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authorChris Lattner <sabre@nondot.org>2003-12-18 08:11:56 +0000
committerChris Lattner <sabre@nondot.org>2003-12-18 08:11:56 +0000
commit2cffeec014537a5f4d2313a5c21c3aa6fcf33288 (patch)
tree7ea833c04e386c31b822e7ae698ac94a635f5ada /include
parent45ab10cb6ebe1e4b7efc5ee6aecc3ebe24829d70 (diff)
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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
Diffstat (limited to 'include')
-rw-r--r--include/llvm/Analysis/AliasSetTracker.h42
1 files changed, 33 insertions, 9 deletions
diff --git a/include/llvm/Analysis/AliasSetTracker.h b/include/llvm/Analysis/AliasSetTracker.h
index 2195253..77b1720 100644
--- a/include/llvm/Analysis/AliasSetTracker.h
+++ b/include/llvm/Analysis/AliasSetTracker.h
@@ -37,15 +37,20 @@ class AliasSet {
typedef std::pair<Value* const, PointerRec> HashNodePair;
class PointerRec {
- HashNodePair *NextInList;
+ HashNodePair **PrevInList, *NextInList;
AliasSet *AS;
unsigned Size;
public:
- PointerRec() : NextInList(0), AS(0), Size(0) {}
+ PointerRec() : PrevInList(0), NextInList(0), AS(0), Size(0) {}
HashNodePair *getNext() const { return NextInList; }
bool hasAliasSet() const { return AS != 0; }
+ HashNodePair** setPrevInList(HashNodePair **PIL) {
+ PrevInList = PIL;
+ return &NextInList;
+ }
+
void updateSize(unsigned NewSize) {
if (NewSize > Size) Size = NewSize;
}
@@ -68,13 +73,14 @@ class AliasSet {
assert(AS == 0 && "Already have an alias set!");
AS = as;
}
- void setTail(HashNodePair *T) {
- assert(NextInList == 0 && "Already have tail!");
- NextInList = T;
+
+ void removeFromList() {
+ if (NextInList) NextInList->second.PrevInList = PrevInList;
+ *PrevInList = NextInList;
}
};
- HashNodePair *PtrListHead, *PtrListTail; // Singly linked list of nodes
+ HashNodePair *PtrList, **PtrListEnd; // Doubly linked list of nodes
AliasSet *Forward; // Forwarding pointer
AliasSet *Next, *Prev; // Doubly linked list of AliasSets
@@ -135,7 +141,7 @@ public:
// Alias Set iteration - Allow access to all of the pointer which are part of
// this alias set...
class iterator;
- iterator begin() const { return iterator(PtrListHead); }
+ iterator begin() const { return iterator(PtrList); }
iterator end() const { return iterator(); }
void print(std::ostream &OS) const;
@@ -175,11 +181,22 @@ public:
private:
// Can only be created by AliasSetTracker
- AliasSet() : PtrListHead(0), PtrListTail(0), Forward(0), RefCount(0),
+ AliasSet() : PtrList(0), PtrListEnd(&PtrList), Forward(0), RefCount(0),
AccessTy(NoModRef), AliasTy(MustAlias), Volatile(false) {
}
+ AliasSet(const AliasSet &AS) {
+ // AliasSet's only get copy constructed in simple circumstances. In
+ // particular, they cannot have any pointers in their list. Despite this,
+ // we have to be sure to update the PtrListEnd to not point to the source
+ // AliasSet's list.
+ assert(AS.PtrList == 0 && "AliasSet has pointers in it!");
+ PtrList = 0; PtrListEnd = &PtrList;
+ Forward = AS.Forward; RefCount = AS.RefCount;
+ AccessTy = AS.AccessTy; AliasTy = AS.AliasTy; Volatile = AS.Volatile;
+ }
+
HashNodePair *getSomePointer() const {
- return PtrListHead ? PtrListHead : 0;
+ return PtrList;
}
/// getForwardedTarget - Return the real alias set this represents. If this
@@ -247,6 +264,13 @@ public:
void add(BasicBlock &BB); // Add all instructions in basic block
void add(const AliasSetTracker &AST); // Add alias relations from another AST
+ /// 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 remove(Value *PtrVal);
+
/// getAliasSets - Return the alias sets that are active.
const ilist<AliasSet> &getAliasSets() const { return AliasSets; }