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

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.348 -> 1.349
---
Log message:

Fix PR577: http://llvm.cs.uiuc.edu/PR577  and testcase InstCombine/2005-06-15-ShiftSetCCCrash.ll.
Do not perform undefined out of range shifts.


---
Diffs of the changes:  (+16 -2)

 InstructionCombining.cpp |   18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)


Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.348 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.349
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.348	Wed Jun 15 13:25:30 2005
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Wed Jun 15 15:53:31 2005
@@ -2560,6 +2560,14 @@
           default: break;
           case Instruction::SetEQ:
           case Instruction::SetNE: {
+            unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
+
+            // Check that the shift amount is in range.  If not, don't perform
+            // undefined shifts.  When the shift is visited it will be
+            // simplified.
+            if (ShAmt->getValue() >= TypeBits)
+              break;
+
             // If we are comparing against bits always shifted out, the
             // comparison cannot succeed.
             Constant *Comp =
@@ -2573,7 +2581,6 @@
             if (LHSI->hasOneUse()) {
               // Otherwise strength reduce the shift into an and.
               unsigned ShAmtVal = (unsigned)ShAmt->getValue();
-              unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
               uint64_t Val = (1ULL << (TypeBits-ShAmtVal))-1;
 
               Constant *Mask;
@@ -2603,6 +2610,14 @@
           default: break;
           case Instruction::SetEQ:
           case Instruction::SetNE: {
+
+            // Check that the shift amount is in range.  If not, don't perform
+            // undefined shifts.  When the shift is visited it will be
+            // simplified.
+            unsigned TypeBits = ShAmt->getType()->getPrimitiveSizeInBits();
+            if (ShAmt->getValue() >= TypeBits)
+              break;
+
             // If we are comparing against bits always shifted out, the
             // comparison cannot succeed.
             Constant *Comp =
@@ -2623,7 +2638,6 @@
 
               Constant *Mask;
               if (CI->getType()->isUnsigned()) {
-                unsigned TypeBits = CI->getType()->getPrimitiveSizeInBits();
                 Val &= ~0ULL >> (64-TypeBits);
                 Mask = ConstantUInt::get(CI->getType(), Val);
               } else {