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Refactor isValidAssumeForContext to reduce duplication and indentation. NFC.

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This method had some duplicate code when we did or did not have a dom tree.  Refactor
it to remove the duplication, but also clean up the control flow to have less duplication.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278450 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Pete Cooper 2016-08-12 01:00:15 +00:00
parent b0353c6db2
commit 2d34392ce2
1 changed files with 22 additions and 28 deletions
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50
lib/Analysis/ValueTracking.cpp
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@ -468,45 +468,39 @@ bool llvm::isValidAssumeForContext(const Instruction *Inv,
// the assume).
if (DT) {
if (DT->dominates(Inv, CxtI)) {
if (DT->dominates(Inv, CxtI))
return true;
} else if (Inv->getParent() == CxtI->getParent()) {
// The context comes first, but they're both in the same block. Make sure
// there is nothing in between that might interrupt the control flow.
for (BasicBlock::const_iterator I =
std::next(BasicBlock::const_iterator(CxtI)),
IE(Inv); I != IE; ++I)
if (!isSafeToSpeculativelyExecute(&*I) && !isAssumeLikeIntrinsic(&*I))
return false;
return !isEphemeralValueOf(Inv, CxtI);
}
return false;
} else if (Inv->getParent() == CxtI->getParent()->getSinglePredecessor()) {
// We don't have a DT, but this trivially dominates.
return true;
}
// When we don't have a DT, we do a limited search...
if (Inv->getParent() == CxtI->getParent()->getSinglePredecessor()) {
return true;
} else if (Inv->getParent() == CxtI->getParent()) {
// With or without a DT, the only remaining case we will check is if the
// instructions are in the same BB. Give up if that is not the case.
if (Inv->getParent() != CxtI->getParent())
return false;
// If we have a dom tree, then we now know that the assume doens't dominate
// the other instruction. If we don't have a dom tree then we can check if
// the assume is first in the BB.
if (!DT) {
// Search forward from the assume until we reach the context (or the end
// of the block); the common case is that the assume will come first.
for (auto I = std::next(BasicBlock::const_iterator(Inv)),
IE = Inv->getParent()->end(); I != IE; ++I)
if (&*I == CxtI)
return true;
// The context must come first...
for (BasicBlock::const_iterator I =
std::next(BasicBlock::const_iterator(CxtI)),
IE(Inv); I != IE; ++I)
if (!isSafeToSpeculativelyExecute(&*I) && !isAssumeLikeIntrinsic(&*I))
return false;
return !isEphemeralValueOf(Inv, CxtI);
}
return false;
// The context comes first, but they're both in the same block. Make sure
// there is nothing in between that might interrupt the control flow.
for (BasicBlock::const_iterator I =
std::next(BasicBlock::const_iterator(CxtI)), IE(Inv);
I != IE; ++I)
if (!isSafeToSpeculativelyExecute(&*I) && !isAssumeLikeIntrinsic(&*I))
return false;
return !isEphemeralValueOf(Inv, CxtI);
}
static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,