Generate a call to a .ACCESS_WITH_SIZE for a FAM with counted_by attribute only when it's read from.

Currently, we generate a call to a .ACCESS_WITH_SIZE for a FAM with counted_by
attribute for every component_ref that corresponds to such an object.
Actually, such .ACCESS_WITH_SIZE calls are useless when they are generated
for a written site or an address taken site.

In this patch, we only generate a call to .ACCESS_WITH_SIZE for a FAM with
counted_by attribute when it's a read.

gcc/c/ChangeLog:

	* c-tree.h (handle_counted_by_for_component_ref): New prototype of
	build_component_ref and handle_counted_by_for_component_ref.
	* c-parser.cc (c_parser_postfix_expression): Call the new prototypes
	of build_component_ref and handle_counted_by_for_component_ref,
	update comments.
	* c-typeck.cc (default_function_array_read_conversion): Likewise.
	(convert_lvalue_to_rvalue): Likewise.
	(default_conversion): Likewise.
	(handle_counted_by_p): Update comments.
	(handle_counted_by_for_component_ref): Delete one argument.
	(build_component_ref): Delete one argument. Delete the call to
	handle_counted_by_for_component_ref completely.
	(build_array_ref): Generate call to .ACCESS_WITH_SIZE for array.

gcc/testsuite/ChangeLog:

	* gcc.dg/flex-array-counted-by-2.c: Adjust testing case.

4 files changed, 21 insertions, 37 deletions

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 148cd9a..510d727 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -11876,12 +11876,9 @@ c_parser_postfix_expression (c_parser *parser)
 	    if (c_parser_next_token_is (parser, CPP_NAME))
 	      {
 		c_token *comp_tok = c_parser_peek_token (parser);
-		/* Ignore the counted_by attribute for reference inside
-		   offsetof since the information is not useful at all.  */
 		offsetof_ref
 		  = build_component_ref (loc, offsetof_ref, comp_tok->value,
-					 comp_tok->location, UNKNOWN_LOCATION,
-					 false);
+					 comp_tok->location, UNKNOWN_LOCATION);
 		c_parser_consume_token (parser);
 		while (c_parser_next_token_is (parser, CPP_DOT)
 		       || c_parser_next_token_is (parser,
@@ -11908,14 +11905,11 @@ c_parser_postfix_expression (c_parser *parser)
 			    break;
 			  }
 			c_token *comp_tok = c_parser_peek_token (parser);
-			/* Ignore the counted_by attribute for reference inside
-			   offsetof since the information is not useful.  */
 			offsetof_ref
 			  = build_component_ref (loc, offsetof_ref,
 						 comp_tok->value,
 						 comp_tok->location,
-						 UNKNOWN_LOCATION,
-						 false);
+						 UNKNOWN_LOCATION);
 			c_parser_consume_token (parser);
 		      }
 		    else
@@ -12701,8 +12695,8 @@ c_parser_postfix_expression (c_parser *parser)
 	    /* If the array ref is inside TYPEOF or ALIGNOF, the call to
 	       .ACCESS_WITH_SIZE was not generated by the routine
 	       build_component_ref by default, we should generate it here.  */
-	    if ((in_typeof || in_alignof) && TREE_CODE (ref) == COMPONENT_REF)
-	      ref = handle_counted_by_for_component_ref (loc, ref, false);
+	    if (TREE_CODE (ref) == COMPONENT_REF)
+	      ref = handle_counted_by_for_component_ref (loc, ref);
 
 	    if (has_counted_by_object (ref))
 	      expr.value = get_counted_by_ref (ref);
diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h
index b8c81f6..afec03e2 100644
--- a/gcc/c/c-tree.h
+++ b/gcc/c/c-tree.h
@@ -821,8 +821,8 @@ extern void mark_exp_read (tree);
 extern tree composite_type (tree, tree);
 extern tree lookup_field (const_tree, tree);
 extern tree build_component_ref (location_t, tree, tree, location_t,
-				 location_t, bool = true);
-extern tree handle_counted_by_for_component_ref (location_t, tree, bool);
+				 location_t);
+extern tree handle_counted_by_for_component_ref (location_t, tree);
 extern tree build_array_ref (location_t, tree, tree);
 extern tree build_omp_array_section (location_t, tree, tree, tree);
 extern tree build_external_ref (location_t, tree, bool, tree *);
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 9ea58e1..3c6f7d9 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -2487,11 +2487,10 @@ struct c_expr
 default_function_array_read_conversion (location_t loc, struct c_expr exp)
 {
   mark_exp_read (exp.value);
-  /* We only generate a call to .ACCESS_WITH_SIZE for a pointer field when
-     it is a read.  */
+  /* We only generate a call to .ACCESS_WITH_SIZE when it is a read.  */
   if (TREE_CODE (exp.value) == COMPONENT_REF
       && handle_counted_by_p (exp.value))
-    exp.value = handle_counted_by_for_component_ref (loc, exp.value, true);
+    exp.value = handle_counted_by_for_component_ref (loc, exp.value);
   return default_function_array_conversion (loc, exp);
 }
 
@@ -2593,11 +2592,10 @@ convert_lvalue_to_rvalue (location_t loc, struct c_expr exp,
   bool force_non_npc = false;
   if (read_p)
     mark_exp_read (exp.value);
-  /* We only generate a call to .ACCESS_WITH_SIZE for a pointer field when
-     it is a read.  */
+  /* We only generate a call to .ACCESS_WITH_SIZE when it is a read.  */
   if (read_p && TREE_CODE (exp.value) == COMPONENT_REF
       && handle_counted_by_p (exp.value))
-    exp.value = handle_counted_by_for_component_ref (loc, exp.value, true);
+    exp.value = handle_counted_by_for_component_ref (loc, exp.value);
 
   if (convert_p)
     exp = default_function_array_conversion (loc, exp);
@@ -2776,11 +2774,10 @@ default_conversion (tree exp)
   tree promoted_type;
 
   mark_exp_read (exp);
-  /* We only generate a call to .ACCESS_WITH_SIZE for a pointer field when
-     it is a read.  */
+  /* We only generate a call to .ACCESS_WITH_SIZE when it is a read.  */
   if (TREE_CODE (exp) == COMPONENT_REF
       && handle_counted_by_p (exp))
-    exp = handle_counted_by_for_component_ref (EXPR_LOCATION (exp), exp, true);
+    exp = handle_counted_by_for_component_ref (EXPR_LOCATION (exp), exp);
 
   /* Functions and arrays have been converted during parsing.  */
   gcc_assert (code != FUNCTION_TYPE);
@@ -3193,12 +3190,10 @@ build_access_with_size_for_counted_by (location_t loc, tree ref,
 /* For the COMPONENT_REF ref, check whether it has a counted_by attribute,
    if so, wrap this COMPONENT_REF with the corresponding CALL to the
    function .ACCESS_WITH_SIZE.
-   Otherwise, return the ref itself.
-   FOR_POINTER is true when this is for pointer field.  */
+   Otherwise, return the ref itself.  */
 
 tree
-handle_counted_by_for_component_ref (location_t loc, tree ref,
-				     bool for_pointer)
+handle_counted_by_for_component_ref (location_t loc, tree ref)
 {
   gcc_assert (TREE_CODE (ref) == COMPONENT_REF);
   tree datum = TREE_OPERAND (ref, 0);
@@ -3209,11 +3204,6 @@ handle_counted_by_for_component_ref (location_t loc, tree ref,
 	|| TREE_CODE (TREE_TYPE (ref)) == POINTER_TYPE))
     return ref;
 
-  bool is_fam = c_flexible_array_member_type_p (TREE_TYPE (ref));
-
-  if (!(is_fam ^ for_pointer))
-    return ref;
-
   tree counted_by_ref = build_counted_by_ref (datum, subdatum,
 					      &counted_by_type);
   if (counted_by_ref)
@@ -3233,8 +3223,7 @@ handle_counted_by_for_component_ref (location_t loc, tree ref,
 
 tree
 build_component_ref (location_t loc, tree datum, tree component,
-		     location_t component_loc, location_t arrow_loc,
-		     bool handle_counted_by)
+		     location_t component_loc, location_t arrow_loc)
 {
   tree type = TREE_TYPE (datum);
   enum tree_code code = TREE_CODE (type);
@@ -3306,8 +3295,6 @@ build_component_ref (location_t loc, tree datum, tree component,
 	  int quals;
 	  tree subtype;
 	  bool use_datum_quals;
-	  /* Do not handle counted_by when in typeof and alignof operator.  */
-	  handle_counted_by = handle_counted_by && !in_typeof && !in_alignof;
 
 	  if (TREE_TYPE (subdatum) == error_mark_node)
 	    return error_mark_node;
@@ -3329,8 +3316,6 @@ build_component_ref (location_t loc, tree datum, tree component,
 	  SET_EXPR_LOCATION (ref, loc);
 
 	  check_counted_by_attribute (loc, ref);
-	  if (handle_counted_by)
-	    ref = handle_counted_by_for_component_ref (loc, ref, false);
 
 	  if (TREE_READONLY (subdatum)
 	      || (use_datum_quals && TREE_READONLY (datum)))
@@ -3517,6 +3502,11 @@ build_array_ref (location_t loc, tree array, tree index)
   bool was_vector = VECTOR_TYPE_P (TREE_TYPE (array));
   bool non_lvalue = convert_vector_to_array_for_subscript (loc, &array, index);
 
+  /* We only generate a call to .ACCESS_WITH_SIZE when it is a read.  */
+  if (TREE_CODE (array) == COMPONENT_REF
+      && handle_counted_by_p (array))
+    array = handle_counted_by_for_component_ref (loc, array);
+
   if (TREE_CODE (TREE_TYPE (array)) == ARRAY_TYPE)
     {
       tree rval, type;
diff --git a/gcc/testsuite/gcc.dg/flex-array-counted-by-2.c b/gcc/testsuite/gcc.dg/flex-array-counted-by-2.c
index 42d6436..a9bec2d 100644
--- a/gcc/testsuite/gcc.dg/flex-array-counted-by-2.c
+++ b/gcc/testsuite/gcc.dg/flex-array-counted-by-2.c
@@ -111,4 +111,4 @@ int main(int argc, char *argv[])
   return 0;
 }
 
-/* { dg-final { scan-tree-dump-times "ACCESS_WITH_SIZE" 8 "original" } } */
+/* { dg-final { scan-tree-dump-times "ACCESS_WITH_SIZE" 6 "original" } } */