From f15674c680730c652a37a16a5d3f3ff429b0c308 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sun, 18 Jan 2009 02:19:16 +0000 Subject: [PATCH] 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%. git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62447 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Lex/PTHLexer.cpp | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/lib/Lex/PTHLexer.cpp b/lib/Lex/PTHLexer.cpp index 8d06ac6bbc..92c5e8815b 100644 --- a/lib/Lex/PTHLexer.cpp +++ b/lib/Lex/PTHLexer.cpp @@ -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; } -- 2.40.0