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[Refactor] Have getNonLocalPointerDependency take the query instruction

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Previously, MemoryDependenceAnalysis::getNonLocalPointerDependency was taking a list of properties about the instruction being queried. Since I'm about to need one more property to be passed down through the infrastructure - I need to know a query instruction is non-volatile in an inner helper - fix the interface once and for all.

I also added some assertions and behaviour clarifications around volatile and ordered field accesses. At the moment, this is mostly to document expected behaviour. The only non-standard instructions which can currently reach this are atomic, but unordered, loads and stores. Neither ordered or volatile accesses can reach here.

The call in GVN is protected by an isSimple check when it first considers the load. The calls in MemDepPrinter are protected by isUnordered checks. Both utilities also check isVolatile for loads and stores.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225481 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Philip Reames
2015-01-09 00:04:22 +00:00
parent cce3a8acec
commit dba2d12578
4 changed files with 56 additions and 16 deletions
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48
lib/Analysis/MemoryDependenceAnalysis.cpp
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@ -859,9 +859,53 @@ MemoryDependenceAnalysis::getNonLocalCallDependency(CallSite QueryCS) {
/// own block.
///
void MemoryDependenceAnalysis::
getNonLocalPointerDependency(const AliasAnalysis::Location &Loc, bool isLoad,
BasicBlock *FromBB,
getNonLocalPointerDependency(Instruction *QueryInst,
SmallVectorImpl<NonLocalDepResult> &Result) {
auto getLocation = [](AliasAnalysis *AA, Instruction *Inst) {
if (auto *I = dyn_cast<LoadInst>(Inst))
return AA->getLocation(I);
else if (auto *I = dyn_cast<StoreInst>(Inst))
return AA->getLocation(I);
else if (auto *I = dyn_cast<VAArgInst>(Inst))
return AA->getLocation(I);
else if (auto *I = dyn_cast<AtomicCmpXchgInst>(Inst))
return AA->getLocation(I);
else if (auto *I = dyn_cast<AtomicRMWInst>(Inst))
return AA->getLocation(I);
else
llvm_unreachable("unsupported memory instruction");
};
const AliasAnalysis::Location Loc = getLocation(AA, QueryInst);
bool isLoad = isa<LoadInst>(QueryInst);
BasicBlock *FromBB = QueryInst->getParent();
assert(FromBB);
// This routine does not expect to deal with volatile instructions. Doing so
// would require piping through the QueryInst all the way through.
// TODO: volatiles can't be elided, but they can be reordered with other
// non-volatile accesses.
if (LoadInst *LI = dyn_cast<LoadInst>(QueryInst)) {
assert(!LI->isVolatile());
} else if (StoreInst *SI = dyn_cast<StoreInst>(QueryInst)) {
assert(!SI->isVolatile());
}
// We currently give up on any instruction which is ordered, but we do handle
// atomic instructions which are unordered.
// TODO: Handle ordered instructions
auto isOrdered = [](Instruction *Inst) {
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
return !LI->isUnordered();
} else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
return !SI->isUnordered();
}
return false;
};
assert(!isOrdered(QueryInst) && "ordered instructions not expected");
assert(Loc.Ptr->getType()->isPointerTy() &&
"Can't get pointer deps of a non-pointer!");
Result.clear();