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[BasicAA] Treat different VScale intrinsics as the same value. #81152

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Merged
merged 1 commit into from
Feb 12, 2024
+12 −4
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[BasicAA] Treat different VScale intrinsics as the same value. #81152

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12 changes: 10 additions & 2 deletions llvm/lib/Analysis/BasicAliasAnalysis.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -188,6 +188,12 @@ static bool isObjectSize(const Value *V, TypeSize Size, const DataLayout &DL,
return ObjectSize && *ObjectSize == Size;
}

/// Return true if both V1 and V2 are VScale
static bool areBothVScale(const Value *V1, const Value *V2) {
return PatternMatch::match(V1, PatternMatch::m_VScale()) &&
PatternMatch::match(V2, PatternMatch::m_VScale());
}

//===----------------------------------------------------------------------===//
// CaptureInfo implementations
//===----------------------------------------------------------------------===//
Expand Down Expand Up @@ -679,7 +685,8 @@ BasicAAResult::DecomposeGEPExpression(const Value *V, const DataLayout &DL,
// A[x][x] -> x*16 + x*4 -> x*20
// This also ensures that 'x' only appears in the index list once.
for (unsigned i = 0, e = Decomposed.VarIndices.size(); i != e; ++i) {
if (Decomposed.VarIndices[i].Val.V == LE.Val.V &&
if ((Decomposed.VarIndices[i].Val.V == LE.Val.V ||
areBothVScale(Decomposed.VarIndices[i].Val.V, LE.Val.V)) &&
Decomposed.VarIndices[i].Val.hasSameCastsAs(LE.Val)) {
Scale += Decomposed.VarIndices[i].Scale;
LE.IsNSW = false; // We cannot guarantee nsw for the merge.
Expand Down Expand Up @@ -1792,7 +1799,8 @@ void BasicAAResult::subtractDecomposedGEPs(DecomposedGEP &DestGEP,
bool Found = false;
for (auto I : enumerate(DestGEP.VarIndices)) {
VariableGEPIndex &Dest = I.value();
if (!isValueEqualInPotentialCycles(Dest.Val.V, Src.Val.V, AAQI) ||
if ((!isValueEqualInPotentialCycles(Dest.Val.V, Src.Val.V, AAQI) &&
!areBothVScale(Dest.Val.V, Src.Val.V)) ||
!Dest.Val.hasSameCastsAs(Src.Val))
continue;

Expand Down
4 changes: 2 additions & 2 deletions llvm/test/Analysis/BasicAA/vscale.ll
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Expand Up @@ -488,9 +488,9 @@ define void @onevscale(ptr %p) vscale_range(1,16) {
}

; CHECK-LABEL: twovscales
; CHECK-DAG: MayAlias: <vscale x 4 x i32>* %vp161, <vscale x 4 x i32>* %vp162
; CHECK-DAG: MustAlias: <vscale x 4 x i32>* %vp161, <vscale x 4 x i32>* %vp162
; CHECK-DAG: NoAlias: <vscale x 4 x i32>* %vp161, <vscale x 4 x i32>* %vp161b
; CHECK-DAG: MayAlias: <vscale x 4 x i32>* %vp161b, <vscale x 4 x i32>* %vp162
; CHECK-DAG: NoAlias: <vscale x 4 x i32>* %vp161b, <vscale x 4 x i32>* %vp162
define void @twovscales(ptr %p) vscale_range(1,16) {
%v1 = call i64 @llvm.vscale.i64()
%v2 = call i64 @llvm.vscale.i64()
Expand Down