public inbox for gcc-cvs@sourceware.org
help / color / mirror / Atom feed
* [gcc r12-3654] openmp: Allow private or firstprivate arguments to default clause even for C/C++
@ 2021-09-18 7:49 Jakub Jelinek
0 siblings, 0 replies; only message in thread
From: Jakub Jelinek @ 2021-09-18 7:49 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:e5597f2ad55219092929dc12ea15e1edba06df18
commit r12-3654-ge5597f2ad55219092929dc12ea15e1edba06df18
Author: Jakub Jelinek <jakub@redhat.com>
Date: Sat Sep 18 09:47:25 2021 +0200
openmp: Allow private or firstprivate arguments to default clause even for C/C++
OpenMP 5.1 allows default(private) or default(firstprivate) even in C/C++,
but it behaves the same way as in Fortran only for variables not declared at
namespace or file scope. For the namespace/file scope variables it instead
behaves as default(none).
2021-09-18 Jakub Jelinek <jakub@redhat.com>
gcc/
* gimplify.c (omp_default_clause): For C/C++ default({,first}private),
if file/namespace scope variable doesn't have predetermined sharing,
treat it as if there was default(none).
gcc/c/
* c-parser.c (c_parser_omp_clause_default): Handle private and
firstprivate arguments, adjust diagnostics on unknown argument.
gcc/cp/
* parser.c (cp_parser_omp_clause_default): Handle private and
firstprivate arguments, adjust diagnostics on unknown argument.
* cp-gimplify.c (cxx_omp_finish_clause): Handle OMP_CLAUSE_PRIVATE.
gcc/testsuite/
* c-c++-common/gomp/default-2.c: New test.
* c-c++-common/gomp/default-3.c: New test.
* g++.dg/gomp/default-1.C: New test.
libgomp/
* testsuite/libgomp.c++/default-1.C: New test.
* testsuite/libgomp.c-c++-common/default-1.c: New test.
* libgomp.texi (OpenMP 5.1): Mark "private and firstprivate argument
to default clause in C and C++" as implemented.
Diff:
---
gcc/c/c-parser.c | 25 ++++-
gcc/cp/cp-gimplify.c | 4 +-
gcc/cp/parser.c | 19 +++-
gcc/gimplify.c | 12 +++
gcc/testsuite/c-c++-common/gomp/default-2.c | 67 ++++++++++++
gcc/testsuite/c-c++-common/gomp/default-3.c | 14 +++
gcc/testsuite/g++.dg/gomp/default-1.C | 112 +++++++++++++++++++++
libgomp/libgomp.texi | 2 +-
libgomp/testsuite/libgomp.c++/default-1.C | 29 ++++++
libgomp/testsuite/libgomp.c-c++-common/default-1.c | 25 +++++
10 files changed, 302 insertions(+), 7 deletions(-)
diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
index eba9bbf5ec7..c5e222bfeef 100644
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -13420,6 +13420,9 @@ c_parser_omp_clause_copyprivate (c_parser *parser, tree list)
/* OpenMP 2.5:
default ( none | shared )
+ OpenMP 5.1:
+ default ( private | firstprivate )
+
OpenACC:
default ( none | present ) */
@@ -13446,9 +13449,24 @@ c_parser_omp_clause_default (c_parser *parser, tree list, bool is_oacc)
break;
case 'p':
- if (strcmp ("present", p) != 0 || !is_oacc)
+ if (is_oacc)
+ {
+ if (strcmp ("present", p) != 0)
+ goto invalid_kind;
+ kind = OMP_CLAUSE_DEFAULT_PRESENT;
+ }
+ else
+ {
+ if (strcmp ("private", p) != 0)
+ goto invalid_kind;
+ kind = OMP_CLAUSE_DEFAULT_PRIVATE;
+ }
+ break;
+
+ case 'f':
+ if (strcmp ("firstprivate", p) != 0 || is_oacc)
goto invalid_kind;
- kind = OMP_CLAUSE_DEFAULT_PRESENT;
+ kind = OMP_CLAUSE_DEFAULT_FIRSTPRIVATE;
break;
case 's':
@@ -13469,7 +13487,8 @@ c_parser_omp_clause_default (c_parser *parser, tree list, bool is_oacc)
if (is_oacc)
c_parser_error (parser, "expected %<none%> or %<present%>");
else
- c_parser_error (parser, "expected %<none%> or %<shared%>");
+ c_parser_error (parser, "expected %<none%>, %<shared%>, "
+ "%<private%> or %<firstprivate%>");
}
parens.skip_until_found_close (parser);
diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
index bf928a82ce9..c86a5fefa68 100644
--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -2060,6 +2060,7 @@ cxx_omp_finish_clause (tree c, gimple_seq *, bool /* openacc */)
bool make_shared = false;
if (OMP_CLAUSE_CODE (c) != OMP_CLAUSE_FIRSTPRIVATE
+ && OMP_CLAUSE_CODE (c) != OMP_CLAUSE_PRIVATE
&& (OMP_CLAUSE_CODE (c) != OMP_CLAUSE_LASTPRIVATE
|| !OMP_CLAUSE_LASTPRIVATE_LOOP_IV (c)))
return;
@@ -2080,9 +2081,10 @@ cxx_omp_finish_clause (tree c, gimple_seq *, bool /* openacc */)
Save the results, because later we won't be in the right context
for making these queries. */
bool first = OMP_CLAUSE_CODE (c) == OMP_CLAUSE_FIRSTPRIVATE;
+ bool last = OMP_CLAUSE_CODE (c) == OMP_CLAUSE_LASTPRIVATE;
if (!make_shared
&& CLASS_TYPE_P (inner_type)
- && cxx_omp_create_clause_info (c, inner_type, !first, first, !first,
+ && cxx_omp_create_clause_info (c, inner_type, !first, first, last,
true))
make_shared = true;
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 31bae6d8983..b9ed38dbafb 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -36988,6 +36988,9 @@ cp_parser_omp_clause_collapse (cp_parser *parser, tree list, location_t location
/* OpenMP 2.5:
default ( none | shared )
+ OpenMP 5.1:
+ default ( private | firstprivate )
+
OpenACC:
default ( none | present ) */
@@ -37001,7 +37004,12 @@ cp_parser_omp_clause_default (cp_parser *parser, tree list,
matching_parens parens;
if (!parens.require_open (parser))
return list;
- if (cp_lexer_next_token_is (parser->lexer, CPP_NAME))
+ if (!is_oacc && cp_lexer_next_token_is_keyword (parser->lexer, RID_PRIVATE))
+ {
+ kind = OMP_CLAUSE_DEFAULT_PRIVATE;
+ cp_lexer_consume_token (parser->lexer);
+ }
+ else if (cp_lexer_next_token_is (parser->lexer, CPP_NAME))
{
tree id = cp_lexer_peek_token (parser->lexer)->u.value;
const char *p = IDENTIFIER_POINTER (id);
@@ -37020,6 +37028,12 @@ cp_parser_omp_clause_default (cp_parser *parser, tree list,
kind = OMP_CLAUSE_DEFAULT_PRESENT;
break;
+ case 'f':
+ if (strcmp ("firstprivate", p) != 0 || is_oacc)
+ goto invalid_kind;
+ kind = OMP_CLAUSE_DEFAULT_FIRSTPRIVATE;
+ break;
+
case 's':
if (strcmp ("shared", p) != 0 || is_oacc)
goto invalid_kind;
@@ -37038,7 +37052,8 @@ cp_parser_omp_clause_default (cp_parser *parser, tree list,
if (is_oacc)
cp_parser_error (parser, "expected %<none%> or %<present%>");
else
- cp_parser_error (parser, "expected %<none%> or %<shared%>");
+ cp_parser_error (parser, "expected %<none%>, %<shared%>, "
+ "%<private%> or %<firstprivate%>");
}
if (kind == OMP_CLAUSE_DEFAULT_UNSPECIFIED
diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index f680292fd91..9163dcda438 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -7369,6 +7369,18 @@ omp_default_clause (struct gimplify_omp_ctx *ctx, tree decl,
default_kind = kind;
else if (VAR_P (decl) && TREE_STATIC (decl) && DECL_IN_CONSTANT_POOL (decl))
default_kind = OMP_CLAUSE_DEFAULT_SHARED;
+ /* For C/C++ default({,first}private), variables with static storage duration
+ declared in a namespace or global scope and referenced in construct
+ must be explicitly specified, i.e. acts as default(none). */
+ else if ((default_kind == OMP_CLAUSE_DEFAULT_PRIVATE
+ || default_kind == OMP_CLAUSE_DEFAULT_FIRSTPRIVATE)
+ && VAR_P (decl)
+ && is_global_var (decl)
+ && (DECL_FILE_SCOPE_P (decl)
+ || (DECL_CONTEXT (decl)
+ && TREE_CODE (DECL_CONTEXT (decl)) == NAMESPACE_DECL))
+ && !lang_GNU_Fortran ())
+ default_kind = OMP_CLAUSE_DEFAULT_NONE;
switch (default_kind)
{
diff --git a/gcc/testsuite/c-c++-common/gomp/default-2.c b/gcc/testsuite/c-c++-common/gomp/default-2.c
new file mode 100644
index 00000000000..6378e6e804c
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/default-2.c
@@ -0,0 +1,67 @@
+int x;
+extern int z;
+
+void
+foo (void)
+{
+ int y = 0, i;
+ static int w;
+ #pragma omp task default(firstprivate) /* { dg-message "note: enclosing 'task'" } */
+ {
+ y++; /* { dg-bogus "'y' not specified in enclosing 'task'" } */
+ w++; /* { dg-bogus "'w' not specified in enclosing 'task'" } */
+ x++; /* { dg-error "'x' not specified in enclosing 'task'" } */
+ z++; /* { dg-error "'z' not specified in enclosing 'task'" } */
+ }
+ #pragma omp taskloop default(firstprivate) /* { dg-message "note: enclosing 'taskloop'" } */
+ for (i = 0; i < 64; i++)
+ {
+ y++; /* { dg-bogus "'y' not specified in enclosing 'taskloop'" } */
+ w++; /* { dg-bogus "'w' not specified in enclosing 'taskloop'" } */
+ x++; /* { dg-error "'x' not specified in enclosing 'taskloop'" } */
+ z++; /* { dg-error "'z' not specified in enclosing 'taskloop'" } */
+ }
+ #pragma omp teams default(firstprivate) /* { dg-message "note: enclosing 'teams'" } */
+ {
+ y++; /* { dg-bogus "'y' not specified in enclosing 'teams'" } */
+ w++; /* { dg-bogus "'w' not specified in enclosing 'teams'" } */
+ x++; /* { dg-error "'x' not specified in enclosing 'teams'" } */
+ z++; /* { dg-error "'z' not specified in enclosing 'teams'" } */
+ }
+ #pragma omp parallel default(firstprivate) /* { dg-message "note: enclosing 'parallel'" } */
+ {
+ y++; /* { dg-bogus "'y' not specified in enclosing 'parallel'" } */
+ w++; /* { dg-bogus "'w' not specified in enclosing 'parallel'" } */
+ x++; /* { dg-error "'x' not specified in enclosing 'parallel'" } */
+ z++; /* { dg-error "'z' not specified in enclosing 'parallel'" } */
+ }
+ #pragma omp task default(private) /* { dg-message "note: enclosing 'task'" } */
+ {
+ y = 1; /* { dg-bogus "'y' not specified in enclosing 'task'" } */
+ w = 1; /* { dg-bogus "'w' not specified in enclosing 'task'" } */
+ x++; /* { dg-error "'x' not specified in enclosing 'task'" } */
+ z++; /* { dg-error "'z' not specified in enclosing 'task'" } */
+ }
+ #pragma omp taskloop default(private) /* { dg-message "note: enclosing 'taskloop'" } */
+ for (i = 0; i < 64; i++)
+ {
+ y = 1; /* { dg-bogus "'y' not specified in enclosing 'taskloop'" } */
+ w = 1; /* { dg-bogus "'w' not specified in enclosing 'taskloop'" } */
+ x++; /* { dg-error "'x' not specified in enclosing 'taskloop'" } */
+ z++; /* { dg-error "'z' not specified in enclosing 'taskloop'" } */
+ }
+ #pragma omp teams default(private) /* { dg-message "note: enclosing 'teams'" } */
+ {
+ y = 1; /* { dg-bogus "'y' not specified in enclosing 'teams'" } */
+ w = 1; /* { dg-bogus "'w' not specified in enclosing 'teams'" } */
+ x++; /* { dg-error "'x' not specified in enclosing 'teams'" } */
+ z++; /* { dg-error "'z' not specified in enclosing 'teams'" } */
+ }
+ #pragma omp parallel default(private) /* { dg-message "note: enclosing 'parallel'" } */
+ {
+ y = 1; /* { dg-bogus "'y' not specified in enclosing 'parallel'" } */
+ w++; /* { dg-bogus "'w' not specified in enclosing 'parallel'" } */
+ x++; /* { dg-error "'x' not specified in enclosing 'parallel'" } */
+ z++; /* { dg-error "'z' not specified in enclosing 'parallel'" } */
+ }
+}
diff --git a/gcc/testsuite/c-c++-common/gomp/default-3.c b/gcc/testsuite/c-c++-common/gomp/default-3.c
new file mode 100644
index 00000000000..a742a7105e9
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/default-3.c
@@ -0,0 +1,14 @@
+void
+foo (void)
+{
+ int i;
+ #pragma omp task default(copyprivate) /* { dg-error "expected 'none', 'shared', 'private' or 'firstprivate' before 'copyprivate'" } */
+ ;
+ #pragma omp taskloop default(copyprivate) /* { dg-error "expected 'none', 'shared', 'private' or 'firstprivate' before 'copyprivate'" } */
+ for (i = 0; i < 64; i++)
+ ;
+ #pragma omp teams default(copyprivate) /* { dg-error "expected 'none', 'shared', 'private' or 'firstprivate' before 'copyprivate'" } */
+ ;
+ #pragma omp parallel default(copyprivate) /* { dg-error "expected 'none', 'shared', 'private' or 'firstprivate' before 'copyprivate'" } */
+ ;
+}
diff --git a/gcc/testsuite/g++.dg/gomp/default-1.C b/gcc/testsuite/g++.dg/gomp/default-1.C
new file mode 100644
index 00000000000..e39df12837d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/gomp/default-1.C
@@ -0,0 +1,112 @@
+namespace N
+{
+ int x;
+ extern int z;
+}
+
+struct S
+{
+ static int s;
+};
+
+#if __cpp_variable_templates >= 201304
+template <int N>
+int t = N;
+#endif
+
+void
+foo (void)
+{
+ int y = 0, i;
+ static int w;
+ #pragma omp task default(firstprivate) /* { dg-message "note: enclosing 'task'" } */
+ {
+ y++; /* { dg-bogus "'y' not specified in enclosing 'task'" } */
+ w++; /* { dg-bogus "'w' not specified in enclosing 'task'" } */
+ S::s++; /* { dg-bogus "'S::s' not specified in enclosing 'task'" } */
+ N::x++; /* { dg-error "'x' not specified in enclosing 'task'" } */
+ N::z++; /* { dg-error "'z' not specified in enclosing 'task'" } */
+#if __cpp_variable_templates >= 201304
+ t<5>++; /* { dg-error "'t' not specified in enclosing 'task'" "" { target c++14 } } */
+#endif
+ }
+ #pragma omp taskloop default(firstprivate) /* { dg-message "note: enclosing 'taskloop'" } */
+ for (i = 0; i < 64; i++)
+ {
+ y++; /* { dg-bogus "'y' not specified in enclosing 'taskloop'" } */
+ w++; /* { dg-bogus "'w' not specified in enclosing 'taskloop'" } */
+ S::s++; /* { dg-bogus "'S::s' not specified in enclosing 'taskloop'" } */
+ N::x++; /* { dg-error "'x' not specified in enclosing 'taskloop'" } */
+ N::z++; /* { dg-error "'z' not specified in enclosing 'taskloop'" } */
+#if __cpp_variable_templates >= 201304
+ t<5>++; /* { dg-error "'t' not specified in enclosing 'taskloop'" "" { target c++14 } } */
+#endif
+ }
+ #pragma omp teams default(firstprivate) /* { dg-message "note: enclosing 'teams'" } */
+ {
+ y++; /* { dg-bogus "'y' not specified in enclosing 'teams'" } */
+ w++; /* { dg-bogus "'w' not specified in enclosing 'teams'" } */
+ S::s++; /* { dg-bogus "'S::s' not specified in enclosing 'teams'" } */
+ N::x++; /* { dg-error "'x' not specified in enclosing 'teams'" } */
+ N::z++; /* { dg-error "'z' not specified in enclosing 'teams'" } */
+#if __cpp_variable_templates >= 201304
+ t<5>++; /* { dg-error "'t' not specified in enclosing 'teams'" "" { target c++14 } } */
+#endif
+ }
+ #pragma omp parallel default(firstprivate) /* { dg-message "note: enclosing 'parallel'" } */
+ {
+ y++; /* { dg-bogus "'y' not specified in enclosing 'parallel'" } */
+ w++; /* { dg-bogus "'w' not specified in enclosing 'parallel'" } */
+ S::s++; /* { dg-bogus "'S::s' not specified in enclosing 'parallel'" } */
+ N::x++; /* { dg-error "'x' not specified in enclosing 'parallel'" } */
+ N::z++; /* { dg-error "'z' not specified in enclosing 'parallel'" } */
+#if __cpp_variable_templates >= 201304
+ t<5>++; /* { dg-error "'t' not specified in enclosing 'parallel'" "" { target c++14 } } */
+#endif
+ }
+ #pragma omp task default(private) /* { dg-message "note: enclosing 'task'" } */
+ {
+ y = 1; /* { dg-bogus "'y' not specified in enclosing 'task'" } */
+ w = 1; /* { dg-bogus "'w' not specified in enclosing 'task'" } */
+ S::s = 1; /* { dg-bogus "'S::s' not specified in enclosing 'task'" } */
+ N::x++; /* { dg-error "'x' not specified in enclosing 'task'" } */
+ N::z++; /* { dg-error "'z' not specified in enclosing 'task'" } */
+#if __cpp_variable_templates >= 201304
+ t<5>++; /* { dg-error "'t' not specified in enclosing 'task'" "" { target c++14 } } */
+#endif
+ }
+ #pragma omp taskloop default(private) /* { dg-message "note: enclosing 'taskloop'" } */
+ for (i = 0; i < 64; i++)
+ {
+ y = 1; /* { dg-bogus "'y' not specified in enclosing 'taskloop'" } */
+ w = 1; /* { dg-bogus "'w' not specified in enclosing 'taskloop'" } */
+ S::s = 1; /* { dg-bogus "'S::s' not specified in enclosing 'taskloop'" } */
+ N::x++; /* { dg-error "'x' not specified in enclosing 'taskloop'" } */
+ N::z++; /* { dg-error "'z' not specified in enclosing 'taskloop'" } */
+#if __cpp_variable_templates >= 201304
+ t<5>++; /* { dg-error "'t' not specified in enclosing 'taskloop'" "" { target c++14 } } */
+#endif
+ }
+ #pragma omp teams default(private) /* { dg-message "note: enclosing 'teams'" } */
+ {
+ y = 1; /* { dg-bogus "'y' not specified in enclosing 'teams'" } */
+ w = 1; /* { dg-bogus "'w' not specified in enclosing 'teams'" } */
+ S::s = 1; /* { dg-bogus "'S::s' not specified in enclosing 'teams'" } */
+ N::x++; /* { dg-error "'x' not specified in enclosing 'teams'" } */
+ N::z++; /* { dg-error "'z' not specified in enclosing 'teams'" } */
+#if __cpp_variable_templates >= 201304
+ t<5>++; /* { dg-error "'t' not specified in enclosing 'teams'" "" { target c++14 } } */
+#endif
+ }
+ #pragma omp parallel default(private) /* { dg-message "note: enclosing 'parallel'" } */
+ {
+ y = 1; /* { dg-bogus "'y' not specified in enclosing 'parallel'" } */
+ w = 1; /* { dg-bogus "'w' not specified in enclosing 'parallel'" } */
+ S::s = 1; /* { dg-bogus "'S::s' not specified in enclosing 'parallel'" } */
+ N::x++; /* { dg-error "'x' not specified in enclosing 'parallel'" } */
+ N::z++; /* { dg-error "'z' not specified in enclosing 'parallel'" } */
+#if __cpp_variable_templates >= 201304
+ t<5>++; /* { dg-error "'t' not specified in enclosing 'parallel'" "" { target c++14 } } */
+#endif
+ }
+}
diff --git a/libgomp/libgomp.texi b/libgomp/libgomp.texi
index 8bbb1e261b2..b3bab8feddf 100644
--- a/libgomp/libgomp.texi
+++ b/libgomp/libgomp.texi
@@ -305,7 +305,7 @@ The OpenMP 4.5 specification is fully supported.
@item @code{seq_cst} clause on a @code{flush} construct @tab Y @tab
@item @code{inoutset} argument to the @code{depend} clause @tab N @tab
@item @code{private} and @code{firstprivate} argument to @code{default}
- clause in C and C++ @tab N @tab
+ clause in C and C++ @tab Y @tab
@item @code{present} argument to @code{defaultmap} clause @tab N @tab
@item @code{omp_set_num_teams}, @code{omp_set_teams_thread_limit},
@code{omp_get_max_teams}, @code{omp_get_teams_thread_limit} runtime
diff --git a/libgomp/testsuite/libgomp.c++/default-1.C b/libgomp/testsuite/libgomp.c++/default-1.C
new file mode 100644
index 00000000000..3c03c2988b9
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c++/default-1.C
@@ -0,0 +1,29 @@
+#include <omp.h>
+#include <stdlib.h>
+
+struct S { S () : s (42) {} S (const S &x) : s (x.s) {}; ~S () {} int s; };
+
+int
+main ()
+{
+ S s;
+ s.s = 113;
+ #pragma omp parallel num_threads(4) default(firstprivate)
+ {
+ if (s.s != 113)
+ abort ();
+ s.s = omp_get_thread_num ();
+ #pragma omp barrier
+ if (s.s != omp_get_thread_num ())
+ abort ();
+ }
+ #pragma omp parallel num_threads(4) default(private)
+ {
+ if (s.s != 42)
+ abort ();
+ s.s = omp_get_thread_num () + 13;
+ #pragma omp barrier
+ if (s.s != omp_get_thread_num () + 13)
+ abort ();
+ }
+}
diff --git a/libgomp/testsuite/libgomp.c-c++-common/default-1.c b/libgomp/testsuite/libgomp.c-c++-common/default-1.c
new file mode 100644
index 00000000000..2a1d05ab0e3
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/default-1.c
@@ -0,0 +1,25 @@
+#include <omp.h>
+#include <stdlib.h>
+
+int
+main ()
+{
+ int v = 42;
+ #pragma omp parallel num_threads(4) default(firstprivate)
+ {
+ if (v != 42)
+ abort ();
+ v = omp_get_thread_num ();
+ #pragma omp barrier
+ if (v != omp_get_thread_num ())
+ abort ();
+ }
+ #pragma omp parallel num_threads(4) default(private)
+ {
+ v = omp_get_thread_num () + 13;
+ #pragma omp barrier
+ if (v != omp_get_thread_num () + 13)
+ abort ();
+ }
+ return 0;
+}
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2021-09-18 7:49 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-18 7:49 [gcc r12-3654] openmp: Allow private or firstprivate arguments to default clause even for C/C++ Jakub Jelinek
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).