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co_lnotab supports negative line number delta

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Issue #26107: The format of the co_lnotab attribute of code objects changes to
support negative line number delta.

Changes:

* assemble_lnotab(): if line number delta is less than -128 or greater than
  127, emit multiple (offset_delta, lineno_delta) in co_lnotab
* update functions decoding co_lnotab to use signed 8-bit integers

  - dis.findlinestarts()
  - PyCode_Addr2Line()
  - _PyCode_CheckLineNumber()
  - frame_setlineno()

* update lnotab_notes.txt
* increase importlib MAGIC_NUMBER to 3361
* document the change in What's New in Python 3.6
* cleanup also PyCode_Optimize() to use better variable names
This commit is contained in:
Victor Stinner 2016-01-20 12:16:21 +01:00
parent 316fcc867b
commit f3914eb16d
11 changed files with 203 additions and 161 deletions
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25
Python/compile.c
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@ -4452,7 +4452,6 @@ assemble_lnotab(struct assembler *a, struct instr *i)
d_lineno = i->i_lineno - a->a_lineno;
assert(d_bytecode >= 0);
assert(d_lineno >= 0);
if(d_bytecode == 0 && d_lineno == 0)
return 1;
@ -4482,9 +4481,21 @@ assemble_lnotab(struct assembler *a, struct instr *i)
d_bytecode -= ncodes * 255;
a->a_lnotab_off += ncodes * 2;
}
assert(d_bytecode <= 255);
if (d_lineno > 255) {
int j, nbytes, ncodes = d_lineno / 255;
assert(0 <= d_bytecode && d_bytecode <= 255);
if (d_lineno < -128 || 127 < d_lineno) {
int j, nbytes, ncodes, k;
if (d_lineno < 0) {
k = -128;
/* use division on positive numbers */
ncodes = (-d_lineno) / 128;
}
else {
k = 127;
ncodes = d_lineno / 127;
}
d_lineno -= ncodes * k;
assert(ncodes >= 1);
nbytes = a->a_lnotab_off + 2 * ncodes;
len = PyBytes_GET_SIZE(a->a_lnotab);
if (nbytes >= len) {
@ -4502,15 +4513,15 @@ assemble_lnotab(struct assembler *a, struct instr *i)
lnotab = (unsigned char *)
PyBytes_AS_STRING(a->a_lnotab) + a->a_lnotab_off;
*lnotab++ = d_bytecode;
*lnotab++ = 255;
*lnotab++ = k;
d_bytecode = 0;
for (j = 1; j < ncodes; j++) {
*lnotab++ = 0;
*lnotab++ = 255;
*lnotab++ = k;
}
d_lineno -= ncodes * 255;
a->a_lnotab_off += ncodes * 2;
}
assert(-128 <= d_lineno && d_lineno <= 127);
len = PyBytes_GET_SIZE(a->a_lnotab);
if (a->a_lnotab_off + 2 >= len) {