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[DAGCombiner] Add add/sub saturation undef handling

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Match ConstantFolding.cpp:
(add_sat x, undef) -> -1
(sub_sat x, undef) -> 0

llvm-svn: 351070
This commit is contained in:
Simon Pilgrim 2019-01-14 14:16:24 +00:00
parent 7a99727c62
commit 7fc6882374
6 changed files with 27 additions and 33 deletions
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8
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -2194,6 +2194,10 @@ SDValue DAGCombiner::visitADDSAT(SDNode *N) {
return N1;
}
// fold (add_sat x, undef) -> -1
if (N0.isUndef() || N1.isUndef())
return DAG.getAllOnesConstant(DL, VT);
if (DAG.isConstantIntBuildVectorOrConstantInt(N0)) {
// canonicalize constant to RHS
if (!DAG.isConstantIntBuildVectorOrConstantInt(N1))
@ -2792,6 +2796,10 @@ SDValue DAGCombiner::visitSUBSAT(SDNode *N) {
return N0;
}
// fold (sub_sat x, undef) -> 0
if (N0.isUndef() || N1.isUndef())
return DAG.getConstant(0, DL, VT);
// TODO Constant Folding
// fold (sub_sat x, 0) -> x

6
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -5180,6 +5180,8 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
case ISD::SDIV:
case ISD::UREM:
case ISD::SREM:
case ISD::SSUBSAT:
case ISD::USUBSAT:
return getConstant(0, DL, VT); // fold op(undef, arg2) -> 0
}
}
@ -5203,8 +5205,12 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
return getUNDEF(VT); // fold op(arg1, undef) -> undef
case ISD::MUL:
case ISD::AND:
case ISD::SSUBSAT:
case ISD::USUBSAT:
return getConstant(0, DL, VT); // fold op(arg1, undef) -> 0
case ISD::OR:
case ISD::SADDSAT:
case ISD::UADDSAT:
return getAllOnesConstant(DL, VT);
}
}

18
llvm/test/CodeGen/X86/combine-add-ssat.ll
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@ -15,13 +15,7 @@ declare <8 x i16> @llvm.sadd.sat.v8i16(<8 x i16>, <8 x i16>)
define i32 @combine_undef_i32(i32 %a0) {
; CHECK-LABEL: combine_undef_i32:
; CHECK: # %bb.0:
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: movl %edi, %ecx
; CHECK-NEXT: addl %eax, %ecx
; CHECK-NEXT: setns %al
; CHECK-NEXT: addl $2147483647, %eax # imm = 0x7FFFFFFF
; CHECK-NEXT: addl %eax, %edi
; CHECK-NEXT: cmovnol %edi, %eax
; CHECK-NEXT: movl $-1, %eax
; CHECK-NEXT: retq
%res = call i32 @llvm.sadd.sat.i32(i32 %a0, i32 undef)
ret i32 %res
@ -30,12 +24,12 @@ define i32 @combine_undef_i32(i32 %a0) {
define <8 x i16> @combine_undef_v8i16(<8 x i16> %a0) {
; SSE-LABEL: combine_undef_v8i16:
; SSE: # %bb.0:
; SSE-NEXT: paddsw %xmm0, %xmm0
; SSE-NEXT: pcmpeqd %xmm0, %xmm0
; SSE-NEXT: retq
;
; AVX-LABEL: combine_undef_v8i16:
; AVX: # %bb.0:
; AVX-NEXT: vpaddsw %xmm0, %xmm0, %xmm0
; AVX-NEXT: vpcmpeqd %xmm0, %xmm0, %xmm0
; AVX-NEXT: retq
%res = call <8 x i16> @llvm.sadd.sat.v8i16(<8 x i16> undef, <8 x i16> %a0)
ret <8 x i16> %res
@ -68,14 +62,12 @@ define <8 x i16> @combine_constfold_v8i16() {
define <8 x i16> @combine_constfold_undef_v8i16() {
; SSE-LABEL: combine_constfold_undef_v8i16:
; SSE: # %bb.0:
; SSE-NEXT: movdqa {{.*#+}} xmm0 = <u,1,u,65535,65535,65281,32776,1>
; SSE-NEXT: paddsw {{.*}}(%rip), %xmm0
; SSE-NEXT: movaps {{.*#+}} xmm0 = [65535,65535,65535,65534,0,65280,32768,0]
; SSE-NEXT: retq
;
; AVX-LABEL: combine_constfold_undef_v8i16:
; AVX: # %bb.0:
; AVX-NEXT: vmovdqa {{.*#+}} xmm0 = <u,1,u,65535,65535,65281,32776,1>
; AVX-NEXT: vpaddsw {{.*}}(%rip), %xmm0, %xmm0
; AVX-NEXT: vmovaps {{.*#+}} xmm0 = [65535,65535,65535,65534,0,65280,32768,0]
; AVX-NEXT: retq
%res = call <8 x i16> @llvm.sadd.sat.v8i16(<8 x i16> <i16 undef, i16 1, i16 undef, i16 65535, i16 -1, i16 -255, i16 -32760, i16 1>, <8 x i16> <i16 1, i16 undef, i16 undef, i16 65535, i16 1, i16 65535, i16 -10, i16 65535>)
ret <8 x i16> %res

12
llvm/test/CodeGen/X86/combine-add-usat.ll
View File

@ -15,9 +15,7 @@ declare <8 x i16> @llvm.uadd.sat.v8i16(<8 x i16>, <8 x i16>)
define i32 @combine_undef_i32(i32 %a0) {
; CHECK-LABEL: combine_undef_i32:
; CHECK: # %bb.0:
; CHECK-NEXT: addl %eax, %edi
; CHECK-NEXT: movl $-1, %eax
; CHECK-NEXT: cmovael %edi, %eax
; CHECK-NEXT: retq
%res = call i32 @llvm.uadd.sat.i32(i32 %a0, i32 undef)
ret i32 %res
@ -26,12 +24,12 @@ define i32 @combine_undef_i32(i32 %a0) {
define <8 x i16> @combine_undef_v8i16(<8 x i16> %a0) {
; SSE-LABEL: combine_undef_v8i16:
; SSE: # %bb.0:
; SSE-NEXT: paddusw %xmm0, %xmm0
; SSE-NEXT: pcmpeqd %xmm0, %xmm0
; SSE-NEXT: retq
;
; AVX-LABEL: combine_undef_v8i16:
; AVX: # %bb.0:
; AVX-NEXT: vpaddusw %xmm0, %xmm0, %xmm0
; AVX-NEXT: vpcmpeqd %xmm0, %xmm0, %xmm0
; AVX-NEXT: retq
%res = call <8 x i16> @llvm.uadd.sat.v8i16(<8 x i16> undef, <8 x i16> %a0)
ret <8 x i16> %res
@ -64,14 +62,12 @@ define <8 x i16> @combine_constfold_v8i16() {
define <8 x i16> @combine_constfold_undef_v8i16() {
; SSE-LABEL: combine_constfold_undef_v8i16:
; SSE: # %bb.0:
; SSE-NEXT: movdqa {{.*#+}} xmm0 = <u,1,u,65535,65535,65281,1,1>
; SSE-NEXT: paddusw {{.*}}(%rip), %xmm0
; SSE-NEXT: movaps {{.*#+}} xmm0 = [65535,65535,65535,65535,65535,65535,2,65535]
; SSE-NEXT: retq
;
; AVX-LABEL: combine_constfold_undef_v8i16:
; AVX: # %bb.0:
; AVX-NEXT: vmovdqa {{.*#+}} xmm0 = <u,1,u,65535,65535,65281,1,1>
; AVX-NEXT: vpaddusw {{.*}}(%rip), %xmm0, %xmm0
; AVX-NEXT: vmovaps {{.*#+}} xmm0 = [65535,65535,65535,65535,65535,65535,2,65535]
; AVX-NEXT: retq
%res = call <8 x i16> @llvm.uadd.sat.v8i16(<8 x i16> <i16 undef, i16 1, i16 undef, i16 65535, i16 -1, i16 -255, i16 -65535, i16 1>, <8 x i16> <i16 1, i16 undef, i16 undef, i16 65535, i16 1, i16 65535, i16 1, i16 65535>)
ret <8 x i16> %res

10
llvm/test/CodeGen/X86/combine-sub-ssat.ll
View File

@ -16,12 +16,6 @@ define i32 @combine_undef_i32(i32 %a0) {
; CHECK-LABEL: combine_undef_i32:
; CHECK: # %bb.0:
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: movl %edi, %ecx
; CHECK-NEXT: subl %eax, %ecx
; CHECK-NEXT: setns %al
; CHECK-NEXT: addl $2147483647, %eax # imm = 0x7FFFFFFF
; CHECK-NEXT: subl %eax, %edi
; CHECK-NEXT: cmovnol %edi, %eax
; CHECK-NEXT: retq
%res = call i32 @llvm.ssub.sat.i32(i32 %a0, i32 undef)
ret i32 %res
@ -30,12 +24,12 @@ define i32 @combine_undef_i32(i32 %a0) {
define <8 x i16> @combine_undef_v8i16(<8 x i16> %a0) {
; SSE-LABEL: combine_undef_v8i16:
; SSE: # %bb.0:
; SSE-NEXT: psubsw %xmm0, %xmm0
; SSE-NEXT: xorps %xmm0, %xmm0
; SSE-NEXT: retq
;
; AVX-LABEL: combine_undef_v8i16:
; AVX: # %bb.0:
; AVX-NEXT: vpsubsw %xmm0, %xmm0, %xmm0
; AVX-NEXT: vxorps %xmm0, %xmm0, %xmm0
; AVX-NEXT: retq
%res = call <8 x i16> @llvm.ssub.sat.v8i16(<8 x i16> undef, <8 x i16> %a0)
ret <8 x i16> %res

6
llvm/test/CodeGen/X86/combine-sub-usat.ll
View File

@ -16,8 +16,6 @@ define i32 @combine_undef_i32(i32 %a0) {
; CHECK-LABEL: combine_undef_i32:
; CHECK: # %bb.0:
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: subl %eax, %edi
; CHECK-NEXT: cmovael %edi, %eax
; CHECK-NEXT: retq
%res = call i32 @llvm.usub.sat.i32(i32 %a0, i32 undef)
ret i32 %res
@ -26,12 +24,12 @@ define i32 @combine_undef_i32(i32 %a0) {
define <8 x i16> @combine_undef_v8i16(<8 x i16> %a0) {
; SSE-LABEL: combine_undef_v8i16:
; SSE: # %bb.0:
; SSE-NEXT: psubusw %xmm0, %xmm0
; SSE-NEXT: xorps %xmm0, %xmm0
; SSE-NEXT: retq
;
; AVX-LABEL: combine_undef_v8i16:
; AVX: # %bb.0:
; AVX-NEXT: vpsubusw %xmm0, %xmm0, %xmm0
; AVX-NEXT: vxorps %xmm0, %xmm0, %xmm0
; AVX-NEXT: retq
%res = call <8 x i16> @llvm.usub.sat.v8i16(<8 x i16> undef, <8 x i16> %a0)
ret <8 x i16> %res