[fortran] Different FUNC_DECLS with the same DECL_NAME - MAIN__ and named PROGRAM main functions [was Re: gcc-4.5-20090528 is now available]

[Jerry DeLisle]

Tobias Burnus wrote:
> Dave Korn wrote:
>> Dave Korn wrote:
>>> Dave Korn wrote:
>>>> Tobias Burnus wrote:
>>>>> I agree that for "main" the call to "__main()" should happend and thus
>>>>> expand_main_function should be called. I'm not sure in about the exact
>>>>> assumptions of the middle end. In principle, it would be OK if the
>>>>> MAIN__ function would show up as MAIN__ in gimple/-fdump-tree-original.
>>>>> The only potential inconvenience I see, is the mentioned reference to
>>>>> MAIN__ instead of <program name> in middle-end warnings, which can
>>>>> confuse users.
>>   Is it legitimate to have a space in an IDENTIFIER_NODE?  I have a cheeky idea:
> 
>> -  gfc_get_symbol (name, ns, &main_program);
>> +  identifier = gfc_get_string ("PROGRAM %s", name);
> 
>>   That should give reasonable warnings from the middle end, no?  I don't know
>> what it might do to debugging though.
> 
> Currently one can use "b MAIN__" and "b helloworld" in the debugger:
> 
> (gdb) b helloworld
> Breakpoint 1 at 0x400737: file test.f90, line 3.
> (gdb) b MAIN__
> Note: breakpoint 1 also set at pc 0x400737.
> Breakpoint 2 at 0x400737: file test.f90, line 3.
> (gdb) b main
> Breakpoint 3 at 0x4007b9: file test.f90, line 9.
> 
> I have another idea: Just handle "PROGRAM main" specially by using the
> name "MAIN__". It should be still quite readable in the middle-end
> diagnostics. Furthermore, it matches the assembler name and using "b
> main" one still get something useful - and it is less confusing for
> everyone (middle end, users of -fdump-tree-original etc.) if there is
> only a single "main".
> 
> Tobias
> 
> 
> Index: gcc/fortran/trans-decl.c
> ===================================================================
> --- gcc/fortran/trans-decl.c    (Revision 148004)
> +++ gcc/fortran/trans-decl.c    (Arbeitskopie)
> @@ -289,7 +289,10 @@ gfc_get_label_decl (gfc_st_label * lp)
>  static tree
>  gfc_sym_identifier (gfc_symbol * sym)o commit
>  {
> -  return (get_identifier (sym->name));
> +  if (sym->attr.is_main_program && strcmp (sym->name, "main") == 0)
> +    return (get_identifier ("MAIN__"));
> +  else
> +    return (get_identifier (sym->name));
>  }
> 
> 
> @@ -3874,6 +3877,8 @@ create_main_function (tree fndecl)
>    tmp =  build_function_type_list (integer_type_node, integer_type_node,
>                                    build_pointer_type (pchar_type_node),
>                                    NULL_TREE);
> +  main_identifier_node = get_identifier ("main");
> +  ftn_main = build_decl (FUNCTION_DECL, main_identifier_node, tmp);
>    ftn_main = build_decl (FUNCTION_DECL, get_identifier ("main"), tmp);
>    DECL_EXTERNAL (ftn_main) = 0;
>    TREE_PUBLIC (ftn_main) = 1;
> 
> 
Tobias and Dave,

I tested the above on x86-64 Linux.  OK to commit.

Jerry