[Bug c++/64266] New: Can GCC produce local mergeable symbols for *.__FUNCTION__ and *.__PRETTY_FUNCTION__ function.

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64266

            Bug ID: 64266
           Summary: Can GCC produce local mergeable symbols for
                    *.__FUNCTION__ and *.__PRETTY_FUNCTION__ function.
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
                CC: jason at gcc dot gnu.org

Created attachment 34250
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34250&action=edit
test case

For the following testcase:

extern "C" {
 extern int printf (char *, ...);
 }

 class a {
  public:
   void sub (int i)
     {
       printf ("__FUNCTION__ = %s\n", __FUNCTION__);
       printf ("__PRETTY_FUNCTION__ = %s\n", __PRETTY_FUNCTION__);
     }

   void sub()
   {
       printf ("__FUNCTION__ = %s\n", __FUNCTION__);
   }
 };

int
main (void)
{
  a ax;
  ax.sub (0);
  ax.sub ();
  return 0;
}

Unlink clang, GCC produces a local symbol residing in .symtab and string values
are not in mergeable section:

$ g++ ~/Programming/testcases/pretty-function.c -o a.o
$ readelf -s a.o --wide |  grep PRE
    15: 0000000000400710    17 OBJECT  LOCAL  DEFAULT   14
_ZZN1a3subEiE19__PRETTY_FUNCTION__

$ readelf -p '.rodata' a.out

String dump of section '.rodata':
  [    10]  __FUNCTION__ = %s

  [    23]  __PRETTY_FUNCTION__ = %s

  [    3d]  sub
  [    50]  void a::sub(int)
  [    61]  sub

and clang produces:

$ clang++ ~/Programming/testcases/pretty-function.c -o a.o
$ readelf -s a.out --wide |  grep PRE
(nothing)

$ readelf -p '.rodata' a.o

String dump of section '.rodata':
  [     4]  __FUNCTION__ = %s

  [    17]  sub
  [    1b]  __PRETTY_FUNCTION__ = %s

  [    35]  void a::sub(int)

I'm wondering if we can also process such kind of optimization.
For Inkscape (compiled with -O2), there are following differences:

section                  portion        size        size    compared 
comparison
.rodata                  15.69 %     2.41 MB     2523277     2291412     90.81
%
.strtab                  13.06 %     2.00 MB     2099988     1933845     92.09
%

Where column 'size' is related to GCC and 'compared' is size generated by
clang.

Thanks,
Martin