On 09/19/2017 03:00 PM, Joseph Myers wrote:
On Tue, 19 Sep 2017, Martin Sebor wrote:
In general, the data structures where you need to ensure manually that if
attribute A is listed in EXCL for B, then attribute B is also listed in
EXCL for A, seem concerning. I'd expect either data structures that make
such asymmetry impossible, or a self-test that verifies that the tables in
use are in fact symmetric (unless there is some reason the symmetry is not
in fact required and symmetric diagnostics still result from asymmetric
tables - in which case the various combinations and orderings of
gnu_inline and noinline definitely need tests to show that the diagnostics
work).
If I understand correctly what you're concerned about then I don't
think there are any such cases in the updated version of the patch.
I don't see how you ensure that it's not possible to have such asymmetry.
My point wasn't so much "there was a bug in the previous patch version" as
"the choice of data structures for defining such exclusions is prone to
such bugs". Which can be addressed either by using different data
structures (e.g. listing incompatible pairs in a single array) or by a
self-test to verify symmetry so a compiler with asymmetry doesn't build.
Okay, that's a useful thing to add. It exposed a couple of missing
attribute exclusions that I had overlooked. Thanks for the suggestion!
Attached is an incremental diff with just these changes to make review
easier and an updated patch.
As an aside, there are a number of other possible logic errors in
the attribute specifications that could be detected by self-tests.
The one I ran into is misspelled attribute names. The added test
detects misspelled names in exclusions, but not in the main specs.
Martin
diff --git a/gcc/attribs.c b/gcc/attribs.c
index 3f9ae37..2f9a692 100644
--- a/gcc/attribs.c
+++ b/gcc/attribs.c
@@ -28,6 +28,8 @@ along with GCC; see the file COPYING3. If not see
#include "stor-layout.h"
#include "langhooks.h"
#include "plugin.h"
+#include "selftest.h"
+#include "hash-set.h"
/* Table of the tables of attributes (common, language, format, machine)
searched. */
@@ -1078,3 +1080,124 @@ is_function_default_version (const tree decl)
return (TREE_CODE (attr) == STRING_CST
&& strcmp (TREE_STRING_POINTER (attr), "default") == 0);
}
+
+#if CHECKING_P
+
+namespace selftest
+{
+
+/* Helper types to verify the consistency attribute exclusions. */
+
+typedef std::pair<const char *, const char *> excl_pair;
+
+struct excl_hash_traits: typed_noop_remove<excl_pair>
+{
+ typedef excl_pair value_type;
+ typedef value_type compare_type;
+
+ static hashval_t hash (const value_type &x)
+ {
+ hashval_t h1 = htab_hash_string (x.first);
+ hashval_t h2 = htab_hash_string (x.second);
+ return h1 ^ h2;
+ }
+
+ static bool equal (const value_type &x, const value_type &y)
+ {
+ return !strcmp (x.first, y.first) && !strcmp (x.second, y.second);
+ }
+
+ static void mark_deleted (value_type &x)
+ {
+ x = value_type (NULL, NULL);
+ }
+
+ static void mark_empty (value_type &x)
+ {
+ x = value_type ("", "");
+ }
+
+ static bool is_deleted (const value_type &x)
+ {
+ return !x.first && !x.second;
+ }
+
+ static bool is_empty (const value_type &x)
+ {
+ return !*x.first && !*x.second;
+ }
+};
+
+
+/* Self-test to verify that each attribute exclusion is symmetric,
+ meaning that if attribute A is encoded as incompatible with
+ attribute B then the opposite relationship is also encoded.
+ This test also detects most cases of misspelled attribute names
+ in exclusions. */
+
+static void
+test_attribute_exclusions ()
+{
+ /* Iterate over the array of attribute tables first (with TI0 as
+ the index) and over the array of attribute_spec in each table
+ (with SI0 as the index). */
+ const size_t ntables = ARRAY_SIZE (attribute_tables);
+
+ /* Set of pairs of mutually exclusive attributes. */
+ typedef hash_set<excl_pair, excl_hash_traits> exclusion_set;
+ exclusion_set excl_set;
+
+ for (size_t ti0 = 0; ti0 != ntables; ++ti0)
+ for (size_t s0 = 0; attribute_tables[ti0][s0].name; ++s0)
+ {
+ const attribute_spec::exclusions *excl
+ = attribute_tables[ti0][s0].exclude;
+
+ /* Skip each attribute that doesn't define exclusions. */
+ if (!excl)
+ continue;
+
+ const char *attr_name = attribute_tables[ti0][s0].name;
+
+ /* Iterate over the set of exclusions for every attribute
+ (with EI0 as the index) adding the exclusions defined
+ for each to the set. */
+ for (size_t ei0 = 0; excl[ei0].name; ++ei0)
+ {
+ const char *excl_name = excl[ei0].name;
+
+ if (!strcmp (attr_name, excl_name))
+ continue;
+
+ excl_set.add (excl_pair (attr_name, excl_name));
+ }
+ }
+
+ /* Traverse the set of mutually exclusive pairs of attributes
+ and verify that they are symmetric. */
+ for (exclusion_set::iterator it = excl_set.begin ();
+ it != excl_set.end ();
+ ++it)
+ {
+ if (!excl_set.contains (excl_pair ((*it).second, (*it).first)))
+ {
+ /* An exclusion for an attribute has been found that
+ doesn't have a corresponding exclusion in the opposite
+ direction. */
+ char desc[120];
+ sprintf (desc, "'%s' attribute exclusion '%s' must be symmetric",
+ (*it).first, (*it).second);
+ fail (SELFTEST_LOCATION, desc);
+ }
+ }
+}
+
+void
+attribute_c_tests ()
+{
+ test_attribute_exclusions ();
+}
+
+} /* namespace selftest */
+
+#endif /* CHECKING_P */
diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index 17d6993..f1adf64 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -189,7 +189,6 @@ static const struct attribute_spec::exclusions attr_noinline_exclusions[] =
static const struct attribute_spec::exclusions attr_noreturn_exclusions[] =
{
- ATTR_EXCL ("noreturn", true, true, true),
ATTR_EXCL ("alloc_align", true, true, true),
ATTR_EXCL ("alloc_size", true, true, true),
ATTR_EXCL ("const", true, true, true),
@@ -226,6 +225,9 @@ static const struct attribute_spec::exclusions attr_alloc_exclusions[] =
static const struct attribute_spec::exclusions attr_const_pure_exclusions[] =
{
ATTR_EXCL ("const", true, true, true),
+ ATTR_EXCL ("alloc_align", true, true, true),
+ ATTR_EXCL ("alloc_size", true, true, true),
+ ATTR_EXCL ("malloc", true, true, true),
ATTR_EXCL ("noreturn", true, true, true),
ATTR_EXCL ("pure", true, true, true),
ATTR_EXCL (NULL, false, false, false)
diff --git a/gcc/selftest-run-tests.c b/gcc/selftest-run-tests.c
index 30e476d..9af84a0 100644
--- a/gcc/selftest-run-tests.c
+++ b/gcc/selftest-run-tests.c
@@ -25,6 +25,8 @@ along with GCC; see the file COPYING3. If not see
#include "target.h"
#include "langhooks.h"
#include "options.h"
+#include "stringpool.h"
+#include "attribs.h"
/* This function needed to be split out from selftest.c as it references
tests from the whole source tree, and so is within
@@ -83,6 +85,7 @@ selftest::run_tests ()
spellcheck_c_tests ();
spellcheck_tree_c_tests ();
tree_cfg_c_tests ();
+ attribute_c_tests ();
/* This one relies on most of the above. */
function_tests_c_tests ();
diff --git a/gcc/selftest.h b/gcc/selftest.h
index 0572fef..608f4ee 100644
--- a/gcc/selftest.h
+++ b/gcc/selftest.h
@@ -170,6 +170,7 @@ extern const char *path_to_selftest_files;
/* Declarations for specific families of tests (by source file), in
alphabetical order. */
+extern void attribute_c_tests ();
extern void bitmap_c_tests ();
extern void diagnostic_c_tests ();
extern void diagnostic_show_locus_c_tests ();
PR c/81544 - attribute noreturn and warn_unused_result on the same function accepted
gcc/c/ChangeLog:
PR c/81544
* c-decl.c (c_decl_attributes): Look up existing declaration and
pass it to decl_attributes.
gcc/c-family/ChangeLog:
PR c/81544
* c-attribs.c (attr_aligned_exclusions): New array.
(attr_alloc_exclusions, attr_cold_hot_exclusions): Same.
(attr_common_exclusions, attr_const_pure_exclusions): Same.
(attr_gnu_inline_exclusions, attr_inline_exclusions): Same.
(attr_noreturn_exclusions, attr_returns_twice_exclusions): Same.
(attr_warn_unused_result_exclusions): Same.
(handle_hot_attribute, handle_cold_attribute): Simplify.
(handle_const_attribute): Warn on function returning void.
(handle_pure_attribute): Same.
* c-warn.c (diagnose_mismatched_attributes): Simplify.
gcc/ChangeLog:
PR c/81544
* attribs.c (empty_attribute_table): Initialize new member of
struct attribute_spec.
(decl_attributes): Add argument. Handle mutually exclusive
combinations of attributes.
* attribs.h (decl_attributes): Add default argument.
* selftest.h (attribute_c_tests): Declare.
* selftest-run-tests.c (selftest::run_tests): Call attribute_c_tests.
* tree-core.h (attribute_spec::exclusions, exclude): New type and
member.
* doc/extend.texi (Common Function Attributes): Update const and pure.
gcc/testsuite/ChangeLog:
PR c/81544
* c-c++-common/Wattributes-2.c: New test.
* c-c++-common/Wattributes.c: New test.
* c-c++-common/attributes-3.c: Adjust.
* gcc.dg/attr-noinline.c: Adjust.
* gcc.dg/pr44964.c: Same.
* gcc.dg/torture/pr42363.c: Same.
* gcc.dg/tree-ssa/ssa-ccp-2.c: Same.
diff --git a/gcc/attribs.c b/gcc/attribs.c
index 05fa8ef..2f9a692 100644
--- a/gcc/attribs.c
+++ b/gcc/attribs.c
@@ -28,6 +28,8 @@ along with GCC; see the file COPYING3. If not see
#include "stor-layout.h"
#include "langhooks.h"
#include "plugin.h"
+#include "selftest.h"
+#include "hash-set.h"
/* Table of the tables of attributes (common, language, format, machine)
searched. */
@@ -94,7 +96,7 @@ static bool attributes_initialized = false;
static const struct attribute_spec empty_attribute_table[] =
{
- { NULL, 0, 0, false, false, false, NULL, false }
+ { NULL, 0, 0, false, false, false, NULL, false, NULL }
};
/* Return base name of the attribute. Ie '__attr__' is turned into 'attr'.
@@ -343,6 +345,97 @@ get_attribute_namespace (const_tree attr)
return get_identifier ("gnu");
}
+/* Check LAST_DECL and NODE of the same symbol for attributes that are
+ recorded in SPEC to be mutually exclusive with ATTRNAME, diagnose
+ them, and return true if any have been found. NODE can be a DECL
+ or a TYPE. */
+
+static bool
+diag_attr_exclusions (tree last_decl, tree node, tree attrname,
+ const attribute_spec *spec)
+{
+ const attribute_spec::exclusions *excl = spec->exclude;
+
+ tree_code code = TREE_CODE (node);
+
+ if ((code == FUNCTION_DECL && !excl->function
+ && (!excl->type || !spec->affects_type_identity))
+ || (code == VAR_DECL && !excl->variable
+ && (!excl->type || !spec->affects_type_identity))
+ || (((code == TYPE_DECL || RECORD_OR_UNION_TYPE_P (node)) && !excl->type)))
+ return false;
+
+ /* True if an attribute that's mutually exclusive with ATTRNAME
+ has been found. */
+ bool found = false;
+
+ if (last_decl && last_decl != node && TREE_TYPE (last_decl) != node)
+ {
+ /* Check both the last DECL and its type for conflicts with
+ the attribute being added to the current decl or type. */
+ found |= diag_attr_exclusions (last_decl, last_decl, attrname, spec);
+ tree decl_type = TREE_TYPE (last_decl);
+ found |= diag_attr_exclusions (last_decl, decl_type, attrname, spec);
+ }
+
+ /* NODE is either the current DECL to which the attribute is being
+ applied or its TYPE. For the former, consider the attributes on
+ both the DECL and its type. */
+ tree attrs[2];
+
+ if (DECL_P (node))
+ {
+ attrs[0] = DECL_ATTRIBUTES (node);
+ attrs[1] = TYPE_ATTRIBUTES (TREE_TYPE (node));
+ }
+ else
+ {
+ attrs[0] = TYPE_ATTRIBUTES (node);
+ attrs[1] = NULL_TREE;
+ }
+
+ /* Iterate over the mutually exclusive attribute names and verify
+ that the symbol doesn't contain it. */
+ for (unsigned i = 0; i != sizeof attrs / sizeof *attrs; ++i)
+ {
+ if (!attrs[i])
+ continue;
+
+ for ( ; excl->name; ++excl)
+ {
+ /* Avoid checking the attribute against itself. */
+ if (is_attribute_p (excl->name, attrname))
+ continue;
+
+ if (!lookup_attribute (excl->name, attrs[i]))
+ continue;
+
+ found = true;
+
+ /* Print a note? */
+ bool note = last_decl != NULL_TREE;
+
+ if (TREE_CODE (node) == FUNCTION_DECL
+ && DECL_BUILT_IN (node))
+ note &= warning (OPT_Wattributes,
+ "ignoring attribute %qE in declaration of "
+ "a built-in function %qD because it conflicts "
+ "with attribute %qs",
+ attrname, node, excl->name);
+ else
+ note &= warning (OPT_Wattributes,
+ "ignoring attribute %qE because "
+ "it conflicts with attribute %qs",
+ attrname, excl->name);
+
+ if (note)
+ inform (DECL_SOURCE_LOCATION (last_decl),
+ "previous declaration here");
+ }
+ }
+
+ return found;
+}
/* Process the attributes listed in ATTRIBUTES and install them in *NODE,
which is either a DECL (including a TYPE_DECL) or a TYPE. If a DECL,
@@ -354,7 +447,8 @@ get_attribute_namespace (const_tree attr)
a decl attribute to the declaration rather than to its type). */
tree
-decl_attributes (tree *node, tree attributes, int flags)
+decl_attributes (tree *node, tree attributes, int flags,
+ tree last_decl /* = NULL_TREE */)
{
tree a;
tree returned_attrs = NULL_TREE;
@@ -433,6 +527,8 @@ decl_attributes (tree *node, tree attributes, int flags)
targetm.insert_attributes (*node, &attributes);
+ /* Note that attributes on the same declaration are not necessarily
+ in the same order as in the source. */
for (a = attributes; a; a = TREE_CHAIN (a))
{
tree ns = get_attribute_namespace (a);
@@ -441,7 +537,6 @@ decl_attributes (tree *node, tree attributes, int flags)
tree *anode = node;
const struct attribute_spec *spec =
lookup_scoped_attribute_spec (ns, name);
- bool no_add_attrs = 0;
int fn_ptr_quals = 0;
tree fn_ptr_tmp = NULL_TREE;
@@ -490,7 +585,8 @@ decl_attributes (tree *node, tree attributes, int flags)
| (int) ATTR_FLAG_ARRAY_NEXT))
{
/* Pass on this attribute to be tried again. */
- returned_attrs = tree_cons (name, args, returned_attrs);
+ tree attr = tree_cons (name, args, NULL_TREE);
+ returned_attrs = chainon (returned_attrs, attr);
continue;
}
else
@@ -535,7 +631,8 @@ decl_attributes (tree *node, tree attributes, int flags)
else if (flags & (int) ATTR_FLAG_FUNCTION_NEXT)
{
/* Pass on this attribute to be tried again. */
- returned_attrs = tree_cons (name, args, returned_attrs);
+ tree attr = tree_cons (name, args, NULL_TREE);
+ returned_attrs = chainon (returned_attrs, attr);
continue;
}
@@ -557,15 +654,56 @@ decl_attributes (tree *node, tree attributes, int flags)
continue;
}
+ bool no_add_attrs = false;
+
if (spec->handler != NULL)
{
int cxx11_flag =
cxx11_attribute_p (a) ? ATTR_FLAG_CXX11 : 0;
- returned_attrs = chainon ((*spec->handler) (anode, name, args,
- flags|cxx11_flag,
- &no_add_attrs),
- returned_attrs);
+ /* Pass in an array of the current declaration followed
+ by the last pushed/merged declaration if one exists.
+ If the handler changes CUR_AND_LAST_DECL[0] replace
+ *ANODE with its value. */
+ tree cur_and_last_decl[] = { *anode, last_decl };
+ tree ret = (spec->handler) (cur_and_last_decl, name, args,
+ flags|cxx11_flag, &no_add_attrs);
+
+ *anode = cur_and_last_decl[0];
+ if (ret == error_mark_node)
+ {
+ warning (OPT_Wattributes, "%qE attribute ignored", name);
+ no_add_attrs = true;
+ }
+ else
+ returned_attrs = chainon (ret, returned_attrs);
+ }
+
+ /* If the attribute was successfully handled on its own and is
+ about to be added check for exclusions with other attributes
+ on the current declation as well as the last declaration of
+ the same symbol already processed (if one exists). */
+ bool built_in = flags & ATTR_FLAG_BUILT_IN;
+ if (spec->exclude
+ && !no_add_attrs
+ && (flag_checking || !built_in))
+ {
+ /* Always check attributes on user-defined functions.
+ Check them on built-ins only when -fchecking is set.
+ Ignore __builtin_unreachable -- it's both const and
+ noreturn. */
+
+ if (!built_in
+ || !DECL_P (*anode)
+ || (DECL_FUNCTION_CODE (*anode) != BUILT_IN_UNREACHABLE
+ && (DECL_FUNCTION_CODE (*anode)
+ != BUILT_IN_UBSAN_HANDLE_BUILTIN_UNREACHABLE)))
+ {
+ bool no_add = diag_attr_exclusions (last_decl, *anode, name, spec);
+ if (!no_add && anode != node)
+ no_add = diag_attr_exclusions (last_decl, *node, name, spec);
+ no_add_attrs |= no_add;
+ }
}
/* Layout the decl in case anything changed. */
@@ -942,3 +1080,124 @@ is_function_default_version (const tree decl)
return (TREE_CODE (attr) == STRING_CST
&& strcmp (TREE_STRING_POINTER (attr), "default") == 0);
}
+
+#if CHECKING_P
+
+namespace selftest
+{
+
+/* Helper types to verify the consistency attribute exclusions. */
+
+typedef std::pair<const char *, const char *> excl_pair;
+
+struct excl_hash_traits: typed_noop_remove<excl_pair>
+{
+ typedef excl_pair value_type;
+ typedef value_type compare_type;
+
+ static hashval_t hash (const value_type &x)
+ {
+ hashval_t h1 = htab_hash_string (x.first);
+ hashval_t h2 = htab_hash_string (x.second);
+ return h1 ^ h2;
+ }
+
+ static bool equal (const value_type &x, const value_type &y)
+ {
+ return !strcmp (x.first, y.first) && !strcmp (x.second, y.second);
+ }
+
+ static void mark_deleted (value_type &x)
+ {
+ x = value_type (NULL, NULL);
+ }
+
+ static void mark_empty (value_type &x)
+ {
+ x = value_type ("", "");
+ }
+
+ static bool is_deleted (const value_type &x)
+ {
+ return !x.first && !x.second;
+ }
+
+ static bool is_empty (const value_type &x)
+ {
+ return !*x.first && !*x.second;
+ }
+};
+
+
+/* Self-test to verify that each attribute exclusion is symmetric,
+ meaning that if attribute A is encoded as incompatible with
+ attribute B then the opposite relationship is also encoded.
+ This test also detects most cases of misspelled attribute names
+ in exclusions. */
+
+static void
+test_attribute_exclusions ()
+{
+ /* Iterate over the array of attribute tables first (with TI0 as
+ the index) and over the array of attribute_spec in each table
+ (with SI0 as the index). */
+ const size_t ntables = ARRAY_SIZE (attribute_tables);
+
+ /* Set of pairs of mutually exclusive attributes. */
+ typedef hash_set<excl_pair, excl_hash_traits> exclusion_set;
+ exclusion_set excl_set;
+
+ for (size_t ti0 = 0; ti0 != ntables; ++ti0)
+ for (size_t s0 = 0; attribute_tables[ti0][s0].name; ++s0)
+ {
+ const attribute_spec::exclusions *excl
+ = attribute_tables[ti0][s0].exclude;
+
+ /* Skip each attribute that doesn't define exclusions. */
+ if (!excl)
+ continue;
+
+ const char *attr_name = attribute_tables[ti0][s0].name;
+
+ /* Iterate over the set of exclusions for every attribute
+ (with EI0 as the index) adding the exclusions defined
+ for each to the set. */
+ for (size_t ei0 = 0; excl[ei0].name; ++ei0)
+ {
+ const char *excl_name = excl[ei0].name;
+
+ if (!strcmp (attr_name, excl_name))
+ continue;
+
+ excl_set.add (excl_pair (attr_name, excl_name));
+ }
+ }
+
+ /* Traverse the set of mutually exclusive pairs of attributes
+ and verify that they are symmetric. */
+ for (exclusion_set::iterator it = excl_set.begin ();
+ it != excl_set.end ();
+ ++it)
+ {
+ if (!excl_set.contains (excl_pair ((*it).second, (*it).first)))
+ {
+ /* An exclusion for an attribute has been found that
+ doesn't have a corresponding exclusion in the opposite
+ direction. */
+ char desc[120];
+ sprintf (desc, "'%s' attribute exclusion '%s' must be symmetric",
+ (*it).first, (*it).second);
+ fail (SELFTEST_LOCATION, desc);
+ }
+ }
+}
+
+void
+attribute_c_tests ()
+{
+ test_attribute_exclusions ();
+}
+
+} /* namespace selftest */
+
+#endif /* CHECKING_P */
diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index 0d9ab2d..3c0e148 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -146,6 +146,93 @@ static tree handle_fallthrough_attribute (tree *, tree, tree, int, bool *);
static tree handle_patchable_function_entry_attribute (tree *, tree, tree,
int, bool *);
+/* Helper to define attribute exclusions. */
+#define ATTR_EXCL(name, function, type, variable) \
+ { name, function, type, variable }
+
+/* Define attributes that are mutually exclusive with one another. */
+static const struct attribute_spec::exclusions attr_aligned_exclusions[] =
+{
+ /* Attribute name exclusion applies to:
+ function, type, variable */
+ ATTR_EXCL ("aligned", true, false, false),
+ ATTR_EXCL ("packed", true, false, false),
+ ATTR_EXCL (NULL, false, false, false)
+};
+
+static const struct attribute_spec::exclusions attr_cold_hot_exclusions[] =
+{
+ ATTR_EXCL ("cold", true, true, true),
+ ATTR_EXCL ("hot", true, true, true),
+ ATTR_EXCL (NULL, false, false, false)
+};
+
+static const struct attribute_spec::exclusions attr_common_exclusions[] =
+{
+ ATTR_EXCL ("common", true, true, true),
+ ATTR_EXCL ("nocommon", true, true, true),
+ ATTR_EXCL (NULL, false, false, false),
+};
+
+static const struct attribute_spec::exclusions attr_inline_exclusions[] =
+{
+ ATTR_EXCL ("noinline", true, true, true),
+ ATTR_EXCL (NULL, false, false, false),
+};
+
+static const struct attribute_spec::exclusions attr_noinline_exclusions[] =
+{
+ ATTR_EXCL ("always_inline", true, true, true),
+ ATTR_EXCL ("gnu_inline", true, true, true),
+ ATTR_EXCL (NULL, false, false, false),
+};
+
+static const struct attribute_spec::exclusions attr_noreturn_exclusions[] =
+{
+ ATTR_EXCL ("alloc_align", true, true, true),
+ ATTR_EXCL ("alloc_size", true, true, true),
+ ATTR_EXCL ("const", true, true, true),
+ ATTR_EXCL ("malloc", true, true, true),
+ ATTR_EXCL ("pure", true, true, true),
+ ATTR_EXCL ("returns_twice", true, true, true),
+ ATTR_EXCL ("warn_unused_result", true, true, true),
+ ATTR_EXCL (NULL, false, false, false),
+};
+
+static const struct attribute_spec::exclusions
+attr_warn_unused_result_exclusions[] =
+{
+ ATTR_EXCL ("noreturn", true, true, true),
+ ATTR_EXCL ("warn_unused_result", true, true, true),
+ ATTR_EXCL (NULL, false, false, false),
+};
+
+static const struct attribute_spec::exclusions attr_returns_twice_exclusions[] =
+{
+ ATTR_EXCL ("noreturn", true, true, true),
+ ATTR_EXCL (NULL, false, false, false),
+};
+
+/* Exclusions that apply to attribute alloc_align, alloc_size, and malloc. */
+static const struct attribute_spec::exclusions attr_alloc_exclusions[] =
+{
+ ATTR_EXCL ("const", true, true, true),
+ ATTR_EXCL ("noreturn", true, true, true),
+ ATTR_EXCL ("pure", true, true, true),
+ ATTR_EXCL (NULL, false, false, false),
+};
+
+static const struct attribute_spec::exclusions attr_const_pure_exclusions[] =
+{
+ ATTR_EXCL ("const", true, true, true),
+ ATTR_EXCL ("alloc_align", true, true, true),
+ ATTR_EXCL ("alloc_size", true, true, true),
+ ATTR_EXCL ("malloc", true, true, true),
+ ATTR_EXCL ("noreturn", true, true, true),
+ ATTR_EXCL ("pure", true, true, true),
+ ATTR_EXCL (NULL, false, false, false)
+};
+
/* Table of machine-independent attributes common to all C-like languages.
All attributes referencing arguments should be additionally processed
@@ -157,209 +244,230 @@ const struct attribute_spec c_common_attribute_table[] =
/* { name, min_len, max_len, decl_req, type_req, fn_type_req, handler,
affects_type_identity } */
{ "packed", 0, 0, false, false, false,
- handle_packed_attribute , false},
+ handle_packed_attribute , false,
+ attr_aligned_exclusions },
{ "nocommon", 0, 0, true, false, false,
- handle_nocommon_attribute, false},
+ handle_nocommon_attribute, false,
+ attr_common_exclusions },
{ "common", 0, 0, true, false, false,
- handle_common_attribute, false },
+ handle_common_attribute, false,
+ attr_common_exclusions },
/* FIXME: logically, noreturn attributes should be listed as
"false, true, true" and apply to function types. But implementing this
would require all the places in the compiler that use TREE_THIS_VOLATILE
on a decl to identify non-returning functions to be located and fixed
to check the function type instead. */
{ "noreturn", 0, 0, true, false, false,
- handle_noreturn_attribute, false },
+ handle_noreturn_attribute, false,
+ attr_noreturn_exclusions },
{ "volatile", 0, 0, true, false, false,
- handle_noreturn_attribute, false },
+ handle_noreturn_attribute, false, NULL },
{ "stack_protect", 0, 0, true, false, false,
- handle_stack_protect_attribute, false },
+ handle_stack_protect_attribute, false, NULL },
{ "noinline", 0, 0, true, false, false,
- handle_noinline_attribute, false },
+ handle_noinline_attribute, false,
+ attr_noinline_exclusions },
{ "noclone", 0, 0, true, false, false,
- handle_noclone_attribute, false },
+ handle_noclone_attribute, false, NULL },
{ "no_icf", 0, 0, true, false, false,
- handle_noicf_attribute, false },
+ handle_noicf_attribute, false, NULL },
{ "noipa", 0, 0, true, false, false,
- handle_noipa_attribute, false },
+ handle_noipa_attribute, false, NULL },
{ "leaf", 0, 0, true, false, false,
- handle_leaf_attribute, false },
+ handle_leaf_attribute, false, NULL },
{ "always_inline", 0, 0, true, false, false,
- handle_always_inline_attribute, false },
+ handle_always_inline_attribute, false,
+ attr_inline_exclusions },
{ "gnu_inline", 0, 0, true, false, false,
- handle_gnu_inline_attribute, false },
+ handle_gnu_inline_attribute, false,
+ attr_inline_exclusions },
{ "artificial", 0, 0, true, false, false,
- handle_artificial_attribute, false },
+ handle_artificial_attribute, false, NULL },
{ "flatten", 0, 0, true, false, false,
- handle_flatten_attribute, false },
+ handle_flatten_attribute, false, NULL },
{ "used", 0, 0, true, false, false,
- handle_used_attribute, false },
+ handle_used_attribute, false, NULL },
{ "unused", 0, 0, false, false, false,
- handle_unused_attribute, false },
+ handle_unused_attribute, false, NULL },
{ "externally_visible", 0, 0, true, false, false,
- handle_externally_visible_attribute, false },
+ handle_externally_visible_attribute, false,
+ NULL },
{ "no_reorder", 0, 0, true, false, false,
- handle_no_reorder_attribute, false },
+ handle_no_reorder_attribute, false, NULL },
/* The same comments as for noreturn attributes apply to const ones. */
{ "const", 0, 0, true, false, false,
- handle_const_attribute, false },
+ handle_const_attribute, false,
+ attr_const_pure_exclusions },
{ "scalar_storage_order", 1, 1, false, false, false,
- handle_scalar_storage_order_attribute, false },
+ handle_scalar_storage_order_attribute, false,
+ NULL },
{ "transparent_union", 0, 0, false, false, false,
- handle_transparent_union_attribute, false },
+ handle_transparent_union_attribute, false, NULL },
{ "constructor", 0, 1, true, false, false,
- handle_constructor_attribute, false },
+ handle_constructor_attribute, false, NULL },
{ "destructor", 0, 1, true, false, false,
- handle_destructor_attribute, false },
+ handle_destructor_attribute, false, NULL },
{ "mode", 1, 1, false, true, false,
- handle_mode_attribute, false },
+ handle_mode_attribute, false, NULL },
{ "section", 1, 1, true, false, false,
- handle_section_attribute, false },
+ handle_section_attribute, false, NULL },
{ "aligned", 0, 1, false, false, false,
- handle_aligned_attribute, false },
+ handle_aligned_attribute, false,
+ attr_aligned_exclusions },
{ "weak", 0, 0, true, false, false,
- handle_weak_attribute, false },
+ handle_weak_attribute, false, NULL },
{ "noplt", 0, 0, true, false, false,
- handle_noplt_attribute, false },
+ handle_noplt_attribute, false, NULL },
{ "ifunc", 1, 1, true, false, false,
- handle_ifunc_attribute, false },
+ handle_ifunc_attribute, false, NULL },
{ "alias", 1, 1, true, false, false,
- handle_alias_attribute, false },
+ handle_alias_attribute, false, NULL },
{ "weakref", 0, 1, true, false, false,
- handle_weakref_attribute, false },
+ handle_weakref_attribute, false, NULL },
{ "no_instrument_function", 0, 0, true, false, false,
handle_no_instrument_function_attribute,
- false },
+ false, NULL },
{ "no_profile_instrument_function", 0, 0, true, false, false,
handle_no_profile_instrument_function_attribute,
- false },
+ false, NULL },
{ "malloc", 0, 0, true, false, false,
- handle_malloc_attribute, false },
+ handle_malloc_attribute, false,
+ attr_alloc_exclusions },
{ "returns_twice", 0, 0, true, false, false,
- handle_returns_twice_attribute, false },
+ handle_returns_twice_attribute, false,
+ attr_returns_twice_exclusions },
{ "no_stack_limit", 0, 0, true, false, false,
- handle_no_limit_stack_attribute, false },
+ handle_no_limit_stack_attribute, false, NULL },
{ "pure", 0, 0, true, false, false,
- handle_pure_attribute, false },
+ handle_pure_attribute, false,
+ attr_const_pure_exclusions },
{ "transaction_callable", 0, 0, false, true, false,
- handle_tm_attribute, false },
+ handle_tm_attribute, false, NULL },
{ "transaction_unsafe", 0, 0, false, true, false,
- handle_tm_attribute, true },
+ handle_tm_attribute, true, NULL },
{ "transaction_safe", 0, 0, false, true, false,
- handle_tm_attribute, true },
+ handle_tm_attribute, true, NULL },
{ "transaction_safe_dynamic", 0, 0, true, false, false,
- handle_tm_attribute, false },
+ handle_tm_attribute, false, NULL },
{ "transaction_may_cancel_outer", 0, 0, false, true, false,
- handle_tm_attribute, false },
+ handle_tm_attribute, false, NULL },
/* ??? These two attributes didn't make the transition from the
Intel language document to the multi-vendor language document. */
{ "transaction_pure", 0, 0, false, true, false,
- handle_tm_attribute, false },
+ handle_tm_attribute, false, NULL },
{ "transaction_wrap", 1, 1, true, false, false,
- handle_tm_wrap_attribute, false },
+ handle_tm_wrap_attribute, false, NULL },
/* For internal use (marking of builtins) only. The name contains space
to prevent its usage in source code. */
{ "no vops", 0, 0, true, false, false,
- handle_novops_attribute, false },
+ handle_novops_attribute, false, NULL },
{ "deprecated", 0, 1, false, false, false,
- handle_deprecated_attribute, false },
+ handle_deprecated_attribute, false, NULL },
{ "vector_size", 1, 1, false, true, false,
- handle_vector_size_attribute, true },
+ handle_vector_size_attribute, true, NULL },
{ "visibility", 1, 1, false, false, false,
- handle_visibility_attribute, false },
+ handle_visibility_attribute, false, NULL },
{ "tls_model", 1, 1, true, false, false,
- handle_tls_model_attribute, false },
+ handle_tls_model_attribute, false, NULL },
{ "nonnull", 0, -1, false, true, true,
- handle_nonnull_attribute, false },
+ handle_nonnull_attribute, false, NULL },
{ "nothrow", 0, 0, true, false, false,
- handle_nothrow_attribute, false },
- { "may_alias", 0, 0, false, true, false, NULL, false },
+ handle_nothrow_attribute, false, NULL },
+ { "may_alias", 0, 0, false, true, false, NULL, false, NULL },
{ "cleanup", 1, 1, true, false, false,
- handle_cleanup_attribute, false },
+ handle_cleanup_attribute, false, NULL },
{ "warn_unused_result", 0, 0, false, true, true,
- handle_warn_unused_result_attribute, false },
+ handle_warn_unused_result_attribute, false,
+ attr_warn_unused_result_exclusions },
{ "sentinel", 0, 1, false, true, true,
- handle_sentinel_attribute, false },
+ handle_sentinel_attribute, false, NULL },
/* For internal use (marking of builtins) only. The name contains space
to prevent its usage in source code. */
{ "type generic", 0, 0, false, true, true,
- handle_type_generic_attribute, false },
+ handle_type_generic_attribute, false, NULL },
{ "alloc_size", 1, 2, false, true, true,
- handle_alloc_size_attribute, false },
+ handle_alloc_size_attribute, false,
+ attr_alloc_exclusions },
{ "cold", 0, 0, true, false, false,
- handle_cold_attribute, false },
+ handle_cold_attribute, false,
+ attr_cold_hot_exclusions },
{ "hot", 0, 0, true, false, false,
- handle_hot_attribute, false },
+ handle_hot_attribute, false,
+ attr_cold_hot_exclusions },
{ "no_address_safety_analysis",
0, 0, true, false, false,
handle_no_address_safety_analysis_attribute,
- false },
+ false, NULL },
{ "no_sanitize", 1, 1, true, false, false,
handle_no_sanitize_attribute,
- false },
+ false, NULL },
{ "no_sanitize_address", 0, 0, true, false, false,
handle_no_sanitize_address_attribute,
- false },
+ false, NULL },
{ "no_sanitize_thread", 0, 0, true, false, false,
handle_no_sanitize_thread_attribute,
- false },
+ false, NULL },
{ "no_sanitize_undefined", 0, 0, true, false, false,
handle_no_sanitize_undefined_attribute,
- false },
+ false, NULL },
{ "asan odr indicator", 0, 0, true, false, false,
handle_asan_odr_indicator_attribute,
- false },
+ false, NULL },
{ "warning", 1, 1, true, false, false,
- handle_error_attribute, false },
+ handle_error_attribute, false, NULL },
{ "error", 1, 1, true, false, false,
- handle_error_attribute, false },
+ handle_error_attribute, false, NULL },
{ "target", 1, -1, true, false, false,
- handle_target_attribute, false },
+ handle_target_attribute, false, NULL },
{ "target_clones", 1, -1, true, false, false,
- handle_target_clones_attribute, false },
+ handle_target_clones_attribute, false, NULL },
{ "optimize", 1, -1, true, false, false,
- handle_optimize_attribute, false },
+ handle_optimize_attribute, false, NULL },
/* For internal use only. The leading '*' both prevents its usage in
source code and signals that it may be overridden by machine tables. */
{ "*tm regparm", 0, 0, false, true, true,
- ignore_attribute, false },
+ ignore_attribute, false, NULL },
{ "no_split_stack", 0, 0, true, false, false,
- handle_no_split_stack_attribute, false },
+ handle_no_split_stack_attribute, false, NULL },
/* For internal use (marking of builtins and runtime functions) only.
The name contains space to prevent its usage in source code. */
{ "fn spec", 1, 1, false, true, true,
- handle_fnspec_attribute, false },
+ handle_fnspec_attribute, false, NULL },
{ "warn_unused", 0, 0, false, false, false,
- handle_warn_unused_attribute, false },
+ handle_warn_unused_attribute, false, NULL },
{ "returns_nonnull", 0, 0, false, true, true,
- handle_returns_nonnull_attribute, false },
+ handle_returns_nonnull_attribute, false, NULL },
{ "omp declare simd", 0, -1, true, false, false,
- handle_omp_declare_simd_attribute, false },
+ handle_omp_declare_simd_attribute, false, NULL },
{ "cilk simd function", 0, -1, true, false, false,
- handle_omp_declare_simd_attribute, false },
+ handle_omp_declare_simd_attribute, false, NULL },
{ "simd", 0, 1, true, false, false,
- handle_simd_attribute, false },
+ handle_simd_attribute, false, NULL },
{ "omp declare target", 0, 0, true, false, false,
- handle_omp_declare_target_attribute, false },
+ handle_omp_declare_target_attribute, false,
+ NULL },
{ "omp declare target link", 0, 0, true, false, false,
- handle_omp_declare_target_attribute, false },
+ handle_omp_declare_target_attribute, false,
+ NULL },
{ "alloc_align", 1, 1, false, true, true,
- handle_alloc_align_attribute, false },
+ handle_alloc_align_attribute, false,
+ attr_alloc_exclusions },
{ "assume_aligned", 1, 2, false, true, true,
- handle_assume_aligned_attribute, false },
+ handle_assume_aligned_attribute, false, NULL },
{ "designated_init", 0, 0, false, true, false,
- handle_designated_init_attribute, false },
+ handle_designated_init_attribute, false, NULL },
{ "bnd_variable_size", 0, 0, true, false, false,
- handle_bnd_variable_size_attribute, false },
+ handle_bnd_variable_size_attribute, false, NULL },
{ "bnd_legacy", 0, 0, true, false, false,
- handle_bnd_legacy, false },
+ handle_bnd_legacy, false, NULL },
{ "bnd_instrument", 0, 0, true, false, false,
- handle_bnd_instrument, false },
+ handle_bnd_instrument, false, NULL },
{ "fallthrough", 0, 0, false, false, false,
- handle_fallthrough_attribute, false },
+ handle_fallthrough_attribute, false, NULL },
{ "patchable_function_entry", 1, 2, true, false, false,
handle_patchable_function_entry_attribute,
- false },
- { NULL, 0, 0, false, false, false, NULL, false }
+ false, NULL },
+ { NULL, 0, 0, false, false, false, NULL, false, NULL }
};
/* Give the specifications for the format attributes, used by C and all
@@ -374,10 +482,10 @@ const struct attribute_spec c_common_format_attribute_table[] =
/* { name, min_len, max_len, decl_req, type_req, fn_type_req, handler,
affects_type_identity } */
{ "format", 3, 3, false, true, true,
- handle_format_attribute, false },
+ handle_format_attribute, false, NULL },
{ "format_arg", 1, 1, false, true, true,
- handle_format_arg_attribute, false },
- { NULL, 0, 0, false, false, false, NULL, false }
+ handle_format_arg_attribute, false, NULL },
+ { NULL, 0, 0, false, false, false, NULL, false, NULL }
};
/* Returns TRUE iff the attribute indicated by ATTR_ID takes a plain
@@ -515,14 +623,7 @@ handle_hot_attribute (tree *node, tree name, tree ARG_UNUSED (args),
if (TREE_CODE (*node) == FUNCTION_DECL
|| TREE_CODE (*node) == LABEL_DECL)
{
- if (lookup_attribute ("cold", DECL_ATTRIBUTES (*node)) != NULL)
- {
- warning (OPT_Wattributes, "%qE attribute ignored due to conflict "
- "with attribute %qs", name, "cold");
- *no_add_attrs = true;
- }
- /* Most of the rest of the hot processing is done later with
- lookup_attribute. */
+ /* Attribute hot processing is done later with lookup_attribute. */
}
else
{
@@ -543,14 +644,7 @@ handle_cold_attribute (tree *node, tree name, tree ARG_UNUSED (args),
if (TREE_CODE (*node) == FUNCTION_DECL
|| TREE_CODE (*node) == LABEL_DECL)
{
- if (lookup_attribute ("hot", DECL_ATTRIBUTES (*node)) != NULL)
- {
- warning (OPT_Wattributes, "%qE attribute ignored due to conflict "
- "with attribute %qs", name, "hot");
- *no_add_attrs = true;
- }
- /* Most of the rest of the cold processing is done later with
- lookup_attribute. */
+ /* Attribute cold processing is done later with lookup_attribute. */
}
else
{
@@ -1064,7 +1158,7 @@ handle_no_reorder_attribute (tree *pnode,
static tree
handle_const_attribute (tree *node, tree name, tree ARG_UNUSED (args),
- int ARG_UNUSED (flags), bool *no_add_attrs)
+ int flags, bool *no_add_attrs)
{
tree type = TREE_TYPE (*node);
@@ -1085,6 +1179,14 @@ handle_const_attribute (tree *node, tree name, tree ARG_UNUSED (args),
*no_add_attrs = true;
}
+ /* void __builtin_unreachable(void) is const. Accept other such
+ built-ins but warn on user-defined functions that return void. */
+ if (!(flags & ATTR_FLAG_BUILT_IN)
+ && TREE_CODE (*node) == FUNCTION_DECL
+ && VOID_TYPE_P (TREE_TYPE (type)))
+ warning (OPT_Wattributes, "%qE attribute on function "
+ "returning %<void%>", name);
+
return NULL_TREE;
}
@@ -1667,14 +1769,18 @@ check_cxx_fundamental_alignment_constraints (tree node,
struct attribute_spec.handler. */
static tree
-handle_aligned_attribute (tree *node, tree ARG_UNUSED (name), tree args,
+handle_aligned_attribute (tree *node, tree name, tree args,
int flags, bool *no_add_attrs)
{
tree decl = NULL_TREE;
tree *type = NULL;
- int is_type = 0;
+ bool is_type = false;
tree align_expr;
- int i;
+
+ /* The last (already pushed) declaration with all validated attributes
+ merged in or the current about-to-be-pushed one if one hasn't been
+ yet. */
+ tree last_decl = node[1] ? node[1] : *node;
if (args)
{
@@ -1693,10 +1799,21 @@ handle_aligned_attribute (tree *node, tree ARG_UNUSED (name), tree args,
is_type = TREE_CODE (*node) == TYPE_DECL;
}
else if (TYPE_P (*node))
- type = node, is_type = 1;
+ type = node, is_type = true;
+
+ /* Log2 of specified alignment. */
+ int pow2align = check_user_alignment (align_expr, true);
+
+ /* The alignment in bits corresponding to the specified alignment. */
+ unsigned bitalign = (1U << pow2align) * BITS_PER_UNIT;
+
+ /* The alignment of the current declaration and that of the last
+ pushed declaration, determined on demand below. */
+ unsigned curalign = 0;
+ unsigned lastalign = 0;
- if ((i = check_user_alignment (align_expr, true)) == -1
- || !check_cxx_fundamental_alignment_constraints (*node, i, flags))
+ if (pow2align == -1
+ || !check_cxx_fundamental_alignment_constraints (*node, pow2align, flags))
*no_add_attrs = true;
else if (is_type)
{
@@ -1717,7 +1834,7 @@ handle_aligned_attribute (tree *node, tree ARG_UNUSED (name), tree args,
else
*type = build_variant_type_copy (*type);
- SET_TYPE_ALIGN (*type, (1U << i) * BITS_PER_UNIT);
+ SET_TYPE_ALIGN (*type, bitalign);
TYPE_USER_ALIGN (*type) = 1;
}
else if (! VAR_OR_FUNCTION_DECL_P (decl)
@@ -1726,8 +1843,34 @@ handle_aligned_attribute (tree *node, tree ARG_UNUSED (name), tree args,
error ("alignment may not be specified for %q+D", decl);
*no_add_attrs = true;
}
+ else if (TREE_CODE (decl) == FUNCTION_DECL
+ && ((curalign = DECL_ALIGN (decl)) > bitalign
+ || ((lastalign = DECL_ALIGN (last_decl)) > bitalign)))
+ {
+ /* Either a prior attribute on the same declaration or one
+ on a prior declaration of the same function specifies
+ stricter alignment than this attribute. */
+ bool note = lastalign != 0;
+ if (lastalign)
+ curalign = lastalign;
+
+ curalign /= BITS_PER_UNIT;
+ bitalign /= BITS_PER_UNIT;
+
+ if (DECL_USER_ALIGN (decl) || DECL_USER_ALIGN (last_decl))
+ warning (OPT_Wattributes,
+ "ignoring attribute %<%E (%u)%> because it conflicts with "
+ "attribute %<%E (%u)%>", name, bitalign, name, curalign);
+ else
+ error ("alignment for %q+D must be at least %d", decl, curalign);
+
+ if (note)
+ inform (DECL_SOURCE_LOCATION (last_decl), "previous declaration here");
+
+ *no_add_attrs = true;
+ }
else if (DECL_USER_ALIGN (decl)
- && DECL_ALIGN (decl) > (1U << i) * BITS_PER_UNIT)
+ && DECL_ALIGN (decl) > bitalign)
/* C++-11 [dcl.align/4]:
When multiple alignment-specifiers are specified for an
@@ -1737,21 +1880,9 @@ handle_aligned_attribute (tree *node, tree ARG_UNUSED (name), tree args,
This formally comes from the c++11 specification but we are
doing it for the GNU attribute syntax as well. */
*no_add_attrs = true;
- else if (TREE_CODE (decl) == FUNCTION_DECL
- && DECL_ALIGN (decl) > (1U << i) * BITS_PER_UNIT)
- {
- if (DECL_USER_ALIGN (decl))
- error ("alignment for %q+D was previously specified as %d "
- "and may not be decreased", decl,
- DECL_ALIGN (decl) / BITS_PER_UNIT);
- else
- error ("alignment for %q+D must be at least %d", decl,
- DECL_ALIGN (decl) / BITS_PER_UNIT);
- *no_add_attrs = true;
- }
else
{
- SET_DECL_ALIGN (decl, (1U << i) * BITS_PER_UNIT);
+ SET_DECL_ALIGN (decl, bitalign);
DECL_USER_ALIGN (decl) = 1;
}
@@ -2476,8 +2607,15 @@ handle_pure_attribute (tree *node, tree name, tree ARG_UNUSED (args),
int ARG_UNUSED (flags), bool *no_add_attrs)
{
if (TREE_CODE (*node) == FUNCTION_DECL)
- DECL_PURE_P (*node) = 1;
- /* ??? TODO: Support types. */
+ {
+ tree type = TREE_TYPE (*node);
+ if (VOID_TYPE_P (TREE_TYPE (type)))
+ warning (OPT_Wattributes, "%qE attribute on function "
+ "returning %<void%>", name);
+
+ DECL_PURE_P (*node) = 1;
+ /* ??? TODO: Support types. */
+ }
else
{
warning (OPT_Wattributes, "%qE attribute ignored", name);
diff --git a/gcc/c-family/c-warn.c b/gcc/c-family/c-warn.c
index e970ab2..f7c8eac 100644
--- a/gcc/c-family/c-warn.c
+++ b/gcc/c-family/c-warn.c
@@ -2143,36 +2143,19 @@ diagnose_mismatched_attributes (tree olddecl, tree newdecl)
newdecl);
/* Diagnose inline __attribute__ ((noinline)) which is silly. */
+ const char *noinline = "noinline";
+
if (DECL_DECLARED_INLINE_P (newdecl)
&& DECL_UNINLINABLE (olddecl)
- && lookup_attribute ("noinline", DECL_ATTRIBUTES (olddecl)))
+ && lookup_attribute (noinline, DECL_ATTRIBUTES (olddecl)))
warned |= warning (OPT_Wattributes, "inline declaration of %qD follows "
- "declaration with attribute noinline", newdecl);
+ "declaration with attribute %qs", newdecl, noinline);
else if (DECL_DECLARED_INLINE_P (olddecl)
&& DECL_UNINLINABLE (newdecl)
&& lookup_attribute ("noinline", DECL_ATTRIBUTES (newdecl)))
warned |= warning (OPT_Wattributes, "declaration of %q+D with attribute "
- "noinline follows inline declaration ", newdecl);
- else if (lookup_attribute ("noinline", DECL_ATTRIBUTES (newdecl))
- && lookup_attribute ("always_inline", DECL_ATTRIBUTES (olddecl)))
- warned |= warning (OPT_Wattributes, "declaration of %q+D with attribute "
- "%qs follows declaration with attribute %qs",
- newdecl, "noinline", "always_inline");
- else if (lookup_attribute ("always_inline", DECL_ATTRIBUTES (newdecl))
- && lookup_attribute ("noinline", DECL_ATTRIBUTES (olddecl)))
- warned |= warning (OPT_Wattributes, "declaration of %q+D with attribute "
- "%qs follows declaration with attribute %qs",
- newdecl, "always_inline", "noinline");
- else if (lookup_attribute ("cold", DECL_ATTRIBUTES (newdecl))
- && lookup_attribute ("hot", DECL_ATTRIBUTES (olddecl)))
- warned |= warning (OPT_Wattributes, "declaration of %q+D with attribute "
- "%qs follows declaration with attribute %qs",
- newdecl, "cold", "hot");
- else if (lookup_attribute ("hot", DECL_ATTRIBUTES (newdecl))
- && lookup_attribute ("cold", DECL_ATTRIBUTES (olddecl)))
- warned |= warning (OPT_Wattributes, "declaration of %q+D with attribute "
- "%qs follows declaration with attribute %qs",
- newdecl, "hot", "cold");
+ "%qs follows inline declaration ", newdecl, noinline);
+
return warned;
}
diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
index a54e121..5852c0d 100644
--- a/gcc/c/c-decl.c
+++ b/gcc/c/c-decl.c
@@ -4589,7 +4589,16 @@ c_decl_attributes (tree *node, tree attributes, int flags)
attributes = tree_cons (get_identifier ("omp declare target"),
NULL_TREE, attributes);
}
- return decl_attributes (node, attributes, flags);
+
+ /* Look up the current declaration with all the attributes merged
+ so far so that attributes on the current declaration that's
+ about to be pushed that conflict with the former can be detected,
+ diagnosed, and rejected as appropriate. */
+ tree last_decl = lookup_name (DECL_NAME (*node));
+ if (!last_decl)
+ last_decl = lookup_name_in_scope (DECL_NAME (*node), external_scope);
+
+ return decl_attributes (node, attributes, flags, last_decl);
}
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index b253ccc..0db600a 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -2490,9 +2490,14 @@ are automatically detected and this attribute is ignored.
@cindex @code{const} function attribute
@cindex functions that have no side effects
Many functions do not examine any values except their arguments, and
-have no effects except the return value. Basically this is just slightly
-more strict class than the @code{pure} attribute below, since function is not
-allowed to read global memory.
+have no effects except to return a value. Calls to such functions lend
+themselves to optimization such as common subexpression elimination.
+The @code{const} attribute imposes greater restrictions on a function's
+definition than the similar @code{pure} attribute below because it prohibits
+the function from reading global variables. Consequently, the presence of
+the attribute on a function declarations allows GCC to emit more efficient
+code for some calls to the function. Decorating the same function with
+both the @code{const} and the @code{pure} attribute is diagnnosed.
@cindex pointer arguments
Note that a function that has pointer arguments and examines the data
@@ -3144,7 +3149,7 @@ to prevent recursion.
@cindex functions that have no side effects
Many functions have no effects except the return value and their
return value depends only on the parameters and/or global variables.
-Such a function can be subject
+Calls to such functions can be subject
to common subexpression elimination and loop optimization just as an
arithmetic operator would be. These functions should be declared
with the attribute @code{pure}. For example,
@@ -3162,6 +3167,11 @@ Interesting non-pure functions are functions with infinite loops or those
depending on volatile memory or other system resource, that may change between
two consecutive calls (such as @code{feof} in a multithreading environment).
+The @code{pure} attribute imposes similar but looser restrictions on
+a function's defintion than the @code{const} attribute: it allows the
+function to read global variables. Decorating the same function with
+both the @code{pure} and the @code{const} attribute is diagnosed.
+
@item returns_nonnull
@cindex @code{returns_nonnull} function attribute
The @code{returns_nonnull} attribute specifies that the function
diff --git a/gcc/selftest-run-tests.c b/gcc/selftest-run-tests.c
index 30e476d..9af84a0 100644
--- a/gcc/selftest-run-tests.c
+++ b/gcc/selftest-run-tests.c
@@ -25,6 +25,8 @@ along with GCC; see the file COPYING3. If not see
#include "target.h"
#include "langhooks.h"
#include "options.h"
+#include "stringpool.h"
+#include "attribs.h"
/* This function needed to be split out from selftest.c as it references
tests from the whole source tree, and so is within
@@ -83,6 +85,7 @@ selftest::run_tests ()
spellcheck_c_tests ();
spellcheck_tree_c_tests ();
tree_cfg_c_tests ();
+ attribute_c_tests ();
/* This one relies on most of the above. */
function_tests_c_tests ();
diff --git a/gcc/selftest.h b/gcc/selftest.h
index 0572fef..608f4ee 100644
--- a/gcc/selftest.h
+++ b/gcc/selftest.h
@@ -170,6 +170,7 @@ extern const char *path_to_selftest_files;
/* Declarations for specific families of tests (by source file), in
alphabetical order. */
+extern void attribute_c_tests ();
extern void bitmap_c_tests ();
extern void diagnostic_c_tests ();
extern void diagnostic_show_locus_c_tests ();
diff --git a/gcc/testsuite/c-c++-common/attributes-3.c b/gcc/testsuite/c-c++-common/attributes-3.c
index 821278c..9d3a61c 100644
--- a/gcc/testsuite/c-c++-common/attributes-3.c
+++ b/gcc/testsuite/c-c++-common/attributes-3.c
@@ -12,16 +12,16 @@ extern __attribute__((noinline)) int fn1 (void); /* { dg-message "previous decla
extern inline int fn1 (void); /* { dg-warning "inline declaration of" } */
extern inline int fn2 (void); /* { dg-message "previous declaration" } */
-extern __attribute__((noinline)) int fn2 (void); /* { dg-warning "attribute noinline follows inline declaration" } */
+extern __attribute__((noinline)) int fn2 (void); /* { dg-warning "attribute .noinline. follows inline declaration" } */
extern __attribute__((always_inline)) int fn3 (void); /* { dg-message "previous declaration" } */
-extern __attribute__((noinline)) int fn3 (void); /* { dg-warning "attribute .noinline. follows declaration with attribute .always_inline." } */
+extern __attribute__((noinline)) int fn3 (void); /* { dg-warning "ignoring attribute .noinline. because it conflicts with attribute .always_inline." } */
extern __attribute__((noinline)) int fn4 (void); /* { dg-message "previous declaration" } */
-extern __attribute__((always_inline)) int fn4 (void); /* { dg-warning "attribute .always_inline. follows declaration with attribute .noinline." } */
+extern __attribute__((always_inline)) int fn4 (void); /* { dg-warning "ignoring attribute .always_inline. because it conflicts with attribute .noinline." } */
extern __attribute__((hot)) int fn5 (void); /* { dg-message "previous declaration" } */
-extern __attribute__((cold)) int fn5 (void); /* { dg-warning "attribute .cold. follows declaration with attribute .hot." } */
+extern __attribute__((cold)) int fn5 (void); /* { dg-warning "ignoring attribute .cold. because it conflicts with attribute .hot." } */
extern __attribute__((cold)) int fn6 (void); /* { dg-message "previous declaration" } */
-extern __attribute__((hot)) int fn6 (void); /* { dg-warning "attribute .hot. follows declaration with attribute .cold." } */
+extern __attribute__((hot)) int fn6 (void); /* { dg-warning "ignoring attribute .hot. because it conflicts with attribute .cold." } */
diff --git a/gcc/testsuite/gcc.dg/attr-noinline.c b/gcc/testsuite/gcc.dg/attr-noinline.c
index c2a5b1d..13cc660 100644
--- a/gcc/testsuite/gcc.dg/attr-noinline.c
+++ b/gcc/testsuite/gcc.dg/attr-noinline.c
@@ -17,7 +17,7 @@ static void function_declaration_both_after(void) {t();}
static void function_declaration_noinline_before(void) __attribute__((__noinline__)); /* { dg-message "note: previous declaration" } */
-static inline void function_declaration_noinline_before(void) {t();} /* { dg-warning "follows declaration with attribute noinline" } */
+static inline void function_declaration_noinline_before(void) {t();} /* { dg-warning "follows declaration with attribute .noinline." } */
static inline void function_declaration_noinline_after(void) {t();} /* { dg-message "note: previous definition" } */
@@ -41,7 +41,7 @@ static void function_declaration_inline_noinline_after(void) __attribute__((__no
static void function_declaration_noinline_inline_before(void) __attribute__((__noinline__)); /* { dg-message "note: previous declaration" } */
-static inline void function_declaration_noinline_inline_before(void); /* { dg-warning "follows declaration with attribute noinline" } */
+static inline void function_declaration_noinline_inline_before(void); /* { dg-warning "follows declaration with attribute .noinline." } */
static void function_declaration_noinline_inline_before(void) {t();}
diff --git a/gcc/testsuite/gcc.dg/pr44964.c b/gcc/testsuite/gcc.dg/pr44964.c
index 1df1bde..6c252ee 100644
--- a/gcc/testsuite/gcc.dg/pr44964.c
+++ b/gcc/testsuite/gcc.dg/pr44964.c
@@ -2,8 +2,9 @@
/* { dg-options "-fkeep-inline-functions -O" } */
static inline __attribute__ ((const))
-void baz (int i)
+int baz (int i)
{
+ return i;
}
static __attribute__ ((always_inline))
diff --git a/gcc/testsuite/gcc.dg/torture/pr42363.c b/gcc/testsuite/gcc.dg/torture/pr42363.c
index 9c9da13..ad0eac8 100644
--- a/gcc/testsuite/gcc.dg/torture/pr42363.c
+++ b/gcc/testsuite/gcc.dg/torture/pr42363.c
@@ -46,16 +46,18 @@ int bizr (void)
return i + 1;
}
-/* This might be regarded as pure and folded, rather than inlined.
- It's pure evil. */
+/* This might be regarded as pure and folded, rather than inlined,
+ but because it's pure evil it's diagnosed and the noreturn attribute
+ is dropped. The const attribute is dropped as well because it's
+ mutually exclusive with pure. */
static int __attribute__ ((pure, const, noreturn))
-barf (void)
-{
+barf (void) {
+ /* { dg-warning "ignoring attribute .const." "const" { target *-*-* } .-1 } */
+ /* { dg-warning "ignoring attribute .noreturn." "noreturn" { target *-*-* } .-2 } */
} /* { dg-warning "does return" } */
static int __attribute__ ((pure, const))
-bark (void)
-{
+bark (void) { /* { dg-warning "ignoring attribute .const." } */
barf ();
}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-2.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-2.c
index 146b76c..b8c5654 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-2.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-2.c
@@ -113,17 +113,18 @@ int test9 (int *intarr)
int test99 (int *intarr)
{
- extern int foo9 (int) __attribute__ ((pure));
+ extern int foo99 (int) __attribute__ ((pure));
int h, v;
g9 = 9;
- h = foo9 (g9);
+ h = foo99 (g9);
v = g9;
if (v != 9)
link_error ();
return g9;
}
-extern int foo99 (int);
+/* foo9 is const because of its declaration in test9. */
+extern int foo9 (int);
int test999 (int *arr)
{
@@ -134,10 +135,12 @@ int test999 (int *arr)
v1 = g9;
if (v1 != 9)
link_error ();
- l = foo99 (l);
+ l = foo9 (l);
return v1 + l;
}
+/* foo99 is pure because of its declaration in test99. */
+extern int foo9 (int);
int test9999 (void)
{
