/// Tracks instructions visited by pointsToConstantMemory.
SmallPtrSet<const Value *, 16> Visited;
+ /// Whether to disable persistent caching in AAQI. This is used to prevent
+ /// caching of results based on temporary assumptions.
+ bool DisableCache = false;
+
static const Value *
GetLinearExpression(const Value *V, APInt &Scale, APInt &Offset,
unsigned &ZExtBits, unsigned &SExtBits,
LocationSize V2Size, const AAMDNodes &V2AATag,
AAQueryInfo &AAQI, const Value *O1 = nullptr,
const Value *O2 = nullptr);
+
+ AliasResult aliasCheckRecursive(const Value *V1, LocationSize V1Size,
+ const AAMDNodes &V1AATag, const Value *V2,
+ LocationSize V2Size, const AAMDNodes &V2AATag,
+ AAQueryInfo &AAQI, const Value *O1,
+ const Value *O2);
};
/// Analysis pass providing a never-invalidated alias analysis result.
// operand from outside the PHIs' cycle that is MayAlias/MustAlias or
// there must be an operation on the PHIs within the PHIs' value cycle
// that causes a MayAlias.
- // Pretend the phis do not alias.
- AliasResult Alias = NoAlias;
+ // Disable persistent caching, so intermediate results based on a
+ // possibly incorrect assumption do not get cached.
+ bool OrigDisableCache = DisableCache;
+ DisableCache = true;
AliasResult OrigAliasResult;
{
// Limited lifetime iterator invalidated by the aliasCheck call below.
CacheIt->second = NoAlias;
}
+ AliasResult Alias = NoAlias;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
AliasResult ThisAlias =
aliasCheck(PN->getIncomingValue(i), PNSize, PNAAInfo,
// Reset if speculation failed.
if (Alias != NoAlias)
AAQI.updateResult(Locs, OrigAliasResult);
+ DisableCache = OrigDisableCache;
return Alias;
}
if (!Pair.second)
return Pair.first->second;
+ AliasResult Result = aliasCheckRecursive(V1, V1Size, V1AAInfo, V2, V2Size,
+ V2AAInfo, AAQI, O1, O2);
+
+ // If caching is disabled, remove the entry once the recursive checks are
+ // done. We only needed it to prevent infinite recursion.
+ if (DisableCache)
+ AAQI.AliasCache.erase(AAQI.AliasCache.find(Locs));
+ else if (Result != MayAlias)
+ AAQI.updateResult(Locs, Result);
+ return Result;
+}
+
+AliasResult BasicAAResult::aliasCheckRecursive(
+ const Value *V1, LocationSize V1Size, const AAMDNodes &V1AAInfo,
+ const Value *V2, LocationSize V2Size, const AAMDNodes &V2AAInfo,
+ AAQueryInfo &AAQI, const Value *O1, const Value *O2) {
if (const GEPOperator *GV1 = dyn_cast<GEPOperator>(V1)) {
AliasResult Result =
aliasGEP(GV1, V1Size, V1AAInfo, V2, V2Size, V2AAInfo, O1, O2, AAQI);
if (Result != MayAlias)
- return AAQI.updateResult(Locs, Result);
+ return Result;
} else if (const GEPOperator *GV2 = dyn_cast<GEPOperator>(V2)) {
AliasResult Result =
aliasGEP(GV2, V2Size, V2AAInfo, V1, V1Size, V1AAInfo, O2, O1, AAQI);
if (Result != MayAlias)
- return AAQI.updateResult(Locs, Result);
+ return Result;
}
if (const PHINode *PN = dyn_cast<PHINode>(V1)) {
AliasResult Result =
aliasPHI(PN, V1Size, V1AAInfo, V2, V2Size, V2AAInfo, O2, AAQI);
if (Result != MayAlias)
- return AAQI.updateResult(Locs, Result);
+ return Result;
} else if (const PHINode *PN = dyn_cast<PHINode>(V2)) {
AliasResult Result =
aliasPHI(PN, V2Size, V2AAInfo, V1, V1Size, V1AAInfo, O1, AAQI);
if (Result != MayAlias)
- return AAQI.updateResult(Locs, Result);
+ return Result;
}
if (const SelectInst *S1 = dyn_cast<SelectInst>(V1)) {
AliasResult Result =
aliasSelect(S1, V1Size, V1AAInfo, V2, V2Size, V2AAInfo, O2, AAQI);
if (Result != MayAlias)
- return AAQI.updateResult(Locs, Result);
+ return Result;
} else if (const SelectInst *S2 = dyn_cast<SelectInst>(V2)) {
AliasResult Result =
aliasSelect(S2, V2Size, V2AAInfo, V1, V1Size, V1AAInfo, O1, AAQI);
if (Result != MayAlias)
- return AAQI.updateResult(Locs, Result);
+ return Result;
}
// If both pointers are pointing into the same object and one of them
// accesses the entire object, then the accesses must overlap in some way.
- if (O1 == O2)
+ if (O1 == O2) {
+ bool NullIsValidLocation = NullPointerIsDefined(&F);
if (V1Size.isPrecise() && V2Size.isPrecise() &&
(isObjectSize(O1, V1Size.getValue(), DL, TLI, NullIsValidLocation) ||
isObjectSize(O2, V2Size.getValue(), DL, TLI, NullIsValidLocation)))
- return AAQI.updateResult(Locs, PartialAlias);
+ return 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, AAQI);
- if (Result != MayAlias)
- return AAQI.updateResult(Locs, Result);
-
- // MayAlias is already in the cache.
- return MayAlias;
+ return getBestAAResults().alias(MemoryLocation(V1, V1Size, V1AAInfo),
+ MemoryLocation(V2, V2Size, V2AAInfo), AAQI);
}
/// Check whether two Values can be considered equivalent.