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On i386 and x86-64, just do unaligned loads 

instead of assembling from bytes.  This speeds up -Eonly PTH reading 
of cocoa.h by about 2ms, which is 4.2%.

llvm-svn: 62447
This commit is contained in:
Chris Lattner 2009-01-18 02:19:16 +00:00
parent e70cde134e
commit 9cdd877436
1 changed files with 20 additions and 0 deletions
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20
clang/lib/Lex/PTHLexer.cpp
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@ -38,25 +38,45 @@ static inline uint8_t Read8(const unsigned char *&Data) {
}
static inline uint16_t Read16(const unsigned char *&Data) {
// Targets that directly support unaligned little-endian 16-bit loads can just
// use them.
#if defined(__i386__) || defined(__x86_64__)
uint16_t V = *((uint16_t*)Data);
#else
uint16_t V = ((uint16_t)Data[0] << 0) |
((uint16_t)Data[1] << 8);
#endif
Data += 2;
return V;
}
static inline uint32_t Read24(const unsigned char *&Data) {
// Targets that directly support unaligned little-endian 16-bit loads can just
// use them.
#if defined(__i386__) || defined(__x86_64__)
uint32_t V = ((uint16_t*)Data)[0] |
((uint32_t)Data[2] << 16);
#else
uint32_t V = ((uint32_t)Data[0] << 0) |
((uint32_t)Data[1] << 8) |
((uint32_t)Data[2] << 16);
#endif
Data += 3;
return V;
}
static inline uint32_t Read32(const unsigned char *&Data) {
// Targets that directly support unaligned little-endian 32-bit loads can just
// use them.
#if defined(__i386__) || defined(__x86_64__)
uint32_t V = *((uint32_t*)Data);
#else
uint32_t V = ((uint32_t)Data[0] << 0) |
((uint32_t)Data[1] << 8) |
((uint32_t)Data[2] << 16) |
((uint32_t)Data[3] << 24);
#endif
Data += 4;
return V;
}