6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-02-16 00:33:10 +00:00
Code Issues Projects Releases Wiki Activity

If any of the sign extended bits are demanded, the input sign bit is demanded

Browse Source 
for a sign extension.

This fixes InstCombine/2006-02-13-DemandedMiscompile.ll and Ptrdist/bc.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26152 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-02-13 22:41:07 +00:00
parent 3fcb664dbc
commit f345fe4d9a
1 changed files with 9 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -889,15 +889,21 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, uint64_t DemandedMask,
KnownZero |= NewBits; KnownZero |= NewBits;
} else { } else {
// Sign extension. // Sign extension.
if (SimplifyDemandedBits(I->getOperand(0), uint64_t InSignBit = 1ULL << (SrcTy->getPrimitiveSizeInBits()-1);
DemandedMask & SrcTy->getIntegralTypeMask(), 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)) KnownZero, KnownOne, Depth+1))
return true; return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 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 // If the sign bit of the input is known set or clear, then we know the
// top bits of the result. // 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 // If the input sign bit is known zero, or if the NewBits are not demanded
// convert this into a zero extension. // convert this into a zero extension.