Re: gc sections and .eh_frame

[Eric Botcazou <ebotcazou@adacore.com>]

> > Thanks for confirming.  However I think I've grasped Alan's remark and we
> > indeed risk marking all the functions in a given input file if it happens
> > to contain no EH tables because its functions don't need them.
>
> Can that really happen in practice? Doesn't that mean having a .eh_frame
> input section present and (on non-powerpc targets) no .gcc_except_frame?

Yes, that can happen if no functions in the file use EH constructs, which is 
not uncommon I think.  For example in Ada:

with U;
procedure Ma is
i : Integer := 10;
begin
   U.Used (i);
end Ma;


        .file   "ma.adb"
        .section        .rodata
.LC0:
        .string "ma.adb"
        .zero   1
        .section        .text._ada_ma,"ax",@progbits
.globl _ada_ma
        .type   _ada_ma, @function
_ada_ma:
.LFB2:
        pushl   %ebp
.LCFI0:
        movl    %esp, %ebp
.LCFI1:
        subl    $8, %esp
.LCFI2:
        movl    $10, -4(%ebp)
        subl    $12, %esp
        cmpl    $0, -4(%ebp)
        js      .L4
        cmpl    $10, -4(%ebp)
        jg      .L4
        jmp     .L2
.L4:
        subl    $12, %esp
        pushl   $5
        pushl   $.LC0
.LCFI3:
        call    __gnat_rcheck_11
.L2:
        movl    -4(%ebp), %eax
        pushl   %eax
.LCFI4:
        call    u__used
        addl    $16, %esp
        movl    %eax, -4(%ebp)
        leave
        ret
.LFE2:
        .size   _ada_ma, .-_ada_ma
        .section        .eh_frame,"a",@progbits
.Lframe1:
        .long   .LECIE1-.LSCIE1
.LSCIE1:
        .long   0x0
        .byte   0x1
        .string "zP"
        .uleb128 0x1
        .sleb128 -4
        .byte   0x8
        .uleb128 0x5
        .byte   0x0
        .long   __gnat_eh_personality
        .byte   0xc
        .uleb128 0x4
        .uleb128 0x4
        .byte   0x88
        .uleb128 0x1
        .align 4
.LECIE1:
.LSFDE1:
        .long   .LEFDE1-.LASFDE1
.LASFDE1:
        .long   .LASFDE1-.Lframe1
        .long   .LFB2
        .long   .LFE2-.LFB2
        .uleb128 0x0
        .byte   0x4
        .long   .LCFI0-.LFB2
        .byte   0xe
        .uleb128 0x8
        .byte   0x85
        .uleb128 0x2
        .byte   0x4
        .long   .LCFI1-.LCFI0
        .byte   0xd
        .uleb128 0x5
        .byte   0x4
        .long   .LCFI3-.LCFI1
        .byte   0x2e
        .uleb128 0x14
        .byte   0x4
        .long   .LCFI4-.LCFI3
        .byte   0x2e
        .uleb128 0x10
        .align 4
.LEFDE1:
        .section        .note.GNU-stack,"",@progbits
        .ident  "GCC: (GNU) 3.4.5 20050607 (prerelease)"

-- 
Eric Botcazou