Landing: 353bf917a996

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Project / Subsystem

gcc / gcc/i386

Date

2026-09-02

Author

Haochen Jiang

Commit

353bf917a996e5246e7aa0c4c223fc4359339626

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: gcc/i386
patch_id: —
commit_hash: 353bf917a996e5246e7aa0c4c223fc4359339626
source_type: github
headline: Add tmm as fake register
tldr: Introduces a 'fake' TMM register to facilitate future register allocation for ACE ISAs.
author: Haochen Jiang
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • gcc
• i386
• ACE
• register allocation
• compiler internals
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/353bf917a996e5246e7aa0c4c223fc4359339626
date: 2026-09-02T00:00:00.000Z

This commit introduces a conceptual ‘TMM’ register within GCC’s i386 backend to prepare for future register allocation in ACE ISAs. While full register allocation is not yet implemented due to spill management complexities, this ‘fake’ register allows the compiler to understand instruction dependencies better than using inline assembly. It ensures that users can pass TMM register numbers, enabling user-driven allocation which is suitable as TMM acts as an accumulation unit.