Re: RFC: SIMD pragma independent of Cilk Plus / OpenMPv4

2013-09-11 Thread Torvald Riegel 
On Mon, 2013-09-09 at 15:37 +0200, Tobias Burnus wrote:
> Dear all,
> 
> sometimes it can be useful to annotate loops for better vectorization,
> which is rather independent from parallelization.
> 
> For vectorization, GCC has [0]:
> a) Cilk Plus's  #pragma simd  [1]
> b) OpenMP 4.0's #pragma omp simd [2]
> 
> Those require -fcilkplus and -fopenmp, respectively, and activate much
> more. The question is whether it makes sense to provide a means to ask
> the compiler for SIMD vectorization without enabling all the other things
> of Cilk Plus/OpenMP. What's your opinion?
> 
> [If one provides it, the question is whether it is always on or not,
> which syntax/semantics it uses [e.g. just the one of Cilk or OpenMP]
> and what to do with conflicting pragmas which can occur in this case.]

SIMD extensions are discussed in both ISO C and C++ study groups (CPLEX
and SG1, respectively).  The exact form that this will take is still
under discussion (it won't be pragmas, but there's no consensus yet on
whether and how much language constructs are needed), but I would
believe that C/C++ will eventually get SIMD features.  Thus, we should
need it at some time anyway (although the languages might adopt
something language-based for fork/join parallelism too).

Torvald

Re: RFC: SIMD pragma independent of Cilk Plus / OpenMPv4

2013-09-11 Thread Torvald Riegel 
On Mon, 2013-09-09 at 10:18 -0400, Tim Prince wrote:
> Current Intel implementations of safelen will fail to vectorize and give 
> notice if the value is set unnecessarily large.  It's been agreed that 
> increasing the safelen value beyond the optimum level should not turn 
> off vectorization.

Yes, it definitely shouldn't.  safelen() or similar constructs are
supposed to be a programmer assertion about correctness, not a
performance hint.

Torvald

Re: [Suggestion] about h8/300 architecture in gcc and binutils

2013-09-11 Thread Chen Gang 
Hello all:

I have send the related issues to "http://gcc.gnu.org/bugzilla";, please
check if you like, thanks.

currently, I only send 3 bugs: Bug58256, Bug58400, Bug58401, the other
bugs may duplicate with these bugs, so I do not send (if they are also
valuable, I will send too).


Next, I should analyse them (better with another related members), my
analyzing way is:

  compare it with another correct compiler (e.g x86 compiler) by code and by 
debugging.

Wish one of these bugs can be fixed by us within a week (although I am
not quite sure for it: I have no experience for compiler development).


Welcome any members' suggestions or completions :-).

Thanks.

On 09/11/2013 09:02 AM, Chen Gang wrote:
> On 09/11/2013 03:55 AM, Michael Schewe wrote:
>> Hello Maintainers,
>>
>> if you like to drop h8/300 support in linux kernel, thats OK for me.
> 
> OK, thanks.
> 
>> But i like to see it still supported in gcc & binutils, at least i have
>> some projects and know companies using this architecture in embedded
>> applications, bare metal without OS. These products have lifetime in
>> range of 10...20 years and need toolchain support for software-updates.
>>
> 
> OK, thank you for your valuable information.
> 
> And it seems the issues of h8/300 for compiling Linux kernel is still
> valuable to be focused on, just like Jeff Law said. :-)
> 
>> Michael
>>
>> Please note for answers: i am only subscribed to binutils mailing list.
>>
> 
> Excuse me, my English is not quite well, and also I am a newbie in
> binutils and gcc mailing list. I guess your meaning is:
> 
>   When send h8/300 related mails, better always include 
> binut...@sourceware.org (although may it is only for gcc issues) ?
> 
> Is it correct ? (if it is correct, not need reply)
> 
> 
> Thanks.
> 
>> Chen Gang schrieb:
>>> On 09/10/2013 10:19 AM, Jeff Law wrote:
 On 09/09/2013 07:13 PM, Chen Gang wrote:
> Hello Maintainers:
>
> After google search and check the Linux kernel, H8/300 is dead, and for
> gcc-4.9.0 and binutils-2.23.2 still has h8300, do we still need it for
> another OS ?
>
> Welcome any suggestions or completions, thanks.
>
>
> The related information in linux kernel next tree:
>
> commit d02babe847bf96b82b12cc4e4e90028ac3fac73f
> Author: Guenter Roeck
> Date:   Fri Aug 30 06:01:49 2013 -0700
>
> Drop support for Renesas H8/300 (h8300) architecture
>
> H8/300 has been dead for several years, and the kernel for it
> has not compiled for ages. Drop support for it.
>
> Cc: Yoshinori Sato
> Acked-by: Greg Kroah-Hartman
> Signed-off-by: Guenter Roeck
>
>
> The related information in gcc/binutils:
>
> We can build h8300 cross-compiler for Linux kernel, successfully,
> but it has many bugs when building Linux kernel with -Os.
> if we still need h8300 for another OS, is it still valuable to send
> these bugs to Bugzilla (although it is found under Linux)?
 It is still useful to send code generation bugs for the H8/300 series to
 the GCC folks.

>>>
>>> OK, thanks, I will wait for 1-2 days which may get another members'
>>> opinions for discussing.
>>>
>>> If no additional opinions, I will report them to Bugzilla, and I should
>>> try to continue 'work' with related members (although I am a newbie for
>>> compiler and binutils programming).
>>>
 jeff



>>>
>>> Thanks.
> 
> 


-- 
Chen Gang