[PATCH] D29564: [DAGCombiner] (add X, (adde Y, 0, Carry)) -> (adde X, Y, Carry)

[Amaury SECHET via Phabricator via llvm-commits]

deadalnix created this revision.

This is extracted from https://reviews.llvm.org/D29443 .


https://reviews.llvm.org/D29564

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  test/CodeGen/X86/adde-carry.ll


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)
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();
 }
 


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