Thanks to visit codestin.com
Credit goes to github.com

Skip to content

gh-96455: update example in exception_handling_notes.txt to the 3.11RC bytecode #96456

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Sep 1, 2022
Merged

gh-96455: update example in exception_handling_notes.txt to the 3.11RC bytecode #96456

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
12a8503
gh-96455: update example in exception_handling_notes.txt to the 3.11R…
iritkatriel Aug 31, 2022
dbd4ebd
update one more place
iritkatriel Aug 31, 2022
abafa12
put back note on the code being from 3.11. Fix punctuation.
iritkatriel Sep 1, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
53 changes: 28 additions & 25 deletions Objects/exception_handling_notes.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -43,33 +43,36 @@ SETUP_FINALLY and POP_BLOCK.
In 3.11, the SETUP_FINALLY and POP_BLOCK are eliminated, replaced with
a table to determine where to jump to when an exception is raised.

2 0 NOP

3 2 LOAD_GLOBAL 0 (g)
4 LOAD_CONST 1 (0)
6 CALL_NO_KW 1
8 POP_TOP
10 LOAD_CONST 0 (None)
12 RETURN_VALUE
>> 14 PUSH_EXC_INFO

4 16 POP_TOP
18 POP_TOP
20 POP_TOP

5 22 POP_EXCEPT
24 LOAD_CONST 2 ('fail')
26 RETURN_VALUE
>> 28 POP_EXCEPT_AND_RERAISE
1 0 RESUME 0

2 2 NOP

3 4 LOAD_GLOBAL 1 (NULL + g)
16 LOAD_CONST 1 (0)
18 PRECALL 1
22 CALL 1
32 POP_TOP
34 LOAD_CONST 0 (None)
36 RETURN_VALUE
>> 38 PUSH_EXC_INFO

4 40 POP_TOP

5 42 POP_EXCEPT
44 LOAD_CONST 2 ('fail')
46 RETURN_VALUE
>> 48 COPY 3
50 POP_EXCEPT
52 RERAISE 1
ExceptionTable:
2 to 8 -> 14 [0]
14 to 20 -> 28 [3] lasti
4 to 32 -> 38 [0]
38 to 40 -> 48 [1] lasti

(Note this code is from an early 3.11 alpha, the NOP may well have be removed before release).
(Note this code is from 3.11, later versions may have slightly different bytecode.)

If an instruction raises an exception then its offset is used to find the target to jump to.
For example, the CALL_NO_KW at offset 6, falls into the range 2 to 8.
So, if g() raises an exception, then control jumps to offset 14.
For example, the CALL at offset 22, falls into the range 4 to 32.
So, if g() raises an exception, then control jumps to offset 38.


Unwinding
Expand All @@ -84,9 +87,9 @@ This information is stored in the exception table, described below.
If there is no relevant entry, the exception bubbles up to the caller.

If there is an entry, then:
1. pop values from the stack until it matches the stack depth for the handler,
1. pop values from the stack until it matches the stack depth for the handler.
2. if 'lasti' is true, then push the offset that the exception was raised at.
3. push the exception to the stack as three values: traceback, value, type,
3. push the exception to the stack.
4. jump to the target offset and resume execution.


Expand Down