That is, put D126323 in the status doc and explain its relationship to
OpenACC support.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D126547
This patch adds more documentation for the OpenMP offloading driver.
This includes a new file that describes the overall pipeline becuase
that was not previously explained in full elsewhere.
Reviewed By: ABataev
Differential Revision: https://reviews.llvm.org/D118815
Eachempati.
This patch adds clang (parsing, sema, serialization, codegen) support for the 'depend' clause on the 'taskwait' directive.
Reviewed By: ABataev
Differential Revision: https://reviews.llvm.org/D113540
This patch implements Clang support for an original OpenMP extension
we have developed to support OpenACC: the `ompx_hold` map type
modifier. The next patch in this series, D106510, implements OpenMP
runtime support.
Consider the following example:
```
#pragma omp target data map(ompx_hold, tofrom: x) // holds onto mapping of x
{
foo(); // might have map(delete: x)
#pragma omp target map(present, alloc: x) // x is guaranteed to be present
printf("%d\n", x);
}
```
The `ompx_hold` map type modifier above specifies that the `target
data` directive holds onto the mapping for `x` throughout the
associated region regardless of any `target exit data` directives
executed during the call to `foo`. Thus, the presence assertion for
`x` at the enclosed `target` construct cannot fail. (As usual, the
standard OpenMP reference count for `x` must also reach zero before
the data is unmapped.)
Justification for inclusion in Clang and LLVM's OpenMP runtime:
* The `ompx_hold` modifier supports OpenACC functionality (structured
reference count) that cannot be achieved in standard OpenMP, as of
5.1.
* The runtime implementation for `ompx_hold` (next patch) will thus be
used by Flang's OpenACC support.
* The Clang implementation for `ompx_hold` (this patch) as well as the
runtime implementation are required for the Clang OpenACC support
being developed as part of the ECP Clacc project, which translates
OpenACC to OpenMP at the directive AST level. These patches are the
first step in upstreaming OpenACC functionality from Clacc.
* The Clang implementation for `ompx_hold` is also used by the tests
in the runtime implementation. That syntactic support makes the
tests more readable than low-level runtime calls can. Moreover,
upstream Flang and Clang do not yet support OpenACC syntax
sufficiently for writing the tests.
* More generally, the Clang implementation enables a clean separation
of concerns between OpenACC and OpenMP development in LLVM. That
is, LLVM's OpenMP developers can discuss, modify, and debug LLVM's
extended OpenMP implementation and test suite without directly
considering OpenACC's language and execution model, which can be
handled by LLVM's OpenACC developers.
* OpenMP users might find the `ompx_hold` modifier useful, as in the
above example.
See new documentation introduced by this patch in `openmp/docs` for
more detail on the functionality of this extension and its
relationship with OpenACC. For example, it explains how the runtime
must support two reference counts, as specified by OpenACC.
Clang recognizes `ompx_hold` unless `-fno-openmp-extensions`, a new
command-line option introduced by this patch, is specified.
Reviewed By: ABataev, jdoerfert, protze.joachim, grokos
Differential Revision: https://reviews.llvm.org/D106509
OpenMP 5.1 added support for writing OpenMP directives using [[]]
syntax in addition to using #pragma and this introduces support for the
new syntax.
In OpenMP, the attributes take one of two forms:
[[omp::directive(...)]] or [[omp::sequence(...)]]. A directive
attribute contains an OpenMP directive clause that is identical to the
analogous #pragma syntax. A sequence attribute can contain either
sequence or directive arguments and is used to ensure that the
attributes are processed sequentially for situations where the order of
the attributes matter (remember:
https://eel.is/c++draft/dcl.attr.grammar#4.sentence-4).
The approach taken here is somewhat novel and deserves mention. We
could refactor much of the OpenMP parsing logic to work for either
pragma annotation tokens or for attribute clauses. It would be a fair
amount of effort to share the logic for both, but it's certainly
doable. However, the semantic attribute system is not designed to
handle the arbitrarily complex arguments that OpenMP directives
contain. Adding support to thread the novel parsed information until we
can produce a semantic attribute would be considerably more effort.
What's more, existing OpenMP constructs are not (often) represented as
semantic attributes. So doing this through Attr.td would be a massive
undertaking that would likely only benefit OpenMP and comes with
additional risks. Rather than walk down that path, I am taking
advantage of the fact that the syntax of the directives within the
directive clause is identical to that of the #pragma form. Once the
parser recognizes that we're processing an OpenMP attribute, it caches
all of the directive argument tokens and then replays them as though
the user wrote a pragma. This reuses the same OpenMP parsing and
semantic logic directly, but does come with a risk if the OpenMP
committee decides to purposefully diverge their pragma and attribute
syntaxes. So, despite this being a novel approach that does token
replay, I think it's actually a better approach than trying to do this
through the declarative syntax in Attr.td.
I'm working on the implementation of OpenMP 5.1 feature `atomic compare`.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D100507
Adding features in OpenMP 5.1 specification, as documented in feature change history, to the 5.1 table. I alphabetized the rows of the table according to the category. For deprecating master construct, I just used 'other' as the category.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D90802
There are a few places with unexpected indents that trip over sphinx and
other syntax errors.
Also, the C++ syntax highlighting does not work for
class [[gsl::Owner(int)]] IntOwner {
Use a regular code:: block instead.
There are a few other warnings errors remaining, of the form
'Duplicate explicit target name: "cmdoption-clang--prefix"'. They seem
to be caused by the following
.. option:: -B<dir>, --prefix <arg>, --prefix=<arg>
I am no Restructured Text expert, but it seems like sphinx 1.8.5
tries to generate the same target for the --prefix <arg> and
--prefix=<arg>. This pops up in a lot of places and I am not sure how to
best resolve it
Reviewers: jfb, Bigcheese, dexonsmith, rjmccall
Reviewed By: rjmccall
Differential Revision: https://reviews.llvm.org/D76534
Shilei Tian