Re: [PATCH] Further improved native as support on Solaris/x86

[Jakub Jelinek <jakub at redhat dot com>]

On Fri, Jul 21, 2006 at 05:27:29PM -0600, Roger Sayle wrote:
>         .section        .rodata
>         .align 4
>         .align 4
> .L8:
>         .long   .L3-.L8
>         .long   .L4-.L8
>         .long   .L5-.L8
>         .long   .L4-.L8
>         .long   .L6-.L8
>         .long   .L7-.L8
>         .text
> .L4:
>         movl    $1, %eax
> ...
> 
> Notice that the symbol .L8 is in the section .rodata, and the symbol
> .L4 (and all the others) are in the section .L4.
> 
> The outcome is the Solaris assembler issues the fatal error:
> 
> sunfire% as -xarch=generic64 switch.s
> Assembler: switch.c
>         "switch.s", line 68 : Warning: Illegal subtraction - symbols from different sections: ".LFB2", ".DOT-1"
>         "switch.s", line 20 : Illegal subtraction - symbols from different sections: ".L3", ".L8"
> 
> 
> As you point out above, this is the subtraction of two symbols in
> different sections, neither of with if "." or ".+CONST".

Yes, it is the third case, local label in the same fragment, that
gas handles just fine and Solaris as is clearly less capable of
dealing with it.
         .section        .rodata
         .align 4
.L8:
         .long   .L3-.
         .long   (.L4+4)-.
         .long   (.L5+8)-.
         .long   (.L4+12)-.
         .long   (.L6+16)-.
         .long   (.L7+20)-.
would work with Solaris as, then we can certainly teach GCC to emit
it there that way, but GCC would need to know if . here means the start
or end of the .long.

	Jakub