re PR c/70255 (change of the order of summation of floating point numbers despite no-associative-math)

	PR c/70255
	* c-decl.c (diagnose_mismatched_decls): Warn for optimize attribute
	on a declaration following the definition.

	* gcc.dg/attr-opt-1.c: New test.

From-SVN: r236071

4 files changed, 60 insertions, 0 deletions

diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index 49c9064..9387c73 100644
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,3 +1,9 @@
+2016-05-10  Marek Polacek  <polacek@redhat.com>
+
+	PR c/70255
+	* c-decl.c (diagnose_mismatched_decls): Warn for optimize attribute
+	on a declaration following the definition.
+
 2016-05-05  Jakub Jelinek  <jakub@redhat.com>
 
 	* c-parser.c (c_parser_switch_statement): Add IF_P argument,
diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
index 7094efc..9c09536 100644
--- a/gcc/c/c-decl.c
+++ b/gcc/c/c-decl.c
@@ -2228,6 +2228,18 @@ diagnose_mismatched_decls (tree newdecl, tree olddecl,
 
   if (TREE_CODE (newdecl) == FUNCTION_DECL)
     {
+      tree a1 = lookup_attribute ("optimize", DECL_ATTRIBUTES (olddecl));
+      tree a2 = lookup_attribute ("optimize", DECL_ATTRIBUTES (newdecl));
+      /* An optimization attribute applied on a declaration after the
+	 definition is likely not what the user wanted.  */
+      if (a2 != NULL_TREE
+	  && DECL_SAVED_TREE (olddecl) != NULL_TREE
+	  && (a1 == NULL_TREE || !attribute_list_equal (a1, a2)))
+	warned |= warning (OPT_Wattributes,
+			   "optimization attribute on %qD follows "
+			   "definition but the attribute doesn%'t match",
+			   newdecl);
+
       /* Diagnose inline __attribute__ ((noinline)) which is silly.  */
       if (DECL_DECLARED_INLINE_P (newdecl)
 	  && lookup_attribute ("noinline", DECL_ATTRIBUTES (olddecl)))
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 08392c7..4f3cc5d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-05-10  Marek Polacek  <polacek@redhat.com>
+
+	PR c/70255
+	* gcc.dg/attr-opt-1.c: New test.
+
 2016-05-10  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/70497
diff --git a/gcc/testsuite/gcc.dg/attr-opt-1.c b/gcc/testsuite/gcc.dg/attr-opt-1.c
new file mode 100644
index 0000000..4140fda
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/attr-opt-1.c
@@ -0,0 +1,37 @@
+/* PR c/70255 */
+/* { dg-do compile } */
+
+double
+fn1 (double h, double l) /* { dg-message "previous definition" } */
+{
+  return h + l;
+}
+double fn1 (double, double) __attribute__ ((optimize ("no-associative-math"))); /* { dg-warning "optimization attribute on .fn1. follows definition" } */
+
+__attribute__ ((optimize ("no-associative-math"))) double
+fn2 (double h, double l)
+{
+  return h + l;
+}
+double fn2 (double, double) __attribute__ ((optimize ("no-associative-math")));
+
+__attribute__ ((optimize ("no-associative-math"))) double
+fn3 (double h, double l) /* { dg-message "previous definition" } */
+{
+  return h + l;
+}
+double fn3 (double, double) __attribute__ ((optimize ("O2,no-associative-math"))); /* { dg-warning "optimization attribute on .fn3. follows definition" } */
+
+__attribute__ ((optimize ("no-associative-math,O2"))) double
+fn4 (double h, double l) /* { dg-message "previous definition" } */
+{
+  return h + l;
+}
+double fn4 (double, double) __attribute__ ((optimize ("O2,no-associative-math"))); /* { dg-warning "optimization attribute on .fn4. follows definition" } */
+
+__attribute__ ((optimize ("no-reciprocal-math"), optimize ("no-associative-math"))) int
+fn5 (void)
+{
+  return 0;
+}
+int __attribute__ ((optimize ("no-associative-math"), optimize ("no-reciprocal-math"))) fn5 (void);