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Fix a regression for r259736.

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When SCEV expansion tries to reuse an existing value, it is needed to ensure
that using the Value at the InsertPt will not break LCSSA. The fix adds a
check that InsertPt is either inside the candidate Value's parent loop, or
the candidate Value's parent loop is nullptr.

llvm-svn: 259815
This commit is contained in:
Wei Mi 2016-02-04 19:17:33 +00:00
parent 4d03873f9c
commit 09f022feb9
1 changed files with 10 additions and 3 deletions
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13
lib/Analysis/ScalarEvolutionExpander.cpp
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@ -1652,10 +1652,17 @@ Value *SCEVExpander::expand(const SCEV *S) {
// If S is scConstant, it may be worse to reuse an existing Value.
if (S->getSCEVType() != scConstant && Set) {
// Choose a Value from the set which dominates the insertPt.
// insertPt should be inside the Value's parent loop so as not to break
// the LCSSA form.
for (auto const &Ent : *Set) {
if (Ent && isa<Instruction>(Ent) && S->getType() == Ent->getType() &&
cast<Instruction>(Ent)->getFunction() == InsertPt->getFunction() &&
SE.DT.dominates(cast<Instruction>(Ent), InsertPt)) {
Instruction *EntInst = nullptr;
if (Ent && isa<Instruction>(Ent) &&
(EntInst = cast<Instruction>(Ent)) &&
S->getType() == Ent->getType() &&
EntInst->getFunction() == InsertPt->getFunction() &&
SE.DT.dominates(EntInst, InsertPt) &&
(SE.LI.getLoopFor(EntInst->getParent()) == nullptr ||
SE.LI.getLoopFor(EntInst->getParent())->contains(InsertPt))) {
V = Ent;
break;
}