From: Eric Botcazou <ebotcazou@adacore.com>
To: "Jose E. Marchesi" <jose.marchesi@oracle.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH][SPARC] sparc: switch -fasynchronous-unwind-tables on by default.
Date: Sun, 28 Feb 2016 18:35:00 -0000 [thread overview]
Message-ID: <10333302.PFiANu1Ugm@polaris> (raw)
In-Reply-To: <1456435447-23676-1-git-send-email-jose.marchesi@oracle.com>
> In sparc systems glibc uses libgcc's unwinder to implement the
> backtrace(3) function, defaulting to a simple non-dwarf unwinder if
> libgcc_s doesn't provide a working _Unwind_Backtrace.
>
> However, libgcc's unwinder uses .eh_frame instead of .frame_debug, and
> .eh_frame is fully populated only if applications are built with
> -fexceptions or -fasynchronous-unwind-tables.
>
> This patch changes GCC to assume -fasynchronous-unwind-tables by default
> in sparcv9 and sparc64, like other ports (notably x86) do.
eric@polaris:~/svn/gcc/gcc/common/config> grep -r
x_flag_asynchronous_unwind_tables .
./tilegx/tilegx-common.c: opts->x_flag_asynchronous_unwind_tables = 1;
./tilepro/tilepro-common.c: opts->x_flag_asynchronous_unwind_tables = 1;
./i386/i386-common.c: opts->x_flag_asynchronous_unwind_tables = 2;
./s390/s390-common.c: opts->x_flag_asynchronous_unwind_tables = 1;
In particular, the 2 means that it's overridden by USE_IX86_FRAME_POINTER,
i.e. the frame pointer is always enabled instead (e.g on Solaris).
What's the problem exactly here? Simple non-DWARF unwinders usually work fine
with the SPARC architecture thanks to the calling conventions.
--
Eric Botcazou
next prev parent reply other threads:[~2016-02-28 18:35 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-25 21:16 Jose E. Marchesi
2016-02-28 18:35 ` Eric Botcazou [this message]
2016-02-29 15:42 ` Jose E. Marchesi
2016-03-09 10:03 ` Eric Botcazou
2016-03-15 16:38 ` Jose E. Marchesi
2016-03-17 21:17 ` Richard Henderson
2016-03-18 1:07 ` Jose E. Marchesi
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