linaro-toolchain

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Some initial notes on the effects of vldN and vstN vectorisation

by Richard Sandiford

I've now submitted the initial vldN and vstN work, so I thought I'd see how often it triggers for natty's libav package. I've put some initial results here: https://wiki.linaro.org/RichardSandiford/Sandbox/NeonLibAv There are more files to go through, so this isn't complete. I've also left out cases that were very similar to the ones given. Some of the code is reasonable, while others are obviously not as good as they could be. I don't think the problems are really to do with the vldN and vstN work itself though. They seem to be due to the underlying interleaved load/store detection, or in the handling of widening operations. Richard

15 years, 2 months

[ACTIVITY] 2011-04-15

by David Gilbert

== Bug triaging == * Bug 745843 (vtk ftbfs) got it down to a bad arm/thumb transition - identified as a linker error and handed off to RichardS * Bug 758082 (augeas ftbfs) tracked it down to overwrite of a parameter in a variadic function before it got stacked; identified by Ramana as another instance of the shrink-wrap bug. * Bug 745861 (petsc ftbfs) isolated the collection of different mpi related problems this is hitting; really need to find an mpi expert on this * Bug 745863 & bug 745891 (ftbfs's) - both were compilations that timed out; verified this was due to using lots of RAM and also using lots of RAM on x86 (> ~500MB) - marked as invalid until the build farm grows more RAM * Bug 757427 gconf seg fault - failed to reproduce under various tests (although Michael has now managed to catch it in the act) == Optimisation == * neon memcpy tweeking; added prefetches and unrolled the core loop - now comparable perf to bionic memcpy in most cases (slower on misaligned destination, faster in other cases) * tweaked latrace to print address/length of argument strings so I can get some stats on routine usage. Dave

15 years, 2 months

[ACTIVITY] Weekly status

by Richard Sandiford

== This week == * Worked on a fix for https://bugs.launchpad.net/gcc-linaro/+bug/758082 Submitted the patch upstream. * Finished first cut of vldN and vstN vectorisation. Send the patches upstream. Most of the patches have been approved, but I'll wait for the others before committing. * Looked at how the vectoriser handles natty's libav. Found some nice loops, some OK-but-could-do-better, and some really atrocious. Wrote up the results here: https://wiki.linaro.org/RichardSandiford/Sandbox/NeonLibAv * Started writing micro benchmarks for each loop on that page. I'm about half way through now (starting from the bottom). * Started looking at whether the changes affect DENbench. * Patch review. * Wrote a small follow-up to the fix for LP 758082. * Some patch pinging. == Next week == * More micro benchmarks. * More DENbench. * Submit a merge request for the intrinsics improvements, if the remaining patches are approved. * Look at the poorer libav loops in more detail. Richard

15 years, 2 months

[ACTIVITY] report week 15

by Peter Maydell

RAG: Red: Amber: Green: now only 6 "core ARM emulation" patches in qemu-linaro not yet upstreamed (still lots of omap3 patches, though) Current Milestones: | Planned | Estimate | Actual | qemu-linaro 2011-04 | 2011-04-21 | 2011-04-21 | | Historical Milestones: finish qemu-cont-integration | 2011-01-25 | 2011-01-25 | handed off | first qemu-linaro release | 2011-02-08 | 2011-02-08 | 2011-02-08 | qemu-linaro 2011-03 | 2011-03-08 | 2011-03-08 | 2011-03-08 | == maintain-beagle-models == * some early prep for next week's qemu-linaro release == merge-correctness-fixes == * patch to fix Neon UNDEFs sent upstream and committed * patch fixing an overflow in signed VABAL.s32 upstreamed, committed * investigated a bug report which turns out to be that if you try to single step over an instruction which UNDEFs using qemu's gdb stub we execute the insn at the UNDEF vector and stop after it rather than stopping at the UNDEF vector * some investigation of qemu mishandling of FP exception flag setting; putting this on hold though, as it really isn't very high priority * reviewed patches from Aurelien doing some general softfloat cleanup == other == * trying to nail down proposed QEMU work for next cycle; work-in-progress: https://wiki.linaro.org/PeterMaydell/Qemu1111 * two IRC interviews for QEMU Google Summer of Code student to do some work on upstreaming of the Android emulator device models * meetings: toolchain, standup, architecture Q&A, divisional update Current qemu patch status is tracked here: https://wiki.linaro.org/PeterMaydell/QemuPatchStatus Absences: Holiday: 22 Apr - 2 May 9-13 May: UDS, Budapest (maybe) 15-16 August: QEMU/KVM strand at LinuxCon NA, Vancouver [LinuxCon proper follows on 17-19th]

15 years, 2 months

CoreMark Status

by Chung-Lin Tang

Hi, I've just pushed a merge of the current upstream patches for resolving the CoreMark regressions. (https://code.launchpad.net/~cltang/gcc-linaro/coremark-part1) To give a quick benchmark of the current status, testing Linaro 4.5 before/after the merge of those two patches: Optimization options used were just plain '-O2 -mtune=cortex-a9', tested on one of our Pandaboards running Maverick; all numbers are Iterations/Sec averaged from 3 runs. r99492 r9942+patches improve % -march=armv5te 2786.87 2848.12 2.20 % -march=armv7-a 2474.50 2775.92 12.18 % -march=armv7-a -mthumb 2297.86 2356.59 2.56 % I'll have to re-test to be sure, but the numbers/improvements obtained using upstream trunk should not be too far off, at least the ARM mode ones. As we discussed in prior meetings, there's still one point of regression identified that's in solving, which hopefully will finally bring the ARMv7-A numbers above ARMv5TE. Chung-Lin

15 years, 2 months

[Activity] 10th - 14th April

by Revital Eres

Hello, - Tracking down bugs exposed while testing a patch for SMS to avoid using -fauto-inc-dec flag and preparing fixes for them. Also, prepared a fix for PR47013. - Continue looking into DENbench and updating https://wiki.linaro.org/Internal/ToolChain/Benchmarks. Thanks, Revital

15 years, 2 months

[Activity] 11th - 14th April

by Ramana Radhakrishnan

== GCC == Progress: * Spent some time digging into binutils issue for Neon but still not sure why I see the problem when this is fixed in 2.21 branch and no one else see this. * Fixed PR 48090 upstream. * Some patch review. * T2 performance meeting. Plans when I'm back: * Continue looking at divmodsi4 improvements. * Continue looking at excessive VFP moves. * Backport the fix for the initialization of cgraph into FSF 4.5 branch. Meetings: * 1-1s * Linaro toolchain meeting * T2 performance. * Linaro@UDS meeting. Absences: * April 15 – 26 -> Booked. * May 9-14 - LDS Budapest

15 years, 2 months

Issue with noreturn static function with unused arg

by Loïc Minier

hey This problem with busybox: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=621137 seems to be a toolchain issue. It occurs with FSF GCC 4.5.2 but not 4.6, and it doesn't occur with Linaro GCC 4.5 but it does with Debian gcc-4.5. I'm trying to identify the fix which Linaro applied to solve this! :-) Michael Hope told me he remembers we fixed something similar for Qt, but he couldn't find the patch and suggested I post here to get feedback. I've pushed ash.i and .s at: http://people.linaro.org/~lool/ash.i which you can build with: gcc -save-temps -std=gnu99 -Wall -Wshadow -Wwrite-strings -Wundef -Wstrict-prototypes -Wunused -Wunused-parameter -Wunused-function -Wunused-value -Wmissing-prototypes -Wmissing-declarations -Wdeclaration-after-statement -Wold-style-definition -fno-builtin-strlen -finline-limit=0 -fomit-frame-pointer -ffunction-sections -fdata-sections -fno-guess-branch-probability -funsigned-char -static-libgcc -falign-functions=1 -falign-jumps=1 -falign-labels=1 -falign-loops=1 -g -Os -c -o ash2.o ash.i the interesting part is that ash.s has tryexec as not returning, when it does return: grep ^tryexec ash.s -A5 | grep return this seems to be due to the combination of tryexec being static, its parent being noreturn, and one argument of tryexec being unused. Any idea of which Linaro patch solved this? :-) Does it make sense to raise this to FSF GCC 4.5? Thanks! -- Loïc Minier

15 years, 2 months

First toolchain estimate for the next cycle

by Michael Hope

Hi there. Mounir and I have been looking at the work for next cycle. A summary spreadsheet with notes is available here: https://spreadsheets0.google.com/ccc?key=ty1c-H56f0GxnL1Hk9LCmRg I'm very interested in feedback, especially on the time estimates and extra topics we should suggest to the TSC. See the notes at the top and feel free to add items or estimates straight into the sheet - anyone can view and anyone at Linaro should be able to edit. -- Michael

15 years, 2 months

Differences in build hosts

by Michael Hope

Hi there. I ran a build of gcc-linaro-4.5+bzr99491 on ursa1 through 4 to see if there was any difference in build machines. The following tests had different results: * gcc.c-torture/compile/limits-structnest.c * gcc.dg/graphite/block-4.c * largefile.c * obj-c++.dg/template-5.mm * obj-c++.dg/template-5.mm * obj-c++.dg/template-6.mm * obj-c++.dg/template-6.mm * objc/execute/class-4.m I suspect that they're all caused by running the testsuite in parallel and the host running out of memory. limits-structnest takes around 850 MB of RAM and passes on the machine with swap (ursa1) and fails on the others. block-4.c takes 2:35 to run and timed out on ursa1 and passed on the others which may be due to ursa1 swapping heavily while running a limit test in parallel. The obj-c tests show various forms of killed, and suggest that they were killed due to another process taking all the memory. I'll change the machines to use the full 1 G of memory, run the test suite in sequential mode, and see how things go. I haven't investigated largefile.c - it's a PCH test and these fail randomly. Regarding block-4.c, it takes 155 s to run which is too close to the default 300 s for my taste. Should we add a dg-timeout-factor 4.0 to it similar to block-3.c? -- Michael

15 years, 2 months

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