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Re: [google] Add function name to function_patch_* sections (issue9025045)


ok.

David

On Tue, Apr 30, 2013 at 1:34 PM, Harshit Chopra <harshit@google.com> wrote:
> Adding function name to the function_patch_* sections when -ffunction-sections is provided. Helps in garbage collecting dead functions with the help of linker.
>
> Tested:
>   Tested using 'make -k check-gcc RUNTESTFLAGS="i386.exp=patch* --target_board=unix\{-m32,,-m64\}"'.
>
> 2013-04-30  Harshit Chopra  <harshit@google.com>
>
>         * gcc/config/i386/i386.c (ix86_output_function_nops_prologue_epilogue):
>         (ix86_elf_asm_named_section):
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index aa6ec82..7cb832b 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -11285,6 +11285,8 @@ ix86_output_function_nops_prologue_epilogue (FILE *file,
>    unsigned int section_flags = SECTION_RELRO;
>    char *section_name_comdat = NULL;
>    const char *decl_section_name = NULL;
> +  const char *func_name = NULL;
> +  char *section_name_function_sections = NULL;
>    size_t len;
>
>    gcc_assert (num_remaining_nops >= 0);
> @@ -11336,12 +11338,24 @@ ix86_output_function_nops_prologue_epilogue (FILE *file,
>      {
>        decl_section_name =
>            TREE_STRING_POINTER (DECL_SECTION_NAME (current_function_decl));
> -      len = strlen (decl_section_name) + strlen (section_name) + 1;
> +      len = strlen (decl_section_name) + strlen (section_name) + 2;
>        section_name_comdat = (char *) alloca (len);
>        sprintf (section_name_comdat, "%s.%s", section_name, decl_section_name);
>        section_name = section_name_comdat;
>        section_flags |= SECTION_LINKONCE;
>      }
> +  else if (flag_function_sections)
> +    {
> +      func_name = XSTR (XEXP (DECL_RTL (current_function_decl), 0), 0);
> +      if (func_name)
> +        {
> +          len = strlen (func_name) + strlen (section_name) + 2;
> +          section_name_function_sections = (char *) alloca (len);
> +          sprintf (section_name_function_sections, "%s.%s", section_name,
> +                   func_name);
> +          section_name = section_name_function_sections;
> +        }
> +    }
>    section = get_section (section_name, section_flags, current_function_decl);
>    switch_to_section (section);
>    /* Align the section to 8-byte boundary.  */
> @@ -11369,7 +11383,7 @@ ix86_elf_asm_named_section (const char *name, unsigned int flags,
>                              tree decl)
>  {
>    const char *section_name = name;
> -  if (HAVE_COMDAT_GROUP && flags & SECTION_LINKONCE)
> +  if (!flag_function_sections && HAVE_COMDAT_GROUP && flags & SECTION_LINKONCE)
>      {
>        const int prologue_section_name_length =
>            sizeof(FUNCTION_PATCH_PROLOGUE_SECTION) - 1;
>
> --
> This patch is available for review at http://codereview.appspot.com/9025045


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