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[X86][SSE] Remove INSERTPS dependencies from unreferenced operands. 

If the INSERTPS zeroes out all the referenced elements from either of the 2 input vectors (and the input is not already UNDEF), then set that input to UNDEF to reduce dependencies.

llvm-svn: 258622
This commit is contained in:
Simon Pilgrim 2016-01-23 13:37:07 +00:00
parent 0d9dd7df60
commit fd66169341
2 changed files with 45 additions and 3 deletions
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16
llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -23937,9 +23937,19 @@ static SDValue PerformTargetShuffleCombine(SDValue N, SelectionDAG &DAG,
SDValue Op1 = N.getOperand(1);
SDValue Op2 = N.getOperand(2);
unsigned InsertPSMask = cast<ConstantSDNode>(Op2)->getZExtValue();
unsigned DstIdx = (InsertPSMask >> 4) & 3;
unsigned DstIdx = (InsertPSMask >> 4) & 0x3;
unsigned ZeroMask = InsertPSMask & 0xF;
// If we zero out all elements from Op0 then we don't need to reference it.
if (((ZeroMask | (1u << DstIdx)) == 0xF) && !Op0.isUndef())
return DAG.getNode(X86ISD::INSERTPS, DL, VT, DAG.getUNDEF(VT), Op1,
DAG.getConstant(InsertPSMask, DL, MVT::i8));
// If we zero out the element from Op1 then we don't need to reference it.
if ((ZeroMask & (1u << DstIdx)) && !Op1.isUndef())
return DAG.getNode(X86ISD::INSERTPS, DL, VT, Op0, DAG.getUNDEF(VT),
DAG.getConstant(InsertPSMask, DL, MVT::i8));
// Attempt to merge insertps with an inner target shuffle node.
SmallVector<int, 8> TargetMask;
if (!setTargetShuffleZeroElements(Op0, TargetMask))
return SDValue();
@ -23979,7 +23989,7 @@ static SDValue PerformTargetShuffleCombine(SDValue N, SelectionDAG &DAG,
}
if (Updated)
return DAG.getNode(X86ISD::INSERTPS, DL, MVT::v4f32, Op0, Op1,
return DAG.getNode(X86ISD::INSERTPS, DL, VT, Op0, Op1,
DAG.getConstant(InsertPSMask, DL, MVT::i8));
return SDValue();

32
llvm/test/CodeGen/X86/insertps-combine.ll
View File

@ -98,6 +98,38 @@ define <4 x float> @shuffle_v4f32_0z6z(<4 x float> %A, <4 x float> %B) {
ret <4 x float> %vecinit4
}
define <4 x float> @insertps_undef_input0(<4 x float> %a0, <4 x float> %a1) {
; SSE-LABEL: insertps_undef_input0:
; SSE: # BB#0:
; SSE-NEXT: insertps {{.*#+}} xmm0 = zero,xmm1[0],zero,zero
; SSE-NEXT: retq
;
; AVX-LABEL: insertps_undef_input0:
; AVX: # BB#0:
; AVX-NEXT: vinsertps {{.*#+}} xmm0 = zero,xmm1[0],zero,zero
; AVX-NEXT: retq
%res0 = fadd <4 x float> %a0, <float 1.0, float 1.0, float 1.0, float 1.0>
%res1 = call <4 x float> @llvm.x86.sse41.insertps(<4 x float> %res0, <4 x float> %a1, i8 21)
%res2 = shufflevector <4 x float> %res1, <4 x float> zeroinitializer, <4 x i32> <i32 0, i32 1, i32 2, i32 7>
ret <4 x float> %res2
}
define <4 x float> @insertps_undef_input1(<4 x float> %a0, <4 x float> %a1) {
; SSE-LABEL: insertps_undef_input1:
; SSE: # BB#0:
; SSE-NEXT: insertps {{.*#+}} xmm0 = zero,zero,zero,xmm0[3]
; SSE-NEXT: retq
;
; AVX-LABEL: insertps_undef_input1:
; AVX: # BB#0:
; AVX-NEXT: vinsertps {{.*#+}} xmm0 = zero,zero,zero,xmm0[3]
; AVX-NEXT: retq
%res0 = fadd <4 x float> %a1, <float 1.0, float 1.0, float 1.0, float 1.0>
%res1 = call <4 x float> @llvm.x86.sse41.insertps(<4 x float> %a0, <4 x float> %res0, i8 21)
%res2 = shufflevector <4 x float> %res1, <4 x float> zeroinitializer, <4 x i32> <i32 0, i32 5, i32 2, i32 3>
ret <4 x float> %res2
}
define float @extract_zero_insertps_z0z7(<4 x float> %a0, <4 x float> %a1) {
; SSE-LABEL: extract_zero_insertps_z0z7:
; SSE: # BB#0: