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[X86] Add a one use check to the combineStore code that handles v16i16->v16i8 truncate+store by extending to v16i32 and then emitting a v16i32->v16i8 truncstore. 

This prevent us from emitting a separate truncate and a truncating
store instruction.

llvm-svn: 369200
This commit is contained in:
Craig Topper 2019-08-17 22:46:15 +00:00
parent a8dad5c79b
commit 31f829f0cd
2 changed files with 21 additions and 1 deletions
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2
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -39581,7 +39581,7 @@ static SDValue combineStore(SDNode *N, SelectionDAG &DAG,
St->getValue().getOpcode() == ISD::TRUNCATE &&
St->getValue().getOperand(0).getValueType() == MVT::v16i16 &&
TLI.isTruncStoreLegal(MVT::v16i32, MVT::v16i8) &&
!DCI.isBeforeLegalizeOps()) {
St->getValue().hasOneUse() && !DCI.isBeforeLegalizeOps()) {
SDValue Ext = DAG.getNode(ISD::ANY_EXTEND, dl, MVT::v16i32, St->getValue());
return DAG.getTruncStore(St->getChain(), dl, Ext, St->getBasePtr(),
MVT::v16i8, St->getMemOperand());

20
llvm/test/CodeGen/X86/avx512-trunc.ll
View File

@ -514,6 +514,26 @@ define void @trunc_wb_256_mem(<16 x i16> %i, <16 x i8>* %res) #0 {
ret void
}
define <16 x i8> @trunc_wb_256_mem_and_ret(<16 x i16> %i, <16 x i8>* %res) #0 {
; KNL-LABEL: trunc_wb_256_mem_and_ret:
; KNL: ## %bb.0:
; KNL-NEXT: vpmovzxwd {{.*#+}} zmm0 = ymm0[0],zero,ymm0[1],zero,ymm0[2],zero,ymm0[3],zero,ymm0[4],zero,ymm0[5],zero,ymm0[6],zero,ymm0[7],zero,ymm0[8],zero,ymm0[9],zero,ymm0[10],zero,ymm0[11],zero,ymm0[12],zero,ymm0[13],zero,ymm0[14],zero,ymm0[15],zero
; KNL-NEXT: vpmovdb %zmm0, %xmm0
; KNL-NEXT: vmovdqa %xmm0, (%rdi)
; KNL-NEXT: vzeroupper
; KNL-NEXT: retq
;
; SKX-LABEL: trunc_wb_256_mem_and_ret:
; SKX: ## %bb.0:
; SKX-NEXT: vpmovwb %ymm0, %xmm0
; SKX-NEXT: vmovdqa %xmm0, (%rdi)
; SKX-NEXT: vzeroupper
; SKX-NEXT: retq
%x = trunc <16 x i16> %i to <16 x i8>
store <16 x i8> %x, <16 x i8>* %res
ret <16 x i8> %x
}
define <8 x i8> @trunc_wb_128(<8 x i16> %i) #0 {
; ALL-LABEL: trunc_wb_128:
; ALL: ## %bb.0: