BitstreamEntry E; E.Kind = Record; E.ID = AbbrevID; return E;
}
};
-
/// BitstreamCursor - This represents a position within a bitcode file. There
/// may be multiple independent cursors reading within one bitstream, each
BitstreamReader *BitStream;
size_t NextChar;
- /// CurWord - This is the current data we have pulled from the stream but have
- /// not returned to the client.
- uint32_t CurWord;
+
+ /// CurWord/word_t - This is the current data we have pulled from the stream
+ /// but have not returned to the client. This is specifically and
+ /// intentionally defined to follow the word size of the host machine for
+ /// efficiency. We use word_t in places that are aware of this to make it
+ /// perfectly explicit what is going on.
+ typedef uint32_t word_t;
+ word_t CurWord;
/// BitsInCurWord - This is the number of bits in CurWord that are valid. This
- /// is always from [0...31] inclusive.
+ /// is always from [0...31/63] inclusive (depending on word size).
unsigned BitsInCurWord;
// CurCodeSize - This is the declared size of code values used for the current
static_cast<uint64_t>(pos - 1));
}
- unsigned char getByte(size_t pos) {
- uint8_t byte = -1;
- BitStream->getBitcodeBytes().readByte(pos, &byte);
- return byte;
- }
-
uint32_t getWord(size_t pos) {
uint8_t buf[4] = { 0xFF, 0xFF, 0xFF, 0xFF };
BitStream->getBitcodeBytes().readBytes(pos, sizeof(buf), buf, NULL);
}
bool AtEndOfStream() {
- return isEndPos(NextChar) && BitsInCurWord == 0;
+ return BitsInCurWord == 0 && isEndPos(NextChar);
}
/// getAbbrevIDWidth - Return the number of bits used to encode an abbrev #.
/// JumpToBit - Reset the stream to the specified bit number.
void JumpToBit(uint64_t BitNo) {
- uintptr_t ByteNo = uintptr_t(BitNo/8) & ~3;
- uintptr_t WordBitNo = uintptr_t(BitNo) & 31;
+ uintptr_t ByteNo = uintptr_t(BitNo/8) & ~(sizeof(word_t)-1);
+ unsigned WordBitNo = unsigned(BitNo & (sizeof(word_t)*8-1));
assert(canSkipToPos(ByteNo) && "Invalid location");
// Move the cursor to the right word.
CurWord = 0;
// Skip over any bits that are already consumed.
- if (WordBitNo)
- Read(static_cast<unsigned>(WordBitNo));
+ if (WordBitNo) {
+ if (sizeof(word_t) > 4)
+ Read64(WordBitNo);
+ else
+ Read(WordBitNo);
+ }
}
uint32_t Read(unsigned NumBits) {
- assert(NumBits <= 32 && "Cannot return more than 32 bits!");
+ assert(NumBits && NumBits <= 32 &&
+ "Cannot return zero or more than 32 bits!");
+
// If the field is fully contained by CurWord, return it quickly.
if (BitsInCurWord >= NumBits) {
- uint32_t R = CurWord & ((1U << NumBits)-1);
+ uint32_t R = uint32_t(CurWord) & (~0U >> (32-NumBits));
CurWord >>= NumBits;
BitsInCurWord -= NumBits;
return R;
return 0;
}
- unsigned R = CurWord;
+ uint32_t R = uint32_t(CurWord);
// Read the next word from the stream.
- CurWord = getWord(NextChar);
- NextChar += 4;
+ uint8_t buf[sizeof(word_t)] = {0};
+ BitStream->getBitcodeBytes().readBytes(NextChar, sizeof(buf), buf, NULL);
+
+ typedef support::detail::packed_endian_specific_integral
+ <word_t, support::little, support::unaligned> Endian_T;
+ CurWord = *reinterpret_cast<Endian_T*>(buf);
+
+ NextChar += sizeof(word_t);
// Extract NumBits-BitsInCurWord from what we just read.
unsigned BitsLeft = NumBits-BitsInCurWord;
- // Be careful here, BitsLeft is in the range [1..32] inclusive.
- R |= (CurWord & (~0U >> (32-BitsLeft))) << BitsInCurWord;
+ // Be careful here, BitsLeft is in the range [1..32]/[1..64] inclusive.
+ R |= uint32_t((CurWord & (word_t(~0ULL) >> (sizeof(word_t)*8-BitsLeft)))
+ << BitsInCurWord);
- // BitsLeft bits have just been used up from CurWord.
- if (BitsLeft != 32)
+ // BitsLeft bits have just been used up from CurWord. BitsLeft is in the
+ // range [1..32]/[1..64] so be careful how we shift.
+ if (BitsLeft != sizeof(word_t)*8)
CurWord >>= BitsLeft;
else
CurWord = 0;
- BitsInCurWord = 32-BitsLeft;
+ BitsInCurWord = sizeof(word_t)*8-BitsLeft;
return R;
}
}
}
- void SkipToWord() {
+private:
+ void SkipToFourByteBoundary() {
+ // If word_t is 64-bits and if we've read less than 32 bits, just dump
+ // the bits we have up to the next 32-bit boundary.
+ if (sizeof(word_t) > 4 &&
+ BitsInCurWord >= 32) {
+ CurWord >>= BitsInCurWord-32;
+ BitsInCurWord = 32;
+ return;
+ }
+
BitsInCurWord = 0;
CurWord = 0;
}
+public:
unsigned ReadCode() {
return Read(CurCodeSize);
// Read and ignore the codelen value. Since we are skipping this block, we
// don't care what code widths are used inside of it.
ReadVBR(bitc::CodeLenWidth);
- SkipToWord();
- unsigned NumWords = Read(bitc::BlockSizeWidth);
+ SkipToFourByteBoundary();
+ unsigned NumFourBytes = Read(bitc::BlockSizeWidth);
// Check that the block wasn't partially defined, and that the offset isn't
// bogus.
- size_t SkipTo = NextChar + NumWords*4;
- if (AtEndOfStream() || !canSkipToPos(SkipTo))
+ size_t SkipTo = GetCurrentBitNo() + NumFourBytes*4*8;
+ if (AtEndOfStream() || !canSkipToPos(SkipTo/8))
return true;
- NextChar = SkipTo;
+ JumpToBit(SkipTo);
return false;
}
// Block tail:
// [END_BLOCK, <align4bytes>]
- SkipToWord();
+ SkipToFourByteBoundary();
popBlockScope();
return false;
projects / oota-llvm.git / blobdiff