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[BasicAA] Reduce no of map seaches [NFCI].

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Summary:
This is a refactoring patch.
- Reduce the number of map searches by reusing the iterator.
- Add asserts to check that the entry is in the cache, as this is something BasicAA relies on to avoid infinite recursion.

Reviewers: chandlerc, aschwaighofer

Subscribers: sanjoy, jlebar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59151

llvm-svn: 356644
This commit is contained in:
Alina Sbirlea 2019-03-21 05:02:05 +00:00
parent aa1e617c6b
commit cc7694fc25
1 changed files with 32 additions and 14 deletions
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46
lib/Analysis/BasicAliasAnalysis.cpp
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@ -1585,10 +1585,15 @@ AliasResult BasicAAResult::aliasPHI(const PHINode *PN, LocationSize PNSize,
// that causes a MayAlias.
// Pretend the phis do not alias.
AliasResult Alias = NoAlias;
assert(AliasCache.count(Locs) &&
"There must exist an entry for the phi node");
AliasResult OrigAliasResult = AliasCache[Locs];
AliasCache[Locs] = NoAlias;
AliasResult OrigAliasResult;
{
// Limited lifetime iterator invalidated by the aliasCheck call below.
auto CacheIt = AliasCache.find(Locs);
assert((CacheIt != AliasCache.end()) &&
"There must exist an entry for the phi node");
OrigAliasResult = CacheIt->second;
CacheIt->second = NoAlias;
}
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
AliasResult ThisAlias =
@ -1601,9 +1606,11 @@ AliasResult BasicAAResult::aliasPHI(const PHINode *PN, LocationSize PNSize,
}
// Reset if speculation failed.
if (Alias != NoAlias)
AliasCache[Locs] = OrigAliasResult;
if (Alias != NoAlias) {
auto Pair = AliasCache.insert(std::make_pair(Locs, OrigAliasResult));
assert(!Pair.second && "Entry must have existed");
Pair.first->second = OrigAliasResult;
}
return Alias;
}
@ -1824,8 +1831,11 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
if (const PHINode *PN = dyn_cast<PHINode>(V1)) {
AliasResult Result = aliasPHI(PN, V1Size, V1AAInfo,
V2, V2Size, V2AAInfo, O2);
if (Result != MayAlias)
return AliasCache[Locs] = Result;
if (Result != MayAlias) {
Pair = AliasCache.insert(std::make_pair(Locs, Result));
assert(!Pair.second && "Entry must have existed");
return Pair.first->second = Result;
}
}
if (isa<SelectInst>(V2) && !isa<SelectInst>(V1)) {
@ -1837,8 +1847,11 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
if (const SelectInst *S1 = dyn_cast<SelectInst>(V1)) {
AliasResult Result =
aliasSelect(S1, V1Size, V1AAInfo, V2, V2Size, V2AAInfo, O2);
if (Result != MayAlias)
return AliasCache[Locs] = Result;
if (Result != MayAlias) {
Pair = AliasCache.insert(std::make_pair(Locs, Result));
assert(!Pair.second && "Entry must have existed");
return Pair.first->second = Result;
}
}
// If both pointers are pointing into the same object and one of them
@ -1846,14 +1859,19 @@ AliasResult BasicAAResult::aliasCheck(const Value *V1, LocationSize V1Size,
if (O1 == O2)
if (V1Size.isPrecise() && V2Size.isPrecise() &&
(isObjectSize(O1, V1Size.getValue(), DL, TLI, NullIsValidLocation) ||
isObjectSize(O2, V2Size.getValue(), DL, TLI, NullIsValidLocation)))
return AliasCache[Locs] = PartialAlias;
isObjectSize(O2, V2Size.getValue(), DL, TLI, NullIsValidLocation))) {
Pair = AliasCache.insert(std::make_pair(Locs, PartialAlias));
assert(!Pair.second && "Entry must have existed");
return Pair.first->second = PartialAlias;
}
// Recurse back into the best AA results we have, potentially with refined
// memory locations. We have already ensured that BasicAA has a MayAlias
// cache result for these, so any recursion back into BasicAA won't loop.
AliasResult Result = getBestAAResults().alias(Locs.first, Locs.second);
return AliasCache[Locs] = Result;
Pair = AliasCache.insert(std::make_pair(Locs, Result));
assert(!Pair.second && "Entry must have existed");
return Pair.first->second = Result;
}
/// Check whether two Values can be considered equivalent.