables
1239 // for its sibling loops.
1240 if (!AR->getLoop()->contains(L)) {
1241 Lose();
1242 return;
1243 }
1244
1245 // Otherwise, it will be an invariant with respect to Loop L.
1246 ++C.NumRegs;
1247 return;
1248 }
1249
1250 unsigned LoopCost = 1;
1251 if (TTI->isIndexedLoadLegal(TTI->MIM_PostInc, AR->getType()) ||
1252 TTI->isIndexedStoreLegal(TTI->MIM_PostInc, AR->getType())) {
1253
1254 // If the step size matches the base offset, we could use pre-indexed
1255 // addressing.
1256 if (TTI->shouldFavorBackedgeIndex(L)) {
1257 if (auto *Step = dyn_cast<SCEVConstant>(AR->getStepRecurrence(*SE)))
1258 if (Step->getAPInt() == F.BaseOffset)
1259 LoopCost = 0;
1260 }
1261
1262 if (TTI->shouldFavorPostInc()) {
1263 const SCEV *LoopStep = AR->getStepRecurrence(*SE);
1264 if (isa<SCEVConstant>(LoopStep)) {
1265 const SCEV *LoopStart = AR->getStart();
1266 if (!isa<SCEVConstant>(LoopStart) &&
1267 SE->isLoopInvariant(LoopStart, L))
1268 LoopCost = 0;
1269 }
1270 }
1271 }
1272 C.AddRecCost += LoopCost;
1273
1274 // Add the step value register, if it needs one.
1275 // TODO: The non-affine case isn't precisely modeled here.
1276 if (!AR->isAffine() || !isa<SCEVConstant>(AR->getOperand(1))) {
1277 if (!Regs.count(AR->getOperand(1))) {
1278 RateRegister(F, AR->getOperand(1), Regs);
1279 if (isLoser())
1280 return;
1281 }
1282 }
1283 }
1284 ++C.NumRegs;
1285
1286 // Rough heuristic; favor registers which don't require extra setup
1287 // instructions in the preheader.
1288 C.SetupCost += getSetupCost(Reg, SetupCostDepthLimit);
1289 // Ensure we don't, even with the recusion limit, produce invalid costs.
1290 C.SetupCost = std::min<unsigned>(C.SetupCost, 1 << 16);
1291
1292 C.NumIVMuls += isa<SCEVMulExpr>(Reg) &&
1293 SE->hasComputableLoopEvolution(Reg, L);
1294}
1295
1296/// Record this register in the set. If we haven't seen it before, rate
1297/// it. Optional LoserRegs provides a way to declare any formula that refers to
1298/// one of those regs an instant loser.
1299void Cost::RatePrimaryRegister(const Formula &F, const SCEV *Reg,
1300 SmallPtrSetImpl<const SCEV *> &Regs,
1301 SmallPtrSetImpl<const SCEV *> *LoserRegs) {
1302 if (LoserRegs && LoserRegs->count(Reg)) {
1303 Lose();
1304 return;
1305 }
1306 if (Regs.insert(Reg).second) {
1307 RateRegister(F, Reg, Regs);
1308 if (LoserRegs && isLoser())
1309 LoserRegs->insert(Reg);
1310 }
1311}
1312
1313void Cost::RateFormula(const Formula &F,
1314 SmallPtrSetImpl<const SCEV *> &Regs,
1315 const DenseSet<const SCEV *> &VisitedRegs,
1316 const LSRUse &LU,
1317 SmallPtrSetImpl<const SCEV *> *LoserRegs) {
1318 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1318, __PRETTY_FUNCTION__))
;
1319 // Tally up the registers.
1320 unsigned PrevAddRecCost = C.AddRecCost;
1321 unsigned PrevNumRegs = C.NumRegs;
1322 unsigned PrevNumBaseAdds = C.NumBaseAdds;
1323 if (const SCEV *ScaledReg = F.ScaledReg) {
1324 if (VisitedRegs.count(ScaledReg)) {
1325 Lose();
1326 return;
1327 }
1328 RatePrimaryRegister(F, ScaledReg, Regs, LoserRegs);
1329 if (isLoser())
1330 return;
1331 }
1332 for (const SCEV *BaseReg : F.BaseRegs) {
1333 if (VisitedRegs.count(BaseReg)) {
1334 Lose();
1335 return;
1336 }
1337 RatePrimaryRegister(F, BaseReg, Regs, LoserRegs);
1338 if (isLoser())
1339 return;
1340 }
1341
1342 // Determine how many (unfolded) adds we'll need inside the loop.
1343 size_t NumBaseParts = F.getNumRegs();
1344 if (NumBaseParts > 1)
1345 // Do not count the base and a possible second register if the target
1346 // allows to fold 2 registers.
1347 C.NumBaseAdds +=
1348 NumBaseParts - (1 + (F.Scale && isAMCompletelyFolded(*TTI, LU, F)));
1349 C.NumBaseAdds += (F.UnfoldedOffset != 0);
1350
1351 // Accumulate non-free scaling amounts.
1352 C.ScaleCost += getScalingFactorCost(*TTI, LU, F, *L);
1353
1354 // Tally up the non-zero immediates.
1355 for (const LSRFixup &Fixup : LU.Fixups) {
1356 int64_t O = Fixup.Offset;
1357 int64_t Offset = (uint64_t)O + F.BaseOffset;
1358 if (F.BaseGV)
1359 C.ImmCost += 64; // Handle symbolic values conservatively.
1360 // TODO: This should probably be the pointer size.
1361 else if (Offset != 0)
1362 C.ImmCost += APInt(64, Offset, true).getMinSignedBits();
1363
1364 // Check with target if this offset with this instruction is
1365 // specifically not supported.
1366 if (LU.Kind == LSRUse::Address && Offset != 0 &&
1367 !isAMCompletelyFolded(*TTI, LSRUse::Address, LU.AccessTy, F.BaseGV,
1368 Offset, F.HasBaseReg, F.Scale, Fixup.UserInst))
1369 C.NumBaseAdds++;
1370 }
1371
1372 // If we don't count instruction cost exit here.
1373 if (!InsnsCost) {
1374 assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void>
(0) : __assert_fail ("isValid() && \"invalid cost\""
, "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1374, __PRETTY_FUNCTION__))
;
1375 return;
1376 }
1377
1378 // Treat every new register that exceeds TTI.getNumberOfRegisters() - 1 as
1379 // additional instruction (at least fill).
1380 // TODO: Need distinguish register class?
1381 unsigned TTIRegNum = TTI->getNumberOfRegisters(
1382 TTI->getRegisterClassForType(false, F.getType())) - 1;
1383 if (C.NumRegs > TTIRegNum) {
1384 // Cost already exceeded TTIRegNum, then only newly added register can add
1385 // new instructions.
1386 if (PrevNumRegs > TTIRegNum)
1387 C.Insns += (C.NumRegs - PrevNumRegs);
1388 else
1389 C.Insns += (C.NumRegs - TTIRegNum);
1390 }
1391
1392 // If ICmpZero formula ends with not 0, it could not be replaced by
1393 // just add or sub. We'll need to compare final result of AddRec.
1394 // That means we'll need an additional instruction. But if the target can
1395 // macro-fuse a compare with a branch, don't count this extra instruction.
1396 // For -10 + {0, +, 1}:
1397 // i = i + 1;
1398 // cmp i, 10
1399 //
1400 // For {-10, +, 1}:
1401 // i = i + 1;
1402 if (LU.Kind == LSRUse::ICmpZero && !F.hasZeroEnd() &&
1403 !TTI->canMacroFuseCmp())
1404 C.Insns++;
1405 // Each new AddRec adds 1 instruction to calculation.
1406 C.Insns += (C.AddRecCost - PrevAddRecCost);
1407
1408 // BaseAdds adds instructions for unfolded registers.
1409 if (LU.Kind != LSRUse::ICmpZero)
1410 C.Insns += C.NumBaseAdds - PrevNumBaseAdds;
1411 assert(isValid() && "invalid cost")((isValid() && "invalid cost") ? static_cast<void>
(0) : __assert_fail ("isValid() && \"invalid cost\""
, "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1411, __PRETTY_FUNCTION__))
;
1412}
1413
1414/// Set this cost to a losing value.
1415void Cost::Lose() {
1416 C.Insns = std::numeric_limits<unsigned>::max();
1417 C.NumRegs = std::numeric_limits<unsigned>::max();
1418 C.AddRecCost = std::numeric_limits<unsigned>::max();
1419 C.NumIVMuls = std::numeric_limits<unsigned>::max();
1420 C.NumBaseAdds = std::numeric_limits<unsigned>::max();
1421 C.ImmCost = std::numeric_limits<unsigned>::max();
1422 C.SetupCost = std::numeric_limits<unsigned>::max();
1423 C.ScaleCost = std::numeric_limits<unsigned>::max();
1424}
1425
1426/// Choose the lower cost.
1427bool Cost::isLess(Cost &Other) {
1428 if (InsnsCost.getNumOccurrences() > 0 && InsnsCost &&
1429 C.Insns != Other.C.Insns)
1430 return C.Insns < Other.C.Insns;
1431 return TTI->isLSRCostLess(C, Other.C);
1432}
1433
1434#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1435void Cost::print(raw_ostream &OS) const {
1436 if (InsnsCost)
1437 OS << C.Insns << " instruction" << (C.Insns == 1 ? " " : "s ");
1438 OS << C.NumRegs << " reg" << (C.NumRegs == 1 ? "" : "s");
1439 if (C.AddRecCost != 0)
1440 OS << ", with addrec cost " << C.AddRecCost;
1441 if (C.NumIVMuls != 0)
1442 OS << ", plus " << C.NumIVMuls << " IV mul"
1443 << (C.NumIVMuls == 1 ? "" : "s");
1444 if (C.NumBaseAdds != 0)
1445 OS << ", plus " << C.NumBaseAdds << " base add"
1446 << (C.NumBaseAdds == 1 ? "" : "s");
1447 if (C.ScaleCost != 0)
1448 OS << ", plus " << C.ScaleCost << " scale cost";
1449 if (C.ImmCost != 0)
1450 OS << ", plus " << C.ImmCost << " imm cost";
1451 if (C.SetupCost != 0)
1452 OS << ", plus " << C.SetupCost << " setup cost";
1453}
1454
1455LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void Cost::dump() const {
1456 print(errs()); errs() << '\n';
1457}
1458#endif
1459
1460/// Test whether this fixup always uses its value outside of the given loop.
1461bool LSRFixup::isUseFullyOutsideLoop(const Loop *L) const {
1462 // PHI nodes use their value in their incoming blocks.
1463 if (const PHINode *PN = dyn_cast<PHINode>(UserInst)) {
1464 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
1465 if (PN->getIncomingValue(i) == OperandValToReplace &&
1466 L->contains(PN->getIncomingBlock(i)))
1467 return false;
1468 return true;
1469 }
1470
1471 return !L->contains(UserInst);
1472}
1473
1474#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1475void LSRFixup::print(raw_ostream &OS) const {
1476 OS << "UserInst=";
1477 // Store is common and interesting enough to be worth special-casing.
1478 if (StoreInst *Store = dyn_cast<StoreInst>(UserInst)) {
1479 OS << "store ";
1480 Store->getOperand(0)->printAsOperand(OS, /*PrintType=*/false);
1481 } else if (UserInst->getType()->isVoidTy())
1482 OS << UserInst->getOpcodeName();
1483 else
1484 UserInst->printAsOperand(OS, /*PrintType=*/false);
1485
1486 OS << ", OperandValToReplace=";
1487 OperandValToReplace->printAsOperand(OS, /*PrintType=*/false);
1488
1489 for (const Loop *PIL : PostIncLoops) {
1490 OS << ", PostIncLoop=";
1491 PIL->getHeader()->printAsOperand(OS, /*PrintType=*/false);
1492 }
1493
1494 if (Offset != 0)
1495 OS << ", Offset=" << Offset;
1496}
1497
1498LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void LSRFixup::dump() const {
1499 print(errs()); errs() << '\n';
1500}
1501#endif
1502
1503/// Test whether this use as a formula which has the same registers as the given
1504/// formula.
1505bool LSRUse::HasFormulaWithSameRegs(const Formula &F) const {
1506 SmallVector<const SCEV *, 4> Key = F.BaseRegs;
1507 if (F.ScaledReg) Key.push_back(F.ScaledReg);
1508 // Unstable sort by host order ok, because this is only used for uniquifying.
1509 llvm::sort(Key);
1510 return Uniquifier.count(Key);
1511}
1512
1513/// The function returns a probability of selecting formula without Reg.
1514float LSRUse::getNotSelectedProbability(const SCEV *Reg) const {
1515 unsigned FNum = 0;
1516 for (const Formula &F : Formulae)
1517 if (F.referencesReg(Reg))
1518 FNum++;
1519 return ((float)(Formulae.size() - FNum)) / Formulae.size();
1520}
1521
1522/// If the given formula has not yet been inserted, add it to the list, and
1523/// return true. Return false otherwise. The formula must be in canonical form.
1524bool LSRUse::InsertFormula(const Formula &F, const Loop &L) {
1525 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1525, __PRETTY_FUNCTION__))
;
1526
1527 if (!Formulae.empty() && RigidFormula)
1528 return false;
1529
1530 SmallVector<const SCEV *, 4> Key = F.BaseRegs;
1531 if (F.ScaledReg) Key.push_back(F.ScaledReg);
1532 // Unstable sort by host order ok, because this is only used for uniquifying.
1533 llvm::sort(Key);
1534
1535 if (!Uniquifier.insert(Key).second)
1536 return false;
1537
1538 // Using a register to hold the value of 0 is not profitable.
1539 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1540, __PRETTY_FUNCTION__))
1540 "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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1540, __PRETTY_FUNCTION__))
;
1541#ifndef NDEBUG
1542 for (const SCEV *BaseReg : F.BaseRegs)
1543 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1543, __PRETTY_FUNCTION__))
;
1544#endif
1545
1546 // Add the formula to the list.
1547 Formulae.push_back(F);
1548
1549 // Record registers now being used by this use.
1550 Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end());
1551 if (F.ScaledReg)
1552 Regs.insert(F.ScaledReg);
1553
1554 return true;
1555}
1556
1557/// Remove the given formula from this use's list.
1558void LSRUse::DeleteFormula(Formula &F) {
1559 if (&F != &Formulae.back())
1560 std::swap(F, Formulae.back());
1561 Formulae.pop_back();
1562}
1563
1564/// Recompute the Regs field, and update RegUses.
1565void LSRUse::RecomputeRegs(size_t LUIdx, RegUseTracker &RegUses) {
1566 // Now that we've filtered out some formulae, recompute the Regs set.
1567 SmallPtrSet<const SCEV *, 4> OldRegs = std::move(Regs);
1568 Regs.clear();
1569 for (const Formula &F : Formulae) {
1570 if (F.ScaledReg) Regs.insert(F.ScaledReg);
1571 Regs.insert(F.BaseRegs.begin(), F.BaseRegs.end());
1572 }
1573
1574 // Update the RegTracker.
1575 for (const SCEV *S : OldRegs)
1576 if (!Regs.count(S))
1577 RegUses.dropRegister(S, LUIdx);
1578}
1579
1580#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1581void LSRUse::print(raw_ostream &OS) const {
1582 OS << "LSR Use: Kind=";
1583 switch (Kind) {
1584 case Basic: OS << "Basic"; break;
1585 case Special: OS << "Special"; break;
1586 case ICmpZero: OS << "ICmpZero"; break;
1587 case Address:
1588 OS << "Address of ";
1589 if (AccessTy.MemTy->isPointerTy())
1590 OS << "pointer"; // the full pointer type could be really verbose
1591 else {
1592 OS << *AccessTy.MemTy;
1593 }
1594
1595 OS << " in addrspace(" << AccessTy.AddrSpace << ')';
1596 }
1597
1598 OS << ", Offsets={";
1599 bool NeedComma = false;
1600 for (const LSRFixup &Fixup : Fixups) {
1601 if (NeedComma) OS << ',';
1602 OS << Fixup.Offset;
1603 NeedComma = true;
1604 }
1605 OS << '}';
1606
1607 if (AllFixupsOutsideLoop)
1608 OS << ", all-fixups-outside-loop";
1609
1610 if (WidestFixupType)
1611 OS << ", widest fixup type: " << *WidestFixupType;
1612}
1613
1614LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void LSRUse::dump() const {
1615 print(errs()); errs() << '\n';
1616}
1617#endif
1618
1619static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1620 LSRUse::KindType Kind, MemAccessTy AccessTy,
1621 GlobalValue *BaseGV, int64_t BaseOffset,
1622 bool HasBaseReg, int64_t Scale,
1623 Instruction *Fixup/*= nullptr*/) {
1624 switch (Kind) {
1625 case LSRUse::Address:
1626 return TTI.isLegalAddressingMode(AccessTy.MemTy, BaseGV, BaseOffset,
1627 HasBaseReg, Scale, AccessTy.AddrSpace, Fixup);
1628
1629 case LSRUse::ICmpZero:
1630 // There's not even a target hook for querying whether it would be legal to
1631 // fold a GV into an ICmp.
1632 if (BaseGV)
1633 return false;
1634
1635 // ICmp only has two operands; don't allow more than two non-trivial parts.
1636 if (Scale != 0 && HasBaseReg && BaseOffset != 0)
1637 return false;
1638
1639 // ICmp only supports no scale or a -1 scale, as we can "fold" a -1 scale by
1640 // putting the scaled register in the other operand of the icmp.
1641 if (Scale != 0 && Scale != -1)
1642 return false;
1643
1644 // If we have low-level target information, ask the target if it can fold an
1645 // integer immediate on an icmp.
1646 if (BaseOffset != 0) {
1647 // We have one of:
1648 // ICmpZero BaseReg + BaseOffset => ICmp BaseReg, -BaseOffset
1649 // ICmpZero -1*ScaleReg + BaseOffset => ICmp ScaleReg, BaseOffset
1650 // Offs is the ICmp immediate.
1651 if (Scale == 0)
1652 // The cast does the right thing with
1653 // std::numeric_limits<int64_t>::min().
1654 BaseOffset = -(uint64_t)BaseOffset;
1655 return TTI.isLegalICmpImmediate(BaseOffset);
1656 }
1657
1658 // ICmpZero BaseReg + -1*ScaleReg => ICmp BaseReg, ScaleReg
1659 return true;
1660
1661 case LSRUse::Basic:
1662 // Only handle single-register values.
1663 return !BaseGV && Scale == 0 && BaseOffset == 0;
1664
1665 case LSRUse::Special:
1666 // Special case Basic to handle -1 scales.
1667 return !BaseGV && (Scale == 0 || Scale == -1) && BaseOffset == 0;
1668 }
1669
1670 llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1670)
;
1671}
1672
1673static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1674 int64_t MinOffset, int64_t MaxOffset,
1675 LSRUse::KindType Kind, MemAccessTy AccessTy,
1676 GlobalValue *BaseGV, int64_t BaseOffset,
1677 bool HasBaseReg, int64_t Scale) {
1678 // Check for overflow.
1679 if (((int64_t)((uint64_t)BaseOffset + MinOffset) > BaseOffset) !=
1680 (MinOffset > 0))
1681 return false;
1682 MinOffset = (uint64_t)BaseOffset + MinOffset;
1683 if (((int64_t)((uint64_t)BaseOffset + MaxOffset) > BaseOffset) !=
1684 (MaxOffset > 0))
1685 return false;
1686 MaxOffset = (uint64_t)BaseOffset + MaxOffset;
1687
1688 return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MinOffset,
1689 HasBaseReg, Scale) &&
1690 isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, MaxOffset,
1691 HasBaseReg, Scale);
1692}
1693
1694static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1695 int64_t MinOffset, int64_t MaxOffset,
1696 LSRUse::KindType Kind, MemAccessTy AccessTy,
1697 const Formula &F, const Loop &L) {
1698 // For the purpose of isAMCompletelyFolded either having a canonical formula
1699 // or a scale not equal to zero is correct.
1700 // Problems may arise from non canonical formulae having a scale == 0.
1701 // Strictly speaking it would best to just rely on canonical formulae.
1702 // However, when we generate the scaled formulae, we first check that the
1703 // scaling factor is profitable before computing the actual ScaledReg for
1704 // compile time sake.
1705 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1705, __PRETTY_FUNCTION__))
;
1706 return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy,
1707 F.BaseGV, F.BaseOffset, F.HasBaseReg, F.Scale);
1708}
1709
1710/// Test whether we know how to expand the current formula.
1711static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset,
1712 int64_t MaxOffset, LSRUse::KindType Kind,
1713 MemAccessTy AccessTy, GlobalValue *BaseGV,
1714 int64_t BaseOffset, bool HasBaseReg, int64_t Scale) {
1715 // We know how to expand completely foldable formulae.
1716 return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV,
1717 BaseOffset, HasBaseReg, Scale) ||
1718 // Or formulae that use a base register produced by a sum of base
1719 // registers.
1720 (Scale == 1 &&
1721 isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy,
1722 BaseGV, BaseOffset, true, 0));
1723}
1724
1725static bool isLegalUse(const TargetTransformInfo &TTI, int64_t MinOffset,
1726 int64_t MaxOffset, LSRUse::KindType Kind,
1727 MemAccessTy AccessTy, const Formula &F) {
1728 return isLegalUse(TTI, MinOffset, MaxOffset, Kind, AccessTy, F.BaseGV,
1729 F.BaseOffset, F.HasBaseReg, F.Scale);
1730}
1731
1732static bool isAMCompletelyFolded(const TargetTransformInfo &TTI,
1733 const LSRUse &LU, const Formula &F) {
1734 // Target may want to look at the user instructions.
1735 if (LU.Kind == LSRUse::Address && TTI.LSRWithInstrQueries()) {
1736 for (const LSRFixup &Fixup : LU.Fixups)
1737 if (!isAMCompletelyFolded(TTI, LSRUse::Address, LU.AccessTy, F.BaseGV,
1738 (F.BaseOffset + Fixup.Offset), F.HasBaseReg,
1739 F.Scale, Fixup.UserInst))
1740 return false;
1741 return true;
1742 }
1743
1744 return isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind,
1745 LU.AccessTy, F.BaseGV, F.BaseOffset, F.HasBaseReg,
1746 F.Scale);
1747}
1748
1749static unsigned getScalingFactorCost(const TargetTransformInfo &TTI,
1750 const LSRUse &LU, const Formula &F,
1751 const Loop &L) {
1752 if (!F.Scale)
1753 return 0;
1754
1755 // If the use is not completely folded in that instruction, we will have to
1756 // pay an extra cost only for scale != 1.
1757 if (!isAMCompletelyFolded(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind,
1758 LU.AccessTy, F, L))
1759 return F.Scale != 1;
1760
1761 switch (LU.Kind) {
1762 case LSRUse::Address: {
1763 // Check the scaling factor cost with both the min and max offsets.
1764 int ScaleCostMinOffset = TTI.getScalingFactorCost(
1765 LU.AccessTy.MemTy, F.BaseGV, F.BaseOffset + LU.MinOffset, F.HasBaseReg,
1766 F.Scale, LU.AccessTy.AddrSpace);
1767 int ScaleCostMaxOffset = TTI.getScalingFactorCost(
1768 LU.AccessTy.MemTy, F.BaseGV, F.BaseOffset + LU.MaxOffset, F.HasBaseReg,
1769 F.Scale, LU.AccessTy.AddrSpace);
1770
1771 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1772, __PRETTY_FUNCTION__))
1772 "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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1772, __PRETTY_FUNCTION__))
;
1773 return std::max(ScaleCostMinOffset, ScaleCostMaxOffset);
1774 }
1775 case LSRUse::ICmpZero:
1776 case LSRUse::Basic:
1777 case LSRUse::Special:
1778 // The use is completely folded, i.e., everything is folded into the
1779 // instruction.
1780 return 0;
1781 }
1782
1783 llvm_unreachable("Invalid LSRUse Kind!")::llvm::llvm_unreachable_internal("Invalid LSRUse Kind!", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1783)
;
1784}
1785
1786static bool isAlwaysFoldable(const TargetTransformInfo &TTI,
1787 LSRUse::KindType Kind, MemAccessTy AccessTy,
1788 GlobalValue *BaseGV, int64_t BaseOffset,
1789 bool HasBaseReg) {
1790 // Fast-path: zero is always foldable.
1791 if (BaseOffset == 0 && !BaseGV) return true;
1792
1793 // Conservatively, create an address with an immediate and a
1794 // base and a scale.
1795 int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1;
1796
1797 // Canonicalize a scale of 1 to a base register if the formula doesn't
1798 // already have a base register.
1799 if (!HasBaseReg && Scale == 1) {
1800 Scale = 0;
1801 HasBaseReg = true;
1802 }
1803
1804 return isAMCompletelyFolded(TTI, Kind, AccessTy, BaseGV, BaseOffset,
1805 HasBaseReg, Scale);
1806}
1807
1808static bool isAlwaysFoldable(const TargetTransformInfo &TTI,
1809 ScalarEvolution &SE, int64_t MinOffset,
1810 int64_t MaxOffset, LSRUse::KindType Kind,
1811 MemAccessTy AccessTy, const SCEV *S,
1812 bool HasBaseReg) {
1813 // Fast-path: zero is always foldable.
1814 if (S->isZero()) return true;
1815
1816 // Conservatively, create an address with an immediate and a
1817 // base and a scale.
1818 int64_t BaseOffset = ExtractImmediate(S, SE);
1819 GlobalValue *BaseGV = ExtractSymbol(S, SE);
1820
1821 // If there's anything else involved, it's not foldable.
1822 if (!S->isZero()) return false;
1823
1824 // Fast-path: zero is always foldable.
1825 if (BaseOffset == 0 && !BaseGV) return true;
1826
1827 // Conservatively, create an address with an immediate and a
1828 // base and a scale.
1829 int64_t Scale = Kind == LSRUse::ICmpZero ? -1 : 1;
1830
1831 return isAMCompletelyFolded(TTI, MinOffset, MaxOffset, Kind, AccessTy, BaseGV,
1832 BaseOffset, HasBaseReg, Scale);
1833}
1834
1835namespace {
1836
1837/// An individual increment in a Chain of IV increments. Relate an IV user to
1838/// an expression that computes the IV it uses from the IV used by the previous
1839/// link in the Chain.
1840///
1841/// For the head of a chain, IncExpr holds the absolute SCEV expression for the
1842/// original IVOperand. The head of the chain's IVOperand is only valid during
1843/// chain collection, before LSR replaces IV users. During chain generation,
1844/// IncExpr can be used to find the new IVOperand that computes the same
1845/// expression.
1846struct IVInc {
1847 Instruction *UserInst;
1848 Value* IVOperand;
1849 const SCEV *IncExpr;
1850
1851 IVInc(Instruction *U, Value *O, const SCEV *E)
1852 : UserInst(U), IVOperand(O), IncExpr(E) {}
1853};
1854
1855// The list of IV increments in program order. We typically add the head of a
1856// chain without finding subsequent links.
1857struct IVChain {
1858 SmallVector<IVInc, 1> Incs;
1859 const SCEV *ExprBase = nullptr;
1860
1861 IVChain() = default;
1862 IVChain(const IVInc &Head, const SCEV *Base)
1863 : Incs(1, Head), ExprBase(Base) {}
1864
1865 using const_iterator = SmallVectorImpl<IVInc>::const_iterator;
1866
1867 // Return the first increment in the chain.
1868 const_iterator begin() const {
1869 assert(!Incs.empty())((!Incs.empty()) ? static_cast<void> (0) : __assert_fail
("!Incs.empty()", "/build/llvm-toolchain-snapshot-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 1869, __PRETTY_FUNCTION__))
;
1870 return std::next(Incs.begin());
1871 }
1872 const_iterator end() const {
1873 return Incs.end();
1874 }
1875
1876 // Returns true if this chain contains any increments.
1877 bool hasIncs() const { return Incs.size() >= 2; }
1878
1879 // Add an IVInc to the end of this chain.
1880 void add(const IVInc &X) { Incs.push_back(X); }
1881
1882 // Returns the last UserInst in the chain.
1883 Instruction *tailUserInst() const { return Incs.back().UserInst; }
1884
1885 // Returns true if IncExpr can be profitably added to this chain.
1886 bool isProfitableIncrement(const SCEV *OperExpr,
1887 const SCEV *IncExpr,
1888 ScalarEvolution&);
1889};
1890
1891/// Helper for CollectChains to track multiple IV increment uses. Distinguish
1892/// between FarUsers that definitely cross IV increments and NearUsers that may
1893/// be used between IV increments.
1894struct ChainUsers {
1895 SmallPtrSet<Instruction*, 4> FarUsers;
1896 SmallPtrSet<Instruction*, 4> NearUsers;
1897};
1898
1899/// This class holds state for the main loop strength reduction logic.
1900class LSRInstance {
1901 IVUsers &IU;
1902 ScalarEvolution &SE;
1903 DominatorTree &DT;
1904 LoopInfo &LI;
1905 AssumptionCache &AC;
1906 TargetLibraryInfo &TLI;
1907 const TargetTransformInfo &TTI;
1908 Loop *const L;
1909 MemorySSAUpdater *MSSAU;
1910 bool FavorBackedgeIndex = false;
1911 bool Changed = false;
1912
1913 /// This is the insert position that the current loop's induction variable
1914 /// increment should be placed. In simple loops, this is the latch block's
1915 /// terminator. But in more complicated cases, this is a position which will
1916 /// dominate all the in-loop post-increment users.
1917 Instruction *IVIncInsertPos = nullptr;
1918
1919 /// Interesting factors between use strides.
1920 ///
1921 /// We explicitly use a SetVector which contains a SmallSet, instead of the
1922 /// default, a SmallDenseSet, because we need to use the full range of
1923 /// int64_ts, and there's currently no good way of doing that with
1924 /// SmallDenseSet.
1925 SetVector<int64_t, SmallVector<int64_t, 8>, SmallSet<int64_t, 8>> Factors;
1926
1927 /// Interesting use types, to facilitate truncation reuse.
1928 SmallSetVector<Type *, 4> Types;
1929
1930 /// The list of interesting uses.
1931 mutable SmallVector<LSRUse, 16> Uses;
1932
1933 /// Track which uses use which register candidates.
1934 RegUseTracker RegUses;
1935
1936 // Limit the number of chains to avoid quadratic behavior. We don't expect to
1937 // have more than a few IV increment chains in a loop. Missing a Chain falls
1938 // back to normal LSR behavior for those uses.
1939 static const unsigned MaxChains = 8;
1940
1941 /// IV users can form a chain of IV increments.
1942 SmallVector<IVChain, MaxChains> IVChainVec;
1943
1944 /// IV users that belong to profitable IVChains.
1945 SmallPtrSet<Use*, MaxChains> IVIncSet;
1946
1947 void OptimizeShadowIV();
1948 bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse);
1949 ICmpInst *OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse);
1950 void OptimizeLoopTermCond();
1951
1952 void ChainInstruction(Instruction *UserInst, Instruction *IVOper,
1953 SmallVectorImpl<ChainUsers> &ChainUsersVec);
1954 void FinalizeChain(IVChain &Chain);
1955 void CollectChains();
1956 void GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter,
1957 SmallVectorImpl<WeakTrackingVH> &DeadInsts);
1958
1959 void CollectInterestingTypesAndFactors();
1960 void CollectFixupsAndInitialFormulae();
1961
1962 // Support for sharing of LSRUses between LSRFixups.
1963 using UseMapTy = DenseMap<LSRUse::SCEVUseKindPair, size_t>;
1964 UseMapTy UseMap;
1965
1966 bool reconcileNewOffset(LSRUse &LU, int64_t NewOffset, bool HasBaseReg,
1967 LSRUse::KindType Kind, MemAccessTy AccessTy);
1968
1969 std::pair<size_t, int64_t> getUse(const SCEV *&Expr, LSRUse::KindType Kind,
1970 MemAccessTy AccessTy);
1971
1972 void DeleteUse(LSRUse &LU, size_t LUIdx);
1973
1974 LSRUse *FindUseWithSimilarFormula(const Formula &F, const LSRUse &OrigLU);
1975
1976 void InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx);
1977 void InsertSupplementalFormula(const SCEV *S, LSRUse &LU, size_t LUIdx);
1978 void CountRegisters(const Formula &F, size_t LUIdx);
1979 bool InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F);
1980
1981 void CollectLoopInvariantFixupsAndFormulae();
1982
1983 void GenerateReassociations(LSRUse &LU, unsigned LUIdx, Formula Base,
1984 unsigned Depth = 0);
1985
1986 void GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,
1987 const Formula &Base, unsigned Depth,
1988 size_t Idx, bool IsScaledReg = false);
1989 void GenerateCombinations(LSRUse &LU, unsigned LUIdx, Formula Base);
1990 void GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx,
1991 const Formula &Base, size_t Idx,
1992 bool IsScaledReg = false);
1993 void GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx, Formula Base);
1994 void GenerateConstantOffsetsImpl(LSRUse &LU, unsigned LUIdx,
1995 const Formula &Base,
1996 const SmallVectorImpl<int64_t> &Worklist,
1997 size_t Idx, bool IsScaledReg = false);
1998 void GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx, Formula Base);
1999 void GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, Formula Base);
2000 void GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base);
2001 void GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base);
2002 void GenerateCrossUseConstantOffsets();
2003 void GenerateAllReuseFormulae();
2004
2005 void FilterOutUndesirableDedicatedRegisters();
2006
2007 size_t EstimateSearchSpaceComplexity() const;
2008 void NarrowSearchSpaceByDetectingSupersets();
2009 void NarrowSearchSpaceByCollapsingUnrolledCode();
2010 void NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters();
2011 void NarrowSearchSpaceByFilterFormulaWithSameScaledReg();
2012 void NarrowSearchSpaceByFilterPostInc();
2013 void NarrowSearchSpaceByDeletingCostlyFormulas();
2014 void NarrowSearchSpaceByPickingWinnerRegs();
2015 void NarrowSearchSpaceUsingHeuristics();
2016
2017 void SolveRecurse(SmallVectorImpl<const Formula *> &Solution,
2018 Cost &SolutionCost,
2019 SmallVectorImpl<const Formula *> &Workspace,
2020 const Cost &CurCost,
2021 const SmallPtrSet<const SCEV *, 16> &CurRegs,
2022 DenseSet<const SCEV *> &VisitedRegs) const;
2023 void Solve(SmallVectorImpl<const Formula *> &Solution) const;
2024
2025 BasicBlock::iterator
2026 HoistInsertPosition(BasicBlock::iterator IP,
2027 const SmallVectorImpl<Instruction *> &Inputs) const;
2028 BasicBlock::iterator
2029 AdjustInsertPositionForExpand(BasicBlock::iterator IP,
2030 const LSRFixup &LF,
2031 const LSRUse &LU,
2032 SCEVExpander &Rewriter) const;
2033
2034 Value *Expand(const LSRUse &LU, const LSRFixup &LF, const Formula &F,
2035 BasicBlock::iterator IP, SCEVExpander &Rewriter,
2036 SmallVectorImpl<WeakTrackingVH> &DeadInsts) const;
2037 void RewriteForPHI(PHINode *PN, const LSRUse &LU, const LSRFixup &LF,
2038 const Formula &F, SCEVExpander &Rewriter,
2039 SmallVectorImpl<WeakTrackingVH> &DeadInsts) const;
2040 void Rewrite(const LSRUse &LU, const LSRFixup &LF, const Formula &F,
2041 SCEVExpander &Rewriter,
2042 SmallVectorImpl<WeakTrackingVH> &DeadInsts) const;
2043 void ImplementSolution(const SmallVectorImpl<const Formula *> &Solution);
2044
2045public:
2046 LSRInstance(Loop *L, IVUsers &IU, ScalarEvolution &SE, DominatorTree &DT,
2047 LoopInfo &LI, const TargetTransformInfo &TTI, AssumptionCache &AC,
2048 TargetLibraryInfo &TLI, MemorySSAUpdater *MSSAU);
2049
2050 bool getChanged() const { return Changed; }
2051
2052 void print_factors_and_types(raw_ostream &OS) const;
2053 void print_fixups(raw_ostream &OS) const;
2054 void print_uses(raw_ostream &OS) const;
2055 void print(raw_ostream &OS) const;
2056 void dump() const;
2057};
2058
2059} // end anonymous namespace
2060
2061/// If IV is used in a int-to-float cast inside the loop then try to eliminate
2062/// the cast operation.
2063void LSRInstance::OptimizeShadowIV() {
2064 const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);
2065 if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))
2066 return;
2067
2068 for (IVUsers::const_iterator UI = IU.begin(), E = IU.end();
2069 UI != E; /* empty */) {
2070 IVUsers::const_iterator CandidateUI = UI;
2071 ++UI;
2072 Instruction *ShadowUse = CandidateUI->getUser();
2073 Type *DestTy = nullptr;
2074 bool IsSigned = false;
2075
2076 /* If shadow use is a int->float cast then insert a second IV
2077 to eliminate this cast.
2078
2079 for (unsigned i = 0; i < n; ++i)
2080 foo((double)i);
2081
2082 is transformed into
2083
2084 double d = 0.0;
2085 for (unsigned i = 0; i < n; ++i, ++d)
2086 foo(d);
2087 */
2088 if (UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->getUser())) {
2089 IsSigned = false;
2090 DestTy = UCast->getDestTy();
2091 }
2092 else if (SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->getUser())) {
2093 IsSigned = true;
2094 DestTy = SCast->getDestTy();
2095 }
2096 if (!DestTy) continue;
2097
2098 // If target does not support DestTy natively then do not apply
2099 // this transformation.
2100 if (!TTI.isTypeLegal(DestTy)) continue;
2101
2102 PHINode *PH = dyn_cast<PHINode>(ShadowUse->getOperand(0));
2103 if (!PH) continue;
2104 if (PH->getNumIncomingValues() != 2) continue;
2105
2106 // If the calculation in integers overflows, the result in FP type will
2107 // differ. So we only can do this transformation if we are guaranteed to not
2108 // deal with overflowing values
2109 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SE.getSCEV(PH));
2110 if (!AR) continue;
2111 if (IsSigned && !AR->hasNoSignedWrap()) continue;
2112 if (!IsSigned && !AR->hasNoUnsignedWrap()) continue;
2113
2114 Type *SrcTy = PH->getType();
2115 int Mantissa = DestTy->getFPMantissaWidth();
2116 if (Mantissa == -1) continue;
2117 if ((int)SE.getTypeSizeInBits(SrcTy) > Mantissa)
2118 continue;
2119
2120 unsigned Entry, Latch;
2121 if (PH->getIncomingBlock(0) == L->getLoopPreheader()) {
2122 Entry = 0;
2123 Latch = 1;
2124 } else {
2125 Entry = 1;
2126 Latch = 0;
2127 }
2128
2129 ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry));
2130 if (!Init) continue;
2131 Constant *NewInit = ConstantFP::get(DestTy, IsSigned ?
2132 (double)Init->getSExtValue() :
2133 (double)Init->getZExtValue());
2134
2135 BinaryOperator *Incr =
2136 dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch));
2137 if (!Incr) continue;
2138 if (Incr->getOpcode() != Instruction::Add
2139 && Incr->getOpcode() != Instruction::Sub)
2140 continue;
2141
2142 /* Initialize new IV, double d = 0.0 in above example. */
2143 ConstantInt *C = nullptr;
2144 if (Incr->getOperand(0) == PH)
2145 C = dyn_cast<ConstantInt>(Incr->getOperand(1));
2146 else if (Incr->getOperand(1) == PH)
2147 C = dyn_cast<ConstantInt>(Incr->getOperand(0));
2148 else
2149 continue;
2150
2151 if (!C) continue;
2152
2153 // Ignore negative constants, as the code below doesn't handle them
2154 // correctly. TODO: Remove this restriction.
2155 if (!C->getValue().isStrictlyPositive()) continue;
2156
2157 /* Add new PHINode. */
2158 PHINode *NewPH = PHINode::Create(DestTy, 2, "IV.S.", PH);
2159
2160 /* create new increment. '++d' in above example. */
2161 Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue());
2162 BinaryOperator *NewIncr =
2163 BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ?
2164 Instruction::FAdd : Instruction::FSub,
2165 NewPH, CFP, "IV.S.next.", Incr);
2166
2167 NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry));
2168 NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch));
2169
2170 /* Remove cast operation */
2171 ShadowUse->replaceAllUsesWith(NewPH);
2172 ShadowUse->eraseFromParent();
2173 Changed = true;
2174 break;
2175 }
2176}
2177
2178/// If Cond has an operand that is an expression of an IV, set the IV user and
2179/// stride information and return true, otherwise return false.
2180bool LSRInstance::FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse) {
2181 for (IVStrideUse &U : IU)
2182 if (U.getUser() == Cond) {
2183 // NOTE: we could handle setcc instructions with multiple uses here, but
2184 // InstCombine does it as well for simple uses, it's not clear that it
2185 // occurs enough in real life to handle.
2186 CondUse = &U;
2187 return true;
2188 }
2189 return false;
2190}
2191
2192/// Rewrite the loop's terminating condition if it uses a max computation.
2193///
2194/// This is a narrow solution to a specific, but acute, problem. For loops
2195/// like this:
2196///
2197/// i = 0;
2198/// do {
2199/// p[i] = 0.0;
2200/// } while (++i < n);
2201///
2202/// the trip count isn't just 'n', because 'n' might not be positive. And
2203/// unfortunately this can come up even for loops where the user didn't use
2204/// a C do-while loop. For example, seemingly well-behaved top-test loops
2205/// will commonly be lowered like this:
2206///
2207/// if (n > 0) {
2208/// i = 0;
2209/// do {
2210/// p[i] = 0.0;
2211/// } while (++i < n);
2212/// }
2213///
2214/// and then it's possible for subsequent optimization to obscure the if
2215/// test in such a way that indvars can't find it.
2216///
2217/// When indvars can't find the if test in loops like this, it creates a
2218/// max expression, which allows it to give the loop a canonical
2219/// induction variable:
2220///
2221/// i = 0;
2222/// max = n < 1 ? 1 : n;
2223/// do {
2224/// p[i] = 0.0;
2225/// } while (++i != max);
2226///
2227/// Canonical induction variables are necessary because the loop passes
2228/// are designed around them. The most obvious example of this is the
2229/// LoopInfo analysis, which doesn't remember trip count values. It
2230/// expects to be able to rediscover the trip count each time it is
2231/// needed, and it does this using a simple analysis that only succeeds if
2232/// the loop has a canonical induction variable.
2233///
2234/// However, when it comes time to generate code, the maximum operation
2235/// can be quite costly, especially if it's inside of an outer loop.
2236///
2237/// This function solves this problem by detecting this type of loop and
2238/// rewriting their conditions from ICMP_NE back to ICMP_SLT, and deleting
2239/// the instructions for the maximum computation.
2240ICmpInst *LSRInstance::OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse) {
2241 // Check that the loop matches the pattern we're looking for.
2242 if (Cond->getPredicate() != CmpInst::ICMP_EQ &&
2243 Cond->getPredicate() != CmpInst::ICMP_NE)
2244 return Cond;
2245
2246 SelectInst *Sel = dyn_cast<SelectInst>(Cond->getOperand(1));
2247 if (!Sel || !Sel->hasOneUse()) return Cond;
2248
2249 const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);
2250 if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))
2251 return Cond;
2252 const SCEV *One = SE.getConstant(BackedgeTakenCount->getType(), 1);
2253
2254 // Add one to the backedge-taken count to get the trip count.
2255 const SCEV *IterationCount = SE.getAddExpr(One, BackedgeTakenCount);
2256 if (IterationCount != SE.getSCEV(Sel)) return Cond;
2257
2258 // Check for a max calculation that matches the pattern. There's no check
2259 // for ICMP_ULE here because the comparison would be with zero, which
2260 // isn't interesting.
2261 CmpInst::Predicate Pred = ICmpInst::BAD_ICMP_PREDICATE;
2262 const SCEVNAryExpr *Max = nullptr;
2263 if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(BackedgeTakenCount)) {
2264 Pred = ICmpInst::ICMP_SLE;
2265 Max = S;
2266 } else if (const SCEVSMaxExpr *S = dyn_cast<SCEVSMaxExpr>(IterationCount)) {
2267 Pred = ICmpInst::ICMP_SLT;
2268 Max = S;
2269 } else if (const SCEVUMaxExpr *U = dyn_cast<SCEVUMaxExpr>(IterationCount)) {
2270 Pred = ICmpInst::ICMP_ULT;
2271 Max = U;
2272 } else {
2273 // No match; bail.
2274 return Cond;
2275 }
2276
2277 // To handle a max with more than two operands, this optimization would
2278 // require additional checking and setup.
2279 if (Max->getNumOperands() != 2)
2280 return Cond;
2281
2282 const SCEV *MaxLHS = Max->getOperand(0);
2283 const SCEV *MaxRHS = Max->getOperand(1);
2284
2285 // ScalarEvolution canonicalizes constants to the left. For < and >, look
2286 // for a comparison with 1. For <= and >=, a comparison with zero.
2287 if (!MaxLHS ||
2288 (ICmpInst::isTrueWhenEqual(Pred) ? !MaxLHS->isZero() : (MaxLHS != One)))
2289 return Cond;
2290
2291 // Check the relevant induction variable for conformance to
2292 // the pattern.
2293 const SCEV *IV = SE.getSCEV(Cond->getOperand(0));
2294 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(IV);
2295 if (!AR || !AR->isAffine() ||
2296 AR->getStart() != One ||
2297 AR->getStepRecurrence(SE) != One)
2298 return Cond;
2299
2300 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2301, __PRETTY_FUNCTION__))
2301 "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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2301, __PRETTY_FUNCTION__))
;
2302
2303 // Check the right operand of the select, and remember it, as it will
2304 // be used in the new comparison instruction.
2305 Value *NewRHS = nullptr;
2306 if (ICmpInst::isTrueWhenEqual(Pred)) {
2307 // Look for n+1, and grab n.
2308 if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(1)))
2309 if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1)))
2310 if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS)
2311 NewRHS = BO->getOperand(0);
2312 if (AddOperator *BO = dyn_cast<AddOperator>(Sel->getOperand(2)))
2313 if (ConstantInt *BO1 = dyn_cast<ConstantInt>(BO->getOperand(1)))
2314 if (BO1->isOne() && SE.getSCEV(BO->getOperand(0)) == MaxRHS)
2315 NewRHS = BO->getOperand(0);
2316 if (!NewRHS)
2317 return Cond;
2318 } else if (SE.getSCEV(Sel->getOperand(1)) == MaxRHS)
2319 NewRHS = Sel->getOperand(1);
2320 else if (SE.getSCEV(Sel->getOperand(2)) == MaxRHS)
2321 NewRHS = Sel->getOperand(2);
2322 else if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(MaxRHS))
2323 NewRHS = SU->getValue();
2324 else
2325 // Max doesn't match expected pattern.
2326 return Cond;
2327
2328 // Determine the new comparison opcode. It may be signed or unsigned,
2329 // and the original comparison may be either equality or inequality.
2330 if (Cond->getPredicate() == CmpInst::ICMP_EQ)
2331 Pred = CmpInst::getInversePredicate(Pred);
2332
2333 // Ok, everything looks ok to change the condition into an SLT or SGE and
2334 // delete the max calculation.
2335 ICmpInst *NewCond =
2336 new ICmpInst(Cond, Pred, Cond->getOperand(0), NewRHS, "scmp");
2337
2338 // Delete the max calculation instructions.
2339 Cond->replaceAllUsesWith(NewCond);
2340 CondUse->setUser(NewCond);
2341 Instruction *Cmp = cast<Instruction>(Sel->getOperand(0));
2342 Cond->eraseFromParent();
2343 Sel->eraseFromParent();
2344 if (Cmp->use_empty())
2345 Cmp->eraseFromParent();
2346 return NewCond;
2347}
2348
2349/// Change loop terminating condition to use the postinc iv when possible.
2350void
2351LSRInstance::OptimizeLoopTermCond() {
2352 SmallPtrSet<Instruction *, 4> PostIncs;
2353
2354 // We need a different set of heuristics for rotated and non-rotated loops.
2355 // If a loop is rotated then the latch is also the backedge, so inserting
2356 // post-inc expressions just before the latch is ideal. To reduce live ranges
2357 // it also makes sense to rewrite terminating conditions to use post-inc
2358 // expressions.
2359 //
2360 // If the loop is not rotated then the latch is not a backedge; the latch
2361 // check is done in the loop head. Adding post-inc expressions before the
2362 // latch will cause overlapping live-ranges of pre-inc and post-inc expressions
2363 // in the loop body. In this case we do *not* want to use post-inc expressions
2364 // in the latch check, and we want to insert post-inc expressions before
2365 // the backedge.
2366 BasicBlock *LatchBlock = L->getLoopLatch();
2367 SmallVector<BasicBlock*, 8> ExitingBlocks;
2368 L->getExitingBlocks(ExitingBlocks);
2369 if (llvm::all_of(ExitingBlocks, [&LatchBlock](const BasicBlock *BB) {
2370 return LatchBlock != BB;
2371 })) {
2372 // The backedge doesn't exit the loop; treat this as a head-tested loop.
2373 IVIncInsertPos = LatchBlock->getTerminator();
2374 return;
2375 }
2376
2377 // Otherwise treat this as a rotated loop.
2378 for (BasicBlock *ExitingBlock : ExitingBlocks) {
2379 // Get the terminating condition for the loop if possible. If we
2380 // can, we want to change it to use a post-incremented version of its
2381 // induction variable, to allow coalescing the live ranges for the IV into
2382 // one register value.
2383
2384 BranchInst *TermBr = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
2385 if (!TermBr)
2386 continue;
2387 // FIXME: Overly conservative, termination condition could be an 'or' etc..
2388 if (TermBr->isUnconditional() || !isa<ICmpInst>(TermBr->getCondition()))
2389 continue;
2390
2391 // Search IVUsesByStride to find Cond's IVUse if there is one.
2392 IVStrideUse *CondUse = nullptr;
2393 ICmpInst *Cond = cast<ICmpInst>(TermBr->getCondition());
2394 if (!FindIVUserForCond(Cond, CondUse))
2395 continue;
2396
2397 // If the trip count is computed in terms of a max (due to ScalarEvolution
2398 // being unable to find a sufficient guard, for example), change the loop
2399 // comparison to use SLT or ULT instead of NE.
2400 // One consequence of doing this now is that it disrupts the count-down
2401 // optimization. That's not always a bad thing though, because in such
2402 // cases it may still be worthwhile to avoid a max.
2403 Cond = OptimizeMax(Cond, CondUse);
2404
2405 // If this exiting block dominates the latch block, it may also use
2406 // the post-inc value if it won't be shared with other uses.
2407 // Check for dominance.
2408 if (!DT.dominates(ExitingBlock, LatchBlock))
2409 continue;
2410
2411 // Conservatively avoid trying to use the post-inc value in non-latch
2412 // exits if there may be pre-inc users in intervening blocks.
2413 if (LatchBlock != ExitingBlock)
2414 for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI)
2415 // Test if the use is reachable from the exiting block. This dominator
2416 // query is a conservative approximation of reachability.
2417 if (&*UI != CondUse &&
2418 !DT.properlyDominates(UI->getUser()->getParent(), ExitingBlock)) {
2419 // Conservatively assume there may be reuse if the quotient of their
2420 // strides could be a legal scale.
2421 const SCEV *A = IU.getStride(*CondUse, L);
2422 const SCEV *B = IU.getStride(*UI, L);
2423 if (!A || !B) continue;
2424 if (SE.getTypeSizeInBits(A->getType()) !=
2425 SE.getTypeSizeInBits(B->getType())) {
2426 if (SE.getTypeSizeInBits(A->getType()) >
2427 SE.getTypeSizeInBits(B->getType()))
2428 B = SE.getSignExtendExpr(B, A->getType());
2429 else
2430 A = SE.getSignExtendExpr(A, B->getType());
2431 }
2432 if (const SCEVConstant *D =
2433 dyn_cast_or_null<SCEVConstant>(getExactSDiv(B, A, SE))) {
2434 const ConstantInt *C = D->getValue();
2435 // Stride of one or negative one can have reuse with non-addresses.
2436 if (C->isOne() || C->isMinusOne())
2437 goto decline_post_inc;
2438 // Avoid weird situations.
2439 if (C->getValue().getMinSignedBits() >= 64 ||
2440 C->getValue().isMinSignedValue())
2441 goto decline_post_inc;
2442 // Check for possible scaled-address reuse.
2443 if (isAddressUse(TTI, UI->getUser(), UI->getOperandValToReplace())) {
2444 MemAccessTy AccessTy = getAccessType(
2445 TTI, UI->getUser(), UI->getOperandValToReplace());
2446 int64_t Scale = C->getSExtValue();
2447 if (TTI.isLegalAddressingMode(AccessTy.MemTy, /*BaseGV=*/nullptr,
2448 /*BaseOffset=*/0,
2449 /*HasBaseReg=*/false, Scale,
2450 AccessTy.AddrSpace))
2451 goto decline_post_inc;
2452 Scale = -Scale;
2453 if (TTI.isLegalAddressingMode(AccessTy.MemTy, /*BaseGV=*/nullptr,
2454 /*BaseOffset=*/0,
2455 /*HasBaseReg=*/false, Scale,
2456 AccessTy.AddrSpace))
2457 goto decline_post_inc;
2458 }
2459 }
2460 }
2461
2462 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)
2463 << *Cond << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Change loop exiting icmp to use postinc iv: "
<< *Cond << '\n'; } } while (false)
;
2464
2465 // It's possible for the setcc instruction to be anywhere in the loop, and
2466 // possible for it to have multiple users. If it is not immediately before
2467 // the exiting block branch, move it.
2468 if (&*++BasicBlock::iterator(Cond) != TermBr) {
2469 if (Cond->hasOneUse()) {
2470 Cond->moveBefore(TermBr);
2471 } else {
2472 // Clone the terminating condition and insert into the loopend.
2473 ICmpInst *OldCond = Cond;
2474 Cond = cast<ICmpInst>(Cond->clone());
2475 Cond->setName(L->getHeader()->getName() + ".termcond");
2476 ExitingBlock->getInstList().insert(TermBr->getIterator(), Cond);
2477
2478 // Clone the IVUse, as the old use still exists!
2479 CondUse = &IU.AddUser(Cond, CondUse->getOperandValToReplace());
2480 TermBr->replaceUsesOfWith(OldCond, Cond);
2481 }
2482 }
2483
2484 // If we get to here, we know that we can transform the setcc instruction to
2485 // use the post-incremented version of the IV, allowing us to coalesce the
2486 // live ranges for the IV correctly.
2487 CondUse->transformToPostInc(L);
2488 Changed = true;
2489
2490 PostIncs.insert(Cond);
2491 decline_post_inc:;
2492 }
2493
2494 // Determine an insertion point for the loop induction variable increment. It
2495 // must dominate all the post-inc comparisons we just set up, and it must
2496 // dominate the loop latch edge.
2497 IVIncInsertPos = L->getLoopLatch()->getTerminator();
2498 for (Instruction *Inst : PostIncs) {
2499 BasicBlock *BB =
2500 DT.findNearestCommonDominator(IVIncInsertPos->getParent(),
2501 Inst->getParent());
2502 if (BB == Inst->getParent())
2503 IVIncInsertPos = Inst;
2504 else if (BB != IVIncInsertPos->getParent())
2505 IVIncInsertPos = BB->getTerminator();
2506 }
2507}
2508
2509/// Determine if the given use can accommodate a fixup at the given offset and
2510/// other details. If so, update the use and return true.
2511bool LSRInstance::reconcileNewOffset(LSRUse &LU, int64_t NewOffset,
2512 bool HasBaseReg, LSRUse::KindType Kind,
2513 MemAccessTy AccessTy) {
2514 int64_t NewMinOffset = LU.MinOffset;
2515 int64_t NewMaxOffset = LU.MaxOffset;
2516 MemAccessTy NewAccessTy = AccessTy;
2517
2518 // Check for a mismatched kind. It's tempting to collapse mismatched kinds to
2519 // something conservative, however this can pessimize in the case that one of
2520 // the uses will have all its uses outside the loop, for example.
2521 if (LU.Kind != Kind)
2522 return false;
2523
2524 // Check for a mismatched access type, and fall back conservatively as needed.
2525 // TODO: Be less conservative when the type is similar and can use the same
2526 // addressing modes.
2527 if (Kind == LSRUse::Address) {
2528 if (AccessTy.MemTy != LU.AccessTy.MemTy) {
2529 NewAccessTy = MemAccessTy::getUnknown(AccessTy.MemTy->getContext(),
2530 AccessTy.AddrSpace);
2531 }
2532 }
2533
2534 // Conservatively assume HasBaseReg is true for now.
2535 if (NewOffset < LU.MinOffset) {
2536 if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr,
2537 LU.MaxOffset - NewOffset, HasBaseReg))
2538 return false;
2539 NewMinOffset = NewOffset;
2540 } else if (NewOffset > LU.MaxOffset) {
2541 if (!isAlwaysFoldable(TTI, Kind, NewAccessTy, /*BaseGV=*/nullptr,
2542 NewOffset - LU.MinOffset, HasBaseReg))
2543 return false;
2544 NewMaxOffset = NewOffset;
2545 }
2546
2547 // Update the use.
2548 LU.MinOffset = NewMinOffset;
2549 LU.MaxOffset = NewMaxOffset;
2550 LU.AccessTy = NewAccessTy;
2551 return true;
2552}
2553
2554/// Return an LSRUse index and an offset value for a fixup which needs the given
2555/// expression, with the given kind and optional access type. Either reuse an
2556/// existing use or create a new one, as needed.
2557std::pair<size_t, int64_t> LSRInstance::getUse(const SCEV *&Expr,
2558 LSRUse::KindType Kind,
2559 MemAccessTy AccessTy) {
2560 const SCEV *Copy = Expr;
2561 int64_t Offset = ExtractImmediate(Expr, SE);
2562
2563 // Basic uses can't accept any offset, for example.
2564 if (!isAlwaysFoldable(TTI, Kind, AccessTy, /*BaseGV=*/ nullptr,
2565 Offset, /*HasBaseReg=*/ true)) {
2566 Expr = Copy;
2567 Offset = 0;
2568 }
2569
2570 std::pair<UseMapTy::iterator, bool> P =
2571 UseMap.insert(std::make_pair(LSRUse::SCEVUseKindPair(Expr, Kind), 0));
2572 if (!P.second) {
2573 // A use already existed with this base.
2574 size_t LUIdx = P.first->second;
2575 LSRUse &LU = Uses[LUIdx];
2576 if (reconcileNewOffset(LU, Offset, /*HasBaseReg=*/true, Kind, AccessTy))
2577 // Reuse this use.
2578 return std::make_pair(LUIdx, Offset);
2579 }
2580
2581 // Create a new use.
2582 size_t LUIdx = Uses.size();
2583 P.first->second = LUIdx;
2584 Uses.push_back(LSRUse(Kind, AccessTy));
2585 LSRUse &LU = Uses[LUIdx];
2586
2587 LU.MinOffset = Offset;
2588 LU.MaxOffset = Offset;
2589 return std::make_pair(LUIdx, Offset);
2590}
2591
2592/// Delete the given use from the Uses list.
2593void LSRInstance::DeleteUse(LSRUse &LU, size_t LUIdx) {
2594 if (&LU != &Uses.back())
2595 std::swap(LU, Uses.back());
2596 Uses.pop_back();
2597
2598 // Update RegUses.
2599 RegUses.swapAndDropUse(LUIdx, Uses.size());
2600}
2601
2602/// Look for a use distinct from OrigLU which is has a formula that has the same
2603/// registers as the given formula.
2604LSRUse *
2605LSRInstance::FindUseWithSimilarFormula(const Formula &OrigF,
2606 const LSRUse &OrigLU) {
2607 // Search all uses for the formula. This could be more clever.
2608 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
2609 LSRUse &LU = Uses[LUIdx];
2610 // Check whether this use is close enough to OrigLU, to see whether it's
2611 // worthwhile looking through its formulae.
2612 // Ignore ICmpZero uses because they may contain formulae generated by
2613 // GenerateICmpZeroScales, in which case adding fixup offsets may
2614 // be invalid.
2615 if (&LU != &OrigLU &&
2616 LU.Kind != LSRUse::ICmpZero &&
2617 LU.Kind == OrigLU.Kind && OrigLU.AccessTy == LU.AccessTy &&
2618 LU.WidestFixupType == OrigLU.WidestFixupType &&
2619 LU.HasFormulaWithSameRegs(OrigF)) {
2620 // Scan through this use's formulae.
2621 for (const Formula &F : LU.Formulae) {
2622 // Check to see if this formula has the same registers and symbols
2623 // as OrigF.
2624 if (F.BaseRegs == OrigF.BaseRegs &&
2625 F.ScaledReg == OrigF.ScaledReg &&
2626 F.BaseGV == OrigF.BaseGV &&
2627 F.Scale == OrigF.Scale &&
2628 F.UnfoldedOffset == OrigF.UnfoldedOffset) {
2629 if (F.BaseOffset == 0)
2630 return &LU;
2631 // This is the formula where all the registers and symbols matched;
2632 // there aren't going to be any others. Since we declined it, we
2633 // can skip the rest of the formulae and proceed to the next LSRUse.
2634 break;
2635 }
2636 }
2637 }
2638 }
2639
2640 // Nothing looked good.
2641 return nullptr;
2642}
2643
2644void LSRInstance::CollectInterestingTypesAndFactors() {
2645 SmallSetVector<const SCEV *, 4> Strides;
2646
2647 // Collect interesting types and strides.
2648 SmallVector<const SCEV *, 4> Worklist;
2649 for (const IVStrideUse &U : IU) {
2650 const SCEV *Expr = IU.getExpr(U);
2651
2652 // Collect interesting types.
2653 Types.insert(SE.getEffectiveSCEVType(Expr->getType()));
2654
2655 // Add strides for mentioned loops.
2656 Worklist.push_back(Expr);
2657 do {
2658 const SCEV *S = Worklist.pop_back_val();
2659 if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
2660 if (AR->getLoop() == L)
2661 Strides.insert(AR->getStepRecurrence(SE));
2662 Worklist.push_back(AR->getStart());
2663 } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
2664 Worklist.append(Add->op_begin(), Add->op_end());
2665 }
2666 } while (!Worklist.empty());
2667 }
2668
2669 // Compute interesting factors from the set of interesting strides.
2670 for (SmallSetVector<const SCEV *, 4>::const_iterator
2671 I = Strides.begin(), E = Strides.end(); I != E; ++I)
2672 for (SmallSetVector<const SCEV *, 4>::const_iterator NewStrideIter =
2673 std::next(I); NewStrideIter != E; ++NewStrideIter) {
2674 const SCEV *OldStride = *I;
2675 const SCEV *NewStride = *NewStrideIter;
2676
2677 if (SE.getTypeSizeInBits(OldStride->getType()) !=
2678 SE.getTypeSizeInBits(NewStride->getType())) {
2679 if (SE.getTypeSizeInBits(OldStride->getType()) >
2680 SE.getTypeSizeInBits(NewStride->getType()))
2681 NewStride = SE.getSignExtendExpr(NewStride, OldStride->getType());
2682 else
2683 OldStride = SE.getSignExtendExpr(OldStride, NewStride->getType());
2684 }
2685 if (const SCEVConstant *Factor =
2686 dyn_cast_or_null<SCEVConstant>(getExactSDiv(NewStride, OldStride,
2687 SE, true))) {
2688 if (Factor->getAPInt().getMinSignedBits() <= 64)
2689 Factors.insert(Factor->getAPInt().getSExtValue());
2690 } else if (const SCEVConstant *Factor =
2691 dyn_cast_or_null<SCEVConstant>(getExactSDiv(OldStride,
2692 NewStride,
2693 SE, true))) {
2694 if (Factor->getAPInt().getMinSignedBits() <= 64)
2695 Factors.insert(Factor->getAPInt().getSExtValue());
2696 }
2697 }
2698
2699 // If all uses use the same type, don't bother looking for truncation-based
2700 // reuse.
2701 if (Types.size() == 1)
2702 Types.clear();
2703
2704 LLVM_DEBUG(print_factors_and_types(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { print_factors_and_types(dbgs()); } } while
(false)
;
2705}
2706
2707/// Helper for CollectChains that finds an IV operand (computed by an AddRec in
2708/// this loop) within [OI,OE) or returns OE. If IVUsers mapped Instructions to
2709/// IVStrideUses, we could partially skip this.
2710static User::op_iterator
2711findIVOperand(User::op_iterator OI, User::op_iterator OE,
2712 Loop *L, ScalarEvolution &SE) {
2713 for(; OI != OE; ++OI) {
2714 if (Instruction *Oper = dyn_cast<Instruction>(*OI)) {
2715 if (!SE.isSCEVable(Oper->getType()))
2716 continue;
2717
2718 if (const SCEVAddRecExpr *AR =
2719 dyn_cast<SCEVAddRecExpr>(SE.getSCEV(Oper))) {
2720 if (AR->getLoop() == L)
2721 break;
2722 }
2723 }
2724 }
2725 return OI;
2726}
2727
2728/// IVChain logic must consistently peek base TruncInst operands, so wrap it in
2729/// a convenient helper.
2730static Value *getWideOperand(Value *Oper) {
2731 if (TruncInst *Trunc = dyn_cast<TruncInst>(Oper))
2732 return Trunc->getOperand(0);
2733 return Oper;
2734}
2735
2736/// Return true if we allow an IV chain to include both types.
2737static bool isCompatibleIVType(Value *LVal, Value *RVal) {
2738 Type *LType = LVal->getType();
2739 Type *RType = RVal->getType();
2740 return (LType == RType) || (LType->isPointerTy() && RType->isPointerTy() &&
2741 // Different address spaces means (possibly)
2742 // different types of the pointer implementation,
2743 // e.g. i16 vs i32 so disallow that.
2744 (LType->getPointerAddressSpace() ==
2745 RType->getPointerAddressSpace()));
2746}
2747
2748/// Return an approximation of this SCEV expression's "base", or NULL for any
2749/// constant. Returning the expression itself is conservative. Returning a
2750/// deeper subexpression is more precise and valid as long as it isn't less
2751/// complex than another subexpression. For expressions involving multiple
2752/// unscaled values, we need to return the pointer-type SCEVUnknown. This avoids
2753/// forming chains across objects, such as: PrevOper==a[i], IVOper==b[i],
2754/// IVInc==b-a.
2755///
2756/// Since SCEVUnknown is the rightmost type, and pointers are the rightmost
2757/// SCEVUnknown, we simply return the rightmost SCEV operand.
2758static const SCEV *getExprBase(const SCEV *S) {
2759 switch (S->getSCEVType()) {
2760 default: // uncluding scUnknown.
2761 return S;
2762 case scConstant:
2763 return nullptr;
2764 case scTruncate:
2765 return getExprBase(cast<SCEVTruncateExpr>(S)->getOperand());
2766 case scZeroExtend:
2767 return getExprBase(cast<SCEVZeroExtendExpr>(S)->getOperand());
2768 case scSignExtend:
2769 return getExprBase(cast<SCEVSignExtendExpr>(S)->getOperand());
2770 case scAddExpr: {
2771 // Skip over scaled operands (scMulExpr) to follow add operands as long as
2772 // there's nothing more complex.
2773 // FIXME: not sure if we want to recognize negation.
2774 const SCEVAddExpr *Add = cast<SCEVAddExpr>(S);
2775 for (std::reverse_iterator<SCEVAddExpr::op_iterator> I(Add->op_end()),
2776 E(Add->op_begin()); I != E; ++I) {
2777 const SCEV *SubExpr = *I;
2778 if (SubExpr->getSCEVType() == scAddExpr)
2779 return getExprBase(SubExpr);
2780
2781 if (SubExpr->getSCEVType() != scMulExpr)
2782 return SubExpr;
2783 }
2784 return S; // all operands are scaled, be conservative.
2785 }
2786 case scAddRecExpr:
2787 return getExprBase(cast<SCEVAddRecExpr>(S)->getStart());
2788 }
2789}
2790
2791/// Return true if the chain increment is profitable to expand into a loop
2792/// invariant value, which may require its own register. A profitable chain
2793/// increment will be an offset relative to the same base. We allow such offsets
2794/// to potentially be used as chain increment as long as it's not obviously
2795/// expensive to expand using real instructions.
2796bool IVChain::isProfitableIncrement(const SCEV *OperExpr,
2797 const SCEV *IncExpr,
2798 ScalarEvolution &SE) {
2799 // Aggressively form chains when -stress-ivchain.
2800 if (StressIVChain)
2801 return true;
2802
2803 // Do not replace a constant offset from IV head with a nonconstant IV
2804 // increment.
2805 if (!isa<SCEVConstant>(IncExpr)) {
2806 const SCEV *HeadExpr = SE.getSCEV(getWideOperand(Incs[0].IVOperand));
2807 if (isa<SCEVConstant>(SE.getMinusSCEV(OperExpr, HeadExpr)))
2808 return false;
2809 }
2810
2811 SmallPtrSet<const SCEV*, 8> Processed;
2812 return !isHighCostExpansion(IncExpr, Processed, SE);
2813}
2814
2815/// Return true if the number of registers needed for the chain is estimated to
2816/// be less than the number required for the individual IV users. First prohibit
2817/// any IV users that keep the IV live across increments (the Users set should
2818/// be empty). Next count the number and type of increments in the chain.
2819///
2820/// Chaining IVs can lead to considerable code bloat if ISEL doesn't
2821/// effectively use postinc addressing modes. Only consider it profitable it the
2822/// increments can be computed in fewer registers when chained.
2823///
2824/// TODO: Consider IVInc free if it's already used in another chains.
2825static bool isProfitableChain(IVChain &Chain,
2826 SmallPtrSetImpl<Instruction *> &Users,
2827 ScalarEvolution &SE,
2828 const TargetTransformInfo &TTI) {
2829 if (StressIVChain)
2830 return true;
2831
2832 if (!Chain.hasIncs())
2833 return false;
2834
2835 if (!Users.empty()) {
2836 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)
2837 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)
2838 : 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)
;
2839 return false;
2840 }
2841 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 2841, __PRETTY_FUNCTION__))
;
2842
2843 // The chain itself may require a register, so intialize cost to 1.
2844 int cost = 1;
2845
2846 // A complete chain likely eliminates the need for keeping the original IV in
2847 // a register. LSR does not currently know how to form a complete chain unless
2848 // the header phi already exists.
2849 if (isa<PHINode>(Chain.tailUserInst())
2850 && SE.getSCEV(Chain.tailUserInst()) == Chain.Incs[0].IncExpr) {
2851 --cost;
2852 }
2853 const SCEV *LastIncExpr = nullptr;
2854 unsigned NumConstIncrements = 0;
2855 unsigned NumVarIncrements = 0;
2856 unsigned NumReusedIncrements = 0;
2857
2858 if (TTI.isProfitableLSRChainElement(Chain.Incs[0].UserInst))
2859 return true;
2860
2861 for (const IVInc &Inc : Chain) {
2862 if (TTI.isProfitableLSRChainElement(Inc.UserInst))
2863 return true;
2864
2865 if (Inc.IncExpr->isZero())
2866 continue;
2867
2868 // Incrementing by zero or some constant is neutral. We assume constants can
2869 // be folded into an addressing mode or an add's immediate operand.
2870 if (isa<SCEVConstant>(Inc.IncExpr)) {
2871 ++NumConstIncrements;
2872 continue;
2873 }
2874
2875 if (Inc.IncExpr == LastIncExpr)
2876 ++NumReusedIncrements;
2877 else
2878 ++NumVarIncrements;
2879
2880 LastIncExpr = Inc.IncExpr;
2881 }
2882 // An IV chain with a single increment is handled by LSR's postinc
2883 // uses. However, a chain with multiple increments requires keeping the IV's
2884 // value live longer than it needs to be if chained.
2885 if (NumConstIncrements > 1)
2886 --cost;
2887
2888 // Materializing increment expressions in the preheader that didn't exist in
2889 // the original code may cost a register. For example, sign-extended array
2890 // indices can produce ridiculous increments like this:
2891 // IV + ((sext i32 (2 * %s) to i64) + (-1 * (sext i32 %s to i64)))
2892 cost += NumVarIncrements;
2893
2894 // Reusing variable increments likely saves a register to hold the multiple of
2895 // the stride.
2896 cost -= NumReusedIncrements;
2897
2898 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)
2899 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Chain: " << *Chain.
Incs[0].UserInst << " Cost: " << cost << "\n"
; } } while (false)
;
2900
2901 return cost < 0;
2902}
2903
2904/// Add this IV user to an existing chain or make it the head of a new chain.
2905void LSRInstance::ChainInstruction(Instruction *UserInst, Instruction *IVOper,
2906 SmallVectorImpl<ChainUsers> &ChainUsersVec) {
2907 // When IVs are used as types of varying widths, they are generally converted
2908 // to a wider type with some uses remaining narrow under a (free) trunc.
2909 Value *const NextIV = getWideOperand(IVOper);
2910 const SCEV *const OperExpr = SE.getSCEV(NextIV);
2911 const SCEV *const OperExprBase = getExprBase(OperExpr);
2912
2913 // Visit all existing chains. Check if its IVOper can be computed as a
2914 // profitable loop invariant increment from the last link in the Chain.
2915 unsigned ChainIdx = 0, NChains = IVChainVec.size();
2916 const SCEV *LastIncExpr = nullptr;
2917 for (; ChainIdx < NChains; ++ChainIdx) {
2918 IVChain &Chain = IVChainVec[ChainIdx];
2919
2920 // Prune the solution space aggressively by checking that both IV operands
2921 // are expressions that operate on the same unscaled SCEVUnknown. This
2922 // "base" will be canceled by the subsequent getMinusSCEV call. Checking
2923 // first avoids creating extra SCEV expressions.
2924 if (!StressIVChain && Chain.ExprBase != OperExprBase)
2925 continue;
2926
2927 Value *PrevIV = getWideOperand(Chain.Incs.back().IVOperand);
2928 if (!isCompatibleIVType(PrevIV, NextIV))
2929 continue;
2930
2931 // A phi node terminates a chain.
2932 if (isa<PHINode>(UserInst) && isa<PHINode>(Chain.tailUserInst()))
2933 continue;
2934
2935 // The increment must be loop-invariant so it can be kept in a register.
2936 const SCEV *PrevExpr = SE.getSCEV(PrevIV);
2937 const SCEV *IncExpr = SE.getMinusSCEV(OperExpr, PrevExpr);
2938 if (!SE.isLoopInvariant(IncExpr, L))
2939 continue;
2940
2941 if (Chain.isProfitableIncrement(OperExpr, IncExpr, SE)) {
2942 LastIncExpr = IncExpr;
2943 break;
2944 }
2945 }
2946 // If we haven't found a chain, create a new one, unless we hit the max. Don't
2947 // bother for phi nodes, because they must be last in the chain.
2948 if (ChainIdx == NChains) {
2949 if (isa<PHINode>(UserInst))
2950 return;
2951 if (NChains >= MaxChains && !StressIVChain) {
2952 LLVM_DEBUG(dbgs() << "IV Chain Limit\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain Limit\n"; } } while
(false)
;
2953 return;
2954 }
2955 LastIncExpr = OperExpr;
2956 // IVUsers may have skipped over sign/zero extensions. We don't currently
2957 // attempt to form chains involving extensions unless they can be hoisted
2958 // into this loop's AddRec.
2959 if (!isa<SCEVAddRecExpr>(LastIncExpr))
2960 return;
2961 ++NChains;
2962 IVChainVec.push_back(IVChain(IVInc(UserInst, IVOper, LastIncExpr),
2963 OperExprBase));
2964 ChainUsersVec.resize(NChains);
2965 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)
2966 << ") IV=" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Head: (" << *UserInst << ") IV=" <<
*LastIncExpr << "\n"; } } while (false)
;
2967 } else {
2968 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)
2969 << ") IV+" << *LastIncExpr << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "IV Chain#" << ChainIdx
<< " Inc: (" << *UserInst << ") IV+" <<
*LastIncExpr << "\n"; } } while (false)
;
2970 // Add this IV user to the end of the chain.
2971 IVChainVec[ChainIdx].add(IVInc(UserInst, IVOper, LastIncExpr));
2972 }
2973 IVChain &Chain = IVChainVec[ChainIdx];
2974
2975 SmallPtrSet<Instruction*,4> &NearUsers = ChainUsersVec[ChainIdx].NearUsers;
2976 // This chain's NearUsers become FarUsers.
2977 if (!LastIncExpr->isZero()) {
2978 ChainUsersVec[ChainIdx].FarUsers.insert(NearUsers.begin(),
2979 NearUsers.end());
2980 NearUsers.clear();
2981 }
2982
2983 // All other uses of IVOperand become near uses of the chain.
2984 // We currently ignore intermediate values within SCEV expressions, assuming
2985 // they will eventually be used be the current chain, or can be computed
2986 // from one of the chain increments. To be more precise we could
2987 // transitively follow its user and only add leaf IV users to the set.
2988 for (User *U : IVOper->users()) {
2989 Instruction *OtherUse = dyn_cast<Instruction>(U);
2990 if (!OtherUse)
2991 continue;
2992 // Uses in the chain will no longer be uses if the chain is formed.
2993 // Include the head of the chain in this iteration (not Chain.begin()).
2994 IVChain::const_iterator IncIter = Chain.Incs.begin();
2995 IVChain::const_iterator IncEnd = Chain.Incs.end();
2996 for( ; IncIter != IncEnd; ++IncIter) {
2997 if (IncIter->UserInst == OtherUse)
2998 break;
2999 }
3000 if (IncIter != IncEnd)
3001 continue;
3002
3003 if (SE.isSCEVable(OtherUse->getType())
3004 && !isa<SCEVUnknown>(SE.getSCEV(OtherUse))
3005 && IU.isIVUserOrOperand(OtherUse)) {
3006 continue;
3007 }
3008 NearUsers.insert(OtherUse);
3009 }
3010
3011 // Since this user is part of the chain, it's no longer considered a use
3012 // of the chain.
3013 ChainUsersVec[ChainIdx].FarUsers.erase(UserInst);
3014}
3015
3016/// Populate the vector of Chains.
3017///
3018/// This decreases ILP at the architecture level. Targets with ample registers,
3019/// multiple memory ports, and no register renaming probably don't want
3020/// this. However, such targets should probably disable LSR altogether.
3021///
3022/// The job of LSR is to make a reasonable choice of induction variables across
3023/// the loop. Subsequent passes can easily "unchain" computation exposing more
3024/// ILP *within the loop* if the target wants it.
3025///
3026/// Finding the best IV chain is potentially a scheduling problem. Since LSR
3027/// will not reorder memory operations, it will recognize this as a chain, but
3028/// will generate redundant IV increments. Ideally this would be corrected later
3029/// by a smart scheduler:
3030/// = A[i]
3031/// = A[i+x]
3032/// A[i] =
3033/// A[i+x] =
3034///
3035/// TODO: Walk the entire domtree within this loop, not just the path to the
3036/// loop latch. This will discover chains on side paths, but requires
3037/// maintaining multiple copies of the Chains state.
3038void LSRInstance::CollectChains() {
3039 LLVM_DEBUG(dbgs() << "Collecting IV Chains.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Collecting IV Chains.\n";
} } while (false)
;
3040 SmallVector<ChainUsers, 8> ChainUsersVec;
3041
3042 SmallVector<BasicBlock *,8> LatchPath;
3043 BasicBlock *LoopHeader = L->getHeader();
3044 for (DomTreeNode *Rung = DT.getNode(L->getLoopLatch());
3045 Rung->getBlock() != LoopHeader; Rung = Rung->getIDom()) {
3046 LatchPath.push_back(Rung->getBlock());
3047 }
3048 LatchPath.push_back(LoopHeader);
3049
3050 // Walk the instruction stream from the loop header to the loop latch.
3051 for (BasicBlock *BB : reverse(LatchPath)) {
3052 for (Instruction &I : *BB) {
3053 // Skip instructions that weren't seen by IVUsers analysis.
3054 if (isa<PHINode>(I) || !IU.isIVUserOrOperand(&I))
3055 continue;
3056
3057 // Ignore users that are part of a SCEV expression. This way we only
3058 // consider leaf IV Users. This effectively rediscovers a portion of
3059 // IVUsers analysis but in program order this time.
3060 if (SE.isSCEVable(I.getType()) && !isa<SCEVUnknown>(SE.getSCEV(&I)))
3061 continue;
3062
3063 // Remove this instruction from any NearUsers set it may be in.
3064 for (unsigned ChainIdx = 0, NChains = IVChainVec.size();
3065 ChainIdx < NChains; ++ChainIdx) {
3066 ChainUsersVec[ChainIdx].NearUsers.erase(&I);
3067 }
3068 // Search for operands that can be chained.
3069 SmallPtrSet<Instruction*, 4> UniqueOperands;
3070 User::op_iterator IVOpEnd = I.op_end();
3071 User::op_iterator IVOpIter = findIVOperand(I.op_begin(), IVOpEnd, L, SE);
3072 while (IVOpIter != IVOpEnd) {
3073 Instruction *IVOpInst = cast<Instruction>(*IVOpIter);
3074 if (UniqueOperands.insert(IVOpInst).second)
3075 ChainInstruction(&I, IVOpInst, ChainUsersVec);
3076 IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE);
3077 }
3078 } // Continue walking down the instructions.
3079 } // Continue walking down the domtree.
3080 // Visit phi backedges to determine if the chain can generate the IV postinc.
3081 for (PHINode &PN : L->getHeader()->phis()) {
3082 if (!SE.isSCEVable(PN.getType()))
3083 continue;
3084
3085 Instruction *IncV =
3086 dyn_cast<Instruction>(PN.getIncomingValueForBlock(L->getLoopLatch()));
3087 if (IncV)
3088 ChainInstruction(&PN, IncV, ChainUsersVec);
3089 }
3090 // Remove any unprofitable chains.
3091 unsigned ChainIdx = 0;
3092 for (unsigned UsersIdx = 0, NChains = IVChainVec.size();
3093 UsersIdx < NChains; ++UsersIdx) {
3094 if (!isProfitableChain(IVChainVec[UsersIdx],
3095 ChainUsersVec[UsersIdx].FarUsers, SE, TTI))
3096 continue;
3097 // Preserve the chain at UsesIdx.
3098 if (ChainIdx != UsersIdx)
3099 IVChainVec[ChainIdx] = IVChainVec[UsersIdx];
3100 FinalizeChain(IVChainVec[ChainIdx]);
3101 ++ChainIdx;
3102 }
3103 IVChainVec.resize(ChainIdx);
3104}
3105
3106void LSRInstance::FinalizeChain(IVChain &Chain) {
3107 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3107, __PRETTY_FUNCTION__))
;
3108 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)
;
3109
3110 for (const IVInc &Inc : Chain) {
3111 LLVM_DEBUG(dbgs() << " Inc: " << *Inc.UserInst << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Inc: " << *
Inc.UserInst << "\n"; } } while (false)
;
3112 auto UseI = find(Inc.UserInst->operands(), Inc.IVOperand);
3113 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3113, __PRETTY_FUNCTION__))
;
3114 IVIncSet.insert(UseI);
3115 }
3116}
3117
3118/// Return true if the IVInc can be folded into an addressing mode.
3119static bool canFoldIVIncExpr(const SCEV *IncExpr, Instruction *UserInst,
3120 Value *Operand, const TargetTransformInfo &TTI) {
3121 const SCEVConstant *IncConst = dyn_cast<SCEVConstant>(IncExpr);
3122 if (!IncConst || !isAddressUse(TTI, UserInst, Operand))
3123 return false;
3124
3125 if (IncConst->getAPInt().getMinSignedBits() > 64)
3126 return false;
3127
3128 MemAccessTy AccessTy = getAccessType(TTI, UserInst, Operand);
3129 int64_t IncOffset = IncConst->getValue()->getSExtValue();
3130 if (!isAlwaysFoldable(TTI, LSRUse::Address, AccessTy, /*BaseGV=*/nullptr,
3131 IncOffset, /*HasBaseReg=*/false))
3132 return false;
3133
3134 return true;
3135}
3136
3137/// Generate an add or subtract for each IVInc in a chain to materialize the IV
3138/// user's operand from the previous IV user's operand.
3139void LSRInstance::GenerateIVChain(const IVChain &Chain, SCEVExpander &Rewriter,
3140 SmallVectorImpl<WeakTrackingVH> &DeadInsts) {
3141 // Find the new IVOperand for the head of the chain. It may have been replaced
3142 // by LSR.
3143 const IVInc &Head = Chain.Incs[0];
3144 User::op_iterator IVOpEnd = Head.UserInst->op_end();
3145 // findIVOperand returns IVOpEnd if it can no longer find a valid IV user.
3146 User::op_iterator IVOpIter = findIVOperand(Head.UserInst->op_begin(),
3147 IVOpEnd, L, SE);
3148 Value *IVSrc = nullptr;
3149 while (IVOpIter != IVOpEnd) {
3150 IVSrc = getWideOperand(*IVOpIter);
3151
3152 // If this operand computes the expression that the chain needs, we may use
3153 // it. (Check this after setting IVSrc which is used below.)
3154 //
3155 // Note that if Head.IncExpr is wider than IVSrc, then this phi is too
3156 // narrow for the chain, so we can no longer use it. We do allow using a
3157 // wider phi, assuming the LSR checked for free truncation. In that case we
3158 // should already have a truncate on this operand such that
3159 // getSCEV(IVSrc) == IncExpr.
3160 if (SE.getSCEV(*IVOpIter) == Head.IncExpr
3161 || SE.getSCEV(IVSrc) == Head.IncExpr) {
3162 break;
3163 }
3164 IVOpIter = findIVOperand(std::next(IVOpIter), IVOpEnd, L, SE);
3165 }
3166 if (IVOpIter == IVOpEnd) {
3167 // Gracefully give up on this chain.
3168 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)
;
3169 return;
3170 }
3171 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3171, __PRETTY_FUNCTION__))
;
3172
3173 LLVM_DEBUG(dbgs() << "Generate chain at: " << *IVSrc << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Generate chain at: " <<
*IVSrc << "\n"; } } while (false)
;
3174 Type *IVTy = IVSrc->getType();
3175 Type *IntTy = SE.getEffectiveSCEVType(IVTy);
3176 const SCEV *LeftOverExpr = nullptr;
3177 for (const IVInc &Inc : Chain) {
3178 Instruction *InsertPt = Inc.UserInst;
3179 if (isa<PHINode>(InsertPt))
3180 InsertPt = L->getLoopLatch()->getTerminator();
3181
3182 // IVOper will replace the current IV User's operand. IVSrc is the IV
3183 // value currently held in a register.
3184 Value *IVOper = IVSrc;
3185 if (!Inc.IncExpr->isZero()) {
3186 // IncExpr was the result of subtraction of two narrow values, so must
3187 // be signed.
3188 const SCEV *IncExpr = SE.getNoopOrSignExtend(Inc.IncExpr, IntTy);
3189 LeftOverExpr = LeftOverExpr ?
3190 SE.getAddExpr(LeftOverExpr, IncExpr) : IncExpr;
3191 }
3192 if (LeftOverExpr && !LeftOverExpr->isZero()) {
3193 // Expand the IV increment.
3194 Rewriter.clearPostInc();
3195 Value *IncV = Rewriter.expandCodeFor(LeftOverExpr, IntTy, InsertPt);
3196 const SCEV *IVOperExpr = SE.getAddExpr(SE.getUnknown(IVSrc),
3197 SE.getUnknown(IncV));
3198 IVOper = Rewriter.expandCodeFor(IVOperExpr, IVTy, InsertPt);
3199
3200 // If an IV increment can't be folded, use it as the next IV value.
3201 if (!canFoldIVIncExpr(LeftOverExpr, Inc.UserInst, Inc.IVOperand, TTI)) {
3202 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3202, __PRETTY_FUNCTION__))
;
3203 IVSrc = IVOper;
3204 LeftOverExpr = nullptr;
3205 }
3206 }
3207 Type *OperTy = Inc.IVOperand->getType();
3208 if (IVTy != OperTy) {
3209 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3210, __PRETTY_FUNCTION__))
3210 "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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3210, __PRETTY_FUNCTION__))
;
3211 IRBuilder<> Builder(InsertPt);
3212 IVOper = Builder.CreateTruncOrBitCast(IVOper, OperTy, "lsr.chain");
3213 }
3214 Inc.UserInst->replaceUsesOfWith(Inc.IVOperand, IVOper);
3215 if (auto *OperandIsInstr = dyn_cast<Instruction>(Inc.IVOperand))
3216 DeadInsts.emplace_back(OperandIsInstr);
3217 }
3218 // If LSR created a new, wider phi, we may also replace its postinc. We only
3219 // do this if we also found a wide value for the head of the chain.
3220 if (isa<PHINode>(Chain.tailUserInst())) {
3221 for (PHINode &Phi : L->getHeader()->phis()) {
3222 if (!isCompatibleIVType(&Phi, IVSrc))
3223 continue;
3224 Instruction *PostIncV = dyn_cast<Instruction>(
3225 Phi.getIncomingValueForBlock(L->getLoopLatch()));
3226 if (!PostIncV || (SE.getSCEV(PostIncV) != SE.getSCEV(IVSrc)))
3227 continue;
3228 Value *IVOper = IVSrc;
3229 Type *PostIncTy = PostIncV->getType();
3230 if (IVTy != PostIncTy) {
3231 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3231, __PRETTY_FUNCTION__))
;
3232 IRBuilder<> Builder(L->getLoopLatch()->getTerminator());
3233 Builder.SetCurrentDebugLocation(PostIncV->getDebugLoc());
3234 IVOper = Builder.CreatePointerCast(IVSrc, PostIncTy, "lsr.chain");
3235 }
3236 Phi.replaceUsesOfWith(PostIncV, IVOper);
3237 DeadInsts.emplace_back(PostIncV);
3238 }
3239 }
3240}
3241
3242void LSRInstance::CollectFixupsAndInitialFormulae() {
3243 BranchInst *ExitBranch = nullptr;
3244 bool SaveCmp = TTI.canSaveCmp(L, &ExitBranch, &SE, &LI, &DT, &AC, &TLI);
3245
3246 for (const IVStrideUse &U : IU) {
3247 Instruction *UserInst = U.getUser();
3248 // Skip IV users that are part of profitable IV Chains.
3249 User::op_iterator UseI =
3250 find(UserInst->operands(), U.getOperandValToReplace());
3251 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3251, __PRETTY_FUNCTION__))
;
3252 if (IVIncSet.count(UseI)) {
3253 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)
;
3254 continue;
3255 }
3256
3257 LSRUse::KindType Kind = LSRUse::Basic;
3258 MemAccessTy AccessTy;
3259 if (isAddressUse(TTI, UserInst, U.getOperandValToReplace())) {
3260 Kind = LSRUse::Address;
3261 AccessTy = getAccessType(TTI, UserInst, U.getOperandValToReplace());
3262 }
3263
3264 const SCEV *S = IU.getExpr(U);
3265 PostIncLoopSet TmpPostIncLoops = U.getPostIncLoops();
3266
3267 // Equality (== and !=) ICmps are special. We can rewrite (i == N) as
3268 // (N - i == 0), and this allows (N - i) to be the expression that we work
3269 // with rather than just N or i, so we can consider the register
3270 // requirements for both N and i at the same time. Limiting this code to
3271 // equality icmps is not a problem because all interesting loops use
3272 // equality icmps, thanks to IndVarSimplify.
3273 if (ICmpInst *CI = dyn_cast<ICmpInst>(UserInst)) {
3274 // If CI can be saved in some target, like replaced inside hardware loop
3275 // in PowerPC, no need to generate initial formulae for it.
3276 if (SaveCmp && CI == dyn_cast<ICmpInst>(ExitBranch->getCondition()))
3277 continue;
3278 if (CI->isEquality()) {
3279 // Swap the operands if needed to put the OperandValToReplace on the
3280 // left, for consistency.
3281 Value *NV = CI->getOperand(1);
3282 if (NV == U.getOperandValToReplace()) {
3283 CI->setOperand(1, CI->getOperand(0));
3284 CI->setOperand(0, NV);
3285 NV = CI->getOperand(1);
3286 Changed = true;
3287 }
3288
3289 // x == y --> x - y == 0
3290 const SCEV *N = SE.getSCEV(NV);
3291 if (SE.isLoopInvariant(N, L) && isSafeToExpand(N, SE)) {
3292 // S is normalized, so normalize N before folding it into S
3293 // to keep the result normalized.
3294 N = normalizeForPostIncUse(N, TmpPostIncLoops, SE);
3295 Kind = LSRUse::ICmpZero;
3296 S = SE.getMinusSCEV(N, S);
3297 }
3298
3299 // -1 and the negations of all interesting strides (except the negation
3300 // of -1) are now also interesting.
3301 for (size_t i = 0, e = Factors.size(); i != e; ++i)
3302 if (Factors[i] != -1)
3303 Factors.insert(-(uint64_t)Factors[i]);
3304 Factors.insert(-1);
3305 }
3306 }
3307
3308 // Get or create an LSRUse.
3309 std::pair<size_t, int64_t> P = getUse(S, Kind, AccessTy);
3310 size_t LUIdx = P.first;
3311 int64_t Offset = P.second;
3312 LSRUse &LU = Uses[LUIdx];
3313
3314 // Record the fixup.
3315 LSRFixup &LF = LU.getNewFixup();
3316 LF.UserInst = UserInst;
3317 LF.OperandValToReplace = U.getOperandValToReplace();
3318 LF.PostIncLoops = TmpPostIncLoops;
3319 LF.Offset = Offset;
3320 LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L);
3321
3322 if (!LU.WidestFixupType ||
3323 SE.getTypeSizeInBits(LU.WidestFixupType) <
3324 SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))
3325 LU.WidestFixupType = LF.OperandValToReplace->getType();
3326
3327 // If this is the first use of this LSRUse, give it a formula.
3328 if (LU.Formulae.empty()) {
3329 InsertInitialFormula(S, LU, LUIdx);
3330 CountRegisters(LU.Formulae.back(), LUIdx);
3331 }
3332 }
3333
3334 LLVM_DEBUG(print_fixups(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { print_fixups(dbgs()); } } while (false)
;
3335}
3336
3337/// Insert a formula for the given expression into the given use, separating out
3338/// loop-variant portions from loop-invariant and loop-computable portions.
3339void
3340LSRInstance::InsertInitialFormula(const SCEV *S, LSRUse &LU, size_t LUIdx) {
3341 // Mark uses whose expressions cannot be expanded.
3342 if (!isSafeToExpand(S, SE))
3343 LU.RigidFormula = true;
3344
3345 Formula F;
3346 F.initialMatch(S, L, SE);
3347 bool Inserted = InsertFormula(LU, LUIdx, F);
3348 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3348, __PRETTY_FUNCTION__))
; (void)Inserted;
3349}
3350
3351/// Insert a simple single-register formula for the given expression into the
3352/// given use.
3353void
3354LSRInstance::InsertSupplementalFormula(const SCEV *S,
3355 LSRUse &LU, size_t LUIdx) {
3356 Formula F;
3357 F.BaseRegs.push_back(S);
3358 F.HasBaseReg = true;
3359 bool Inserted = InsertFormula(LU, LUIdx, F);
3360 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3360, __PRETTY_FUNCTION__))
; (void)Inserted;
3361}
3362
3363/// Note which registers are used by the given formula, updating RegUses.
3364void LSRInstance::CountRegisters(const Formula &F, size_t LUIdx) {
3365 if (F.ScaledReg)
3366 RegUses.countRegister(F.ScaledReg, LUIdx);
3367 for (const SCEV *BaseReg : F.BaseRegs)
3368 RegUses.countRegister(BaseReg, LUIdx);
3369}
3370
3371/// If the given formula has not yet been inserted, add it to the list, and
3372/// return true. Return false otherwise.
3373bool LSRInstance::InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F) {
3374 // Do not insert formula that we will not be able to expand.
3375 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3376, __PRETTY_FUNCTION__))
3376 "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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3376, __PRETTY_FUNCTION__))
;
3377
3378 if (!LU.InsertFormula(F, *L))
3379 return false;
3380
3381 CountRegisters(F, LUIdx);
3382 return true;
3383}
3384
3385/// Check for other uses of loop-invariant values which we're tracking. These
3386/// other uses will pin these values in registers, making them less profitable
3387/// for elimination.
3388/// TODO: This currently misses non-constant addrec step registers.
3389/// TODO: Should this give more weight to users inside the loop?
3390void
3391LSRInstance::CollectLoopInvariantFixupsAndFormulae() {
3392 SmallVector<const SCEV *, 8> Worklist(RegUses.begin(), RegUses.end());
3393 SmallPtrSet<const SCEV *, 32> Visited;
3394
3395 while (!Worklist.empty()) {
3396 const SCEV *S = Worklist.pop_back_val();
3397
3398 // Don't process the same SCEV twice
3399 if (!Visited.insert(S).second)
3400 continue;
3401
3402 if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S))
3403 Worklist.append(N->op_begin(), N->op_end());
3404 else if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S))
3405 Worklist.push_back(C->getOperand());
3406 else if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
3407 Worklist.push_back(D->getLHS());
3408 Worklist.push_back(D->getRHS());
3409 } else if (const SCEVUnknown *US = dyn_cast<SCEVUnknown>(S)) {
3410 const Value *V = US->getValue();
3411 if (const Instruction *Inst = dyn_cast<Instruction>(V)) {
3412 // Look for instructions defined outside the loop.
3413 if (L->contains(Inst)) continue;
3414 } else if (isa<UndefValue>(V))
3415 // Undef doesn't have a live range, so it doesn't matter.
3416 continue;
3417 for (const Use &U : V->uses()) {
3418 const Instruction *UserInst = dyn_cast<Instruction>(U.getUser());
3419 // Ignore non-instructions.
3420 if (!UserInst)
3421 continue;
3422 // Ignore instructions in other functions (as can happen with
3423 // Constants).
3424 if (UserInst->getParent()->getParent() != L->getHeader()->getParent())
3425 continue;
3426 // Ignore instructions not dominated by the loop.
3427 const BasicBlock *UseBB = !isa<PHINode>(UserInst) ?
3428 UserInst->getParent() :
3429 cast<PHINode>(UserInst)->getIncomingBlock(
3430 PHINode::getIncomingValueNumForOperand(U.getOperandNo()));
3431 if (!DT.dominates(L->getHeader(), UseBB))
3432 continue;
3433 // Don't bother if the instruction is in a BB which ends in an EHPad.
3434 if (UseBB->getTerminator()->isEHPad())
3435 continue;
3436 // Don't bother rewriting PHIs in catchswitch blocks.
3437 if (isa<CatchSwitchInst>(UserInst->getParent()->getTerminator()))
3438 continue;
3439 // Ignore uses which are part of other SCEV expressions, to avoid
3440 // analyzing them multiple times.
3441 if (SE.isSCEVable(UserInst->getType())) {
3442 const SCEV *UserS = SE.getSCEV(const_cast<Instruction *>(UserInst));
3443 // If the user is a no-op, look through to its uses.
3444 if (!isa<SCEVUnknown>(UserS))
3445 continue;
3446 if (UserS == US) {
3447 Worklist.push_back(
3448 SE.getUnknown(const_cast<Instruction *>(UserInst)));
3449 continue;
3450 }
3451 }
3452 // Ignore icmp instructions which are already being analyzed.
3453 if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UserInst)) {
3454 unsigned OtherIdx = !U.getOperandNo();
3455 Value *OtherOp = const_cast<Value *>(ICI->getOperand(OtherIdx));
3456 if (SE.hasComputableLoopEvolution(SE.getSCEV(OtherOp), L))
3457 continue;
3458 }
3459
3460 std::pair<size_t, int64_t> P = getUse(
3461 S, LSRUse::Basic, MemAccessTy());
3462 size_t LUIdx = P.first;
3463 int64_t Offset = P.second;
3464 LSRUse &LU = Uses[LUIdx];
3465 LSRFixup &LF = LU.getNewFixup();
3466 LF.UserInst = const_cast<Instruction *>(UserInst);
3467 LF.OperandValToReplace = U;
3468 LF.Offset = Offset;
3469 LU.AllFixupsOutsideLoop &= LF.isUseFullyOutsideLoop(L);
3470 if (!LU.WidestFixupType ||
3471 SE.getTypeSizeInBits(LU.WidestFixupType) <
3472 SE.getTypeSizeInBits(LF.OperandValToReplace->getType()))
3473 LU.WidestFixupType = LF.OperandValToReplace->getType();
3474 InsertSupplementalFormula(US, LU, LUIdx);
3475 CountRegisters(LU.Formulae.back(), Uses.size() - 1);
3476 break;
3477 }
3478 }
3479 }
3480}
3481
3482/// Split S into subexpressions which can be pulled out into separate
3483/// registers. If C is non-null, multiply each subexpression by C.
3484///
3485/// Return remainder expression after factoring the subexpressions captured by
3486/// Ops. If Ops is complete, return NULL.
3487static const SCEV *CollectSubexprs(const SCEV *S, const SCEVConstant *C,
3488 SmallVectorImpl<const SCEV *> &Ops,
3489 const Loop *L,
3490 ScalarEvolution &SE,
3491 unsigned Depth = 0) {
3492 // Arbitrarily cap recursion to protect compile time.
3493 if (Depth >= 3)
3494 return S;
3495
3496 if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
3497 // Break out add operands.
3498 for (const SCEV *S : Add->operands()) {
3499 const SCEV *Remainder = CollectSubexprs(S, C, Ops, L, SE, Depth+1);
3500 if (Remainder)
3501 Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);
3502 }
3503 return nullptr;
3504 } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
3505 // Split a non-zero base out of an addrec.
3506 if (AR->getStart()->isZero() || !AR->isAffine())
3507 return S;
3508
3509 const SCEV *Remainder = CollectSubexprs(AR->getStart(),
3510 C, Ops, L, SE, Depth+1);
3511 // Split the non-zero AddRec unless it is part of a nested recurrence that
3512 // does not pertain to this loop.
3513 if (Remainder && (AR->getLoop() == L || !isa<SCEVAddRecExpr>(Remainder))) {
3514 Ops.push_back(C ? SE.getMulExpr(C, Remainder) : Remainder);
3515 Remainder = nullptr;
3516 }
3517 if (Remainder != AR->getStart()) {
3518 if (!Remainder)
3519 Remainder = SE.getConstant(AR->getType(), 0);
3520 return SE.getAddRecExpr(Remainder,
3521 AR->getStepRecurrence(SE),
3522 AR->getLoop(),
3523 //FIXME: AR->getNoWrapFlags(SCEV::FlagNW)
3524 SCEV::FlagAnyWrap);
3525 }
3526 } else if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
3527 // Break (C * (a + b + c)) into C*a + C*b + C*c.
3528 if (Mul->getNumOperands() != 2)
3529 return S;
3530 if (const SCEVConstant *Op0 =
3531 dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
3532 C = C ? cast<SCEVConstant>(SE.getMulExpr(C, Op0)) : Op0;
3533 const SCEV *Remainder =
3534 CollectSubexprs(Mul->getOperand(1), C, Ops, L, SE, Depth+1);
3535 if (Remainder)
3536 Ops.push_back(SE.getMulExpr(C, Remainder));
3537 return nullptr;
3538 }
3539 }
3540 return S;
3541}
3542
3543/// Return true if the SCEV represents a value that may end up as a
3544/// post-increment operation.
3545static bool mayUsePostIncMode(const TargetTransformInfo &TTI,
3546 LSRUse &LU, const SCEV *S, const Loop *L,
3547 ScalarEvolution &SE) {
3548 if (LU.Kind != LSRUse::Address ||
3549 !LU.AccessTy.getType()->isIntOrIntVectorTy())
3550 return false;
3551 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S);
3552 if (!AR)
3553 return false;
3554 const SCEV *LoopStep = AR->getStepRecurrence(SE);
3555 if (!isa<SCEVConstant>(LoopStep))
3556 return false;
3557 // Check if a post-indexed load/store can be used.
3558 if (TTI.isIndexedLoadLegal(TTI.MIM_PostInc, AR->getType()) ||
3559 TTI.isIndexedStoreLegal(TTI.MIM_PostInc, AR->getType())) {
3560 const SCEV *LoopStart = AR->getStart();
3561 if (!isa<SCEVConstant>(LoopStart) && SE.isLoopInvariant(LoopStart, L))
3562 return true;
3563 }
3564 return false;
3565}
3566
3567/// Helper function for LSRInstance::GenerateReassociations.
3568void LSRInstance::GenerateReassociationsImpl(LSRUse &LU, unsigned LUIdx,
3569 const Formula &Base,
3570 unsigned Depth, size_t Idx,
3571 bool IsScaledReg) {
3572 const SCEV *BaseReg = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];
3573 // Don't generate reassociations for the base register of a value that
3574 // may generate a post-increment operator. The reason is that the
3575 // reassociations cause extra base+register formula to be created,
3576 // and possibly chosen, but the post-increment is more efficient.
3577 if (TTI.shouldFavorPostInc() && mayUsePostIncMode(TTI, LU, BaseReg, L, SE))
3578 return;
3579 SmallVector<const SCEV *, 8> AddOps;
3580 const SCEV *Remainder = CollectSubexprs(BaseReg, nullptr, AddOps, L, SE);
3581 if (Remainder)
3582 AddOps.push_back(Remainder);
3583
3584 if (AddOps.size() == 1)
3585 return;
3586
3587 for (SmallVectorImpl<const SCEV *>::const_iterator J = AddOps.begin(),
3588 JE = AddOps.end();
3589 J != JE; ++J) {
3590 // Loop-variant "unknown" values are uninteresting; we won't be able to
3591 // do anything meaningful with them.
3592 if (isa<SCEVUnknown>(*J) && !SE.isLoopInvariant(*J, L))
3593 continue;
3594
3595 // Don't pull a constant into a register if the constant could be folded
3596 // into an immediate field.
3597 if (isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind,
3598 LU.AccessTy, *J, Base.getNumRegs() > 1))
3599 continue;
3600
3601 // Collect all operands except *J.
3602 SmallVector<const SCEV *, 8> InnerAddOps(
3603 ((const SmallVector<const SCEV *, 8> &)AddOps).begin(), J);
3604 InnerAddOps.append(std::next(J),
3605 ((const SmallVector<const SCEV *, 8> &)AddOps).end());
3606
3607 // Don't leave just a constant behind in a register if the constant could
3608 // be folded into an immediate field.
3609 if (InnerAddOps.size() == 1 &&
3610 isAlwaysFoldable(TTI, SE, LU.MinOffset, LU.MaxOffset, LU.Kind,
3611 LU.AccessTy, InnerAddOps[0], Base.getNumRegs() > 1))
3612 continue;
3613
3614 const SCEV *InnerSum = SE.getAddExpr(InnerAddOps);
3615 if (InnerSum->isZero())
3616 continue;
3617 Formula F = Base;
3618
3619 // Add the remaining pieces of the add back into the new formula.
3620 const SCEVConstant *InnerSumSC = dyn_cast<SCEVConstant>(InnerSum);
3621 if (InnerSumSC && SE.getTypeSizeInBits(InnerSumSC->getType()) <= 64 &&
3622 TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset +
3623 InnerSumSC->getValue()->getZExtValue())) {
3624 F.UnfoldedOffset =
3625 (uint64_t)F.UnfoldedOffset + InnerSumSC->getValue()->getZExtValue();
3626 if (IsScaledReg)
3627 F.ScaledReg = nullptr;
3628 else
3629 F.BaseRegs.erase(F.BaseRegs.begin() + Idx);
3630 } else if (IsScaledReg)
3631 F.ScaledReg = InnerSum;
3632 else
3633 F.BaseRegs[Idx] = InnerSum;
3634
3635 // Add J as its own register, or an unfolded immediate.
3636 const SCEVConstant *SC = dyn_cast<SCEVConstant>(*J);
3637 if (SC && SE.getTypeSizeInBits(SC->getType()) <= 64 &&
3638 TTI.isLegalAddImmediate((uint64_t)F.UnfoldedOffset +
3639 SC->getValue()->getZExtValue()))
3640 F.UnfoldedOffset =
3641 (uint64_t)F.UnfoldedOffset + SC->getValue()->getZExtValue();
3642 else
3643 F.BaseRegs.push_back(*J);
3644 // We may have changed the number of register in base regs, adjust the
3645 // formula accordingly.
3646 F.canonicalize(*L);
3647
3648 if (InsertFormula(LU, LUIdx, F))
3649 // If that formula hadn't been seen before, recurse to find more like
3650 // it.
3651 // Add check on Log16(AddOps.size()) - same as Log2_32(AddOps.size()) >> 2)
3652 // Because just Depth is not enough to bound compile time.
3653 // This means that every time AddOps.size() is greater 16^x we will add
3654 // x to Depth.
3655 GenerateReassociations(LU, LUIdx, LU.Formulae.back(),
3656 Depth + 1 + (Log2_32(AddOps.size()) >> 2));
3657 }
3658}
3659
3660/// Split out subexpressions from adds and the bases of addrecs.
3661void LSRInstance::GenerateReassociations(LSRUse &LU, unsigned LUIdx,
3662 Formula Base, unsigned Depth) {
3663 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3663, __PRETTY_FUNCTION__))
;
3664 // Arbitrarily cap recursion to protect compile time.
3665 if (Depth >= 3)
3666 return;
3667
3668 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
3669 GenerateReassociationsImpl(LU, LUIdx, Base, Depth, i);
3670
3671 if (Base.Scale == 1)
3672 GenerateReassociationsImpl(LU, LUIdx, Base, Depth,
3673 /* Idx */ -1, /* IsScaledReg */ true);
3674}
3675
3676/// Generate a formula consisting of all of the loop-dominating registers added
3677/// into a single register.
3678void LSRInstance::GenerateCombinations(LSRUse &LU, unsigned LUIdx,
3679 Formula Base) {
3680 // This method is only interesting on a plurality of registers.
3681 if (Base.BaseRegs.size() + (Base.Scale == 1) +
3682 (Base.UnfoldedOffset != 0) <= 1)
3683 return;
3684
3685 // Flatten the representation, i.e., reg1 + 1*reg2 => reg1 + reg2, before
3686 // processing the formula.
3687 Base.unscale();
3688 SmallVector<const SCEV *, 4> Ops;
3689 Formula NewBase = Base;
3690 NewBase.BaseRegs.clear();
3691 Type *CombinedIntegerType = nullptr;
3692 for (const SCEV *BaseReg : Base.BaseRegs) {
3693 if (SE.properlyDominates(BaseReg, L->getHeader()) &&
3694 !SE.hasComputableLoopEvolution(BaseReg, L)) {
3695 if (!CombinedIntegerType)
3696 CombinedIntegerType = SE.getEffectiveSCEVType(BaseReg->getType());
3697 Ops.push_back(BaseReg);
3698 }
3699 else
3700 NewBase.BaseRegs.push_back(BaseReg);
3701 }
3702
3703 // If no register is relevant, we're done.
3704 if (Ops.size() == 0)
3705 return;
3706
3707 // Utility function for generating the required variants of the combined
3708 // registers.
3709 auto GenerateFormula = [&](const SCEV *Sum) {
3710 Formula F = NewBase;
3711
3712 // TODO: If Sum is zero, it probably means ScalarEvolution missed an
3713 // opportunity to fold something. For now, just ignore such cases
3714 // rather than proceed with zero in a register.
3715 if (Sum->isZero())
3716 return;
3717
3718 F.BaseRegs.push_back(Sum);
3719 F.canonicalize(*L);
3720 (void)InsertFormula(LU, LUIdx, F);
3721 };
3722
3723 // If we collected at least two registers, generate a formula combining them.
3724 if (Ops.size() > 1) {
3725 SmallVector<const SCEV *, 4> OpsCopy(Ops); // Don't let SE modify Ops.
3726 GenerateFormula(SE.getAddExpr(OpsCopy));
3727 }
3728
3729 // If we have an unfolded offset, generate a formula combining it with the
3730 // registers collected.
3731 if (NewBase.UnfoldedOffset) {
3732 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3732, __PRETTY_FUNCTION__))
;
3733 Ops.push_back(SE.getConstant(CombinedIntegerType, NewBase.UnfoldedOffset,
3734 true));
3735 NewBase.UnfoldedOffset = 0;
3736 GenerateFormula(SE.getAddExpr(Ops));
3737 }
3738}
3739
3740/// Helper function for LSRInstance::GenerateSymbolicOffsets.
3741void LSRInstance::GenerateSymbolicOffsetsImpl(LSRUse &LU, unsigned LUIdx,
3742 const Formula &Base, size_t Idx,
3743 bool IsScaledReg) {
3744 const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];
3745 GlobalValue *GV = ExtractSymbol(G, SE);
3746 if (G->isZero() || !GV)
3747 return;
3748 Formula F = Base;
3749 F.BaseGV = GV;
3750 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))
3751 return;
3752 if (IsScaledReg)
3753 F.ScaledReg = G;
3754 else
3755 F.BaseRegs[Idx] = G;
3756 (void)InsertFormula(LU, LUIdx, F);
3757}
3758
3759/// Generate reuse formulae using symbolic offsets.
3760void LSRInstance::GenerateSymbolicOffsets(LSRUse &LU, unsigned LUIdx,
3761 Formula Base) {
3762 // We can't add a symbolic offset if the address already contains one.
3763 if (Base.BaseGV) return;
3764
3765 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
3766 GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, i);
3767 if (Base.Scale == 1)
3768 GenerateSymbolicOffsetsImpl(LU, LUIdx, Base, /* Idx */ -1,
3769 /* IsScaledReg */ true);
3770}
3771
3772/// Helper function for LSRInstance::GenerateConstantOffsets.
3773void LSRInstance::GenerateConstantOffsetsImpl(
3774 LSRUse &LU, unsigned LUIdx, const Formula &Base,
3775 const SmallVectorImpl<int64_t> &Worklist, size_t Idx, bool IsScaledReg) {
3776
3777 auto GenerateOffset = [&](const SCEV *G, int64_t Offset) {
3778 Formula F = Base;
3779 F.BaseOffset = (uint64_t)Base.BaseOffset - Offset;
3780
3781 if (isLegalUse(TTI, LU.MinOffset - Offset, LU.MaxOffset - Offset, LU.Kind,
3782 LU.AccessTy, F)) {
3783 // Add the offset to the base register.
3784 const SCEV *NewG = SE.getAddExpr(SE.getConstant(G->getType(), Offset), G);
3785 // If it cancelled out, drop the base register, otherwise update it.
3786 if (NewG->isZero()) {
3787 if (IsScaledReg) {
3788 F.Scale = 0;
3789 F.ScaledReg = nullptr;
3790 } else
3791 F.deleteBaseReg(F.BaseRegs[Idx]);
3792 F.canonicalize(*L);
3793 } else if (IsScaledReg)
3794 F.ScaledReg = NewG;
3795 else
3796 F.BaseRegs[Idx] = NewG;
3797
3798 (void)InsertFormula(LU, LUIdx, F);
3799 }
3800 };
3801
3802 const SCEV *G = IsScaledReg ? Base.ScaledReg : Base.BaseRegs[Idx];
3803
3804 // With constant offsets and constant steps, we can generate pre-inc
3805 // accesses by having the offset equal the step. So, for access #0 with a
3806 // step of 8, we generate a G - 8 base which would require the first access
3807 // to be ((G - 8) + 8),+,8. The pre-indexed access then updates the pointer
3808 // for itself and hopefully becomes the base for other accesses. This means
3809 // means that a single pre-indexed access can be generated to become the new
3810 // base pointer for each iteration of the loop, resulting in no extra add/sub
3811 // instructions for pointer updating.
3812 if (FavorBackedgeIndex && LU.Kind == LSRUse::Address) {
3813 if (auto *GAR = dyn_cast<SCEVAddRecExpr>(G)) {
3814 if (auto *StepRec =
3815 dyn_cast<SCEVConstant>(GAR->getStepRecurrence(SE))) {
3816 const APInt &StepInt = StepRec->getAPInt();
3817 int64_t Step = StepInt.isNegative() ?
3818 StepInt.getSExtValue() : StepInt.getZExtValue();
3819
3820 for (int64_t Offset : Worklist) {
3821 Offset -= Step;
3822 GenerateOffset(G, Offset);
3823 }
3824 }
3825 }
3826 }
3827 for (int64_t Offset : Worklist)
3828 GenerateOffset(G, Offset);
3829
3830 int64_t Imm = ExtractImmediate(G, SE);
3831 if (G->isZero() || Imm == 0)
3832 return;
3833 Formula F = Base;
3834 F.BaseOffset = (uint64_t)F.BaseOffset + Imm;
3835 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))
3836 return;
3837 if (IsScaledReg) {
3838 F.ScaledReg = G;
3839 } else {
3840 F.BaseRegs[Idx] = G;
3841 // We may generate non canonical Formula if G is a recurrent expr reg
3842 // related with current loop while F.ScaledReg is not.
3843 F.canonicalize(*L);
3844 }
3845 (void)InsertFormula(LU, LUIdx, F);
3846}
3847
3848/// GenerateConstantOffsets - Generate reuse formulae using symbolic offsets.
3849void LSRInstance::GenerateConstantOffsets(LSRUse &LU, unsigned LUIdx,
3850 Formula Base) {
3851 // TODO: For now, just add the min and max offset, because it usually isn't
3852 // worthwhile looking at everything inbetween.
3853 SmallVector<int64_t, 2> Worklist;
3854 Worklist.push_back(LU.MinOffset);
3855 if (LU.MaxOffset != LU.MinOffset)
3856 Worklist.push_back(LU.MaxOffset);
3857
3858 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
3859 GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, i);
3860 if (Base.Scale == 1)
3861 GenerateConstantOffsetsImpl(LU, LUIdx, Base, Worklist, /* Idx */ -1,
3862 /* IsScaledReg */ true);
3863}
3864
3865/// For ICmpZero, check to see if we can scale up the comparison. For example, x
3866/// == y -> x*c == y*c.
3867void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx,
3868 Formula Base) {
3869 if (LU.Kind != LSRUse::ICmpZero) return;
3870
3871 // Determine the integer type for the base formula.
3872 Type *IntTy = Base.getType();
3873 if (!IntTy) return;
3874 if (SE.getTypeSizeInBits(IntTy) > 64) return;
3875
3876 // Don't do this if there is more than one offset.
3877 if (LU.MinOffset != LU.MaxOffset) return;
3878
3879 // Check if transformation is valid. It is illegal to multiply pointer.
3880 if (Base.ScaledReg && Base.ScaledReg->getType()->isPointerTy())
3881 return;
3882 for (const SCEV *BaseReg : Base.BaseRegs)
3883 if (BaseReg->getType()->isPointerTy())
3884 return;
3885 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3885, __PRETTY_FUNCTION__))
;
3886
3887 // Check each interesting stride.
3888 for (int64_t Factor : Factors) {
3889 // Check that the multiplication doesn't overflow.
3890 if (Base.BaseOffset == std::numeric_limits<int64_t>::min() && Factor == -1)
3891 continue;
3892 int64_t NewBaseOffset = (uint64_t)Base.BaseOffset * Factor;
3893 if (NewBaseOffset / Factor != Base.BaseOffset)
3894 continue;
3895 // If the offset will be truncated at this use, check that it is in bounds.
3896 if (!IntTy->isPointerTy() &&
3897 !ConstantInt::isValueValidForType(IntTy, NewBaseOffset))
3898 continue;
3899
3900 // Check that multiplying with the use offset doesn't overflow.
3901 int64_t Offset = LU.MinOffset;
3902 if (Offset == std::numeric_limits<int64_t>::min() && Factor == -1)
3903 continue;
3904 Offset = (uint64_t)Offset * Factor;
3905 if (Offset / Factor != LU.MinOffset)
3906 continue;
3907 // If the offset will be truncated at this use, check that it is in bounds.
3908 if (!IntTy->isPointerTy() &&
3909 !ConstantInt::isValueValidForType(IntTy, Offset))
3910 continue;
3911
3912 Formula F = Base;
3913 F.BaseOffset = NewBaseOffset;
3914
3915 // Check that this scale is legal.
3916 if (!isLegalUse(TTI, Offset, Offset, LU.Kind, LU.AccessTy, F))
3917 continue;
3918
3919 // Compensate for the use having MinOffset built into it.
3920 F.BaseOffset = (uint64_t)F.BaseOffset + Offset - LU.MinOffset;
3921
3922 const SCEV *FactorS = SE.getConstant(IntTy, Factor);
3923
3924 // Check that multiplying with each base register doesn't overflow.
3925 for (size_t i = 0, e = F.BaseRegs.size(); i != e; ++i) {
3926 F.BaseRegs[i] = SE.getMulExpr(F.BaseRegs[i], FactorS);
3927 if (getExactSDiv(F.BaseRegs[i], FactorS, SE) != Base.BaseRegs[i])
3928 goto next;
3929 }
3930
3931 // Check that multiplying with the scaled register doesn't overflow.
3932 if (F.ScaledReg) {
3933 F.ScaledReg = SE.getMulExpr(F.ScaledReg, FactorS);
3934 if (getExactSDiv(F.ScaledReg, FactorS, SE) != Base.ScaledReg)
3935 continue;
3936 }
3937
3938 // Check that multiplying with the unfolded offset doesn't overflow.
3939 if (F.UnfoldedOffset != 0) {
3940 if (F.UnfoldedOffset == std::numeric_limits<int64_t>::min() &&
3941 Factor == -1)
3942 continue;
3943 F.UnfoldedOffset = (uint64_t)F.UnfoldedOffset * Factor;
3944 if (F.UnfoldedOffset / Factor != Base.UnfoldedOffset)
3945 continue;
3946 // If the offset will be truncated, check that it is in bounds.
3947 if (!IntTy->isPointerTy() &&
3948 !ConstantInt::isValueValidForType(IntTy, F.UnfoldedOffset))
3949 continue;
3950 }
3951
3952 // If we make it here and it's legal, add it.
3953 (void)InsertFormula(LU, LUIdx, F);
3954 next:;
3955 }
3956}
3957
3958/// Generate stride factor reuse formulae by making use of scaled-offset address
3959/// modes, for example.
3960void LSRInstance::GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base) {
3961 // Determine the integer type for the base formula.
3962 Type *IntTy = Base.getType();
3963 if (!IntTy) return;
3964
3965 // If this Formula already has a scaled register, we can't add another one.
3966 // Try to unscale the formula to generate a better scale.
3967 if (Base.Scale != 0 && !Base.unscale())
3968 return;
3969
3970 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 3970, __PRETTY_FUNCTION__))
;
3971
3972 // Check each interesting stride.
3973 for (int64_t Factor : Factors) {
3974 Base.Scale = Factor;
3975 Base.HasBaseReg = Base.BaseRegs.size() > 1;
3976 // Check whether this scale is going to be legal.
3977 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,
3978 Base)) {
3979 // As a special-case, handle special out-of-loop Basic users specially.
3980 // TODO: Reconsider this special case.
3981 if (LU.Kind == LSRUse::Basic &&
3982 isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LSRUse::Special,
3983 LU.AccessTy, Base) &&
3984 LU.AllFixupsOutsideLoop)
3985 LU.Kind = LSRUse::Special;
3986 else
3987 continue;
3988 }
3989 // For an ICmpZero, negating a solitary base register won't lead to
3990 // new solutions.
3991 if (LU.Kind == LSRUse::ICmpZero &&
3992 !Base.HasBaseReg && Base.BaseOffset == 0 && !Base.BaseGV)
3993 continue;
3994 // For each addrec base reg, if its loop is current loop, apply the scale.
3995 for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) {
3996 const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Base.BaseRegs[i]);
3997 if (AR && (AR->getLoop() == L || LU.AllFixupsOutsideLoop)) {
3998 const SCEV *FactorS = SE.getConstant(IntTy, Factor);
3999 if (FactorS->isZero())
4000 continue;
4001 // Divide out the factor, ignoring high bits, since we'll be
4002 // scaling the value back up in the end.
4003 if (const SCEV *Quotient = getExactSDiv(AR, FactorS, SE, true)) {
4004 // TODO: This could be optimized to avoid all the copying.
4005 Formula F = Base;
4006 F.ScaledReg = Quotient;
4007 F.deleteBaseReg(F.BaseRegs[i]);
4008 // The canonical representation of 1*reg is reg, which is already in
4009 // Base. In that case, do not try to insert the formula, it will be
4010 // rejected anyway.
4011 if (F.Scale == 1 && (F.BaseRegs.empty() ||
4012 (AR->getLoop() != L && LU.AllFixupsOutsideLoop)))
4013 continue;
4014 // If AllFixupsOutsideLoop is true and F.Scale is 1, we may generate
4015 // non canonical Formula with ScaledReg's loop not being L.
4016 if (F.Scale == 1 && LU.AllFixupsOutsideLoop)
4017 F.canonicalize(*L);
4018 (void)InsertFormula(LU, LUIdx, F);
4019 }
4020 }
4021 }
4022 }
4023}
4024
4025/// Generate reuse formulae from different IV types.
4026void LSRInstance::GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base) {
4027 // Don't bother truncating symbolic values.
4028 if (Base.BaseGV) return;
4029
4030 // Determine the integer type for the base formula.
4031 Type *DstTy = Base.getType();
4032 if (!DstTy) return;
4033 DstTy = SE.getEffectiveSCEVType(DstTy);
4034
4035 for (Type *SrcTy : Types) {
4036 if (SrcTy != DstTy && TTI.isTruncateFree(SrcTy, DstTy)) {
4037 Formula F = Base;
4038
4039 // Sometimes SCEV is able to prove zero during ext transform. It may
4040 // happen if SCEV did not do all possible transforms while creating the
4041 // initial node (maybe due to depth limitations), but it can do them while
4042 // taking ext.
4043 if (F.ScaledReg) {
4044 const SCEV *NewScaledReg = SE.getAnyExtendExpr(F.ScaledReg, SrcTy);
4045 if (NewScaledReg->isZero())
4046 continue;
4047 F.ScaledReg = NewScaledReg;
4048 }
4049 bool HasZeroBaseReg = false;
4050 for (const SCEV *&BaseReg : F.BaseRegs) {
4051 const SCEV *NewBaseReg = SE.getAnyExtendExpr(BaseReg, SrcTy);
4052 if (NewBaseReg->isZero()) {
4053 HasZeroBaseReg = true;
4054 break;
4055 }
4056 BaseReg = NewBaseReg;
4057 }
4058 if (HasZeroBaseReg)
4059 continue;
4060
4061 // TODO: This assumes we've done basic processing on all uses and
4062 // have an idea what the register usage is.
4063 if (!F.hasRegsUsedByUsesOtherThan(LUIdx, RegUses))
4064 continue;
4065
4066 F.canonicalize(*L);
4067 (void)InsertFormula(LU, LUIdx, F);
4068 }
4069 }
4070}
4071
4072namespace {
4073
4074/// Helper class for GenerateCrossUseConstantOffsets. It's used to defer
4075/// modifications so that the search phase doesn't have to worry about the data
4076/// structures moving underneath it.
4077struct WorkItem {
4078 size_t LUIdx;
4079 int64_t Imm;
4080 const SCEV *OrigReg;
4081
4082 WorkItem(size_t LI, int64_t I, const SCEV *R)
4083 : LUIdx(LI), Imm(I), OrigReg(R) {}
4084
4085 void print(raw_ostream &OS) const;
4086 void dump() const;
4087};
4088
4089} // end anonymous namespace
4090
4091#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
4092void WorkItem::print(raw_ostream &OS) const {
4093 OS << "in formulae referencing " << *OrigReg << " in use " << LUIdx
4094 << " , add offset " << Imm;
4095}
4096
4097LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void WorkItem::dump() const {
4098 print(errs()); errs() << '\n';
4099}
4100#endif
4101
4102/// Look for registers which are a constant distance apart and try to form reuse
4103/// opportunities between them.
4104void LSRInstance::GenerateCrossUseConstantOffsets() {
4105 // Group the registers by their value without any added constant offset.
4106 using ImmMapTy = std::map<int64_t, const SCEV *>;
4107
4108 DenseMap<const SCEV *, ImmMapTy> Map;
4109 DenseMap<const SCEV *, SmallBitVector> UsedByIndicesMap;
4110 SmallVector<const SCEV *, 8> Sequence;
4111 for (const SCEV *Use : RegUses) {
4112 const SCEV *Reg = Use; // Make a copy for ExtractImmediate to modify.
4113 int64_t Imm = ExtractImmediate(Reg, SE);
4114 auto Pair = Map.insert(std::make_pair(Reg, ImmMapTy()));
4115 if (Pair.second)
4116 Sequence.push_back(Reg);
4117 Pair.first->second.insert(std::make_pair(Imm, Use));
4118 UsedByIndicesMap[Reg] |= RegUses.getUsedByIndices(Use);
4119 }
4120
4121 // Now examine each set of registers with the same base value. Build up
4122 // a list of work to do and do the work in a separate step so that we're
4123 // not adding formulae and register counts while we're searching.
4124 SmallVector<WorkItem, 32> WorkItems;
4125 SmallSet<std::pair<size_t, int64_t>, 32> UniqueItems;
4126 for (const SCEV *Reg : Sequence) {
4127 const ImmMapTy &Imms = Map.find(Reg)->second;
4128
4129 // It's not worthwhile looking for reuse if there's only one offset.
4130 if (Imms.size() == 1)
4131 continue;
4132
4133 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)
4134 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)
4135 : 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)
4136 << ' ' << 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)
4137 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)
;
4138
4139 // Examine each offset.
4140 for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end();
4141 J != JE; ++J) {
4142 const SCEV *OrigReg = J->second;
4143
4144 int64_t JImm = J->first;
4145 const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(OrigReg);
4146
4147 if (!isa<SCEVConstant>(OrigReg) &&
4148 UsedByIndicesMap[Reg].count() == 1) {
4149 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)
4150 << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Skipping cross-use reuse for "
<< *OrigReg << '\n'; } } while (false)
;
4151 continue;
4152 }
4153
4154 // Conservatively examine offsets between this orig reg a few selected
4155 // other orig regs.
4156 int64_t First = Imms.begin()->first;
4157 int64_t Last = std::prev(Imms.end())->first;
4158 // Compute (First + Last) / 2 without overflow using the fact that
4159 // First + Last = 2 * (First + Last) + (First ^ Last).
4160 int64_t Avg = (First & Last) + ((First ^ Last) >> 1);
4161 // If the result is negative and First is odd and Last even (or vice versa),
4162 // we rounded towards -inf. Add 1 in that case, to round towards 0.
4163 Avg = Avg + ((First ^ Last) & ((uint64_t)Avg >> 63));
4164 ImmMapTy::const_iterator OtherImms[] = {
4165 Imms.begin(), std::prev(Imms.end()),
4166 Imms.lower_bound(Avg)};
4167 for (size_t i = 0, e = array_lengthof(OtherImms); i != e; ++i) {
4168 ImmMapTy::const_iterator M = OtherImms[i];
4169 if (M == J || M == JE) continue;
4170
4171 // Compute the difference between the two.
4172 int64_t Imm = (uint64_t)JImm - M->first;
4173 for (unsigned LUIdx : UsedByIndices.set_bits())
4174 // Make a memo of this use, offset, and register tuple.
4175 if (UniqueItems.insert(std::make_pair(LUIdx, Imm)).second)
4176 WorkItems.push_back(WorkItem(LUIdx, Imm, OrigReg));
4177 }
4178 }
4179 }
4180
4181 Map.clear();
4182 Sequence.clear();
4183 UsedByIndicesMap.clear();
4184 UniqueItems.clear();
4185
4186 // Now iterate through the worklist and add new formulae.
4187 for (const WorkItem &WI : WorkItems) {
4188 size_t LUIdx = WI.LUIdx;
4189 LSRUse &LU = Uses[LUIdx];
4190 int64_t Imm = WI.Imm;
4191 const SCEV *OrigReg = WI.OrigReg;
4192
4193 Type *IntTy = SE.getEffectiveSCEVType(OrigReg->getType());
4194 const SCEV *NegImmS = SE.getSCEV(ConstantInt::get(IntTy, -(uint64_t)Imm));
4195 unsigned BitWidth = SE.getTypeSizeInBits(IntTy);
4196
4197 // TODO: Use a more targeted data structure.
4198 for (size_t L = 0, LE = LU.Formulae.size(); L != LE; ++L) {
4199 Formula F = LU.Formulae[L];
4200 // FIXME: The code for the scaled and unscaled registers looks
4201 // very similar but slightly different. Investigate if they
4202 // could be merged. That way, we would not have to unscale the
4203 // Formula.
4204 F.unscale();
4205 // Use the immediate in the scaled register.
4206 if (F.ScaledReg == OrigReg) {
4207 int64_t Offset = (uint64_t)F.BaseOffset + Imm * (uint64_t)F.Scale;
4208 // Don't create 50 + reg(-50).
4209 if (F.referencesReg(SE.getSCEV(
4210 ConstantInt::get(IntTy, -(uint64_t)Offset))))
4211 continue;
4212 Formula NewF = F;
4213 NewF.BaseOffset = Offset;
4214 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy,
4215 NewF))
4216 continue;
4217 NewF.ScaledReg = SE.getAddExpr(NegImmS, NewF.ScaledReg);
4218
4219 // If the new scale is a constant in a register, and adding the constant
4220 // value to the immediate would produce a value closer to zero than the
4221 // immediate itself, then the formula isn't worthwhile.
4222 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewF.ScaledReg))
4223 if (C->getValue()->isNegative() != (NewF.BaseOffset < 0) &&
4224 (C->getAPInt().abs() * APInt(BitWidth, F.Scale))
4225 .ule(std::abs(NewF.BaseOffset)))
4226 continue;
4227
4228 // OK, looks good.
4229 NewF.canonicalize(*this->L);
4230 (void)InsertFormula(LU, LUIdx, NewF);
4231 } else {
4232 // Use the immediate in a base register.
4233 for (size_t N = 0, NE = F.BaseRegs.size(); N != NE; ++N) {
4234 const SCEV *BaseReg = F.BaseRegs[N];
4235 if (BaseReg != OrigReg)
4236 continue;
4237 Formula NewF = F;
4238 NewF.BaseOffset = (uint64_t)NewF.BaseOffset + Imm;
4239 if (!isLegalUse(TTI, LU.MinOffset, LU.MaxOffset,
4240 LU.Kind, LU.AccessTy, NewF)) {
4241 if (TTI.shouldFavorPostInc() &&
4242 mayUsePostIncMode(TTI, LU, OrigReg, this->L, SE))
4243 continue;
4244 if (!TTI.isLegalAddImmediate((uint64_t)NewF.UnfoldedOffset + Imm))
4245 continue;
4246 NewF = F;
4247 NewF.UnfoldedOffset = (uint64_t)NewF.UnfoldedOffset + Imm;
4248 }
4249 NewF.BaseRegs[N] = SE.getAddExpr(NegImmS, BaseReg);
4250
4251 // If the new formula has a constant in a register, and adding the
4252 // constant value to the immediate would produce a value closer to
4253 // zero than the immediate itself, then the formula isn't worthwhile.
4254 for (const SCEV *NewReg : NewF.BaseRegs)
4255 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(NewReg))
4256 if ((C->getAPInt() + NewF.BaseOffset)
4257 .abs()
4258 .slt(std::abs(NewF.BaseOffset)) &&
4259 (C->getAPInt() + NewF.BaseOffset).countTrailingZeros() >=
4260 countTrailingZeros<uint64_t>(NewF.BaseOffset))
4261 goto skip_formula;
4262
4263 // Ok, looks good.
4264 NewF.canonicalize(*this->L);
4265 (void)InsertFormula(LU, LUIdx, NewF);
4266 break;
4267 skip_formula:;
4268 }
4269 }
4270 }
4271 }
4272}
4273
4274/// Generate formulae for each use.
4275void
4276LSRInstance::GenerateAllReuseFormulae() {
4277 // This is split into multiple loops so that hasRegsUsedByUsesOtherThan
4278 // queries are more precise.
4279 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4280 LSRUse &LU = Uses[LUIdx];
4281 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4282 GenerateReassociations(LU, LUIdx, LU.Formulae[i]);
4283 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4284 GenerateCombinations(LU, LUIdx, LU.Formulae[i]);
4285 }
4286 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4287 LSRUse &LU = Uses[LUIdx];
4288 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4289 GenerateSymbolicOffsets(LU, LUIdx, LU.Formulae[i]);
4290 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4291 GenerateConstantOffsets(LU, LUIdx, LU.Formulae[i]);
4292 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4293 GenerateICmpZeroScales(LU, LUIdx, LU.Formulae[i]);
4294 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4295 GenerateScales(LU, LUIdx, LU.Formulae[i]);
4296 }
4297 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4298 LSRUse &LU = Uses[LUIdx];
4299 for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
4300 GenerateTruncates(LU, LUIdx, LU.Formulae[i]);
4301 }
4302
4303 GenerateCrossUseConstantOffsets();
4304
4305 LLVM_DEBUG(dbgs() << "\n"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (false)
4306 "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)
4307 print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\n" "After generating reuse formulae:\n"
; print_uses(dbgs()); } } while (false)
;
4308}
4309
4310/// If there are multiple formulae with the same set of registers used
4311/// by other uses, pick the best one and delete the others.
4312void LSRInstance::FilterOutUndesirableDedicatedRegisters() {
4313 DenseSet<const SCEV *> VisitedRegs;
4314 SmallPtrSet<const SCEV *, 16> Regs;
4315 SmallPtrSet<const SCEV *, 16> LoserRegs;
4316#ifndef NDEBUG
4317 bool ChangedFormulae = false;
4318#endif
4319
4320 // Collect the best formula for each unique set of shared registers. This
4321 // is reset for each use.
4322 using BestFormulaeTy =
4323 DenseMap<SmallVector<const SCEV *, 4>, size_t, UniquifierDenseMapInfo>;
4324
4325 BestFormulaeTy BestFormulae;
4326
4327 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4328 LSRUse &LU = Uses[LUIdx];
4329 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)
4330 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Filtering for use "; LU.print
(dbgs()); dbgs() << '\n'; } } while (false)
;
4331
4332 bool Any = false;
4333 for (size_t FIdx = 0, NumForms = LU.Formulae.size();
4334 FIdx != NumForms; ++FIdx) {
4335 Formula &F = LU.Formulae[FIdx];
4336
4337 // Some formulas are instant losers. For example, they may depend on
4338 // nonexistent AddRecs from other loops. These need to be filtered
4339 // immediately, otherwise heuristics could choose them over others leading
4340 // to an unsatisfactory solution. Passing LoserRegs into RateFormula here
4341 // avoids the need to recompute this information across formulae using the
4342 // same bad AddRec. Passing LoserRegs is also essential unless we remove
4343 // the corresponding bad register from the Regs set.
4344 Cost CostF(L, SE, TTI);
4345 Regs.clear();
4346 CostF.RateFormula(F, Regs, VisitedRegs, LU, &LoserRegs);
4347 if (CostF.isLoser()) {
4348 // During initial formula generation, undesirable formulae are generated
4349 // by uses within other loops that have some non-trivial address mode or
4350 // use the postinc form of the IV. LSR needs to provide these formulae
4351 // as the basis of rediscovering the desired formula that uses an AddRec
4352 // corresponding to the existing phi. Once all formulae have been
4353 // generated, these initial losers may be pruned.
4354 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)
4355 dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering loser "; F.print
(dbgs()); dbgs() << "\n"; } } while (false)
;
4356 }
4357 else {
4358 SmallVector<const SCEV *, 4> Key;
4359 for (const SCEV *Reg : F.BaseRegs) {
4360 if (RegUses.isRegUsedByUsesOtherThan(Reg, LUIdx))
4361 Key.push_back(Reg);
4362 }
4363 if (F.ScaledReg &&
4364 RegUses.isRegUsedByUsesOtherThan(F.ScaledReg, LUIdx))
4365 Key.push_back(F.ScaledReg);
4366 // Unstable sort by host order ok, because this is only used for
4367 // uniquifying.
4368 llvm::sort(Key);
4369
4370 std::pair<BestFormulaeTy::const_iterator, bool> P =
4371 BestFormulae.insert(std::make_pair(Key, FIdx));
4372 if (P.second)
4373 continue;
4374
4375 Formula &Best = LU.Formulae[P.first->second];
4376
4377 Cost CostBest(L, SE, TTI);
4378 Regs.clear();
4379 CostBest.RateFormula(Best, Regs, VisitedRegs, LU);
4380 if (CostF.isLess(CostBest))
4381 std::swap(F, Best);
4382 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)
4383 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)
4384 " 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)
4385 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)
;
4386 }
4387#ifndef NDEBUG
4388 ChangedFormulae = true;
4389#endif
4390 LU.DeleteFormula(F);
4391 --FIdx;
4392 --NumForms;
4393 Any = true;
4394 }
4395
4396 // Now that we've filtered out some formulae, recompute the Regs set.
4397 if (Any)
4398 LU.RecomputeRegs(LUIdx, RegUses);
4399
4400 // Reset this to prepare for the next use.
4401 BestFormulae.clear();
4402 }
4403
4404 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)
4405 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)
4406 "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)
4407 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)
4408 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
;
4409}
4410
4411/// Estimate the worst-case number of solutions the solver might have to
4412/// consider. It almost never considers this many solutions because it prune the
4413/// search space, but the pruning isn't always sufficient.
4414size_t LSRInstance::EstimateSearchSpaceComplexity() const {
4415 size_t Power = 1;
4416 for (const LSRUse &LU : Uses) {
4417 size_t FSize = LU.Formulae.size();
4418 if (FSize >= ComplexityLimit) {
4419 Power = ComplexityLimit;
4420 break;
4421 }
4422 Power *= FSize;
4423 if (Power >= ComplexityLimit)
4424 break;
4425 }
4426 return Power;
4427}
4428
4429/// When one formula uses a superset of the registers of another formula, it
4430/// won't help reduce register pressure (though it may not necessarily hurt
4431/// register pressure); remove it to simplify the system.
4432void LSRInstance::NarrowSearchSpaceByDetectingSupersets() {
4433 if (EstimateSearchSpaceComplexity() >= ComplexityLimit) {
4434 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)
;
4435
4436 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)
4437 "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)
4438 "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)
;
4439
4440 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4441 LSRUse &LU = Uses[LUIdx];
4442 bool Any = false;
4443 for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {
4444 Formula &F = LU.Formulae[i];
4445 // Look for a formula with a constant or GV in a register. If the use
4446 // also has a formula with that same value in an immediate field,
4447 // delete the one that uses a register.
4448 for (SmallVectorImpl<const SCEV *>::const_iterator
4449 I = F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I) {
4450 if (const SCEVConstant *C = dyn_cast<SCEVConstant>(*I)) {
4451 Formula NewF = F;
4452 //FIXME: Formulas should store bitwidth to do wrapping properly.
4453 // See PR41034.
4454 NewF.BaseOffset += (uint64_t)C->getValue()->getSExtValue();
4455 NewF.BaseRegs.erase(NewF.BaseRegs.begin() +
4456 (I - F.BaseRegs.begin()));
4457 if (LU.HasFormulaWithSameRegs(NewF)) {
4458 LLVM_DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (false)
4459 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (false)
;
4460 LU.DeleteFormula(F);
4461 --i;
4462 --e;
4463 Any = true;
4464 break;
4465 }
4466 } else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(*I)) {
4467 if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue()))
4468 if (!F.BaseGV) {
4469 Formula NewF = F;
4470 NewF.BaseGV = GV;
4471 NewF.BaseRegs.erase(NewF.BaseRegs.begin() +
4472 (I - F.BaseRegs.begin()));
4473 if (LU.HasFormulaWithSameRegs(NewF)) {
4474 LLVM_DEBUG(dbgs() << " Deleting "; F.print(dbgs());do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (false)
4475 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; F.print(dbgs
()); dbgs() << '\n'; } } while (false)
;
4476 LU.DeleteFormula(F);
4477 --i;
4478 --e;
4479 Any = true;
4480 break;
4481 }
4482 }
4483 }
4484 }
4485 }
4486 if (Any)
4487 LU.RecomputeRegs(LUIdx, RegUses);
4488 }
4489
4490 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)
;
4491 }
4492}
4493
4494/// When there are many registers for expressions like A, A+1, A+2, etc.,
4495/// allocate a single register for them.
4496void LSRInstance::NarrowSearchSpaceByCollapsingUnrolledCode() {
4497 if (EstimateSearchSpaceComplexity() < ComplexityLimit)
4498 return;
4499
4500 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)
4501 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)
4502 "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)
4503 "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)
;
4504
4505 // This is especially useful for unrolled loops.
4506
4507 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4508 LSRUse &LU = Uses[LUIdx];
4509 for (const Formula &F : LU.Formulae) {
4510 if (F.BaseOffset == 0 || (F.Scale != 0 && F.Scale != 1))
4511 continue;
4512
4513 LSRUse *LUThatHas = FindUseWithSimilarFormula(F, LU);
4514 if (!LUThatHas)
4515 continue;
4516
4517 if (!reconcileNewOffset(*LUThatHas, F.BaseOffset, /*HasBaseReg=*/ false,
4518 LU.Kind, LU.AccessTy))
4519 continue;
4520
4521 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)
;
4522
4523 LUThatHas->AllFixupsOutsideLoop &= LU.AllFixupsOutsideLoop;
4524
4525 // Transfer the fixups of LU to LUThatHas.
4526 for (LSRFixup &Fixup : LU.Fixups) {
4527 Fixup.Offset += F.BaseOffset;
4528 LUThatHas->pushFixup(Fixup);
4529 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)
;
4530 }
4531
4532 // Delete formulae from the new use which are no longer legal.
4533 bool Any = false;
4534 for (size_t i = 0, e = LUThatHas->Formulae.size(); i != e; ++i) {
4535 Formula &F = LUThatHas->Formulae[i];
4536 if (!isLegalUse(TTI, LUThatHas->MinOffset, LUThatHas->MaxOffset,
4537 LUThatHas->Kind, LUThatHas->AccessTy, F)) {
4538 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)
;
4539 LUThatHas->DeleteFormula(F);
4540 --i;
4541 --e;
4542 Any = true;
4543 }
4544 }
4545
4546 if (Any)
4547 LUThatHas->RecomputeRegs(LUThatHas - &Uses.front(), RegUses);
4548
4549 // Delete the old use.
4550 DeleteUse(LU, LUIdx);
4551 --LUIdx;
4552 --NumUses;
4553 break;
4554 }
4555 }
4556
4557 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)
;
4558}
4559
4560/// Call FilterOutUndesirableDedicatedRegisters again, if necessary, now that
4561/// we've done more filtering, as it may be able to find more formulae to
4562/// eliminate.
4563void LSRInstance::NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters(){
4564 if (EstimateSearchSpaceComplexity() >= ComplexityLimit) {
4565 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)
;
4566
4567 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)
4568 "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)
;
4569
4570 FilterOutUndesirableDedicatedRegisters();
4571
4572 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)
;
4573 }
4574}
4575
4576/// If a LSRUse has multiple formulae with the same ScaledReg and Scale.
4577/// Pick the best one and delete the others.
4578/// This narrowing heuristic is to keep as many formulae with different
4579/// Scale and ScaledReg pair as possible while narrowing the search space.
4580/// The benefit is that it is more likely to find out a better solution
4581/// from a formulae set with more Scale and ScaledReg variations than
4582/// a formulae set with the same Scale and ScaledReg. The picking winner
4583/// reg heuristic will often keep the formulae with the same Scale and
4584/// ScaledReg and filter others, and we want to avoid that if possible.
4585void LSRInstance::NarrowSearchSpaceByFilterFormulaWithSameScaledReg() {
4586 if (EstimateSearchSpaceComplexity() < ComplexityLimit)
4587 return;
4588
4589 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)
4590 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)
4591 "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)
4592 "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)
;
4593
4594 // Map the "Scale * ScaledReg" pair to the best formula of current LSRUse.
4595 using BestFormulaeTy = DenseMap<std::pair<const SCEV *, int64_t>, size_t>;
4596
4597 BestFormulaeTy BestFormulae;
4598#ifndef NDEBUG
4599 bool ChangedFormulae = false;
4600#endif
4601 DenseSet<const SCEV *> VisitedRegs;
4602 SmallPtrSet<const SCEV *, 16> Regs;
4603
4604 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4605 LSRUse &LU = Uses[LUIdx];
4606 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)
4607 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Filtering for use "; LU.print
(dbgs()); dbgs() << '\n'; } } while (false)
;
4608
4609 // Return true if Formula FA is better than Formula FB.
4610 auto IsBetterThan = [&](Formula &FA, Formula &FB) {
4611 // First we will try to choose the Formula with fewer new registers.
4612 // For a register used by current Formula, the more the register is
4613 // shared among LSRUses, the less we increase the register number
4614 // counter of the formula.
4615 size_t FARegNum = 0;
4616 for (const SCEV *Reg : FA.BaseRegs) {
4617 const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(Reg);
4618 FARegNum += (NumUses - UsedByIndices.count() + 1);
4619 }
4620 size_t FBRegNum = 0;
4621 for (const SCEV *Reg : FB.BaseRegs) {
4622 const SmallBitVector &UsedByIndices = RegUses.getUsedByIndices(Reg);
4623 FBRegNum += (NumUses - UsedByIndices.count() + 1);
4624 }
4625 if (FARegNum != FBRegNum)
4626 return FARegNum < FBRegNum;
4627
4628 // If the new register numbers are the same, choose the Formula with
4629 // less Cost.
4630 Cost CostFA(L, SE, TTI);
4631 Cost CostFB(L, SE, TTI);
4632 Regs.clear();
4633 CostFA.RateFormula(FA, Regs, VisitedRegs, LU);
4634 Regs.clear();
4635 CostFB.RateFormula(FB, Regs, VisitedRegs, LU);
4636 return CostFA.isLess(CostFB);
4637 };
4638
4639 bool Any = false;
4640 for (size_t FIdx = 0, NumForms = LU.Formulae.size(); FIdx != NumForms;
4641 ++FIdx) {
4642 Formula &F = LU.Formulae[FIdx];
4643 if (!F.ScaledReg)
4644 continue;
4645 auto P = BestFormulae.insert({{F.ScaledReg, F.Scale}, FIdx});
4646 if (P.second)
4647 continue;
4648
4649 Formula &Best = LU.Formulae[P.first->second];
4650 if (IsBetterThan(F, Best))
4651 std::swap(F, Best);
4652 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)
4653 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)
4654 " 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)
4655 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)
;
4656#ifndef NDEBUG
4657 ChangedFormulae = true;
4658#endif
4659 LU.DeleteFormula(F);
4660 --FIdx;
4661 --NumForms;
4662 Any = true;
4663 }
4664 if (Any)
4665 LU.RecomputeRegs(LUIdx, RegUses);
4666
4667 // Reset this to prepare for the next use.
4668 BestFormulae.clear();
4669 }
4670
4671 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)
4672 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)
4673 "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)
4674 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)
4675 })do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { if (ChangedFormulae) { dbgs() << "\n"
"After filtering out undesirable candidates:\n"; print_uses(
dbgs()); }; } } while (false)
;
4676}
4677
4678/// If we are over the complexity limit, filter out any post-inc prefering
4679/// variables to only post-inc values.
4680void LSRInstance::NarrowSearchSpaceByFilterPostInc() {
4681 if (!TTI.shouldFavorPostInc())
4682 return;
4683 if (EstimateSearchSpaceComplexity() < ComplexityLimit)
4684 return;
4685
4686 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"
"Narrowing the search space by choosing the lowest " "register Formula for PostInc Uses.\n"
; } } while (false)
4687 "Narrowing the search space by choosing the lowest "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by choosing the lowest " "register Formula for PostInc Uses.\n"
; } } while (false)
4688 "register Formula for PostInc Uses.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "The search space is too complex.\n"
"Narrowing the search space by choosing the lowest " "register Formula for PostInc Uses.\n"
; } } while (false)
;
4689
4690 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4691 LSRUse &LU = Uses[LUIdx];
4692
4693 if (LU.Kind != LSRUse::Address)
4694 continue;
4695 if (!TTI.isIndexedLoadLegal(TTI.MIM_PostInc, LU.AccessTy.getType()) &&
4696 !TTI.isIndexedStoreLegal(TTI.MIM_PostInc, LU.AccessTy.getType()))
4697 continue;
4698
4699 size_t MinRegs = std::numeric_limits<size_t>::max();
4700 for (const Formula &F : LU.Formulae)
4701 MinRegs = std::min(F.getNumRegs(), MinRegs);
4702
4703 bool Any = false;
4704 for (size_t FIdx = 0, NumForms = LU.Formulae.size(); FIdx != NumForms;
4705 ++FIdx) {
4706 Formula &F = LU.Formulae[FIdx];
4707 if (F.getNumRegs() > MinRegs) {
4708 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"; } } while (false)
4709 dbgs() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Filtering out formula "
; F.print(dbgs()); dbgs() << "\n"; } } while (false)
;
4710 LU.DeleteFormula(F);
4711 --FIdx;
4712 --NumForms;
4713 Any = true;
4714 }
4715 }
4716 if (Any)
4717 LU.RecomputeRegs(LUIdx, RegUses);
4718
4719 if (EstimateSearchSpaceComplexity() < ComplexityLimit)
4720 break;
4721 }
4722
4723 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)
;
4724}
4725
4726/// The function delete formulas with high registers number expectation.
4727/// Assuming we don't know the value of each formula (already delete
4728/// all inefficient), generate probability of not selecting for each
4729/// register.
4730/// For example,
4731/// Use1:
4732/// reg(a) + reg({0,+,1})
4733/// reg(a) + reg({-1,+,1}) + 1
4734/// reg({a,+,1})
4735/// Use2:
4736/// reg(b) + reg({0,+,1})
4737/// reg(b) + reg({-1,+,1}) + 1
4738/// reg({b,+,1})
4739/// Use3:
4740/// reg(c) + reg(b) + reg({0,+,1})
4741/// reg(c) + reg({b,+,1})
4742///
4743/// Probability of not selecting
4744/// Use1 Use2 Use3
4745/// reg(a) (1/3) * 1 * 1
4746/// reg(b) 1 * (1/3) * (1/2)
4747/// reg({0,+,1}) (2/3) * (2/3) * (1/2)
4748/// reg({-1,+,1}) (2/3) * (2/3) * 1
4749/// reg({a,+,1}) (2/3) * 1 * 1
4750/// reg({b,+,1}) 1 * (2/3) * (2/3)
4751/// reg(c) 1 * 1 * 0
4752///
4753/// Now count registers number mathematical expectation for each formula:
4754/// Note that for each use we exclude probability if not selecting for the use.
4755/// For example for Use1 probability for reg(a) would be just 1 * 1 (excluding
4756/// probabilty 1/3 of not selecting for Use1).
4757/// Use1:
4758/// reg(a) + reg({0,+,1}) 1 + 1/3 -- to be deleted
4759/// reg(a) + reg({-1,+,1}) + 1 1 + 4/9 -- to be deleted
4760/// reg({a,+,1}) 1
4761/// Use2:
4762/// reg(b) + reg({0,+,1}) 1/2 + 1/3 -- to be deleted
4763/// reg(b) + reg({-1,+,1}) + 1 1/2 + 2/3 -- to be deleted
4764/// reg({b,+,1}) 2/3
4765/// Use3:
4766/// reg(c) + reg(b) + reg({0,+,1}) 1 + 1/3 + 4/9 -- to be deleted
4767/// reg(c) + reg({b,+,1}) 1 + 2/3
4768void LSRInstance::NarrowSearchSpaceByDeletingCostlyFormulas() {
4769 if (EstimateSearchSpaceComplexity() < ComplexityLimit)
4770 return;
4771 // Ok, we have too many of formulae on our hands to conveniently handle.
4772 // Use a rough heuristic to thin out the list.
4773
4774 // Set of Regs wich will be 100% used in final solution.
4775 // Used in each formula of a solution (in example above this is reg(c)).
4776 // We can skip them in calculations.
4777 SmallPtrSet<const SCEV *, 4> UniqRegs;
4778 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)
;
4779
4780 // Map each register to probability of not selecting
4781 DenseMap <const SCEV *, float> RegNumMap;
4782 for (const SCEV *Reg : RegUses) {
4783 if (UniqRegs.count(Reg))
4784 continue;
4785 float PNotSel = 1;
4786 for (const LSRUse &LU : Uses) {
4787 if (!LU.Regs.count(Reg))
4788 continue;
4789 float P = LU.getNotSelectedProbability(Reg);
4790 if (P != 0.0)
4791 PNotSel *= P;
4792 else
4793 UniqRegs.insert(Reg);
4794 }
4795 RegNumMap.insert(std::make_pair(Reg, PNotSel));
4796 }
4797
4798 LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "Narrowing the search space by deleting costly formulas\n"
; } } while (false)
4799 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)
;
4800
4801 // Delete formulas where registers number expectation is high.
4802 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4803 LSRUse &LU = Uses[LUIdx];
4804 // If nothing to delete - continue.
4805 if (LU.Formulae.size() < 2)
4806 continue;
4807 // This is temporary solution to test performance. Float should be
4808 // replaced with round independent type (based on integers) to avoid
4809 // different results for different target builds.
4810 float FMinRegNum = LU.Formulae[0].getNumRegs();
4811 float FMinARegNum = LU.Formulae[0].getNumRegs();
4812 size_t MinIdx = 0;
4813 for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {
4814 Formula &F = LU.Formulae[i];
4815 float FRegNum = 0;
4816 float FARegNum = 0;
4817 for (const SCEV *BaseReg : F.BaseRegs) {
4818 if (UniqRegs.count(BaseReg))
4819 continue;
4820 FRegNum += RegNumMap[BaseReg] / LU.getNotSelectedProbability(BaseReg);
4821 if (isa<SCEVAddRecExpr>(BaseReg))
4822 FARegNum +=
4823 RegNumMap[BaseReg] / LU.getNotSelectedProbability(BaseReg);
4824 }
4825 if (const SCEV *ScaledReg = F.ScaledReg) {
4826 if (!UniqRegs.count(ScaledReg)) {
4827 FRegNum +=
4828 RegNumMap[ScaledReg] / LU.getNotSelectedProbability(ScaledReg);
4829 if (isa<SCEVAddRecExpr>(ScaledReg))
4830 FARegNum +=
4831 RegNumMap[ScaledReg] / LU.getNotSelectedProbability(ScaledReg);
4832 }
4833 }
4834 if (FMinRegNum > FRegNum ||
4835 (FMinRegNum == FRegNum && FMinARegNum > FARegNum)) {
4836 FMinRegNum = FRegNum;
4837 FMinARegNum = FARegNum;
4838 MinIdx = i;
4839 }
4840 }
4841 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)
4842 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)
;
4843 if (MinIdx != 0)
4844 std::swap(LU.Formulae[MinIdx], LU.Formulae[0]);
4845 while (LU.Formulae.size() != 1) {
4846 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
)
4847 dbgs() << '\n')do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << " Deleting "; LU.Formulae
.back().print(dbgs()); dbgs() << '\n'; } } while (false
)
;
4848 LU.Formulae.pop_back();
4849 }
4850 LU.RecomputeRegs(LUIdx, RegUses);
4851 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4851, __PRETTY_FUNCTION__))
;
4852 Formula &F = LU.Formulae[0];
4853 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)
;
4854 // When we choose the formula, the regs become unique.
4855 UniqRegs.insert(F.BaseRegs.begin(), F.BaseRegs.end());
4856 if (F.ScaledReg)
4857 UniqRegs.insert(F.ScaledReg);
4858 }
4859 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)
;
4860}
4861
4862/// Pick a register which seems likely to be profitable, and then in any use
4863/// which has any reference to that register, delete all formulae which do not
4864/// reference that register.
4865void LSRInstance::NarrowSearchSpaceByPickingWinnerRegs() {
4866 // With all other options exhausted, loop until the system is simple
4867 // enough to handle.
4868 SmallPtrSet<const SCEV *, 4> Taken;
4869 while (EstimateSearchSpaceComplexity() >= ComplexityLimit) {
4870 // Ok, we have too many of formulae on our hands to conveniently handle.
4871 // Use a rough heuristic to thin out the list.
4872 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)
;
4873
4874 // Pick the register which is used by the most LSRUses, which is likely
4875 // to be a good reuse register candidate.
4876 const SCEV *Best = nullptr;
4877 unsigned BestNum = 0;
4878 for (const SCEV *Reg : RegUses) {
4879 if (Taken.count(Reg))
4880 continue;
4881 if (!Best) {
4882 Best = Reg;
4883 BestNum = RegUses.getUsedByIndices(Reg).count();
4884 } else {
4885 unsigned Count = RegUses.getUsedByIndices(Reg).count();
4886 if (Count > BestNum) {
4887 Best = Reg;
4888 BestNum = Count;
4889 }
4890 }
4891 }
4892 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4892, __PRETTY_FUNCTION__))
;
4893
4894 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)
4895 << " 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)
;
4896 Taken.insert(Best);
4897
4898 // In any use with formulae which references this register, delete formulae
4899 // which don't reference it.
4900 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
4901 LSRUse &LU = Uses[LUIdx];
4902 if (!LU.Regs.count(Best)) continue;
4903
4904 bool Any = false;
4905 for (size_t i = 0, e = LU.Formulae.size(); i != e; ++i) {
4906 Formula &F = LU.Formulae[i];
4907 if (!F.referencesReg(Best)) {
4908 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)
;
4909 LU.DeleteFormula(F);
4910 --e;
4911 --i;
4912 Any = true;
4913 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 4913, __PRETTY_FUNCTION__))
;
4914 continue;
4915 }
4916 }
4917
4918 if (Any)
4919 LU.RecomputeRegs(LUIdx, RegUses);
4920 }
4921
4922 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)
;
4923 }
4924}
4925
4926/// If there are an extraordinary number of formulae to choose from, use some
4927/// rough heuristics to prune down the number of formulae. This keeps the main
4928/// solver from taking an extraordinary amount of time in some worst-case
4929/// scenarios.
4930void LSRInstance::NarrowSearchSpaceUsingHeuristics() {
4931 NarrowSearchSpaceByDetectingSupersets();
4932 NarrowSearchSpaceByCollapsingUnrolledCode();
4933 NarrowSearchSpaceByRefilteringUndesirableDedicatedRegisters();
4934 if (FilterSameScaledReg)
4935 NarrowSearchSpaceByFilterFormulaWithSameScaledReg();
4936 NarrowSearchSpaceByFilterPostInc();
4937 if (LSRExpNarrow)
4938 NarrowSearchSpaceByDeletingCostlyFormulas();
4939 else
4940 NarrowSearchSpaceByPickingWinnerRegs();
4941}
4942
4943/// This is the recursive solver.
4944void LSRInstance::SolveRecurse(SmallVectorImpl<const Formula *> &Solution,
4945 Cost &SolutionCost,
4946 SmallVectorImpl<const Formula *> &Workspace,
4947 const Cost &CurCost,
4948 const SmallPtrSet<const SCEV *, 16> &CurRegs,
4949 DenseSet<const SCEV *> &VisitedRegs) const {
4950 // Some ideas:
4951 // - prune more:
4952 // - use more aggressive filtering
4953 // - sort the formula so that the most profitable solutions are found first
4954 // - sort the uses too
4955 // - search faster:
4956 // - don't compute a cost, and then compare. compare while computing a cost
4957 // and bail early.
4958 // - track register sets with SmallBitVector
4959
4960 const LSRUse &LU = Uses[Workspace.size()];
4961
4962 // If this use references any register that's already a part of the
4963 // in-progress solution, consider it a requirement that a formula must
4964 // reference that register in order to be considered. This prunes out
4965 // unprofitable searching.
4966 SmallSetVector<const SCEV *, 4> ReqRegs;
4967 for (const SCEV *S : CurRegs)
4968 if (LU.Regs.count(S))
4969 ReqRegs.insert(S);
4970
4971 SmallPtrSet<const SCEV *, 16> NewRegs;
4972 Cost NewCost(L, SE, TTI);
4973 for (const Formula &F : LU.Formulae) {
4974 // Ignore formulae which may not be ideal in terms of register reuse of
4975 // ReqRegs. The formula should use all required registers before
4976 // introducing new ones.
4977 // This can sometimes (notably when trying to favour postinc) lead to
4978 // sub-optimial decisions. There it is best left to the cost modelling to
4979 // get correct.
4980 if (!TTI.shouldFavorPostInc() || LU.Kind != LSRUse::Address) {
4981 int NumReqRegsToFind = std::min(F.getNumRegs(), ReqRegs.size());
4982 for (const SCEV *Reg : ReqRegs) {
4983 if ((F.ScaledReg && F.ScaledReg == Reg) ||
4984 is_contained(F.BaseRegs, Reg)) {
4985 --NumReqRegsToFind;
4986 if (NumReqRegsToFind == 0)
4987 break;
4988 }
4989 }
4990 if (NumReqRegsToFind != 0) {
4991 // If none of the formulae satisfied the required registers, then we could
4992 // clear ReqRegs and try again. Currently, we simply give up in this case.
4993 continue;
4994 }
4995 }
4996
4997 // Evaluate the cost of the current formula. If it's already worse than
4998 // the current best, prune the search at that point.
4999 NewCost = CurCost;
5000 NewRegs = CurRegs;
5001 NewCost.RateFormula(F, NewRegs, VisitedRegs, LU);
5002 if (NewCost.isLess(SolutionCost)) {
5003 Workspace.push_back(&F);
5004 if (Workspace.size() != Uses.size()) {
5005 SolveRecurse(Solution, SolutionCost, Workspace, NewCost,
5006 NewRegs, VisitedRegs);
5007 if (F.getNumRegs() == 1 && Workspace.size() == 1)
5008 VisitedRegs.insert(F.ScaledReg ? F.ScaledReg : F.BaseRegs[0]);
5009 } else {
5010 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)
5011 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)
5012 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)
5013 << "- " << *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)
5014 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)
;
5015
5016 SolutionCost = NewCost;
5017 Solution = Workspace;
5018 }
5019 Workspace.pop_back();
5020 }
5021 }
5022}
5023
5024/// Choose one formula from each use. Return the results in the given Solution
5025/// vector.
5026void LSRInstance::Solve(SmallVectorImpl<const Formula *> &Solution) const {
5027 SmallVector<const Formula *, 8> Workspace;
5028 Cost SolutionCost(L, SE, TTI);
5029 SolutionCost.Lose();
5030 Cost CurCost(L, SE, TTI);
5031 SmallPtrSet<const SCEV *, 16> CurRegs;
5032 DenseSet<const SCEV *> VisitedRegs;
5033 Workspace.reserve(Uses.size());
5034
5035 // SolveRecurse does all the work.
5036 SolveRecurse(Solution, SolutionCost, Workspace, CurCost,
5037 CurRegs, VisitedRegs);
5038 if (Solution.empty()) {
5039 LLVM_DEBUG(dbgs() << "\nNo Satisfactory Solution\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nNo Satisfactory Solution\n"
; } } while (false)
;
5040 return;
5041 }
5042
5043 // Ok, we've now made all our decisions.
5044 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
)
5045 "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
)
5046 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
)
5047 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
)
5048 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
)
5049 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
)
5050 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
)
5051 " ";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
)
5052 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
)
5053 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
)
5054 })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
)
;
5055
5056 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5056, __PRETTY_FUNCTION__))
;
5057}
5058
5059/// Helper for AdjustInsertPositionForExpand. Climb up the dominator tree far as
5060/// we can go while still being dominated by the input positions. This helps
5061/// canonicalize the insert position, which encourages sharing.
5062BasicBlock::iterator
5063LSRInstance::HoistInsertPosition(BasicBlock::iterator IP,
5064 const SmallVectorImpl<Instruction *> &Inputs)
5065 const {
5066 Instruction *Tentative = &*IP;
5067 while (true) {
5068 bool AllDominate = true;
5069 Instruction *BetterPos = nullptr;
5070 // Don't bother attempting to insert before a catchswitch, their basic block
5071 // cannot have other non-PHI instructions.
5072 if (isa<CatchSwitchInst>(Tentative))
5073 return IP;
5074
5075 for (Instruction *Inst : Inputs) {
5076 if (Inst == Tentative || !DT.dominates(Inst, Tentative)) {
5077 AllDominate = false;
5078 break;
5079 }
5080 // Attempt to find an insert position in the middle of the block,
5081 // instead of at the end, so that it can be used for other expansions.
5082 if (Tentative->getParent() == Inst->getParent() &&
5083 (!BetterPos || !DT.dominates(Inst, BetterPos)))
5084 BetterPos = &*std::next(BasicBlock::iterator(Inst));
5085 }
5086 if (!AllDominate)
5087 break;
5088 if (BetterPos)
5089 IP = BetterPos->getIterator();
5090 else
5091 IP = Tentative->getIterator();
5092
5093 const Loop *IPLoop = LI.getLoopFor(IP->getParent());
5094 unsigned IPLoopDepth = IPLoop ? IPLoop->getLoopDepth() : 0;
5095
5096 BasicBlock *IDom;
5097 for (DomTreeNode *Rung = DT.getNode(IP->getParent()); ; ) {
5098 if (!Rung) return IP;
5099 Rung = Rung->getIDom();
5100 if (!Rung) return IP;
5101 IDom = Rung->getBlock();
5102
5103 // Don't climb into a loop though.
5104 const Loop *IDomLoop = LI.getLoopFor(IDom);
5105 unsigned IDomDepth = IDomLoop ? IDomLoop->getLoopDepth() : 0;
5106 if (IDomDepth <= IPLoopDepth &&
5107 (IDomDepth != IPLoopDepth || IDomLoop == IPLoop))
5108 break;
5109 }
5110
5111 Tentative = IDom->getTerminator();
5112 }
5113
5114 return IP;
5115}
5116
5117/// Determine an input position which will be dominated by the operands and
5118/// which will dominate the result.
5119BasicBlock::iterator
5120LSRInstance::AdjustInsertPositionForExpand(BasicBlock::iterator LowestIP,
5121 const LSRFixup &LF,
5122 const LSRUse &LU,
5123 SCEVExpander &Rewriter) const {
5124 // Collect some instructions which must be dominated by the
5125 // expanding replacement. These must be dominated by any operands that
5126 // will be required in the expansion.
5127 SmallVector<Instruction *, 4> Inputs;
5128 if (Instruction *I = dyn_cast<Instruction>(LF.OperandValToReplace))
5129 Inputs.push_back(I);
5130 if (LU.Kind == LSRUse::ICmpZero)
5131 if (Instruction *I =
5132 dyn_cast<Instruction>(cast<ICmpInst>(LF.UserInst)->getOperand(1)))
5133 Inputs.push_back(I);
5134 if (LF.PostIncLoops.count(L)) {
5135 if (LF.isUseFullyOutsideLoop(L))
5136 Inputs.push_back(L->getLoopLatch()->getTerminator());
5137 else
5138 Inputs.push_back(IVIncInsertPos);
5139 }
5140 // The expansion must also be dominated by the increment positions of any
5141 // loops it for which it is using post-inc mode.
5142 for (const Loop *PIL : LF.PostIncLoops) {
5143 if (PIL == L) continue;
5144
5145 // Be dominated by the loop exit.
5146 SmallVector<BasicBlock *, 4> ExitingBlocks;
5147 PIL->getExitingBlocks(ExitingBlocks);
5148 if (!ExitingBlocks.empty()) {
5149 BasicBlock *BB = ExitingBlocks[0];
5150 for (unsigned i = 1, e = ExitingBlocks.size(); i != e; ++i)
5151 BB = DT.findNearestCommonDominator(BB, ExitingBlocks[i]);
5152 Inputs.push_back(BB->getTerminator());
5153 }
5154 }
5155
5156 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5158, __PRETTY_FUNCTION__))
5157 && !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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5158, __PRETTY_FUNCTION__))
5158 "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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5158, __PRETTY_FUNCTION__))
;
5159
5160 // Then, climb up the immediate dominator tree as far as we can go while
5161 // still being dominated by the input positions.
5162 BasicBlock::iterator IP = HoistInsertPosition(LowestIP, Inputs);
5163
5164 // Don't insert instructions before PHI nodes.
5165 while (isa<PHINode>(IP)) ++IP;
5166
5167 // Ignore landingpad instructions.
5168 while (IP->isEHPad()) ++IP;
5169
5170 // Ignore debug intrinsics.
5171 while (isa<DbgInfoIntrinsic>(IP)) ++IP;
5172
5173 // Set IP below instructions recently inserted by SCEVExpander. This keeps the
5174 // IP consistent across expansions and allows the previously inserted
5175 // instructions to be reused by subsequent expansion.
5176 while (Rewriter.isInsertedInstruction(&*IP) && IP != LowestIP)
5177 ++IP;
5178
5179 return IP;
5180}
5181
5182/// Emit instructions for the leading candidate expression for this LSRUse (this
5183/// is called "expanding").
5184Value *LSRInstance::Expand(const LSRUse &LU, const LSRFixup &LF,
5185 const Formula &F, BasicBlock::iterator IP,
5186 SCEVExpander &Rewriter,
5187 SmallVectorImpl<WeakTrackingVH> &DeadInsts) const {
5188 if (LU.RigidFormula)
5189 return LF.OperandValToReplace;
5190
5191 // Determine an input position which will be dominated by the operands and
5192 // which will dominate the result.
5193 IP = AdjustInsertPositionForExpand(IP, LF, LU, Rewriter);
5194 Rewriter.setInsertPoint(&*IP);
5195
5196 // Inform the Rewriter if we have a post-increment use, so that it can
5197 // perform an advantageous expansion.
5198 Rewriter.setPostInc(LF.PostIncLoops);
5199
5200 // This is the type that the user actually needs.
5201 Type *OpTy = LF.OperandValToReplace->getType();
5202 // This will be the type that we'll initially expand to.
5203 Type *Ty = F.getType();
5204 if (!Ty)
5205 // No type known; just expand directly to the ultimate type.
5206 Ty = OpTy;
5207 else if (SE.getEffectiveSCEVType(Ty) == SE.getEffectiveSCEVType(OpTy))
5208 // Expand directly to the ultimate type if it's the right size.
5209 Ty = OpTy;
5210 // This is the type to do integer arithmetic in.
5211 Type *IntTy = SE.getEffectiveSCEVType(Ty);
5212
5213 // Build up a list of operands to add together to form the full base.
5214 SmallVector<const SCEV *, 8> Ops;
5215
5216 // Expand the BaseRegs portion.
5217 for (const SCEV *Reg : F.BaseRegs) {
5218 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5218, __PRETTY_FUNCTION__))
;
5219
5220 // If we're expanding for a post-inc user, make the post-inc adjustment.
5221 Reg = denormalizeForPostIncUse(Reg, LF.PostIncLoops, SE);
5222 Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, nullptr)));
5223 }
5224
5225 // Expand the ScaledReg portion.
5226 Value *ICmpScaledV = nullptr;
5227 if (F.Scale != 0) {
5228 const SCEV *ScaledS = F.ScaledReg;
5229
5230 // If we're expanding for a post-inc user, make the post-inc adjustment.
5231 PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops);
5232 ScaledS = denormalizeForPostIncUse(ScaledS, Loops, SE);
5233
5234 if (LU.Kind == LSRUse::ICmpZero) {
5235 // Expand ScaleReg as if it was part of the base regs.
5236 if (F.Scale == 1)
5237 Ops.push_back(
5238 SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr)));
5239 else {
5240 // An interesting way of "folding" with an icmp is to use a negated
5241 // scale, which we'll implement by inserting it into the other operand
5242 // of the icmp.
5243 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5244, __PRETTY_FUNCTION__))
5244 "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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5244, __PRETTY_FUNCTION__))
;
5245 ICmpScaledV = Rewriter.expandCodeFor(ScaledS, nullptr);
5246 }
5247 } else {
5248 // Otherwise just expand the scaled register and an explicit scale,
5249 // which is expected to be matched as part of the address.
5250
5251 // Flush the operand list to suppress SCEVExpander hoisting address modes.
5252 // Unless the addressing mode will not be folded.
5253 if (!Ops.empty() && LU.Kind == LSRUse::Address &&
5254 isAMCompletelyFolded(TTI, LU, F)) {
5255 Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), nullptr);
5256 Ops.clear();
5257 Ops.push_back(SE.getUnknown(FullV));
5258 }
5259 ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr));
5260 if (F.Scale != 1)
5261 ScaledS =
5262 SE.getMulExpr(ScaledS, SE.getConstant(ScaledS->getType(), F.Scale));
5263 Ops.push_back(ScaledS);
5264 }
5265 }
5266
5267 // Expand the GV portion.
5268 if (F.BaseGV) {
5269 // Flush the operand list to suppress SCEVExpander hoisting.
5270 if (!Ops.empty()) {
5271 Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty);
5272 Ops.clear();
5273 Ops.push_back(SE.getUnknown(FullV));
5274 }
5275 Ops.push_back(SE.getUnknown(F.BaseGV));
5276 }
5277
5278 // Flush the operand list to suppress SCEVExpander hoisting of both folded and
5279 // unfolded offsets. LSR assumes they both live next to their uses.
5280 if (!Ops.empty()) {
5281 Value *FullV = Rewriter.expandCodeFor(SE.getAddExpr(Ops), Ty);
5282 Ops.clear();
5283 Ops.push_back(SE.getUnknown(FullV));
5284 }
5285
5286 // Expand the immediate portion.
5287 int64_t Offset = (uint64_t)F.BaseOffset + LF.Offset;
5288 if (Offset != 0) {
5289 if (LU.Kind == LSRUse::ICmpZero) {
5290 // The other interesting way of "folding" with an ICmpZero is to use a
5291 // negated immediate.
5292 if (!ICmpScaledV)
5293 ICmpScaledV = ConstantInt::get(IntTy, -(uint64_t)Offset);
5294 else {
5295 Ops.push_back(SE.getUnknown(ICmpScaledV));
5296 ICmpScaledV = ConstantInt::get(IntTy, Offset);
5297 }
5298 } else {
5299 // Just add the immediate values. These again are expected to be matched
5300 // as part of the address.
5301 Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy, Offset)));
5302 }
5303 }
5304
5305 // Expand the unfolded offset portion.
5306 int64_t UnfoldedOffset = F.UnfoldedOffset;
5307 if (UnfoldedOffset != 0) {
5308 // Just add the immediate values.
5309 Ops.push_back(SE.getUnknown(ConstantInt::getSigned(IntTy,
5310 UnfoldedOffset)));
5311 }
5312
5313 // Emit instructions summing all the operands.
5314 const SCEV *FullS = Ops.empty() ?
5315 SE.getConstant(IntTy, 0) :
5316 SE.getAddExpr(Ops);
5317 Value *FullV = Rewriter.expandCodeFor(FullS, Ty);
5318
5319 // We're done expanding now, so reset the rewriter.
5320 Rewriter.clearPostInc();
5321
5322 // An ICmpZero Formula represents an ICmp which we're handling as a
5323 // comparison against zero. Now that we've expanded an expression for that
5324 // form, update the ICmp's other operand.
5325 if (LU.Kind == LSRUse::ICmpZero) {
5326 ICmpInst *CI = cast<ICmpInst>(LF.UserInst);
5327 if (auto *OperandIsInstr = dyn_cast<Instruction>(CI->getOperand(1)))
5328 DeadInsts.emplace_back(OperandIsInstr);
5329 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5330, __PRETTY_FUNCTION__))
5330 "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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5330, __PRETTY_FUNCTION__))
;
5331 if (F.Scale == -1) {
5332 if (ICmpScaledV->getType() != OpTy) {
5333 Instruction *Cast =
5334 CastInst::Create(CastInst::getCastOpcode(ICmpScaledV, false,
5335 OpTy, false),
5336 ICmpScaledV, OpTy, "tmp", CI);
5337 ICmpScaledV = Cast;
5338 }
5339 CI->setOperand(1, ICmpScaledV);
5340 } else {
5341 // A scale of 1 means that the scale has been expanded as part of the
5342 // base regs.
5343 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5345, __PRETTY_FUNCTION__))
5344 "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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5345, __PRETTY_FUNCTION__))
5345 "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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5345, __PRETTY_FUNCTION__))
;
5346 Constant *C = ConstantInt::getSigned(SE.getEffectiveSCEVType(OpTy),
5347 -(uint64_t)Offset);
5348 if (C->getType() != OpTy)
5349 C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
5350 OpTy, false),
5351 C, OpTy);
5352
5353 CI->setOperand(1, C);
5354 }
5355 }
5356
5357 return FullV;
5358}
5359
5360/// Helper for Rewrite. PHI nodes are special because the use of their operands
5361/// effectively happens in their predecessor blocks, so the expression may need
5362/// to be expanded in multiple places.
5363void LSRInstance::RewriteForPHI(
5364 PHINode *PN, const LSRUse &LU, const LSRFixup &LF, const Formula &F,
5365 SCEVExpander &Rewriter, SmallVectorImpl<WeakTrackingVH> &DeadInsts) const {
5366 DenseMap<BasicBlock *, Value *> Inserted;
5367 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
5368 if (PN->getIncomingValue(i) == LF.OperandValToReplace) {
3
Assuming pointer value is null
4
Taking true branch
5369 bool needUpdateFixups = false;
5370 BasicBlock *BB = PN->getIncomingBlock(i);
5371
5372 // If this is a critical edge, split the edge so that we do not insert
5373 // the code on all predecessor/successor paths. We do this unless this
5374 // is the canonical backedge for this loop, which complicates post-inc
5375 // users.
5376 if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 &&
5
Assuming 'e' is equal to 1
6
Taking false branch
5377 !isa<IndirectBrInst>(BB->getTerminator()) &&
5378 !isa<CatchSwitchInst>(BB->getTerminator())) {
5379 BasicBlock *Parent = PN->getParent();
5380 Loop *PNLoop = LI.getLoopFor(Parent);
5381 if (!PNLoop || Parent != PNLoop->getHeader()) {
5382 // Split the critical edge.
5383 BasicBlock *NewBB = nullptr;
5384 if (!Parent->isLandingPad()) {
5385 NewBB =
5386 SplitCriticalEdge(BB, Parent,
5387 CriticalEdgeSplittingOptions(&DT, &LI, MSSAU)
5388 .setMergeIdenticalEdges()
5389 .setKeepOneInputPHIs());
5390 } else {
5391 SmallVector<BasicBlock*, 2> NewBBs;
5392 SplitLandingPadPredecessors(Parent, BB, "", "", NewBBs, &DT, &LI);
5393 NewBB = NewBBs[0];
5394 }
5395 // If NewBB==NULL, then SplitCriticalEdge refused to split because all
5396 // phi predecessors are identical. The simple thing to do is skip
5397 // splitting in this case rather than complicate the API.
5398 if (NewBB) {
5399 // If PN is outside of the loop and BB is in the loop, we want to
5400 // move the block to be immediately before the PHI block, not
5401 // immediately after BB.
5402 if (L->contains(BB) && !L->contains(PN))
5403 NewBB->moveBefore(PN->getParent());
5404
5405 // Splitting the edge can reduce the number of PHI entries we have.
5406 e = PN->getNumIncomingValues();
5407 BB = NewBB;
5408 i = PN->getBasicBlockIndex(BB);
5409
5410 needUpdateFixups = true;
5411 }
5412 }
5413 }
5414
5415 std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair =
5416 Inserted.insert(std::make_pair(BB, static_cast<Value *>(nullptr)));
5417 if (!Pair.second)
7
Assuming field 'second' is true
8
Taking false branch
5418 PN->setIncomingValue(i, Pair.first->second);
5419 else {
5420 Value *FullV = Expand(LU, LF, F, BB->getTerminator()->getIterator(),
5421 Rewriter, DeadInsts);
5422
5423 // If this is reuse-by-noop-cast, insert the noop cast.
5424 Type *OpTy = LF.OperandValToReplace->getType();
9
Called C++ object pointer is null
5425 if (FullV->getType() != OpTy)
5426 FullV =
5427 CastInst::Create(CastInst::getCastOpcode(FullV, false,
5428 OpTy, false),
5429 FullV, LF.OperandValToReplace->getType(),
5430 "tmp", BB->getTerminator());
5431
5432 PN->setIncomingValue(i, FullV);
5433 Pair.first->second = FullV;
5434 }
5435
5436 // If LSR splits critical edge and phi node has other pending
5437 // fixup operands, we need to update those pending fixups. Otherwise
5438 // formulae will not be implemented completely and some instructions
5439 // will not be eliminated.
5440 if (needUpdateFixups) {
5441 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx)
5442 for (LSRFixup &Fixup : Uses[LUIdx].Fixups)
5443 // If fixup is supposed to rewrite some operand in the phi
5444 // that was just updated, it may be already moved to
5445 // another phi node. Such fixup requires update.
5446 if (Fixup.UserInst == PN) {
5447 // Check if the operand we try to replace still exists in the
5448 // original phi.
5449 bool foundInOriginalPHI = false;
5450 for (const auto &val : PN->incoming_values())
5451 if (val == Fixup.OperandValToReplace) {
5452 foundInOriginalPHI = true;
5453 break;
5454 }
5455
5456 // If fixup operand found in original PHI - nothing to do.
5457 if (foundInOriginalPHI)
5458 continue;
5459
5460 // Otherwise it might be moved to another PHI and requires update.
5461 // If fixup operand not found in any of the incoming blocks that
5462 // means we have already rewritten it - nothing to do.
5463 for (const auto &Block : PN->blocks())
5464 for (BasicBlock::iterator I = Block->begin(); isa<PHINode>(I);
5465 ++I) {
5466 PHINode *NewPN = cast<PHINode>(I);
5467 for (const auto &val : NewPN->incoming_values())
5468 if (val == Fixup.OperandValToReplace)
5469 Fixup.UserInst = NewPN;
5470 }
5471 }
5472 }
5473 }
5474}
5475
5476/// Emit instructions for the leading candidate expression for this LSRUse (this
5477/// is called "expanding"), and update the UserInst to reference the newly
5478/// expanded value.
5479void LSRInstance::Rewrite(const LSRUse &LU, const LSRFixup &LF,
5480 const Formula &F, SCEVExpander &Rewriter,
5481 SmallVectorImpl<WeakTrackingVH> &DeadInsts) const {
5482 // First, find an insertion point that dominates UserInst. For PHI nodes,
5483 // find the nearest block which dominates all the relevant uses.
5484 if (PHINode *PN = dyn_cast<PHINode>(LF.UserInst)) {
5485 RewriteForPHI(PN, LU, LF, F, Rewriter, DeadInsts);
5486 } else {
5487 Value *FullV =
5488 Expand(LU, LF, F, LF.UserInst->getIterator(), Rewriter, DeadInsts);
5489
5490 // If this is reuse-by-noop-cast, insert the noop cast.
5491 Type *OpTy = LF.OperandValToReplace->getType();
5492 if (FullV->getType() != OpTy) {
5493 Instruction *Cast =
5494 CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false),
5495 FullV, OpTy, "tmp", LF.UserInst);
5496 FullV = Cast;
5497 }
5498
5499 // Update the user. ICmpZero is handled specially here (for now) because
5500 // Expand may have updated one of the operands of the icmp already, and
5501 // its new value may happen to be equal to LF.OperandValToReplace, in
5502 // which case doing replaceUsesOfWith leads to replacing both operands
5503 // with the same value. TODO: Reorganize this.
5504 if (LU.Kind == LSRUse::ICmpZero)
5505 LF.UserInst->setOperand(0, FullV);
5506 else
5507 LF.UserInst->replaceUsesOfWith(LF.OperandValToReplace, FullV);
5508 }
5509
5510 if (auto *OperandIsInstr = dyn_cast<Instruction>(LF.OperandValToReplace))
5511 DeadInsts.emplace_back(OperandIsInstr);
5512}
5513
5514/// Rewrite all the fixup locations with new values, following the chosen
5515/// solution.
5516void LSRInstance::ImplementSolution(
5517 const SmallVectorImpl<const Formula *> &Solution) {
5518 // Keep track of instructions we may have made dead, so that
5519 // we can remove them after we are done working.
5520 SmallVector<WeakTrackingVH, 16> DeadInsts;
5521
5522 SCEVExpander Rewriter(SE, L->getHeader()->getModule()->getDataLayout(), "lsr",
5523 false);
5524#ifndef NDEBUG
5525 Rewriter.setDebugType(DEBUG_TYPE"loop-reduce");
5526#endif
5527 Rewriter.disableCanonicalMode();
5528 Rewriter.enableLSRMode();
5529 Rewriter.setIVIncInsertPos(L, IVIncInsertPos);
5530
5531 // Mark phi nodes that terminate chains so the expander tries to reuse them.
5532 for (const IVChain &Chain : IVChainVec) {
5533 if (PHINode *PN = dyn_cast<PHINode>(Chain.tailUserInst()))
5534 Rewriter.setChainedPhi(PN);
5535 }
5536
5537 // Expand the new value definitions and update the users.
5538 for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx)
5539 for (const LSRFixup &Fixup : Uses[LUIdx].Fixups) {
5540 Rewrite(Uses[LUIdx], Fixup, *Solution[LUIdx], Rewriter, DeadInsts);
5541 Changed = true;
5542 }
5543
5544 for (const IVChain &Chain : IVChainVec) {
5545 GenerateIVChain(Chain, Rewriter, DeadInsts);
5546 Changed = true;
5547 }
5548 // Clean up after ourselves. This must be done before deleting any
5549 // instructions.
5550 Rewriter.clear();
5551
5552 Changed |= RecursivelyDeleteTriviallyDeadInstructionsPermissive(DeadInsts,
5553 &TLI, MSSAU);
5554}
5555
5556LSRInstance::LSRInstance(Loop *L, IVUsers &IU, ScalarEvolution &SE,
5557 DominatorTree &DT, LoopInfo &LI,
5558 const TargetTransformInfo &TTI, AssumptionCache &AC,
5559 TargetLibraryInfo &TLI, MemorySSAUpdater *MSSAU)
5560 : IU(IU), SE(SE), DT(DT), LI(LI), AC(AC), TLI(TLI), TTI(TTI), L(L),
5561 MSSAU(MSSAU), FavorBackedgeIndex(EnableBackedgeIndexing &&
5562 TTI.shouldFavorBackedgeIndex(L)) {
5563 // If LoopSimplify form is not available, stay out of trouble.
5564 if (!L->isLoopSimplifyForm())
5565 return;
5566
5567 // If there's no interesting work to be done, bail early.
5568 if (IU.empty()) return;
5569
5570 // If there's too much analysis to be done, bail early. We won't be able to
5571 // model the problem anyway.
5572 unsigned NumUsers = 0;
5573 for (const IVStrideUse &U : IU) {
5574 if (++NumUsers > MaxIVUsers) {
5575 (void)U;
5576 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)
5577 << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR skipping loop, too many IV Users in "
<< U << "\n"; } } while (false)
;
5578 return;
5579 }
5580 // Bail out if we have a PHI on an EHPad that gets a value from a
5581 // CatchSwitchInst. Because the CatchSwitchInst cannot be split, there is
5582 // no good place to stick any instructions.
5583 if (auto *PN = dyn_cast<PHINode>(U.getUser())) {
5584 auto *FirstNonPHI = PN->getParent()->getFirstNonPHI();
5585 if (isa<FuncletPadInst>(FirstNonPHI) ||
5586 isa<CatchSwitchInst>(FirstNonPHI))
5587 for (BasicBlock *PredBB : PN->blocks())
5588 if (isa<CatchSwitchInst>(PredBB->getFirstNonPHI()))
5589 return;
5590 }
5591 }
5592
5593#ifndef NDEBUG
5594 // All dominating loops must have preheaders, or SCEVExpander may not be able
5595 // to materialize an AddRecExpr whose Start is an outer AddRecExpr.
5596 //
5597 // IVUsers analysis should only create users that are dominated by simple loop
5598 // headers. Since this loop should dominate all of its users, its user list
5599 // should be empty if this loop itself is not within a simple loop nest.
5600 for (DomTreeNode *Rung = DT.getNode(L->getLoopPreheader());
5601 Rung; Rung = Rung->getIDom()) {
5602 BasicBlock *BB = Rung->getBlock();
5603 const Loop *DomLoop = LI.getLoopFor(BB);
5604 if (DomLoop && DomLoop->getHeader() == BB) {
5605 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5605, __PRETTY_FUNCTION__))
;
5606 }
5607 }
5608#endif // DEBUG
5609
5610 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)
5611 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)
5612 dbgs() << ":\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "\nLSR on loop "; L->getHeader
()->printAsOperand(dbgs(), false); dbgs() << ":\n"; }
} while (false)
;
5613
5614 // First, perform some low-level loop optimizations.
5615 OptimizeShadowIV();
5616 OptimizeLoopTermCond();
5617
5618 // If loop preparation eliminates all interesting IV users, bail.
5619 if (IU.empty()) return;
5620
5621 // Skip nested loops until we can model them better with formulae.
5622 if (!L->isInnermost()) {
5623 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)
;
5624 return;
5625 }
5626
5627 // Start collecting data and preparing for the solver.
5628 CollectChains();
5629 CollectInterestingTypesAndFactors();
5630 CollectFixupsAndInitialFormulae();
5631 CollectLoopInvariantFixupsAndFormulae();
5632
5633 if (Uses.empty())
5634 return;
5635
5636 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
)
5637 print_uses(dbgs()))do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("loop-reduce")) { dbgs() << "LSR found " << Uses
.size() << " uses:\n"; print_uses(dbgs()); } } while (false
)
;
5638
5639 // Now use the reuse data to generate a bunch of interesting ways
5640 // to formulate the values needed for the uses.
5641 GenerateAllReuseFormulae();
5642
5643 FilterOutUndesirableDedicatedRegisters();
5644 NarrowSearchSpaceUsingHeuristics();
5645
5646 SmallVector<const Formula *, 8> Solution;
5647 Solve(Solution);
5648
5649 // Release memory that is no longer needed.
5650 Factors.clear();
5651 Types.clear();
5652 RegUses.clear();
5653
5654 if (Solution.empty())
5655 return;
5656
5657#ifndef NDEBUG
5658 // Formulae should be legal.
5659 for (const LSRUse &LU : Uses) {
5660 for (const Formula &F : LU.Formulae)
5661 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5662, __PRETTY_FUNCTION__))
5662 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-12~++20200927111121+5811d723998/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp"
, 5662, __PRETTY_FUNCTION__))
;
5663 };
5664#endif
5665
5666 // Now that we've decided what we want, make it so.
5667 ImplementSolution(Solution);
5668}
5669
5670#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
5671void LSRInstance::print_factors_and_types(raw_ostream &OS) const {
5672 if (Factors.empty() && Types.empty()) return;
5673
5674 OS << "LSR has identified the following interesting factors and types: ";
5675 bool First = true;
5676
5677 for (int64_t Factor : Factors) {
5678 if (!First) OS << ", ";
5679 First = false;
5680 OS << '*' << Factor;
5681 }
5682
5683 for (Type *Ty : Types) {
5684 if (!First) OS << ", ";
5685 First = false;
5686 OS << '(' << *Ty << ')';
5687 }
5688 OS << '\n';
5689}
5690
5691void LSRInstance::print_fixups(raw_ostream &OS) const {
5692 OS << "LSR is examining the following fixup sites:\n";
5693 for (const LSRUse &LU : Uses)
5694 for (const LSRFixup &LF : LU.Fixups) {
5695 dbgs() << " ";
5696 LF.print(OS);
5697 OS << '\n';
5698 }
5699}
5700
5701void LSRInstance::print_uses(raw_ostream &OS) const {
5702 OS << "LSR is examining the following uses:\n";
5703 for (const LSRUse &LU : Uses) {
5704 dbgs() << " ";
5705 LU.print(OS);
5706 OS << '\n';
5707 for (const Formula &F : LU.Formulae) {
5708 OS << " ";
5709 F.print(OS);
5710 OS << '\n';
5711 }
5712 }
5713}
5714
5715void LSRInstance::print(raw_ostream &OS) const {
5716 print_factors_and_types(OS);
5717 print_fixups(OS);
5718 print_uses(OS);
5719}
5720
5721LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void LSRInstance::dump() const {
5722 print(errs()); errs() << '\n';
5723}
5724#endif
5725
5726namespace {
5727
5728class LoopStrengthReduce : public LoopPass {
5729public:
5730 static char ID; // Pass ID, replacement for typeid
5731
5732 LoopStrengthReduce();
5733
5734private:
5735 bool runOnLoop(Loop *L, LPPassManager &LPM) override;
5736 void getAnalysisUsage(AnalysisUsage &AU) const override;
5737};
5738
5739} // end anonymous namespace
5740
5741LoopStrengthReduce::LoopStrengthReduce() : LoopPass(ID) {
5742 initializeLoopStrengthReducePass(*PassRegistry::getPassRegistry());
5743}
5744
5745void LoopStrengthReduce::getAnalysisUsage(AnalysisUsage &AU) const {
5746 // We split critical edges, so we change the CFG. However, we do update
5747 // many analyses if they are around.
5748 AU.addPreservedID(LoopSimplifyID);
5749
5750 AU.addRequired<LoopInfoWrapperPass>();
5751 AU.addPreserved<LoopInfoWrapperPass>();
5752 AU.addRequiredID(LoopSimplifyID);
5753 AU.addRequired<DominatorTreeWrapperPass>();
5754 AU.addPreserved<DominatorTreeWrapperPass>();
5755 AU.addRequired<ScalarEvolutionWrapperPass>();
5756 AU.addPreserved<ScalarEvolutionWrapperPass>();
5757 AU.addRequired<AssumptionCacheTracker>();
5758 AU.addRequired<TargetLibraryInfoWrapperPass>();