[Bug lto/56168] [4.8 Regression] GCC seems to disregard -fno-builtin when compiling with LTO

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56168

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2013-02-01
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
   Target Milestone|---                         |4.8.0
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> 2013-02-01 09:42:36 UTC ---
-f[no-]builtin-* is a frontend option not supported by LTO (nor by Fortran
for example).  That it controls also middle-end behavior with respect to
LTO streaming 'pow' as a builtin is a bug I suppose (to be analyzed).
Probably caused by

      /* For variables prefer the builtin if one is available.  */
      else if (TREE_CODE (prevailing->symbol.decl) == FUNCTION_DECL)
        {
          for (e = first; e; e = e->symbol.next_sharing_asm_name)
            if (TREE_CODE (e->symbol.decl) == FUNCTION_DECL
                && DECL_BUILT_IN (e->symbol.decl))
              {
                prevailing = e;
                break;
              }
        }

and LTO un-conditionally initializing all builtins (well, and that's needed
unless we can do that lazily during streaming as we stream builtin decls
by their DECL_FUNCTION_CODE ...).

Hm.  I'll have a looksee.