Description Dale Martin 2004-05-06 15:29:31 UTC

I work on an LGPL VHDL front-end and code generator called savant.  It is
implemented in C++.  We've been using g++-3.3 as our primary compiler for
the last few months.  With the annoucement of version 3.4 I have installed
g++-3.4 to experiment with.  (I run Debian Gnu/Linux, and I compiled the
experimental packages on my "woody" box.)  Overall I have found it to be
faster, more strict, and other good things so I was planning on moving to
it.

On one of our branches I noticed a problem.  Several files that compile
using "normal" amounts of memory - not in excess of 400M of virtual memory
- require more than 2G of virtual memory to compile with g++ 3.4.  These
source files do include a large and complex class heirarchy - one of the
classes is a factory for example, so it #includes a large number of files.
But 2G seems indicative of a problem.

Comment 1 Andrew Pinski 2004-05-06 15:33:46 UTC

Can you provide the preprocessed source?

Comment 2 Dale Martin 2004-05-06 15:43:50 UTC

Created attachment 6239 [details]
(One) file causing excessive memory consumption reported in 15320

Here is the command line used for compilation:
g++-3.4 -DHAVE_CONFIG_H -I. -I/work/dmartin/oss/savant.andy/src/analyzer
-I../../src -I/work/dmartin/oss/savant.andy/src
-I/work/dmartin/oss/savant.andy/src/aire
-I/work/dmartin/oss/savant.andy/src/aire/iir/visitor
-I/work/dmartin/oss/savant.andy/src/aire/iir/IIR
-I/work/dmartin/oss/savant.andy/src/aire/iir/IIRBase
-I/work/dmartin/oss/savant.andy/src/aire/iir/IIRScram
-I/work/dmartin/oss/savant.andy/src/visitors/module
-I/work/dmartin/oss/savant.andy/src/util
-I/work/dmartin/oss/savant.andy/src/analyzer -DDEVELOPER_ASSERTIONS
-DGENERATE_CC_REFERENCES -I/work/dmartin/local/3.4/include -I/usr/include/pccts
-I/work/dmartin/local/3.4/include -g -Wall -ggdb3 -ggdb3 -MT scram.lo -MD -MP
-MF .deps/scram.Tpo -c /work/dmartin/oss/savant.andy/src/analyzer/scram.cc 
-fPIC -DPIC

Comment 3 Andrew Pinski 2004-05-06 16:36:36 UTC

I can confirm that this takes a huge amount of memory at -O0, with -funit-at-a-time, it seems to take 
less memory but still big.

Comment 4 Giovanni Bajo 2004-05-15 00:24:42 UTC

Confirmed, a regression from 3.3.

Comment 5 Mark Mitchell 2004-08-18 18:47:38 UTC

For me, this seems to take about 527MB on an i686-pc-linux-gnu system using the
tip of the 3.4 branch in CVS.  Is this the file that was taking 2GB?

(I did fix a major memory overuse problem for complex class hierarchies recently.)

Comment 6 Dale Martin 2004-08-18 20:55:12 UTC

Subject: Re:  [3.4/3.5? Regression] Excessive memory consumption

On Wed, Aug 18, 2004 at 06:47:42PM -0000, mmitchel at gcc dot gnu dot org wrote:
> 
> ------- Additional Comments From mmitchel at gcc dot gnu dot org  2004-08-18 18:47 -------
> For me, this seems to take about 527MB on an i686-pc-linux-gnu system using the
> tip of the 3.4 branch in CVS.  Is this the file that was taking 2GB?
> 
> (I did fix a major memory overuse problem for complex class hierarchies recently.)

Yes, this is the file that was taking that much.  Will this be a 3.4.2 fix
or was it in 3.4.1?

Thanks!
	Dale

Comment 7 Mark Mitchell 2004-08-19 21:08:31 UTC

This will be in 3.4.2.

The mainline is doing better: 453 MB.

I've closed this PR.