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[InstCombine] Fix bswap(trunc(bswap(x))) -> trunc(lshr(x, c)) vector support

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Use getScalarSizeInBits not getPrimitiveSizeInBits to determine the shift value at the element level.
This commit is contained in:
Simon Pilgrim 2020-09-30 15:51:54 +01:00
parent b85de2c69c
commit 323d08e50a
2 changed files with 8 additions and 4 deletions
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4
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
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@ -828,8 +828,8 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
// bswap(trunc(bswap(x))) -> trunc(lshr(x, c))
if (match(IIOperand, m_Trunc(m_BSwap(m_Value(X))))) {
unsigned C = X->getType()->getPrimitiveSizeInBits() -
IIOperand->getType()->getPrimitiveSizeInBits();
unsigned C = X->getType()->getScalarSizeInBits() -
IIOperand->getType()->getScalarSizeInBits();
Value *CV = ConstantInt::get(X->getType(), C);
Value *V = Builder.CreateLShr(X, CV);
return new TruncInst(V, IIOperand->getType());

8
llvm/test/Transforms/InstCombine/bswap-fold.ll
View File

@ -39,7 +39,9 @@ define i16 @test7(i32 %A) {
define <2 x i16> @test7_vector(<2 x i32> %A) {
; CHECK-LABEL: @test7_vector(
; CHECK-NEXT: ret <2 x i16> undef
; CHECK-NEXT: [[TMP1:%.*]] = lshr <2 x i32> [[A:%.*]], <i32 16, i32 16>
; CHECK-NEXT: [[D:%.*]] = trunc <2 x i32> [[TMP1]] to <2 x i16>
; CHECK-NEXT: ret <2 x i16> [[D]]
;
%B = tail call <2 x i32> @llvm.bswap.v2i32(<2 x i32> %A) nounwind
%C = trunc <2 x i32> %B to <2 x i16>
@ -61,7 +63,9 @@ define i16 @test8(i64 %A) {
define <2 x i16> @test8_vector(<2 x i64> %A) {
; CHECK-LABEL: @test8_vector(
; CHECK-NEXT: ret <2 x i16> undef
; CHECK-NEXT: [[TMP1:%.*]] = lshr <2 x i64> [[A:%.*]], <i64 48, i64 48>
; CHECK-NEXT: [[D:%.*]] = trunc <2 x i64> [[TMP1]] to <2 x i16>
; CHECK-NEXT: ret <2 x i16> [[D]]
;
%B = tail call <2 x i64> @llvm.bswap.v2i64(<2 x i64> %A) nounwind
%C = trunc <2 x i64> %B to <2 x i16>