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9 Commits

Author SHA1 Message Date
Raymond Hettinger fd7ed407d7 Give meaning to the oparg for BUILD_MAP: estimated size of the dictionary. 
Allows dictionaries to be pre-sized (upto 255 elements) saving time lost
to re-sizes with their attendant mallocs and re-insertions.

Has zero effect on small dictionaries (5 elements or fewer), a slight
benefit for dicts upto 22 elements (because they had to resize once
anyway), and more benefit for dicts upto 255 elements (saving multiple
resizes during the build-up and reducing the number of collisions on
the first insertions).  Beyond 255 elements, there is no addional benefit.
 2007-12-18 21:24:09 +00:00
Raymond Hettinger effde12f5f Speed-up dictionary constructor by about 10%. 
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
 2007-12-18 18:26:18 +00:00
Guido van Rossum c2e20744b2 PEP 343 -- the with-statement. 
This was started by Mike Bland and completed by Guido
(with help from Neal).

This still needs a __future__ statement added;
Thomas is working on Michael's patch for that aspect.

There's a small amount of code cleanup and refactoring
in ast.c, compile.c and ceval.c (I fixed the lltrace
behavior when EXT_POP is used -- however I had to make
lltrace a static global).
 2006-02-27 22:32:47 +00:00
Raymond Hettinger 9c18e81fb2 Install two code generation optimizations that depend on NOP. 
Reduces the cost of "not" to almost zero.
 2004-06-21 16:31:15 +00:00
Raymond Hettinger dd80f76265 SF patch #910929: Optimize list comprehensions 
Add a new opcode, LIST_APPEND, and apply it to the code generation for
list comprehensions.  Reduces the per-loop overhead by about a third.
 2004-03-07 07:31:06 +00:00
Walter Dörwald 70a6b49821 Replace backticks with repr() or "%r" 
From SF patch #852334.
 2004-02-12 17:35:32 +00:00
Raymond Hettinger f4cf76dd5e Revert the previous enhancement to the bytecode optimizer. 
The additional code complexity and new NOP opcode were not worth it.
 2003-04-24 05:45:23 +00:00
Raymond Hettinger 060641d511 Improved the bytecode optimizer. 
* Can now test for basic blocks.
* Optimize inverted comparisions.
* Optimize unary_not followed by a conditional jump.
* Added a new opcode, NOP, to keep code size constant.
* Applied NOP to previous transformations where appropriate.

Note, the NOP would not be necessary if other functions were
added to re-target jump addresses and update the co_lnotab mapping.
That would yield slightly faster and cleaner bytecode at the
expense of optimizer simplicity and of keeping it decoupled
from the line-numbering structure.
 2003-04-22 06:49:11 +00:00
Skip Montanaro 3249ccd06a new opcode module - extract opcode definitions from dis.py - eventually 
should be generated automatically
 2003-02-27 21:27:52 +00:00