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Teach ValueHandleBase to treat DenseMap's special Empty and Tombstone 

values the same way it treats null pointers. This is needed to allow
CallbackVH to be used as a key in a DenseMap.

llvm-svn: 77695
This commit is contained in:
Dan Gohman 2009-07-31 18:20:18 +00:00
parent 9d7de2a155
commit 0542060b8a
1 changed files with 14 additions and 7 deletions
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21
llvm/include/llvm/Support/ValueHandle.h
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@ -14,6 +14,7 @@
#ifndef LLVM_SUPPORT_VALUEHANDLE_H
#define LLVM_SUPPORT_VALUEHANDLE_H
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/Value.h"
@ -57,32 +58,32 @@ public:
: PrevPair(0, Kind), Next(0), VP(0) {}
ValueHandleBase(HandleBaseKind Kind, Value *V)
: PrevPair(0, Kind), Next(0), VP(V) {
if (V)
if (isValid(VP))
AddToUseList();
}
ValueHandleBase(HandleBaseKind Kind, const ValueHandleBase &RHS)
: PrevPair(0, Kind), Next(0), VP(RHS.VP) {
if (VP)
if (isValid(VP))
AddToExistingUseList(RHS.getPrevPtr());
}
~ValueHandleBase() {
if (VP)
if (isValid(VP))
RemoveFromUseList();
}
Value *operator=(Value *RHS) {
if (VP == RHS) return RHS;
if (VP) RemoveFromUseList();
if (isValid(VP)) RemoveFromUseList();
VP = RHS;
if (VP) AddToUseList();
if (isValid(VP)) AddToUseList();
return RHS;
}
Value *operator=(const ValueHandleBase &RHS) {
if (VP == RHS.VP) return RHS.VP;
if (VP) RemoveFromUseList();
if (isValid(VP)) RemoveFromUseList();
VP = RHS.VP;
if (VP) AddToExistingUseList(RHS.getPrevPtr());
if (isValid(VP)) AddToExistingUseList(RHS.getPrevPtr());
return VP;
}
@ -92,6 +93,12 @@ public:
protected:
Value *getValPtr() const { return VP; }
private:
static bool isValid(Value *V) {
return V &&
V != DenseMapInfo<Value *>::getEmptyKey() &&
V != DenseMapInfo<Value *>::getTombstoneKey();
}
// Callbacks made from Value.
static void ValueIsDeleted(Value *V);
static void ValueIsRAUWd(Value *Old, Value *New);