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[SelectionDAG] Propagate poison in getNode with two operands if the input is poison. #135387

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Merged
merged 8 commits into from
Apr 17, 2025
Merged

[SelectionDAG] Propagate poison in getNode with two operands if the input is poison. #135387

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273f4de
return POISON value in the getNode() in input is poison
diggerlin Apr 11, 2025
bea1bbd
address comment
diggerlin Apr 14, 2025
24661e2
using getPOISON(VT) instead of N2
diggerlin Apr 15, 2025
bd1e9e9
minor change
diggerlin Apr 15, 2025
f0b06ba
address comment
diggerlin Apr 16, 2025
7c196c5
Update llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
diggerlin Apr 16, 2025
a6e0c88
Update llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
diggerlin Apr 16, 2025
24bc9f0
add a nit comment
diggerlin Apr 16, 2025
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13 changes: 10 additions & 3 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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Expand Up @@ -7601,16 +7601,23 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
case ISD::SDIV:
case ISD::UREM:
case ISD::SREM:
return getUNDEF(VT); // fold op(arg1, undef) -> undef
// fold op(arg1, undef) -> undef, // fold op(arg1, poison) -> poison.
return N2.getOpcode() == ISD::POISON
? getPOISON(VT)
: getUNDEF(VT);
case ISD::MUL:
case ISD::AND:
case ISD::SSUBSAT:
case ISD::USUBSAT:
return getConstant(0, DL, VT); // fold op(arg1, undef) -> 0
// fold op(arg1, undef) -> 0, fold op(arg1, poison) -> poison.
return N2.getOpcode() == ISD::POISON
? getPOISON(VT)
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@arsenm arsenm Apr 12, 2025

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Can return N2 instead of returning doing a new getPOISON

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@diggerlin diggerlin Apr 15, 2025 •
edited
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I do not think we can guarantee N2.getValueType() is same as VT. using N2 instead of N2 is a risk,

: getConstant(0, DL, VT);
case ISD::OR:
case ISD::SADDSAT:
case ISD::UADDSAT:
return getAllOnesConstant(DL, VT);
return N2.getOpcode() == ISD::POISON ? getPOISON(VT)
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@amy-kwan amy-kwan Apr 16, 2025

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Nit: maybe we can add a similar comment, like the other cases?

: getAllOnesConstant(DL, VT);
}
}

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24 changes: 12 additions & 12 deletions llvm/test/CodeGen/X86/half.ll
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Expand Up @@ -1991,8 +1991,8 @@ define void @pr63114() {
; CHECK-LIBCALL-LABEL: pr63114:
; CHECK-LIBCALL: # %bb.0:
; CHECK-LIBCALL-NEXT: movdqu (%rax), %xmm4
; CHECK-LIBCALL-NEXT: pshufhw {{.*#+}} xmm0 = xmm4[0,1,2,3,4,5,7,7]
; CHECK-LIBCALL-NEXT: pshufd {{.*#+}} xmm0 = xmm0[0,2,2,3]
; CHECK-LIBCALL-NEXT: pshuflw {{.*#+}} xmm0 = xmm4[0,1,3,3,4,5,6,7]
; CHECK-LIBCALL-NEXT: pshufd {{.*#+}} xmm0 = xmm0[0,0,2,1]
; CHECK-LIBCALL-NEXT: movdqa {{.*#+}} xmm1 = [65535,65535,65535,0,65535,65535,65535,65535]
; CHECK-LIBCALL-NEXT: pand %xmm1, %xmm0
; CHECK-LIBCALL-NEXT: movq {{.*#+}} xmm2 = [0,0,0,15360,0,0,0,0]
Expand All @@ -2001,8 +2001,8 @@ define void @pr63114() {
; CHECK-LIBCALL-NEXT: pand %xmm3, %xmm0
; CHECK-LIBCALL-NEXT: movdqa {{.*#+}} xmm5 = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,60]
; CHECK-LIBCALL-NEXT: por %xmm5, %xmm0
; CHECK-LIBCALL-NEXT: pshuflw {{.*#+}} xmm6 = xmm4[0,1,3,3,4,5,6,7]
; CHECK-LIBCALL-NEXT: pshufd {{.*#+}} xmm6 = xmm6[0,0,2,1]
; CHECK-LIBCALL-NEXT: pshufhw {{.*#+}} xmm6 = xmm4[0,1,2,3,4,5,7,7]
; CHECK-LIBCALL-NEXT: pshufd {{.*#+}} xmm6 = xmm6[0,2,2,3]
; CHECK-LIBCALL-NEXT: pand %xmm1, %xmm6
; CHECK-LIBCALL-NEXT: por %xmm2, %xmm6
; CHECK-LIBCALL-NEXT: pand %xmm3, %xmm6
Expand All @@ -2020,8 +2020,8 @@ define void @pr63114() {
; CHECK-LIBCALL-NEXT: por %xmm5, %xmm7
; CHECK-LIBCALL-NEXT: movdqu %xmm7, 0
; CHECK-LIBCALL-NEXT: movdqu %xmm4, 32
; CHECK-LIBCALL-NEXT: movdqu %xmm6, 16
; CHECK-LIBCALL-NEXT: movdqu %xmm0, 48
; CHECK-LIBCALL-NEXT: movdqu %xmm6, 48
; CHECK-LIBCALL-NEXT: movdqu %xmm0, 16
; CHECK-LIBCALL-NEXT: retq
;
; BWON-F16C-LABEL: pr63114:
Expand Down Expand Up @@ -2056,8 +2056,8 @@ define void @pr63114() {
; CHECK-I686-LABEL: pr63114:
; CHECK-I686: # %bb.0:
; CHECK-I686-NEXT: movdqu (%eax), %xmm6
; CHECK-I686-NEXT: pshufhw {{.*#+}} xmm0 = xmm6[0,1,2,3,4,5,7,7]
; CHECK-I686-NEXT: pshufd {{.*#+}} xmm0 = xmm0[0,2,2,3]
; CHECK-I686-NEXT: pshuflw {{.*#+}} xmm0 = xmm6[0,1,3,3,4,5,6,7]
; CHECK-I686-NEXT: pshufd {{.*#+}} xmm0 = xmm0[0,0,2,1]
; CHECK-I686-NEXT: movdqa {{.*#+}} xmm1 = [65535,65535,65535,0,65535,65535,65535,65535]
; CHECK-I686-NEXT: pand %xmm1, %xmm0
; CHECK-I686-NEXT: movq {{.*#+}} xmm2 = [0,0,0,15360,0,0,0,0]
Expand All @@ -2066,8 +2066,8 @@ define void @pr63114() {
; CHECK-I686-NEXT: pand %xmm3, %xmm0
; CHECK-I686-NEXT: movdqa {{.*#+}} xmm4 = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,60]
; CHECK-I686-NEXT: por %xmm4, %xmm0
; CHECK-I686-NEXT: pshuflw {{.*#+}} xmm5 = xmm6[0,1,3,3,4,5,6,7]
; CHECK-I686-NEXT: pshufd {{.*#+}} xmm5 = xmm5[0,0,2,1]
; CHECK-I686-NEXT: pshufhw {{.*#+}} xmm5 = xmm6[0,1,2,3,4,5,7,7]
; CHECK-I686-NEXT: pshufd {{.*#+}} xmm5 = xmm5[0,2,2,3]
; CHECK-I686-NEXT: pand %xmm1, %xmm5
; CHECK-I686-NEXT: por %xmm2, %xmm5
; CHECK-I686-NEXT: pand %xmm3, %xmm5
Expand All @@ -2085,8 +2085,8 @@ define void @pr63114() {
; CHECK-I686-NEXT: por %xmm4, %xmm7
; CHECK-I686-NEXT: movdqu %xmm7, 0
; CHECK-I686-NEXT: movdqu %xmm6, 32
; CHECK-I686-NEXT: movdqu %xmm5, 16
; CHECK-I686-NEXT: movdqu %xmm0, 48
; CHECK-I686-NEXT: movdqu %xmm5, 48
; CHECK-I686-NEXT: movdqu %xmm0, 16
; CHECK-I686-NEXT: retl
%1 = load <24 x half>, ptr poison, align 2
%2 = shufflevector <24 x half> %1, <24 x half> poison, <8 x i32> <i32 2, i32 5, i32 8, i32 11, i32 14, i32 17, i32 20, i32 23>
Expand Down
12 changes: 0 additions & 12 deletions llvm/test/CodeGen/X86/poison-ops.ll
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Expand Up @@ -68,7 +68,6 @@ define <4 x i32> @sub_poison_lhs_vec(<4 x i32> %x) {
define i32 @mul_poison_rhs(i32 %x) {
; CHECK-LABEL: mul_poison_rhs:
; CHECK: # %bb.0:
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: retq
%r = mul i32 %x, poison
ret i32 %r
Expand All @@ -77,7 +76,6 @@ define i32 @mul_poison_rhs(i32 %x) {
define <4 x i32> @mul_poison_rhs_vec(<4 x i32> %x) {
; CHECK-LABEL: mul_poison_rhs_vec:
; CHECK: # %bb.0:
; CHECK-NEXT: xorps %xmm0, %xmm0
; CHECK-NEXT: retq
%r = mul <4 x i32> %x, poison
ret <4 x i32> %r
Expand All @@ -86,7 +84,6 @@ define <4 x i32> @mul_poison_rhs_vec(<4 x i32> %x) {
define i32 @mul_poison_lhs(i32 %x) {
; CHECK-LABEL: mul_poison_lhs:
; CHECK: # %bb.0:
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: retq
%r = mul i32 poison, %x
ret i32 %r
Expand All @@ -95,7 +92,6 @@ define i32 @mul_poison_lhs(i32 %x) {
define <4 x i32> @mul_poison_lhs_vec(<4 x i32> %x) {
; CHECK-LABEL: mul_poison_lhs_vec:
; CHECK: # %bb.0:
; CHECK-NEXT: xorps %xmm0, %xmm0
; CHECK-NEXT: retq
%r = mul <4 x i32> poison, %x
ret <4 x i32> %r
Expand Down Expand Up @@ -342,7 +338,6 @@ define <4 x i32> @shl_poison_lhs_vec(<4 x i32> %x) {
define i32 @and_poison_rhs(i32 %x) {
; CHECK-LABEL: and_poison_rhs:
; CHECK: # %bb.0:
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: retq
%r = and i32 %x, poison
ret i32 %r
Expand All @@ -351,7 +346,6 @@ define i32 @and_poison_rhs(i32 %x) {
define <4 x i32> @and_poison_rhs_vec(<4 x i32> %x) {
; CHECK-LABEL: and_poison_rhs_vec:
; CHECK: # %bb.0:
; CHECK-NEXT: xorps %xmm0, %xmm0
; CHECK-NEXT: retq
%r = and <4 x i32> %x, poison
ret <4 x i32> %r
Expand All @@ -360,7 +354,6 @@ define <4 x i32> @and_poison_rhs_vec(<4 x i32> %x) {
define i32 @and_poison_lhs(i32 %x) {
; CHECK-LABEL: and_poison_lhs:
; CHECK: # %bb.0:
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: retq
%r = and i32 poison, %x
ret i32 %r
Expand All @@ -369,7 +362,6 @@ define i32 @and_poison_lhs(i32 %x) {
define <4 x i32> @and_poison_lhs_vec(<4 x i32> %x) {
; CHECK-LABEL: and_poison_lhs_vec:
; CHECK: # %bb.0:
; CHECK-NEXT: xorps %xmm0, %xmm0
; CHECK-NEXT: retq
%r = and <4 x i32> poison, %x
ret <4 x i32> %r
Expand All @@ -378,7 +370,6 @@ define <4 x i32> @and_poison_lhs_vec(<4 x i32> %x) {
define i32 @or_poison_rhs(i32 %x) {
; CHECK-LABEL: or_poison_rhs:
; CHECK: # %bb.0:
; CHECK-NEXT: movl $-1, %eax
; CHECK-NEXT: retq
%r = or i32 %x, poison
ret i32 %r
Expand All @@ -387,7 +378,6 @@ define i32 @or_poison_rhs(i32 %x) {
define <4 x i32> @or_poison_rhs_vec(<4 x i32> %x) {
; CHECK-LABEL: or_poison_rhs_vec:
; CHECK: # %bb.0:
; CHECK-NEXT: pcmpeqd %xmm0, %xmm0
; CHECK-NEXT: retq
%r = or <4 x i32> %x, poison
ret <4 x i32> %r
Expand All @@ -396,7 +386,6 @@ define <4 x i32> @or_poison_rhs_vec(<4 x i32> %x) {
define i32 @or_poison_lhs(i32 %x) {
; CHECK-LABEL: or_poison_lhs:
; CHECK: # %bb.0:
; CHECK-NEXT: movl $-1, %eax
; CHECK-NEXT: retq
%r = or i32 poison, %x
ret i32 %r
Expand All @@ -405,7 +394,6 @@ define i32 @or_poison_lhs(i32 %x) {
define <4 x i32> @or_poison_lhs_vec(<4 x i32> %x) {
; CHECK-LABEL: or_poison_lhs_vec:
; CHECK: # %bb.0:
; CHECK-NEXT: pcmpeqd %xmm0, %xmm0
; CHECK-NEXT: retq
%r = or <4 x i32> poison, %x
ret <4 x i32> %r
Expand Down
7 changes: 3 additions & 4 deletions llvm/test/CodeGen/X86/pr119158.ll
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Expand Up @@ -5,10 +5,9 @@ define dso_local void @foo() #1 {
; CHECK-LABEL: foo:
; CHECK: # %bb.0: # %newFuncRoot
; CHECK-NEXT: vpmovzxbd {{.*#+}} ymm0 = mem[0],zero,zero,zero,mem[1],zero,zero,zero,mem[2],zero,zero,zero,mem[3],zero,zero,zero,mem[4],zero,zero,zero,mem[5],zero,zero,zero,mem[6],zero,zero,zero,mem[7],zero,zero,zero
; CHECK-NEXT: vpbroadcastd {{.*#+}} ymm1 = [18,0,18,0,18,0,18,0,18,0,18,0,18,0,18,0]
; CHECK-NEXT: vpmaddwd %ymm1, %ymm0, %ymm0
; CHECK-NEXT: vpaddd {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %ymm0, %ymm0
; CHECK-NEXT: vpsrld $7, %ymm0, %ymm0
; CHECK-NEXT: vpbroadcastd {{.*#+}} ymm1 = [64,64,64,64,64,64,64,64]
; CHECK-NEXT: vpdpwssd {{\.?LCPI[0-9]+_[0-9]+}}(%rip){1to8}, %ymm0, %ymm1
; CHECK-NEXT: vpsrld $7, %ymm1, %ymm0
; CHECK-NEXT: vpackusdw %ymm0, %ymm0, %ymm0
; CHECK-NEXT: vpermq {{.*#+}} ymm0 = ymm0[0,2,1,3]
; CHECK-NEXT: vmovdqu %ymm0, (%rax)
Expand Down
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