On Fri, May 31, 2013 at 11:13 AM, Mike Stump <mikest...@comcast.net> wrote:
> So, on darwin, the new tools don't like FDE information when you have:
>
> __Z24default_no_named_sectionPKcjP9tree_node:
> LFB588:
> LFE588:
>
> in the object file.
>
> $ dwarfdump --eh-frame --verify varasm.o
> ----------------------------------------------------------------------
> File: varasm.o (x86_64)
> ----------------------------------------------------------------------
> Verifying EH Frame... error: FDE row for address 0x00000000000058f0 is not in
> the FDE address range.
>
> 0x000020e0: FDE
> length: 0x0000001c
> CIE_pointer: 0x00000000
> start_addr: 0x00000000000058f0
> __Z24default_no_named_sectionPKcjP9tree_node
> range_size: 0x0000000000000000 (end_addr = 0x00000000000058f0)
> DW_CFA_nop
> DW_CFA_nop
> DW_CFA_nop
> DW_CFA_nop
> DW_CFA_nop
> DW_CFA_nop
> DW_CFA_nop
> Instructions: 0x00000000000058f0: CFA=rsp+8 rip=[rsp]
>
> which, well, seems reasonable. This causes the static linker to reject it.
> Now, one can prune out the pair, but, I think really, we either need to have
> a default of 0 (to crash in a nice way), or an assert (to crash in a nice
> way). Just falling off then end into space (the next function in the
> executable file), seems wrong.
>
> Ok?
>
> PR57438
> * varasm.c (default_no_named_section): Assert instead.
This will only fix the GCC source but not other sources which does:
void f(void)
{
__builtin_unreachable();
}
Thanks,
Andrew
>
> Index: varasm.c
> ===================================================================
> --- varasm.c (revision 199270)
> +++ varasm.c (working copy)
> @@ -6052,7 +6052,7 @@ default_no_named_section (const char *na
> {
> /* Some object formats don't support named sections at all. The
> front-end should already have flagged this as an error. */
> - gcc_unreachable ();
> + gcc_assert (0);
> }
>
> #ifndef TLS_SECTION_ASM_FLAG
>
