[Bug ada/10670] gcc ignors 'pragma Machine_Attribute' directive

["gnat-dev at buzco dot nyct dot net" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10670



------- Additional Comments From gnat-dev at buzco dot nyct dot net  2003-11-01 04:53 -------
Subject: Re:  gcc ignors 'pragma Machine_Attribute' directive

: r! uname -a
Linux buzco.nyct.net 2.2.16 #6 Sat Oct 26 10:26:53 EDT 2002 i586 unknown

: r! gcc --version
gcc (GCC) 3.3.2

On 03-10-28 11:57:49, berndtrog at yahoo dot com wrote:

| > Please, where in the LRM is a pragma Machine_Attribute() mentioned.

| It's an implementation defined pragma:
| http://gcc.gnu.org/onlinedocs/gnat_rm/Implementation-Defined-Pragmas.
| html#Implementation%20Defined%20Pragmas

OK, gotcha, should have thought of that before asking.

Except that that documentation +may+ have been correct for GNAT-3.x
based on gcc-2.8.1 but is wrong for GCC-3.x.
: This pragma is semantically equivalent to
: __attribute__((string_expression)) in GNU C, where string_expression
: is recognized by the GNU C macros VALID_MACHINE_TYPE_ATTRIBUTE and
: VALID_MACHINE_DECL_ATTRIBUTE which are defined in the configuration
: header file tm.h for each machine.

But the only place these macros are mentioned in current code are:
: /* Old target macros that have moved to the target hooks structure.  */
:     #pragma GCC poison ASM_OPEN_PAREN ASM_CLOSE_PAREN                      \
:            [ ... ]
:            VALID_MACHINE_DECL_ATTRIBUTE VALID_MACHINE_TYPE_ATTRIBUTE       \
:     [ ... ]

| > Please submit some sample test code that breaks.

| I've already submitted an example at the time when I opened this PR on
| 2003-05-07.

Yeah, new at this "bugzilla" thing and missed it.

| BTW, Geert Bosch wrote a comment on this issue in:
| http://gcc.gnu.org/ml/gcc/2003-05/msg00703.html

Yah, and he had a syntax error that didn't seem to be caught.

=== End quoted text ===

OK, bug verified as of this date w/ following stuff:

--		     TITLE :
    --	          LANGUAGE : Ada
    --		    MODULE : Boot_A
    --	      COMPONENT OF : BuZco Software (Gazelle)
    -- PARENT ORGANIZATION : BuzCo Systems
    --	     LATEST AUTHOR : Buz Cory
    --		   $RCSfile$
    --            $Revision$
    --                $Date$
-- --------------------------------------------------------------------
-- EXTERNAL MODULES USED
-- --------------------------------------------------------------------
-- PURPOSE :
-- --------------------------------------------------------------------
-- OVERVIEW:
-- --------------------------------------------------------------------
-- NOTICES, LICENSE follow; NOTES, HISTORY at end
-- ----------------------------------------
    -- This software is part of the Gazelle suite of useful,
	-- [ snip boilerplate :) ]

    procedure
Boot_A ;

pragma Machine_Attribute
    ( Entity => Boot_A
    , Attribute_Name => "section ("".bootloader"")"
    ) ;

--		     TITLE :
    --	          LANGUAGE : Ada
    --		    MODULE : Boot_A
    --	      COMPONENT OF : BuZco Software (Gazelle)
    -- PARENT ORGANIZATION : BuzCo Systems
    --	     LATEST AUTHOR : Buz Cory
    --		   $RCSfile$
    --            $Revision$
    --                $Date$
-- --------------------------------------------------------------------
-- EXTERNAL MODULES USED
    with Gazelle ;
-- --------------------------------------------------------------------
-- PURPOSE :
-- --------------------------------------------------------------------
-- OVERVIEW:
-- --------------------------------------------------------------------

procedure			Boot_A
is

    body_RCSid			: aliased constant Gazelle .RCS_String :=
	"$Id$"
	;

begin
    null ;
end Boot_A ;

> : /usr/bin/gnatmake [ ... ] -c boot_a.adb
> : gcc -c [ ... ] boot_a.adb
> boot_a.ads:49: warning: `section (".bootloader")' attribute directive ignored

And similarly for :

    pragma Linker_Section
	( Entity => Boot_A_L
	, Section => ".bootloader"
	) ;

> : r! make boot_a_l.o
> /usr/bin/gnatmake [ ... ] -c boot_a_l.adb
> gcc -c [ ... ] boot_a_l.adb
> boot_a_l.adb:52:05: warning: constant "body_RCSid" is not referenced
> boot_a_l.ads:53:18: warning: section attributes are not supported for
> boot_a_l.ads:53:18: warning: this target

But :

> void boot(void) __attribute__ ((section (".bootloader"))) ;

> void boot(void)
> {
>     int		a ;

>     a = a++ ;
>     }

> : r! objdump -h boot_c.o
> Yields :

> boot_c.o:     file format elf32-i386

> Sections:
> Idx Name          Size      VMA       LMA       File off  Algn
>   [ ... ]
>   3 .bootloader   00000013  00000000  00000000  00000034  2**0
>                   CONTENTS, ALLOC, LOAD, READONLY, CODE

and finally, the message for "attribute directive ignored" appears only
one place in the code, in gcc/attribs.c.

My best guess at the moment is that this is a +boundary+ (API) problem.
What the back end expects in 3.x is different from 2.8.x and the front
end failed to change w/ it.

I expect to follow this up more as soon as I get a visual debugger that
knows Ada working w/ the new object format.

It would please to be assigned to this bug.

--
Buz Cory of BuzCo Systems -- New York NY USA http://BuzCo.nyct.net
<gnat-dev@BuzCo.nyct.net> (Buz as GNAT Programmer)
write to <helpdesk@BuzCo.nyct.net> for FREE help with:
    Installing/Configuring Linux
    Getting started with the Ada Programming Language.