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GeezerVison is showing github.com — GH-100982: Add `COMPARE_AND_BRANCH` instruction by markshannon · Pull Request #100983 · python/cpython

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@markshannon

@markshannon markshannon commented Jan 12, 2023 •
edited by bedevere-bot
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  • Issue: Specialization of some instructions does not conform to PEP 659, and prevents PEP 669 #100982

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markshannon added 3 commits January 12, 2023 12:28
@markshannon
Add COMPARE_AND_BRANCH instruction
e5059b2
@markshannon
Update summarize stats script to handle both COMPAREs.
482777c
@markshannon
Remove attempted specialization of COMPARE_OP.
358393d
@markshannon
markshannon requested a review from iritkatriel as a code owner January 12, 2023 13:44
@bedevere-bot bedevere-bot added the awaiting core review label Jan 12, 2023
@bedevere-bot bedevere-bot mentioned this pull request Jan 12, 2023
Specialization of some instructions does not conform to PEP 659, and prevents PEP 669 #100982
Closed
@markshannon
Add news
c5c1764
iritkatriel
iritkatriel reviewed Jan 12, 2023
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Comment thread Lib/opcode.py
jrel_op('JUMP_BACKWARD', 140) # Number of words to skip (backwards)

def_op('COMPARE_AND_BRANCH', 141) # Comparison and jump
hascompare.append(141)

@iritkatriel iritkatriel Jan 12, 2023

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This opcode needs to be in hasjrel as well.

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@markshannon markshannon Jan 12, 2023

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The problem is that dis sees COMPARE_AND_BRANCH, then POP_JUMP_IF_. The POP_JUMP_IF_ is where we jump from.
So marking COMPARE_AND_BRANCH as a jump confuses dis, it thinks the operator is a jump offset. COMPARE_AND_BRANCH is effectively a superinstruction.

I could special case COMPARE_AND_BRANCH in dis, but I think it might be better to wait for proper support for longer instructions.

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Comment thread Lib/importlib/_bootstrap_external.py Resolved

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markshannon added 4 commits January 12, 2023 15:44
@markshannon
Document COMPARE_OP instruction.
944147c
@markshannon
Document the correct instruction
ef3fe45
@markshannon
Regenerate file
447f63e
@markshannon
Revert change to COMPARE_AND_BRANCH classification.
7d33508
iritkatriel
iritkatriel approved these changes Jan 16, 2023
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@bedevere-bot bedevere-bot added awaiting merge and removed awaiting core review labels Jan 16, 2023
iritkatriel
iritkatriel reviewed Jan 16, 2023
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Comment thread Python/specialize.c Resolved

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markshannon added 2 commits January 16, 2023 10:52
@markshannon
Avoid unused variable warning when NDEBUG is defined.
776ba54
@markshannon
Merge branch 'main' into compare-and-branch-instruction-2
5b01cc5
@markshannon
markshannon merged commit 7b14c2e into python:main Jan 16, 2023
@bedevere-bot bedevere-bot removed the awaiting merge label Jan 16, 2023
@oscarbenjamin oscarbenjamin mentioned this pull request Feb 26, 2023
Regression segfault under CPython 3.12a5 in the SymPy test suite #102250
Closed
@markshannon
markshannon deleted the compare-and-branch-instruction-2 branch September 26, 2023 12:53
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@iritkatriel iritkatriel iritkatriel approved these changes

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@markshannon @iritkatriel @bedevere-bot
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