Changes in directory llvm/lib/Transforms/Scalar:
InstructionCombining.cpp updated: 1.433 -> 1.434
---
Log message:
If any of the sign extended bits are demanded, the input sign bit is demanded
for a sign extension.
This fixes InstCombine/2006-02-13-DemandedMiscompile.ll and Ptrdist/bc.
---
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:1.433
llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.434
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.433 Mon Feb 13
00:09:08 2006
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp Mon Feb 13 16:41:07 2006
@@ -889,15 +889,21 @@
KnownZero |= NewBits;
} else {
// Sign extension.
- if (SimplifyDemandedBits(I->getOperand(0),
- DemandedMask & SrcTy->getIntegralTypeMask(),
+ uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1);
+ int64_t InputDemandedBits = DemandedMask & SrcTy->getIntegralTypeMask();
+
+ // If any of the sign extended bits are demanded, we know that the sign
+ // bit is demanded.
+ if (NewBits & DemandedMask)
+ InputDemandedBits |= InSignBit;
+
+ if (SimplifyDemandedBits(I->getOperand(0), InputDemandedBits,
KnownZero, KnownOne, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
// If the sign bit of the input is known set or clear, then we know the
// top bits of the result.
- uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1);
// If the input sign bit is known zero, or if the NewBits are not
demanded
// convert this into a zero extension.
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