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Update the peephole optimizer to remove more dead code (jumps after returns)

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and inline jumps to returns.
This commit is contained in:
Neal Norwitz 2006-10-14 21:33:38 +00:00
parent 5a72372329
commit cbeb687c68
4 changed files with 55 additions and 5 deletions
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19
Python/peephole.c
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@ -523,6 +523,13 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
case SETUP_EXCEPT:
case SETUP_FINALLY:
tgt = GETJUMPTGT(codestr, i);
/* Replace JUMP_* to a RETURN into just a RETURN */
if (UNCONDITIONAL_JUMP(opcode) &&
codestr[tgt] == RETURN_VALUE) {
codestr[i] = RETURN_VALUE;
memset(codestr+i+1, NOP, 2);
continue;
}
if (!UNCONDITIONAL_JUMP(codestr[tgt]))
continue;
tgttgt = GETJUMPTGT(codestr, tgt);
@ -540,12 +547,16 @@ PyCode_Optimize(PyObject *code, PyObject* consts, PyObject *names,
goto exitUnchanged;
/* Replace RETURN LOAD_CONST None RETURN with just RETURN */
/* Remove unreachable JUMPs after RETURN */
case RETURN_VALUE:
if (i+4 >= codelen ||
codestr[i+4] != RETURN_VALUE ||
!ISBASICBLOCK(blocks,i,5))
if (i+4 >= codelen)
continue;
memset(codestr+i+1, NOP, 4);
if (codestr[i+4] == RETURN_VALUE &&
ISBASICBLOCK(blocks,i,5))
memset(codestr+i+1, NOP, 4);
else if (UNCONDITIONAL_JUMP(codestr[i+1]) &&
ISBASICBLOCK(blocks,i,4))
memset(codestr+i+1, NOP, 3);
break;
}
}