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recommit r172363 & r171325 (reverted in r172756)

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This adds minimalistic support for PHI nodes to llvm.objectsize() evaluation

fingers crossed so that it does break clang boostrap again..

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176408 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nuno Lopes
2013-03-02 11:36:24 +00:00
parent 2bc689c846
commit b443a0aeac
3 changed files with 160 additions and 13 deletions
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41
lib/Analysis/MemoryBuiltins.cpp
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@ -405,16 +405,23 @@ ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout *TD,
SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
V = V->stripPointerCasts();
if (Instruction *I = dyn_cast<Instruction>(V)) {
// If we have already seen this instruction, bail out. Cycles can happen in
// unreachable code after constant propagation.
if (!SeenInsts.insert(I))
return unknown();
if (isa<Instruction>(V) || isa<GEPOperator>(V)) {
// Return cached value or insert unknown in cache if size of V was not
// computed yet in order to avoid recursions in PHis.
std::pair<CacheMapTy::iterator, bool> CacheVal =
CacheMap.insert(std::make_pair(V, unknown()));
if (!CacheVal.second)
return CacheVal.first->second;
SizeOffsetType Result;
if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
return visitGEPOperator(*GEP);
return visit(*I);
Result = visitGEPOperator(*GEP);
else
Result = visit(cast<Instruction>(*V));
return CacheMap[V] = Result;
}
if (Argument *A = dyn_cast<Argument>(V))
return visitArgument(*A);
if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
@ -428,8 +435,6 @@ SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() == Instruction::IntToPtr)
return unknown(); // clueless
if (CE->getOpcode() == Instruction::GetElementPtr)
return visitGEPOperator(cast<GEPOperator>(*CE));
}
DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V
@ -563,9 +568,21 @@ SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) {
return unknown();
}
SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) {
// too complex to analyze statically.
return unknown();
SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode &PHI) {
if (PHI.getNumIncomingValues() == 0)
return unknown();
SizeOffsetType Ret = compute(PHI.getIncomingValue(0));
if (!bothKnown(Ret))
return unknown();
// Verify that all PHI incoming pointers have the same size and offset.
for (unsigned i = 1, e = PHI.getNumIncomingValues(); i != e; ++i) {
SizeOffsetType EdgeData = compute(PHI.getIncomingValue(i));
if (!bothKnown(EdgeData) || EdgeData != Ret)
return unknown();
}
return Ret;
}
SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {