[X86] Don't transform atomic-load-add into an inc/dec when inc/dec is slow
llvm-svn: 219357
diff --git a/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp b/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
index 7665bea..c42a05f 100644
--- a/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
+++ b/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
@@ -1706,7 +1706,8 @@
static SDValue getAtomicLoadArithTargetConstant(SelectionDAG *CurDAG,
SDLoc dl,
enum AtomicOpc &Op, MVT NVT,
- SDValue Val) {
+ SDValue Val,
+ const X86Subtarget *Subtarget) {
if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Val)) {
int64_t CNVal = CN->getSExtValue();
// Quit if not 32-bit imm.
@@ -1721,7 +1722,7 @@
// For atomic-load-add, we could do some optimizations.
if (Op == ADD) {
// Translate to INC/DEC if ADD by 1 or -1.
- if ((CNVal == 1) || (CNVal == -1)) {
+ if (((CNVal == 1) || (CNVal == -1)) && !Subtarget->slowIncDec()) {
Op = (CNVal == 1) ? INC : DEC;
// No more constant operand after being translated into INC/DEC.
return SDValue();
@@ -1793,7 +1794,7 @@
break;
}
- Val = getAtomicLoadArithTargetConstant(CurDAG, dl, Op, NVT, Val);
+ Val = getAtomicLoadArithTargetConstant(CurDAG, dl, Op, NVT, Val, Subtarget);
bool isUnOp = !Val.getNode();
bool isCN = Val.getNode() && (Val.getOpcode() == ISD::TargetConstant);