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[ConstraintElimination] Update Changed status in ssub simplification. 

Update tryToSimplifyOverflowMath to indicate whether the function made
any changes to the IR.
This commit is contained in:
Florian Hahn 2022-10-02 14:25:51 +01:00
parent 8193f0d1d2
commit 3fe6ddd999
No known key found for this signature in database
GPG Key ID: EEF712BB5E80EBBA
2 changed files with 15 additions and 6 deletions
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19
llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
View File

@ -670,7 +670,7 @@ void ConstraintInfo::addFact(CmpInst::Predicate Pred, Value *A, Value *B,
}
}
static void
static bool
tryToSimplifyOverflowMath(IntrinsicInst *II, ConstraintInfo &Info,
SmallVectorImpl<Instruction *> &ToRemove) {
auto DoesConditionHold = [](CmpInst::Predicate Pred, Value *A, Value *B,
@ -684,6 +684,7 @@ tryToSimplifyOverflowMath(IntrinsicInst *II, ConstraintInfo &Info,
return CSToUse.isConditionImplied(R.Coefficients);
};
bool Changed = false;
if (II->getIntrinsicID() == Intrinsic::ssub_with_overflow) {
// If A s>= B && B s>= 0, ssub.with.overflow(a, b) should not overflow and
// can be simplified to a regular sub.
@ -692,7 +693,7 @@ tryToSimplifyOverflowMath(IntrinsicInst *II, ConstraintInfo &Info,
if (!DoesConditionHold(CmpInst::ICMP_SGE, A, B, Info) ||
!DoesConditionHold(CmpInst::ICMP_SGE, B,
ConstantInt::get(A->getType(), 0), Info))
return;
return false;
IRBuilder<> Builder(II->getParent(), II->getIterator());
Value *Sub = nullptr;
@ -701,21 +702,27 @@ tryToSimplifyOverflowMath(IntrinsicInst *II, ConstraintInfo &Info,
if (!Sub)
Sub = Builder.CreateSub(A, B);
U->replaceAllUsesWith(Sub);
} else if (match(U, m_ExtractValue<1>(m_Value())))
Changed = true;
} else if (match(U, m_ExtractValue<1>(m_Value()))) {
U->replaceAllUsesWith(Builder.getFalse());
else
Changed = true;
} else
continue;
if (U->use_empty()) {
auto *I = cast<Instruction>(U);
ToRemove.push_back(I);
I->setOperand(0, PoisonValue::get(II->getType()));
Changed = true;
}
}
if (II->use_empty())
if (II->use_empty()) {
II->eraseFromParent();
Changed = true;
}
}
return Changed;
}
static bool eliminateConstraints(Function &F, DominatorTree &DT) {
@ -786,7 +793,7 @@ static bool eliminateConstraints(Function &F, DominatorTree &DT) {
if (CB.IsBlock) {
for (Instruction &I : make_early_inc_range(*CB.BB)) {
if (auto *II = dyn_cast<WithOverflowInst>(&I)) {
tryToSimplifyOverflowMath(II, Info, ToRemove);
Changed |= tryToSimplifyOverflowMath(II, Info, ToRemove);
continue;
}
auto *Cmp = dyn_cast<ICmpInst>(&I);

2
llvm/test/Transforms/ConstraintElimination/analysis-invalidation.ll
View File

@ -11,7 +11,9 @@
; CHECK-NEXT: Running analysis: TargetIRAnalysis on ssub_no_overflow_due_to_or_conds
; CHECK-NEXT: Running analysis: DominatorTreeAnalysis on ssub_no_overflow_due_to_or_conds
; CHECK-NEXT: Running pass: ConstraintEliminationPass on ssub_no_overflow_due_to_or_conds
; CHECK-NEXT: Invalidating analysis: DemandedBitsAnalysis on ssub_no_overflow_due_to_or_conds
; CHECK-NEXT: Running pass: RequireAnalysisPass
; CHECK-NEXT: Running analysis: DemandedBitsAnalysis on ssub_no_overflow_due_to_or_conds
; CHECK-NEXT: Running pass: RequireAnalysisPass
; CHECK-NEXT: Running analysis: DemandedBitsAnalysis on uge_zext