[FPEnv] Don't transform FSUB(-0,X)->FNEG(X) in SelectionDAGBuilder.
This patch stops unconditionally transforming FSUB(-0,X) into an FNEG(X) while building the DAG. There is also one small change to handle the new FSUB(-0,X) similarly to FNEG(X) in the AMDGPU backend.
Differential Revision: https://reviews.llvm.org/D84056
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index c2a284a..9c1517e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3005,20 +3005,6 @@
DAG.setRoot(DAG.getNode(ISD::TRAP, getCurSDLoc(), MVT::Other, DAG.getRoot()));
}
-void SelectionDAGBuilder::visitFSub(const User &I) {
- // -0.0 - X --> fneg
- Type *Ty = I.getType();
- if (isa<Constant>(I.getOperand(0)) &&
- I.getOperand(0) == ConstantFP::getZeroValueForNegation(Ty)) {
- SDValue Op2 = getValue(I.getOperand(1));
- setValue(&I, DAG.getNode(ISD::FNEG, getCurSDLoc(),
- Op2.getValueType(), Op2));
- return;
- }
-
- visitBinary(I, ISD::FSUB);
-}
-
void SelectionDAGBuilder::visitUnary(const User &I, unsigned Opcode) {
SDNodeFlags Flags;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index f0b7fb0..7bad055 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -692,7 +692,7 @@
void visitAdd(const User &I) { visitBinary(I, ISD::ADD); }
void visitFAdd(const User &I) { visitBinary(I, ISD::FADD); }
void visitSub(const User &I) { visitBinary(I, ISD::SUB); }
- void visitFSub(const User &I);
+ void visitFSub(const User &I) { visitBinary(I, ISD::FSUB); }
void visitMul(const User &I) { visitBinary(I, ISD::MUL); }
void visitFMul(const User &I) { visitBinary(I, ISD::FMUL); }
void visitURem(const User &I) { visitBinary(I, ISD::UREM); }
