Hello,
could you please provide some comments about the state of "-Os"
(optimising for size) in the gcc 4.5.x versions of Linaro's tool
chain?
It appears there are a number of issues with recent versions of GCC
that get triggered when optimising for size, for example
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45052http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44392
Some other projects like the Linux Foundation driven Poky (resp.
Yocto project) capitulated and stopped using -Os, see for example
here:
http://thread.gmane.org/gmane.linux.embedded.poky/2311/focus=2565
On the other hand, I can see that Linaro even adds improvements for
"-Os", see for example here:
http://thread.gmane.org/gmane.linux.linaro.toolchain/367
So I wonder what the state of these problems with "-Os" is in the
Linaro tool chain? Have these issues been solved, and is "-Os"
reliably working with the Linaro tool chain?
Thanks in advance.
Best regards,
Wolfgang Denk
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd(a)denx.de
The optimum committee has no members.
- Norman Augustine
I assume we're moving the toolchain calls over to the
new confcall numbers -- but just to check, are we doing
so for this Wednesday's status call? The calendar
entry still has the old numbers...
-- PMM
==GCC==
Progress:
* Got invited to the Toolchain WG and was at the sprint in Dallas.
* Worked on fixing inconsistencies in the A9 scheduler. Now fixed up
upstream and submitted merge request for that.
* Introduced to other members of the Toolchain WG and had
conversations with everyone about what was going on within the
Toolchain WG.
* Spent some time trying to set up a Pandaboard that I borrowed
(Thanks Wookey) but the Panda didn't work. Turns out both the SD cards
were broken and or the versions of the boot loader / firmware were
broken.
* Worked through the patch list with Andrew trying to understand the
patches that exist in the backend for the delta between gcc-linaro and
upstream.
* Did some patch review upstream to help ease the backlog.
* Flushed some patches out from my patch queue upstream.
* Fixed the scheduler issue upstream and submitted a merge request for
it in linaro gcc-4.5 since it really fixes the A9 scheduler.
* Some ARM internal tasks with respect to transition into Linaro.
* Worked on the divmodsi4 issue and testing my patch with trunk.
Pushed my branch into launchpad if someone wants to see the code. Does
the right thing for the case we want but won't help with the SPEC2k
case really because that's a case with Os. But a good size improvement
anyhow and something that will help with divmod cases with 2 variables
rather than where a constant is used.
* Set up a natty chroot on one of our ve2 boxes which is now running a
bootstrap for all languages we are interested in and collecting test
results from trunk upstream.
* Worked through the new starter guide and still have an issue with
accessing wiki.linaro.org
Absences:
February 1-3:ARM Internal engineering conference.
== GCC ==
* Analyzed root cause of #685352 (libplymouth2_0.8.2-2ubuntu6 and
later give ragged splash and text rendering), opened mainline
bugzilla PR rtl-optimization/47299
* Submitted backport merge request for the #685352 fix
* Successfully completed profiled-bootstrap run on ARM
* Investigated profiled pyhton package build problems
== GDB ==
* Forward-ported GDB patch to support ARM hardware watchpoints
* Determined root cause of #615978 (Failure to software single-step
into signal handler), started discussion of proposed fix
* Miscellaneous Launchpad bug maintenance
Mit freundlichen Gruessen / Best Regards
Ulrich Weigand
--
Dr. Ulrich Weigand | Phone: +49-7031/16-3727
STSM, GNU compiler and toolchain for Linux on System z and Cell/B.E.
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Martin Jetter | Geschäftsführung: Dirk
Wittkopp
Sitz der Gesellschaft: Böblingen | Registergericht: Amtsgericht
Stuttgart, HRB 243294
=A9 Qemu=
I've spent most of the week looking at QEmu emulation of SMP A9. The
model (of a realview-pbx-a9) doesn't have any working block IO;
I spent some time looking at trying to get SD working and got part
way, but I fell back to using NFS root.
It seems to work OK for basic CPU emulation, and SMP 'works' in the
sense that the guest sees multiple CPUs;
however QEmu is restricted to only using one host CPU core for
multiple guest CPUs, so it's of limited
help in debugging SMP code.
Video doesn't seem to work either.
To get to that point it does need a bunch of patches to QEmu, most of
which Peter Maydell already knows of;
I've put some notes here :
https://wiki.linaro.org/Internal/People/DaveGilbert/QEMUA9SMP
Note that the realview-pbx doesn't currently have a Linaro hardware
pack; I used a kernel from ARMs website
and a 2.6.37 I built myself.
=SPEC=
SPEC ref got quite a far way through on Canis (with half-duplex
ether), however 'lbm' failed when running
in ref mode (while having worked in test and train) giving a different
output; it takes quite a long time to fail.
= Perf =
I sent an updated version of my patch for perf's thumb annotation upstream.
and apparently we have a Panda on the way.
Dave
RAG:
Red:
Amber:
Green:
Current Milestones:
| Planned | Estimate | Actual |
finish qemu-cont-integration | 2010-01-25 | 2010-01-25 | handed off |
first qemu-linaro release | 2011-01-11 | 2011-01-11 | |
Historical Milestones:
finish virtio-system | 2010-08-27 | postponed | |
finish testing PCI patches | 2010-10-01 | 2010-10-22 | 2010-10-18 |
successful ARM qemu pull req | 2010-12-16 | 2010-12-16 | 2010-12-16 |
* submitted meego patch upstream to print instruction
boundaries in TCG op-level debug dumps:
http://patchwork.ozlabs.org/patch/79298/
* reviewed a couple of patches by Christophe Lyon from ST
which fix some problems with VMULL and friends
(together with a qemu-meego patch in the same area)
* lots of rebasing work to get a qemu-linaro tree into
shape. Mostly putting together my exploded set of
ARM patches from the meego tree with a rebased set
of omap patches. I have something which I think is about
right but I need to test it.
* patches submitted to qemu upstream:
+ add -version option to qemu-user:
http://patchwork.ozlabs.org/patch/79635/
+ fix writing default vector address in PL190:
http://patchwork.ozlabs.org/patch/79712/
+ print instruction boundaries in TCG op-level debug dumps:
http://patchwork.ozlabs.org/patch/79298/
Current qemu patch status is tracked here:
https://wiki.linaro.org/PeterMaydell/QemuPatchStatus
Absences:
17/18 March: QEMU Users Forum, Grenoble
Holiday: 22 Apr - 2 May
I had a few spare cycles this afternoon on my A9 board so I got it to
build and run 72 variants of CoreMark with the 2011.01 compiler. The
results are here:
https://wiki.linaro.org/MichaelHope/Sandbox/CoreMark1
I haven't looked deeply into it and the usual disclaimer about
benchmarks applies, but there's some interesting stuff there. The ARM
to Thumb-2 drop is more than expected. Tuning for Cortex-A9 generally
makes things worse.
-- Michael
Hi,
One of the things that came up in yesterday's chat was about ARM vs
Thumb2. If some folks are interested in a high level overview that
doesn't go into too many details with respect to the ISA that I know a
compiler writer will be interested in you could read this presentation
unless you've seen it. At the minute the canonical way of figuring out
more about Thumb2 is really to read the ARM-ARM.
https://wiki.ubuntu.com/Specs/M/ARMGeneralArchitectureOverview?action=Attac…
This was a presentation that Dave Rusling gave at the UDS in Belgium
last year, it roughly covers the architecture at a high level and
talks about Thumb2 vs ARM , why Thumb2 , the evolution of the ARM
architecture etc. It's not a lot of detail but quite a high level overview.
HTH
cheers
Ramana
Hi,
* finished SLP for reduction patch. The loop in DenBench that needs
this feature also requires support of load permutation. I am
considering to implement that too. I looked for other occasions that
need this feature, but only found loops that are not vectorizable. So,
I am not sure I'll proceed in this direction.
* looked into extract_even/odd and interleave_high/low implementation
on ARM as a backup plan for the case we don't have special load/store
support on time for the next release. Even though NEON VZIP and VUZP
instructions can perform both even and odd (and high and low)
computations simultaneously, I don't see how we can express that at
the tree level.
* looking into ffmpeg
* non-Linaro issues
Ira
Hi ,
So rather than manually backporting a patch from upstream "trunk" I
decided to try using bzr for this yesterday. Even though this was a
slow process and thanks to some help from Michael on IRC last night I
think I got it right finally. However I can't get bzr visualize to
show me the revision history correctly with the merge from the
upstream repository.
So what I did was to do the following
bzr branch 4.5 new-branch
cd new-branch
bzr merge -c XXX lp:gcc where XXX is the bzr revision number of the
svn commit that I'm tracking upstream.
gcc/Changelog merge fails - there is a conflict. Expected because you
are merging trunk's gcc/Changelog into a version of the Changelog file
in our tree
Thus I reverted changes that were brought in by copying in a backup of
gcc/Changelog that I had made before the merge
bzr resolved gcc/Changelog
edit Changelog.linaro
Add changelog entry
bzr commit
bzr push lp:gcc private repository
Create merge request upstream.
Does this look sensible to people or do folks follow other recipes?
cheers
Ramana
