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Simplify and future proof NOP counting in the peepholer.

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No longer assumes that the input is NOP free.
This commit is contained in:
Raymond Hettinger 2004-11-01 15:19:11 +00:00
parent 4a8d851910
commit 099ecfbec9
1 changed files with 6 additions and 13 deletions
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19
Python/compile.c
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@ -536,8 +536,7 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
goto exitUnchanged; goto exitUnchanged;
assert(PyList_Check(consts)); assert(PyList_Check(consts));
for (i=0, nops=0 ; i<codelen ; i += CODESIZE(codestr[i])) { for (i=0 ; i<codelen ; i += CODESIZE(codestr[i])) {
addrmap[i] = i - nops;
opcode = codestr[i]; opcode = codestr[i];
lastlc = cumlc; lastlc = cumlc;
@ -560,7 +559,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
SETARG(codestr, i, j); SETARG(codestr, i, j);
codestr[i+3] = POP_TOP; codestr[i+3] = POP_TOP;
codestr[i+4] = NOP; codestr[i+4] = NOP;
nops++;
break; break;
/* not a is b --> a is not b /* not a is b --> a is not b
@ -575,7 +573,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
continue; continue;
SETARG(codestr, i, (j^1)); SETARG(codestr, i, (j^1));
codestr[i+3] = NOP; codestr[i+3] = NOP;
nops++;
break; break;
/* Replace LOAD_GLOBAL/LOAD_NAME None with LOAD_CONST None */ /* Replace LOAD_GLOBAL/LOAD_NAME None with LOAD_CONST None */
@ -604,7 +601,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
!PyObject_IsTrue(PyList_GET_ITEM(consts, j))) !PyObject_IsTrue(PyList_GET_ITEM(consts, j)))
continue; continue;
memset(codestr+i, NOP, 7); memset(codestr+i, NOP, 7);
nops += 7;
break; break;
/* Try to fold tuples of constants. /* Try to fold tuples of constants.
@ -619,7 +615,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
codestr[h] == LOAD_CONST && codestr[h] == LOAD_CONST &&
ISBASICBLOCK(blocks, h, 3*(j+1)) && ISBASICBLOCK(blocks, h, 3*(j+1)) &&
tuple_of_constants(&codestr[h], j, consts)) { tuple_of_constants(&codestr[h], j, consts)) {
nops += 3 * j;
break; break;
} }
/* Intentional fallthrough */ /* Intentional fallthrough */
@ -631,16 +626,13 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
continue; continue;
if (j == 1) { if (j == 1) {
memset(codestr+i, NOP, 6); memset(codestr+i, NOP, 6);
nops += 6;
} else if (j == 2) { } else if (j == 2) {
codestr[i] = ROT_TWO; codestr[i] = ROT_TWO;
memset(codestr+i+1, NOP, 5); memset(codestr+i+1, NOP, 5);
nops += 5;
} else if (j == 3) { } else if (j == 3) {
codestr[i] = ROT_THREE; codestr[i] = ROT_THREE;
codestr[i+1] = ROT_TWO; codestr[i+1] = ROT_TWO;
memset(codestr+i+2, NOP, 4); memset(codestr+i+2, NOP, 4);
nops += 4;
} }
break; break;
@ -704,12 +696,16 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
!ISBASICBLOCK(blocks,i,5)) !ISBASICBLOCK(blocks,i,5))
continue; continue;
memset(codestr+i+1, NOP, 4); memset(codestr+i+1, NOP, 4);
nops += 4;
break; break;
} }
} }
/* Fixup linenotab */ /* Fixup linenotab */
for (i=0, nops=0 ; i<codelen ; i += CODESIZE(codestr[i])) {
addrmap[i] = i - nops;
if (codestr[i] == NOP)
nops++;
}
cum_orig_line = 0; cum_orig_line = 0;
last_line = 0; last_line = 0;
for (i=0 ; i < tabsiz ; i+=2) { for (i=0 ; i < tabsiz ; i+=2) {
@ -749,9 +745,6 @@ optimize_code(PyObject *code, PyObject* consts, PyObject *names, PyObject *linen
while (adj--) while (adj--)
codestr[h++] = codestr[i++]; codestr[h++] = codestr[i++];
} }
/* The following assertion detects the presence of NOPs in the input
bytecode. The compiler never produces NOPs so far; if one day it
does, the way 'nops' is counted above must be changed. */
assert(h + nops == codelen); assert(h + nops == codelen);
code = PyString_FromStringAndSize((char *)codestr, h); code = PyString_FromStringAndSize((char *)codestr, h);