Re: [PATCH] Compile tst-cleanupx4 test with -fexceptions

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Jun 30, 2016 at 3:42 AM, Aurelien Jarno <aurelien@aurel32.net> wrote:
> On 2016-06-01 14:17, H.J. Lu wrote:
>> tst-cleanupx4 is linked with tst-cleanupx4.o and tst-cleanup4aux.o.
>> Since tst-cleanupx4.o is compiled from tst-cleanup4.c with -fexceptions,
>> tst-cleanupx4.c should also be compiled with -fexceptions.
>>
>> Tested on x86-64 and i686.  OK for master?
>>
>>
>> H.J.
>> --
>>       [BZ 18645]
>>       * nptl/Makefile (extra-test-objs): Add tst-cleanupx4aux.o
>>       (test-extras): Add tst-cleanupx4aux.
>>       (CFLAGS-tst-cleanupx4aux.c): New.  Set to -fexceptions.
>>       ($(objpfx)tst-cleanupx4): Replace tst-cleanup4aux.o with
>>       tst-cleanupx4aux.o.
>>       * nptl/tst-cleanupx4aux.c: New file.
>> ---
>>  nptl/Makefile           | 8 +++++---
>>  nptl/tst-cleanupx4aux.c | 1 +
>>  2 files changed, 6 insertions(+), 3 deletions(-)
>>  create mode 100644 nptl/tst-cleanupx4aux.c
>
> I am probably a bit late, but I have been pointed in the past there that
> the point of tst-cleanupx4 is actually to test unwinding through a
> function not compliled with -fexceptions:
>
> https://sourceware.org/ml/libc-alpha/2014-07/msg00299.html
>
> Note that I have identified the GCC change which introduced this
> regression:
>
> http://www.sourceware.org/ml/libc-alpha/2015-11/msg00533.html
>

I can understand it won't be considered as a GCC bug:

'-fexceptions'
     Enable exception handling.  Generates extra code needed to
     propagate exceptions.  For some targets, this implies GCC generates
     frame unwind information for all functions, which can produce
     significant data size overhead, although it does not affect
     execution.  If you do not specify this option, GCC enables it by
     default for languages like C++ that normally require exception
     handling, and disables it for languages like C that do not normally
     require it.  However, you may need to enable this option when
     compiling C code that needs to interoperate properly with exception
     handlers written in C++.  You may also wish to disable this option
     if you are compiling older C++ programs that don't use exception
     handling.

Can we make tst-cleanupx4 to pass on i686 without -fexceptions
using the current GCC?

-- 
H.J.