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Issue 2260: Small peephole optimization -- eliminate unnecessary POP_TOP /JUMP_FORWARD 1 pairs.

This commit is contained in:
Raymond Hettinger 2008-11-18 00:07:10 +00:00
parent a2a08fb932
commit e56131b60e
1 changed files with 10 additions and 0 deletions
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Python/peephole.c
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@ -430,6 +430,16 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
cumlc = 0;
break;
/* Replace POP_TOP JUMP_FORWARD 1 POP_TOP
with NOP NOP NOP NOP POP_TOP. */
case POP_TOP:
if (UNCONDITIONAL_JUMP(codestr[i+1]) &&
GETJUMPTGT(codestr, i+1) == i+5 &&
codestr[i+4] == POP_TOP &&
ISBASICBLOCK(blocks,i,4))
memset(codestr+i, NOP, 4);
break;
/* Try to fold tuples of constants (includes a case for lists
which are only used for "in" and "not in" tests).
Skip over BUILD_SEQN 1 UNPACK_SEQN 1.