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When ScalarEvolution is told to forget the trip count for a loop, have

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it also forget any SCEVs associated with loop-header PHIs in the loop,
as they may be dependent on trip count information.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70633 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2009-05-02 17:43:35 +00:00
parent 9a936502fa
commit fb7d35f22a
2 changed files with 16 additions and 3 deletions
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5
include/llvm/Analysis/ScalarEvolution.h
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@ -333,6 +333,11 @@ namespace llvm {
/// expression cannot be evaluated, return UnknownValue itself. /// expression cannot be evaluated, return UnknownValue itself.
SCEVHandle getSCEVAtScope(SCEV *S, const Loop *L); SCEVHandle getSCEVAtScope(SCEV *S, const Loop *L);
/// forgetLoopPHIs - Delete the memoized SCEVs associated with the
/// PHI nodes in the given loop. This is used when the trip count of
/// the loop may have changed.
void forgetLoopPHIs(const Loop *L);
public: public:
static char ID; // Pass identification, replacement for typeid static char ID; // Pass identification, replacement for typeid
ScalarEvolution(); ScalarEvolution();

14
lib/Analysis/ScalarEvolution.cpp
View File

@ -2111,9 +2111,7 @@ ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
// conservative estimates made without the benefit // conservative estimates made without the benefit
// of trip count information. // of trip count information.
if (ItCount.hasAnyInfo()) if (ItCount.hasAnyInfo())
for (BasicBlock::iterator I = L->getHeader()->begin(); forgetLoopPHIs(L);
PHINode *PN = dyn_cast<PHINode>(I); ++I)
deleteValueFromRecords(PN);
} }
return Pair.first->second; return Pair.first->second;
} }
@ -2124,6 +2122,16 @@ ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
/// is deleted. /// is deleted.
void ScalarEvolution::forgetLoopBackedgeTakenCount(const Loop *L) { void ScalarEvolution::forgetLoopBackedgeTakenCount(const Loop *L) {
BackedgeTakenCounts.erase(L); BackedgeTakenCounts.erase(L);
forgetLoopPHIs(L);
}
/// forgetLoopPHIs - Delete the memoized SCEVs associated with the
/// PHI nodes in the given loop. This is used when the trip count of
/// the loop may have changed.
void ScalarEvolution::forgetLoopPHIs(const Loop *L) {
for (BasicBlock::iterator I = L->getHeader()->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I)
deleteValueFromRecords(PN);
} }
/// ComputeBackedgeTakenCount - Compute the number of times the backedge /// ComputeBackedgeTakenCount - Compute the number of times the backedge