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[Bug preprocessor/53525] Performance regression due to enabling track-macro-expansion
- From: "jimis at gmx dot net" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 30 May 2012 04:44:54 +0000
- Subject: [Bug preprocessor/53525] Performance regression due to enabling track-macro-expansion
- Auto-submitted: auto-generated
- References: <bug-53525-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53525
--- Comment #2 from jimis <jimis at gmx dot net> 2012-05-30 04:44:54 UTC ---
According to valgrind major overhead is due to numerous calls of
line-map.c:linemap_line_start() that actually allocate new line_maps. This
happens because we are resetting the max_column_hint whenever we enter macro
context in enter_macro_context()->linemap_enter_macro().
The following one-liner seems to resolve this, as run time is improved by about
7ms or 45 M Instr.
=== modified file 'libcpp/line-map.c'
--- libcpp/line-map.c 2012-04-30 11:42:12 +0000
+++ libcpp/line-map.c 2012-05-27 06:52:08 +0000
@@ -331,7 +331,6 @@ linemap_enter_macro (struct line_maps *s
num_tokens * sizeof (source_location));
LINEMAPS_MACRO_CACHE (set) = LINEMAPS_MACRO_USED (set) - 1;
- set->max_column_hint = 0;
return map;
}