mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-08-03 16:39:00 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 8

SF bug 430991: wrong co_lnotab

Browse source 
Armin Rigo pointed out that the way the line-# table got built didn't work
for lines generating more than 255 bytes of bytecode.  Fixed as he
suggested, plus corresponding changes to pyassem.py, plus added some
long overdue docs about this subtle table to compile.c.

Bugfix candidate (line numbers may be off in tracebacks under -O).
This commit is contained in:
Tim Peters 2001-06-09 09:26:21 +00:00
parent eefa964932
commit 2a7f384122
4 changed files with 83 additions and 44 deletions
Download patch file Download diff file Expand all files Collapse all files

31
Tools/compiler/compiler/pyassem.py
View file

@ -613,16 +613,16 @@ def twobyte(val):
class LineAddrTable:
"""lnotab
This class builds the lnotab, which is undocumented but described
by com_set_lineno in compile.c. Here's an attempt at explanation:
This class builds the lnotab, which is documented in compile.c.
Here's a brief recap:
For each SET_LINENO instruction after the first one, two bytes are
added to lnotab. (In some cases, multiple two-byte entries are
added.) The first byte is the distance in bytes between the
instruction for the last SET_LINENO and the current SET_LINENO.
The second byte is offset in line numbers. If either offset is
greater than 255, multiple two-byte entries are added -- one entry
for each factor of 255.
greater than 255, multiple two-byte entries are added -- see
compile.c for the delicate details.
"""
def __init__(self):
@ -657,19 +657,16 @@ class LineAddrTable:
# compiler because it only generates a SET_LINENO instruction
# for the assignment.
if line > 0:
while addr > 0 or line > 0:
# write the values in 1-byte chunks that sum
# to desired value
trunc_addr = addr
trunc_line = line
if trunc_addr > 255:
trunc_addr = 255
if trunc_line > 255:
trunc_line = 255
self.lnotab.append(trunc_addr)
self.lnotab.append(trunc_line)
addr = addr - trunc_addr
line = line - trunc_line
push = self.lnotab.append
while addr > 255:
push(255); push(0)
addr -= 255
while line > 255:
push(addr); push(255)
line -= 255
addr = 0
if addr > 0 or line > 0:
push(addr); push(line)
self.lastline = lineno
self.lastoff = self.codeOffset