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-rw-r--r--llvm/include/llvm/Support/ValueHandle.h217
-rw-r--r--llvm/include/llvm/Value.h8
-rw-r--r--llvm/lib/VMCore/Value.cpp167
3 files changed, 389 insertions, 3 deletions
diff --git a/llvm/include/llvm/Support/ValueHandle.h b/llvm/include/llvm/Support/ValueHandle.h
new file mode 100644
index 00000000000..0494b27019c
--- /dev/null
+++ b/llvm/include/llvm/Support/ValueHandle.h
@@ -0,0 +1,217 @@
+//===- llvm/Support/ValueHandle.h - Value Smart Pointer classes -*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the ValueHandle class and its sub-classes.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_VALUEHANDLE_H
+#define LLVM_SUPPORT_VALUEHANDLE_H
+
+#include "llvm/ADT/PointerIntPair.h"
+#include "llvm/Value.h"
+
+namespace llvm {
+
+/// ValueHandleBase - This is the common base class of value handles.
+/// ValueHandle's are smart pointers to Value's that have special behavior when
+/// the value is deleted or ReplaceAllUsesWith'd. See the specific handles
+/// below for details.
+///
+class ValueHandleBase {
+ friend class Value;
+protected:
+ /// HandleBaseKind - This indicates what base class the handle actually is.
+ /// This is to avoid having a vtable for the light-weight handle pointers. The
+ /// fully generally Callback version does have a vtable.
+ enum HandleBaseKind {
+ Assert,
+ Weak,
+ Callback
+ };
+private:
+
+ PointerIntPair<ValueHandleBase**, 2, HandleBaseKind> PrevPair;
+ ValueHandleBase *Next;
+ Value *VP;
+public:
+ ValueHandleBase(HandleBaseKind Kind) : PrevPair(0, Kind), Next(0), VP(0) {}
+ ValueHandleBase(HandleBaseKind Kind, Value *V)
+ : PrevPair(0, Kind), Next(0), VP(V) {
+ if (V)
+ AddToUseList();
+ }
+ ValueHandleBase(HandleBaseKind Kind, const ValueHandleBase &RHS)
+ : PrevPair(0, Kind), Next(0), VP(RHS.VP) {
+ if (VP)
+ AddToExistingUseList(RHS.getPrevPtr());
+ }
+ ~ValueHandleBase() {
+ if (VP)
+ RemoveFromUseList();
+ }
+
+ Value *operator=(Value *RHS) {
+ if (VP == RHS) return RHS;
+ if (VP) RemoveFromUseList();
+ VP = RHS;
+ if (VP) AddToUseList();
+ return RHS;
+ }
+
+ Value *operator=(const ValueHandleBase &RHS) {
+ if (VP == RHS.VP) return RHS.VP;
+ if (VP) RemoveFromUseList();
+ VP = RHS.VP;
+ if (VP) AddToExistingUseList(RHS.getPrevPtr());
+ return VP;
+ }
+
+ Value *operator->() const { return getValPtr(); }
+ Value &operator*() const { return *getValPtr(); }
+
+ bool operator==(const Value *RHS) const { return VP == RHS; }
+ bool operator==(const ValueHandleBase &RHS) const { return VP == RHS.VP; }
+ bool operator!=(const Value *RHS) const { return VP != RHS; }
+ bool operator!=(const ValueHandleBase &RHS) const { return VP != RHS.VP; }
+ bool operator<(const Value *RHS) const { return VP < RHS; }
+ bool operator<(const ValueHandleBase &RHS) const { return VP < RHS.VP; }
+ bool operator>(const Value *RHS) const { return VP > RHS; }
+ bool operator>(const ValueHandleBase &RHS) const { return VP > RHS.VP; }
+ bool operator<=(const Value *RHS) const { return VP <= RHS; }
+ bool operator<=(const ValueHandleBase &RHS) const { return VP <= RHS.VP; }
+ bool operator>=(const Value *RHS) const { return VP >= RHS; }
+ bool operator>=(const ValueHandleBase &RHS) const { return VP >= RHS.VP; }
+
+protected:
+ Value *getValPtr() const { return VP; }
+private:
+ // Callbacks made from Value.
+ static void ValueIsDeleted(Value *V);
+ static void ValueIsRAUWd(Value *Old, Value *New);
+
+ // Internal implementation details.
+ ValueHandleBase **getPrevPtr() const { return PrevPair.getPointer(); }
+ HandleBaseKind getKind() const { return PrevPair.getInt(); }
+ void setPrevPtr(ValueHandleBase **Ptr) { PrevPair.setPointer(Ptr); }
+
+ /// AddToUseList - Add this ValueHandle to the use list for VP, where List is
+ /// known to point into the existing use list.
+ void AddToExistingUseList(ValueHandleBase **List);
+
+ /// AddToUseList - Add this ValueHandle to the use list for VP.
+ void AddToUseList();
+ /// RemoveFromUseList - Remove this ValueHandle from its current use list.
+ void RemoveFromUseList();
+};
+
+/// WeakVH - This is a value handle that tries hard to point to a Value, even
+/// across RAUW operations, but will null itself out if the value is destroyed.
+/// this is useful for advisory sorts of information, but should not be used as
+/// the key of a map (since the map would have to rearrange itself when the
+/// pointer changes).
+class WeakVH : public ValueHandleBase {
+public:
+ WeakVH() : ValueHandleBase(Weak) {}
+ WeakVH(Value *P) : ValueHandleBase(Weak, P) {}
+ WeakVH(const WeakVH &RHS)
+ : ValueHandleBase(Weak, RHS) {}
+
+};
+
+/// AssertingVH - This is a Value Handle that points to a value and asserts out
+/// if the value is destroyed while the handle is still live. This is very
+/// useful for catching dangling pointer bugs and other things which can be
+/// non-obvious. One particularly useful place to use this is as the Key of a
+/// map. Dangling pointer bugs often lead to really subtle bugs that only occur
+/// if another object happens to get allocated to the same address as the old
+/// one. Using an AssertingVH ensures that an assert is triggered as soon as
+/// the bad delete occurs.
+///
+/// Note that an AssertingVH handle does *not* follow values across RAUW
+/// operations. This means that RAUW's need to explicitly update the
+/// AssertingVH's as it moves. This is required because in non-assert mode this
+ /// class turns into a trivial wrapper around a pointer.
+template <typename ValueTy = Value>
+class AssertingVH
+#ifndef NDEBUG
+ : public ValueHandleBase
+#endif
+ {
+
+#ifndef NDEBUG
+ ValueTy *getValPtr() const {
+ return static_cast<ValueTy*>(ValueHandleBase::getValPtr());
+ }
+ void setValPtr(ValueTy *P) {
+ ValueHandleBase::operator=(P);
+ }
+#else
+ ValueTy *ThePtr;
+ ValueTy *getValPtr() const { return ThePtr; }
+ void setValPtr(ValueTy *P) { ThePtr = P; }
+#endif
+
+public:
+#ifndef NDEBUG
+ AssertingVH() : ValueHandleBase(Assert) {}
+ AssertingVH(ValueTy *P) : ValueHandleBase(Assert, P) {}
+ AssertingVH(const AssertingVH &RHS) : ValueHandleBase(Assert, RHS) {}
+#else
+ AssertingVH() : ThePtr(0) {}
+ AssertingVH(ValueTy *P) : ThePtr(P) {}
+#endif
+
+ operator ValueTy*() const {
+ return getValPtr();
+ }
+
+ ValueTy *operator=(ValueTy *RHS) {
+ setValPtr(RHS);
+ return getValPtr();
+ }
+ ValueTy *operator=(AssertingVH<ValueTy> &RHS) {
+ setValPtr(RHS.getValPtr());
+ return getValPtr();
+ }
+
+ ValueTy *operator->() const { return getValPtr(); }
+ ValueTy &operator*() const { return getValPtr(); }
+
+ // Duplicate these from the base class so that they work when assertions are
+ // off.
+ bool operator==(const Value *RHS) const { return getValPtr() == RHS; }
+ bool operator!=(const Value *RHS) const { return getValPtr() != RHS; }
+ bool operator<(const Value *RHS) const { return getValPtr() < RHS; }
+ bool operator>(const Value *RHS) const { return getValPtr() > RHS; }
+ bool operator<=(const Value *RHS) const { return getValPtr() <= RHS; }
+ bool operator>=(const Value *RHS) const { return getValPtr() >= RHS; }
+ bool operator==(const AssertingVH &RHS) const {
+ return getValPtr() == RHS.getValPtr();
+ }
+ bool operator!=(const AssertingVH &RHS) const {
+ return getValPtr() != RHS.getValPtr();
+ }
+ bool operator<(const AssertingVH &RHS) const {
+ return getValPtr() < RHS.getValPtr();
+ }
+ bool operator>(const AssertingVH &RHS) const {
+ return getValPtr() > RHS.getValPtr();
+ }
+ bool operator<=(const AssertingVH &RHS) const {
+ return getValPtr() <= RHS.getValPtr();
+ }
+ bool operator>=(const AssertingVH &RHS) const {
+ return getValPtr() >= RHS.getValPtr();
+ }
+};
+
+} // End llvm namespace
+
+#endif
diff --git a/llvm/include/llvm/Value.h b/llvm/include/llvm/Value.h
index 3600a5cef31..531d560a9c4 100644
--- a/llvm/include/llvm/Value.h
+++ b/llvm/include/llvm/Value.h
@@ -37,6 +37,7 @@ template<typename ValueTy> class StringMapEntry;
typedef StringMapEntry<Value*> ValueName;
class raw_ostream;
class AssemblyAnnotationWriter;
+class ValueHandleBase;
//===----------------------------------------------------------------------===//
// Value Class
@@ -50,10 +51,14 @@ class AssemblyAnnotationWriter;
/// automatically updates the module's symbol table.
///
/// Every value has a "use list" that keeps track of which other Values are
-/// using this Value.
+/// using this Value. A Value can also have an arbitrary number of ValueHandle
+/// objects that watch it and listen to RAUW and Destroy events see
+/// llvm/Support/ValueHandle.h for details.
+///
/// @brief LLVM Value Representation
class Value {
const unsigned char SubclassID; // Subclass identifier (for isa/dyn_cast)
+ unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this?
protected:
/// SubclassData - This member is defined by this class, but is not used for
/// anything. Subclasses can use it to hold whatever state they find useful.
@@ -65,6 +70,7 @@ private:
friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
friend class SymbolTable; // Allow SymbolTable to directly poke Name.
+ friend class ValueHandleBase;
ValueName *Name;
void operator=(const Value &); // Do not implement
diff --git a/llvm/lib/VMCore/Value.cpp b/llvm/lib/VMCore/Value.cpp
index 0aa2db44399..499b936e29c 100644
--- a/llvm/lib/VMCore/Value.cpp
+++ b/llvm/lib/VMCore/Value.cpp
@@ -7,7 +7,7 @@
//
//===----------------------------------------------------------------------===//
//
-// This file implements the Value and User classes.
+// This file implements the Value, ValueHandle, and User classes.
//
//===----------------------------------------------------------------------===//
@@ -20,6 +20,9 @@
#include "llvm/ValueSymbolTable.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/LeakDetector.h"
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/ValueHandle.h"
+#include "llvm/ADT/DenseMap.h"
#include <algorithm>
using namespace llvm;
@@ -33,7 +36,7 @@ static inline const Type *checkType(const Type *Ty) {
}
Value::Value(const Type *ty, unsigned scid)
- : SubclassID(scid), SubclassData(0), VTy(checkType(ty)),
+ : SubclassID(scid), HasValueHandle(0), SubclassData(0), VTy(checkType(ty)),
UseList(0), Name(0) {
if (isa<CallInst>(this) || isa<InvokeInst>(this))
assert((VTy->isFirstClassType() || VTy == Type::VoidTy ||
@@ -46,6 +49,10 @@ Value::Value(const Type *ty, unsigned scid)
}
Value::~Value() {
+ // Notify all ValueHandles (if present) that this value is going away.
+ if (HasValueHandle)
+ ValueHandleBase::ValueIsDeleted(this);
+
#ifndef NDEBUG // Only in -g mode...
// Check to make sure that there are no uses of this value that are still
// around when the value is destroyed. If there are, then we have a dangling
@@ -297,6 +304,10 @@ void Value::takeName(Value *V) {
// this problem.
//
void Value::uncheckedReplaceAllUsesWith(Value *New) {
+ // Notify all ValueHandles (if present) that this value is going away.
+ if (HasValueHandle)
+ ValueHandleBase::ValueIsRAUWd(this, New);
+
while (!use_empty()) {
Use &U = *UseList;
// Must handle Constants specially, we cannot call replaceUsesOfWith on a
@@ -383,6 +394,158 @@ Value *Value::DoPHITranslation(const BasicBlock *CurBB,
return this;
}
+//===----------------------------------------------------------------------===//
+// ValueHandleBase Class
+//===----------------------------------------------------------------------===//
+
+/// ValueHandles - This map keeps track of all of the value handles that are
+/// watching a Value*. The Value::HasValueHandle bit is used to know whether or
+/// not a value has an entry in this map.
+typedef DenseMap<Value*, ValueHandleBase*> ValueHandlesTy;
+static ManagedStatic<ValueHandlesTy> ValueHandles;
+
+/// AddToUseList - Add this ValueHandle to the use list for VP, where List is
+/// known to point into the existing use list.
+void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
+ assert(List && "Handle list is null?");
+
+ // Splice ourselves into the list.
+ Next = *List;
+ *List = this;
+ setPrevPtr(List);
+ if (Next) {
+ Next->setPrevPtr(&Next);
+ assert(VP == Next->VP && "Added to wrong list?");
+ }
+}
+
+/// AddToUseList - Add this ValueHandle to the use list for VP.
+void ValueHandleBase::AddToUseList() {
+ assert(VP && "Null pointer doesn't have a use list!");
+ if (VP->HasValueHandle) {
+ // If this value already has a ValueHandle, then it must be in the
+ // ValueHandles map already.
+ ValueHandleBase *&Entry = (*ValueHandles)[VP];
+ assert(Entry != 0 && "Value doesn't have any handles?");
+ return AddToExistingUseList(&Entry);
+ }
+
+ // Ok, it doesn't have any handles yet, so we must insert it into the
+ // DenseMap. However, doing this insertion could cause the DenseMap to
+ // reallocate itself, which would invalidate all of the PrevP pointers that
+ // point into the old table. Handle this by checking for reallocation and
+ // updating the stale pointers only if needed.
+ ValueHandlesTy &Handles = *ValueHandles;
+ const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
+
+ ValueHandleBase *&Entry = Handles[VP];
+ assert(Entry == 0 && "Value really did already have handles?");
+ AddToExistingUseList(&Entry);
+ VP->HasValueHandle = 1;
+
+ // If reallocation didn't happen or if this was the first insertion, don't
+ // walk the table.
+ if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
+ Handles.size() == 1)
+ return;
+
+ // Okay, reallocation did happen. Fix the Prev Pointers.
+ for (ValueHandlesTy::iterator I = Handles.begin(), E = Handles.end();
+ I != E; ++I) {
+ assert(I->second && I->first == I->second->VP && "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!");
+
+ // Unlink this from its use list.
+ ValueHandleBase **PrevPtr = getPrevPtr();
+ assert(*PrevPtr == this && "List invariant broken");
+
+ *PrevPtr = Next;
+ if (Next) {
+ assert(Next->getPrevPtr() == &Next && "List invariant broken");
+ Next->setPrevPtr(PrevPtr);
+ return;
+ }
+
+ // 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.
+ ValueHandlesTy &Handles = *ValueHandles;
+ if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
+ Handles.erase(VP);
+ VP->HasValueHandle = false;
+ }
+}
+
+
+void ValueHandleBase::ValueIsDeleted(Value *V) {
+ assert(V->HasValueHandle && "Should only be called if ValueHandles present");
+
+ // Get the linked list base, which is guaranteed to exist since the
+ // HasValueHandle flag is set.
+ ValueHandleBase *Entry = (*ValueHandles)[V];
+ assert(Entry && "Value bit set but no entries exist");
+
+ while (Entry) {
+ // Advance pointer to avoid invalidation.
+ ValueHandleBase *ThisNode = Entry;
+ Entry = Entry->Next;
+
+ switch (ThisNode->getKind()) {
+ case Assert:
+#ifndef NDEBUG // Only in -g mode...
+ cerr << "While deleting: " << *V->getType() << " %" << V->getNameStr()
+ << "\n";
+#endif
+ cerr << "An asserting value handle still pointed to this value!\n";
+ abort();
+ case Weak:
+ // Weak just goes to null, which will unlink it from the list.
+ ThisNode->operator=(0);
+ break;
+ case Callback:
+ assert(0 && "Callback not implemented yet!");
+ }
+ }
+
+ // All callbacks and weak references should be dropped by now.
+ assert(!V->HasValueHandle && "All references to V were not removed?");
+}
+
+
+void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
+ assert(Old->HasValueHandle &&"Should only be called if ValueHandles present");
+ assert(Old != New && "Changing value into itself!");
+
+ // Get the linked list base, which is guaranteed to exist since the
+ // HasValueHandle flag is set.
+ ValueHandleBase *Entry = (*ValueHandles)[Old];
+ assert(Entry && "Value bit set but no entries exist");
+
+ while (Entry) {
+ // Advance pointer to avoid invalidation.
+ ValueHandleBase *ThisNode = Entry;
+ Entry = Entry->Next;
+
+ switch (ThisNode->getKind()) {
+ case Assert:
+ // Asserting handle does not follow RAUW implicitly.
+ break;
+ case Weak:
+ // Weak goes to the new value, which will unlink it from Old's list.
+ ThisNode->operator=(New);
+ break;
+ case Callback:
+ assert(0 && "Callback not implemented yet!");
+ }
+ }
+}
+
//===----------------------------------------------------------------------===//
// User Class
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