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CT_00_038 - mem* and str* -- inline expansion in GLIBC implementation

CT_00_038 - mem* and str* -- inline expansion in GLIBC implementation

Nov 06, 2024

About

Glibc provides generic versions of all the relevant routines and needs both scalar and vector implementations with automatic selection via ifuncs.

 

 

 

 

Stakeholders/Partners

RISE:

Ventana: Jeff & Robin

Rivos: Palmer & Sergei

 

External:

                    VRULL: Christoph Muller

                    EMBECOSM: Joern Rennecke

 

 

Dependencies

 

Status

Development

COMPLETE

 

Development Timeline

1H2024

 

Upstreaming

IN PROGRESS

 

Upstream Version

 

glibc-2.41 (target)
Winter 2024

 

 

 

Contacts

Jeff Law (Ventana)

 

Dependencies

None

 

 

Updates

Nov 6, 2024 

  • Vectorized memset accepted by glibc project, pending one trivial fix.

  • Should be able to stamp out the rest trivially now

Oct 9, 2024 

  • Ventana has changes which wire up the vector str*/mem* routines from SiFive & Rivos as well as scalar versions of VRULL into ifunc/hwprobe framework

  • Tested on BPI & QEMU to verify we get into the appropriate routine based on the result of the hwprobe query

    • Did expose minor bugs in the VRULL scalar implementations which have since been fixed

  • Upstream doesn't want the str* scalar implementations in their current form

    • Rather than full raw assembly routines, use C versions with the magic twiddles to enable using orc.b and such

    • Not currently planning to implement this (focused on vector), but someone else certainly could

Jun 29, 2024

  • GLIBC effort broken out into a distinct 2H2024 work item