Allow target attributes in non-gnu namespaces

Currently there are four static sources of attributes:

- LANG_HOOKS_ATTRIBUTE_TABLE
- LANG_HOOKS_COMMON_ATTRIBUTE_TABLE
- LANG_HOOKS_FORMAT_ATTRIBUTE_TABLE
- TARGET_ATTRIBUTE_TABLE

All of the attributes in these tables go in the "gnu" namespace.
This means that they can use the traditional GNU __attribute__((...))
syntax and the standard [[gnu::...]] syntax.

Standard attributes are registered dynamically with a null namespace.
There are no supported attributes in other namespaces (clang, vendor
namespaces, etc.).

This patch tries to generalise things by making the namespace
part of the attribute specification.

It's usual for multiple attributes to be defined in the same namespace,
so rather than adding the namespace to each individual definition,
it seemed better to group attributes in the same namespace together.
This would also allow us to reuse the same table for clang attributes
that are written with the GNU syntax, or other similar situations
where the attribute can be accessed via multiple "spellings".

The patch therefore adds a scoped_attribute_specs that contains
a namespace and a list of attributes in that namespace.

It's still possible to have multiple scoped_attribute_specs
for the same namespace.  E.g. it makes sense to keep the
C++-specific, C/C++-common, and format-related attributes in
separate tables, even though they're all GNU attributes.

Current lists of attributes are terminated by a null name.
Rather than keep that for the new structure, it seemed neater
to use an array_slice.  This also makes the tables slighly more
compact.

In general, a target might want to support attributes in multiple
namespaces.  Rather than have a separate hook for each possibility
(like the three langhooks above), it seemed better to make
TARGET_ATTRIBUTE_TABLE a table of tables.  Specifically, it's
an array_slice of scoped_attribute_specs.

We can do the same thing for langhooks, which allows the three hooks
above to be merged into a single LANG_HOOKS_ATTRIBUTE_TABLE.
It also allows the standard attributes to be registered statically
and checked by the usual attribs.cc checks.

The patch adds a TARGET_GNU_ATTRIBUTES helper for the common case
in which a target wants a single table of gnu attributes.  It can
only be used if the table is free of preprocessor directives.

There are probably other things we need to do to make vendor namespaces
work smoothly.  E.g. in principle it would be good to make exclusion
sets namespace-aware.  But to some extent we have that with standard
vs. gnu attributes too.  This patch is just supposed to be a first step.

gcc/
	* attribs.h (scoped_attribute_specs): New structure.
	(register_scoped_attributes): Take a reference to a
	scoped_attribute_specs instead of separate namespace and array
	parameters.
	* plugin.h (register_scoped_attributes): Likewise.
	* attribs.cc (register_scoped_attributes): Likewise.
	(attribute_tables): Change into an array of scoped_attribute_specs
	pointers.  Reduce to 1 element for frontends and 1 element for targets.
	(empty_attribute_table): Delete.
	(check_attribute_tables): Update for changes to attribute_tables.
	Use a hash_set to identify duplicates.
	(handle_ignored_attributes_option): Update for above changes.
	(init_attributes): Likewise.
	(excl_pair): Delete.
	(test_attribute_exclusions): Update for above changes.  Don't
	enforce symmetry for standard attributes in the top-level namespace.
	* langhooks-def.h (LANG_HOOKS_COMMON_ATTRIBUTE_TABLE): Delete.
	(LANG_HOOKS_FORMAT_ATTRIBUTE_TABLE): Likewise.
	(LANG_HOOKS_INITIALIZER): Update accordingly.
	(LANG_HOOKS_ATTRIBUTE_TABLE): Define to an empty constructor.
	* langhooks.h (lang_hooks::common_attribute_table): Delete.
	(lang_hooks::format_attribute_table): Likewise.
	(lang_hooks::attribute_table): Redefine to an array of
	scoped_attribute_specs pointers.
	* target-def.h (TARGET_GNU_ATTRIBUTES): New macro.
	* target.def (attribute_spec): Redefine to return an array of
	scoped_attribute_specs pointers.
	* tree-inline.cc (function_attribute_inlinable_p): Update accordingly.
	* doc/tm.texi: Regenerate.
	* config/aarch64/aarch64.cc (aarch64_attribute_table): Define using
	TARGET_GNU_ATTRIBUTES.
	* config/alpha/alpha.cc (vms_attribute_table): Likewise.
	* config/avr/avr.cc (avr_attribute_table): Likewise.
	* config/bfin/bfin.cc (bfin_attribute_table): Likewise.
	* config/bpf/bpf.cc (bpf_attribute_table): Likewise.
	* config/csky/csky.cc (csky_attribute_table): Likewise.
	* config/epiphany/epiphany.cc (epiphany_attribute_table): Likewise.
	* config/gcn/gcn.cc (gcn_attribute_table): Likewise.
	* config/h8300/h8300.cc (h8300_attribute_table): Likewise.
	* config/loongarch/loongarch.cc (loongarch_attribute_table): Likewise.
	* config/m32c/m32c.cc (m32c_attribute_table): Likewise.
	* config/m32r/m32r.cc (m32r_attribute_table): Likewise.
	* config/m68k/m68k.cc (m68k_attribute_table): Likewise.
	* config/mcore/mcore.cc (mcore_attribute_table): Likewise.
	* config/microblaze/microblaze.cc (microblaze_attribute_table):
	Likewise.
	* config/mips/mips.cc (mips_attribute_table): Likewise.
	* config/msp430/msp430.cc (msp430_attribute_table): Likewise.
	* config/nds32/nds32.cc (nds32_attribute_table): Likewise.
	* config/nvptx/nvptx.cc (nvptx_attribute_table): Likewise.
	* config/riscv/riscv.cc (riscv_attribute_table): Likewise.
	* config/rl78/rl78.cc (rl78_attribute_table): Likewise.
	* config/rx/rx.cc (rx_attribute_table): Likewise.
	* config/s390/s390.cc (s390_attribute_table): Likewise.
	* config/sh/sh.cc (sh_attribute_table): Likewise.
	* config/sparc/sparc.cc (sparc_attribute_table): Likewise.
	* config/stormy16/stormy16.cc (xstormy16_attribute_table): Likewise.
	* config/v850/v850.cc (v850_attribute_table): Likewise.
	* config/visium/visium.cc (visium_attribute_table): Likewise.
	* config/arc/arc.cc (arc_attribute_table): Likewise.  Move further
	down file.
	* config/arm/arm.cc (arm_attribute_table): Update for above changes,
	using...
	(arm_gnu_attributes, arm_gnu_attribute_table): ...these new globals.
	* config/i386/i386-options.h (ix86_attribute_table): Delete.
	(ix86_gnu_attribute_table): Declare.
	* config/i386/i386-options.cc (ix86_attribute_table): Replace with...
	(ix86_gnu_attributes, ix86_gnu_attribute_table): ...these two globals.
	* config/i386/i386.cc (ix86_attribute_table): Define as an array of
	scoped_attribute_specs pointers.
	* config/ia64/ia64.cc (ia64_attribute_table): Update for above changes,
	using...
	(ia64_gnu_attributes, ia64_gnu_attribute_table): ...these new globals.
	* config/rs6000/rs6000.cc (rs6000_attribute_table): Update for above
	changes, using...
	(rs6000_gnu_attributes, rs6000_gnu_attribute_table): ...these new
	globals.

gcc/ada/
	* gcc-interface/gigi.h (gnat_internal_attribute_table): Change
	type to scoped_attribute_specs.
	* gcc-interface/utils.cc (gnat_internal_attribute_table): Likewise,
	using...
	(gnat_internal_attributes): ...this as the underlying array.
	* gcc-interface/misc.cc (gnat_attribute_table): New global.
	(LANG_HOOKS_ATTRIBUTE_TABLE): Use it.

gcc/c-family/
	* c-common.h (c_common_attribute_table): Replace with...
	(c_common_gnu_attribute_table): ...this.
	(c_common_format_attribute_table): Change type to
	scoped_attribute_specs.
	* c-attribs.cc (c_common_attribute_table): Replace with...
	(c_common_gnu_attributes, c_common_gnu_attribute_table): ...these
	new globals.
	(c_common_format_attribute_table): Change type to
	scoped_attribute_specs, using...
	(c_common_format_attributes): ...this as the underlying array.

gcc/c/
	* c-tree.h (std_attribute_table): Declare.
	* c-decl.cc (std_attribute_table): Change type to
	scoped_attribute_specs, using...
	(std_attributes): ...this as the underlying array.
	(c_init_decl_processing): Remove call to register_scoped_attributes.
	* c-objc-common.h (c_objc_attribute_table): New global.
	(LANG_HOOKS_ATTRIBUTE_TABLE): Use it.
	(LANG_HOOKS_COMMON_ATTRIBUTE_TABLE): Delete.
	(LANG_HOOKS_FORMAT_ATTRIBUTE_TABLE): Delete.

gcc/cp/
	* cp-tree.h (cxx_attribute_table): Delete.
	(cxx_gnu_attribute_table, std_attribute_table): Declare.
	* cp-objcp-common.h (LANG_HOOKS_COMMON_ATTRIBUTE_TABLE): Delete.
	(LANG_HOOKS_FORMAT_ATTRIBUTE_TABLE): Delete.
	(cp_objcp_attribute_table): New table.
	(LANG_HOOKS_ATTRIBUTE_TABLE): Redefine.
	* tree.cc (cxx_attribute_table): Replace with...
	(cxx_gnu_attributes, cxx_gnu_attribute_table): ...these globals.
	(std_attribute_table): Change type to scoped_attribute_specs, using...
	(std_attributes): ...this as the underlying array.
	(init_tree): Remove call to register_scoped_attributes.

gcc/d/
	* d-tree.h (d_langhook_attribute_table): Replace with...
	(d_langhook_gnu_attribute_table): ...this.
	(d_langhook_common_attribute_table): Change type to
	scoped_attribute_specs.
	* d-attribs.cc (d_langhook_common_attribute_table): Change type to
	scoped_attribute_specs, using...
	(d_langhook_common_attributes): ...this as the underlying array.
	(d_langhook_attribute_table): Replace with...
	(d_langhook_gnu_attributes, d_langhook_gnu_attribute_table): ...these
	new globals.
	(uda_attribute_p): Update accordingly, and update for new
	targetm.attribute_table type.
	* d-lang.cc (d_langhook_attribute_table): New global.
	(LANG_HOOKS_COMMON_ATTRIBUTE_TABLE): Delete.

gcc/fortran/
	* f95-lang.cc: Include attribs.h.
	(gfc_attribute_table): Change to an array of scoped_attribute_specs
	pointers, using...
	(gfc_gnu_attributes, gfc_gnu_attribute_table): ...these new globals.

gcc/jit/
	* dummy-frontend.cc (jit_format_attribute_table): Change type to
	scoped_attribute_specs, using...
	(jit_format_attributes): ...this as the underlying array.
	(jit_attribute_table): Change to an array of scoped_attribute_specs
	pointers, using...
	(jit_gnu_attributes, jit_gnu_attribute_table): ...these new globals
	for the original array.  Include the format attributes.
	(LANG_HOOKS_COMMON_ATTRIBUTE_TABLE): Delete.
	(LANG_HOOKS_FORMAT_ATTRIBUTE_TABLE): Delete.
	(LANG_HOOKS_ATTRIBUTE_TABLE): Define.

gcc/lto/
	* lto-lang.cc (lto_format_attribute_table): Change type to
	scoped_attribute_specs, using...
	(lto_format_attributes): ...this as the underlying array.
	(lto_attribute_table): Change to an array of scoped_attribute_specs
	pointers, using...
	(lto_gnu_attributes, lto_gnu_attribute_table): ...these new globals
	for the original array.  Include the format attributes.
	(LANG_HOOKS_COMMON_ATTRIBUTE_TABLE): Delete.
	(LANG_HOOKS_FORMAT_ATTRIBUTE_TABLE): Delete.
	(LANG_HOOKS_ATTRIBUTE_TABLE): Define.

3 files changed, 26 insertions, 21 deletions

diff --git a/gcc/d/d-attribs.cc b/gcc/d/d-attribs.cc
index c0dc0e2..f641105 100644
--- a/gcc/d/d-attribs.cc
+++ b/gcc/d/d-attribs.cc
@@ -162,7 +162,7 @@ extern const struct attribute_spec::exclusions attr_cold_hot_exclusions[] =
 
 /* Table of machine-independent attributes.
    For internal use (marking of built-ins) only.  */
-const attribute_spec d_langhook_common_attribute_table[] =
+static const attribute_spec d_langhook_common_attributes[] =
 {
   ATTR_SPEC ("noreturn", 0, 0, true, false, false, false,
 	     handle_noreturn_attribute, attr_noreturn_exclusions),
@@ -190,11 +190,15 @@ const attribute_spec d_langhook_common_attribute_table[] =
 	     handle_fnspec_attribute, NULL),
   ATTR_SPEC ("omp declare simd", 0, -1, true,  false, false, false,
 	     handle_omp_declare_simd_attribute, NULL),
-  ATTR_SPEC (NULL, 0, 0, false, false, false, false, NULL, NULL),
+};
+
+const scoped_attribute_specs d_langhook_common_attribute_table =
+{
+  "gnu", d_langhook_common_attributes
 };
 
 /* Table of D language attributes exposed by `gcc.attribute' UDAs.  */
-const attribute_spec d_langhook_attribute_table[] =
+static const attribute_spec d_langhook_gnu_attributes[] =
 {
   ATTR_SPEC ("noinline", 0, 0, true, false, false, false,
 	     d_handle_noinline_attribute, attr_noinline_exclusions),
@@ -238,9 +242,12 @@ const attribute_spec d_langhook_attribute_table[] =
 	     d_handle_used_attribute, NULL),
   ATTR_SPEC ("visibility", 1, 1, false, false, false, false,
 	     d_handle_visibility_attribute, NULL),
-  ATTR_SPEC (NULL, 0, 0, false, false, false, false, NULL, NULL),
 };
 
+const scoped_attribute_specs d_langhook_gnu_attribute_table =
+{
+  "gnu", d_langhook_gnu_attributes
+};
 
 /* Insert the type attribute ATTRNAME with value VALUE into TYPE.
    Returns a new variant of the original type declaration.  */
@@ -283,20 +290,14 @@ uda_attribute_p (const char *name)
 
   /* Search both our language, and target attribute tables.
      Common and format attributes are kept internal.  */
-  for (const attribute_spec *p = d_langhook_attribute_table; p->name; p++)
-    {
-      if (get_identifier (p->name) == ident)
-	return true;
-    }
+  for (const attribute_spec &p : d_langhook_gnu_attributes)
+    if (get_identifier (p.name) == ident)
+      return true;
 
-  if (targetm.attribute_table)
-    {
-      for (const attribute_spec *p = targetm.attribute_table; p->name; p++)
-	{
-	  if (get_identifier (p->name) == ident)
-	    return true;
-	}
-    }
+  for (auto scoped_attributes : targetm.attribute_table)
+    for (const attribute_spec &p : scoped_attributes->attributes)
+      if (get_identifier (p.name) == ident)
+	return true;
 
   return false;
 }
diff --git a/gcc/d/d-lang.cc b/gcc/d/d-lang.cc
index 61fc160..dcbffec 100644
--- a/gcc/d/d-lang.cc
+++ b/gcc/d/d-lang.cc
@@ -1927,6 +1927,12 @@ d_get_sarif_source_language (const char *)
   return "d";
 }
 
+const scoped_attribute_specs *const d_langhook_attribute_table[] =
+{
+  &d_langhook_gnu_attribute_table,
+  &d_langhook_common_attribute_table,
+};
+
 /* Definitions for our language-specific hooks.  */
 
 #undef LANG_HOOKS_NAME
@@ -1938,7 +1944,6 @@ d_get_sarif_source_language (const char *)
 #undef LANG_HOOKS_HANDLE_OPTION
 #undef LANG_HOOKS_POST_OPTIONS
 #undef LANG_HOOKS_PARSE_FILE
-#undef LANG_HOOKS_COMMON_ATTRIBUTE_TABLE
 #undef LANG_HOOKS_ATTRIBUTE_TABLE
 #undef LANG_HOOKS_GET_ALIAS_SET
 #undef LANG_HOOKS_TYPES_COMPATIBLE_P
@@ -1971,7 +1976,6 @@ d_get_sarif_source_language (const char *)
 #define LANG_HOOKS_HANDLE_OPTION	    d_handle_option
 #define LANG_HOOKS_POST_OPTIONS		    d_post_options
 #define LANG_HOOKS_PARSE_FILE		    d_parse_file
-#define LANG_HOOKS_COMMON_ATTRIBUTE_TABLE   d_langhook_common_attribute_table
 #define LANG_HOOKS_ATTRIBUTE_TABLE	    d_langhook_attribute_table
 #define LANG_HOOKS_GET_ALIAS_SET	    d_get_alias_set
 #define LANG_HOOKS_TYPES_COMPATIBLE_P	    d_types_compatible_p
diff --git a/gcc/d/d-tree.h b/gcc/d/d-tree.h
index d19c3f5..46a2873 100644
--- a/gcc/d/d-tree.h
+++ b/gcc/d/d-tree.h
@@ -520,8 +520,8 @@ extern tree insert_decl_attribute (tree, const char *, tree = NULL_TREE);
 extern void apply_user_attributes (Dsymbol *, tree);
 
 /* In d-builtins.cc.  */
-extern const attribute_spec d_langhook_attribute_table[];
-extern const attribute_spec d_langhook_common_attribute_table[];
+extern const struct scoped_attribute_specs d_langhook_gnu_attribute_table;
+extern const struct scoped_attribute_specs d_langhook_common_attribute_table;
 extern Type *build_frontend_type (tree);
 
 extern tree d_builtin_function (tree);