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BitstreamWriter: Isolate access to the underlying buffer.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151749 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Daniel Dunbar 2012-02-29 20:31:05 +00:00
parent 02a248afe3
commit a8d16bbdfb
1 changed files with 32 additions and 20 deletions
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52
include/llvm/Bitcode/BitstreamWriter.h
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@ -68,6 +68,27 @@ class BitstreamWriter {
Out[ByteNo ] = (unsigned char)(NewWord >> 24);
}
void WriteByte(unsigned char Value) {
Out.push_back(Value);
}
void WriteWord(unsigned Value) {
Out.push_back((unsigned char)(Value >> 0));
Out.push_back((unsigned char)(Value >> 8));
Out.push_back((unsigned char)(Value >> 16));
Out.push_back((unsigned char)(Value >> 24));
}
unsigned GetBufferOffset() const {
return Out.size();
}
unsigned GetWordIndex() const {
unsigned Offset = GetBufferOffset();
assert((Offset & 3) == 0 && "Not 32-bit aligned");
return Offset / 4;
}
public:
explicit BitstreamWriter(std::vector<unsigned char> &O)
: Out(O), CurBit(0), CurValue(0), CurCodeSize(2) {}
@ -88,7 +109,7 @@ public:
}
/// \brief Retrieve the current position in the stream, in bits.
uint64_t GetCurrentBitNo() const { return Out.size() * 8 + CurBit; }
uint64_t GetCurrentBitNo() const { return GetBufferOffset() * 8 + CurBit; }
//===--------------------------------------------------------------------===//
// Basic Primitives for emitting bits to the stream.
@ -104,11 +125,7 @@ public:
}
// Add the current word.
unsigned V = CurValue;
Out.push_back((unsigned char)(V >> 0));
Out.push_back((unsigned char)(V >> 8));
Out.push_back((unsigned char)(V >> 16));
Out.push_back((unsigned char)(V >> 24));
WriteWord(CurValue);
if (CurBit)
CurValue = Val >> (32-CurBit);
@ -128,11 +145,7 @@ public:
void FlushToWord() {
if (CurBit) {
unsigned V = CurValue;
Out.push_back((unsigned char)(V >> 0));
Out.push_back((unsigned char)(V >> 8));
Out.push_back((unsigned char)(V >> 16));
Out.push_back((unsigned char)(V >> 24));
WriteWord(CurValue);
CurBit = 0;
CurValue = 0;
}
@ -197,7 +210,7 @@ public:
EmitVBR(CodeLen, bitc::CodeLenWidth);
FlushToWord();
unsigned BlockSizeWordLoc = static_cast<unsigned>(Out.size());
unsigned BlockSizeWordIndex = GetWordIndex();
unsigned OldCodeSize = CurCodeSize;
// Emit a placeholder, which will be replaced when the block is popped.
@ -207,7 +220,7 @@ public:
// Push the outer block's abbrev set onto the stack, start out with an
// empty abbrev set.
BlockScope.push_back(Block(OldCodeSize, BlockSizeWordLoc/4));
BlockScope.push_back(Block(OldCodeSize, BlockSizeWordIndex));
BlockScope.back().PrevAbbrevs.swap(CurAbbrevs);
// If there is a blockinfo for this BlockID, add all the predefined abbrevs
@ -237,7 +250,7 @@ public:
FlushToWord();
// Compute the size of the block, in words, not counting the size field.
unsigned SizeInWords= static_cast<unsigned>(Out.size())/4-B.StartSizeWord-1;
unsigned SizeInWords = GetWordIndex() - B.StartSizeWord - 1;
unsigned ByteNo = B.StartSizeWord*4;
// Update the block size field in the header of this sub-block.
@ -353,25 +366,24 @@ private:
// Flush to a 32-bit alignment boundary.
FlushToWord();
assert((Out.size() & 3) == 0 && "Not 32-bit aligned");
// Emit each field as a literal byte.
if (BlobData) {
for (unsigned i = 0; i != BlobLen; ++i)
Out.push_back((unsigned char)BlobData[i]);
WriteByte((unsigned char)BlobData[i]);
// Know that blob data is consumed for assertion below.
BlobData = 0;
} else {
for (unsigned e = Vals.size(); RecordIdx != e; ++RecordIdx) {
assert(Vals[RecordIdx] < 256 && "Value too large to emit as blob");
Out.push_back((unsigned char)Vals[RecordIdx]);
WriteByte((unsigned char)Vals[RecordIdx]);
}
}
// Align end to 32-bits.
while (Out.size() & 3)
Out.push_back(0);
while (GetBufferOffset() & 3)
WriteByte(0);
} else { // Single scalar field.
assert(RecordIdx < Vals.size() && "Invalid abbrev/record");
EmitAbbreviatedField(Op, Vals[RecordIdx]);