Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp =================================================================== --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -1834,6 +1834,13 @@ } } + // (add X, (adde Y, 0, Carry)) -> (adde X, Y, Carry) + if (N1.getOpcode() == ISD::ADDE && + N1->hasOneUse() && + isNullConstant(N1.getOperand(1))) + return DAG.getNode(ISD::ADDE, DL, DAG.getVTList(VT, MVT::Glue), + N0, N1->getOperand(0), N1->getOperand(2)); + return SDValue(); } Index: test/CodeGen/X86/adde-carry.ll =================================================================== --- test/CodeGen/X86/adde-carry.ll +++ test/CodeGen/X86/adde-carry.ll @@ -93,17 +93,16 @@ ; CHECK-NEXT: sbbq %r10, %r10 ; CHECK-NEXT: andl $1, %r10d ; CHECK-NEXT: addq 8(%rsi), %rcx -; CHECK-NEXT: sbbq %r11, %r11 -; CHECK-NEXT: andl $1, %r11d -; CHECK-NEXT: addq %r10, %rcx -; CHECK-NEXT: adcq $0, %r11 -; CHECK-NEXT: addq 16(%rsi), %r8 ; CHECK-NEXT: sbbq %rax, %rax ; CHECK-NEXT: andl $1, %eax -; CHECK-NEXT: addq %r11, %r8 +; CHECK-NEXT: addq %r10, %rcx ; CHECK-NEXT: adcq $0, %rax +; CHECK-NEXT: addq 16(%rsi), %r8 +; CHECK-NEXT: sbbq %r10, %r10 +; CHECK-NEXT: andl $1, %r10d ; CHECK-NEXT: addq 24(%rsi), %r9 -; CHECK-NEXT: addq %rax, %r9 +; CHECK-NEXT: addq %rax, %r8 +; CHECK-NEXT: adcq %r10, %r9 ; CHECK-NEXT: movq %rdx, (%rdi) ; CHECK-NEXT: movq %rcx, 8(%rdi) ; CHECK-NEXT: movq %r8, 16(%rdi)