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[MemorySSA] Relax verification of clobbering accesses. 

llvm-svn: 341733
This commit is contained in:
Alina Sbirlea 2018-09-07 23:51:41 +00:00
parent fc89d18bb1
commit 65f385da63
1 changed files with 12 additions and 2 deletions
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14
llvm/lib/Analysis/MemorySSA.cpp
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@ -380,10 +380,12 @@ static bool isUseTriviallyOptimizableToLiveOnEntry(AliasAnalysis &AA,
/// \param MSSA The MemorySSA instance that Start and ClobberAt belong to. /// \param MSSA The MemorySSA instance that Start and ClobberAt belong to.
/// \param Query The UpwardsMemoryQuery we used for our search. /// \param Query The UpwardsMemoryQuery we used for our search.
/// \param AA The AliasAnalysis we used for our search. /// \param AA The AliasAnalysis we used for our search.
/// \param AllowImpreciseClobber Always false, unless we do relaxed verify.
static void static void
checkClobberSanity(const MemoryAccess *Start, MemoryAccess *ClobberAt, checkClobberSanity(const MemoryAccess *Start, MemoryAccess *ClobberAt,
const MemoryLocation &StartLoc, const MemorySSA &MSSA, const MemoryLocation &StartLoc, const MemorySSA &MSSA,
const UpwardsMemoryQuery &Query, AliasAnalysis &AA) { const UpwardsMemoryQuery &Query, AliasAnalysis &AA,
bool AllowImpreciseClobber = false) {
assert(MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?"); assert(MSSA.dominates(ClobberAt, Start) && "Clobber doesn't dominate start?");
if (MSSA.isLiveOnEntryDef(Start)) { if (MSSA.isLiveOnEntryDef(Start)) {
@ -454,6 +456,14 @@ checkClobberSanity(const MemoryAccess *Start, MemoryAccess *ClobberAt,
} }
} }
// If the verify is done following an optimization, it's possible that
// ClobberAt was a conservative clobbering, that we can now infer is not a
// true clobbering access. Don't fail the verify if that's the case.
// We do have accesses that claim they're optimized, but could be optimized
// further. Updating all these can be expensive, so allow it for now (FIXME).
if (AllowImpreciseClobber)
return;
// If ClobberAt is a MemoryPhi, we can assume something above it acted as a // If ClobberAt is a MemoryPhi, we can assume something above it acted as a
// clobber. Otherwise, `ClobberAt` should've acted as a clobber at some point. // clobber. Otherwise, `ClobberAt` should've acted as a clobber at some point.
assert((isa<MemoryPhi>(ClobberAt) || FoundClobber) && assert((isa<MemoryPhi>(ClobberAt) || FoundClobber) &&
@ -1694,7 +1704,7 @@ void MemorySSA::checkClobberSanityAccess(const MemoryAccess *MA) const {
return; return;
auto *Clobber = MUD->getOptimized(); auto *Clobber = MUD->getOptimized();
UpwardsMemoryQuery Q(I, MUD); UpwardsMemoryQuery Q(I, MUD);
checkClobberSanity(MUD, Clobber, *Loc, *this, Q, *AA); checkClobberSanity(MUD, Clobber, *Loc, *this, Q, *AA, true);
} }
} }