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[ConstraintElim] Remove const op restriction from tightenBoundUsingNe. (#213440)

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Remove the constant operand restriction for the bounds tightening logic
added in https://github.com/llvm/llvm-project/pull/213049.

The condition is not needed for correctness, and there are a number of
cases in practice where results can be improved:
https://github.com/dtcxzyw/llvm-opt-benchmark-nightly/pull/839


Compile-time impact in the noise

https://llvm-compile-time-tracker.com/compare.php?from=60f965b1f62c0c77bcdb2997ea9bb6603aa0d002&to=1f7190605cc3a13cd992eaad3053b599cd5e4ed0&stat=instructions:u

PR: https://github.com/llvm/llvm-project/pull/213440
This commit is contained in:
Florian Hahn 2026-08-01 17:01:45 +02:00 committed by GitHub
parent efe31d6dfe
commit 78909083d7
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2 changed files with 2 additions and 3 deletions
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2
llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
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@ -1793,7 +1793,7 @@ void ConstraintInfo::addFact(CmpInst::Predicate Pred, Value *A, Value *B,
void ConstraintInfo::tightenBoundUsingNe(
Value *A, Value *B, unsigned NumIn, unsigned NumOut,
SmallVectorImpl<StackEntry> &DFSInStack) {
if (!isa<ConstantInt>(B) || !A->getType()->isIntegerTy())
if (!A->getType()->isIntegerTy())
return;
for (bool IsSigned : {false, true}) {

3
llvm/test/Transforms/ConstraintElimination/ne-tightening.ll
View file

@ -242,8 +242,7 @@ define i1 @neg_ne_non_constant(i64 %n, i64 %m) {
; CHECK-NEXT: call void @llvm.assume(i1 [[A]])
; CHECK-NEXT: [[B:%.*]] = icmp ne i64 [[N]], [[M]]
; CHECK-NEXT: call void @llvm.assume(i1 [[B]])
; CHECK-NEXT: [[C:%.*]] = icmp sgt i64 [[N]], [[M]]
; CHECK-NEXT: ret i1 [[C]]
; CHECK-NEXT: ret i1 true
;
%a = icmp sge i64 %n, %m
call void @llvm.assume(i1 %a)