Allow subclasses of the ValueHandleBase to store information as part of the

value pointer by making the value pointer into a pointer-int pair with 2 bits
available for flags.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154279 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 40 insertions, 29 deletions

diff --git a/include/llvm/Support/ValueHandle.h b/include/llvm/Support/ValueHandle.h
index c0cdc35e99..b7210b2063 100644
--- a/include/llvm/Support/ValueHandle.h
+++ b/include/llvm/Support/ValueHandle.h
@@ -49,52 +49,61 @@ protected:
     Tracking,
     Weak
   };
-private:
 
+private:
   PointerIntPair<ValueHandleBase**, 2, HandleBaseKind> PrevPair;
   ValueHandleBase *Next;
-  Value *VP;
+
+  // A subclass may want to store some information along with the value
+  // pointer. Allow them to do this by making the value pointer a pointer-int
+  // pair. The 'setValPtrInt' and 'getValPtrInt' methods below give them this
+  // access.
+  PointerIntPair<Value*, 2> VP;
   
   explicit ValueHandleBase(const ValueHandleBase&); // DO NOT IMPLEMENT.
 public:
   explicit ValueHandleBase(HandleBaseKind Kind)
-    : PrevPair(0, Kind), Next(0), VP(0) {}
+    : PrevPair(0, Kind), Next(0), VP(0, 0) {}
   ValueHandleBase(HandleBaseKind Kind, Value *V)
-    : PrevPair(0, Kind), Next(0), VP(V) {
-    if (isValid(VP))
+    : PrevPair(0, Kind), Next(0), VP(V, 0) {
+    if (isValid(VP.getPointer()))
       AddToUseList();
   }
   ValueHandleBase(HandleBaseKind Kind, const ValueHandleBase &RHS)
     : PrevPair(0, Kind), Next(0), VP(RHS.VP) {
-    if (isValid(VP))
+    if (isValid(VP.getPointer()))
       AddToExistingUseList(RHS.getPrevPtr());
   }
   ~ValueHandleBase() {
-    if (isValid(VP))
+    if (isValid(VP.getPointer()))
       RemoveFromUseList();
   }
 
   Value *operator=(Value *RHS) {
-    if (VP == RHS) return RHS;
-    if (isValid(VP)) RemoveFromUseList();
-    VP = RHS;
-    if (isValid(VP)) AddToUseList();
+    if (VP.getPointer() == RHS) return RHS;
+    if (isValid(VP.getPointer())) RemoveFromUseList();
+    VP.setPointer(RHS);
+    if (isValid(VP.getPointer())) AddToUseList();
     return RHS;
   }
 
   Value *operator=(const ValueHandleBase &RHS) {
-    if (VP == RHS.VP) return RHS.VP;
-    if (isValid(VP)) RemoveFromUseList();
-    VP = RHS.VP;
-    if (isValid(VP)) AddToExistingUseList(RHS.getPrevPtr());
-    return VP;
+    if (VP.getPointer() == RHS.VP.getPointer()) return RHS.VP.getPointer();
+    if (isValid(VP.getPointer())) RemoveFromUseList();
+    VP.setPointer(RHS.VP.getPointer());
+    if (isValid(VP.getPointer())) AddToExistingUseList(RHS.getPrevPtr());
+    return VP.getPointer();
   }
 
   Value *operator->() const { return getValPtr(); }
   Value &operator*() const { return *getValPtr(); }
 
 protected:
-  Value *getValPtr() const { return VP; }
+  Value *getValPtr() const { return VP.getPointer(); }
+
+  void setValPtrInt(unsigned K) { VP.setInt(K); }
+  unsigned getValPtrInt() const { return VP.getInt(); }
+
   static bool isValid(Value *V) {
     return V &&
            V != DenseMapInfo<Value *>::getEmptyKey() &&
diff --git a/lib/VMCore/Value.cpp b/lib/VMCore/Value.cpp
index 41cc38c90a..788f4191f5 100644
--- a/lib/VMCore/Value.cpp
+++ b/lib/VMCore/Value.cpp
@@ -477,7 +477,7 @@ void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
   setPrevPtr(List);
   if (Next) {
     Next->setPrevPtr(&Next);
-    assert(VP == Next->VP && "Added to wrong list?");
+    assert(VP.getPointer() == Next->VP.getPointer() && "Added to wrong list?");
   }
 }
 
@@ -493,14 +493,14 @@ void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase *List) {
 
 /// AddToUseList - Add this ValueHandle to the use list for VP.
 void ValueHandleBase::AddToUseList() {
-  assert(VP && "Null pointer doesn't have a use list!");
+  assert(VP.getPointer() && "Null pointer doesn't have a use list!");
 
-  LLVMContextImpl *pImpl = VP->getContext().pImpl;
+  LLVMContextImpl *pImpl = VP.getPointer()->getContext().pImpl;
 
-  if (VP->HasValueHandle) {
+  if (VP.getPointer()->HasValueHandle) {
     // If this value already has a ValueHandle, then it must be in the
     // ValueHandles map already.
-    ValueHandleBase *&Entry = pImpl->ValueHandles[VP];
+    ValueHandleBase *&Entry = pImpl->ValueHandles[VP.getPointer()];
     assert(Entry != 0 && "Value doesn't have any handles?");
     AddToExistingUseList(&Entry);
     return;
@@ -514,10 +514,10 @@ void ValueHandleBase::AddToUseList() {
   DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
   const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
 
-  ValueHandleBase *&Entry = Handles[VP];
+  ValueHandleBase *&Entry = Handles[VP.getPointer()];
   assert(Entry == 0 && "Value really did already have handles?");
   AddToExistingUseList(&Entry);
-  VP->HasValueHandle = true;
+  VP.getPointer()->HasValueHandle = true;
 
   // If reallocation didn't happen or if this was the first insertion, don't
   // walk the table.
@@ -529,14 +529,16 @@ void ValueHandleBase::AddToUseList() {
   // Okay, reallocation did happen.  Fix the Prev Pointers.
   for (DenseMap<Value*, ValueHandleBase*>::iterator I = Handles.begin(),
        E = Handles.end(); I != E; ++I) {
-    assert(I->second && I->first == I->second->VP && "List invariant broken!");
+    assert(I->second && I->first == I->second->VP.getPointer() &&
+           "List invariant broken!");
     I->second->setPrevPtr(&I->second);
   }
 }
 
 /// RemoveFromUseList - Remove this ValueHandle from its current use list.
 void ValueHandleBase::RemoveFromUseList() {
-  assert(VP && VP->HasValueHandle && "Pointer doesn't have a use list!");
+  assert(VP.getPointer() && VP.getPointer()->HasValueHandle &&
+         "Pointer doesn't have a use list!");
 
   // Unlink this from its use list.
   ValueHandleBase **PrevPtr = getPrevPtr();
@@ -552,11 +554,11 @@ void ValueHandleBase::RemoveFromUseList() {
   // If the Next pointer was null, then it is possible that this was the last
   // ValueHandle watching VP.  If so, delete its entry from the ValueHandles
   // map.
-  LLVMContextImpl *pImpl = VP->getContext().pImpl;
+  LLVMContextImpl *pImpl = VP.getPointer()->getContext().pImpl;
   DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
   if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
-    Handles.erase(VP);
-    VP->HasValueHandle = false;
+    Handles.erase(VP.getPointer());
+    VP.getPointer()->HasValueHandle = false;
   }
 }