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[Bug c/12245] [4.2/4.3/4.4 regression] Uses lots of memory when compiling large initialized arrays
- From: "hubicka at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 22 Feb 2009 11:21:10 -0000
- Subject: [Bug c/12245] [4.2/4.3/4.4 regression] Uses lots of memory when compiling large initialized arrays
- References: <bug-12245-6931@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #42 from hubicka at gcc dot gnu dot org 2009-02-22 11:21 -------
Actual representation of constructor don't seem to be major problem here.
We seem to build _a lot_ (117MB) of CONVERT exprs just to call fold on it and
convert integer to proper type, so counting in INTEGER_CSTs should be just
slightly less than half of memory needed. This seems quite silly.
The patch to not use HOST_WIDE_INT or similar for counting should save another
70MB of garbage (and speed up compilation), so perhaps you could dig it out?
:))
Following patch:
Index: convert.c
===================================================================
--- convert.c (revision 144352)
+++ convert.c (working copy)
@@ -749,6 +749,11 @@ convert_to_integer (tree type, tree expr
break;
}
+ /* When parsing long initializers, we might end up with a lot of casts.
+ Shortcut this. */
+ if (TREE_CODE (expr) == INTEGER_CST)
+ return fold_unary (CONVERT_EXPR, type, expr);
+
return build1 (CONVERT_EXPR, type, expr);
case REAL_TYPE:
Cuts gabrage production in half:
c-typeck.c:6472 (output_init_element) 0: 0.0%
47910400:100.0% 45541112:23.7% 26342936:99.5% 19
ggc-common.c:187 (ggc_calloc) 67094608:46.1% 0:
0.0% 67162736:34.9% 1088: 0.0% 58
tree.c:1004 (build_int_cst_wide) 78264768:53.8% 0:
0.0% 78266496:40.7% 0: 0.0% 3261068
Total 145570627 47910416
192171521 26481588 3275033
source location Garbage Freed
Leak Overhead Times
I will give the patch testing, but I am not too hopeful it will just work. ;)
Honza
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12245