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[DAGCombine] Make sure we check the ResNo from UADDO before combining

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Summary: UADDO has 2 result, and one must check the result no before doing any kind of combine. Without it, the transform is invalid.

Reviewers: joerg

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D34088

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305162 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Amaury Sechet 2017-06-11 11:36:38 +00:00
parent 8177dcd104
commit ddcf5ab29b
2 changed files with 26 additions and 1 deletions
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3
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -2217,7 +2217,8 @@ SDValue DAGCombiner::visitADDCARRYLike(SDValue N0, SDValue N1, SDValue CarryIn,
SDNode *N) {
// Iff the flag result is dead:
// (addcarry (add|uaddo X, Y), 0, Carry) -> (addcarry X, Y, Carry)
if ((N0.getOpcode() == ISD::ADD || N0.getOpcode() == ISD::UADDO) &&
if ((N0.getOpcode() == ISD::ADD ||
(N0.getOpcode() == ISD::UADDO && N0.getResNo() == 0)) &&
isNullConstant(N1) && !N->hasAnyUseOfValue(1))
return DAG.getNode(ISD::ADDCARRY, SDLoc(N), N->getVTList(),
N0.getOperand(0), N0.getOperand(1), CarryIn);

24
test/CodeGen/X86/addcarry.ll
View File

@ -81,6 +81,30 @@ entry:
ret void
}
define i8 @e(i32* nocapture %a, i32 %b) nounwind {
; CHECK-LABEL: e:
; CHECK: # BB#0:
; CHECK-NEXT: # kill: %ESI<def> %ESI<kill> %RSI<def>
; CHECK-NEXT: movl (%rdi), %ecx
; CHECK-NEXT: leal (%rsi,%rcx), %edx
; CHECK-NEXT: addl %esi, %edx
; CHECK-NEXT: setb %al
; CHECK-NEXT: addl %esi, %ecx
; CHECK-NEXT: movl %edx, (%rdi)
; CHECK-NEXT: adcb $0, %al
; CHECK-NEXT: retq
%1 = load i32, i32* %a, align 4
%2 = add i32 %1, %b
%3 = icmp ult i32 %2, %b
%4 = zext i1 %3 to i8
%5 = add i32 %2, %b
store i32 %5, i32* %a, align 4
%6 = icmp ult i32 %5, %b
%7 = zext i1 %6 to i8
%8 = add nuw nsw i8 %7, %4
ret i8 %8
}
%scalar = type { [4 x i64] }
define %scalar @pr31719(%scalar* nocapture readonly %this, %scalar %arg.b) {