[LLVM][InstCombine] Extend masked_gather's demanded elt analysis. #151732
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Add support for other Constant types for the mask operand.
llvmbot
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llvm:instcombine
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@llvm/pr-subscribers-llvm-transforms Author: Paul Walker (paulwalker-arm) ChangesAdd support for other Constant types for the mask operand. Full diff: https://github.com/llvm/llvm-project/pull/151732.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 0e3436d12702d..c82dae7ac6e65 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -1834,14 +1834,22 @@ Value *InstCombinerImpl::SimplifyDemandedVectorElts(Value *V,
// segfaults which didn't exist in the original program.
APInt DemandedPtrs(APInt::getAllOnes(VWidth)),
DemandedPassThrough(DemandedElts);
- if (auto *CV = dyn_cast<ConstantVector>(II->getOperand(2)))
- for (unsigned i = 0; i < VWidth; i++) {
- Constant *CElt = CV->getAggregateElement(i);
- if (CElt->isNullValue())
- DemandedPtrs.clearBit(i);
- else if (CElt->isAllOnesValue())
- DemandedPassThrough.clearBit(i);
+ if (auto *CMask = dyn_cast<Constant>(II->getOperand(2))) {
+ if (CMask->isNullValue())
+ DemandedPtrs.clearAllBits();
+ else if (CMask->isAllOnesValue())
+ DemandedPassThrough.clearAllBits();
+ else if (auto *CV = dyn_cast<ConstantVector>(CMask)) {
+ for (unsigned i = 0; i < VWidth; i++) {
+ Constant *CElt = CV->getAggregateElement(i);
+ if (CElt->isNullValue())
+ DemandedPtrs.clearBit(i);
+ else if (CElt->isAllOnesValue())
+ DemandedPassThrough.clearBit(i);
+ }
}
+ }
+
if (II->getIntrinsicID() == Intrinsic::masked_gather)
simplifyAndSetOp(II, 0, DemandedPtrs, PoisonElts2);
simplifyAndSetOp(II, 3, DemandedPassThrough, PoisonElts3);
diff --git a/llvm/test/Transforms/InstCombine/masked_intrinsics.ll b/llvm/test/Transforms/InstCombine/masked_intrinsics.ll
index d9f022442a02e..8f7683419a82a 100644
--- a/llvm/test/Transforms/InstCombine/masked_intrinsics.ll
+++ b/llvm/test/Transforms/InstCombine/masked_intrinsics.ll
@@ -1,5 +1,6 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -passes=instcombine -S < %s | FileCheck %s
+; RUN: opt -passes=instcombine -use-constant-int-for-fixed-length-splat -S < %s | FileCheck %s
declare <2 x double> @llvm.masked.load.v2f64.p0(ptr %ptrs, i32, <2 x i1> %mask, <2 x double> %src0)
declare void @llvm.masked.store.v2f64.p0(<2 x double> %val, ptr %ptrs, i32, <2 x i1> %mask)
|
nikic
reviewed
Aug 1, 2025
| DemandedPtrs.clearBit(i); | ||
| else if (CElt->isAllOnesValue()) | ||
| DemandedPassThrough.clearBit(i); | ||
| if (auto *CMask = dyn_cast<Constant>(II->getOperand(2))) { |
Contributor
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I think an alternative would be to replace dyn_cast<ConstantVector> with dyn_cast<Constant>? Less efficient, but simpler.
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Works for me. Thanks.
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Add support for other Constant types for the mask operand.