Re: Ada in gcc-3.4.3 on x86_64

["Dean Kolosiek" <kolosiekweb04 at qwest dot net>]

I followed the build instructions at http://gcc.gnu.org/install/build.html 
which does not mention make -C gcc gnatlib_and_tools


That worked, and I reproduced a problem I saw in 3.3.3. When calling 
a C function from Ada there is no code generated to set %al to the number 
of xmm registers being passed. Variadic C functions use %al to compute a 
jump into a table of movaps instructions to save the xmm registers. The 
result is a jump to a random location.

The Ada I see it in is from the GtkAda package, gtk_generates.adb. The 
declaration is

   function Widget_New
     (T : Glib.GType; Addr : System.Address := System.Null_Address)
      return System.Address;
   pragma Import (C, Widget_New, "gtk_widget_new");

The instructions generated for a call to gtk_widget_new, after a previous 
function call, are:

	call	gtk_window_get_type
	xorl	%esi, %esi
	movq	%rax, %rdi
	call	gtk_widget_new

At this point %al is the lowest byte of %rax, the return value of the
previous function call. (%rax is also being used to set the first parameter
to gtk_widget_new in %rdi.)

This is code generated at the top of a variadic C function which uses %al
to compute a jump:          void variadic (int a, ...)

        pushq   %rbp
.LCFI0:
        movq    %rsp, %rbp
.LCFI1:
        subq    $72, %rsp
.LCFI2:
        movq    %rsi, -168(%rbp)
        movq    %rdx, -160(%rbp)
        movq    %rcx, -152(%rbp)
        movq    %r8, -144(%rbp)
        movq    %r9, -136(%rbp)
        movzbl  %al, %eax
        movq    %rax, -192(%rbp)
        movq    -192(%rbp), %rdx
        leaq    0(,%rdx,4), %rax
        movq    $.L2, -192(%rbp)
        subq    %rax, -192(%rbp)
        leaq    -1(%rbp), %rax
        movq    -192(%rbp), %rdx
        jmp     *%rdx
        movaps  %xmm7, -15(%rax)
        movaps  %xmm6, -31(%rax)
        movaps  %xmm5, -47(%rax)
        movaps  %xmm4, -63(%rax)
        movaps  %xmm3, -79(%rax)
        movaps  %xmm2, -95(%rax)
        movaps  %xmm1, -111(%rax)
        movaps  %xmm0, -127(%rax)
.L2:
        movl    %edi, -180(%rbp)
 


> > Add --enable-languages=c,c++,ada,g77 and make sure that you have an
> > Ada compiler installed since such is needed for bootstrapping,
> 
> More specifically, he should follow the documentation and call
> make -C gcc gnatlib_and_tools  (was needed with GCC 3.4, is no longer
> needed with 4.0).
> 
> Arno