A recent patch increased GCC's memory consumption!

[gcctest@suse.de]

Hi,

I am a friendly script caring about memory consumption in GCC.  Please
contact jh@suse.cz if something is going wrong.

Comparing memory consumption on compilation of combine.i, insn-attrtab.i,
and generate-3.4.ii I got:


comparing combine.c compilation at -O0 level:
  Amount of produced GGC garbage increased from 41308k to 41358k, overall 0.12%
    Overall memory needed: 24765k -> 24633k
    Peak memory use before GGC: 9582k -> 9586k
    Peak memory use after GGC: 8930k -> 8934k
    Maximum of released memory in single GGC run: 2754k
    Garbage: 41308k -> 41358k
    Leak: 6696k
    Overhead: 5810k -> 5818k
    GGC runs: 321

comparing combine.c compilation at -O1 level:
    Overall memory needed: 26808k
    Peak memory use before GGC: 17359k
    Peak memory use after GGC: 17170k
    Maximum of released memory in single GGC run: 2421k -> 2402k
    Garbage: 66319k -> 66339k
    Leak: 7186k
    Overhead: 7709k -> 7744k
    GGC runs: 415 -> 417

comparing combine.c compilation at -O2 level:
    Overall memory needed: 26808k
    Peak memory use before GGC: 17360k
    Peak memory use after GGC: 17170k
    Maximum of released memory in single GGC run: 2503k
    Garbage: 84713k -> 84729k
    Leak: 7426k
    Overhead: 10258k -> 10293k
    GGC runs: 483

comparing combine.c compilation at -O3 level:
    Overall memory needed: 27992k
    Peak memory use before GGC: 18803k
    Peak memory use after GGC: 17170k
    Maximum of released memory in single GGC run: 5454k
    Garbage: 127897k
    Leak: 7819k
    Overhead: 14858k
    GGC runs: 534

comparing insn-attrtab.c compilation at -O0 level:
    Overall memory needed: 81640k
    Peak memory use before GGC: 70259k
    Peak memory use after GGC: 44999k
    Maximum of released memory in single GGC run: 37046k
    Garbage: 149911k -> 149918k
    Leak: 11332k
    Overhead: 19105k -> 19106k
    GGC runs: 254

comparing insn-attrtab.c compilation at -O1 level:
    Overall memory needed: 114504k -> 114104k
    Peak memory use before GGC: 96264k
    Peak memory use after GGC: 85585k
    Maximum of released memory in single GGC run: 32777k
    Garbage: 295366k -> 295368k
    Leak: 11556k
    Overhead: 35957k -> 36054k
    GGC runs: 251

comparing insn-attrtab.c compilation at -O2 level:
    Overall memory needed: 125220k
    Peak memory use before GGC: 115314k -> 115312k
    Peak memory use after GGC: 85553k -> 85551k
    Maximum of released memory in single GGC run: 32461k
    Garbage: 381539k
    Leak: 11670k
    Overhead: 47771k -> 47864k
    GGC runs: 279

comparing insn-attrtab.c compilation at -O3 level:
    Overall memory needed: 125236k
    Peak memory use before GGC: 115335k
    Peak memory use after GGC: 85574k
    Maximum of released memory in single GGC run: 32787k
    Garbage: 382195k
    Leak: 11692k
    Overhead: 47930k
    GGC runs: 281

comparing Gerald's testcase PR8361 compilation at -O0 level:
    Overall memory needed: 118632k -> 118624k
    Peak memory use before GGC: 95340k -> 95333k
    Peak memory use after GGC: 94393k -> 94386k
    Maximum of released memory in single GGC run: 20159k -> 20160k
    Garbage: 224311k -> 224282k
    Leak: 49424k -> 49424k
    Overhead: 36947k -> 36953k
    GGC runs: 340 -> 341

comparing Gerald's testcase PR8361 compilation at -O1 level:
    Overall memory needed: 106072k
    Peak memory use before GGC: 94843k
    Peak memory use after GGC: 93892k
    Maximum of released memory in single GGC run: 19796k
    Garbage: 597088k -> 597266k
    Leak: 55690k -> 55674k
    Overhead: 69288k -> 69424k
    GGC runs: 520 -> 521

comparing Gerald's testcase PR8361 compilation at -O2 level:
    Overall memory needed: 106064k
    Peak memory use before GGC: 94843k
    Peak memory use after GGC: 93893k
    Maximum of released memory in single GGC run: 19796k
    Garbage: 679803k -> 679915k
    Leak: 56627k -> 56611k
    Overhead: 80498k -> 80632k
    GGC runs: 584

comparing Gerald's testcase PR8361 compilation at -O3 level:
    Overall memory needed: 108464k
    Peak memory use before GGC: 95603k
    Peak memory use after GGC: 94656k
    Maximum of released memory in single GGC run: 19694k
    Garbage: 726345k
    Leak: 56846k
    Overhead: 84354k
    GGC runs: 592

Head of the ChangeLog is:

--- /usr/src/SpecTests/sandbox-britten-memory/x86_64/mem-result/ChangeLog	2005-07-18 10:18:11.000000000 +0000
+++ /usr/src/SpecTests/sandbox-britten-memory/gcc/gcc/ChangeLog	2005-07-19 00:36:12.000000000 +0000
@@ -1,3 +1,18 @@
+2005-07-18  Ian Lance Taylor  <ian@airs.com>
+
+	PR middle-end/22057
+	* tree-cfgcleanup.c (cleanup_tree_cfg): Only remove forwarder
+	blocks when optimizing.
+
+2005-07-18  Steve Ellcey  <sje@cup.hp.com>
+
+	* common.opt (frename-registers): Initialize to 2.
+	(fweb): Ditto.
+	(fgcse-after-reload): Ditto.
+	* toplev.c (AUTODETECT_FLAG_VAR_TRACKING): Rename to AUTODETECT_VALUE.
+	(process_options): Only change flag_web, flag_rename_registers,
+	and flag_rerun_cse_after_loop if not explicitly set by user.
+
 2005-07-18  Jan Beulich  <jbeulich@novell.com>
 
 	* config/i386/i386.c (ix86_expand_branch, ix86_expand_setcc,


The results can be reproduced by building a compiler with

--enable-gather-detailed-mem-stats targetting x86-64

and compiling preprocessed combine.c or testcase from PR8632 with:

-fmem-report --param=ggc-min-heapsize=1024 --param=ggc-min-expand=1 -Ox -Q

The memory consumption summary appears in the dump after detailed listing
of the places they are allocated in.  Peak memory consumption is actually
computed by looking for maximal value in {GC XXXX -> YYYY} report.

Your testing script.