Fix inliner ICE on alias with flatten attribute [PR92372]

gcc/ChangeLog:

2020-03-19  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/92372
	* cgraphunit.c (process_function_and_variable_attributes): warn
	for flatten attribute on alias.
	* ipa-inline.c (ipa_inline): Do not ICE on flatten attribute on alias.

gcc/testsuite/ChangeLog:

2020-03-19  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/92372
	* gcc.c-torture/pr92372.c: New test.
	* gcc.dg/attr-flatten-1.c: New test.

gcc/ChangeLog

+2020-03-19  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR ipa/92372
+	* cgraphunit.c (process_function_and_variable_attributes): warn
+	for flatten attribute on alias.
+	* ipa-inline.c (ipa_inline): Do not ICE on flatten attribute on alias.
+
 2020-03-19  Martin Liska  <mliska@suse.cz>
 
 	* lto-section-in.c: Add ext_symtab.

gcc/cgraphunit.c

@@ -851,6 +851,14 @@ process_function_and_variable_attributes (cgraph_node *first,
        node = symtab->next_function (node))
     {
       tree decl = node->decl;
+
+      if (node->alias
+	  && lookup_attribute ("flatten", DECL_ATTRIBUTES (decl)))
+	{
+	  warning_at (DECL_SOURCE_LOCATION (node->decl), OPT_Wattributes,
+		      "%<flatten%>"
+		      " attribute attribute is ignored on aliases");
+	}
       if (DECL_PRESERVE_P (decl))
 	node->mark_force_output ();
       else if (lookup_attribute ("externally_visible", DECL_ATTRIBUTES (decl)))

gcc/ipa-inline.c

@@ -2634,6 +2634,9 @@ ipa_inline (void)
     {
       node = order[i];
       if (node->definition
+	  /* Do not try to flatten aliases.  These may happen for example when
+	     creating local aliases.  */
+	  && !node->alias
 	  && lookup_attribute ("flatten",
 			       DECL_ATTRIBUTES (node->decl)) != NULL)
 	order[j--] = order[i];

gcc/testsuite/ChangeLog

+2020-03-19  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR ipa/92372
+	* gcc.c-torture/pr92372.c: New test.
+	* gcc.dg/attr-flatten-1.c: New test.
+
 2020-03-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/94211

gcc/testsuite/gcc.c-torture/pr92372.c

+int fn2(int);
+int fn3(int);
+
+__attribute__((flatten))
+int fn1(int p1)
+{
+  int a = fn2(p1);
+  return fn3(a);
+}
+__attribute__((flatten))
+int fn4(int p1)
+{
+  int j = fn2(p1);
+  return fn3(j);
+}
+

gcc/testsuite/gcc.dg/attr-flatten-1.c

+/* { dg-require-alias "" } */
+int fn2(int);
+int fn3(int);
+
+__attribute__((flatten))
+int fn1(int p1)
+{
+  int a = fn2(p1);
+  return fn3(a);
+}
+__attribute__((flatten))
+__attribute__((alias("fn1")))
+int fn4(int p1); /* { dg-warning "ignored" } */
+int
+test ()
+{
+  return fn4(1);
+}