libgomp.texi: Update "Enabling OpenMP" + OpenACC / invoke.texi: -fopenacc/-fopenmp update
The OpenACC specification does not mention the '!$ ' sentinel for conditional
compilation and the feature was removed in r11-5572-g1d6f6ac693a860
for PR fortran/98011.
libgomp/
* libgomp.texi (Enabling OpenMP): Update for C/C++ attributes;
improve wording especially for Fortran; mention -fopenmp-simd.
(Enabling OpenACC): Minor cleanup; remove conditional compilation
sentinel.
gcc/
* doc/invoke.texi (-fopenacc, -fopenmp, -fopenmp-simd): Use @samp not
@code; document more completely the supported Fortran sentinels.
gcc/fortran
* scanner.cc (skip_free_comments, skip_fixed_comments): Remove
leftover 'OpenACC' from comments about OpenMP's conditional
compilation sentinel.
@@ -2748,9 +2748,10 @@ Typical command lines are
@opindex fopenacc
@cindex OpenACC accelerator programming
@item -fopenacc
-Enable handling of OpenACC directives @code{#pragma acc} in C/C++ and
-@code{!$acc} in Fortran. When @option{-fopenacc} is specified, the
-compiler generates accelerated code according to the OpenACC Application
+Enable handling of OpenACC directives @samp{#pragma acc} in C/C++ and
+@samp{!$acc} in free-form Fortran and @samp{!$acc}, @samp{c$acc} and
+@samp{*$acc} in fixed-form Fortran. When @option{-fopenacc} is specified,
+the compiler generates accelerated code according to the OpenACC Application
Programming Interface v2.6 @w{@uref{https://www.openacc.org}}. This option
implies @option{-pthread}, and thus is only supported on targets that
have support for @option{-pthread}.
@@ -2766,10 +2767,12 @@ can be omitted, to use a target-specific default value.
@opindex fopenmp
@cindex OpenMP parallel
@item -fopenmp
-Enable handling of OpenMP directives @code{#pragma omp} in C/C++,
-@code{[[omp::directive(...)]]}, @code{[[omp::sequence(...)]]} and
-@code{[[omp::decl(...)]]} in C++ and @code{!$omp} in Fortran.
-When @option{-fopenmp} is specified, the
+Enable handling of OpenMP directives @samp{#pragma omp} in C/C++,
+@samp{[[omp::directive(...)]]}, @samp{[[omp::sequence(...)]]} and
+@samp{[[omp::decl(...)]]} in C++ and @samp{!$omp} in Fortran. It
+additionally enables the conditional compilation sentinel @samp{!$} in
+Fortran. In fixed source form Fortran, the sentinels can also start with
+@samp{c} or @samp{*}. When @option{-fopenmp} is specified, the
compiler generates parallel code according to the OpenMP Application
Program Interface v4.5 @w{@uref{https://www.openmp.org}}. This option
implies @option{-pthread}, and thus is only supported on targets that
@@ -2785,10 +2788,12 @@ Enable handling of OpenMP's @code{simd}, @code{declare simd},
and @code{loop} directive, and of combined or composite directives with
@code{simd} as constituent with @code{#pragma omp} in C/C++,
@code{[[omp::directive(...)]]}, @code{[[omp::sequence(...)]]} and
-@code{[[omp::decl(...)]]} in C++ and @code{!$omp} in Fortran.
-Other OpenMP directives are ignored. Unless @option{-fopenmp} is
-additionally specified, the @code{loop} region binds to the current
-task region, independent of the specified @code{bind} clause.
+@code{[[omp::decl(...)]]} in C++ and @code{!$omp} in Fortran. It
+additionally enables the conditional compilation sentinel @samp{!$} in
+Fortran. In fixed source form Fortran, the sentinels can also start with
+@samp{c} or @samp{*}. Other OpenMP directives are ignored. Unless
+@option{-fopenmp} is additionally specified, the @code{loop} region binds
+to the current task region, independent of the specified @code{bind} clause.
@opindex fopenmp-target-simd-clone
@cindex OpenMP target SIMD clone
@@ -877,7 +877,7 @@ skip_free_comments (void)
/* If -fopenmp/-fopenacc, we need to handle here 2 things:
1) don't treat !$omp/!$acc as comments, but directives
- 2) handle OpenMP/OpenACC conditional compilation, where
+ 2) handle OpenMP conditional compilation, where
!$ should be treated as 2 spaces (for initial lines
only if followed by space). */
if (at_bol)
@@ -1106,7 +1106,7 @@ skip_fixed_comments (void)
/* If -fopenmp/-fopenacc, we need to handle here 2 things:
1) don't treat !$omp/!$acc|c$omp/c$acc|*$omp / *$acc as comments,
but directives
- 2) handle OpenMP/OpenACC conditional compilation, where
+ 2) handle OpenMP conditional compilation, where
!$|c$|*$ should be treated as 2 spaces if the characters
in columns 3 to 6 are valid fixed form label columns
characters. */
@@ -136,15 +136,22 @@ changed to GNU Offloading and Multi Processing Runtime Library.
@node Enabling OpenMP
@chapter Enabling OpenMP
-To activate the OpenMP extensions for C/C++ and Fortran, the compile-time
-flag @command{-fopenmp} must be specified. This enables the OpenMP directive
-@code{#pragma omp} in C/C++ and @code{!$omp} directives in free form,
-@code{c$omp}, @code{*$omp} and @code{!$omp} directives in fixed form,
-@code{!$} conditional compilation sentinels in free form and @code{c$},
-@code{*$} and @code{!$} sentinels in fixed form, for Fortran. The flag also
-arranges for automatic linking of the OpenMP runtime library
+To activate the OpenMP extensions for C/C++ and Fortran, the compile-time
+flag @option{-fopenmp} must be specified. For C and C++, this enables
+the handling of the OpenMP directives using @code{#pragma omp} and, for C++, the
+@code{[[omp::directive(...)]]}, @code{[[omp::sequence(...)]]} and
+@code{[[omp::decl(...)]]} attributes. For Fortran, it enables for
+free source form the @code{!$omp} sentinel for directives and the
+@code{!$} conditional compilation sentinel and for fixed source form the
+@code{c$omp}, @code{*$omp} and @code{!$omp} sentinels for directives and
+the @code{c$}, @code{*$} and @code{!$} conditional compilation sentinels.
+The flag also arranges for automatic linking of the OpenMP runtime library
(@ref{Runtime Library Routines}).
+The @option{-fopenmp-simd} flag can be used to enable a subset of
+OpenMP directives that do not require the linking of either the
+OpenMP runtime library or the POSIX threads library.
+
A complete description of all OpenMP directives may be found in the
@uref{https://www.openmp.org, OpenMP Application Program Interface} manuals.
See also @ref{OpenMP Implementation Status}.
@@ -3697,12 +3704,10 @@ pools available and their worker threads run at priority four.
To activate the OpenACC extensions for C/C++ and Fortran, the compile-time
flag @option{-fopenacc} must be specified. This enables the OpenACC directive
-@code{#pragma acc} in C/C++ and @code{!$acc} directives in free form,
-@code{c$acc}, @code{*$acc} and @code{!$acc} directives in fixed form,
-@code{!$} conditional compilation sentinels in free form and @code{c$},
-@code{*$} and @code{!$} sentinels in fixed form, for Fortran. The flag also
-arranges for automatic linking of the OpenACC runtime library
-(@ref{OpenACC Runtime Library Routines}).
+@samp{#pragma acc} in C/C++ and, in Fortran, the @samp{!$acc} sentinel in free
+source form and the @samp{c$acc}, @samp{*$acc} and @samp{!$acc} sentinels in
+fixed source form. The flag also arranges for automatic linking of the OpenACC
+runtime library (@ref{OpenACC Runtime Library Routines}).
See @uref{https://gcc.gnu.org/wiki/OpenACC} for more information.
Hi Sandra and Jakub, I have now updated the patch; on the way, I found an issue in -fopenacc ('!$' is not OpenACC and no longer supported) and the same @code/@samp. I also updated invoke.texi for the same @code/@samp - and added both '!$' and mentioned the 'c$'/'*$' Fortran fixed-form variant. I think the most important bit is that '!$' is also supported by -fopenmp-simd as that's not covered by the OpenMP specification. Otherwise: On 14.10.23 23:46, Sandra Loosemore wrote: > On 10/14/23 13:43, Tobias Burnus wrote: >> The attached patch tries to improve this. Note that it talks about C and >> C++ attributes, even though C23's [[omp::]] support has not yet landed. >> (But is expected very soon.) > > Is somebody actively working on implementing that, and expecting to > get it in before Stage 1 closes? I don't think we should document > features that don't exist yet. Yes. But I have now sneaked in an 'in C++' which can also be easily removed once Jakub's patch is committed or as part of Jakub's patch. > This syntax for C also isn't even in the draft OpenMP 6.0 document so > at this point Well, it is in the git version, which will be released as TR12 in about a month (in time for SC23). It is very unlikely to get removed before OpenMP 6.0 as it is an obvious extension to C++11's attribute support, now that C supports attributes as well. > Other than that... > Use @option markup on options, not @command. Fixed. Was preexisting and I copied it once. I've now checked, the only other use in libgomp.texi was for an actual command (nvprof). > And I think all those @code markups should be @samp instead, or you > could just replace this whole blurb with something like "This flag > enables recognition of the directive syntax documented in the OpenMP > specification, and also arranges for automatic linking..." I think it is more user friendly to document the sentinels. However, I concur that @samp is better. > +OpenMP directives, which do not require the linking of neither the > > s/, which/ that/ I have now used it, but I think it sound odd: "enables *a* subset of OpenMP directives *that* do not require the linking" I concur that with "*the* subset ... *that*" makes sense but I want to avoid stating that *all* directives that do not require linking of libgomp/libpthread are supported. invoke.texi lists all supported directives, but I am not really fond of repeating that list. > s/neither/either/ The fun of whether double negation cancels or enforces the negation or .. ("not .. neither / nor"). Cf. https://en.wikipedia.org/wiki/Double_negative In German and English, both cancellation and enforcement seem to be possible, the latter especially with dialects - while the standard language tends to avoid double negation. Updated patch attached. Thanks, Tobias ----------------- Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, 80634 München; Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas Heurung, Frank Thürauf; Sitz der Gesellschaft: München; Registergericht München, HRB 106955