[SelectionDAG][X86] Use disjoint flag in SelectionDAG::isADDLike. (llvm#76847)

Keep the haveNoCommonBitsSet check because we haven't started inferring
the flag yet.

I've added tests for two transforms, but these are not the only
transforms that use isADDLike.

Author: topperc

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -7987,7 +7987,7 @@ SDValue DAGCombiner::visitOR(SDNode *N) {
 
   // If OR can be rewritten into ADD, try combines based on ADD.
   if ((!LegalOperations || TLI.isOperationLegal(ISD::ADD, VT)) &&
-      DAG.haveNoCommonBitsSet(N0, N1))
+      DAG.isADDLike(SDValue(N, 0)))
     if (SDValue Combined = visitADDLike(N))
       return Combined;
 

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -5088,7 +5088,8 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
 bool SelectionDAG::isADDLike(SDValue Op) const {
   unsigned Opcode = Op.getOpcode();
   if (Opcode == ISD::OR)
-    return haveNoCommonBitsSet(Op.getOperand(0), Op.getOperand(1));
+    return Op->getFlags().hasDisjoint() ||
+           haveNoCommonBitsSet(Op.getOperand(0), Op.getOperand(1));
   if (Opcode == ISD::XOR)
     return isMinSignedConstant(Op.getOperand(1));
   return false;

llvm/test/CodeGen/X86/addsub-constant-folding.ll

@@ -1141,3 +1141,39 @@ define <4 x i32> @vec_const_sub_const_sub_nonsplat(<4 x i32> %arg) {
   %t1 = sub <4 x i32> <i32 2, i32 3, i32 undef, i32 2>, %t0
   ret <4 x i32> %t1
 }
+
+; (x|c1)+c2 where (x|c1) is addlike
+define i32 @add_const_disjoint_or_const(i32 %arg) {
+; X86-LABEL: add_const_disjoint_or_const:
+; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    addl $10, %eax
+; X86-NEXT:    retl
+;
+; X64-LABEL: add_const_disjoint_or_const:
+; X64:       # %bb.0:
+; X64-NEXT:    # kill: def $edi killed $edi def $rdi
+; X64-NEXT:    leal 10(%rdi), %eax
+; X64-NEXT:    retq
+  %t0 = or disjoint i32 %arg, 8
+  %t1 = add i32 %t0, 2
+  ret i32 %t1
+}
+
+; (x+c1)|c2 where the outer or is addlike
+define i32 @disjoint_or_const_add_const(i32 %arg) {
+; X86-LABEL: disjoint_or_const_add_const:
+; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    addl $10, %eax
+; X86-NEXT:    retl
+;
+; X64-LABEL: disjoint_or_const_add_const:
+; X64:       # %bb.0:
+; X64-NEXT:    # kill: def $edi killed $edi def $rdi
+; X64-NEXT:    leal 10(%rdi), %eax
+; X64-NEXT:    retq
+  %t0 = add i32 %arg, 8
+  %t1 = or disjoint i32 %t0, 2
+  ret i32 %t1
+}

llvm/test/CodeGen/X86/or-lea.ll

@@ -825,3 +825,23 @@ entry:
   %or = or i64 %sub, 549755813889   ; 0x8000000001
   ret i64 %or
 }
+
+define i32 @or_shift1_disjoint(i32 %x, i32 %y) {
+; X86-LABEL: or_shift1_disjoint:
+; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    addl %eax, %eax
+; X86-NEXT:    orl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    retl
+;
+; X64-LABEL: or_shift1_disjoint:
+; X64:       # %bb.0:
+; X64-NEXT:    # kill: def $esi killed $esi def $rsi
+; X64-NEXT:    # kill: def $edi killed $edi def $rdi
+; X64-NEXT:    leal (%rsi,%rdi,2), %eax
+; X64-NEXT:    retq
+  %shl = shl i32 %x, 1
+  %or = or disjoint i32 %y, %shl
+  ret i32 %or
+}
+