[Bug target/99888] Add powerpc ELFv2 support for -fpatchable-function-entry*

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99888

--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Kewen Lin <linkw@gcc.gnu.org>:

https://gcc.gnu.org/g:c23b5006d3ffeda1a9edf5fd817765a6da3696ca

commit r13-2984-gc23b5006d3ffeda1a9edf5fd817765a6da3696ca
Author: Kewen Lin <linkw@linux.ibm.com>
Date:   Fri Sep 30 07:16:49 2022 -0500

    rs6000: Rework ELFv2 support for -fpatchable-function-entry* [PR99888]

    As PR99888 and its related show, the current support for
    -fpatchable-function-entry on powerpc ELFv2 doesn't work
    well with global entry existence.  For example, with one
    command line option -fpatchable-function-entry=3,2, it got
    below w/o this patch:

      .LPFE1:
              nop
              nop
              .type   foo, @function
      foo:
              nop
      .LFB0:
              .cfi_startproc
      .LCF0:
      0:      addis 2,12,.TOC.-.LCF0@ha
              addi 2,2,.TOC.-.LCF0@l
              .localentry     foo,.-foo

    , the assembly is unexpected since the patched nops have
    no effects when being entered from local entry.

    This patch is to update the nops patched before and after
    local entry, it looks like:

              .type   foo, @function
      foo:
      .LFB0:
              .cfi_startproc
      .LCF0:
      0:      addis 2,12,.TOC.-.LCF0@ha
              addi 2,2,.TOC.-.LCF0@l
              nop
              nop
              .localentry     foo,.-foo
              nop

            PR target/99888
            PR target/105649

    gcc/ChangeLog:

            * doc/invoke.texi (option -fpatchable-function-entry): Adjust the
            documentation for PowerPC ELFv2 ABI dual entry points.
            * config/rs6000/rs6000-internal.h
            (rs6000_print_patchable_function_entry): New function declaration.
            * config/rs6000/rs6000-logue.cc (rs6000_output_function_prologue):
            Support patchable-function-entry by emitting nops before and after
            local entry for the function that needs global entry.
            * config/rs6000/rs6000.cc (rs6000_print_patchable_function_entry):
Skip
            the function that needs global entry till global entry has been
            emitted.
            * config/rs6000/rs6000.h (struct machine_function): New bool member
            global_entry_emitted.

    gcc/testsuite/ChangeLog:

            * gcc.target/powerpc/pr99888-1.c: New test.
            * gcc.target/powerpc/pr99888-2.c: New test.
            * gcc.target/powerpc/pr99888-3.c: New test.
            * gcc.target/powerpc/pr99888-4.c: New test.
            * gcc.target/powerpc/pr99888-5.c: New test.
            * gcc.target/powerpc/pr99888-6.c: New test.
            * c-c++-common/patchable_function_entry-default.c: Adjust for
            powerpc_elfv2 to avoid compilation error.