mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-08-31 05:58:33 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 7

bpo-38115: Deal with invalid bytecode offsets in lnotab (GH-16079)

Browse source 
Document that lnotab can contain invalid bytecode offsets (because of
terrible reasons that are difficult to fix). Make dis.findlinestarts()
ignore invalid offsets in lnotab. All other uses of lnotab in CPython
(various reimplementations of addr2line or line2addr in Python, C and gdb)
already ignore this, because they take an address to look for, instead.

Add tests for the result of dis.findlinestarts() on wacky constructs in
test_peepholer.py, because it's the easiest place to add them.
This commit is contained in:
T. Wouters 2019-09-28 16:49:15 +02:00 • committed by Gregory P. Smith
parent 7774d7831e
commit c8165036f3
4 changed files with 77 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

4
Objects/lnotab_notes.txt
View file

@ -3,7 +3,9 @@ All about co_lnotab, the line number table.
Code objects store a field named co_lnotab. This is an array of unsigned bytes
disguised as a Python bytes object. It is used to map bytecode offsets to
source code line #s for tracebacks and to identify line number boundaries for
line tracing.
line tracing. Because of internals of the peephole optimizer, it's possible
for lnotab to contain bytecode offsets that are no longer valid (for example
if the optimizer removed the last line in a function).
The array is conceptually a compressed list of
(bytecode offset increment, line number increment)