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[ConstantFolding] Fold deinterleave2 of any splat vector not just zeroinitializer #144144

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Merged
merged 1 commit into from
Jun 14, 2025
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[ConstantFolding] Fold deinterleave2 of any splat vector not just zeroinitializer #144144

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43 changes: 21 additions & 22 deletions llvm/lib/Analysis/ConstantFolding.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3990,31 +3990,30 @@ ConstantFoldStructCall(StringRef Name, Intrinsic::ID IntrinsicID,
return ConstantStruct::get(StTy, SinResult, CosResult);
}
case Intrinsic::vector_deinterleave2: {
auto *Vec = dyn_cast<Constant>(Operands[0]);
if (!Vec)
return nullptr;

auto *Vec = Operands[0];
auto *VecTy = cast<VectorType>(Vec->getType());
unsigned NumElements = VecTy->getElementCount().getKnownMinValue() / 2;
if (isa<ConstantAggregateZero>(Vec)) {
auto *HalfVecTy = VectorType::getHalfElementsVectorType(VecTy);
return ConstantStruct::get(StTy, ConstantAggregateZero::get(HalfVecTy),
ConstantAggregateZero::get(HalfVecTy));

if (auto *EltC = Vec->getSplatValue()) {
ElementCount HalfEC = VecTy->getElementCount().divideCoefficientBy(2);
auto *HalfVec = ConstantVector::getSplat(HalfEC, EltC);
return ConstantStruct::get(StTy, HalfVec, HalfVec);
}
if (isa<FixedVectorType>(Vec->getType())) {
SmallVector<Constant *, 4> Res0(NumElements), Res1(NumElements);
for (unsigned I = 0; I < NumElements; ++I) {
Constant *Elt0 = Vec->getAggregateElement(2 * I);
Constant *Elt1 = Vec->getAggregateElement(2 * I + 1);
if (!Elt0 || !Elt1)
return nullptr;
Res0[I] = Elt0;
Res1[I] = Elt1;
}
return ConstantStruct::get(StTy, ConstantVector::get(Res0),
ConstantVector::get(Res1));

if (!isa<FixedVectorType>(Vec->getType()))
return nullptr;

unsigned NumElements = VecTy->getElementCount().getFixedValue() / 2;
SmallVector<Constant *, 4> Res0(NumElements), Res1(NumElements);
for (unsigned I = 0; I < NumElements; ++I) {
Constant *Elt0 = Vec->getAggregateElement(2 * I);
Constant *Elt1 = Vec->getAggregateElement(2 * I + 1);
if (!Elt0 || !Elt1)
return nullptr;
Res0[I] = Elt0;
Res1[I] = Elt1;
}
return nullptr;
return ConstantStruct::get(StTy, ConstantVector::get(Res0),
ConstantVector::get(Res1));
}
default:
// TODO: Constant folding of vector intrinsics that fall through here does
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16 changes: 16 additions & 0 deletions llvm/test/Transforms/InstSimplify/ConstProp/vector-calls.ll
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Expand Up @@ -66,3 +66,19 @@ define {<vscale x 4 x i32>, <vscale x 4 x i32>} @fold_scalable_vector_deinterlea
%1 = call {<vscale x 4 x i32>, <vscale x 4 x i32>} @llvm.vector.deinterleave2.v4i32.v8i32(<vscale x 8 x i32> zeroinitializer)
ret {<vscale x 4 x i32>, <vscale x 4 x i32>} %1
}

define {<vscale x 4 x i32>, <vscale x 4 x i32>} @fold_scalable_vector_deinterleave2_splat() {
; CHECK-LABEL: define { <vscale x 4 x i32>, <vscale x 4 x i32> } @fold_scalable_vector_deinterleave2_splat() {
; CHECK-NEXT: ret { <vscale x 4 x i32>, <vscale x 4 x i32> } { <vscale x 4 x i32> splat (i32 1), <vscale x 4 x i32> splat (i32 1) }
;
%1 = call {<vscale x 4 x i32>, <vscale x 4 x i32>} @llvm.vector.deinterleave2.v4i32.v8i32(<vscale x 8 x i32> splat (i32 1))
ret {<vscale x 4 x i32>, <vscale x 4 x i32>} %1
}

define {<vscale x 4 x float>, <vscale x 4 x float>} @fold_scalable_vector_deinterleave2_splatfp() {
; CHECK-LABEL: define { <vscale x 4 x float>, <vscale x 4 x float> } @fold_scalable_vector_deinterleave2_splatfp() {
; CHECK-NEXT: ret { <vscale x 4 x float>, <vscale x 4 x float> } { <vscale x 4 x float> splat (float 1.000000e+00), <vscale x 4 x float> splat (float 1.000000e+00) }
;
%1 = call {<vscale x 4 x float>, <vscale x 4 x float>} @llvm.vector.deinterleave2.v4f32.v8f32(<vscale x 8 x float> splat (float 1.0))
ret {<vscale x 4 x float>, <vscale x 4 x float>} %1
}
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