recommit r172363 & r171325 (reverted in r172756)
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
diff --git a/lib/Analysis/MemoryBuiltins.cpp b/lib/Analysis/MemoryBuiltins.cpp
index 90f5811..bd7758f 100644
--- a/lib/Analysis/MemoryBuiltins.cpp
+++ b/lib/Analysis/MemoryBuiltins.cpp
@@ -405,16 +405,23 @@
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 @@
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 @@
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) {