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

[Chris Lattner]

Changes in directory llvm/lib/CodeGen/SelectionDAG:

SelectionDAG.cpp updated: 1.50 -> 1.51
---
Log message:

Don't rely on doubles comparing identical to each other, which doesn't work
for 0.0 and -0.0.


---
Diffs of the changes:  (+19 -4)

 SelectionDAG.cpp |   23 +++++++++++++++++++----
 1 files changed, 19 insertions(+), 4 deletions(-)


Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.50 llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.51
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:1.50	Sat Jan 22 22:39:44 2005
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp	Thu Feb 17 14:17:32 2005
@@ -196,10 +196,15 @@
     Constants.erase(std::make_pair(cast<ConstantSDNode>(N)->getValue(),
                                    N->getValueType(0)));
     break;
-  case ISD::ConstantFP:
-    ConstantFPs.erase(std::make_pair(cast<ConstantFPSDNode>(N)->getValue(),
-                                     N->getValueType(0)));
+  case ISD::ConstantFP: {
+    union {
+      double DV;
+      uint64_t IV;
+    };
+    DV = cast<ConstantFPSDNode>(N)->getValue();
+    ConstantFPs.erase(std::make_pair(IV, N->getValueType(0)));
     break;
+  }
   case ISD::GlobalAddress:
     GlobalValues.erase(cast<GlobalAddressSDNode>(N)->getGlobal());
     break;
@@ -299,7 +304,17 @@
   if (VT == MVT::f32)
     Val = (float)Val;  // Mask out extra precision.
 
-  SDNode *&N = ConstantFPs[std::make_pair(Val, VT)];
+  // Do the map lookup using the actual bit pattern for the floating point
+  // value, so that we don't have problems with 0.0 comparing equal to -0.0, and
+  // we don't have issues with SNANs.
+  union {
+    double DV;
+    uint64_t IV;
+  };
+  
+  DV = Val;
+
+  SDNode *&N = ConstantFPs[std::make_pair(IV, VT)];
   if (N) return SDOperand(N, 0);
   N = new ConstantFPSDNode(Val, VT);
   AllNodes.push_back(N);