[00/12] OpenMP: Metadirective support + "declare variant" improvements

This series of patches is a revised and extended version of the metadirective
patches I previously posted in January:

https://gcc.gnu.org/pipermail/gcc-patches/2024-January/642005.html

Those in turn were based on work by Kwok originally implemented on the
devel/omp/gcc-11 branch in 2021 and previously submitted for mainline 3+
years ago.

The current set comprises 12 parts.  Parts 1-7 are fairly close to the
January patch set, but incorporating a number of bug fixes and
revisions for the review comments from Tobias.  Part 3, in particular,
has a lot of changes to address both a buggy interface between the
compiler and libgomp, and Tobias's comments about bit-rotten target
support.

Parts 8-11 are new.  Part 9 is a big patch that merges the dynamic selector
support to "declare variant", revises internal interfaces, and also fixes
PR114596 and other bugs relating to matching and scoring.  The other pieces
are more self-contained fixes and improvements.

Part 12 is an updated patch for the implementation status table in the
libgomp manual.

As a general overview of what has changed here relative to the January patch
set:

* The dynamic selector support added for metadirective has been
  integrated with declare variant; both directives now use common data
  structures and scoring/sorting code.  In particular, for calls to
  "declare variant" functions that cannot be resolved during
  gimplification, it now creates the same gimple structure used by
  metadirective instead of using a magic placeholder symbol, and all
  the support code used to track and process the placeholders has been
  removed.

* Along the way, I found/fixed a serious bug in the resolution code in
  the previously-posted metadirective patches; it was not saving
  information about the OpenMP context needed to match/score construct
  selectors during gimplification for use in late resolution, and
  instead incorrectly calling the function dependent on being invoked
  during gimplification during late resolution.  It was also failing
  to account for "declare simd"'s effect on scoring.

* I also found/fixed a serious bug in the existing mainline "declare
  variant" scoring code that also affected the previous version of the
  metadirective patches (PR 114596).

* Overall I tried to improve the software engineering aspect of the
  scoring and matching code, making it better-documented and easier to
  follow and correlate to the OpenMP specification.

* In the Fortran front end, I moved the filtering-out of metadirective
  variants that can't possibly match from the parsing phase to the
  translation phase, following Tobias's recommendation.

* I've updated the logic for when "declare target" adds a target
  construct selector to the OpenMP context to follow recent versions
  of the spec (the implementation now on mainline was for the language
  in the 5.0 spec).

* For both metadirective and declare variant, when the gimplifier
  processes metadirectives/calls that can't be resolved at that time,
  it now filters out the variants that can't possibly match instead of
  preserving all of them for late resolution, which might produce
  better optimization opportunities.  (The front ends already do this
  once at parse time, but additional info is available during
  gimplification that may allow additional variants to be discarded.)

* I fixed some bit-rot in the libgomp support for the target_device
  selector, and adjusted the interface between the compiler and libgomp
  to correctly handle selectors with multiple properties (previously it
  was only handling the first one).

* I also added a diagnostic for requirement from the spec that
  kind(any) cannot be used with any other properties.  It turns out
  there were multiple testcases that incorrectly did this.

In terms of what remains to be done:

* There is one test regression in libgomp, declare-variant-1.f90 hangs
  during execution at -O0 only.  I looked at this briefly but didn't make
  any progress on debugging it.

* I haven't solved the issues discussed in issue PR113904 about the
  scoping of expressions in "declare variant" dynamic selectors.  For
  C and C++, I have a good idea of how to implement the provisions in
  the spec that allow references to argument variables of the variant
  function.  For now it diagnoses this with a "sorry"; meanwhile it
  *does* parse the argument variables in the correct scope, and
  correctly handles other symbols in scope, including class members
  and "this" in C++.  For Fortran, I'm unsure of the semantics, and
  for "declare variant" it currently rejects non-constant expressions
  in dynamic selectors.

I think both of those issues could be addressed with follow-up
patches.  This is already a large and complicated patch set, and I
hope that by submitting it for review early in stage 1 it will be
possible to get at least some parts of it committed in a timely manner
and reduce the burden of maintaining these patches out of tree.

-Sandra

Sandra Loosemore (12):
  OpenMP: metadirective tree data structures and front-end interfaces
  OpenMP: middle-end support for metadirectives
  libgomp: runtime support for target_device selector
  OpenMP: C front end support for metadirectives
  OpenMP: C++ front-end support for metadirectives
  OpenMP: common c/c++ testcases for metadirectives
  OpenMP: Fortran front-end support for metadirectives.
  OpenMP: Reject other properties with kind(any)
  OpenMP: Extend dynamic selector support to declare variant
  OpenMP: Remove dead code from declare variant reimplementation
  OpenMP: Update "declare target"/OpenMP context interaction
  OpenMP: Update documentation of metadirective implementation status.

 gcc/Makefile.in                               |    2 +-
 gcc/builtin-types.def                         |    2 +
 gcc/c-family/c-attribs.cc                     |    2 -
 gcc/c-family/c-common.h                       |    4 +-
 gcc/c-family/c-gimplify.cc                    |   27 +
 gcc/c-family/c-omp.cc                         |   60 +-
 gcc/c-family/c-pragma.cc                      |    1 +
 gcc/c-family/c-pragma.h                       |    1 +
 gcc/c/c-decl.cc                               |    8 +-
 gcc/c/c-parser.cc                             |  473 +++-
 gcc/cgraph.cc                                 |    2 -
 gcc/cgraph.h                                  |   12 +-
 gcc/cgraphclones.cc                           |    2 +-
 gcc/cp/cp-tree.h                              |    2 +
 gcc/cp/decl.cc                                |    2 +-
 gcc/cp/decl2.cc                               |    9 +-
 gcc/cp/parser.cc                              |  526 ++++-
 gcc/cp/parser.h                               |    7 +
 gcc/cp/pt.cc                                  |  120 +
 gcc/cp/semantics.cc                           |    3 +-
 gcc/doc/generic.texi                          |   32 +
 gcc/doc/gimple.texi                           |    6 +
 gcc/fortran/decl.cc                           |   29 +
 gcc/fortran/dump-parse-tree.cc                |   21 +
 gcc/fortran/gfortran.h                        |   20 +-
 gcc/fortran/io.cc                             |    2 +-
 gcc/fortran/match.h                           |    2 +
 gcc/fortran/openmp.cc                         |  294 ++-
 gcc/fortran/parse.cc                          |  571 +++--
 gcc/fortran/parse.h                           |    8 +-
 gcc/fortran/resolve.cc                        |    6 +
 gcc/fortran/st.cc                             |    4 +
 gcc/fortran/symbol.cc                         |   25 +-
 gcc/fortran/trans-decl.cc                     |    5 +-
 gcc/fortran/trans-openmp.cc                   |  238 +-
 gcc/fortran/trans-stmt.h                      |    1 +
 gcc/fortran/trans.cc                          |    1 +
 gcc/fortran/types.def                         |    2 +
 gcc/gimple-low.cc                             |   36 +
 gcc/gimple-pretty-print.cc                    |   64 +
 gcc/gimple-streamer-in.cc                     |   13 +
 gcc/gimple-streamer-out.cc                    |   10 +
 gcc/gimple-walk.cc                            |   28 +
 gcc/gimple.cc                                 |   36 +
 gcc/gimple.def                                |    8 +
 gcc/gimple.h                                  |  122 +-
 gcc/gimplify.cc                               |  574 +++--
 gcc/gimplify.h                                |    2 +-
 gcc/gsstruct.def                              |    2 +
 gcc/ipa-free-lang-data.cc                     |    2 +-
 gcc/ipa.cc                                    |    3 -
 gcc/lto-cgraph.cc                             |   12 +-
 gcc/lto-streamer-out.cc                       |    3 +-
 gcc/lto-streamer.h                            |    6 -
 gcc/lto/lto-partition.cc                      |    5 +-
 gcc/omp-builtins.def                          |    3 +
 gcc/omp-expand.cc                             |   32 +-
 gcc/omp-general.cc                            | 2033 +++++++++--------
 gcc/omp-general.h                             |   50 +-
 gcc/omp-low.cc                                |   83 +
 gcc/omp-offload.cc                            |  117 +-
 gcc/omp-simd-clone.cc                         |    3 +-
 gcc/passes.cc                                 |    3 +-
 gcc/symtab.cc                                 |    2 +-
 .../gomp/declare-target-indirect-2.c          |   10 +-
 .../c-c++-common/gomp/declare-variant-10.c    |    4 +-
 .../c-c++-common/gomp/declare-variant-12.c    |   14 +-
 .../c-c++-common/gomp/declare-variant-13.c    |    6 +-
 .../c-c++-common/gomp/declare-variant-2.c     |    4 +-
 .../c-c++-common/gomp/declare-variant-3.c     |   10 +-
 .../c-c++-common/gomp/declare-variant-8.c     |    4 +-
 .../c-c++-common/gomp/declare-variant-9.c     |    4 +-
 .../c-c++-common/gomp/declare-variant-any.c   |   10 +
 .../gomp/declare-variant-arg-exprs.c          |   29 +
 .../gomp/declare-variant-dynamic-1.c          |   26 +
 .../gomp/declare-variant-dynamic-2.c          |   30 +
 .../c-c++-common/gomp/metadirective-1.c       |   52 +
 .../c-c++-common/gomp/metadirective-2.c       |   74 +
 .../c-c++-common/gomp/metadirective-3.c       |   21 +
 .../c-c++-common/gomp/metadirective-4.c       |   40 +
 .../c-c++-common/gomp/metadirective-5.c       |   24 +
 .../c-c++-common/gomp/metadirective-6.c       |   31 +
 .../c-c++-common/gomp/metadirective-7.c       |   31 +
 .../c-c++-common/gomp/metadirective-8.c       |   16 +
 .../gomp/metadirective-construct.c            |  177 ++
 .../c-c++-common/gomp/metadirective-device.c  |  147 ++
 .../gomp/metadirective-no-score.c             |   95 +
 .../gomp/metadirective-target-device.c        |  147 ++
 .../c-c++-common/gomp/reverse-offload-1.c     |    2 +-
 .../g++.dg/gomp/attrs-metadirective-1.C       |   40 +
 .../g++.dg/gomp/attrs-metadirective-2.C       |   74 +
 .../g++.dg/gomp/attrs-metadirective-3.C       |   19 +
 .../g++.dg/gomp/attrs-metadirective-4.C       |   41 +
 .../g++.dg/gomp/attrs-metadirective-5.C       |   24 +
 .../g++.dg/gomp/attrs-metadirective-6.C       |   31 +
 .../g++.dg/gomp/attrs-metadirective-7.C       |   31 +
 .../g++.dg/gomp/attrs-metadirective-8.C       |   16 +
 .../g++.dg/gomp/declare-variant-class-1.C     |   32 +
 .../g++.dg/gomp/declare-variant-class-2.C     |   37 +
 gcc/testsuite/gcc.dg/gomp/metadirective-1.c   |   15 +
 .../gfortran.dg/gomp/declare-variant-10.f90   |    4 +-
 .../gfortran.dg/gomp/declare-variant-12.f90   |   14 +-
 .../gfortran.dg/gomp/declare-variant-13.f90   |   28 +-
 .../gfortran.dg/gomp/declare-variant-3.f90    |   12 +-
 .../gfortran.dg/gomp/declare-variant-8.f90    |   12 +-
 .../gfortran.dg/gomp/declare-variant-9.f90    |    2 +-
 .../gfortran.dg/gomp/declare-variant-any.f90  |   28 +
 .../gfortran.dg/gomp/metadirective-1.f90      |   73 +
 .../gfortran.dg/gomp/metadirective-10.f90     |   40 +
 .../gfortran.dg/gomp/metadirective-11.f90     |   33 +
 .../gfortran.dg/gomp/metadirective-2.f90      |   62 +
 .../gfortran.dg/gomp/metadirective-3.f90      |   24 +
 .../gfortran.dg/gomp/metadirective-4.f90      |   39 +
 .../gfortran.dg/gomp/metadirective-5.f90      |   30 +
 .../gfortran.dg/gomp/metadirective-6.f90      |   31 +
 .../gfortran.dg/gomp/metadirective-7.f90      |   36 +
 .../gfortran.dg/gomp/metadirective-8.f90      |   22 +
 .../gfortran.dg/gomp/metadirective-9.f90      |   30 +
 .../gomp/metadirective-construct.f90          |  260 +++
 .../gomp/metadirective-no-score.f90           |  122 +
 gcc/testsuite/gfortran.dg/gomp/pure-1.f90     |    7 +
 gcc/testsuite/gfortran.dg/gomp/pure-2.f90     |    8 -
 gcc/tree-cfg.cc                               |   24 +
 gcc/tree-inline.cc                            |   45 +-
 gcc/tree-pretty-print.cc                      |   36 +-
 gcc/tree-pretty-print.h                       |    2 +
 gcc/tree-ssa-operands.cc                      |   17 +
 gcc/tree.def                                  |    6 +
 gcc/tree.h                                    |    3 +
 include/cuda/cuda.h                           |    2 +
 libgomp/Makefile.am                           |    2 +-
 libgomp/Makefile.in                           |    5 +-
 libgomp/config/gcn/selector.c                 |  102 +
 libgomp/config/linux/selector.c               |   65 +
 libgomp/config/linux/x86/selector.c           |  406 ++++
 libgomp/config/nvptx/selector.c               |   77 +
 libgomp/libgomp-plugin.h                      |    2 +
 libgomp/libgomp.h                             |    1 +
 libgomp/libgomp.map                           |    5 +
 libgomp/libgomp.texi                          |   39 +-
 libgomp/libgomp_g.h                           |    8 +
 libgomp/oacc-host.c                           |   11 +
 libgomp/plugin/plugin-gcn.c                   |   52 +
 libgomp/plugin/plugin-nvptx.c                 |   82 +
 libgomp/selector.c                            |   64 +
 libgomp/target.c                              |   40 +
 .../libgomp.c++/metadirective-template-1.C    |   37 +
 .../libgomp.c++/metadirective-template-2.C    |   41 +
 .../libgomp.c++/metadirective-template-3.C    |   41 +
 .../libgomp.c-c++-common/metadirective-1.c    |   35 +
 .../libgomp.c-c++-common/metadirective-2.c    |   41 +
 .../libgomp.c-c++-common/metadirective-3.c    |   34 +
 .../libgomp.c-c++-common/metadirective-4.c    |   52 +
 .../libgomp.c-c++-common/metadirective-5.c    |   46 +
 .../libgomp.fortran/metadirective-1.f90       |   61 +
 .../libgomp.fortran/metadirective-2.f90       |   40 +
 .../libgomp.fortran/metadirective-3.f90       |   29 +
 .../libgomp.fortran/metadirective-4.f90       |   46 +
 .../libgomp.fortran/metadirective-5.f90       |   44 +
 .../libgomp.fortran/metadirective-6.f90       |   58 +
 160 files changed, 8115 insertions(+), 1655 deletions(-)
 create mode 100644 gcc/testsuite/c-c++-common/gomp/declare-variant-any.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/declare-variant-arg-exprs.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/declare-variant-dynamic-1.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/declare-variant-dynamic-2.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-1.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-2.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-3.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-4.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-5.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-6.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-7.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-8.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-construct.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-device.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-no-score.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/metadirective-target-device.c
 create mode 100644 gcc/testsuite/g++.dg/gomp/attrs-metadirective-1.C
 create mode 100644 gcc/testsuite/g++.dg/gomp/attrs-metadirective-2.C
 create mode 100644 gcc/testsuite/g++.dg/gomp/attrs-metadirective-3.C
 create mode 100644 gcc/testsuite/g++.dg/gomp/attrs-metadirective-4.C
 create mode 100644 gcc/testsuite/g++.dg/gomp/attrs-metadirective-5.C
 create mode 100644 gcc/testsuite/g++.dg/gomp/attrs-metadirective-6.C
 create mode 100644 gcc/testsuite/g++.dg/gomp/attrs-metadirective-7.C
 create mode 100644 gcc/testsuite/g++.dg/gomp/attrs-metadirective-8.C
 create mode 100644 gcc/testsuite/g++.dg/gomp/declare-variant-class-1.C
 create mode 100644 gcc/testsuite/g++.dg/gomp/declare-variant-class-2.C
 create mode 100644 gcc/testsuite/gcc.dg/gomp/metadirective-1.c
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/declare-variant-any.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-1.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-10.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-11.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-2.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-3.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-4.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-5.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-6.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-7.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-8.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-9.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-construct.f90
 create mode 100644 gcc/testsuite/gfortran.dg/gomp/metadirective-no-score.f90
 create mode 100644 libgomp/config/gcn/selector.c
 create mode 100644 libgomp/config/linux/selector.c
 create mode 100644 libgomp/config/linux/x86/selector.c
 create mode 100644 libgomp/config/nvptx/selector.c
 create mode 100644 libgomp/selector.c
 create mode 100644 libgomp/testsuite/libgomp.c++/metadirective-template-1.C
 create mode 100644 libgomp/testsuite/libgomp.c++/metadirective-template-2.C
 create mode 100644 libgomp/testsuite/libgomp.c++/metadirective-template-3.C
 create mode 100644 libgomp/testsuite/libgomp.c-c++-common/metadirective-1.c
 create mode 100644 libgomp/testsuite/libgomp.c-c++-common/metadirective-2.c
 create mode 100644 libgomp/testsuite/libgomp.c-c++-common/metadirective-3.c
 create mode 100644 libgomp/testsuite/libgomp.c-c++-common/metadirective-4.c
 create mode 100644 libgomp/testsuite/libgomp.c-c++-common/metadirective-5.c
 create mode 100644 libgomp/testsuite/libgomp.fortran/metadirective-1.f90
 create mode 100644 libgomp/testsuite/libgomp.fortran/metadirective-2.f90
 create mode 100644 libgomp/testsuite/libgomp.fortran/metadirective-3.f90
 create mode 100644 libgomp/testsuite/libgomp.fortran/metadirective-4.f90
 create mode 100644 libgomp/testsuite/libgomp.fortran/metadirective-5.f90
 create mode 100644 libgomp/testsuite/libgomp.fortran/metadirective-6.f90