https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71618
Bug ID: 71618
Summary: Improve C++ compilation by adding specific
optimization flags
Product: gcc
Version: 4.4.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: Roger.Jeurninck at gmail dot com
Target Milestone: ---
Hi,
I'm compiling C++ code together with gmock. Unfortunately this slows down the
compilation for one file to 10 minutes (using -g -O0)
Using one of the optimization levels (e.g. -O1) does improve the performance a
lot to a little more than 1 minute. Unfortunately this is not the best solution
as the code which is being compiled is being used for testing and debugging and
optimization might hamper this.
As a solution I try to pinpoint the optimization flag which does give this
beneficial compilation performance. The strange thing I do notice now that
proving 'g++ -O1' does not give the same result as providing the list of
optimization flags belonging to -O1. So what am I missing here?
----------------- Commands used --------------
about 1m30s => g++ -O1 -c <preproc.ii>
about 10m => g++ -fauto-inc-dec -fcprop-registers -fdce -fdefer-pop
-fdelayed-branch -fdse -fguess-branch-probability -fif-conversion2
-fif-conversion -finline-small-functions -fipa-pure-const -fipa-reference
-fmerge-constants -fsplit-wide-types -ftree-builtin-call-dce -ftree-ccp
-ftree-ch -ftree-copyrename -ftree-dce -ftree-dominator-opts -ftree-dse
-ftree-fre -ftree-sra -ftree-ter -funit-at-a-time -fomit-frame-pointer -c
<preproc.ii>
----------------- gcc specs ------------------
gcc -v
Using built-in specs.
Target: sparc-sun-solaris2.10
Configured with: ../configure --prefix=/cadappl/gcc/4.4.2/gcc
--enable-languages=c,c++,fortran,java
--with-gmp-lib=/shared/caddev/wblanken/5.10/gcc_4.4.2/gcc/4.4.2/SunOS_5.10/cadenv_home/cadlib:/usr/lib:/usr/ccs/lib:/usr/dt/lib:/usr/openwin/lib
--with-gmp-include=/shared/caddev/wblanken/5.10/gcc_4.4.2/gcc/4.4.2/SunOS_5.10/cadenv_home/cadinc
--with-mpfr-lib=/shared/caddev/wblanken/5.10/gcc_4.4.2/gcc/4.4.2/SunOS_5.10/cadenv_home/cadlib:/usr/lib:/usr/ccs/lib:/usr/dt/lib:/usr/openwin/lib
--with-mpfr-include=/shared/caddev/wblanken/5.10/gcc_4.4.2/gcc/4.4.2/SunOS_5.10/cadenv_home/cadinc
--without-gnu-as --with-ld=/usr/ccs/bin/as --without-gnu-ld
--with-ld=/usr/ccs/bin/ld --disable-nls
Thread model: posix
gcc version 4.4.2 (GCC)
