c++: extend cold, hot attributes to classes

Most code is cold. This patch extends support for attribute ((cold)) to C++
Classes, Unions, and Structs (RECORD_TYPES and UNION_TYPES) to benefit from
encapsulation - reducing the verbosity of using the attribute where
deserved. The ((hot)) attribute is also extended for its semantic relation.

gcc/c-family/ChangeLog:

	* c-attribs.cc (handle_hot_attribute): remove warning on
	RECORD_TYPE and UNION_TYPE when in c_dialect_xx.
	(handle_cold_attribute): Likewise.

gcc/cp/ChangeLog:

	* class.cc (propagate_class_warmth_attribute): New function.
	(check_bases_and_members): propagate hot and cold attributes
	to all FUNCTION_DECL when the record is marked hot or cold.
	* cp-tree.h (maybe_propagate_warmth_attributes): New function.
	* decl2.cc (maybe_propagate_warmth_attributes): New function.
	* method.cc (lazily_declare_fn): propagate hot and cold
	attributes to lazily declared functions when the record is
	marked hot or cold.

gcc/ChangeLog:

	* doc/extend.texi: Document attributes hot, cold on C++ types.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/attr-hotness.C: New test.

Signed-off-by: Javier Martinez <javier.martinez.bugzilla@gmail.com>
Reviewed-by: Jason Merrill <jason@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc
index 4ba0017..a70dd5d 100644
--- a/gcc/cp/method.cc
+++ b/gcc/cp/method.cc
@@ -3592,6 +3592,12 @@ lazily_declare_fn (special_function_kind sfk, tree type)
     /* Create appropriate clones.  */
     clone_cdtor (fn, /*update_methods=*/true);
 
+  /* Classes, structs or unions TYPE marked with hotness attributes propagate
+     the attribute to all methods.  This is typically done in
+     check_bases_and_members, but we must also inject them here for deferred
+     lazily-declared functions.  */
+  maybe_propagate_warmth_attributes (fn, type);
+
   return fn;
 }