Add a new AliassetTracker::remove method. Because we need to be able to remove
a pointer from an AliasSet, maintain the pointer values on a doubly linked
list instead of a singly linked list, to permit efficient removal from the
middle of the list.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10506 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/AliasSetTracker.cpp b/lib/Analysis/AliasSetTracker.cpp
index a3d58d9..67cef76 100644
--- a/lib/Analysis/AliasSetTracker.cpp
+++ b/lib/Analysis/AliasSetTracker.cpp
@@ -47,9 +47,14 @@
RefCount++; // AS is now pointing to us...
// Merge the list of constituent pointers...
- PtrListTail->second.setTail(AS.PtrListHead);
- PtrListTail = AS.PtrListTail;
- AS.PtrListHead = AS.PtrListTail = 0;
+ if (AS.PtrList) {
+ *PtrListEnd = AS.PtrList;
+ AS.PtrList->second.setPrevInList(PtrListEnd);
+ PtrListEnd = AS.PtrListEnd;
+
+ AS.PtrList = 0;
+ AS.PtrListEnd = &AS.PtrList;
+ }
}
void AliasSetTracker::removeAliasSet(AliasSet *AS) {
@@ -82,11 +87,9 @@
Entry.second.updateSize(Size);
// Add it to the end of the list...
- if (PtrListTail)
- PtrListTail->second.setTail(&Entry);
- else
- PtrListHead = &Entry;
- PtrListTail = &Entry;
+ assert(*PtrListEnd == 0 && "End of list is not null?");
+ *PtrListEnd = &Entry;
+ PtrListEnd = Entry.second.setPrevInList(PtrListEnd);
RefCount++; // Entry points to alias set...
}
@@ -253,6 +256,31 @@
}
}
+
+// remove method - This method is used to remove a pointer value from the
+// AliasSetTracker entirely. It should be used when an instruction is deleted
+// from the program to update the AST. If you don't use this, you would have
+// dangling pointers to deleted instructions.
+//
+void AliasSetTracker::remove(Value *PtrVal) {
+ // First, look up the PointerRec for this pointer...
+ hash_map<Value*, AliasSet::PointerRec>::iterator I = PointerMap.find(PtrVal);
+ if (I == PointerMap.end()) return; // Noop
+
+ // If we found one, remove the pointer from the alias set it is in.
+ AliasSet::HashNodePair &PtrValEnt = *I;
+ AliasSet *AS = PtrValEnt.second.getAliasSet(*this);
+
+ // Unlink from the list of values...
+ PtrValEnt.second.removeFromList();
+ // Stop using the alias set
+ if (--AS->RefCount == 0)
+ AS->removeFromTracker(*this);
+
+ PointerMap.erase(I);
+}
+
+
//===----------------------------------------------------------------------===//
// AliasSet/AliasSetTracker Printing Support
//===----------------------------------------------------------------------===//