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  1. RHEL
  2. RHEL-1063

glibc: Add additional math IFUNCs on x86-64

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      0ccc7153ccd8fbecefb0793a65cd5a85cdb099fc
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    • rhel-pt-c-libs
    • ssg_platform_tools
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    • Red Hat Enterprise Linux
    • PT C Libraries 2026 S01
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      eu-readelf --symbols=.dynsym shows IFUNCs for the named functions, and performance of RHEL 9 glibc matches that of a glibc rebuild with -march=x86-64-v3.

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      eu-readelf --symbols=.dynsym shows IFUNCs for the named functions, and performance of RHEL 9 glibc matches that of a glibc rebuild with -march=x86-64-v3 .
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    • x86_64
    • Linux
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      Performance testing indicates that we see some potential for benchmark improvement if we add variants of log2, asinh, atanh, sinh, tanh.

      These changes would look similar to this one for log2f:

      commit 5c7adbd8eded546eb6e17a82f5ab3b35def47f38
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Sun Oct 22 08:06:46 2017 -0700

    x86-64: Add log2f with FMA
    
    For workload-spec2017.wrf, on Skylake, it improves performance by:
    
                               Before            After     Improvement
    reciprocal-throughput      16.5937          14.0789       17%
    latency                    41.7755          35.3586       18%
    
            * sysdeps/x86_64/fpu/multiarch/Makefile (libm-sysdep_routines):
            Add e_log2f-fma.
            (CFLAGS-e_log2f-fma.c): New.
            * sysdeps/x86_64/fpu/multiarch/e_log2f-fma.c: New file.
            * sysdeps/x86_64/fpu/multiarch/e_log2f.c: Likewise.

      Acceptance Criteria:
      eu-readelf --symbols=.dynsym shows IFUNCs for the named functions, and performance of RHEL 9 glibc matches that of a glibc rebuild with -march=x86-64-v3.

              Unassigned Unassigned
              fweimer@redhat.com Florian Weimer
              Platform Tools - Libraries Bot Platform Tools - Libraries Bot
              qe-baseos-tools-bugs@redhat.com qe-baseos-tools-bugs@redhat.com qe-baseos-tools-bugs@redhat.com qe-baseos-tools-bugs@redhat.com
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