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

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.432 -> 1.433
---
Log message:

Be careful not to request or look at bits shifted in from outside the size
of the input.  This fixes the mediabench/gsm/toast failure last night.


---
Diffs of the changes:  (+9 -3)

 InstructionCombining.cpp |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)


Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.432 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.433
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.432	Sun Feb 12 02:07:37 2006
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Mon Feb 13 00:09:08 2006
@@ -939,20 +939,26 @@
       // Compute the new bits that are at the top now.
       uint64_t HighBits = (1ULL << ShAmt)-1;
       HighBits <<= I->getType()->getPrimitiveSizeInBits() - ShAmt;
-      
+      uint64_t TypeMask = I->getType()->getIntegralTypeMask();
       if (I->getType()->isUnsigned()) {   // Unsigned shift right.
-        if (SimplifyDemandedBits(I->getOperand(0), DemandedMask << ShAmt, 
+        if (SimplifyDemandedBits(I->getOperand(0),
+                                 (DemandedMask << ShAmt) & TypeMask,
                                  KnownZero, KnownOne, Depth+1))
           return true;
         assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 
+        KnownZero &= TypeMask;
+        KnownOne  &= TypeMask;
         KnownZero >>= ShAmt;
         KnownOne  >>= ShAmt;
         KnownZero |= HighBits;  // high bits known zero.
       } else {                            // Signed shift right.
-        if (SimplifyDemandedBits(I->getOperand(0), DemandedMask << ShAmt,
+        if (SimplifyDemandedBits(I->getOperand(0),
+                                 (DemandedMask << ShAmt) & TypeMask,
                                  KnownZero, KnownOne, Depth+1))
           return true;
         assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 
+        KnownZero &= TypeMask;
+        KnownOne  &= TypeMask;
         KnownZero >>= SA->getValue();
         KnownOne  >>= SA->getValue();