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Speed-up dictionary constructor by about 10%.

Browse source 
New opcode, STORE_MAP saves the compiler from awkward stack manipulations
and specializes for dicts using PyDict_SetItem instead of PyObject_SetItem.

Old disassembly:
              0 BUILD_MAP                0
              3 DUP_TOP
              4 LOAD_CONST               1 (1)
              7 ROT_TWO
              8 LOAD_CONST               2 ('x')
             11 STORE_SUBSCR
             12 DUP_TOP
             13 LOAD_CONST               3 (2)
             16 ROT_TWO
             17 LOAD_CONST               4 ('y')
             20 STORE_SUBSCR

New disassembly:
              0 BUILD_MAP                0
              3 LOAD_CONST               1 (1)
              6 LOAD_CONST               2 ('x')
              9 STORE_MAP
             10 LOAD_CONST               3 (2)
             13 LOAD_CONST               4 ('y')
             16 STORE_MAP
This commit is contained in:
Raymond Hettinger 2007-12-18 18:26:18 +00:00
parent eb103b3577
commit effde12f5f
5 changed files with 19 additions and 5 deletions
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4
Python/import.c
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@ -66,10 +66,10 @@ extern time_t PyOS_GetLastModificationTime(char *, FILE *);
Python 2.5c1: 62121 (fix wrong lnotab with for loops and
storing constants that should have been removed)
Python 2.5c2: 62131 (fix wrong code: for x, in ... in listcomp/genexp)
Python 2.6a0: 62141 (peephole optimizations)
Python 2.6a0: 62151 (peephole optimizations and STORE_MAP opcode)
.
*/
#define MAGIC (62141 | ((long)'\r'<<16) | ((long)'\n'<<24))
#define MAGIC (62151 | ((long)'\r'<<16) | ((long)'\n'<<24))
/* Magic word as global; note that _PyImport_Init() can change the
value of this global to accommodate for alterations of how the