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

[Devang Patel]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.520 -> 1.521
---
Log message:

Fix bug in PR454: http://llvm.org/PR454  resolution. Added new test case.
This fixes llvmAsmParser.cpp miscompile by llvm on PowerPC Darwin.


---
Diffs of the changes:  (+15 -1)

 InstructionCombining.cpp |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletion(-)


Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.520 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.521
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.520	Mon Oct 16 18:08:08 2006
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Thu Oct 19 13:54:08 2006
@@ -4785,7 +4785,21 @@
     Constant *Res = ConstantExpr::getCast(CI, SrcTy);
 
     if (ConstantExpr::getCast(Res, DestTy) == CI) {
-      RHSCIOp = Res;
+      // Make sure that src sign and dest sign match. For example,
+      //
+      // %A = cast short %X to uint
+      // %B = setgt uint %A, 1330
+      //
+      // It is incorrect to transformt this into 
+      //
+      // %B = setgt short %X, 1330 
+      // 
+      // because %A may have negative value. 
+      // However, it is OK if SrcTy is bool. See cast-set.ll testcase.
+      if (isSignSrc == isSignDest || SrcTy == Type::BoolTy)
+        RHSCIOp = Res;
+      else
+        return 0;
     } else {
       // If the value cannot be represented in the shorter type, we cannot emit
       // a simple comparison.