Landing: 83880beea997
Project / Subsystem
gcc / i386
Date
2026-07-01
Author
Roger Sayle
Commit
83880beea997e435f56de9cab08929e213732025
Source
github
Perf win
Yes
Breaking
No
All attributes
- project
- gcc
- subsystem
- i386
- patch_id
- —
- commit_hash
- 83880beea997e435f56de9cab08929e213732025
- source_type
- github
- headline
- i386: Improve x86 Scalar-To-Vector conversion for zero-extended memory loads
- tldr
- Optimizes Scalar-To-Vector (STV) conversion by recognizing that loading a 32-bit value into an SSE register naturally zero-extends it to 64 bits.
- author
- Roger Sayle
- outcome
- committed
- performance_win
- true
- breaking_change
- false
- series_id
- —
- series_parts
- []
- tags
-
- • i386
- • sse2
- • optimization
- • vectorization
- discussion_id_link
- —
- bugzilla_pr
- —
- date
- 2026-07-01T00:00:00.000Z
This patch enhances the i386 backend’s Scalar-To-Vector (STV) conversion by allowing it to recognize and optimize patterns where a 32-bit memory value is zero-extended to a 64-bit value using SSE registers. Loading a 32-bit value into an SSE register automatically clears the upper bits, effectively performing a zero-extension. This transformation replaces multiple instructions with a single SSE load and manipulation, improving code density and potentially performance.