Use a WeakVH for UnknownInstructions in AliasSetTracker
Summary:
This change solves the same problem as D30726, except that this only
throws out the bathwater.
AST was not correctly tracking and deleting UnknownInstructions via
handles. The existing code only tracks "pointers" in its
`ASTCallbackVH`, so an UnknownInstruction (that isn't also def'ing a
pointer used by another memory instruction) never gets a
`ASTCallbackVH`.
There are two other ways to solve this problem:
- Use the `PointerRec` scheme for both known and unknown instructions.
- Use a `CallbackVH` that erases the offending Instruction from the
UnknownInstruction list.
Both of the above changes seemed to be significantly (and unnecessarily
IMO) more complex than this.
Reviewers: chandlerc, dberlin, hfinkel, reames
Subscribers: mcrosier, llvm-commits
Differential Revision: https://reviews.llvm.org/D30849
llvm-svn: 297539
diff --git a/llvm/lib/Analysis/AliasSetTracker.cpp b/llvm/lib/Analysis/AliasSetTracker.cpp
index 701b0e1..16b711a 100644
--- a/llvm/lib/Analysis/AliasSetTracker.cpp
+++ b/llvm/lib/Analysis/AliasSetTracker.cpp
@@ -199,9 +199,10 @@
// Check the unknown instructions...
if (!UnknownInsts.empty()) {
for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i)
- if (AA.getModRefInfo(UnknownInsts[i],
- MemoryLocation(Ptr, Size, AAInfo)) != MRI_NoModRef)
- return true;
+ if (auto *Inst = getUnknownInst(i))
+ if (AA.getModRefInfo(Inst, MemoryLocation(Ptr, Size, AAInfo)) !=
+ MRI_NoModRef)
+ return true;
}
return false;
@@ -217,10 +218,12 @@
return false;
for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
- ImmutableCallSite C1(getUnknownInst(i)), C2(Inst);
- if (!C1 || !C2 || AA.getModRefInfo(C1, C2) != MRI_NoModRef ||
- AA.getModRefInfo(C2, C1) != MRI_NoModRef)
- return true;
+ if (auto *Inst = getUnknownInst(i)) {
+ ImmutableCallSite C1(Inst), C2(Inst);
+ if (!C1 || !C2 || AA.getModRefInfo(C1, C2) != MRI_NoModRef ||
+ AA.getModRefInfo(C2, C1) != MRI_NoModRef)
+ return true;
+ }
}
for (iterator I = begin(), E = end(); I != E; ++I)
@@ -471,7 +474,8 @@
// If there are any call sites in the alias set, add them to this AST.
for (unsigned i = 0, e = AS.UnknownInsts.size(); i != e; ++i)
- add(AS.UnknownInsts[i]);
+ if (auto *Inst = AS.getUnknownInst(i))
+ add(Inst);
// Loop over all of the pointers in this alias set.
for (AliasSet::iterator ASI = AS.begin(), E = AS.end(); ASI != E; ++ASI) {
@@ -489,19 +493,6 @@
// dangling pointers to deleted instructions.
//
void AliasSetTracker::deleteValue(Value *PtrVal) {
- // If this is a call instruction, remove the callsite from the appropriate
- // AliasSet (if present).
- if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
- if (Inst->mayReadOrWriteMemory()) {
- // Scan all the alias sets to see if this call site is contained.
- for (iterator I = begin(), E = end(); I != E;) {
- iterator Cur = I++;
- if (!Cur->Forward)
- Cur->removeUnknownInst(*this, Inst);
- }
- }
- }
-
// First, look up the PointerRec for this pointer.
PointerMapType::iterator I = PointerMap.find_as(PtrVal);
if (I == PointerMap.end()) return; // Noop
@@ -633,7 +624,8 @@
OS << "\n " << UnknownInsts.size() << " Unknown instructions: ";
for (unsigned i = 0, e = UnknownInsts.size(); i != e; ++i) {
if (i) OS << ", ";
- UnknownInsts[i]->printAsOperand(OS);
+ if (auto *I = getUnknownInst(i))
+ I->printAsOperand(OS);
}
}
OS << "\n";