[Bug 2064539] Re: Revert back frame pointers for ppc64el (remove -fno-omit-framepointer)

[Simon Chopin]

** Also affects: glibc (Ubuntu)
   Importance: Undecided
       Status: New

** Also affects: dpkg (Ubuntu Noble)
   Importance: Undecided
       Status: New

** Also affects: glibc (Ubuntu Noble)
   Importance: Undecided
       Status: New

** Also affects: dpkg (Ubuntu Oracular)
   Importance: Undecided
       Status: New

** Also affects: glibc (Ubuntu Oracular)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/2064539

Title:
  Revert back frame pointers for ppc64el (remove -fno-omit-framepointer)

Status in The Ubuntu-power-systems project:
  New
Status in dpkg package in Ubuntu:
  New
Status in glibc package in Ubuntu:
  New
Status in dpkg source package in Noble:
  New
Status in glibc source package in Noble:
  New
Status in dpkg source package in Oracular:
  New
Status in glibc source package in Oracular:
  New

Bug description:
  Power's Linux ABIs all require an explicit call chain be stored on the call stack frames which are all accessible via the stack pointer.
  Therefore, having a (soft/simulated) frame pointer does not improve backtraces at all on Power.

  However, forcing a frame pointer via the -fno-omit-frame-pointer option negatively affects performance for multiple reasons: extra prologue/epilogue overhead and fewer shrink-wrapping opportunities.
  Given -fno-omit-frame-pointer does not provide any improvements (backtraces or otherwise) and only reduces performance, -fno-omit-frame-pointers should not be used on Power.

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