DAGCombiner: don't duplicate (fmul x, c) in visitFNEG if fneg is free
For targets with a free fneg, this fold is always a net loss if it
ends up duplicating the multiply, so definitely avoid it.
This might be true for some targets without a free fneg too, but
I'll leave that for future investigation.
llvm-svn: 239167
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 0619c94..d5b2f36 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -8781,7 +8781,8 @@
}
// (fneg (fmul c, x)) -> (fmul -c, x)
- if (N0.getOpcode() == ISD::FMUL) {
+ if (N0.getOpcode() == ISD::FMUL &&
+ (N0.getNode()->hasOneUse() || !TLI.isFNegFree(VT))) {
ConstantFPSDNode *CFP1 = dyn_cast<ConstantFPSDNode>(N0.getOperand(1));
if (CFP1) {
APFloat CVal = CFP1->getValueAPF();