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[X86] Make sure we use FSUB instruction as the reference for operand order in isAddSubOrSubAdd when recognizing subadd

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The FADD part of the addsub/subadd pattern can have its operands commuted, but when checking for fsubadd we were using the fadd as reference and commuting the fsub node.

llvm-svn: 327660
This commit is contained in:
Craig Topper 2018-03-15 20:30:54 +00:00
parent d0a1cd1c1a
commit f111607f06
2 changed files with 31 additions and 9 deletions
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16
lib/Target/X86/X86ISelLowering.cpp
View File

@ -30494,10 +30494,18 @@ static bool isAddSubOrSubAdd(SDNode *N, const X86Subtarget &Subtarget,
// Ensure that both operations have the same operands. Note that we can
// commute the FADD operands.
SDValue LHS = V1->getOperand(0), RHS = V1->getOperand(1);
if ((V2->getOperand(0) != LHS || V2->getOperand(1) != RHS) &&
(V2->getOperand(0) != RHS || V2->getOperand(1) != LHS))
return false;
SDValue LHS, RHS;
if (ExpectedOpcode == ISD::FSUB) {
LHS = V1->getOperand(0); RHS = V1->getOperand(1);
if ((V2->getOperand(0) != LHS || V2->getOperand(1) != RHS) &&
(V2->getOperand(0) != RHS || V2->getOperand(1) != LHS))
return false;
} else {
LHS = V2->getOperand(0); RHS = V2->getOperand(1);
if ((V1->getOperand(0) != LHS || V1->getOperand(1) != RHS) &&
(V1->getOperand(0) != RHS || V1->getOperand(1) != LHS))
return false;
}
// We're looking for blends between FADD and FSUB nodes. We insist on these
// nodes being lined up in a specific expected pattern.

24
test/CodeGen/X86/fmsubadd-combine.ll
View File

@ -134,14 +134,28 @@ entry:
; This should not be matched to fmsubadd because the mul is on the wrong side of the fsub.
define <2 x double> @mul_subadd_bad_commute(<2 x double> %A, <2 x double> %B, <2 x double> %C) #0 {
; FMA3-LABEL: mul_subadd_bad_commute:
; FMA3: # %bb.0: # %entry
; FMA3-NEXT: vfmsubadd213pd {{.*#+}} xmm0 = (xmm1 * xmm0) -/+ xmm2
; FMA3-NEXT: retq
; FMA3_256-LABEL: mul_subadd_bad_commute:
; FMA3_256: # %bb.0: # %entry
; FMA3_256-NEXT: vmulpd %xmm1, %xmm0, %xmm0
; FMA3_256-NEXT: vsubpd %xmm0, %xmm2, %xmm1
; FMA3_256-NEXT: vaddpd %xmm2, %xmm0, %xmm0
; FMA3_256-NEXT: vblendpd {{.*#+}} xmm0 = xmm0[0],xmm1[1]
; FMA3_256-NEXT: retq
;
; FMA3_512-LABEL: mul_subadd_bad_commute:
; FMA3_512: # %bb.0: # %entry
; FMA3_512-NEXT: vmulpd %xmm1, %xmm0, %xmm0
; FMA3_512-NEXT: vsubpd %xmm0, %xmm2, %xmm1
; FMA3_512-NEXT: vaddpd %xmm2, %xmm0, %xmm0
; FMA3_512-NEXT: vmovsd {{.*#+}} xmm0 = xmm0[0],xmm1[1]
; FMA3_512-NEXT: retq
;
; FMA4-LABEL: mul_subadd_bad_commute:
; FMA4: # %bb.0: # %entry
; FMA4-NEXT: vfmsubaddpd %xmm2, %xmm1, %xmm0, %xmm0
; FMA4-NEXT: vmulpd %xmm1, %xmm0, %xmm0
; FMA4-NEXT: vsubpd %xmm0, %xmm2, %xmm1
; FMA4-NEXT: vaddpd %xmm2, %xmm0, %xmm0
; FMA4-NEXT: vblendpd {{.*#+}} xmm0 = xmm0[0],xmm1[1]
; FMA4-NEXT: retq
entry:
%AB = fmul <2 x double> %A, %B