[PhiValues] Use callback value handles to invalidate deleted values

The way that PhiValues is integrated with BasicAA it is possible for a pass
which uses BasicAA to pick up an instance of BasicAA that uses PhiValues without
intending to, and then delete values from a function in a way that causes
PhiValues to return dangling pointers to these deleted values. Fix this by
having a set of callback value handles to invalidate values when they're
deleted.

llvm-svn: 340613

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/PhiValues.cpp b/llvm/lib/Analysis/PhiValues.cpp
index ef121815d2c..729227c8669 100644
--- a/llvm/lib/Analysis/PhiValues.cpp
+++ b/llvm/lib/Analysis/PhiValues.cpp
@@ -14,6 +14,16 @@
 
 using namespace llvm;
 
+void PhiValues::PhiValuesCallbackVH::deleted() {
+  PV->invalidateValue(getValPtr());
+}
+
+void PhiValues::PhiValuesCallbackVH::allUsesReplacedWith(Value *) {
+  // We could potentially update the cached values we have with the new value,
+  // but it's simpler to just treat the old value as invalidated.
+  PV->invalidateValue(getValPtr());
+}
+
 bool PhiValues::invalidate(Function &, const PreservedAnalyses &PA,
                            FunctionAnalysisManager::Invalidator &) {
   // PhiValues is invalidated if it isn't preserved.
@@ -46,6 +56,7 @@ void PhiValues::processPhi(const PHINode *Phi,
   DepthMap[Phi] = DepthNumber;
 
   // Recursively process the incoming phis of this phi.
+  TrackedValues.insert(PhiValuesCallbackVH(const_cast<PHINode *>(Phi), this));
   for (Value *PhiOp : Phi->incoming_values()) {
     if (PHINode *PhiPhiOp = dyn_cast<PHINode>(PhiOp)) {
       // Recurse if the phi has not yet been visited.
@@ -56,6 +67,8 @@ void PhiValues::processPhi(const PHINode *Phi,
       // phi are part of the same component, so adjust the depth number.
       if (!ReachableMap.count(DepthMap[PhiPhiOp]))
         DepthMap[Phi] = std::min(DepthMap[Phi], DepthMap[PhiPhiOp]);
+    } else {
+      TrackedValues.insert(PhiValuesCallbackVH(PhiOp, this));
     }
   }
 
@@ -122,6 +135,10 @@ void PhiValues::invalidateValue(const Value *V) {
     NonPhiReachableMap.erase(N);
     ReachableMap.erase(N);
   }
+  // This value is no longer tracked
+  auto It = TrackedValues.find_as(V);
+  if (It != TrackedValues.end())
+    TrackedValues.erase(It);
 }
 
 void PhiValues::releaseMemory() {