The objc front-end contains many loops that are N^2. For example, most uses of
chainon should be changed to either build the list backwards are reverse it
(both for straight-line code and for loops). Some trivial examples from
objc-act.c:
---
for (t = TYPE_NEXT_VARIANT (s); t; t = TYPE_NEXT_VARIANT (t))
objc_info = chainon (objc_info, build_tree_list (NULL_TREE, TYPE_OBJC_INFO
(t)));
---
---
/* SEL *refs; */
field_decl = create_field_decl (build_pointer_type (objc_selector_type),
"refs");
chainon (field_decl_chain, field_decl);
/* short cls_def_cnt; */
field_decl = create_field_decl (short_integer_type_node, "cls_def_cnt");
chainon (field_decl_chain, field_decl);
/* short cat_def_cnt; */
field_decl = create_field_decl (short_integer_type_node, "cat_def_cnt");
chainon (field_decl_chain, field_decl);
---
---
for (j = 1; j < i; j++) {
sprintf (buffer, "c%d", j + 1);
field_decl = create_field_decl (char_type_node,
buffer);
chainon (field_decl_chain, field_decl);
}
---
-Chris
--
Summary: many N^2 loops in objc frontend
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: objc
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: sabre at nondot dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24867
