calls.c: refactor special_function_p for use by analyzer (v2)

This patch refactors some code in special_function_p that checks for
the function being sane to match by name, splitting it out into a new
maybe_special_function_p, and using it it two places in the analyzer.

gcc/analyzer/ChangeLog:
	* analyzer.cc (is_named_call_p): Replace tests for fndecl being
	extern at file scope and having a non-NULL DECL_NAME with a call
	to maybe_special_function_p.
	* function-set.cc (function_set::contains_decl_p): Add call to
	maybe_special_function_p.

gcc/ChangeLog:
	* calls.c (special_function_p): Split out the check for DECL_NAME
	being non-NULL and fndecl being extern at file scope into a
	new maybe_special_function_p and call it.  Drop check for fndecl
	being non-NULL that was after a usage of DECL_NAME (fndecl).
	* tree.h (maybe_special_function_p): New inline function.

gcc/ChangeLog

@@ -1,3 +1,11 @@
+2020-01-31  David Malcolm  <dmalcolm@redhat.com>
+
+	* calls.c (special_function_p): Split out the check for DECL_NAME
+	being non-NULL and fndecl being extern at file scope into a
+	new maybe_special_function_p and call it.  Drop check for fndecl
+	being non-NULL that was after a usage of DECL_NAME (fndecl).
+	* tree.h (maybe_special_function_p): New inline function.
+
 2020-01-30  Andrew Stubbs  <ams@codesourcery.com>
 
 	* config/gcn/gcn-valu.md (gather<mode>_exec): Move contents ...

gcc/analyzer/ChangeLog

@@ -1,3 +1,11 @@
+2020-01-31  David Malcolm  <dmalcolm@redhat.com>
+
+	* analyzer.cc (is_named_call_p): Replace tests for fndecl being
+	extern at file scope and having a non-NULL DECL_NAME with a call
+	to maybe_special_function_p.
+	* function-set.cc (function_set::contains_decl_p): Add call to
+	maybe_special_function_p.
+
 2020-01-31  David Malcolm  <dmalcolm@redhat.com>
 
 	PR analyzer/93450

gcc/analyzer/analyzer.cc

@@ -65,18 +65,10 @@ is_named_call_p (tree fndecl, const char *funcname)
   gcc_assert (fndecl);
   gcc_assert (funcname);
 
-  /* Exclude functions not at the file scope, or not `extern',
-     since they are not the magic functions we would otherwise
-     think they are.  */
-  if (!((DECL_CONTEXT (fndecl) == NULL_TREE
-	 || TREE_CODE (DECL_CONTEXT (fndecl)) == TRANSLATION_UNIT_DECL)
-	&& TREE_PUBLIC (fndecl)))
+  if (!maybe_special_function_p (fndecl))
     return false;
 
   tree identifier = DECL_NAME (fndecl);
-  if (identifier == NULL)
-    return false;
-
   const char *name = IDENTIFIER_POINTER (identifier);
   const char *tname = name;
 

gcc/analyzer/function-set.cc

@@ -59,6 +59,8 @@ bool
 function_set::contains_decl_p (tree fndecl) const
 {
   gcc_assert (fndecl && DECL_P (fndecl));
+  if (!maybe_special_function_p (fndecl))
+    return false;
   return contains_name_p (IDENTIFIER_POINTER (DECL_NAME (fndecl)));
 }
 

gcc/calls.c

@@ -586,18 +586,8 @@ special_function_p (const_tree fndecl, int flags)
 {
   tree name_decl = DECL_NAME (fndecl);
 
-  if (fndecl && name_decl
-      && IDENTIFIER_LENGTH (name_decl) <= 11
-      /* Exclude functions not at the file scope, or not `extern',
-	 since they are not the magic functions we would otherwise
-	 think they are.
-	 FIXME: this should be handled with attributes, not with this
-	 hacky imitation of DECL_ASSEMBLER_NAME.  It's (also) wrong
-	 because you can declare fork() inside a function if you
-	 wish.  */
-      && (DECL_CONTEXT (fndecl) == NULL_TREE
-	  || TREE_CODE (DECL_CONTEXT (fndecl)) == TRANSLATION_UNIT_DECL)
-      && TREE_PUBLIC (fndecl))
+  if (maybe_special_function_p (fndecl)
+      && IDENTIFIER_LENGTH (name_decl) <= 11)
     {
       const char *name = IDENTIFIER_POINTER (name_decl);
       const char *tname = name;

gcc/tree.h

@@ -5611,6 +5611,31 @@ builtin_decl_declared_p (enum built_in_function fncode)
 	  && builtin_info[uns_fncode].declared_p);
 }
 
+/* Determine if the function identified by FNDECL is one that
+   makes sense to match by name, for those places where we detect
+   "magic" functions by name.
+
+   Return true if FNDECL has a name and is an extern fndecl at file scope.
+   FNDECL must be a non-NULL decl.
+
+   Avoid using this, as it's generally better to use attributes rather
+   than to check for functions by name.  */
+
+static inline bool
+maybe_special_function_p (const_tree fndecl)
+{
+  tree name_decl = DECL_NAME (fndecl);
+  if (name_decl
+      /* Exclude functions not at the file scope, or not `extern',
+	 since they are not the magic functions we would otherwise
+	 think they are.  */
+      && (DECL_CONTEXT (fndecl) == NULL_TREE
+	  || TREE_CODE (DECL_CONTEXT (fndecl)) == TRANSLATION_UNIT_DECL)
+      && TREE_PUBLIC (fndecl))
+    return true;
+  return false;
+}
+
 /* Return true if T (assumed to be a DECL) is a global variable.
    A variable is considered global if its storage is not automatic.  */