- linaro-toolchain - lists.linaro.org

Re: RFC: Saving and restoring the assembler state during assembly

by Richard Sandiford

Dave Martin <dave.martin(a)linaro.org> writes: > However, there's not really anything fundamentally > architecture-specific about this problem, and ideally the solution and > the directives should not be architecture-specific either. > One option which appeals to me is to have some directives which can > exist across all architectures, and do something analogous to what > .set push and ,set pop do on MIPS. FWIW, this sounds like a really good idea to me. I won't argue about the syntax (I have no particular preference). > I feel that the environment should also include global, > target-independent state such as the current macro mode (.altmacro > versus .noaltmacro) and current ELF section stack state, but not > symbols or macro definitions themselves. Sounds reasonable. To state the obvious, we'd have to make the existing target-dependent groupings (like .set push/pop on MIPS) work with this new scheme, but those directives musn't affect this extra target-independent information. So the new directives would interact with both the traditional .pushsection and the traditional target-dependent directives, even though those two features would otherwise remain independent. That is, .pushsection and .set push/pop operate on conceptually separate stacks whoses pushes and pops can be freely mixed. But .pushsection and the new directives would need to be strictly stacked; pops must have the same form as their corresponding pushes. Combinations of .set push/pop and the new directives would also need to be strictly stacked. Nothing a bit of code can't handle though. Richard

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RFC: Saving and restoring the assembler state during assembly

by Dave Martin

Hi all, On ARM, we've now hit the problem a few times of temporarily overriding the assembler state (or rather, not being able to do this reliably). For example, sometimes there's a need to assemble a few instructions for a different architecture version so we can optionally execute or skip them at run-time is not really possible at present. This sort of feature is especially useful in macros but can be useful elsewhere too. There seem to be some target-specific solutions to this problem already. MIPS has its "option stack", maintained by .set push and .set pop directives. From the documentation, it sounds like this saves/restores a somewhat comprehensive set of state, but doesn't make much syntactic sense on arches which use .set to define symbols (i.e., most arches). PowerPC also has .machine push and .machine pop, but those only act on one specific aspect of the assembler state, and therefore aren't as portable a concept. However, there's not really anything fundamentally architecture-specific about this problem, and ideally the solution and the directives should not be architecture-specific either. One option which appeals to me is to have some directives which can exist across all architectures, and do something analogous to what .set push and ,set pop do on MIPS. My names would be .pushenv and .popenv, but obviously, they can be named any way people like. (For now I'm stealing groff's "environment" terminology to refer to such saved and restored state -- hence "env". Again, the nomenclature is arbitrary.) These directives would save and restore a target-specific set of state, which the philosophy that anything that can reasonably be changed with a directive mid-file can also be saved and restored with .pushenv/.popenv. Effectively, .popenv would be equivalent to issuing the necessary set of assembler directives to restore the assembler state to whatever it was at the last .pushenv (including the state of the environment stack itself) I feel that the environment should also include global, target-independent state such as the current macro mode (.altmacro versus .noaltmacro) and current ELF section stack state, but not symbols or macro definitions themselves. Currently, neither the macro mode nor the behaviour of .previous is reliably restorable after being changed (unless I missed something). This can result in unexpected behaviour after a macro which switches sections or changes the macro mode. This seems unfortunate since on most arches there is no syntactic difference between a machine instruction and a macro invocation -- hence in the presence of macros, the only time you're really 100% certain what .previous will do is immediately after a .pushsection or .section directive (which obviously is not much use). Comments are welcome -- at the moment this is just a fuzzy idea for a feature which might prove useful. I haven't investigated the implementation implications -- maybe it could be built straightforwardly around the current MIPS directives. Cheers ---Dave

15 years

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[ACTIVITY] August 7-11

by Ira Rosen

Hi, * fixed PR 50014 and 50039 - to be backported to linaro-gcc * tested the patch to change the default vector size on NEON * found one test that fails with quad-words - gcc.c-torture/execute/mode-dependent-address.c. Debugging it with Ramana. * started looking into widening shifts Vacation plans: next week Monday and Wednesday and August 22 - 30. Ira

15 years

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ld in current (4.6-2011.07-0-8-2011-07-25_12-42-06) toolchain fails to link uboot

by Bernhard Rosenkranzer

Hi, ld in the current (4.6-2011.07-0-8-2011-07-25_12-42-06) Android toolchain fails to link uboot: arm-eabi-ld: /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/libgeneric.o: Unknown mandatory EABI object attribute 44 arm-eabi-ld: failed to merge target specific data of file /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/crc16.o arm-eabi-ld: /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/libgeneric.o: Unknown mandatory EABI object attribute 44 arm-eabi-ld: failed to merge target specific data of file /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/crc32.o arm-eabi-ld: /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/ctype.o: Unknown mandatory EABI object attribute 44 arm-eabi-ld: failed to merge target specific data of file /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/ctype.o arm-eabi-ld: /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/div64.o: Unknown mandatory EABI object attribute 44 arm-eabi-ld: failed to merge target specific data of file /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/div64.o arm-eabi-ld: /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/errno.o: Unknown mandatory EABI object attribute 44 arm-eabi-ld: failed to merge target specific data of file /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/errno.o arm-eabi-ld: /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/ldiv.o: Unknown mandatory EABI object attribute 44 arm-eabi-ld: failed to merge target specific data of file /mnt/user/bero/android-iMX53-20110716151649/out/target/product/iMX53/obj/u-boot/lib/ldiv.o I believe this is already fixed in upstream binutils (or at least in hjl's 2.21.52.0.2 release from kernel.org /pub/linux/devel/binutils). ttyl bero

15 years

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tomorrow's call cancelled.

by Ramana Radhakrishnan

Given I'm away at some internal training and we had one last week . I decided to cancel this. Ramana

15 years

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[ACTIVITY] report week 31

by Peter Maydell

RAG: Red: Amber: OMAP3 patch upstreaming is slower progress than hoped Green: Current Milestones: || || Planned || Estimate || Actual || ||qemu-linaro 2011-08 || 2011-08-18 || 2011-08-18 || || Historical Milestones: ||qemu-linaro 2011-04 || 2011-04-21 || 2011-04-21 || 2011-04-21 || ||qemu-linaro 2011-05 || 2011-05-19 || 2011-05-19 || n/a || ||close out 1105 blueprints || 2011-05-28 || 2011-05-28 || 2011-05-19 || ||complete 1111 planning || 2011-05-28 || 2011-05-28 || 2011-05-27 || ||qemu-linaro-2011-06 || 2011-06-16 || 2011-06-16 || 2011-06-16 || ||qemu-linaro-2011-07 || 2011-07-21 || 2011-07-21 || 2011-07-21 || == upstream-omap3-patches == * discussion with upstream about how best to model omap-gpmc as qdev == other == * Attended Linaro Connect Q3.11 * submitted some patches which fix minor bugs that were preventing the QEMU M3 model from booting the Keil example binary images * miscellaneous upstream patch review Current qemu patch status is tracked here: https://wiki.linaro.org/PeterMaydell/QemuPatchStatus Absences: 9, 10 August: manning Linaro demo stand at APM 15-19 August: KVM Forum and LinuxCon NA, Vancouver

15 years

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[ACTIVITY] Weekly status

by Richard Sandiford

== Last week (Linaro Connect) == * Reran libav comparisons after Ira's fix for excessive promotion. The vectorized versions are now at least as good as the non-vectorised ones. Updated wiki page with new asm output and microbenchmark results. * More work on SMS. I have some patches that wire up the ddg code to IV analysis. It gave some nice benchmark improvements, but also some regressions. Traced the regressions down to cases where the schedule for small iis generated too many moves. E.g. in a small microbenchmark, we were able to schedule 6 instructions with an ii of 3 (i.e. in a loop iteration of 3 cycles), but then needed to add ~9 moves in order to keep the dependencies correct. We got much better code with a larger ii and fewer moves. Wrote a patch to estimate how many moves would be added, and to try to a larger ii if the number of moves is too high. This improved the results for one benchmark independently of the iv patch, and had no effect on the others. Discussed this with Revital, who said that Mustafa had tried a similar thing but seen no benefit. * Got powerpc-ibm-aix5.3 bootstraps working. Needs a few local fixes due to C++ bootstrapping. Used it to test a couple of preparatory patches for the IV work. Submitted those patches upstream. * Ran benchmarks with -fno-schedule-insns after seeing that the first scheduling pass was responsible for the main NEON-vs.-non-NEON regression in EEMBC. It fixed that case, but as expected, made others worse. Mentioned this to Ramana, who pointed me at -fsched-pressure. Reran the benchmarks with -fsched-pressure instead of -fno-schedule-insns. It too fixed the main regression, and improved a couple of other tests too. It showed a regression in another test though. Looked at that regression. It was a case where many registers were live across a loop, but not used in it. This was causing the loop to have a very conservative schedule. It would be better to spill some of the other registers instead. Wrote a patch to take loops into account, and it seemed to do the right thing for EEMBC. Sent it to Andreas, after Ulrich mentioned that he had been looking at -fsched-pressure problems on s390. Andreas is away for a while, though, so I might put this on the back burner until he gets back. == This week == * SMS * auto inc/dec * libav, perhaps Richard

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[ACTIVITY] Aug 1-5

by Ira Rosen

Hi, * committed upstream a patch that reduces over-promotion of vector operations * started to work on a new version of the patch to change the default vector size for Neon * attended Linaro connect Ira

15 years

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[ACTIVITY] Weekly status

by Revital Eres

* Committed a set of SMS patches to trunk and gcc-linaro branch. * Implemented a hack to evaluate the potential of SMS on SPEC2006/libqauntum. * involved in non linaro issue

15 years

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[ACTIVITY] 2011-08-05

by David Gilbert

== QEMU == * After discussion with Peter started writing QEMU fixup for 64bit atomic helper version location. * Sent fixes for soc-dma code to qemu list * Trying to understand just how much of omap_dma's code is needed. == Other == * Travelling to/from connect * Wanted to dial into some of the seessions in Corpus and Magdelen rooms but the remote audio from them was unusable. Dave

15 years

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[ACTIVITY] weekly status

by Ken Werner

Hi, Libunwind: * finished initial ARM support for remote unwinding (libunwind-ptrace) Android: * took a closer look at the debuggerd * got the perflab benchmark running on my PandaBoard using Linaro GCC Misc: * remotely attended some Linaro Connect Android sessions Regards Ken

15 years

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[ACTIVITY] Aug 1 - Aug 5

by Ulrich Weigand

== GDB == * Created Linaro GDB 7.3 branch * Ported all remaining feature patches from Linaro GDB 7.2 * Backported mainline patches to fix remote test issues: - Fixed #804387 Shared library test problems - Fixed #804392 Rebuilt executables not copied - Fixed #804396 Spurious failures * Committed mainline patch to fix dlopen test cases for remote testing (#804387). * Committed mainline patches to fix misc. other remote test problems (#804396). == Misc == * Attended Linaro Connect in Cambourne. 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

15 years

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libav wiki page updated for current FSF trunk

by Richard Sandiford

I've updated: https://wiki.linaro.org/RichardSandiford/Sandbox/NeonLibAv so that it gives the output for current trunk, including Ira's commit yesterday to reduce the amount of overpromotion. I also reran the microbenchmarks. The good news is that the vectorised code is now better in all cases than the non-vectorised code. The biggest winner from last time was rgb24tobgr16_C(). It used to be much worse with vectorisation due to lots of excessive widening. Thanks to Ira's patch, the loop now looks pretty respectable, and is ~3.25x faster than the non-vectorised code. As well as using a more recent compiler, the new version also uses -mvectorize-with-neon-quad. Once again it shows a significant improvement over the default. Richard

15 years

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QEMU futures

by Michael Hope

Hi there. We had a brainstorm this afternoon about areas QEMU could go into in the future. My pigeon-scratchings are at: https://wiki.linaro.org/WorkingGroups/ToolChain/Q3.11/QEMUFutures See also: https://wiki.linaro.org/MichaelHope/Sandbox/RoadmapIdeas#QEMU_everywhere -- Michael

15 years

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[ACTIVITY] 25th - 31st July

by Andrew Stubbs

Continued work on widening multiplied. I've identified another cause for the bootstrap failure, and submitted the new version for testing. Continued trying to find out how my thumb2 constants patches are broken. This is taking ages due to the time it takes to turn around a bootstrap build on my IGEP board. Tried to get the CS Panda boards to work again. They'll do the bootstrap builds much faster (if still not quickly), but are no longer very well. All my attempts to bring them back up remotely have failed. I've discovered that the device the serial console on one was connected to has been relocated to the new Mentor Graphics board lab, so this might explain some of it .... Chaired the Monday and Thursday meetings in Michael's absence. Travelled to the Linaro Connect event in Cambourne, near Cambridge. Other: More machine trouble. I keep thinking I have the display issues solved, and then it starts up with all the windows displayed double sized, but requiring mouse clicks in the correct location .... typically this happened just when I needed access to the pin number for the Monday meeting. This hasn't happened since Monday, so hopefully it's now ironed out ... this sort of thing does not happen with Windows. :( ---- Upstream patched requiring review: * NEON scheduling patch http://gcc.gnu.org/ml/gcc-patches/2011-02/msg01431.html

15 years

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[ACTIVITY] Weekly status

by Revital Eres

* Looking into SMS patches sent to mainline which expands SMS functionally to avoid using doloop. The patches resolve the recent bootstrap failure on mainline. http://gcc.gnu.org/ml/gcc-patches/2011-07/msg01807.html * Continue looking into 462.libquantum.

15 years

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Using valgrind with linaro toolchain

by Diane Holt

Valgrind wants a less stripped ld-2.12.1.so or it won't work. The build process (that Michael Hope put together) just downloads the libc6_2.12.1-0ubuntu6_armel.deb, and the ld-2.12.1.so in there is fully stripped. I thought I'd be able to just get the libc6-dbg_2.12.1-0ubuntu6_armel.deb instead, thinking that was just the pre-stripped version of these libs -- but apparently it's not, because trying to use those libs instead of the stripped ones results in undefined symbols. For example, ld-2.12.1.so defines _rtld_global -- but libc-2.12.1.so is looking for _rtld_global@@GLIBC_PRIVATE, so _rtld_global@@GLIBC_PRIVATE ends up undefined. (Ditto for __tls_get_addr, __libc_enable_secure, _dl_argv, etc.) I'm not sure who actually builds these packages (they're retrieved from: http://ports.ubuntu.com/pool/main/e/eglibc/), but if anyone has any suggestions on how to get past this, I'd be most appreciative. (I've got angry developers trying to track down memory issues, who about to come after me with torches and pitchforks :P ) Thanks, Diane

15 years

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[ACTIVITY] Jul 25 - Jul 29

by Ulrich Weigand

== GDB == * Committed second mainline patch to fix re-built executable remote test problems (#804392). * Prepared for rebasing Linaro GDB on top of GDB 7.3 release. == Misc == * Prepared for Linaro Connect. 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

15 years

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[ACTIVITY] weekly status

by Ken Werner

Hi, * Monday was full of IBM internal meetings * Android * got a self built LEB and generic version 2.3.4 of linaro android running on my pandaboard (build with the gcc 4.6 07 release plus the patch that Richard made) * requires libicui18n.so (external/icu4c/i18n) to be built with -O2 * ran into a few issues (816491, 807230) * libunwind: * simplified the local unwinding (there is no need to touch the ARM exidx table segment when looking it up) * fixed a bug (corner case: the info of the IP to be unwound is described by the last unw entry) * made some progress on the remote unwinding via ptrace * remotely searching the unw withing entry exidx table segment * next step is to remotely extract the unw isns Regards Ken

15 years

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[ACTIVITY] report week 30

by Peter Maydell

RAG: Red: Amber: OMAP3 patch upstreaming is slower progress than hoped Green: various outstanding patches accepted upstream in time for 0.15 Current Milestones: || || Planned || Estimate || Actual || ||qemu-linaro 2011-08 || 2011-08-18 || 2011-08-18 || || Historical Milestones: ||qemu-linaro 2011-04 || 2011-04-21 || 2011-04-21 || 2011-04-21 || ||qemu-linaro 2011-05 || 2011-05-19 || 2011-05-19 || n/a || ||close out 1105 blueprints || 2011-05-28 || 2011-05-28 || 2011-05-19 || ||complete 1111 planning || 2011-05-28 || 2011-05-28 || 2011-05-27 || ||qemu-linaro-2011-06 || 2011-06-16 || 2011-06-16 || 2011-06-16 || ||qemu-linaro-2011-07 || 2011-07-21 || 2011-07-21 || 2011-07-21 || == upstream-omap3-patches == * omap-gpmc patches now all cleaned up; I think I need to look at qdevifying this device before submitting patches, though * sent patch for bug which makes n810 model crash when key is pressed * sent a pull request collecting together the patches submitted so far == other == * qemu 0.15: put together pull request for ARM patches I think should go into this release; wrote ARM-related bits of the release notes * helped GSoC student track down a bug causing android not to boot * LP:816791: tracking down issues with running mono under qemu (combination of a couple of known qemu bugs and a mono bug) * admin/prep for upcoming travel (cambourne, vancouver, orlando) * reviewing pl041 patches which add audio support to versatilepb and vexpress models * mailing list discussion of possible new qemu object model * lots of meetings this week (toolchain, standup, doughnuts, team comms x2) Current qemu patch status is tracked here: https://wiki.linaro.org/PeterMaydell/QemuPatchStatus Absences: 1-5 August: Linaro sprint 1111 15-19 August: KVM Forum and LinuxCon NA, Vancouver

15 years

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multilib'd (softfp/hardfp) gcc available in Ubuntu oneiric

by Matthias Klose

the current gcc-4.6/eglibc is now built multilib'd for -mfloat-abi=softfp|hard, including the GCC runtime libraries. I hope that the gcc cross builds will pick this up soonish, not needing to build the cross compiler twice for softfp and hard float-abi. Matthias

15 years

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[ACTIVITY] 2011-07-29

by David Gilbert

== 64 bit atomics == * Sent updated set of 64bit atomic patches to gcc list with fixes from previous review * Started hunting for other users of 64bit atomics than membase jemalloc, sdl and boost lock free look like possibilities; but I've not looked at them hard yet == QEmu == * Released fix for last SD card block access error - Vincent Palatin released a bunch of SD card fixes a few hours later - that included a fix to the same bug; however it does look like he has a bunch of other stuff we should keep sync'd with. * Changing caching mode to writeback on the block layer fixes bug 732223 (hangs on heavy IO) - goes from 130KB/s to 8MB/s on vexpress - Asked mailing list whether that's reasonable to make as default for SD * Looking at path from CPU->MMC/SD card - the DMA on OMAP is pretty inefficiently emulated, but the soc_dma code has an unused special case for dma'ing to hardware, looks promising but need to figure out how to use it and if it works. * Comparing Vincent's SD card patch with earlier meego patches; partial overlap. == Other == * Pinged libc-ports for comments on my optimised memchr patch * Image testing Next week; I intend to be in Camborne on the afternoon of Monday, Wednesday and Friday. Dave

15 years

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[ACTIVITY] July 24-28

by Ira Rosen

Hi, I am checking the coverage of the NEON instructions mostly by writing tests in C to check which instructions are generated (after auto-vectorization) and which are not. I put here https://wiki.linaro.org/IraRosen/Sandbox/InstructionCoverage the list of things that I've checked till now. Ira

15 years

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[ACTIVITY] 18th - 22nd July

by Andrew Stubbs

Spun release tarballs for Linaro GCC 4.5 and 4.6. Sent them to Michael Hope and Matthias Klose. Testing for my widening multiplies patches revealed a bug when the accumulate value had a different type. The problem is easily fixed, so I've created a patch, submitted it, and now it's approved upstream. Same again, this time with a bug involving constant integers. Again, easily fixed, submitted, and approved. Nobody had reviewed the first patch in my series - Richard Guenther had reviewed all the others, but wasn't happy to review the expand pass. So, I asked newly crowned RTL Maintainer Richard Sandiford to review it, but apparently it's the wrong bit of the back-end, so I asked Bernd instead. Bernd kindly reviewed and approved it, so now the whole series is ready to commit if only my test comes back clean. Continued trying to figure out why my thumb2 constants patch is broken. So far, no further progress. It might be that Michael's build system is confused, but it's looking likely to be a real bug. ---- Upstream patched requiring review: * NEON scheduling patch http://gcc.gnu.org/ml/gcc-patches/2011-02/msg01431.html

15 years

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[ACTIVITY] Weekly status

by Revital Eres

- Opened PR49789 to record the bootstrap failure with SMS flags. - SPEC2006/libquantum: Wrote a hack to apply SMS on the hot loop. Need to make it more accurate. - Pinged SMS patches in mainline. - Looking with Ramana on the effect of the Tree reassociation improvement patch on bwaves http://gcc.gnu.org/ml/gcc-patches/2011-07/msg00904.html

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