Landing: 02cc188d3d9f

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Project / Subsystem

gcc / libgomp, amdgcn

Date

2026-04-20

Author

Andrew Stubbs

Commit

02cc188d3d9f14975c8285678f937a1ba79bedeb

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: libgomp, amdgcn
patch_id: —
commit_hash: 02cc188d3d9f14975c8285678f937a1ba79bedeb
source_type: github
headline: libgomp, amdgcn: Ensure s_memrealtime uses SGPRs
tldr: AMD GCN time function now correctly uses special function registers (SGPRs) for stability.
author: Andrew Stubbs
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • amd
• gpu
• libgomp
• assembly
• performance
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/02cc188d3d9f14975c8285678f937a1ba79bedeb
date: 2026-04-20T00:00:00.000Z

The s_memrealtime intrinsic within libgomp’s AMD GCN backend was using a generic ‘r’ register constraint. This could lead to instability, especially in SIMT execution, as it might only select a compatible register by chance. This commit changes the constraint to the more specific Sg (Special General Purpose Register), ensuring that the intrinsic reliably uses SGPRs, thereby improving the stability and correctness of time-related functions on AMD GPUs.