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

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.352 -> 1.353
---
Log message:

avoid constructing out of range shift amounts.


---
Diffs of the changes:  (+4 -2)

 InstructionCombining.cpp |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)


Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.352 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.353
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.352	Wed Jun 15 23:55:52 2005
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Thu Jun 16 20:29:28 2005
@@ -2511,8 +2511,10 @@
             if (!CanFold) {
               // To test for the bad case of the signed shr, see if any
               // of the bits shifted in could be tested after the mask.
-              Constant *OShAmt = ConstantUInt::get(Type::UByteTy,
-                               Ty->getPrimitiveSizeInBits()-ShAmt->getValue());
+              int ShAmtVal = Ty->getPrimitiveSizeInBits()-ShAmt->getValue();
+              if (ShAmtVal < 0) ShAmtVal = 0; // Out of range shift.
+
+              Constant *OShAmt = ConstantUInt::get(Type::UByteTy, ShAmtVal);
               Constant *ShVal =
                 ConstantExpr::getShl(ConstantInt::getAllOnesValue(Ty), OShAmt);
               if (ConstantExpr::getAnd(ShVal, AndCST)->isNullValue())