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[BasicAA] Fix Scale check in vscale aliasing. #81174

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Merged
merged 1 commit into from
Feb 9, 2024
Merged

[BasicAA] Fix Scale check in vscale aliasing. #81174

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2 changes: 1 addition & 1 deletion llvm/lib/Analysis/BasicAliasAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1187,7 +1187,7 @@ AliasResult BasicAAResult::aliasGEP(
// so noalias still holds so long as the dependency distance is at least as
// big as the typesize.
if (VLeftSize.hasValue() &&
Scale.uge(VLeftSize.getValue().getKnownMinValue()))
Scale.abs().uge(VLeftSize.getValue().getKnownMinValue()))
return AliasResult::NoAlias;
}

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11 changes: 11 additions & 0 deletions llvm/test/Analysis/BasicAA/vscale.ll
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Expand Up @@ -458,6 +458,17 @@ define void @vscale_v1v2types(ptr %p) {
ret void
}

; CHECK-LABEL: vscale_negativescale
; CHECK-DAG: MayAlias: <vscale x 4 x i32>* %p, <vscale x 4 x i32>* %vm16
define void @vscale_negativescale(ptr %p) vscale_range(1,16) {
%v = call i64 @llvm.vscale.i64()
%vm = mul nsw i64 %v, -15
%vm16 = getelementptr i8, ptr %p, i64 %vm
load <vscale x 4 x i32>, ptr %vm16
load <vscale x 4 x i32>, ptr %p
ret void
}

; CHECK-LABEL: twovscales
; CHECK-DAG: MayAlias: <vscale x 4 x i32>* %vp161, <vscale x 4 x i32>* %vp162
; CHECK-DAG: MayAlias: <vscale x 4 x i32>* %vp161, <vscale x 4 x i32>* %vp161b
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