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[DAGCombiner] When folding (insert_subvector undef, (bitcast (extract_subvector N1, Idx)), Idx) -> (bitcast N1) make sure that N1 has the same total size as the original output

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We were only checking the element count, but not the total width. This could cause illegal bitcasts to be created if for example the output was 512-bits, but N1 is 256 bits, and the extraction size was 128-bits.

Fixes PR36199

Differential Revision: https://reviews.llvm.org/D42809

llvm-svn: 324002
This commit is contained in:
Craig Topper 2018-02-01 20:48:50 +00:00
parent ae95e7a615
commit 2a3ca1333b
2 changed files with 25 additions and 1 deletions
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4
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -16465,7 +16465,9 @@ SDValue DAGCombiner::visitINSERT_SUBVECTOR(SDNode *N) {
N1.getOperand(0).getOpcode() == ISD::EXTRACT_SUBVECTOR &&
N1.getOperand(0).getOperand(1) == N2 &&
N1.getOperand(0).getOperand(0).getValueType().getVectorNumElements() ==
VT.getVectorNumElements()) {
VT.getVectorNumElements() &&
N1.getOperand(0).getOperand(0).getValueType().getSizeInBits() ==
VT.getSizeInBits()) {
return DAG.getBitcast(VT, N1.getOperand(0).getOperand(0));
}

22
test/CodeGen/X86/pr36199.ll Normal file
View File

@ -0,0 +1,22 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=skylake-avx512 | FileCheck %s
define void @foo() unnamed_addr #0 {
; CHECK-LABEL: foo:
; CHECK: # %bb.0:
; CHECK-NEXT: vaddps %zmm0, %zmm0, %zmm0
; CHECK-NEXT: vinsertf128 $1, %xmm0, %ymm0, %ymm0
; CHECK-NEXT: vinsertf64x4 $1, %ymm0, %zmm0, %zmm0
; CHECK-NEXT: vmovups %zmm0, (%rax)
; CHECK-NEXT: vzeroupper
; CHECK-NEXT: retq
%1 = fadd <16 x float> undef, undef
%bc256 = bitcast <16 x float> %1 to <4 x i128>
%2 = extractelement <4 x i128> %bc256, i32 0
%3 = bitcast i128 %2 to <4 x float>
%4 = shufflevector <4 x float> %3, <4 x float> undef, <16 x i32> <i32 0, i32
1, i32 2, i32 3, i32 0, i32 1, i32 2, i32 3, i32 0, i32 1, i32 2, i32 3, i32 0,
i32 1, i32 2, i32 3>
store <16 x float> %4, <16 x float>* undef, align 4
ret void
}