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Updated backpatching logic during object deserialization to perform

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eager backpatching instead of waithing until all objects have been
deserialized.  This allows us to reduce the memory footprint needed
for backpatching.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43422 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ted Kremenek
2007-10-28 21:17:59 +00:00
parent dc84650679
commit 5973ef40ca
2 changed files with 91 additions and 43 deletions
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62
lib/Bitcode/Reader/Deserialize.cpp
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@ -16,14 +16,14 @@
using namespace llvm;
Deserializer::Deserializer(BitstreamReader& stream)
: Stream(stream), RecIdx(0) {
: Stream(stream), RecIdx(0), FreeList(NULL) {
}
Deserializer::~Deserializer() {
assert (RecIdx >= Record.size() &&
"Still scanning bitcode record when deserialization completed.");
BackpatchPointers();
assert (FreeList == NULL && "Some pointers were not backpatched.");
}
@ -96,11 +96,11 @@ void Deserializer::ReadCStr(std::vector<char>& buff, bool isNullTerm) {
void Deserializer::RegisterPtr(unsigned PtrId,void* Ptr) {
BPatchEntry& E = BPatchMap[PtrId];
assert (E.Ptr == NULL && "Pointer already registered.");
E.Ptr = Ptr;
assert (E.hasFinalPtr() && "Pointer already registered.");
E.setFinalPtr(FreeList,Ptr);
}
void Deserializer::ReadPtr(void*& PtrRef) {
void Deserializer::ReadUIntPtr(uintptr_t& PtrRef) {
unsigned PtrId = ReadInt();
if (PtrId == 0) {
@ -110,32 +110,46 @@ void Deserializer::ReadPtr(void*& PtrRef) {
BPatchEntry& E = BPatchMap[PtrId];
if (E.Ptr == NULL) {
// Register backpatch.
void* P = Allocator.Allocate<BPatchNode>();
E.Head = new (P) BPatchNode(E.Head,PtrRef);
if (E.hasFinalPtr())
PtrRef = E.getRawPtr();
else {
// Register backpatch. Check the freelist for a BPNode.
BPNode* N;
if (FreeList) {
N = FreeList;
FreeList = FreeList->Next;
}
else // No available BPNode. Allocate one.
N = (BPNode*) Allocator.Allocate<BPNode>();
new (N) BPNode(E.getBPNode(),PtrRef);
E.setBPNode(N);
}
else
PtrRef = E.Ptr;
}
void Deserializer::BackpatchPointers() {
for (MapTy::iterator I=BPatchMap.begin(),E=BPatchMap.end(); I!=E; ++I) {
BPatchEntry& Entry = I->second;
assert (Entry.Ptr && "No pointer found for backpatch.");
for (BPatchNode* N = Entry.Head; N != NULL; N = N->Next)
// Bitwise-OR in the pointer to support "smart" pointers that use
// unused bits to store extra data.
N->PtrRef |= reinterpret_cast<uintptr_t>(Entry.Ptr);
Entry.Head = NULL;
void Deserializer::BPatchEntry::setFinalPtr(BPNode*& FreeList, void* P) {
assert (!hasFinalPtr());
// Perform backpatching.
BPNode* Last = NULL;
for (BPNode* N = getBPNode() ; N != NULL; N = N->Next) {
Last = N;
N->PtrRef |= reinterpret_cast<uintptr_t>(P);
}
Allocator.Reset();
if (Last) {
Last->Next = FreeList;
FreeList = getBPNode();
}
Ptr = reinterpret_cast<uintptr_t>(P);
}
#define INT_READ(TYPE)\
void SerializeTrait<TYPE>::Read(Deserializer& D, TYPE& X) {\
X = (TYPE) D.ReadInt(); }\