[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

[Chris Lattner]

Changes in directory llvm/lib/CodeGen/SelectionDAG:

SelectionDAGISel.cpp updated: 1.37 -> 1.38
---
Log message:

Turn -0.0 - X -> fneg


---
Diffs of the changes:  (+13 -1)

 SelectionDAGISel.cpp |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletion(-)


Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.37 llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.38
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.37	Thu Mar 31 15:24:06 2005
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp	Fri Apr  1 23:04:50 2005
@@ -314,7 +314,7 @@
   //
   void visitBinary(User &I, unsigned Opcode);
   void visitAdd(User &I) { visitBinary(I, ISD::ADD); }
-  void visitSub(User &I) { visitBinary(I, ISD::SUB); }
+  void visitSub(User &I);
   void visitMul(User &I) { visitBinary(I, ISD::MUL); }
   void visitDiv(User &I) {
     visitBinary(I, I.getType()->isUnsigned() ? ISD::UDIV : ISD::SDIV);
@@ -454,6 +454,18 @@
   }
 }
 
+void SelectionDAGLowering::visitSub(User &I) {
+  // -0.0 - X --> fneg
+  if (ConstantFP *CFP = dyn_cast<ConstantFP>(I.getOperand(0)))
+    if (CFP->isExactlyValue(-0.0)) {
+      SDOperand Op2 = getValue(I.getOperand(1));
+      setValue(&I, DAG.getNode(ISD::FNEG, Op2.getValueType(), Op2));
+      return;
+    }
+
+  visitBinary(I, ISD::SUB);
+}
+
 void SelectionDAGLowering::visitBinary(User &I, unsigned Opcode) {
   SDOperand Op1 = getValue(I.getOperand(0));
   SDOperand Op2 = getValue(I.getOperand(1));