1 //===- AggressiveInstCombine.cpp ------------------------------------------===//
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 file implements the aggressive expression pattern combiner classes.
10 // Currently, it handles expression patterns for:
11 // * Truncate instruction
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/Transforms/AggressiveInstCombine/AggressiveInstCombine.h"
16 #include "AggressiveInstCombineInternal.h"
17 #include "llvm-c/Initialization.h"
18 #include "llvm-c/Transforms/AggressiveInstCombine.h"
19 #include "llvm/ADT/Statistic.h"
20 #include "llvm/Analysis/AliasAnalysis.h"
21 #include "llvm/Analysis/AssumptionCache.h"
22 #include "llvm/Analysis/BasicAliasAnalysis.h"
23 #include "llvm/Analysis/GlobalsModRef.h"
24 #include "llvm/Analysis/TargetLibraryInfo.h"
25 #include "llvm/Analysis/TargetTransformInfo.h"
26 #include "llvm/Analysis/ValueTracking.h"
27 #include "llvm/IR/Dominators.h"
28 #include "llvm/IR/Function.h"
29 #include "llvm/IR/IRBuilder.h"
30 #include "llvm/IR/LegacyPassManager.h"
31 #include "llvm/IR/PatternMatch.h"
32 #include "llvm/InitializePasses.h"
33 #include "llvm/Pass.h"
34 #include "llvm/Transforms/Utils/BuildLibCalls.h"
35 #include "llvm/Transforms/Utils/Local.h"
36
37 using namespace llvm;
38 using namespace PatternMatch;
39
40 namespace llvm {
41 class DataLayout;
42 }
43
44 #define DEBUG_TYPE "aggressive-instcombine"
45
46 STATISTIC(NumAnyOrAllBitsSet, "Number of any/all-bits-set patterns folded");
47 STATISTIC(NumGuardedRotates,
48 "Number of guarded rotates transformed into funnel shifts");
49 STATISTIC(NumGuardedFunnelShifts,
50 "Number of guarded funnel shifts transformed into funnel shifts");
51 STATISTIC(NumPopCountRecognized, "Number of popcount idioms recognized");
52
53 namespace {
54 /// Contains expression pattern combiner logic.
55 /// This class provides both the logic to combine expression patterns and
56 /// combine them. It differs from InstCombiner class in that each pattern
57 /// combiner runs only once as opposed to InstCombine's multi-iteration,
58 /// which allows pattern combiner to have higher complexity than the O(1)
59 /// required by the instruction combiner.
60 class AggressiveInstCombinerLegacyPass : public FunctionPass {
61 public:
62 static char ID; // Pass identification, replacement for typeid
63
AggressiveInstCombinerLegacyPass()64 AggressiveInstCombinerLegacyPass() : FunctionPass(ID) {
65 initializeAggressiveInstCombinerLegacyPassPass(
66 *PassRegistry::getPassRegistry());
67 }
68
69 void getAnalysisUsage(AnalysisUsage &AU) const override;
70
71 /// Run all expression pattern optimizations on the given /p F function.
72 ///
73 /// \param F function to optimize.
74 /// \returns true if the IR is changed.
75 bool runOnFunction(Function &F) override;
76 };
77 } // namespace
78
79 /// Match a pattern for a bitwise funnel/rotate operation that partially guards
80 /// against undefined behavior by branching around the funnel-shift/rotation
81 /// when the shift amount is 0.
foldGuardedFunnelShift(Instruction & I,const DominatorTree & DT)82 static bool foldGuardedFunnelShift(Instruction &I, const DominatorTree &DT) {
83 if (I.getOpcode() != Instruction::PHI || I.getNumOperands() != 2)
84 return false;
85
86 // As with the one-use checks below, this is not strictly necessary, but we
87 // are being cautious to avoid potential perf regressions on targets that
88 // do not actually have a funnel/rotate instruction (where the funnel shift
89 // would be expanded back into math/shift/logic ops).
90 if (!isPowerOf2_32(I.getType()->getScalarSizeInBits()))
91 return false;
92
93 // Match V to funnel shift left/right and capture the source operands and
94 // shift amount.
95 auto matchFunnelShift = [](Value *V, Value *&ShVal0, Value *&ShVal1,
96 Value *&ShAmt) {
97 Value *SubAmt;
98 unsigned Width = V->getType()->getScalarSizeInBits();
99
100 // fshl(ShVal0, ShVal1, ShAmt)
101 // == (ShVal0 << ShAmt) | (ShVal1 >> (Width -ShAmt))
102 if (match(V, m_OneUse(m_c_Or(
103 m_Shl(m_Value(ShVal0), m_Value(ShAmt)),
104 m_LShr(m_Value(ShVal1),
105 m_Sub(m_SpecificInt(Width), m_Value(SubAmt))))))) {
106 if (ShAmt == SubAmt) // TODO: Use m_Specific
107 return Intrinsic::fshl;
108 }
109
110 // fshr(ShVal0, ShVal1, ShAmt)
111 // == (ShVal0 >> ShAmt) | (ShVal1 << (Width - ShAmt))
112 if (match(V,
113 m_OneUse(m_c_Or(m_Shl(m_Value(ShVal0), m_Sub(m_SpecificInt(Width),
114 m_Value(SubAmt))),
115 m_LShr(m_Value(ShVal1), m_Value(ShAmt)))))) {
116 if (ShAmt == SubAmt) // TODO: Use m_Specific
117 return Intrinsic::fshr;
118 }
119
120 return Intrinsic::not_intrinsic;
121 };
122
123 // One phi operand must be a funnel/rotate operation, and the other phi
124 // operand must be the source value of that funnel/rotate operation:
125 // phi [ rotate(RotSrc, ShAmt), FunnelBB ], [ RotSrc, GuardBB ]
126 // phi [ fshl(ShVal0, ShVal1, ShAmt), FunnelBB ], [ ShVal0, GuardBB ]
127 // phi [ fshr(ShVal0, ShVal1, ShAmt), FunnelBB ], [ ShVal1, GuardBB ]
128 PHINode &Phi = cast<PHINode>(I);
129 unsigned FunnelOp = 0, GuardOp = 1;
130 Value *P0 = Phi.getOperand(0), *P1 = Phi.getOperand(1);
131 Value *ShVal0, *ShVal1, *ShAmt;
132 Intrinsic::ID IID = matchFunnelShift(P0, ShVal0, ShVal1, ShAmt);
133 if (IID == Intrinsic::not_intrinsic ||
134 (IID == Intrinsic::fshl && ShVal0 != P1) ||
135 (IID == Intrinsic::fshr && ShVal1 != P1)) {
136 IID = matchFunnelShift(P1, ShVal0, ShVal1, ShAmt);
137 if (IID == Intrinsic::not_intrinsic ||
138 (IID == Intrinsic::fshl && ShVal0 != P0) ||
139 (IID == Intrinsic::fshr && ShVal1 != P0))
140 return false;
141 assert((IID == Intrinsic::fshl || IID == Intrinsic::fshr) &&
142 "Pattern must match funnel shift left or right");
143 std::swap(FunnelOp, GuardOp);
144 }
145
146 // The incoming block with our source operand must be the "guard" block.
147 // That must contain a cmp+branch to avoid the funnel/rotate when the shift
148 // amount is equal to 0. The other incoming block is the block with the
149 // funnel/rotate.
150 BasicBlock *GuardBB = Phi.getIncomingBlock(GuardOp);
151 BasicBlock *FunnelBB = Phi.getIncomingBlock(FunnelOp);
152 Instruction *TermI = GuardBB->getTerminator();
153
154 // Ensure that the shift values dominate each block.
155 if (!DT.dominates(ShVal0, TermI) || !DT.dominates(ShVal1, TermI))
156 return false;
157
158 ICmpInst::Predicate Pred;
159 BasicBlock *PhiBB = Phi.getParent();
160 if (!match(TermI, m_Br(m_ICmp(Pred, m_Specific(ShAmt), m_ZeroInt()),
161 m_SpecificBB(PhiBB), m_SpecificBB(FunnelBB))))
162 return false;
163
164 if (Pred != CmpInst::ICMP_EQ)
165 return false;
166
167 IRBuilder<> Builder(PhiBB, PhiBB->getFirstInsertionPt());
168
169 if (ShVal0 == ShVal1)
170 ++NumGuardedRotates;
171 else
172 ++NumGuardedFunnelShifts;
173
174 // If this is not a rotate then the select was blocking poison from the
175 // 'shift-by-zero' non-TVal, but a funnel shift won't - so freeze it.
176 bool IsFshl = IID == Intrinsic::fshl;
177 if (ShVal0 != ShVal1) {
178 if (IsFshl && !llvm::isGuaranteedNotToBePoison(ShVal1))
179 ShVal1 = Builder.CreateFreeze(ShVal1);
180 else if (!IsFshl && !llvm::isGuaranteedNotToBePoison(ShVal0))
181 ShVal0 = Builder.CreateFreeze(ShVal0);
182 }
183
184 // We matched a variation of this IR pattern:
185 // GuardBB:
186 // %cmp = icmp eq i32 %ShAmt, 0
187 // br i1 %cmp, label %PhiBB, label %FunnelBB
188 // FunnelBB:
189 // %sub = sub i32 32, %ShAmt
190 // %shr = lshr i32 %ShVal1, %sub
191 // %shl = shl i32 %ShVal0, %ShAmt
192 // %fsh = or i32 %shr, %shl
193 // br label %PhiBB
194 // PhiBB:
195 // %cond = phi i32 [ %fsh, %FunnelBB ], [ %ShVal0, %GuardBB ]
196 // -->
197 // llvm.fshl.i32(i32 %ShVal0, i32 %ShVal1, i32 %ShAmt)
198 Function *F = Intrinsic::getDeclaration(Phi.getModule(), IID, Phi.getType());
199 Phi.replaceAllUsesWith(Builder.CreateCall(F, {ShVal0, ShVal1, ShAmt}));
200 return true;
201 }
202
203 /// This is used by foldAnyOrAllBitsSet() to capture a source value (Root) and
204 /// the bit indexes (Mask) needed by a masked compare. If we're matching a chain
205 /// of 'and' ops, then we also need to capture the fact that we saw an
206 /// "and X, 1", so that's an extra return value for that case.
207 struct MaskOps {
208 Value *Root = nullptr;
209 APInt Mask;
210 bool MatchAndChain;
211 bool FoundAnd1 = false;
212
MaskOpsMaskOps213 MaskOps(unsigned BitWidth, bool MatchAnds)
214 : Mask(APInt::getZero(BitWidth)), MatchAndChain(MatchAnds) {}
215 };
216
217 /// This is a recursive helper for foldAnyOrAllBitsSet() that walks through a
218 /// chain of 'and' or 'or' instructions looking for shift ops of a common source
219 /// value. Examples:
220 /// or (or (or X, (X >> 3)), (X >> 5)), (X >> 8)
221 /// returns { X, 0x129 }
222 /// and (and (X >> 1), 1), (X >> 4)
223 /// returns { X, 0x12 }
matchAndOrChain(Value * V,MaskOps & MOps)224 static bool matchAndOrChain(Value *V, MaskOps &MOps) {
225 Value *Op0, *Op1;
226 if (MOps.MatchAndChain) {
227 // Recurse through a chain of 'and' operands. This requires an extra check
228 // vs. the 'or' matcher: we must find an "and X, 1" instruction somewhere
229 // in the chain to know that all of the high bits are cleared.
230 if (match(V, m_And(m_Value(Op0), m_One()))) {
231 MOps.FoundAnd1 = true;
232 return matchAndOrChain(Op0, MOps);
233 }
234 if (match(V, m_And(m_Value(Op0), m_Value(Op1))))
235 return matchAndOrChain(Op0, MOps) && matchAndOrChain(Op1, MOps);
236 } else {
237 // Recurse through a chain of 'or' operands.
238 if (match(V, m_Or(m_Value(Op0), m_Value(Op1))))
239 return matchAndOrChain(Op0, MOps) && matchAndOrChain(Op1, MOps);
240 }
241
242 // We need a shift-right or a bare value representing a compare of bit 0 of
243 // the original source operand.
244 Value *Candidate;
245 const APInt *BitIndex = nullptr;
246 if (!match(V, m_LShr(m_Value(Candidate), m_APInt(BitIndex))))
247 Candidate = V;
248
249 // Initialize result source operand.
250 if (!MOps.Root)
251 MOps.Root = Candidate;
252
253 // The shift constant is out-of-range? This code hasn't been simplified.
254 if (BitIndex && BitIndex->uge(MOps.Mask.getBitWidth()))
255 return false;
256
257 // Fill in the mask bit derived from the shift constant.
258 MOps.Mask.setBit(BitIndex ? BitIndex->getZExtValue() : 0);
259 return MOps.Root == Candidate;
260 }
261
262 /// Match patterns that correspond to "any-bits-set" and "all-bits-set".
263 /// These will include a chain of 'or' or 'and'-shifted bits from a
264 /// common source value:
265 /// and (or (lshr X, C), ...), 1 --> (X & CMask) != 0
266 /// and (and (lshr X, C), ...), 1 --> (X & CMask) == CMask
267 /// Note: "any-bits-clear" and "all-bits-clear" are variations of these patterns
268 /// that differ only with a final 'not' of the result. We expect that final
269 /// 'not' to be folded with the compare that we create here (invert predicate).
foldAnyOrAllBitsSet(Instruction & I)270 static bool foldAnyOrAllBitsSet(Instruction &I) {
271 // The 'any-bits-set' ('or' chain) pattern is simpler to match because the
272 // final "and X, 1" instruction must be the final op in the sequence.
273 bool MatchAllBitsSet;
274 if (match(&I, m_c_And(m_OneUse(m_And(m_Value(), m_Value())), m_Value())))
275 MatchAllBitsSet = true;
276 else if (match(&I, m_And(m_OneUse(m_Or(m_Value(), m_Value())), m_One())))
277 MatchAllBitsSet = false;
278 else
279 return false;
280
281 MaskOps MOps(I.getType()->getScalarSizeInBits(), MatchAllBitsSet);
282 if (MatchAllBitsSet) {
283 if (!matchAndOrChain(cast<BinaryOperator>(&I), MOps) || !MOps.FoundAnd1)
284 return false;
285 } else {
286 if (!matchAndOrChain(cast<BinaryOperator>(&I)->getOperand(0), MOps))
287 return false;
288 }
289
290 // The pattern was found. Create a masked compare that replaces all of the
291 // shift and logic ops.
292 IRBuilder<> Builder(&I);
293 Constant *Mask = ConstantInt::get(I.getType(), MOps.Mask);
294 Value *And = Builder.CreateAnd(MOps.Root, Mask);
295 Value *Cmp = MatchAllBitsSet ? Builder.CreateICmpEQ(And, Mask)
296 : Builder.CreateIsNotNull(And);
297 Value *Zext = Builder.CreateZExt(Cmp, I.getType());
298 I.replaceAllUsesWith(Zext);
299 ++NumAnyOrAllBitsSet;
300 return true;
301 }
302
303 // Try to recognize below function as popcount intrinsic.
304 // This is the "best" algorithm from
305 // http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
306 // Also used in TargetLowering::expandCTPOP().
307 //
308 // int popcount(unsigned int i) {
309 // i = i - ((i >> 1) & 0x55555555);
310 // i = (i & 0x33333333) + ((i >> 2) & 0x33333333);
311 // i = ((i + (i >> 4)) & 0x0F0F0F0F);
312 // return (i * 0x01010101) >> 24;
313 // }
tryToRecognizePopCount(Instruction & I)314 static bool tryToRecognizePopCount(Instruction &I) {
315 if (I.getOpcode() != Instruction::LShr)
316 return false;
317
318 Type *Ty = I.getType();
319 if (!Ty->isIntOrIntVectorTy())
320 return false;
321
322 unsigned Len = Ty->getScalarSizeInBits();
323 // FIXME: fix Len == 8 and other irregular type lengths.
324 if (!(Len <= 128 && Len > 8 && Len % 8 == 0))
325 return false;
326
327 APInt Mask55 = APInt::getSplat(Len, APInt(8, 0x55));
328 APInt Mask33 = APInt::getSplat(Len, APInt(8, 0x33));
329 APInt Mask0F = APInt::getSplat(Len, APInt(8, 0x0F));
330 APInt Mask01 = APInt::getSplat(Len, APInt(8, 0x01));
331 APInt MaskShift = APInt(Len, Len - 8);
332
333 Value *Op0 = I.getOperand(0);
334 Value *Op1 = I.getOperand(1);
335 Value *MulOp0;
336 // Matching "(i * 0x01010101...) >> 24".
337 if ((match(Op0, m_Mul(m_Value(MulOp0), m_SpecificInt(Mask01)))) &&
338 match(Op1, m_SpecificInt(MaskShift))) {
339 Value *ShiftOp0;
340 // Matching "((i + (i >> 4)) & 0x0F0F0F0F...)".
341 if (match(MulOp0, m_And(m_c_Add(m_LShr(m_Value(ShiftOp0), m_SpecificInt(4)),
342 m_Deferred(ShiftOp0)),
343 m_SpecificInt(Mask0F)))) {
344 Value *AndOp0;
345 // Matching "(i & 0x33333333...) + ((i >> 2) & 0x33333333...)".
346 if (match(ShiftOp0,
347 m_c_Add(m_And(m_Value(AndOp0), m_SpecificInt(Mask33)),
348 m_And(m_LShr(m_Deferred(AndOp0), m_SpecificInt(2)),
349 m_SpecificInt(Mask33))))) {
350 Value *Root, *SubOp1;
351 // Matching "i - ((i >> 1) & 0x55555555...)".
352 if (match(AndOp0, m_Sub(m_Value(Root), m_Value(SubOp1))) &&
353 match(SubOp1, m_And(m_LShr(m_Specific(Root), m_SpecificInt(1)),
354 m_SpecificInt(Mask55)))) {
355 LLVM_DEBUG(dbgs() << "Recognized popcount intrinsic\n");
356 IRBuilder<> Builder(&I);
357 Function *Func = Intrinsic::getDeclaration(
358 I.getModule(), Intrinsic::ctpop, I.getType());
359 I.replaceAllUsesWith(Builder.CreateCall(Func, {Root}));
360 ++NumPopCountRecognized;
361 return true;
362 }
363 }
364 }
365 }
366
367 return false;
368 }
369
370 /// Fold smin(smax(fptosi(x), C1), C2) to llvm.fptosi.sat(x), providing C1 and
371 /// C2 saturate the value of the fp conversion. The transform is not reversable
372 /// as the fptosi.sat is more defined than the input - all values produce a
373 /// valid value for the fptosi.sat, where as some produce poison for original
374 /// that were out of range of the integer conversion. The reversed pattern may
375 /// use fmax and fmin instead. As we cannot directly reverse the transform, and
376 /// it is not always profitable, we make it conditional on the cost being
377 /// reported as lower by TTI.
tryToFPToSat(Instruction & I,TargetTransformInfo & TTI)378 static bool tryToFPToSat(Instruction &I, TargetTransformInfo &TTI) {
379 // Look for min(max(fptosi, converting to fptosi_sat.
380 Value *In;
381 const APInt *MinC, *MaxC;
382 if (!match(&I, m_SMax(m_OneUse(m_SMin(m_OneUse(m_FPToSI(m_Value(In))),
383 m_APInt(MinC))),
384 m_APInt(MaxC))) &&
385 !match(&I, m_SMin(m_OneUse(m_SMax(m_OneUse(m_FPToSI(m_Value(In))),
386 m_APInt(MaxC))),
387 m_APInt(MinC))))
388 return false;
389
390 // Check that the constants clamp a saturate.
391 if (!(*MinC + 1).isPowerOf2() || -*MaxC != *MinC + 1)
392 return false;
393
394 Type *IntTy = I.getType();
395 Type *FpTy = In->getType();
396 Type *SatTy =
397 IntegerType::get(IntTy->getContext(), (*MinC + 1).exactLogBase2() + 1);
398 if (auto *VecTy = dyn_cast<VectorType>(IntTy))
399 SatTy = VectorType::get(SatTy, VecTy->getElementCount());
400
401 // Get the cost of the intrinsic, and check that against the cost of
402 // fptosi+smin+smax
403 InstructionCost SatCost = TTI.getIntrinsicInstrCost(
404 IntrinsicCostAttributes(Intrinsic::fptosi_sat, SatTy, {In}, {FpTy}),
405 TTI::TCK_RecipThroughput);
406 SatCost += TTI.getCastInstrCost(Instruction::SExt, SatTy, IntTy,
407 TTI::CastContextHint::None,
408 TTI::TCK_RecipThroughput);
409
410 InstructionCost MinMaxCost = TTI.getCastInstrCost(
411 Instruction::FPToSI, IntTy, FpTy, TTI::CastContextHint::None,
412 TTI::TCK_RecipThroughput);
413 MinMaxCost += TTI.getIntrinsicInstrCost(
414 IntrinsicCostAttributes(Intrinsic::smin, IntTy, {IntTy}),
415 TTI::TCK_RecipThroughput);
416 MinMaxCost += TTI.getIntrinsicInstrCost(
417 IntrinsicCostAttributes(Intrinsic::smax, IntTy, {IntTy}),
418 TTI::TCK_RecipThroughput);
419
420 if (SatCost >= MinMaxCost)
421 return false;
422
423 IRBuilder<> Builder(&I);
424 Function *Fn = Intrinsic::getDeclaration(I.getModule(), Intrinsic::fptosi_sat,
425 {SatTy, FpTy});
426 Value *Sat = Builder.CreateCall(Fn, In);
427 I.replaceAllUsesWith(Builder.CreateSExt(Sat, IntTy));
428 return true;
429 }
430
431 /// Try to replace a mathlib call to sqrt with the LLVM intrinsic. This avoids
432 /// pessimistic codegen that has to account for setting errno and can enable
433 /// vectorization.
434 static bool
foldSqrt(Instruction & I,TargetTransformInfo & TTI,TargetLibraryInfo & TLI)435 foldSqrt(Instruction &I, TargetTransformInfo &TTI, TargetLibraryInfo &TLI) {
436 // Match a call to sqrt mathlib function.
437 auto *Call = dyn_cast<CallInst>(&I);
438 if (!Call)
439 return false;
440
441 Module *M = Call->getModule();
442 LibFunc Func;
443 if (!TLI.getLibFunc(*Call, Func) || !isLibFuncEmittable(M, &TLI, Func))
444 return false;
445
446 if (Func != LibFunc_sqrt && Func != LibFunc_sqrtf && Func != LibFunc_sqrtl)
447 return false;
448
449 // If (1) this is a sqrt libcall, (2) we can assume that NAN is not created,
450 // and (3) we would not end up lowering to a libcall anyway (which could
451 // change the value of errno), then:
452 // (1) the operand arg must not be less than -0.0.
453 // (2) errno won't be set.
454 // (3) it is safe to convert this to an intrinsic call.
455 // TODO: Check if the arg is known non-negative.
456 Type *Ty = Call->getType();
457 if (TTI.haveFastSqrt(Ty) && Call->hasNoNaNs()) {
458 IRBuilder<> Builder(&I);
459 IRBuilderBase::FastMathFlagGuard Guard(Builder);
460 Builder.setFastMathFlags(Call->getFastMathFlags());
461
462 Function *Sqrt = Intrinsic::getDeclaration(M, Intrinsic::sqrt, Ty);
463 Value *NewSqrt = Builder.CreateCall(Sqrt, Call->getArgOperand(0), "sqrt");
464 I.replaceAllUsesWith(NewSqrt);
465
466 // Explicitly erase the old call because a call with side effects is not
467 // trivially dead.
468 I.eraseFromParent();
469 return true;
470 }
471
472 return false;
473 }
474
475 /// This is the entry point for folds that could be implemented in regular
476 /// InstCombine, but they are separated because they are not expected to
477 /// occur frequently and/or have more than a constant-length pattern match.
foldUnusualPatterns(Function & F,DominatorTree & DT,TargetTransformInfo & TTI,TargetLibraryInfo & TLI)478 static bool foldUnusualPatterns(Function &F, DominatorTree &DT,
479 TargetTransformInfo &TTI,
480 TargetLibraryInfo &TLI) {
481 bool MadeChange = false;
482 for (BasicBlock &BB : F) {
483 // Ignore unreachable basic blocks.
484 if (!DT.isReachableFromEntry(&BB))
485 continue;
486
487 // Walk the block backwards for efficiency. We're matching a chain of
488 // use->defs, so we're more likely to succeed by starting from the bottom.
489 // Also, we want to avoid matching partial patterns.
490 // TODO: It would be more efficient if we removed dead instructions
491 // iteratively in this loop rather than waiting until the end.
492 for (Instruction &I : make_early_inc_range(llvm::reverse(BB))) {
493 MadeChange |= foldAnyOrAllBitsSet(I);
494 MadeChange |= foldGuardedFunnelShift(I, DT);
495 MadeChange |= tryToRecognizePopCount(I);
496 MadeChange |= tryToFPToSat(I, TTI);
497 MadeChange |= foldSqrt(I, TTI, TLI);
498 }
499 }
500
501 // We're done with transforms, so remove dead instructions.
502 if (MadeChange)
503 for (BasicBlock &BB : F)
504 SimplifyInstructionsInBlock(&BB);
505
506 return MadeChange;
507 }
508
509 /// This is the entry point for all transforms. Pass manager differences are
510 /// handled in the callers of this function.
runImpl(Function & F,AssumptionCache & AC,TargetTransformInfo & TTI,TargetLibraryInfo & TLI,DominatorTree & DT)511 static bool runImpl(Function &F, AssumptionCache &AC, TargetTransformInfo &TTI,
512 TargetLibraryInfo &TLI, DominatorTree &DT) {
513 bool MadeChange = false;
514 const DataLayout &DL = F.getParent()->getDataLayout();
515 TruncInstCombine TIC(AC, TLI, DL, DT);
516 MadeChange |= TIC.run(F);
517 MadeChange |= foldUnusualPatterns(F, DT, TTI, TLI);
518 return MadeChange;
519 }
520
getAnalysisUsage(AnalysisUsage & AU) const521 void AggressiveInstCombinerLegacyPass::getAnalysisUsage(
522 AnalysisUsage &AU) const {
523 AU.setPreservesCFG();
524 AU.addRequired<AssumptionCacheTracker>();
525 AU.addRequired<DominatorTreeWrapperPass>();
526 AU.addRequired<TargetLibraryInfoWrapperPass>();
527 AU.addRequired<TargetTransformInfoWrapperPass>();
528 AU.addPreserved<AAResultsWrapperPass>();
529 AU.addPreserved<BasicAAWrapperPass>();
530 AU.addPreserved<DominatorTreeWrapperPass>();
531 AU.addPreserved<GlobalsAAWrapperPass>();
532 }
533
runOnFunction(Function & F)534 bool AggressiveInstCombinerLegacyPass::runOnFunction(Function &F) {
535 auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
536 auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
537 auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
538 auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
539 return runImpl(F, AC, TTI, TLI, DT);
540 }
541
run(Function & F,FunctionAnalysisManager & AM)542 PreservedAnalyses AggressiveInstCombinePass::run(Function &F,
543 FunctionAnalysisManager &AM) {
544 auto &AC = AM.getResult<AssumptionAnalysis>(F);
545 auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
546 auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
547 auto &TTI = AM.getResult<TargetIRAnalysis>(F);
548 if (!runImpl(F, AC, TTI, TLI, DT)) {
549 // No changes, all analyses are preserved.
550 return PreservedAnalyses::all();
551 }
552 // Mark all the analyses that instcombine updates as preserved.
553 PreservedAnalyses PA;
554 PA.preserveSet<CFGAnalyses>();
555 return PA;
556 }
557
558 char AggressiveInstCombinerLegacyPass::ID = 0;
559 INITIALIZE_PASS_BEGIN(AggressiveInstCombinerLegacyPass,
560 "aggressive-instcombine",
561 "Combine pattern based expressions", false, false)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)562 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
563 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
564 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
565 INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
566 INITIALIZE_PASS_END(AggressiveInstCombinerLegacyPass, "aggressive-instcombine",
567 "Combine pattern based expressions", false, false)
568
569 // Initialization Routines
570 void llvm::initializeAggressiveInstCombine(PassRegistry &Registry) {
571 initializeAggressiveInstCombinerLegacyPassPass(Registry);
572 }
573
LLVMInitializeAggressiveInstCombiner(LLVMPassRegistryRef R)574 void LLVMInitializeAggressiveInstCombiner(LLVMPassRegistryRef R) {
575 initializeAggressiveInstCombinerLegacyPassPass(*unwrap(R));
576 }
577
createAggressiveInstCombinerPass()578 FunctionPass *llvm::createAggressiveInstCombinerPass() {
579 return new AggressiveInstCombinerLegacyPass();
580 }
581
LLVMAddAggressiveInstCombinerPass(LLVMPassManagerRef PM)582 void LLVMAddAggressiveInstCombinerPass(LLVMPassManagerRef PM) {
583 unwrap(PM)->add(createAggressiveInstCombinerPass());
584 }
585