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Make some intrinsics safe to speculatively execute.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147036 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky
2011-12-21 05:52:02 +00:00
parent 1e33e8b715
commit 8369687576
3 changed files with 53 additions and 7 deletions
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28
lib/Analysis/ValueTracking.cpp
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@@ -1912,11 +1912,31 @@ bool llvm::isSafeToSpeculativelyExecute(const Instruction *Inst,
return false;
return LI->getPointerOperand()->isDereferenceablePointer();
}
case Instruction::Call:
case Instruction::Call: {
if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
switch (II->getIntrinsicID()) {
case Intrinsic::bswap:
case Intrinsic::ctlz:
case Intrinsic::ctpop:
case Intrinsic::cttz:
case Intrinsic::objectsize:
case Intrinsic::sadd_with_overflow:
case Intrinsic::smul_with_overflow:
case Intrinsic::ssub_with_overflow:
case Intrinsic::uadd_with_overflow:
case Intrinsic::umul_with_overflow:
case Intrinsic::usub_with_overflow:
return true;
// TODO: some fp intrinsics are marked as having the same error handling
// as libm. They're safe to speculate when they won't error.
// TODO: are convert_{from,to}_fp16 safe?
// TODO: can we list target-specific intrinsics here?
default: break;
}
}
return false; // The called function could have undefined behavior or
// side-effects.
// FIXME: We should special-case some intrinsics (bswap,
// overflow-checking arithmetic, etc.)
// side-effects, even if marked readnone nounwind.
}
case Instruction::VAArg:
case Instruction::Alloca:
case Instruction::Invoke: