Re: [RFA] Need post-processing of parameters for function calls in Ada

[Daniel Jacobowitz <drow@false.org>]

On Tue, Jan 08, 2008 at 06:36:22AM -0800, Joel Brobecker wrote:
> Because the conversion is so Ada specific (conversion from one form
> of array to another), the conversion needs to be performed by the
> Ada language.  The attached patch adds a call to ada_convert_actuals()
> inside call_function_by_hand when doing the call in Ada.  We need
> to do the conversion there rather than ahead of calling call_function_
> by_hand because some conversions need to allocate some memory in
> the inferior, and we do it in the stack area that this function sets up.

Is this an argument coercion?  The right place may be
value_arg_coerce.  If the only problem is that you need the sp, we
could supply it to that function and move the coercion after the stack
frame setup.  I don't think this will be a problem even if we need a
function call during argument coercion.

This might allow a useful option, to avoid calling malloc when passing
strings to a C function.  We can not do that in general, since the
function might save the pointer, but there are some cases (like strcmp).

Really this sort of thing ought to go through the language vector, but
I'm happy leaving that until a second language needs it.

> 
> 2008-01-08  Joel Brobecker  <brobecker@adacore.com>
> 
>         * infcall.c: #include "ada-lang.h".
>         (call_function_by_hand): Add post processing of function arguments
>         for Ada function calls.
>         * Makefile.in (infcall.o): Update dependencies.
> 
> I was able to write a testcase that reproduces the problem:
> 
> 2008-01-08  Joel Brobecker  <brobecker@adacore.com>
> 
>         * gdb.ada/arrayparam: New test program.
>         * gdb.ada/arrayparam.exp: New testcase.
> 
> Tested on x86-linux, no regression.
> OK to commit?
> 
> Thanks,
> -- 
> Joel

> Index: infcall.c
> ===================================================================
> --- infcall.c	(revision 98)
> +++ infcall.c	(revision 99)
> @@ -34,6 +34,7 @@
>  #include "gdb_string.h"
>  #include "infcall.h"
>  #include "dummy-frame.h"
> +#include "ada-lang.h"
>  
>  /* NOTE: cagney/2003-04-16: What's the future of this code?
>  
> @@ -556,6 +557,9 @@ call_function_by_hand (struct value *fun
>    if (nargs < TYPE_NFIELDS (ftype))
>      error (_("too few arguments in function call"));
>  
> +  if (current_language->la_language == language_ada)
> +    ada_convert_actuals (function, nargs, args, &sp);
> +
>    {
>      int i;
>      for (i = nargs - 1; i >= 0; i--)
> Index: Makefile.in
> ===================================================================
> --- Makefile.in	(revision 98)
> +++ Makefile.in	(revision 99)
> @@ -2271,7 +2271,7 @@ ia64-tdep.o: ia64-tdep.c $(defs_h) $(inf
>  infcall.o: infcall.c $(defs_h) $(breakpoint_h) $(target_h) $(regcache_h) \
>  	$(inferior_h) $(gdb_assert_h) $(block_h) $(gdbcore_h) $(language_h) \
>  	$(objfiles_h) $(gdbcmd_h) $(command_h) $(gdb_string_h) $(infcall_h) \
> -	$(dummy_frame_h)
> +	$(dummy_frame_h) $(ada_lang_h)
>  inf-child.o: inf-child.c $(defs_h) $(regcache_h) $(memattr_h) $(symtab_h) \
>  	$(target_h) $(inferior_h) $(gdb_string_h)
>  infcmd.o: infcmd.c $(defs_h) $(gdb_string_h) $(symtab_h) $(gdbtypes_h) \

> Index: gdb.ada/arrayparam.exp
> ===================================================================
> --- gdb.ada/arrayparam.exp	(revision 0)
> +++ gdb.ada/arrayparam.exp	(revision 100)
> @@ -0,0 +1,61 @@
> +# Copyright 2008 Free Software Foundation, Inc.
> +#
> +# This program is free software; you can redistribute it and/or modify
> +# it under the terms of the GNU General Public License as published by
> +# the Free Software Foundation; either version 3 of the License, or
> +# (at your option) any later version.
> +#
> +# This program is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +if $tracelevel then {
> +    strace $tracelevel
> +}
> +
> +load_lib "ada.exp"
> +
> +set testdir "arrayparam"
> +set testfile "${testdir}/foo"
> +set srcfile ${srcdir}/${subdir}/${testfile}.adb
> +set binfile ${objdir}/${subdir}/${testfile}
> +
> +file mkdir ${objdir}/${subdir}/${testdir}
> +if {[gdb_compile_ada "${srcfile}" "${binfile}" executable [list debug]] != "" } {
> +  return -1
> +}
> +
> +gdb_exit
> +gdb_start
> +gdb_reinitialize_dir $srcdir/$subdir
> +gdb_load ${binfile}
> +
> +set bp_location [gdb_get_line_number "STOP" ${testdir}/foo.adb]
> +runto "foo.adb:$bp_location"
> +
> +# Verify that a call to a function that takes an array as a parameter
> +# works without problem.
> +
> +gdb_test "print call_me (\"bonjour\")" \
> +         "void" \
> +         "print call_me (\"bonjour\")"
> +
> +# Verify that the array was passed properly by checking the global
> +# variables that Call_Me sets as side-effects.
> +
> +gdb_test "print first" \
> +         "98 'b'" \
> +         "print first after function call"
> +
> +gdb_test "print last" \
> +         "114 'r'" \
> +         "print lasta after function call"
> +
> +gdb_test "print length" \
> +         "7" \
> +         "print length after function call"
> +
> Index: gdb.ada/arrayparam/pck.adb
> ===================================================================
> --- gdb.ada/arrayparam/pck.adb	(revision 0)
> +++ gdb.ada/arrayparam/pck.adb	(revision 100)
> @@ -0,0 +1,28 @@
> +--  Copyright 2008 Free Software Foundation, Inc.
> +--
> +--  This program is free software; you can redistribute it and/or modify
> +--  it under the terms of the GNU General Public License as published by
> +--  the Free Software Foundation; either version 3 of the License, or
> +--  (at your option) any later version.
> +--
> +--  This program is distributed in the hope that it will be useful,
> +--  but WITHOUT ANY WARRANTY; without even the implied warranty of
> +--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +--  GNU General Public License for more details.
> +--
> +--  You should have received a copy of the GNU General Public License
> +--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +package body Pck is
> +
> +   procedure Call_Me (Str : String) is
> +   begin
> +      Length := Str'Length;
> +      if Length > 0 then
> +         First := Str (Str'First);
> +         Last := Str (Str'Last);
> +      end if;
> +   end Call_Me;
> +
> +end Pck;
> +
> Index: gdb.ada/arrayparam/pck.ads
> ===================================================================
> --- gdb.ada/arrayparam/pck.ads	(revision 0)
> +++ gdb.ada/arrayparam/pck.ads	(revision 100)
> @@ -0,0 +1,25 @@
> +--  Copyright 2008 Free Software Foundation, Inc.
> +--
> +--  This program is free software; you can redistribute it and/or modify
> +--  it under the terms of the GNU General Public License as published by
> +--  the Free Software Foundation; either version 3 of the License, or
> +--  (at your option) any later version.
> +--
> +--  This program is distributed in the hope that it will be useful,
> +--  but WITHOUT ANY WARRANTY; without even the implied warranty of
> +--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +--  GNU General Public License for more details.
> +--
> +--  You should have received a copy of the GNU General Public License
> +--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +package Pck is
> +
> +   First : Character := ASCII.NUL;
> +   Last : Character := ASCII.NUL;
> +   Length : Integer := 0;
> +
> +   procedure Call_Me (Str : String);
> +
> +end Pck;
> +
> Index: gdb.ada/arrayparam/foo.adb
> ===================================================================
> --- gdb.ada/arrayparam/foo.adb	(revision 0)
> +++ gdb.ada/arrayparam/foo.adb	(revision 100)
> @@ -0,0 +1,26 @@
> +--  Copyright 2008 Free Software Foundation, Inc.
> +--
> +--  This program is free software; you can redistribute it and/or modify
> +--  it under the terms of the GNU General Public License as published by
> +--  the Free Software Foundation; either version 3 of the License, or
> +--  (at your option) any later version.
> +--
> +--  This program is distributed in the hope that it will be useful,
> +--  but WITHOUT ANY WARRANTY; without even the implied warranty of
> +--  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +--  GNU General Public License for more details.
> +--
> +--  You should have received a copy of the GNU General Public License
> +--  along with this program.  If not, see <http://www.gnu.org/licenses/>.
> +
> +with Pck; use Pck;
> +
> +procedure Foo is
> +   My_String : constant String := "Hello World";
> +begin
> +   First := ASCII.NUL;
> +   Last := ASCII.NUL;
> +   Length := -1;
> +   Call_Me (My_String);  -- STOP
> +end Foo;
> +


-- 
Daniel Jacobowitz
CodeSourcery