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[VectorCombine] foldBitcastShuffle - peek through any residual bitcasts before creating a new bitcast on top #86119

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Merged
merged 1 commit into from
Apr 2, 2024
Merged

[VectorCombine] foldBitcastShuffle - peek through any residual bitcasts before creating a new bitcast on top #86119

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12 changes: 10 additions & 2 deletions llvm/lib/Transforms/Vectorize/VectorCombine.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -135,6 +135,14 @@ class VectorCombine {
};
} // namespace

/// Return the source operand of a potentially bitcasted value. If there is no
/// bitcast, return the input value itself.
static Value *peekThroughBitcasts(Value *V) {
while (auto *BitCast = dyn_cast<BitCastInst>(V))
V = BitCast->getOperand(0);
return V;
}

static bool canWidenLoad(LoadInst *Load, const TargetTransformInfo &TTI) {
// Do not widen load if atomic/volatile or under asan/hwasan/memtag/tsan.
// The widened load may load data from dirty regions or create data races
Expand Down Expand Up @@ -751,8 +759,8 @@ bool VectorCombine::foldBitcastShuffle(Instruction &I) {

// bitcast (shuf V0, V1, MaskC) --> shuf (bitcast V0), (bitcast V1), MaskC'
++NumShufOfBitcast;
Value *CastV0 = Builder.CreateBitCast(V0, NewShuffleTy);
Value *CastV1 = Builder.CreateBitCast(V1, NewShuffleTy);
Value *CastV0 = Builder.CreateBitCast(peekThroughBitcasts(V0), NewShuffleTy);
Value *CastV1 = Builder.CreateBitCast(peekThroughBitcasts(V1), NewShuffleTy);
Value *Shuf = Builder.CreateShuffleVector(CastV0, CastV1, NewMask);
replaceValue(I, *Shuf);
return true;
Expand Down
6 changes: 2 additions & 4 deletions llvm/test/Transforms/VectorCombine/X86/shuffle-inseltpoison.ll
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Expand Up @@ -133,8 +133,7 @@ define <2 x i64> @PR35454_1(<2 x i64> %v) {
; SSE-NEXT: ret <2 x i64> [[BC3]]
;
; AVX-LABEL: @PR35454_1(
; AVX-NEXT: [[BC:%.*]] = bitcast <2 x i64> [[V:%.*]] to <4 x i32>
; AVX-NEXT: [[TMP1:%.*]] = bitcast <4 x i32> [[BC]] to <16 x i8>
; AVX-NEXT: [[TMP1:%.*]] = bitcast <2 x i64> [[V:%.*]] to <16 x i8>
; AVX-NEXT: [[BC1:%.*]] = shufflevector <16 x i8> [[TMP1]], <16 x i8> poison, <16 x i32> <i32 12, i32 13, i32 14, i32 15, i32 8, i32 9, i32 10, i32 11, i32 4, i32 5, i32 6, i32 7, i32 0, i32 1, i32 2, i32 3>
; AVX-NEXT: [[ADD:%.*]] = shl <16 x i8> [[BC1]], <i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1>
; AVX-NEXT: [[BC2:%.*]] = bitcast <16 x i8> [[ADD]] to <4 x i32>
Expand Down Expand Up @@ -164,8 +163,7 @@ define <2 x i64> @PR35454_2(<2 x i64> %v) {
; SSE-NEXT: ret <2 x i64> [[BC3]]
;
; AVX-LABEL: @PR35454_2(
; AVX-NEXT: [[BC:%.*]] = bitcast <2 x i64> [[V:%.*]] to <4 x i32>
; AVX-NEXT: [[TMP1:%.*]] = bitcast <4 x i32> [[BC]] to <8 x i16>
; AVX-NEXT: [[TMP1:%.*]] = bitcast <2 x i64> [[V:%.*]] to <8 x i16>
; AVX-NEXT: [[BC1:%.*]] = shufflevector <8 x i16> [[TMP1]], <8 x i16> poison, <8 x i32> <i32 6, i32 7, i32 4, i32 5, i32 2, i32 3, i32 0, i32 1>
; AVX-NEXT: [[ADD:%.*]] = shl <8 x i16> [[BC1]], <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
; AVX-NEXT: [[BC2:%.*]] = bitcast <8 x i16> [[ADD]] to <4 x i32>
Expand Down
6 changes: 2 additions & 4 deletions llvm/test/Transforms/VectorCombine/X86/shuffle.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -133,8 +133,7 @@ define <2 x i64> @PR35454_1(<2 x i64> %v) {
; SSE-NEXT: ret <2 x i64> [[BC3]]
;
; AVX-LABEL: @PR35454_1(
; AVX-NEXT: [[BC:%.*]] = bitcast <2 x i64> [[V:%.*]] to <4 x i32>
; AVX-NEXT: [[TMP1:%.*]] = bitcast <4 x i32> [[BC]] to <16 x i8>
; AVX-NEXT: [[TMP1:%.*]] = bitcast <2 x i64> [[V:%.*]] to <16 x i8>
; AVX-NEXT: [[BC1:%.*]] = shufflevector <16 x i8> [[TMP1]], <16 x i8> poison, <16 x i32> <i32 12, i32 13, i32 14, i32 15, i32 8, i32 9, i32 10, i32 11, i32 4, i32 5, i32 6, i32 7, i32 0, i32 1, i32 2, i32 3>
; AVX-NEXT: [[ADD:%.*]] = shl <16 x i8> [[BC1]], <i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1>
; AVX-NEXT: [[BC2:%.*]] = bitcast <16 x i8> [[ADD]] to <4 x i32>
Expand Down Expand Up @@ -164,8 +163,7 @@ define <2 x i64> @PR35454_2(<2 x i64> %v) {
; SSE-NEXT: ret <2 x i64> [[BC3]]
;
; AVX-LABEL: @PR35454_2(
; AVX-NEXT: [[BC:%.*]] = bitcast <2 x i64> [[V:%.*]] to <4 x i32>
; AVX-NEXT: [[TMP1:%.*]] = bitcast <4 x i32> [[BC]] to <8 x i16>
; AVX-NEXT: [[TMP1:%.*]] = bitcast <2 x i64> [[V:%.*]] to <8 x i16>
; AVX-NEXT: [[BC1:%.*]] = shufflevector <8 x i16> [[TMP1]], <8 x i16> poison, <8 x i32> <i32 6, i32 7, i32 4, i32 5, i32 2, i32 3, i32 0, i32 1>
; AVX-NEXT: [[ADD:%.*]] = shl <8 x i16> [[BC1]], <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
; AVX-NEXT: [[BC2:%.*]] = bitcast <8 x i16> [[ADD]] to <4 x i32>
Expand Down