GCC 4.1

rhill · Posted: Mon Jul 11, 2005 8:37 am Post subject: GCC 4.1

This thread is a continuation of the GCC 4.0 thread in Portage and Programming. GCC 4.1 hit stage 3 on July 8th, meaning that all the major projects have more or less been committed and the branch is open for regression fixes only.

GCC 4.1 is still very alpha software. It does contain major bugs, known and unknown, and will not give you a stable system. People who might be interested in using 4.1 now are people who want to help debug the compiler itself or developers who want to see how their code will work with future versions. If you decide to try out 4.1, expect that things will break badly and often, and you will need to fix them on your own. :wink:

Projects contributed in stage 1 and 2
New C Parser
LibAda GNATTools Branch
Code Sinking
Improved phi-opt
Structure Aliasing Part I
Autovectorization Enhancements
Hot and Cold Partitioning
SMS Improvements
Integrated Immediate Uses
Tree Optimizer Cleanups
Variable-argument Optimization
Redesigned VEC API
IPA Infrastructure
Altivec Rewrite
Warning Message Control
New SSA Operand Cache Implementation
Structure Aliasing Part II
Safe Builtins
Reimplementation of IBM Pro Police Stack Detector (-fstack-protector)
New DECL hierarchy
Compilation Level Analysis of Types and Static Variables

Known regressions
http://gcc.gnu.org/wiki/Regressions

Helpful Links
GCC Wiki - http://gcc.gnu.org/wiki/
GCC Development Manual - http://gcc.gnu.org/onlinedocs/gcc/
GCC Development Internals Documentation - http://gcc.gnu.org/onlinedocs/gccint/
GCC Bugs Guide - http://gcc.gnu.org/bugs.html
Testing GCC - http://gcc.gnu.org/wiki/TestingGCC
Debugging GCC - http://gcc.gnu.org/wiki/DebuggingGCC
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neuron · Advocate Joined: 28 May 2002 Posts: 2371

guess we'll start seeing actual performance increases over the 3.4 series now, anyone have any numbers comparing gcc4 and 4.1?

scoobydu · Posted: Tue Jul 12, 2005 4:31 pm Post subject:

Whats the general opinion on support for gcc4.x?

Is it ready for a non techie to try?

I tried early 4 but without much success ..
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fuoco · Guru Joined: 23 May 2004 Posts: 386 Location: Israel

ProPolice is now integrated into vanilla gcc ? I suppose it works the same way with the same flags as with the patch ?

What's the difference between ProPolice and FORTIFY_SOURCE - or whatever it's called ?

aspenhydrowave · n00b Joined: 08 Dec 2004 Posts: 41

neuron · Advocate Joined: 28 May 2002 Posts: 2371

luisfelipe · Guru Joined: 09 Apr 2005 Posts: 377

Can I install gcc 4.1 on another slot and use it ??
From what I recall this wasn't possible before due to some conflicts with glibc I guess.

If I want to use gcc 4.1, can I just install it and keep changing it with gcc-config ?

neuron · Advocate Joined: 28 May 2002 Posts: 2371

luisfelipe · Guru Joined: 09 Apr 2005 Posts: 377

I tought I read it somewhere that it wasn't working, but the GCC 4.x threads are so big I can't
find it again

Well, just finishing compiling kdelibs, gonna try to install that later and see how it goes.

luisfelipe · Guru Joined: 09 Apr 2005 Posts: 377

Well, I'm trying to install it, and I'm getting this error :

/var/tmp/portage/gcc-4.1.0_beta20050709/work/gcc-4.1-20050709/gcc/tree-ssa-live.c: In function 'build_tree_conflict_graph':
/var/tmp/portage/gcc-4.1.0_beta20050709/work/gcc-4.1-20050709/gcc/tree-ssa-live.c:1463: error: corrupted profile info: number of executions for edge 97-121 thought to be 6280
/var/tmp/portage/gcc-4.1.0_beta20050709/work/gcc-4.1-20050709/gcc/tree-ssa-live.c:1463: error: corrupted profile info: number of executions for edge 97-98 thought to be -3705
/var/tmp/portage/gcc-4.1.0_beta20050709/work/gcc-4.1-20050709/gcc/tree-ssa-live.c:1463: error: corrupted profile info: number of executions for edge 147-143 thought to be -2308
/var/tmp/portage/gcc-4.1.0_beta20050709/work/gcc-4.1-20050709/gcc/tree-ssa-live.c:1463: error: corrupted profile info: number of executions for edge 147-148 thought to be 3592
/var/tmp/portage/gcc-4.1.0_beta20050709/work/gcc-4.1-20050709/gcc/tree-ssa-live.c:1463: error: corrupted profile info: number of executions for edge 149-147 thought to be -1291
/var/tmp/portage/gcc-4.1.0_beta20050709/work/gcc-4.1-20050709/gcc/tree-ssa-live.c:1463: error: corrupted profile info: number of executions for edge 149-150 thought to be 9503
make[2]: *** [tree-ssa-live.o] Error 1
make[2]: Leaving directory `/var/tmp/portage/gcc-4.1.0_beta20050709/work/build/gcc'
make[1]: *** [stagefeedback_build] Error 2
make[1]: Leaving directory `/var/tmp/portage/gcc-4.1.0_beta20050709/work/build/gcc'
make: *** [profiledbootstrap] Error 2

!!! ERROR: sys-devel/gcc-4.1.0_beta20050709 failed.
!!! Function gcc_do_make, Line 1211, Exitcode 2

thersites · Posted: Wed Jul 13, 2005 11:58 am Post subject:

I've been running a gcc-4.1 built system since 20050502.
With binutils-2.16.91.0.1 mozilla-firefox, the last package that was broken with gcc-4.1, sucessfully builds and runs.
However, still, if binutils is built with -O1, the gcc build fails.

So my CFLAGS ...

scoobydu · Posted: Wed Jul 13, 2005 12:32 pm Post subject:

Gestalt73 · n00b Joined: 02 Jun 2004 Posts: 29

UPDATE: Relaxed my CFLAGS to "-01 -march=athlon-xp -pipe" and was able to compete the compile.

The compile failed with my "agressive" flags: "-O3 -march=athlon-xp -fomit-frame-pointer -pipe -ffast-math"
Still a bit early for those I suppose.

Tried twice compiling with GCC 4.0.1 and GCC 3.4.3 and the compile fails here:

rhill · Posted: Sat Jul 16, 2005 5:35 am Post subject:

A couple automated benchmarks:
http://www.inf.u-szeged.hu/csibe/
http://people.redhat.com/dnovillo/spec2000/gcc/individual-run-ratio.html

For those having trouble compiling GCC, it could be the snapshot was taken at a time the tree was broken. You could try another snapshot or pull the code from CVS. Instructions are linked to on the GCC home page.
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m0p · Apprentice Joined: 20 Jun 2005 Posts: 205 Location: en_GB

I am going to install gcc 4.1 to test certain apps, so, before I emerged it, I ran it with -p to see what dependencies it would need. It seems it needs a new binutils. Would I need to use this new binutils for executing apps generated by the new gcc, or only for compiling them, or, is it neccesary to use the new one at all?

voidengineer · n00b Joined: 11 Feb 2005 Posts: 54

rhill · Posted: Sun Jul 17, 2005 12:08 pm Post subject:

pgrdsl

I'm trying to work out what has changed between the 4.0* family and 4.1* with regards to the ebuild/installation process.

My installation of 4.1-beta20050709 has some things installed in /usr/lib/gcc/i686-pc-linux-gnu/4.1.0-beta20050709 and some in /usr/lib/gcc/i686-pc-linux-gnu/4.1.0.
Unfortunately, the stuff in 4.1.0 are things like: fixincludes'd headers and libstdc++, and gcc-config is helpfully suggesting that binaries and libraries are in the other one.
Yes, I can frig things to get things to work, but this split installation directory doesn't seem right to me.

I raised this on the gcc bugs and got an immediate response of: --enable-version-specific-runtime-libs overrides all the other directories listed in configure.
Which is fair enough, and what the makefiles say - so why is --enable-version-specific-runtime-libs there?

Anyway, I'm intrigued: how come other people's 4.1 installs are working?
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m0p · Apprentice Joined: 20 Jun 2005 Posts: 205 Location: en_GB

According to "emerge -p =gcc-4.1.0_beta20050709", the new binutils won't install into another slot, it just upgrades, is there any bugs in the newer binutils?

EDIT: And which binutils should I install out of this list:

rhill · Posted: Sun Jul 17, 2005 4:29 pm Post subject:

did you add multislot to your USE flags in make.conf? if you did, try just emerge -pv binutils and see if that comes up as a slotted install.

any of those is fine. i have them all installed. ;P 2.16.1 is the latest testing version and fixes some bugs that were in 2.16, so maybe that would be the one to start with.
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m0p · Apprentice Joined: 20 Jun 2005 Posts: 205 Location: en_GB

Yes, I have multislot, but emerge -pv still doesnt say about creating a new slot.

m0p · Apprentice Joined: 20 Jun 2005 Posts: 205 Location: en_GB

Oh, got it installed now. I have run gcc-config as root, and ran env-update && source /etc/profile but gcc --version still says 3.4.4, but if I run as root it says 4.1.0. What is wrong?

Edit: Woops, selected wrong profile! disregard this post.

irf2003 · Veteran Joined: 10 Sep 2003 Posts: 1078

@everyone, don't play with gcc-4.1 on a live system unless u do not mind it borking, play with it on a spare partition or in a chrooted environment. And while you are playing with it, take it easy with your compiler flags, -O1 in gcc-4.1 land, is beaucoup optimizations, which may or may not work, at the time of writing.
happy Gentooing

m0p · Apprentice Joined: 20 Jun 2005 Posts: 205 Location: en_GB

I am using gcc 4.1, for external use. I am not compiling anything in portage with it. For example, I am using it to build the nightly sources of Firefox and Thunderbird, but with no good results! Here is the output of the firefox startup script after compiling the latest nightly with 4.1, and a stripped down set of CFLAGS:

neuron · Advocate Joined: 28 May 2002 Posts: 2371

well nobody said it was stable yet, just that it's getting there