Added "random access" to the Deserializer to allow a client to jump to any

serialized block in the bitstream, including a block in an entirely different
nesting than the current block. This is useful for deserializing objects from
a bitstream in an order different from the order that they were serialized.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43973 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ted Kremenek 2007-11-10 02:02:34 +00:00
parent 13faf5c13c
commit 1a8a08a690
2 changed files with 153 additions and 10 deletions

View File

@ -80,7 +80,36 @@ class Deserializer {
//===----------------------------------------------------------===//
public:
typedef uint64_t Location;
struct Location {
uint64_t BitNo;
unsigned BlockID;
unsigned NumWords;
Location(uint64_t bit, unsigned bid, unsigned words)
: BitNo(bit), BlockID(bid), NumWords(words) {}
Location() : BitNo(0), BlockID(0), NumWords(0) {}
Location& operator=(Location& RHS) {
BitNo = RHS.BitNo;
BlockID = RHS.BlockID;
NumWords = RHS.NumWords;
return *this;
}
bool operator==(const Location& RHS) const { return BitNo == RHS.BitNo; }
bool operator!=(const Location& RHS) const { return BitNo != RHS.BitNo; }
bool contains(const Location& RHS) const {
if (RHS.BitNo < BitNo)
return false;
if ((RHS.BitNo - BitNo) >> 5 < NumWords)
return true;
return false;
}
};
//===----------------------------------------------------------===//
// Internal data members.
@ -93,9 +122,10 @@ private:
BumpPtrAllocator Allocator;
BPNode* FreeList;
MapTy BPatchMap;
llvm::SmallVector<std::pair<Location,unsigned>,5> BlockStack;
llvm::SmallVector<Location,8> BlockStack;
unsigned AbbrevNo;
unsigned RecordCode;
Location StreamStart;
//===----------------------------------------------------------===//
// Public Interface.
@ -238,13 +268,18 @@ public:
unsigned getAbbrevNo();
bool FinishedBlock(Location BlockLoc);
bool JumpTo(const Location& BlockLoc);
void Rewind() { JumpTo(StreamStart); }
bool AtEnd();
bool inRecord();
void SkipBlock();
bool SkipToBlock(unsigned BlockID);
unsigned getRecordCode();
BitstreamReader& getStream() { return Stream; }
private:
bool AdvanceStream();
void ReadRecord();

View File

@ -21,6 +21,9 @@ using namespace llvm;
Deserializer::Deserializer(BitstreamReader& stream)
: Stream(stream), RecIdx(0), FreeList(NULL), AbbrevNo(0), RecordCode(0) {
AdvanceStream();
if (!AtEnd()) StreamStart = BlockStack.back();
}
Deserializer::~Deserializer() {
@ -60,12 +63,24 @@ bool Deserializer::AdvanceStream() {
while (!Stream.AtEndOfStream()) {
uint64_t Pos = Stream.GetCurrentBitNo();
AbbrevNo = Stream.ReadCode();
switch (AbbrevNo) {
case bitc::ENTER_SUBBLOCK: {
unsigned id = Stream.ReadSubBlockID();
BlockStack.push_back(std::make_pair(Stream.GetCurrentBitNo(),id));
// Determine the extent of the block. This is useful for jumping around
// the stream. This is hack: we read the header of the block, save
// the length, and then revert the bitstream to a location just before
// the block is entered.
uint64_t BPos = Stream.GetCurrentBitNo();
Stream.ReadVBR(bitc::CodeLenWidth); // Skip the code size.
Stream.SkipToWord();
unsigned NumWords = Stream.Read(bitc::BlockSizeWidth);
Stream.JumpToBit(BPos);
BlockStack.push_back(Location(Pos,id,NumWords));
break;
}
@ -91,10 +106,10 @@ bool Deserializer::AdvanceStream() {
}
void Deserializer::ReadRecord() {
while (AdvanceStream() && AbbrevNo == bitc::ENTER_SUBBLOCK) {
assert (!BlockStack.empty());
Stream.EnterSubBlock(BlockStack.back().second);
Stream.EnterSubBlock(BlockStack.back().BlockID);
AbbrevNo = 0;
}
@ -109,23 +124,116 @@ void Deserializer::ReadRecord() {
void Deserializer::SkipBlock() {
assert (!inRecord());
assert (AbbrevNo == bitc::ENTER_SUBBLOCK);
if (AtEnd())
return;
AdvanceStream();
assert (AbbrevNo == bitc::ENTER_SUBBLOCK);
BlockStack.pop_back();
Stream.SkipBlock();
AbbrevNo = 0;
AdvanceStream();
}
bool Deserializer::SkipToBlock(unsigned BlockID) {
assert (!inRecord());
AdvanceStream();
assert (AbbrevNo == bitc::ENTER_SUBBLOCK);
unsigned BlockLevel = BlockStack.size();
while (!AtEnd() &&
BlockLevel == BlockStack.size() &&
getCurrentBlockID() != BlockID)
SkipBlock();
return !(AtEnd() || BlockLevel != BlockStack.size());
}
Deserializer::Location Deserializer::getCurrentBlockLocation() {
if (!inRecord())
AdvanceStream();
return BlockStack.back().first;
return BlockStack.back();
}
bool Deserializer::JumpTo(const Location& Loc) {
assert (!inRecord());
// AdvanceStream();
// assert (AbbrevNo == bitc::ENTER_SUBBLOCK);
assert (!BlockStack.empty());
uint64_t LastBPos = StreamStart.BitNo;
while (!BlockStack.empty()) {
LastBPos = BlockStack.back().BitNo;
// Determine of the current block contains the location of the block
// we are looking for.
if (BlockStack.back().contains(Loc)) {
// We found the enclosing block. We must first POP it off to
// destroy any accumulated context within the block scope. We then
// jump to the position of the block and enter it.
Stream.JumpToBit(LastBPos);
BlockStack.pop_back();
Stream.PopBlockScope();
AbbrevNo = 0;
AdvanceStream();
assert (AbbrevNo == bitc::ENTER_SUBBLOCK);
Stream.EnterSubBlock(BlockStack.back().BlockID);
break;
}
// This block does not contain the block we are looking for. Pop it.
BlockStack.pop_back();
Stream.PopBlockScope();
}
// Check if we have popped our way to the outermost scope. If so,
// we need to adjust our position.
if (BlockStack.empty()) {
Stream.JumpToBit(Loc.BitNo < LastBPos ? StreamStart.BitNo : LastBPos);
AbbrevNo = 0;
AdvanceStream();
}
assert (AbbrevNo == bitc::ENTER_SUBBLOCK);
assert (!BlockStack.empty());
while (!AtEnd() && BlockStack.back() != Loc) {
if (BlockStack.back().contains(Loc)) {
Stream.EnterSubBlock(BlockStack.back().BlockID);
AbbrevNo = 0;
AdvanceStream();
continue;
}
else
SkipBlock();
}
if (AtEnd())
return false;
assert (BlockStack.back() == Loc);
return true;
}
unsigned Deserializer::getCurrentBlockID() {
if (!inRecord())
AdvanceStream();
return BlockStack.back().second;
return BlockStack.back().BlockID;
}
unsigned Deserializer::getRecordCode() {
@ -142,9 +250,9 @@ bool Deserializer::FinishedBlock(Location BlockLoc) {
if (!inRecord())
AdvanceStream();
for (llvm::SmallVector<std::pair<Location,unsigned>,5>::reverse_iterator
for (llvm::SmallVector<Location,8>::reverse_iterator
I=BlockStack.rbegin(), E=BlockStack.rend(); I!=E; ++I)
if (I->first == BlockLoc)
if (*I == BlockLoc)
return false;
return true;