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author | Martin Nowack <m.nowack@imperial.ac.uk> | 2018-07-29 16:49:48 +0100 |
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committer | Cristian Cadar <c.cadar@imperial.ac.uk> | 2018-10-24 14:15:25 +0300 |
commit | aba37b07e909b30636e06f33b456af3abaa8ed0e (patch) | |
tree | 217e05c3d9fdbc845fbad8b58e3c6a965dbf35f6 /lib/Module | |
parent | b90f6ad72e7991f3cebb892ff162645bb91168c8 (diff) | |
download | klee-aba37b07e909b30636e06f33b456af3abaa8ed0e.tar.gz |
ShiftChecker: Avoid unneeded checks
Do not instrument shift operations with constant shift operations that are smaller than the type size.
Diffstat (limited to 'lib/Module')
-rw-r--r-- | lib/Module/Checks.cpp | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/lib/Module/Checks.cpp b/lib/Module/Checks.cpp index bd9a8bd3..53ba4266 100644 --- a/lib/Module/Checks.cpp +++ b/lib/Module/Checks.cpp @@ -104,6 +104,16 @@ bool OvershiftCheckPass::runOnModule(Module &M) { if (opcode != Instruction::Shl && opcode != Instruction::LShr && opcode != Instruction::AShr) continue; + + // Check if the operand is constant and not zero, skip in that case + auto operand = binOp->getOperand(1); + if (auto coOp = dyn_cast<llvm::ConstantInt>(operand)) { + auto typeWidth = + binOp->getOperand(0)->getType()->getScalarSizeInBits(); + // If the constant shift is positive and smaller,equal the type width, + // we can ignore this instruction + if (!coOp->isNegative() && coOp->getZExtValue() < typeWidth) + continue; } shiftInstructions.push_back(binOp); |