GCC 4.5 testing

devsk · Posted: Sun Aug 08, 2010 6:43 pm Post subject:

Continuing my ricer streak, I compiled p7zip with -O3 instead of -O2, and I gain 5% speed. I think that's it for the day!

cruzki123 · Apprentice Joined: 16 May 2008 Posts: 262

devsk · Posted: Sun Aug 08, 2010 8:26 pm Post subject:

xibo · Posted: Sun Aug 08, 2010 9:05 pm Post subject:

i guess -fforce-addr was re-added by the gentoo patches. according to gcc's mailing list it often produces worse code there's no situation where it produces better one ( and was removed from mainline gcc for being buggy )...

i wonder whether it really makes things faster?

kernelOfTruth · Posted: Sun Aug 08, 2010 9:30 pm Post subject:

xibo · Posted: Sun Aug 08, 2010 9:34 pm Post subject:

<-- just tried using it

interresting. i have a vanilla build of gcc-4.5.1, and passing -fforce-addr does not cause an error or warning. It's not in the man page though, that's why i looked it up in the web and found the mailing list archive stating it was removed for 4.3...

wrc1944 · Posted: Sun Aug 08, 2010 10:59 pm Post subject:

devsk,
On my main ~xf86 box I tried to enable USE=graphite and -floop-interchange -floop-strip-mine -floop-block in make.conf, but when I tried emerge gcc I couldn't get dev-libs/mpc to compile. It fails immediately with the "c compiler can't create executables" error. Same thing happeded on my backup ~x86 box, but NOT on my ~amd64 Gentoo installation.

When I disable graphite and removed the "graphite" cflags, everything compiles and installs fine. I now have rebuild my toolchain with gcc-4.5.1.

How are you enabling graphite successfully on ~x86 (if you are)?

Or, am I doing it wrong, and should have enabled graphite flags only AFTER I had already successfully installed and switched to gcc-4.5.1 with gcc-config?

Does all this look correct?

devsk · Posted: Mon Aug 09, 2010 12:47 am Post subject:

USE=graphite can be enabled anytime. -floop* CFLAGS can be used only when you are using the GCC which was emerged with USE=graphite. So,

1. Make sure CFLAGS don't have -floop*.
2. Enable graphite.
3. Emerge GCC (4.4 or 4.5)
4. Switch gcc to 4.5 if you are now moving to 4.5
5. Log out and login.
6. Add -floop* CFLAGS in make.conf.
7. Compile away!

wrc1944 · Posted: Mon Aug 09, 2010 12:57 am Post subject:

Thanks much, devsk!

That was my mistake- I was trying to emerge 4.5.1 with graphite and -floop* flags, but with my gcc-4.4 which had been compiled without them.

I'll do as per your procedure. I was really hoping to get this done before the big kde-4.5 updates coming up.

Again, many thanks for the details about graphite- I really appreciate it!

EDIT: AHA! This time, the output says gcc is being configured with:

cruzki123 · Apprentice Joined: 16 May 2008 Posts: 262

wrc1944 · Posted: Mon Aug 09, 2010 4:45 pm Post subject:

OK

Just finished up an emerge -e @system (282 packages) with graphite enabled on my ~x86 main box (mentioned above), with only one minor known and problem- the mysql-5.1.46 failure on rebuild. Guess we're still waiting for the 5.1.49 fixes as mentioned in this thread recently, so no big deal. I'm assuming the old version is still in place and working.

All set for the big kde 4.5 updates being compiled with gcc-4.5.1.

BTW, my current cflags on this box:

kernelOfTruth · Posted: Mon Aug 09, 2010 5:51 pm Post subject:

wrc1944 · Posted: Mon Aug 09, 2010 8:01 pm Post subject:

Added -fgraphite-identity globally, and did an emerge --sync. The Mysql problem is now fixed in 5.1.49-r1:

Etal · Veteran Joined: 15 Jul 2005 Posts: 1931

What does -fgraphite-identity actually do?

From my understanding, it converts gimple to graphite and then back again with the intention of debugging graphite. If the -floop* flags are enabled, wouldn't they do that anyway?

devsk · Posted: Tue Aug 10, 2010 1:21 am Post subject:

Etal · Veteran Joined: 15 Jul 2005 Posts: 1931

Well, if you search for "fgraphite-identity," you get this:

wrc1944 · Posted: Tue Aug 10, 2010 4:13 am Post subject:

Maybe I'm misunderstanding, but this graphite-identity info now seems confusing, and even a bit contradictory. I'm not sure if it adds any performance improvement, or is mainly just useful for debugging. I'm not sure I understand the benefit (if any) in having it enabled, if my main objective is simply performance and not debugging.
_________________
Main box- AsRock x370 Gaming K4
Ryzen 7 3700x, 3.6GHz, 16GB GSkill Flare DDR4 3200mhz
Samsung SATA 1000GB, Radeon HD R7 350 2GB DDR5
OpenRC Gentoo ~amd64 plasma, glibc-2.36-r7, gcc-13.2.1_p20230304
kernel-6.8.4 USE=experimental python3_11

mv · Watchman Joined: 20 Apr 2005 Posts: 6747

ssteinberg · Apprentice Joined: 09 Jul 2010 Posts: 206 Location: Israel

Multiple packages give:
/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.1/../../../../x86_64-pc-linux-gnu/bin/ld: /var/tmp/portage/sys-libs/zlib-1.2.3-r1/temp/ccEKdzkK.lto.o: relocation R_X86_64_PC32 against symbol `deflateInit_' can not be used when making a shared object; recompile with -fPIC
when compiling and linking with lto.
At the moment I have more packages blacklisting lto in /etc/portage/env then packages that compile fine.

mv · Watchman Joined: 20 Apr 2005 Posts: 6747

devsk · Posted: Thu Aug 12, 2010 5:33 am Post subject:

PyQT4 ICEd in my setup.

xibo · Posted: Thu Aug 12, 2010 8:25 am Post subject:

Shining Arcanine · Veteran Joined: 24 Sep 2009 Posts: 1110

devsk · Posted: Thu Aug 12, 2010 7:24 pm Post subject:

ComaWhite · Tux's lil' helper Joined: 07 Oct 2008 Posts: 125

So far using -march=native -O2 -pipe on ~amd64 with GCC-4.5.1 everything works perfectly so far. except the latest version pf lvm2 refuses to compile just dropped back 1 version and it compiles. No issues from Mysql yet though I'm using 5.0.49 (i think).