cpython

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Author	SHA1	Message	Date
Antoine Pitrou	7f14f0d8a0	Recorded merge of revisions 81032 via svnmerge from svn+ssh://pythondev@svn.python.org/python/branches/py3k ................ r81032 \| antoine.pitrou \| 2010-05-09 17:52:27 +0200 (dim., 09 mai 2010) \| 9 lines Recorded merge of revisions 81029 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r81029 \| antoine.pitrou \| 2010-05-09 16:46:46 +0200 (dim., 09 mai 2010) \| 3 lines Untabify C files. Will watch buildbots. ........ ................	16 years ago
Jeffrey Yasskin	9de7ec7868	http://bugs.python.org/issue4715 This patch by Antoine Pitrou optimizes the bytecode for conditional branches by merging the following "POP_TOP" instruction into the conditional jump. For example, the list comprehension "[x for x in l if not x]" produced the following bytecode: 1 0 BUILD_LIST 0 3 LOAD_FAST 0 (.0) >> 6 FOR_ITER 23 (to 32) 9 STORE_FAST 1 (x) 12 LOAD_FAST 1 (x) 15 JUMP_IF_TRUE 10 (to 28) 18 POP_TOP 19 LOAD_FAST 1 (x) 22 LIST_APPEND 2 25 JUMP_ABSOLUTE 6 >> 28 POP_TOP 29 JUMP_ABSOLUTE 6 >> 32 RETURN_VALUE but after the patch it produces the following bytecode: 1 0 BUILD_LIST 0 3 LOAD_FAST 0 (.0) >> 6 FOR_ITER 18 (to 27) 9 STORE_FAST 1 (x) 12 LOAD_FAST 1 (x) 15 POP_JUMP_IF_TRUE 6 18 LOAD_FAST 1 (x) 21 LIST_APPEND 2 24 JUMP_ABSOLUTE 6 >> 27 RETURN_VALUE Notice that not only the code is shorter, but the conditional jump (POP_JUMP_IF_TRUE) jumps right to the start of the loop instead of going through the JUMP_ABSOLUTE at the end. "continue" statements are helped similarly. Furthermore, the old jump opcodes (JUMP_IF_FALSE, JUMP_IF_TRUE) have been replaced by two new opcodes: - JUMP_IF_TRUE_OR_POP, which jumps if true and pops otherwise - JUMP_IF_FALSE_OR_POP, which jumps if false and pops otherwise	17 years ago
Antoine Pitrou	b52ec78baf	Issue #4753 : By enabling a configure option named '--with-computed-gotos' on compilers that support it (notably: gcc, SunPro, icc), the bytecode evaluation loop is compiled with a new dispatch mechanism which gives speedups of up to 20%, depending on the system, on various benchmarks.	17 years ago

Author

SHA1

Message

Date

Antoine Pitrou

7f14f0d8a0

Recorded merge of revisions 81032 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/branches/py3k

................
  r81032 | antoine.pitrou | 2010-05-09 17:52:27 +0200 (dim., 09 mai 2010) | 9 lines

  Recorded merge of revisions 81029 via svnmerge from
  svn+ssh://pythondev@svn.python.org/python/trunk

  ........
    r81029 | antoine.pitrou | 2010-05-09 16:46:46 +0200 (dim., 09 mai 2010) | 3 lines

    Untabify C files. Will watch buildbots.
  ........
................

16 years ago

Jeffrey Yasskin

9de7ec7868

http://bugs.python.org/issue4715

This patch by Antoine Pitrou optimizes the bytecode for conditional branches by
merging the following "POP_TOP" instruction into the conditional jump.  For
example, the list comprehension "[x for x in l if not x]" produced the
following bytecode:

  1           0 BUILD_LIST               0
              3 LOAD_FAST                0 (.0)
        >>    6 FOR_ITER                23 (to 32)
              9 STORE_FAST               1 (x)
             12 LOAD_FAST                1 (x)
             15 JUMP_IF_TRUE            10 (to 28)
             18 POP_TOP
             19 LOAD_FAST                1 (x)
             22 LIST_APPEND              2
             25 JUMP_ABSOLUTE            6
        >>   28 POP_TOP
             29 JUMP_ABSOLUTE            6
        >>   32 RETURN_VALUE

but after the patch it produces the following bytecode:

  1           0 BUILD_LIST               0
              3 LOAD_FAST                0 (.0)
        >>    6 FOR_ITER                18 (to 27)
              9 STORE_FAST               1 (x)
             12 LOAD_FAST                1 (x)
             15 POP_JUMP_IF_TRUE         6
             18 LOAD_FAST                1 (x)
             21 LIST_APPEND              2
             24 JUMP_ABSOLUTE            6
        >>   27 RETURN_VALUE

Notice that not only the code is shorter, but the conditional jump
(POP_JUMP_IF_TRUE) jumps right to the start of the loop instead of going through
the JUMP_ABSOLUTE at the end. "continue" statements are helped
similarly.

Furthermore, the old jump opcodes (JUMP_IF_FALSE, JUMP_IF_TRUE) have been
replaced by two new opcodes:
- JUMP_IF_TRUE_OR_POP, which jumps if true and pops otherwise
- JUMP_IF_FALSE_OR_POP, which jumps if false and pops otherwise

17 years ago

Antoine Pitrou

b52ec78baf

Issue #4753 : By enabling a configure option named '--with-computed-gotos'

on compilers that support it (notably: gcc, SunPro, icc), the bytecode
evaluation loop is compiled with a new dispatch mechanism which gives
speedups of up to 20%, depending on the system, on various benchmarks.

17 years ago

3 Commits (69e9727657dad167215b656de910d95cefe1ee45)