Issue 42719: Eliminate NOPs in the assembler, by emitting zero-width entries in the line number table

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This issue has been migrated to GitHub: https://github.com/python/cpython/issues/86885

classification

Title:	Eliminate NOPs in the assembler, by emitting zero-width entries in the line number table
Type:	performance	Stage:	needs patch
Components:	Interpreter Core	Versions:	Python 3.10

process

Status:	open	Resolution:
Dependencies:		Superseder:
Assigned To:	Mark.Shannon	Nosy List:	Mark.Shannon
Priority:	normal	Keywords:

Created on 2020-12-22 14:08 by Mark.Shannon, last changed 2022-04-11 14:59 by admin.

Messages (1)
msg383590 - (view)	Author: Mark Shannon (Mark.Shannon) *	Date: 2020-12-22 14:08
This will require a change to the internal line number table format. PEP 626 requires all lines are traced, which makes handling of 'continue' and other jump-to-jumps inefficient if spread across multiple lines. In 3.9 many jump-to-jumps were eliminated, but PEP 626 requires that many are converted to a NOP. Zero-width line number table entries will allow us to eliminate most, if not all, remaining NOPs in the assembler.

msg383590 - (view)

Author: Mark Shannon (Mark.Shannon) * (Python committer)

Date: 2020-12-22 14:08

This will require a change to the internal line number table format.

PEP 626 requires all lines are traced, which makes handling of 'continue' and other jump-to-jumps inefficient if spread across multiple lines.

In 3.9 many jump-to-jumps were eliminated, but PEP 626 requires that many are converted to a NOP. Zero-width line number table entries will allow us to eliminate most, if not all, remaining NOPs in the assembler.

History
Date	User	Action	Args
2022-04-11 14:59:39	admin	set	github: 86885
2020-12-22 14:08:13	Mark.Shannon	create