[Bug 1793786] [NEW] libc6 2.27 lacks sse2 optimized strstr()

[Paul Stephen Borile]

Public bug reported:

Looks like code using strstr() and libc-2.27 is running 4 times slower
than was with libc-2.23. Having a look at profiled code executed in
various moments show different versions of strstr :

- libc-2.27.so: strstr.c, str-two-way.h - this is current version ubuntu
18.04.1

Same code, profiled March 13, 2018 :

- libc-2.23.so: strstr-sse2-unaligned.S

Is the removal of sse2 optimized code from strstr() an error of some kind ?
Best
-Paul

** Affects: glibc (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1793786

Title:
  libc6 2.27 lacks sse2 optimized strstr()

Status in glibc package in Ubuntu:
  New

Bug description:
  Looks like code using strstr() and libc-2.27 is running 4 times slower
  than was with libc-2.23. Having a look at profiled code executed in
  various moments show different versions of strstr :

  - libc-2.27.so: strstr.c, str-two-way.h - this is current version
  ubuntu 18.04.1

  Same code, profiled March 13, 2018 :

  - libc-2.23.so: strstr-sse2-unaligned.S

  Is the removal of sse2 optimized code from strstr() an error of some kind ?
  Best
  -Paul

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