Hi all,
First sorry for the long message, but I am kinda stuck on an issue
with my split-stack work for aarch64, so any new eyes to check if
I am doing things properly would be really helpful.
I pushed my current work on a local gcc git [1] and glibc [2] branches.
The current code show not issue with the placed C tests, but there
is one elusive GO tests that fails for some reason.
The glibc patch is pretty simple: it adds a tcbhead_t field
(__private_ss) which will be used to hold the split stack thread
value. Different from stack protector, split-stack requires
a pointer per thread and it is used frequently on *every* function
prologue. So faster access is through TCB direct access (one
instruction less than TLS initial-exec). I plan to digress a little
more about why I decided to use TCB access, but in a short the advantages
are:
1. It is faster than TLS initial-exec
2. Does not require any static or dynamic relocation
The rest of patch is just to add a versioned symbol so either static
or dynamic linking fails for an older glibc (to prevent split-stack
binaries to run on non-supported glibcs).
The GCC patch is more complex, but it follows the already implemented
split-stack support on other architectures (x86, powerpc64, s390).
Basically you add hooks to generate the required prologue and other
bits (C varargs requires some work) and add some runtime support on
libgcc (morestack.S).
Split-stack idea is basically as this: let say you have a function
that requires a very large stack allocation that might fail at
runtime (due ulimit -s limit). Split-stack add some instrumentation
that check if the stack allocation will fail based on initial
value and allocates stack segments as required.
So basically a function would be instrumented as:
function foo
ss := TCB::__private_ss
if SP + stack_allocation_size > ss
call __morestack
// function code
What __morestack basically does is create a new stack segment with
some slack (using a platform neutral code), change the stack pointer
and continue run the function. So a stack frame for a function
that called __morestack is as:
foo
\_ __morestack
\_ // function code
And when the function code finished its execution (including all
possible function calls), it returns to __morestack so it restore
the old stack pointer and arguments.
Now, this is the most straightforward usage of __morestack. However
GO language allows a construct [3] that allows a function to register
a callback that is called at end of its scope that allows to 'recover'
from some runtime execution failure.
And this is the remaining GO tests that fails [4]. What it basically
does is run a set of tests that allocate some different structure and
try to access it in different invalid way to check if accessing a
know null pointer is caught by the runtime (GO adds null pointer checks
for some constructs).
9 func main() {
10 ok := true
11 for _, tt := range tests {
12 func() {
13 defer func() {
14 if err := recover(); err == nil {
15 println(tt.name, "did not panic")
16 ok = false
17 }
18 }()
19 tt.fn()
20 }()
21 }
22 if !ok {
23 println("BUG")
24 }
25 }
41 var tests = []struct{
42 name string
43 fn func()
44 }{
76 {"*bigstructp", func() { use(*bigstructp) }},
108 type BigStruct struct {
109 i int
110 j float64
111 k string
112 x [128<<20]byte
113 l []byte
114 }
So basically here it tries to allocate a very big structure (BigStruct with
about 128 MBs) on stack and since it does not have stack allocation it will
need to call __morestack.
Now, if have patient to read until now, the way GCCGO does that is by
throwing an exception to unwind the stack and to add some CFI directives in
both generated code and morestack to correct handling the unwinding.
So if GCC generates the unwind information for the objects and if __morestack
have the correct unwind information it should, so I presume my patch is
failing in either define the correct exception handler directives in
morestack.S or I am failing in generate the correct __morestack call.
The __morestack call is done at 'aarch64_expand_split_stack_prologue' in
my patch as:
--
+ /* Call __morestack with a non-standard call procedure: x10 will hold
+ the requested stack pointer and x11 the required stack size to be
+ copied. */
+ args_size = crtl->args.size >= 0 ? crtl->args.size : 0;
+ reg11 = gen_rtx_REG (DImode, R11_REGNUM);
+ emit_move_insn (reg11, GEN_INT (args_size));
+ use_reg (&call_fusage, reg11);
+
+ /* Set up a minimum frame pointer to call __morestack. The SP is not
+ save on x29 prior so in __morestack x29 points to the called SP. */
+ aarch64_pushwb_pair_reg (DImode, R29_REGNUM, R30_REGNUM, 16);
+
+ insn = emit_call_insn (gen_call (gen_rtx_MEM (DImode, morestack_ref),
+ const0_rtx, const0_rtx));
+ add_function_usage_to (insn, call_fusage);
+
+ reg29 = gen_rtx_REG (Pmode, R29_REGNUM);
+ cfi_ops = alloc_reg_note (REG_CFA_RESTORE, reg29, cfi_ops);
+ reg30 = gen_rtx_REG (Pmode, R30_REGNUM);
+ cfi_ops = alloc_reg_note (REG_CFA_RESTORE, reg30, cfi_ops);
+ insn = emit_insn (aarch64_gen_loadwb_pair (DImode, stack_pointer_rtx,
+ reg29, reg30, 16));
+
+ /* Reset the CFA to be SP + FRAME_SIZE. */
+ new_cfa = stack_pointer_rtx;
+ cfi_ops = alloc_reg_note (REG_CFA_DEF_CFA, new_cfa, cfi_ops);
+ REG_NOTES (insn) = cfi_ops;
+ RTX_FRAME_RELATED_P (insn) = 1;
+
+ emit_use (gen_rtx_REG (DImode, LR_REGNUM));
+
+ emit_insn (gen_split_stack_return ());
--
I do not add any stack frame allocation for the call, so it might a source
of issues.
Another issue might in morestack.S unwinding directives that is not following
the ABI correctly. I am revising it using GCC generated exceptions examples.
[1] https://git.linaro.org/toolchain/gcc.git/shortlog/refs/heads/linaro-local/a…
[2] https://git.linaro.org/toolchain/glibc.git/shortlog/refs/heads/azanella/spl…
[3] https://blog.golang.org/defer-panic-and-recover
[4] gcc/testsuite/go.test/test/nilptr2.go
=== This Week ===
Support for watchpoint un-alligned watchpoint addresses on LLDB
AArch64 [TCWG-367] [3/10]
-- Implementation successful without the need for instruction emulation.
-- Watchpoint hit detection fixed with ptrace reporting hit address correctly.
-- Used up watchpoint HitAddress function to return back the real
address to host.
Investigation of Nexus devices kernel issues.[TCWG-622] [2/10]
-- Figured out steps to build custom kernel for Neuxs7.
-- Kernel fails to boot though.
LLDB hardware watchpoint capability test and skip watchpoint testing
[TCWG-622] [2/10]
-- Submitted a patch to report back correct reason for watchpoint
creation failure.
Miscellaneous [3/10]
-- Meetings, emails, discussions etc.
-- A look into LLDB xfail decorators to fail on the basis of arm ABI.
-- Out of office on Thursday 9th June for visa interview.
=== Next Week ===
Support for watchpoint un-alligned watchpoint addresses on LLDB
AArch64 [TCWG-367]
-- Finish up work, test and submit for review upstream.
LLDB hardware watchpoint capability test and skip watchpoint testing [TCWG-622]
-- Patch review and further progress.
Miscellaneous
-- Testsuite Makefile.rulez update still pending, hopefully will be
done this week.
-- Xfail decorator updates to xfail based on ARM ABI.
=== This Week ===
Investigation of Nexus devices kernel issues.[TCWG-622] [6/10]
-- Figured out source trees for various android devices and checked
out kernel code.
-- Comparison between watchpoint implementation of different kerenel
sources supported by Nexus devices.
-- Figured a way to burn a custom rom with updated kernel on Nexus 7.
-- Figured Kconfig issue that was causing watchpoints not to be
detected on Nexus 7.
-- Watchpoint installation still doesnt work on Nexus 7.
LLDB buildbot updates and maintenance [TCWG-241] [2/10]
-- Upgraded cmake version after migration to new version.
-- Migrating local buildbot setup (builders and testers) to ubuntu xenial 16.04
-- Buildbot restart after power outage.
Miscellaneous [2/10]
-- Meetings, emails, discussions etc.
-- Out of office on Tuesday 31st 2016 for visa documents preparation.
=== Next Week ===
Support for watchpoint un-alligned watchpoint addresses on LLDB
AArch64 [TCWG-367]
-- Continue work on hardware watchpoint support.
Investigation of Nexus devices kernel issues.[TCWG-622]
-- Figured out steps to build custom kernel for Neuxs7.
LLDB hardware watchpoint capability test and skip watchpoint testing [TCWG-622]
-- Investigate possible ways to solve this issue.
Miscellaneous
-- Out of office on Thursday 9th June for visa interview.
* One day off on Thu [2/10]
# Progress #
* TCWG-639, non-8-byte-aligned watchpoint is missed on aarch64. [4/10].
It is caused by limited kernel BAS support. RedHat reports this
problem and posts a patch. Good to see they start to contribute to
aarch64 GDB, but I don't like the patch. Spend much time writing a
prototype to prove their patch is not perfect. We agree to fix this
problem by extend RSP fortunately.
* TCWG-333, [3/10] I follow the way how mips does, and fix some bugs.
* TCWG-547, TCWG-518, blocked in upstream review.
* Misc, meetings. [1/10]
# Plan #
* TCWG-333, TCWG-556.
* Ping TCWG-547, TCWG-518.
--
Yao
== Progress ==
o Extended Validation (4/10)
- Investigate and reported Glibc/libsanitizer issue
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71445
- Looked at benchmark job issues
- Discuss benchmark/lava notification mechanism
o Linaro GCC (1/10)
- Merged FSF GCC 5.4 branch
o Upstream GCC (3/10)
- ARMv8.1 libatomic investigation:
seems to work fine when enabling multilib on AArch64
need to investigate completeness of the support.
o Misc (2/10)
* Various meetings and discussions.
* Backlfip patch reviews
== Plan ==
o Backport reviews and June snapshots
o Continue libatomic
o Benchmarking job fixes.
== This Week ==
* LTO (5/10)
a) committed r237207 to fix unresolved test-cases added in r236503 (1/10)
b) move increase_alignment pass to regular pass (3/10)
- Patch iterations based on suggestions from Honza and Richard
- Understanding lto streaming and decl merging code
c) TCWG-548 (1/10)
- WIP patch
* TCWG-319 (1/10)
- updated patch submitted upstream:
- changing vect_hw_misalign causes regression for vect-align-1.c
* Benchmarking (1/10)
- Benchmark successfully ran for linaro-gcc-5 submitted by Yvan
- Benchmark for fsf-gcc-6 failed both with prebuilt route and letting
job build the benchmark
* Misc (3/10)
- Meetings
- Travel to Mumbai for Schengen Visa appointment
== Next Week ==
- Try to get patch committed for increase_alignment
- TCWG-319: Look at vect-align-1.c regression
- TCWG-548: Complete implementation and validate patch.
- ipa-vrp: Experiment with Kugan's patch.
== Progress ==
* Validation
- disk full on one builder caused problem during the validation of
the long series of backports. We'll have to refine the cleanup policy.
- switch to docker on-hold until the builders are upgraded
* ABE
- looked a bit at the gdb/gdbserver issue
* Backports
- used a script to process the spreadsheet and submitted all the
backports that backflip was able to complete in batch mode (a lot!)
- fsf-5-branch merge review
* GCC
- regression reports on trunk, chasing problems that occur in corner
case configurations
- One of the Neon intrinsics tests I committed recently wrongly
executed v8 Neon code on v7 HW: I didn't catch this earlier because of
a bug in qemu, promptly fixed by Peter Maydell
- neon-testgen.ml removal delayed because other cleanup is desirable
before (fixing neon* effective-target tests on-going)
- started looking at PR 67591 (ARM v8 Thumb IT blocks deprecated)
* Support
- started looking at bug 2315
* Misc (conf-calls, meetings, emails, ...)
== Next ==
* Validation:
- patch reviews
- look at disk management/cleanup
* Backports
- check validation results
* GCC
- monitor trunk regressions
- fix "check_vect" guard in gcc.dg/vect tests
- fix neon* effective-target
- hopefully test-neongen.ml removal
- pr 67591
- advsimd tests
== Progress ==
TCWG-607 Initial ARM port for LLD committed upstream. Hello World on
an ARM with an ARM only gcc libc is possible, but not much else.
TCWG-611 Initial Thumb support sent for upstream review. Interworking
is possible at the BLX level but full interworking support
(veneers/thunks) isn't there yet. With this patch it will be possible
to do Hello World with a recent Linaro gcc release.
TCWG-634 llvm-mc putting out R_ARM_THM_PC24 for B<cond>.W instead of
R_ARM_THM_PC19. Simple fix now committed upstream.
== Plans ==
Interworking thunks for lld. The existing thunk design is very simple
and only supports one type of thunk per target. For interworking we
need at least two (ARM to Thumb) and (Thumb to ARM).
I think it might be possible to fit a basic implementation just good
enough for ARMv7a to be correct into the existing mechanism, however
just one more thunk type will need a more sophisticated design.
Current thought is to try and implement the basic design to learn a
bit more about the mechanism as it will hopefully not take too long.
== Progress ==
* Remove exit-on-error flag from CodeGen tests [TCWG-604] [4/10]
- This is a follow-up of TCWG-592: when changing the diag handler,
some of the tests started to fail, so we had to add an exit-on-error
flag to preserve the old behaviour until we can fix the tests.
- Patch fixing the MIR tests (PR27770) - committed upstream
- Submitted a patch fixing one of the AMDGPU tests (PR27761) - in
upstream review
- Submitted a patch fixing the ARM test (PR27765) - in upstream review
* Use git worktree in llvm helper scripts [TCWG-587] [1/10]
- Minor fixes during the review, hopefully we can wrap it up soon
* ARM: Do not test for CPUs, use SubtargetFeatures [TCWG-623] [3/10]
- Investigated uses of isCortexA*, isSwift etc in the ARM backend
- Started extracting subtarget features for the easy ones
* LLVM ARM 3.8.1 [TCWG-642] [1/10]
- Ran the ARM tests for the LLVM 3.8.1 release
* Investigate clang-cmake-thumbv7-a15-full-sh failure [TCWG-635] [1/10]
- Found patch that was causing problems, started discussion about it
on the mailing list
== Plan ==
* Remove exit-on-error flag from CodeGen tests [TCWG-604]
- Address any code review comments
- After committing the 2 remaining patches, we should be able to
remove the flag and wrap this up
* ARM: Do not test for CPUs, use SubtargetFeatures [TCWG-623]
- Extract more subtarget features
* OOO on Monday
== This Week ==
* LTO (6/10)
a) increase_alignment (2/10)
- posted patch upstream to convert it to regular pass
b) TCWG-548 (3/10)
- Lava job #3424 failed with timeout (same as #3370)
- Experimenting with partition sizes with and without the patch for
different benchmarks,
results consistently show a significant difference in last partition size.
- Trying a new approach.
c) TCWG-535 (1/10)
- posted partial patch upstream:
https://gcc.gnu.org/ml/gcc-patches/2016-06/msg00143.html
* TCWG-72 (2/10)
- Further patch iterations
- Approved by Richard
* Misc (2/10)
- Looked at function versioning.
- Wrote patch to address missing diagnostic in C/C++ FE, fails on bootstrap.
- Meetings
== Next Week ==
- TCWG-548: Implement new approach and experiment with it.
- ipa-vrp: Apply Kugan's prototype patch, and test it, sync on early vrp.
- TCWG-72, TCWG-319, TCWG-535, increase_alignment: ping for reviews.
- Travel to Mumbai on Monday for Schengen Visa appointment
== Progress ==
o Upstream GCC (4/10)
- Continuing ARMv8.1 libatomic investigation
(some infra issues now fixed)
o Misc (6/10)
* Various meetings and discussions.
* patch reviews
* Benchmarking notification investigation
* Booked Hotel and flights for tcwg sprint
== Plan ==
o Continue libatomic
o GCC 5.4 branch merge
o Benchmarking notification
== Progress ==
Fixed Bugs and posted patches for review
- PR71281 and PR71408
PR66726 - Convert expr
- Found way to handle this well and posted a patch.
IPA VRP
- Started with a simple implementation for intra-procedural early VRP
by refactoring tree-vrp.
- Still need to handle range dominance
- Ran into a latent issue in tree-vrp. Looking into it.
== Plan ==
- Follow upon remaining upstream patches
- IPA VRP
On 3 June 2016 at 17:10, Rafael Espíndola <rafael.espindola(a)gmail.com> wrote:
> Do keep in mind you are comparing a 11 year old project and a 11 month
> old one. There is a lot more churn on the 11 month old one.
LLD is at least 5 years old. Every time you re-write it doesn't reset history.
> Again, I am truly sorry we were unable to come up with a perfect
> design the first time. For the record, I don't think it is perfect
> yet. There will likely be more big changes to lld. That is the cost of
> trying to build as good a linker as we can.
This is not about what you do. It's about *how* you do it.
We have developers trying to create a linker. They are working on LLD
because Chris wanted a true LLVM linker. But it seems that you want a
project that you can do whatever you want, whenever you want.
This is *NOT* open source. Right now, LLD is *nothing more* than Rui's
and Rafael's pet project. I cannot recommend Linaro to collaborate on
those terms, and I sincerely recommend anyone that is listening to
this thread to not do so either.
> Being open source doesn't mean I get to implement what someone else
> wants. You are more than welcome to send patches, but they have avoid
> harming the rest of the linker. In particular, at this early stage
> they cannot harm its development. Once we have a mature project we can
> actually evaluate tradeoff.
We're clearly not welcome to send patches. We did, and you re-wrote it
and committed without asking the original author.
So, the plan is to wait for you to finish the initial implementation
alone? Again? What do we do in the interim? How many times are we
going to go through this?
I have waited 2 years before LLD was barely useful, then Adhemerval
implemented the AArch64 back-end. Then you destroyed and now we have
waited another year, but we're still unable to collaborate. If
anything, now it's even harder than it was last year.
Why can't we help with the design, too? We know about ARM and AArch64,
that's what we do, and we can provide you with the expertise without
having to go on your own doing everything. That is the whole point of
collaborative development, and it seems that you're missing this
point.
> And just like we did, you are more than welcome to try to write
> something better. Please let us know how it goes.
Is this the position of every LLD developer?
Rui, Nick, Chris?
I'm seriously looking for others to chime in and let me know if that
is the final stance on LLD, so that I can finally write it off and go
work on another linker.
If the official position is that LLD is a project that only Rui and
Rafael can design and implement for another 2~3 years, I *cannot*
recommend Linaro and its members to participate.
cheers,
--renato
== Progress ==
- Holiday Monday/Tuesday
- Finished writing initial support for ARM in lld. Posted upstream as
RFC, no comments so far.
- Implemented, but not tested the static Thumb relocations present in
the arm-linux-gnueabihf-gcc
-- I'd forgotten how much I hated the Thumb 2 instruction encodings.
== Plan ==
- Add tests for Thumb relocations
- Start thinking about how interworking can be implemented in lld
* Monday off [2/10]
# Progress #
* TCWG-518, arm linux range stepping. [4/10]
Finished V2, and send them out for review.
More bugs in existing GDBserver are found, fixed them as well.
8 patches become 12 patches.
* Upgrade linux kernel on chromebook to verify Russell King's ptrace
fix.
http://lists.infradead.org/pipermail/linux-arm-kernel/2016-May/431972.html
[3/10]
This may be the cause of unstable result of GDB floating point tests,
and they are tracked by GNUTOOLS-4858.
4.6.1 is running on chromebook now, but haven't try the patch yet.
* TCWG-547, "align software single step in other targets with arm's
implementation".
Patches are pending for review. Pinged Pedro to give a review.
* Misc, [1/10]
** Commit fix to PR 19998, and review the follow-up patch.
** meeting and training,
# Plan #
* TCWG-518, TCWG-547, TCWG-333
--
Yao
== Progress ==
* Remove exit-on-error flag from CodeGen tests [TCWG-604] [4/10]
- This is a follow-up of TCWG-592: when changing the diag handler,
some of the tests started to fail, so we had to add an exit-on-error
flag to preserve the old behaviour until we can fix the tests.
- Patch fixing the MIR tests (PR27770) - still in upstream review
- Submitted another patch fixing two other BPF tests (PR27768/9) -
committed upstream
- Submitted a patch fixing one of the AMDGPU tests (PR27761) - in
upstream review
- Investigating the ARM test (PR27765)
* Use git worktree in llvm helper scripts [TCWG-587] [4/10]
- In review, hopefully we can wrap it up soon
* Misc [2/10]
- More LLVM backend education (MI level), ARM ARM etc
== Plan ==
* Remove exit-on-error flag from CodeGen tests [TCWG-604]
- Fix the ARM test
* Use git worktree in llvm helper scripts [TCWG-587]
- Fix a regression in the error-handling
- Address review comments
On 2 June 2016 at 23:22, Rafael Espíndola <rafael.espindola(a)gmail.com> wrote:
> Because the patch includes way too much and doesn't explain what it is doing.
So let me get this straight: someone publishes a patch, you don't like
it, you do some private investigations and commit whatever you want
without even notifying the original authors?
I don't know how you work at your company, but this is not how open
source development works.
This is not the first time either that you step over people's toes
with your "design decisions" that you don't share with anyone. Last
year, Adhemerval has worked for three months to get the LLD AArch64
back-end working and out of the blue, no warning, the whole back-end
was yanked.
It doesn't matter if it was the right decision or not in the long
term, we don't just yank things, especially not before some
deliberation on the list. See how long is taking for the new pass
manager to be enabled, or FastIsel or the new Selection, or the new
register allocators, etc.
That's not how open source works and I assumed you knew that.
> That is a general problem with aarch64, the documentation is missing
> and comments have to make due. I had a lot of work to rewrite the
> original aarch64 patches to be in line with the rest of lld and I
> didn't want to have to do the same for tls.
You shouldn't be rewriting *any* patch, but asking the original
authors to do that themselves.
There is a pattern that I'm seeing and that's that *you* refuse or
dismiss more patches than most other people. There are many of your
comments on reviews that are just personal, and then you step over
people's toes and commits yourself.
This does not scale. But more importantly, it puts into doubt the
validity of the tool you're so hardly defending.
You see, 3 years ago, I was asked to choose between MCLinker and LLD.
MCLinker was a linker for all purposes, but Chris Lattner convinced me
that LLD is the LLVM linker, and we should be focusing all efforts
there.
It goes against the commercial interests of Linaro members to choose
such a premature technology, and it did put them back years of
development, because MCLinker was very close to ready, and MediaTek,
despite what people said, was very willing to accept our help.
But in the interest of the community, and the open source nature of my
work, I have decided to pursue LLD and managed to convince Linaro to
put two people working on it. But now, I'm re-evaluating all my
strategy, and sincerely, I do not trust the LLD community anymore.
> The delay was because of the above mentioned issues. I wanted to make
> sure there was a solid foundation.
Some patches are quick to review, others take 6 months. If you work in
open source you have *got* to understand that. If you're not willing
to take that cost, than please, refrain from working open source.
> Sorry, no.
I understand your position, but you have to understand mine. I
therefore call into question your ability to care about such an
important project of the LLVM community.
I sincerely believe that your actions are harming the project, and the
people trying to help. I appreciate the value of your contribution, I
really do, but if you don't change your way to handle open source
contributions, LLD will, whether you like it or not, become irrelevant
and be replaced.
Such is the nature of open source.
cheers,
--renato
On 2 June 2016 at 20:49, Rafael Espindola via llvm-commits
<llvm-commits(a)lists.llvm.org> wrote:
> Author: rafael
> Date: Thu Jun 2 14:49:53 2016
> New Revision: 271569
>
> URL: http://llvm.org/viewvc/llvm-project?rev=271569&view=rev
> Log:
> Start adding tlsdesc support for aarch64.
>
> This is mostly extracted from http://reviews.llvm.org/D18960.
Rafael,
Why commit part of Adhemerval's patch without reviewing his request?
This is a really serious breach of community trust.
Not only we're waiting for reviews on the TLS set of patches and
having to rebase every two weeks, but now you implemented in a way
that wasn't discussed on the review, didn't mention authorship, nor
asked Adhemerval for any input.
If you had technical input on his patch, you should have done on the
review. If you wanted him to split in smaller patches, you should have
asked on the review and let *him* do it.
Even if you were the code owner (which you're not), it would still be
a *serious* breach of trust and respect.
I hereby respectfully request that you revert your patch and let
Adhemerval finish the work that he started in the way that we normally
do in the LLVM community.
regards,
--renato
* Off on Friday [2/10]
# Progress #
* TCWG-518, V1 got reviewed, and working on V2. Two existing bugs in
GDBserver are found, and fixed. Testing them... [4/10]
* Upstream patches review, all of them are about GDB python. [2/10]
* Respond to Jim Wilson's question on AIX GDB build failure caused by
his binutils patch for AArch64. Confirm that GDB build fail after
his patch. [1/10]
* Misc, [1/10]
# Plan #
* Bank holiday on Monday,
* TCWG-518, get V2 ready for review,
* Ping TCWG-561 and TCWG-547,
--
Yao
=== This Week ===
Resolved TCWG-231 (LLDB bring up and bug fixing on HiKey 96Board)
[TCWG-231] [1/10]
-- Ran tests on AArch64 LLDB tests on HiKey and compared with Nexus 9
test results.
-- Less than 1% difference in test results and good pass rate found.
LLDB ARM: Bug fixes, integration and testing on various ARM platforms
[TCWG-228] [2/10]
-- Progressed towards resolution.
-- Prepared close out setting up RaspberryPi2, RaspberryPi3, Hikey and
Chromebook as testers.
-- Compiled armhf test results.
LLDB Chromebook Test Stability [TCWG-563] [2/10]
-- Some further investigation on llvm-chrome-06 test failures.
-- Marked and committed some xfails and reported relevant bugs if not
already logged.
Support for watchpoint un-alligned watchpoint addresses on LLDB
AArch64 [TCWG-367] [1/10]
-- Debugging of watchpoint handling code and tried out instruction decding.
LLDB buildbot updates and maintenance [TCWG-241] [2/10]
-- Improved tester script to initiate lldb-server inside a chroot.
-- Monitored buildslave stability and
Miscellaneous [2/10]
-- Meetings, emails, discussions etc.
-- Migrated laptop to Ubuntu 16.04
=== Next Week ===
LLDB Chromebook Test Stability [TCWG-563]
-- Final words on watchpoint issue on llvm-chrome-06
-- Submit updated makefile.rulez for LLDB tests.
-- Report remaining bugs and commit xfails upstream.
Support for watchpoint un-alligned watchpoint addresses on LLDB
AArch64 [TCWG-367]
-- Implement instruction decoding for watchpoint hit detection.
A look into kernel code used by Nexus android devices failing
watchpoint support [TCWG-622]
Miscellaneous
-- Out of office on Tuesday 31st 2016 for visa documents preparation.
* ! day off (2/10)
== Progress ==
o Extended validation (2/10)
- Benchmarking comparison script on-going
- Reproduced armhf schroot slowness on AArch64 Debian Jessie
No issues when using Ubuntu (Trusty and Xenial).
o Upstream GCC (4/10)
- Started ARMv8.1 libatomic support
(environment setup, code understanding, ifunc support analysis)
o Misc (2/10)
* Various meetings and discussions.
== Plan ==
o Continue libatomic work
== This Week ==
* TCWG-72 (6/10)
- Patch iterations based on Richard's suggestions
- Reworked most of convert_to_divmod()
- Fixing regressions with the patch and added test-cases.
- ICE with -m32 on x86_64 for DImode division/mod:
https://gcc.gnu.org/ml/gcc-patches/2016-05/msg02302.html
* LTO (2/10)
a) TCWG-548 (1/10)
- Benchmarking jobs submitted twice and failed.
b) TCWG-535 (1/10)
- Figured out why ICE happens with my patch.
* TCWG-319 (1/10)
- Validated patch and posted upstream.
* Misc (1/10)
- Meetings
== Next Week ==
- TCWG-72: Try to workaround issue with -m32
- TCWG-548: start relooking at section anchors.
- TCWG-535: Post patch upstream.
== Progress ==
PR71252 - ICE in rewrite_expr_tree
- Tried various options to fix this and settled on an implementation
- Patches sent for upstream review
- tested with cpu2006 too
- One patch approved
PR66726 - Convert expr
- Newlib test case is failing due to mi compiled lib
- Trying to reduce test case
== Plan ==
Follow upon remaining upstream patches
IPA VRP
== Progress ==
* LLD Port:
- Got hello world running.
-- Needed a horrible hack to make lld output PLT and GOT entries for
unresolved weak references with default visibility.
- Wrote up in Jira the major areas of work that would be needed for a
useful port.
- Started putting in changes cleanly and writing tests for them.
- Currently hitting a few problems with llvm-mc. I can't generate the
relocations I need to test the linker. The hello world test case used
mainly GCC library objects.
-- Most serious is not emitting R_ARM_BASE_PREL for .word
_GLOBAL_OFFSET_TABLE - (label+8)
== Plan ==
* On holiday Monday and Tuesday
* LLVM MC
See how easy it would be to add missing features to llvm-mc as it
would allow me to write more tests.
* LLD
Complete the test cases for the code I've added.
Take stock of where the lld port is and decide where to go from there.
Options are:
- Send an RFC upstream with what I have. It is not sufficient to run
hello world but should be relatively uncontroversial.
- Cleanly implement the emit the unresolved weak references in the PLT
and GOT so hello world will work out of the box on ARM.
- Keep going until I've got Thumb2 support so I don't have to use ARM
only static libraries to make hello world working.
There is obviously a trade off between having a useful linker and the
patch size getting out of hand.
== Progress==
* Remove exit-on-error flag from CodeGen tests [TCWG-604] [5/10]
- This is a follow-up of TCWG-592: when changing the diag handler,
some of the tests started to fail, so we had to add an exit-on-error
flag to preserve the old behaviour until we can fix the tests.
- Last week's patch fixing the MIR tests (PR27770) - still in upstream review
- Last week's patch fixing an AMDGPU test (PR27762) - committed upstream
- Last week's patch fixing a BPF test (PR27766) - committed upstream
- Submitted another patch fixing a BPF test (PR27767) - committed upstream
- Submitted another patch fixing two other BPF tests (PR27768/9) -
in upstream review
- Investigating one of the AMDGPU tests (PR27761)
* Use git worktree in llvm helper scripts [TCWG-587] [4/10]
- Started a RFC and a wiki page about the new workflow [1]
- People seem to be in favour of it, but there are still some TODOs
left before we can merge
* Misc [1/10]
- Meetings, buildbots
== Plan ==
* Remove exit-on-error flag from CodeGen tests [TCWG-604]
- Submit a patch for the AMDGPU test (PR27761)
- More investigations on the ARM test (PR27765)
* Use git worktree in llvm helper scripts [TCWG-587]
- Finish the final touches and have a proper review
[1] https://collaborate.linaro.org/display/LLVM/Git+Worktree+Proposal
== Progress ==
* Validation
- cleanup
- Fixed regressions in abe (gcc_update, make install, gdb timestamps)
- updated abe stable branch (now matches master)
- various Jenkins jobs updates, prepared support for gcc-6 based toolchains
- compared results of armv8l vs arm toolchains: few, expected
differences due to different default tuning
* GCC
- regressions reports on trunk
* Misc (conf-calls, meetings, emails, ....)
== Next ==
* Validation
- actually update the Backport job
- prepare switch to docker for buildfarm job
- cleanup
* Backports
* GCC
- trunk monitoring
- more on AdvSIMD intrinsics
Sorry for hitting the wrong mailing list. OK I will check with HTTP instead of HTTPS. Thanks for your time & help.
On May 25, 2016 11:02 PM, Jim Wilson <jim.wilson(a)linaro.org> wrote:
On Wed, May 25, 2016 at 8:09 AM, Gujulan Elango, Hari Prasath (H.)
<hgujulan(a)visteon.com> wrote:
> I enabled the -v option of wget and I am able to see the download starts and
> fails randomly after progressing to some extent i.e. 10% or 27%. The
> connection is reset by peer and wget exits. I tried increasing the timeout
> option of wget as well.
This is some kind of networking or web server problem. We only know
how to fix compiler problems here on the linaro-toolchain list. I did
confirm that I can download the file OK, both via wget and via
chrome.. I noticed that the https support on releases.linaro.org is
not working, and I had to use http instead, but it isn't clear if that
is related to your problem.
Jim
Hello,
We have cloned the meta-linaro layer and when we build,we are facing some issues when the do_fetch() task is executing for the gcc-source-linaro-5.1 package.
I enabled the -v option of wget and I am able to see the download starts and fails randomly after progressing to some extent i.e. 10% or 27%. The connection is reset by peer and wget exits. I tried increasing the timeout option of wget as well.
Any idea what's wrong. Find attached the log of the error.
Thanks & Regards,
Hari Prasath
Cisco is trying to use clang/lto on big-endian arm, which apparently
requires gold, and gold does not support the --be8 option which is
required for ARMv7 big-endian support. Does anyone here care about
this?
Umesh Kalappa asked about this on the binutils mailing list
https://sourceware.org/ml/binutils/2016-05/msg00209.html
and discovered that it is a known bug reported 5 years ago
https://sourceware.org/bugzilla/show_bug.cgi?id=13213
Jim
== Progress ==
o Extended validation (7/10)
* Investigate GDB instabilities:
- branch tracing issue are due to builder feature support
- Our 2 old builders, which don't support it, removed from x86
validation pool
* Benchmarking:
- Looked at Lava instance API and lava-tool usage and prerequisite
- Implementing comparison script
o Misc (3/10)
* Various meetings and discussions.
== Plan ==
o Continue on validation/benchmarking
o Catch up with upstream work.
=== This Week ===
Support for watchpoint un-alligned watchpoint addresses on LLDB
AArch64 [TCWG-367] [3/10]
-- Made changes to NativeRegisterContext_arm64 to support multiple
watchpoint slot for a single watch address.
-- Enabled unaligned watchpoints and experimented with resulting false
positives.
LLDB Chromebook Test Stability [TCWG-563] [3/10]
-- Migrated local builder to Ubuntu 16.04 xenial
-- Ran LLDB testsuite with GCC 5.x.x on chromebook, raspberryPI2
-- Updated LLDB testsuite makefile.rulez to use correct cross AR and OBJCOPY
LLDB buildbot updates and maintenance [TCWG-241] [2/10]
-- Investigation of LLDB buildbot slave failure
-- Implemented stale log deletion mechanism by making sure we keep
only 10 most recent logs.
LLDB upstream collaboration and Arm/AArch64 Linux port maintenance [1/10]
-- Verify patches under review
-- Analyzed TestTopLevelExprs on LLDB arm failure and committed xfail.
Miscellaneous [1/10]
-- Meetings, emails, discussions etc.
-- Travel bookings for connect and TCWG sprint.
=== Next Week ===
Close out TCWG-231 (LLDB bring up and bug fixing on HiKey 96Board)
-- Run and comparison of AArch64 LLDB test results vs hikey showing
less than 5% difference.
Close out LLDB Chromebook Test Stability [TCWG-563]
-- Make sure there are no failures for which we dont know the underlying reason.
-- Report remaining bugs and commit xfails upstream.
Support for watchpoint un-alligned watchpoint addresses on LLDB
AArch64 [TCWG-367]
-- Further testing of false positive results due to allowing
un-alligned watch-points.
LLDB buildbot updates and maintenance [TCWG-241]
-- Figure out difference of test results between local and remote chromebooks.
-- Figure out a way to hide unused test slots by buildbot factory.
Miscellaneous
-- Migrate laptop to ubuntu 16.04 in hope of better driver support.
-- Portugal visa and travel booking
== Progress ==
* Validation
- cleanup
- reviews
- asserting ABE master vs stable results
- stopped investigation on a huge number of unexpected
regressions, maybe caused by builders crashes
- created a Jenkins job able to detect the base GCC
branch, in order to select the right libc/binutils version
- found why ABE master showed regressions with the
_Pragma3 GCC test. Fix under review.
- investigating recent, numerous build failures
* Backports
- updated backport to fix bug #2185 after Kugan analysis
- drafted a script to parse the spreadsheet and generate
the backflip commands as appropriate
* GCC
- reported a couple of regressions on trunk
- Neon intrinsics tests update: committed.
We are now ready to remove neon-testgen.ml
== Next ==
* Validation
- cleanup
- armv8l vs arm
- ABE master vs stable
* GCC
- trunk monitoring
- more on AdvSIMD intrinsics
== Progress ==
PR40921 -missed optimization: x + (-y * z * z) => x - y * z * z
- Patch committed
PR63586 - x+x+x+x -> 4*x in gimple
- Patch committed
- There were couple of fallouts
PR71179 - ICE fold_convert_loc, at fold-const.c:2360
- Patch committed
PR71170 - ICE in rewrite_expr_tree, at tree-ssa-reassoc.c:3898
- Tried various options to fix this and settled on an implementation
- Patch sent for upstream review
== Plan ==
Follow upon remaining upstream patches
IPA VRP
== This Week ==
* TCWG-528 (2/10)
- Addressed comments from Richard and committed upstream (r236502, r236503)
* TCWG-72 (5/10)
- Updated patch and fixed regressions caused due to patch.
* TCWG-319 (1/10)
- Found why big endian vectorizer was not vectorizing the test-case with -O2.
* Holiday (2/10)
== Next Week ==
- TCWG-319: Post patch upstream and get it committed.
- TCWG-72: Post patch upstream and hopefully get it committed this week.
- TCWG-548: Start re-looking at section anchors.
=== Progress ===
TCWG-591 MOVW incorrectly allowed on ARM v5 committed upstream
TCWG-595 LLD port to ARM architecture
I am getting close to being able to run hello world built with lld.
I'm converging 1 bug at a time.
- The PLT handling code is working and the loader can execute the
image and starts the .init function.
- Currently failing in the weak call to __gmon_start__. At present lld
is removing undefined weak references from executables instead of
passing them on for the dynamic loader to resolve. This may not be
necessary on x86 but it is necessary on ARM.
-- Just finished a hack that should make this work, although it will
need some tidying up.
=== Plan ===
Get hello world working and then take stock of what I've learned and
come up with a plan in Jira for what needs to be done.
== Progress ==
* Add a diag handler for llc so it doesn't exit on the first error it
finds [TCWG-592] [1/10]
- Fixed and rebased the patch, it has been committed upstream
* Inline assembly constraints support for ARM [TCWG-560] [1/10]
- Rebased the patch, it has been committed upstream
* Remove exit-on-error flag from CodeGen tests [TCWG-604] [4/10]
- This is a follow-up of TCWG-592: when changing the diag handler,
some of the tests started to fail, so we had to add an exit-on-error
flag to preserve the old behaviour until we can fix the tests.
- Submitted a patch fixing the MIR tests (PR27770) - in upstream review
- Submitted a patch fixing an AMDGPU test (PR27762) - in upstream review
- Submitted a patch fixing a BPF test (PR27766) - in upstream review
- Investigated the ARM test (PR27765)
* Use git worktree in llvm helper scripts [TCWG-587] [3/10]
- Working on a prototype
* Misc [1/10]
- Meetings, buildbots, IRC issues
- Got LLVM commit access, yay!
== Plan ==
* Remove exit-on-error flag from CodeGen tests [TCWG-604]
- Fix the remaining ARM, BPF and AMDGPU tests (unfortunately the ARM
test seems a bit more involved, so I might pick out the others first
just to get them out of the way)
* Use git worktree in llvm helper scripts [TCWG-587]
- Continue prototyping, start a RFC on it next week
# Progress #
* TCWG-518, [6/10]
fix all bugs, and post them upstreams for review!
* PR 19998, write a patch to fix it. [2/10]
* Some discussions on unstable GDB test results in validation tests.
[1/10]
* Meetings [1/10]
# Plan #
* Respond comments to my patches,
* TCWG-333, think about the right fix.
--
Yao
This may be a better question for the linaro tools group. +cc their list
for the general question of conventions surrounding how shared library
objects identify and access thread-local storage that they need as part of
calling threads.
On Tue, May 17, 2016 at 11:06 AM, Nikhil Agarwal <nikhil.agarwal(a)linaro.org>
wrote:
> Hi All,
>
> I am trying to write a shared library object over ODP. Our ODP library has
> some per thread variables. When my application invokes an API of shared
> object which accesses per thread variable it gives segmentation fault.
>
> My concern is that when a shared object is loaded dynamically, how memory
> is assigned to thread specific variables defined inside shared objects.
> AFAIK we need to compile it with -ftls-model=global-dynamic, which is
> enabled by default when compiled with -fPIC flag, and library loader
> takes care for these issues.
>
> I am not an expert in this area, please help me in getting to some
> suitable reference pointers or some steps I might have missed.
>
> Thanks in advance
>
> Nikhil
>
=== This Week ===
Enable LLDB testsuite to show zero failures on Hikey 96 Board (AArch64
Linux) [TCWG-231] [4/10]
-- Ran multiple builds and testsuite runs to figure out latency issues.
-- Investigated remaining failures and submitted appropriate bugzilla bugs.
-- Committed xfails upstream.
Support for watchpoint un-alligned watchpoint addresses on LLDB
AArch64 [TCWG-367] [1/10]
-- Some investigation on possible solutions and frequently encountered
scenarios.
LLDB Chromebook Test Stability [TCWG-563] [3/10]
-- Investigation of noreturn unwinding test failure
-- Investigation of step over load library call failure
-- Investigation of other failures and commit xfails for reported issues.
Miscellaneous [2/10]
-- Meetings, emails, discussions etc.
-- Portugal visa information gathering
=== Next Week ===
Support for watchpoint un-alligned watchpoint addresses on LLDB
AArch64 [TCWG-367]
-- Add code changes required to manage a watchpoint with multiple
hardware watchpoint resources.
LLDB Chromebook Test Stability [TCWG-563]
-- Fix noreturn unwinding test failure and report relevent bug.
-- Fix step over load library call failure or report relevent bug.
Miscellaneous
-- Portugal visa application documents preparation.
== Progress ==
* Validation
- cleanup
- reviews
- looked a bit a using docker from Jenkins
- investigating how to select toolchain components versions
depending on the gcc version
* GCC
- Sent Neon intrinsics tests patches.
- trunk timeouts: caused by the libcilkrts merge, which has a bug on
arm. Disabled cilkplus to avoid too much noise in the results.
- reported a couple of regressions/bisects
* Misc (conf-calls, meetings, emails, ....)
- support for M-profile related queries ( multilib etc...)
== Next ==
* Validation
- cleanup
- reviews
- armv8l vs arm
- multiple gcc branches vs other components versions handling
* GCC
- trunk monitoring
- some dev if time permits
== Progress ==
o Linaro GCC (5/10)
* Linaro GCC 5.3 2016.05 snapshot
- FSF branch merge + release
* Linaro GCC 6.1 2016.05 snapshot
- Create new branch + release
o Extended validation (3/10)
* Fixed validation issues when binary tarballs are created.
o Misc (2/10)
* Various meetings and discussions.
== Plan ==
o Continue on validation/benchmarking
o Catch up with upstream work.
== Progress ==
* Add a diag handler for llc so it doesn't exit on the first error it
finds [TCWG-592] [5/10]
- Started a discussion about a new diagnostic handler for llc
- Patch accepted upstream, but broke a few things (Renato has
investigated/fixed some of them - thanks)
* Inline assembly constraints support for ARM [TCWG-560] [5/10]
- Patch in upstream review, but should be committed after the new
llc diagnostic is in place (otherwise it's difficult to test it
meaningfully)
== Plan ==
* Add a diag handler for llc so it doesn't exit on the first error it
finds [TCWG-592]
- Fix the remaining issues and get the patch committed again
* Inline assembly constraints support for ARM [TCWG-560]
- Rebase patch and try to get it reviewed
* Investigate exit-on-error on LLC [TCWG-594]
- Track the tests that need the exit-on-error flag with the new
diagnostic handler
== Progress ==
- ldr rt,= implementation transform to MOV committed upstream
[TCWG-468] [PR25722]]
-- Thanks to Renato for committing.
- Started looking at what would be needed to port lld to ARM
-- The ELF lld port looks to have a fairly small amount of
architecture specific hooks. Decided that I would learn fastest by
just trying to do an ARM only prototype port to see if I could get
hello world on linux working.
-- spent too much time trying to think about how to best implement the
group relocations for the PLT sequences then remembered that for a
quick prototype I could use larger sequences that didn't need the
relocations.
== Plan ==
- Continue working on an ARM LLD port. Will hopefully have a good idea
of what the scope of work needed is next week.
The Linaro Toolchain Working Group (TCWG) is pleased to announce the
2016.05 snapshot of both Linaro GCC 5 and Linaro GCC 6 source
packages.
Linaro GCC 6 monthly snapshot[1] is based on FSF GCC 6.1+svn236106 and
includes performance improvements and bug fixes backported from
mainline GCC. This snapshot contents will be part of the 2016.08
stable[2] quarterly release.
This snapshot tarball is available on:
http://snapshots.linaro.org/components/toolchain/gcc-linaro/6.1-2016.05/
Interesting changes in this GCC source package snapshot include:
* Updates to GCC 6.1+svn236106
Linaro GCC 5 monthly snapshot[1] is based on FSF GCC 5.3+svn236108 and
includes performance improvements and bug fixes backported from
mainline GCC. This snapshot contents will be part of the 2016.08
maintenance release.
This snapshot tarball is available on:
http://snapshots.linaro.org/components/toolchain/gcc-linaro/5.3-2016.05/
Interesting changes in this GCC source package snapshot include:
* Updates to GCC 5.3+svn236108
* Backport of [Bugfix] [AArch32] PR target/70711 Fix big-endian ARMv8.1-A builds
* Backport of [Bugfix] [AArch64] PR target/70044 -flto turns on
-fomit-frame-pointer
* Backport of [AArch32] Reduce size of arm1020e automaton
* Backport of [AArch64] Fix SIMD predicate
* Backport of [AArch64] Fix thinko in handling of
-momit-leaf-frame-pointer option
* Backport of [Testsuite] [AArch32] Tests for arm_restrict_it patterns
in thumb2.md
* Backport of [Testsuite] gcc-dg: handle all return values when
shouldfail is set
Subscribe to the important Linaro mailing lists and join our IRC
channels to stay on top of Linaro development.
** Linaro Toolchain Development "mailing list":
http://lists.linaro.org/mailman/listinfo/linaro-toolchain
** Linaro Toolchain IRC channel on irc.freenode.net at @#linaro-tcwg@
* Bug reports should be filed in bugzilla against GCC product:
http://bugs.linaro.org/enter_bug.cgi?product=GCC
* Interested in commercial support? inquire at "Linaro support":
mailto:support@linaro.org
[1]. Source package snapshots are defined when the compiler is only
put through unit-testing and full validation is not performed.
[2]. Stable source package releases are defined as releases where the
full Linaro Toolchain validation plan is executed.
== Progress ==
* 3 days off (Mon/Thu/Fri) [6/10]
* Inline assembly constraints support for ARM [TCWG-560] [3/10]
- More investigations for PR24071; found the cause of the bug,
working on a fix.
* Rework LLVM helper scripts [TCWG-571] [1/10]
- Addressed code review comments.
- The interface changes to llvm-projs and llvm-sync are now committed.
== Plan ==
* Inline assembly constraints support for ARM [TCWG-560]
- Come up with a fix for PR24071
* Rework LLVM helper scripts [TCWG-571]
- Investigate git worktree and how it could be factored into our
scripts (llvm-projs, llvm-build)
o 2 days off (4/10)
== Progress ==
o Extended validation (4/10)
* Change extended native job to use multiple scm
* Investigate validation issues when binary tarballs are created
o Linaro GCC (1/10)
* Finalized and submitted new Linaro development branch script.
o Misc (1/10)
* Various meetings and discussions.
== Plan ==
o Create Linaro GCC 6 branches
o Continue on validation and upstream work.
* 2 days off (Thu/Fri)
== Progress ==
* Validation
- restarted validations for pending backports, after the various
branches updates
- started looking at armv8l vs arm results differences
* GCC
- checked trunk regression reports
- updated AArch32 Neon intrinsics tests. Patch series almost ready
for submission
* Misc (conf-calls, meetings, emails, ....)
== Next ==
* Validation
- cleanup
- reviews
- armv8l vs arm
* GCC
- trunk monitoring: check why builds were killed after timeout
- more intrinsics tests
== This Week ==
* LTO (7/10)
a) TCWG-548 (2/10)
- Fixed a minor bug in the patch
- Results of variable partitions with chromium: http://pastebin.com/fLD2JzgP
- Significant difference in size of last partition could probably
indicate sth wrong with
patch (all unpartitioned variables go to last partition).
b) TCWG-528 (3/10)
- Posted upstream after bootstrap+test passed on ppc64le-linux-gnu
- Addressed Richard's comments.
c) TCWG-299 (2/10)
- Firefox built on aarch64 natively (r1-a12) non LTO with gcc-5 branch
- Fails to build with trunk due to issues in firefox codebase (PR70722)
- Fails to build on armhf with following error: http://pastebin.com/9xydVtjj
* TCWG-72 (2/10)
- Rebased patch
- Addressed Ramana's comments
* Misc (1/10)
- Meetings
== This Week ==
- LTO: benchmark section anchors patch, submit patch for
increase_alignment upstream, firefox
- TCWG-72: Test and submit upstream