OpenMP on gcc

OpenMP on gcc

[Dima Sorkin]

Hi.
 I have some c++ code that should compile both
under GCCs (starting from gcc 3.1 to 4.0) and other
compiler. I want to insert OpenMP pragmas
into code, to optimize it.

1) Starting from which version does GCC support OpenMP ?
2) Will old versions of GCC just ignore OpenMP pragmas, or these
    will cause errors ?

Thank you.
 Dima.

Re: OpenMP on gcc

[Ferad Zyulkyarov]

As I know, OpenMP is being implemented since version 4.2+ But these
gcc versions does not have official release. Based on my experience, I
compiled few simple OpenMP programs in gcc and I was satisfied.

> 1) Starting from which version does GCC support OpenMP ?

As I know 4.2

> 2) Will old versions of GCC just ignore OpenMP pragmas, or these
>     will cause errors ?

Based on the pragma specification unknown pragmas are ignored. But you
have to deal with the omp_* stuff (i.e. omp_set_lock function)

Regards,
Ferad

-- 
Ferad Zyulkyarov
Barcelona Supercomputing Center

Re: OpenMP on gcc

[Tim Prince]

ferad.zyulkyarov@bsc.es wrote:
> As I know, OpenMP is being implemented since version 4.2+ But these
> gcc versions does not have official release. Based on my experience, I
> compiled few simple OpenMP programs in gcc and I was satisfied.
> 

The one problem I have had is that gfortran rejects EQUIVALENCE in 
threadprivate COMMON blocks, as used extensively in legacy applications. 
  I haven't investigated whether any standards bear on this (admittedly 
  undesirable) practice.

Re: OpenMP on gcc

[Ferad Zyulkyarov]

Hi,

My e-mail address appears on the previous message under this thread. I
would like to ask the admins if it is possible to delete it (because
of the spam).

Thanks in advance,
Ferad

Re: OpenMP on gcc

[Steve Kargl]

On Wed, Mar 28, 2007 at 03:14:20PM -0700, Tim Prince wrote:
> ferad.zyulkyarov@bsc.es wrote:
> >As I know, OpenMP is being implemented since version 4.2+ But these
> >gcc versions does not have official release. Based on my experience, I
> >compiled few simple OpenMP programs in gcc and I was satisfied.
> >
> 
> The one problem I have had is that gfortran rejects EQUIVALENCE in 
> threadprivate COMMON blocks, as used extensively in legacy applications. 
>  I haven't investigated whether any standards bear on this (admittedly 
>  undesirable) practice.


The OpenMP vwrsion 2.5 spec is available on line.

   A variable can only appear in a threadprivate directive in the scope
   in which it is declared. It must not be an element of a common block
   or be declared in an EQUIVALENCE statement.

-- 
Steve