2011/1/31 Antoine Pitrou <solip...@pitrou.net> > On Mon, 31 Jan 2011 13:28:39 +0100 > "Jurjen N.E. Bos" <jurjen....@hetnet.nl> wrote: > > I just did it: my first python source code hack. > > I replaced the NEXTARG and PEEKARG macros in ceval.c using a cast to > > short pointer, and lo and behold, a crude measurement indicates one > > to two percent speed increase. > > That isn't much, but it is virtually for free! > > > > Here are the macro's I used: > > #define NEXTARG() (next_instr +=2, *(short*)&next_instr[-2]) > > #define PEEKARG() (*(short*)&next_instr[1]) > > Some architectures forbid unaligned access, so this can't be used as-is. > > Regards > > Antoine. > > WPython already addressed it ( http://code.google.com/p/wpython2/source/browse/Python/ceval.c?repo=wpython11):
#ifdef WORDS_BIGENDIAN #define NEXTOPCODE() oparg = *next_instr++; \ opcode = oparg >> 8; oparg &= 0xff #else #define NEXTOPCODE() oparg = *next_instr++; \ opcode = oparg & 0xff; oparg >>= 8 #endif Shorts alignament is also guaranted due to wordcodes ( http://wpython2.googlecode.com/files/Beyond%20Bytecode%20-%20A%20Wordcode-based%20Python.pdfpag.12). Cesare
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