diff options
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/Scalar/GVN.cpp | 25 |
1 files changed, 21 insertions, 4 deletions
diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp index 6f74108b55..a6cc9931ef 100644 --- a/lib/Transforms/Scalar/GVN.cpp +++ b/lib/Transforms/Scalar/GVN.cpp @@ -508,7 +508,7 @@ uint32_t ValueTable::lookup_or_add(Value* V) { } else if (Instruction *NonLocalDepInst = I->second.getInst()) { // FIXME: INDENT PROPERLY // FIXME: All duplicated with non-local case. - if (DT->properlyDominates(I->first, C->getParent())) { + if (cdep == 0 && DT->properlyDominates(I->first, C->getParent())) { if (CallInst* CD = dyn_cast<CallInst>(NonLocalDepInst)) cdep = CD; else { @@ -527,6 +527,12 @@ uint32_t ValueTable::lookup_or_add(Value* V) { return nextValueNumber++; } + // FIXME: THIS ISN'T SAFE: CONSIDER: + // X = strlen(str) + // if (C) + // str[0] = 1; + // Y = strlen(str) + // This doesn't guarantee all-paths availability! if (cdep->getCalledFunction() != C->getCalledFunction() || cdep->getNumOperands() != C->getNumOperands()) { valueNumbering.insert(std::make_pair(V, nextValueNumber)); @@ -874,16 +880,27 @@ bool GVN::processNonLocalLoad(LoadInst* L, if (deps.size() > 100) return false; + BasicBlock *EntryBlock = &L->getParent()->getParent()->getEntryBlock(); + DenseMap<BasicBlock*, Value*> repl; // Filter out useless results (non-locals, etc) for (DenseMap<BasicBlock*, MemDepResult>::iterator I = deps.begin(), E = deps.end(); I != E; ++I) { - if (I->second.isNone()) - return false; + if (I->second.isNone()) { + repl[I->first] = UndefValue::get(L->getType()); + continue; + } - if (I->second.isNonLocal()) + if (I->second.isNonLocal()) { + // If this is a non-local dependency in the entry block, then we depend on + // the value live-in at the start of the function. We could insert a load + // in the entry block to get this, but for now we'll just bail out. + // FIXME: Consider emitting a load in the entry block to catch this case! + if (I->first == EntryBlock) + return false; continue; + } if (StoreInst* S = dyn_cast<StoreInst>(I->second.getInst())) { if (S->getPointerOperand() != L->getPointerOperand()) |