diff options
Diffstat (limited to 'Python/compile.c')
| -rw-r--r-- | Python/compile.c | 54 |
1 files changed, 3 insertions, 51 deletions
diff --git a/Python/compile.c b/Python/compile.c index 787dfe3..24975b6 100644 --- a/Python/compile.c +++ b/Python/compile.c @@ -1748,9 +1748,6 @@ compiler_for(struct compiler *c, stmt_ty s) VISIT(c, expr, s->v.For.iter); ADDOP(c, GET_ITER); compiler_use_next_block(c, start); - /* for expressions must be traced on each iteration, - so we need to set an extra line number. */ - c->u->u_lineno_set = 0; ADDOP_JREL(c, FOR_ITER, cleanup); VISIT(c, expr, s->v.For.target); VISIT_SEQ(c, stmt, s->v.For.body); @@ -1796,9 +1793,6 @@ compiler_while(struct compiler *c, stmt_ty s) if (!compiler_push_fblock(c, LOOP, loop)) return 0; if (constant == -1) { - /* while expressions must be traced on each iteration, - so we need to set an extra line number. */ - c->u->u_lineno_set = 0; VISIT(c, expr, s->v.While.test); ADDOP_JABS(c, POP_JUMP_IF_FALSE, anchor); } @@ -3654,51 +3648,9 @@ blocksize(basicblock *b) return size; } -/* All about a_lnotab. - -c_lnotab is an array of unsigned bytes disguised as a Python string. -It is used to map bytecode offsets to source code line #s (when needed -for tracebacks). - -The array is conceptually a list of - (bytecode offset increment, line number increment) -pairs. The details are important and delicate, best illustrated by example: - - byte code offset source code line number - 0 1 - 6 2 - 50 7 - 350 307 - 361 308 - -The first trick is that these numbers aren't stored, only the increments -from one row to the next (this doesn't really work, but it's a start): - - 0, 1, 6, 1, 44, 5, 300, 300, 11, 1 - -The second trick is that an unsigned byte can't hold negative values, or -values larger than 255, so (a) there's a deep assumption that byte code -offsets and their corresponding line #s both increase monotonically, and (b) -if at least one column jumps by more than 255 from one row to the next, more -than one pair is written to the table. In case #b, there's no way to know -from looking at the table later how many were written. That's the delicate -part. A user of c_lnotab desiring to find the source line number -corresponding to a bytecode address A should do something like this - - lineno = addr = 0 - for addr_incr, line_incr in c_lnotab: - addr += addr_incr - if addr > A: - return lineno - lineno += line_incr - -In order for this to work, when the addr field increments by more than 255, -the line # increment in each pair generated must be 0 until the remaining addr -increment is < 256. So, in the example above, assemble_lnotab (it used -to be called com_set_lineno) should not (as was actually done until 2.2) -expand 300, 300 to 255, 255, 45, 45, - but to 255, 0, 45, 255, 0, 45. -*/ +/* Appends a pair to the end of the line number table, a_lnotab, representing + the instruction's bytecode offset and line number. See + Objects/lnotab_notes.txt for the description of the line number table. */ static int assemble_lnotab(struct assembler *a, struct instr *i) |