Landing: a575c5191691

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Project / Subsystem

gcc / libstdc++

Date

2026-04-29

Author

Alexandre Oliva

Commit

a575c519169184bef374009c8ed6e805ebac609a

Source

github

Perf win

Breaking

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All attributes

project: gcc
subsystem: libstdc++
patch_id: —
commit_hash: a575c519169184bef374009c8ed6e805ebac609a
source_type: github
headline: Libstdc++: Map 64-bit long double to double on SSE
tldr: libstdc++ now maps 64-bit `long double` to `double` on SSE when using the `-mlong-double-64` option.
author: Alexandre Oliva
outcome: committed
performance_win: false
breaking_change: false
series_id: —
series_parts: []
tags: • libstdc++
• simd
• x86
• long double
• abi
discussion_id_link: —
bugzilla_pr: —
url: https://github.com/gcc-mirror/gcc/commit/a575c519169184bef374009c8ed6e805ebac609a
date: 2026-04-29T00:00:00.000Z

When compiling for x86 with the -mlong-double-64 option, where long double is ABI-compatible with double, this commit ensures that the __intrinsic_type used by the libstdc++ SIMD extensions is a vector of double. This mapping ensures correct behavior and ABI compliance for SIMD operations involving long double when it is configured to be 64-bit.