016-07-21 Bernd Edlinger <bernd.edlinger@hotmail.de>

        PR middle-end/71876
        * calls.c (gimple_maybe_alloca_call_p): New function.  Return true
        if STMT may be an alloca call.
        (gimple_alloca_call_p, alloca_call_p): Return only true for the
        builtin alloca call.
        * calls.h (gimple_maybe_alloca_call_p): New function.
        * tree-inline.c (inline_forbidden_p_stmt): Use
        gimple_maybe_alloca_call_p here.

From-SVN: r238605

gcc/ChangeLog

+2016-07-21  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+	PR middle-end/71876
+	* calls.c (gimple_maybe_alloca_call_p): New function.  Return true
+	if STMT may be an alloca call.
+	(gimple_alloca_call_p, alloca_call_p): Return only true for the
+	builtin alloca call.
+	* calls.h (gimple_maybe_alloca_call_p): New function.
+	* tree-inline.c (inline_forbidden_p_stmt): Use
+	gimple_maybe_alloca_call_p here.
+
 2016-07-21  David Malcolm  <dmalcolm@redhat.com>
 
 	* spellcheck-tree.c (best_macro_match::best_macro_match):

gcc/calls.c

@@ -617,10 +617,10 @@ setjmp_call_p (const_tree fndecl)
 }
 
 
-/* Return true if STMT is an alloca call.  */
+/* Return true if STMT may be an alloca call.  */
 
 bool
-gimple_alloca_call_p (const gimple *stmt)
+gimple_maybe_alloca_call_p (const gimple *stmt)
 {
   tree fndecl;
 
@@ -634,7 +634,31 @@ gimple_alloca_call_p (const gimple *stmt)
   return false;
 }
 
-/* Return true when exp contains alloca call.  */
+/* Return true if STMT is a builtin alloca call.  */
+
+bool
+gimple_alloca_call_p (const gimple *stmt)
+{
+  tree fndecl;
+
+  if (!is_gimple_call (stmt))
+    return false;
+
+  fndecl = gimple_call_fndecl (stmt);
+  if (fndecl && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
+    switch (DECL_FUNCTION_CODE (fndecl))
+      {
+      case BUILT_IN_ALLOCA:
+      case BUILT_IN_ALLOCA_WITH_ALIGN:
+        return true;
+      default:
+	break;
+      }
+
+  return false;
+}
+
+/* Return true when exp contains a builtin alloca call.  */
 
 bool
 alloca_call_p (const_tree exp)
@@ -642,8 +666,16 @@ alloca_call_p (const_tree exp)
   tree fndecl;
   if (TREE_CODE (exp) == CALL_EXPR
       && (fndecl = get_callee_fndecl (exp))
-      && (special_function_p (fndecl, 0) & ECF_MAY_BE_ALLOCA))
-    return true;
+      && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
+    switch (DECL_FUNCTION_CODE (fndecl))
+      {
+      case BUILT_IN_ALLOCA:
+      case BUILT_IN_ALLOCA_WITH_ALIGN:
+        return true;
+      default:
+	break;
+      }
+
   return false;
 }
 

gcc/calls.h

@@ -23,6 +23,7 @@ along with GCC; see the file COPYING3.  If not see
 extern int flags_from_decl_or_type (const_tree);
 extern int call_expr_flags (const_tree);
 extern int setjmp_call_p (const_tree);
+extern bool gimple_maybe_alloca_call_p (const gimple *);
 extern bool gimple_alloca_call_p (const gimple *);
 extern bool alloca_call_p (const_tree);
 extern bool must_pass_in_stack_var_size (machine_mode, const_tree);

gcc/tree-inline.c

@@ -3577,7 +3577,7 @@ inline_forbidden_p_stmt (gimple_stmt_iterator *gsi, bool *handled_ops_p,
 	 RAM instead of 256MB.  Don't do so for alloca calls emitted for
 	 VLA objects as those can't cause unbounded growth (they're always
 	 wrapped inside stack_save/stack_restore regions.  */
-      if (gimple_alloca_call_p (stmt)
+      if (gimple_maybe_alloca_call_p (stmt)
 	  && !gimple_call_alloca_for_var_p (as_a <gcall *> (stmt))
 	  && !lookup_attribute ("always_inline", DECL_ATTRIBUTES (fn)))
 	{