openmp: Add omp_all_memory support (C/C++ only so far)

The ugly part is that OpenMP 5.1 made omp_all_memory a reserved identifier
which isn't allowed to be used anywhere but in the depend clause, this is
against how everything else has been handled in OpenMP so far (where
some identifiers could have special meaning in some OpenMP clauses or
pragmas but not elsewhere).
The patch handles it by making it a conditional keyword (for -fopenmp
only) and emitting a better diagnostics when it is used in a primary
expression.  Having a nicer diagnostics when e.g. trying to do
int omp_all_memory;
or
int *omp_all_memory[10];
etc. would mean changing too many spots and hooking into name lookups
to reject declaring any such symbols would be too ugly and I'm afraid
there are way too many spots where one can introduce a name
(variables, functions, namespaces, struct, enum, enumerators, template
arguments, ...).

Otherwise, the handling is quite simple, normal depend clauses lower
into addresses of variables being handed over to the library, for
omp_all_memory I'm using NULL pointers.  omp_all_memory can only be
used with inout or out depend kinds and means that a task is dependent
on all previously created sibling tasks that have any dependency (of
any depend kind) and that any later created sibling tasks will be
dependent on it if they have any dependency.

2022-05-12  Jakub Jelinek  <jakub@redhat.com>

gcc/
	* gimplify.cc (gimplify_omp_depend): Don't build_fold_addr_expr
	if null_pointer_node.
	(gimplify_scan_omp_clauses): Likewise.
	* tree-pretty-print.cc (dump_omp_clause): Print null_pointer_node
	as omp_all_memory.
gcc/c-family/
	* c-common.h (enum rid): Add RID_OMP_ALL_MEMORY.
	* c-omp.cc (c_finish_omp_depobj): Don't build_fold_addr_expr
	if null_pointer_node.
gcc/c/
	* c-parser.cc (c_parse_init): Register omp_all_memory as keyword
	if flag_openmp.
	(c_parser_postfix_expression): Diagnose uses of omp_all_memory
	in postfix expressions.
	(c_parser_omp_variable_list): Handle omp_all_memory in depend
	clause.
	* c-typeck.cc (c_finish_omp_clauses): Handle omp_all_memory
	keyword in depend clause as null_pointer_node, diagnose invalid
	uses.
gcc/cp/
	* lex.cc (init_reswords): Register omp_all_memory as keyword
	if flag_openmp.
	* parser.cc (cp_parser_primary_expression): Diagnose uses of
	omp_all_memory in postfix expressions.
	(cp_parser_omp_var_list_no_open): Handle omp_all_memory in depend
	clause.
	* semantics.cc (finish_omp_clauses): Handle omp_all_memory
	keyword in depend clause as null_pointer_node, diagnose invalid
	uses.
	* pt.cc (tsubst_omp_clause_decl): Pass through omp_all_memory.
gcc/testsuite/
	* c-c++-common/gomp/all-memory-1.c: New test.
	* c-c++-common/gomp/all-memory-2.c: New test.
	* c-c++-common/gomp/all-memory-3.c: New test.
	* g++.dg/gomp/all-memory-1.C: New test.
	* g++.dg/gomp/all-memory-2.C: New test.
libgomp/
	* libgomp.h (struct gomp_task): Add depend_all_memory member.
	* task.c (gomp_init_task): Initialize depend_all_memory.
	(gomp_task_handle_depend): Handle omp_all_memory.
	(gomp_task_run_post_handle_depend_hash): Clear
	parent->depend_all_memory if equal to current task.
	(gomp_task_maybe_wait_for_dependencies): Handle omp_all_memory.
	* testsuite/libgomp.c-c++-common/depend-1.c: New test.
	* testsuite/libgomp.c-c++-common/depend-2.c: New test.
	* testsuite/libgomp.c-c++-common/depend-3.c: New test.

5 files changed, 179 insertions, 0 deletions

diff --git a/gcc/testsuite/c-c++-common/gomp/all-memory-1.c b/gcc/testsuite/c-c++-common/gomp/all-memory-1.c
new file mode 100644
index 0000000..5d63e0d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/all-memory-1.c
@@ -0,0 +1,52 @@
+int omp_all_memory;			/* { dg-error "expected" } */
+
+void
+foo (void)
+{
+  int p = (&omp_all_memory)[0];		/* { dg-error "'omp_all_memory' may only be used in OpenMP 'depend' clause" } */
+}
+
+void
+bar (void)
+{
+  int *omp_all_memory;			/* { dg-error "expected" } */
+}
+
+void
+baz (void)
+{
+  struct omp_all_memory { int a; };	/* { dg-error "expected" } */
+}
+
+void
+qux (void)
+{
+  union omp_all_memory { int a; };	/* { dg-error "expected" } */
+}
+
+void
+corge (void)
+{
+  enum omp_all_memory { OAM; };		/* { dg-error "expected" } */
+}
+
+void
+garply (void)
+{
+  enum E { omp_all_memory }; }		/* { dg-error "expected" } */
+
+void
+boo (void)
+{
+  int x, y;
+  #pragma omp task private (omp_all_memory)			/* { dg-error "expected" } */
+  ;
+  #pragma omp task depend(inout: *&omp_all_memory)		/* { dg-error "'omp_all_memory' may only be used in OpenMP 'depend' clause" } */
+  ;
+  #pragma omp task depend(inout: omp_all_memory[0])		/* { dg-error "'omp_all_memory' may only be used in OpenMP 'depend' clause" } */
+  ;
+  #pragma omp task depend(in: omp_all_memory)			/* { dg-error "'omp_all_memory' used with 'depend' kind other than 'out' or 'inout'" } */
+  ;
+  #pragma omp task depend(mutexinoutset: omp_all_memory)	/* { dg-error "'omp_all_memory' used with 'depend' kind other than 'out' or 'inout'" } */
+  ;
+}
diff --git a/gcc/testsuite/c-c++-common/gomp/all-memory-2.c b/gcc/testsuite/c-c++-common/gomp/all-memory-2.c
new file mode 100644
index 0000000..6f5d31b
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/all-memory-2.c
@@ -0,0 +1,55 @@
+/* { dg-options "-fno-openmp" } */
+
+int omp_all_memory;			/* { dg-bogus "expected" } */
+
+void
+foo (void)
+{
+  int p = (&omp_all_memory)[0];		/* { dg-bogus "'omp_all_memory' may only be used in OpenMP 'depend' clause" } */
+}
+
+void
+bar (void)
+{
+  int *omp_all_memory;			/* { dg-bogus "expected" } */
+}
+
+void
+baz (void)
+{
+  struct omp_all_memory { int a; };	/* { dg-bogus "expected" } */
+}
+
+void
+qux (void)
+{
+  union omp_all_memory { int a; };	/* { dg-bogus "expected" } */
+}
+
+void
+corge (void)
+{
+  enum omp_all_memory { OAM };		/* { dg-bogus "expected" } */
+}
+
+void
+garply (void)
+{
+  enum E { omp_all_memory };		/* { dg-bogus "expected" } */
+}
+
+void
+boo (void)
+{
+  int x, y;
+  #pragma omp task private (omp_all_memory)
+  ;
+  #pragma omp task depend(inout: *&omp_all_memory)
+  ;
+  #pragma omp task depend(inout: omp_all_memory[0])
+  ;
+  #pragma omp task depend(in: omp_all_memory)
+  ;
+  #pragma omp task depend(mutexinoutset: omp_all_memory)
+  ;
+}
diff --git a/gcc/testsuite/c-c++-common/gomp/all-memory-3.c b/gcc/testsuite/c-c++-common/gomp/all-memory-3.c
new file mode 100644
index 0000000..f178b8d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/all-memory-3.c
@@ -0,0 +1,22 @@
+typedef struct __attribute__((__aligned__ (sizeof (void *)))) omp_depend_t {
+  char __omp_depend_t__[2 * sizeof (void *)];
+} omp_depend_t;
+
+omp_depend_t z;
+
+void
+foo (void)
+{
+  int x = 0, y = 0;
+  #pragma omp task depend(out: omp_all_memory)
+  ;
+  #pragma omp task depend(inout: omp_all_memory)
+  ;
+  #pragma omp task depend(out: x, omp_all_memory, y)
+  ;
+  #pragma omp task depend(inout: omp_all_memory, y)
+  ;
+  #pragma omp task depend(out: x, omp_all_memory)
+  ;
+  #pragma omp depobj (z) depend (inout: omp_all_memory)
+}
diff --git a/gcc/testsuite/g++.dg/gomp/all-memory-1.C b/gcc/testsuite/g++.dg/gomp/all-memory-1.C
new file mode 100644
index 0000000..8f3358d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/gomp/all-memory-1.C
@@ -0,0 +1,24 @@
+namespace A
+{
+  namespace omp_all_memory		// { dg-error "expected" }
+  {
+  }
+}
+
+namespace B
+{
+  template <int N>
+  void omp_all_memory () {}		// { dg-error "expected" }
+}
+
+namespace C
+{
+  template <int N>
+  struct omp_all_memory {};		// { dg-error "expected" }
+}
+
+namespace D
+{
+  template <int omp_all_memory>		// { dg-error "expected" }
+  struct S {};
+}
diff --git a/gcc/testsuite/g++.dg/gomp/all-memory-2.C b/gcc/testsuite/g++.dg/gomp/all-memory-2.C
new file mode 100644
index 0000000..1acf391
--- /dev/null
+++ b/gcc/testsuite/g++.dg/gomp/all-memory-2.C
@@ -0,0 +1,26 @@
+// { dg-options "-fno-openmp" }
+
+namespace A
+{
+  namespace omp_all_memory		// { dg-bogus "expected" }
+  {
+  }
+}
+
+namespace B
+{
+  template <int N>
+  void omp_all_memory () {}		// { dg-bogus "expected" }
+}
+
+namespace C
+{
+  template <int N>
+  struct omp_all_memory {};		// { dg-bogus "expected" }
+}
+
+namespace D
+{
+  template <int omp_all_memory>		// { dg-bogus "expected" }
+  struct S {};
+}