Hi,
* implemented reduction support in SLP, I'll check if it helps
DenBench next week
* helping Sebastian Pop with if-conversion for vectorization
improvements (BTW, Sebastian's goal is to vectorize kernels from
ffmpeg)
* fixed GCC PR47139
Ira
Hi All,
Thanks for attending the call. I think we had some interesting discussions.
I've posted the minutes from the call on the same page as before:
https://wiki.linaro.org/AndrewStubbs/Sandbox/GCCoptimizations
I'll try to get the audio posted somewhere for anybody that's interested.
Andrew
You may have noticed that I have created a new BZR/Launchpad branch for
Linaro GCC 4.6:
lp:gcc-linaro/4.6
https://code.launchpad.net/~linaro-toolchain-dev/gcc-linaro/4.6
Up until now, this has not been buildable due to unfixed bugs. However,
upstream GCC have now straightened out the problems, so I have pushed a
buildable version into the branch.
I shall attempt to keep this branch as up-to-date as I can (at least, I
will once the holiday season and January travel are over), but I'll only
push updates if they build for me, so hopefully the branch should remain
fairly stable, at least for our purposes.
Note that so far I've only tested build-ability. Right now I'm not
making any promises about the quality of the compiler.
At some point, we'll want to use this branch to hold our own patches
(both those that will never go upstream, and those that are queued for
GCC 4.7), so it will diverge from upstream 4.6 a bit. For the moment,
it's merely a mirror.
Andrew
== Last Week ==
* Got a new ARM-specific unwind test case working, so its integration
with libunwind stands a marginally better chance of working (once it's
finally finished).
* Sent a ping to binutils mailing list about a patch to improve readelf
that I had sent in at the beginning of December. Still no response.
* Holidays and Vacation
== This Week ==
* Try to finish libunwind integration, as my time with Linaro is nearly
over. Update documentation on wiki to reflect current status.
* Ping ltrace list about a new release. It seemed so close, then the
list went abruptly silent.
--
Zach Welch
CodeSourcery
zwelch(a)codesourcery.com
(650) 331-3385 x743
== Linaro GCC ==
* Continued looking at element/structure load/store intrinsics
improvements. Some good initial results: it looks like the plan of
using "extra-wide" vectors for returning struct results works fine (at
least to a first approximation). Sent off WIP patch (internally to CS
only, so far).
Incidentally this looks like it'll be a good stepping-stone for the
"RTL half" (vs. the "tree half") of the representation of
element/structure loads/stores (e.g. vld2/vst2) also. The return type
(for loads) and argument type (for stores) of the RTL patterns for such
instructions is changed from the current wide-integer representation
(OImode, etc.) to a suitable wide vector instead (e.g. V16QImode). This
change might help lead to a more meaningful mapping from an equivalent
tree form -- though we haven't quite got the whole picture yet, as the
middle-end won't want to know about the ARM-specific and
non-standard-named patterns for the element/structure loads/stores.
(One might imagine a new standard-named RTL expander taking care of that
though.)
== Vacation ==
* Vacation Dec 20th-Jan 4th.
== GCC issues ==
* PR44557, Thumb-1 ICE, looked at the ARM specific secondary reload
parts, as well as some general reload internals context. Concluded that
concerns on Thumb-2 about my submitted patch should be unneeded, as the
reload_in/out patterns should never be used for Thumb-2. Also looked a
bit on how we should upgrade ARM to use TARGET_SECONDARY_RELOAD.
* PR45416, ARM code regression. Started working on this again, cleaning
up patch to submit.
* Had some email discussion with Revital Eres on Swing Modulo Scheduling
(SMS) for ARM issues, mainly on how the doloop_end pattern should be
done on ARM.
* Submitted and committed an obvious small patch for a VFP testsuite case.
== This week ==
* Continue on GCC issues.
* Flying to Dallas on Sunday, prepare for trip.
Hi,
* continued with my attempts to vectorize Viterbi:
- finished implementation of conditional store sinking in cselim
pass (I did only limited testing).
- reconsidered the idea of safe load if-conversion if an adjacent
field of the same structure is accessed unconditionally - this may be
incorrect. Instead I tried the last, not yet committed, patch by
Sebastian Pop that implements if-conversion for such cases of not-safe
data accesses. His patch if-converts the loop in Viterbi, however, it
also makes the loop not vectorizable - additional work should be done
in the data-refs analysis and the vectorizer to make it work.
Sebastian is working on the first part, and I'll help him with the
vectorizer part if necessary.
* analyzed EEMBC DenBench, couldn't find any action items for now. But
vld/vst support of strided data accesses should be very useful for
these benchmarks.
* fixed GCC PR testsuite/47057
* looking into SLP of reduction as in PR 41881. I saw similar patterns
several times in DenBench, but I'm not sure that SLP of reduction is
enough to vectorize all of these cases.
Happy New Year,
Ira
== Last Week ==
* Continue with libunwind. Wrote a new unit test for ARM-specific
unwinding code to help debug that new code's problems. Almost got it
working, which I hope means its integration with libunwind may be
nearing completion.
== This Week ==
* Try to finish ARM-specific improvements to libunwind. Famous Last Words.
--
Zach Welch
CodeSourcery
zwelch(a)codesourcery.com
(650) 331-3385 x743
== GCC related ==
* Launchpad #693686, GCC ARM segfault ICE when building Chromium in V8.
Spent some time reproducing; this ICE seems to be in the maverick
gcc-4.5, at the vectorizer phase. As the ICE happens in
tree-vect-stmts.c:supportable_widening_operation(), I'm suspecting
(without further verification yet) this might be due to vmovn not
backported? (Linaro 4.5 does has this ported I think)
* PR44557, Thumb-1 ICE. Looking further after seeing Richard Earnshaw's
comment on my patch. It would be nice if we could upgrade the entire
secondary reload bits, looking into this.
== This week ==
* Look into more GCC issues.
* Get some backports done.
== Linaro GDB ==
* LP:615972
Get patch approved upstreams. Committed to FSF tree. Propose merge
request to Linaro GDB tree.
* LP:616003 gdb.mi/mi-var-display.exp failure
Discussed in upstreams on how to handle fp in ARM/Thumb mode. Finally
work out a one-line patch. Approved and committed to FSF tree. Propose
merge request to Linaro GDB tree.
Draft another patch to clean up ARM register alias. Pending on upstreams.
* LP:616000 Handle -fstack-protector prologue code
Revise patch per Joel's comments. Approved, and committed to FSF tree.
Draft two patches to handle -fstack-protector prologue code on i386.
Sent them out for review. Due to lack of knowledge on i386 prologue
generate, not very confident on one of these patches.
* LP:615980 Support displaced stepping on Thumb
Get my test case to arm displaced stepping approved, and committed to
FSF tree.
A patch about supporting displace ARM insn in Thumb area is pending
upstreams. Tried the 2nd approach since the 1st approach is not
acceptable to upstreams reviewers. Without this patch, ARM displaced
stepping doesn't work on Linaro.
Support another three PC-related 16-bit Thumb insns (adr, ldr, and
cbz), and add test cases for them accordingly.
Spend some time splitting my big patch into three relatively small
patches in order to make them easier to be reviewed. Patches on
supporting Thumb 16-bit displaced stepping are sent out upstreams for
review.
== This Week ==
* Work from Mon. to Wed.
** Backport some approved upstreams patches to Linaro GDB
** Anything I should do for my pending patches.
* Vacation on Thu. and Fri. 3rd Jan. is China public holiday. Back to
work on 4th. Jan.
--
Yao (齐尧)
