[llvm-commits] CVS: llvm/lib/Transforms/Scalar/InstructionCombining.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.357 -> 1.358
---
Log message:

When transforming &A[i] < &A[j]  ->  i < j, make sure to perform the comparison
as a signed compare.  This patch may fix PR597: http://llvm.cs.uiuc.edu/PR597 , but is correct in any case.



---
Diffs of the changes:  (+11 -4)

 InstructionCombining.cpp |   15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)


Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.357 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.358
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.357	Thu Jul  7 15:40:38 2005
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Mon Jul 18 18:07:33 2005
@@ -2367,10 +2367,17 @@
       else if (NumDifferences == 1) {
         Value *LHSV = GEPLHS->getOperand(DiffOperand);
         Value *RHSV = GEPRHS->getOperand(DiffOperand);
-        if (LHSV->getType() != RHSV->getType())
-          LHSV = InsertNewInstBefore(new CastInst(LHSV, RHSV->getType(),
-                                                  LHSV->getName()+".c"), I);
-          return new SetCondInst(Cond, LHSV, RHSV);
+
+        // Convert the operands to signed values to make sure to perform a
+        // signed comparison.
+        const Type *NewTy = LHSV->getType()->getSignedVersion();
+        if (LHSV->getType() != NewTy)
+          LHSV = InsertNewInstBefore(new CastInst(LHSV, NewTy,
+                                                  LHSV->getName()), I);
+        if (RHSV->getType() != NewTy)
+          RHSV = InsertNewInstBefore(new CastInst(RHSV, NewTy,
+                                                  RHSV->getName()), I);
+        return new SetCondInst(Cond, LHSV, RHSV);
       }
     }