Don't implement AliasSetTracker::remove in terms of deleteValue. deleteValue

causes the pointer to be removed from the underlying alias analysis
implementation as well.  This impl of remove is also significantly faster than
the old one.  This fixes:
Regression/Transforms/DeadStoreElimination/2006-06-27-AST-Remove.ll

llvm-svn: 28950

1 files changed, 22 insertions, 10 deletions

diff --git a/llvm/lib/Analysis/AliasSetTracker.cpp b/llvm/lib/Analysis/AliasSetTracker.cpp
index 83ba69a69d0..f805a43b4e7 100644
--- a/llvm/lib/Analysis/AliasSetTracker.cpp
+++ b/llvm/lib/Analysis/AliasSetTracker.cpp
@@ -359,16 +359,28 @@ void AliasSetTracker::add(const AliasSetTracker &AST) {
 /// remove - Remove the specified (potentially non-empty) alias set from the
 /// tracker.
 void AliasSetTracker::remove(AliasSet &AS) {
-  bool SetDead;
-  do {
-    AliasSet::iterator I = AS.begin();
-    Value *Ptr = I.getPointer(); ++I;
-
-    // deleteValue will delete the set automatically when the last pointer
-    // reference is destroyed.  "Predict" when this will happen.
-    SetDead = I == AS.end();
-    deleteValue(Ptr);  // Delete all of the pointers from the set
-  } while (!SetDead);
+  // Drop all call sites.
+  AS.CallSites.clear();
+  
+  // Clear the alias set.
+  unsigned NumRefs = 0;
+  while (!AS.empty()) {
+    AliasSet::HashNodePair *P = AS.PtrList;
+    
+    // Unlink from the list of values.
+    P->second.removeFromList();
+    
+    // Remember how many references need to be dropped.
+    ++NumRefs;
+
+    // Finally, remove the entry.
+    PointerMap.erase(P->first);
+  }
+  
+  // Stop using the alias set, removing it.
+  assert(AS.RefCount == NumRefs);
+  AS.RefCount = 0;
+  AS.removeFromTracker(*this);
 }
 
 bool AliasSetTracker::remove(Value *Ptr, unsigned Size) {