Activity:
[TCWG-1384] Add support for missing TLS local exec relocations tl LLD
Have an implementation ready to go upstream next week. In process
found that Gold and BFD disagreed on test output. Turns out that there
was a bug in BFD, reviewed Renlin Li's patch for it. Took rather more
of my time than I expected.
[TCWG-1375] Set 4 patches upstream to complete the removal of the
global subtarget
No response as yet.
Raised https://bugs.llvm.org/show_bug.cgi?id=37212 clang and gcc are
producing technically illegal ELF for debug information (references to
local symbols defined in comdat groups), both gold and bfd have
special case code to handle this case, lld does not. Leads to loss of
debug illusion for templated and inlined C++ functions.
Other
- Some research into how spec files and multilib works in gcc to see
how it could fit into clang's driver model.
- Joined the ELF ABI google group to fulfil a promise I'd made at Euro
LLVM to comment on a thread about debug information in comdat groups.
Holiday on Tuesday
Plans:
- Ping reviews.
- Push fix for TCWG-1384 upstream alongside some refactoring patches.
- Add some more tests to LLD to close some holes in the code-coverage
statistics.
- Continue looking at laundry list of small LLD changes.
- Get back to building Android.
=== Work done during this GCC week ===
* stack-protector failure on GCC ARM: need feedback from community
+ prevent CSE of stack protector's guard first by adding some extra
UNSPEC then instead by making all memory accesses involved volatile
+ write 2 monstro regex (251 & 377 characters respectively) to catch the
bug on ARM, Thumb-2 and Thumb-1
+ testing and will submit for review later today once I have all test
results
+ discuss raising a CVE
* Misc:
+ Arm meetings
+ Meeting with ST to discuss how to implement something akin to multilib
+ spec files for LLVM
+ Linary syncs
+ review of "Implement getConstraintRegister for ARM and AArch64" patch
by Mikhail Maltsev
=== Plan for weeks up to 25 ===
* Paternity leave
* Get stack-protector failure fix committed
* DSGHACK-25 (Support arithmetic on FileCheck regex variable): finish patch
* Start looking into LLVM SPEC optimizations Linaro tickets
Progress:
* VIRT-65 [QEMU upstream maintainership]
+ 2.12 release kicked out the door; hopefully I can do a bit more
actual development work for a bit now...
+ investigating problems with execute-in-place-from-MMIO-device
functionality : the test case (for a Xilinx board model) crashes
reliably for me. I cooked up an RFC patch and sent it, but it
includes one weird hack and I'm not sure if it's the right approach...
+ we got a Coverity Scan run through after a couple of months of not
having one, and a pile of issues have accumulated. Waded through some
of them and flagged them up with the patch submitters who added the
code that introduced them.
Notes:
* QEMU will have not one but two interns working on Cortex-M0
and micro:bit support (one from Google Summer of Code and
one from Outreachy) !
* QEMU turns 15 years old this year. To celebrate we plan to
make the next release be 3.0 (and perhaps to have birthday
cake at KVM Forum?)
thanks
-- PMM
* GCC Benchmarking
- Tried Jenkins jobs for trunk benchmarking and posted a patch to
fix -std=legacy needed for gfortran
- Going over the job definitions to add support for SPEC2017
* LLVM
- Looking at spec2006 difference compared to gcc in astar due to
speculative devirtualization not happening
- Going over the background material in Honza's blog and LLVM presentations
[QEMU Upstream]
Fix for softfloat scalbn, broken during the 2.12 reorg.
Code review for Alex's tcg/tests patchset.
Produced a script describing how to build cross-compilers.
[VIRT-198 # QEMU: SVE Emulation Support ]
Fix an tcg generic vector assert hitting SVE w/ VQ=3.
Rebase and post cleanup patch for TCGv_ptr operations.
Finished round 2 of SVE cleanup and fixes. RISU now once
again passes for VQ in [1-4] (which is the limitation of
the FoundationModel against which we are generating trace files).
I'll note that a lulesh binary that I generated for HKG18
does not work on the branch, but does under FoundationModel.
Therefore there must be remaining emulation errors.
However, it's a really complicated binary that is non-debuggable.
Adding printfs interferes with vectorization and gdb does not
yet let us print all of the relevant registers.
My thoughts from here go toward running the gcc testsuite,
and seeing what can be uncovered by those smaller examples.
r~
Progress:
Monday Tuesday at Euro LLVM, trip report at
https://collaborate.linaro.org/display/CR/20180416+EuroLLVM+2018
Found an example that shows that both gold and ld attempt to fix up
illegal "by strict interpretation of ELF" local debug references to
discarded local symbols from rejected comdat groups.
[TCWG-1375] LLVM should do relaxation per function.
- Worked out what instruction bundling is (From NaCl) and how it
relates to MCFragments.
- Posted revised patch upstream to handle relaxation and fixups, now
diagnoses attempt to change MCSubtargetInfo mid bundle.
- I have a finished a large series of patches to pass the
MCSubtargetInfo through to all the places it needs to be including
writeNops. Will post upstream review next week.
Next week:
- Post revised patches to TCWG-1375 and ping reviews.
- Work through a laundry list of small things to do in LLD.
- Get back to trying to link Android AOSP with LLD.
=== Work done during this GCC week ===
* TCWG-1379 (stack-protector failure on GCC ARM): need feedback from
community
+ reproduce on trunk and find out why it happens on ARM and not AArch64
or x86
+ find potential issue for all targets as well, though less likely
+ find discrepencies between code and documentation and wondered if code
is not overly zealous in some case
* 2 days doing Arm handover & meetings
=== Plan for next week (week 12) ===
* Progress on stack-protector failure
* Support arithmetic on FileCheck regex variable: finish patch
Progress:
* VIRT-65 [QEMU upstream maintainership]
+ sent another patch related to linux-user signal frames (a wrinkle
I had thought had no effect with SVE disabled turns out to be
relevant in the no-SVE case too)
+ testing and applying patches for 2.12 rc4
+ code review:
- latest spin of the SMMUv3 emulation patches
- some last-minute fixes to our softfloat refactoring
- memory barrier handling in the 32-bit arm TCG backend was broken
+ tracked down a zephyr test failure on QEMU as the same bug in
the Zephyr timer device driver as the one I reported 6 months ago...
+ sent a patch fixing linux-user emulation of getdents syscall for
64-bit guest on 32-bit host
+ sent a patchset that removes the long-standing "only 4 serial ports"
limit in QEMU (various Arm boards really have 5 or 6)
+ some patches fixing errors in arm boards that don't properly
register all their RAM regions for migration
thanks
-- PMM
[VIRT-198 # QEMU: SVE Emulation Support ]
Cleaning up patches and fixing RISU failures.
[UPSTREAM]
Review of the tb_lock patch set.
Finish review of the v2 TranslateOps patch set.
Pushed a couple of softfloat fixes and an icount fix for 2.12.
r~
Note1: working for Linaro every other week
=== Issues ===
* IT issues made me loose 1 day of work
=== Work done during this LLVM+GCC week ===
* LLVM PR34170 (crashes with inline asm with double output operand in GPR):
internal review
+ improved patch to also support case with several output operands
-> had to choose to relax test a bit to not put expectation on
register allocator
* Support arithmetic on FileCheck regex variables: in progress
+ an attempt to be able to express that 2 registers are related by some
arithmetic expression (eg. vmov dY, rX, rX+1), seems doable
Upstream work on Arm GCC side:
cmse_nonsecure_caller return wrong answer: backported to GCC 7
* __builtin_arm_set_fpscr crashes with literal values input: committed to
trunk, backport oked
+ do more testing and prepare backport to GCC 6 & 7
* PR85344 (GCC fails constraint check on valid code): in progress
+ 2 prototype patches done but inconclusive result
+ pondering what should be the expect behaviour
+ investigating the extent of the problem -> both immediate and register
constraints can be surprising
=== Plan for next week (week 12) ===
* Investigate stack-protector failure with Linaro GCC 7 toolchains
* DSGHACK-25 (Support arithmetic on FileCheck regex variable): finish patch
=== Planned leave ===
* 28th April -> 29th May Sabbatical (Trip to France, then China, then
France again)
Progress:
* VIRT-65 [QEMU upstream maintainership]
+ sent patch fixing problem where some aarch64 binaries would segfault
under linux-user (changes for SVE accidentally caused them to get
a too-small signal frame)
+ wrote an RFC kernel patch which sanitizes the ESR value reported to
userspace for faults on kernel addresses, rather than dropping it
entirely
+ wrote a patch to fix a reported QEMU compile failure for Arm
guests on MIPS hosts
+ code review:
- various bug fixes for 2.12
- another round of the patchset to implement the PMU properly
- DS1338 RTC device emulation overhaul patches
- QEMU side of changes to allow more than 123 CPUs with KVM
(mostly involving allowing split GIC redistributor regions)
- linux-user FDPIC ABI support
Hopefully next week I'll be able to get back to non-release
related work...
thanks
-- PMM
* Short week: off Mon/Tue/Wed
== Progress ==
* GCC
- FDPIC
- binutils: patch series approved, waiting for clarification on target name
- GCC: cleaning patch series, fixing lto problems
* GCC upstream validation:
* Infrastructure:
- Linux kernel + lava failing: still failing, it seems the fix
hasn't been merged yet
- TCWG-1335: GCC validation results now sent to gcc-testresults
- looked at some random problems (?) in our GCC validation
* misc (conf-calls, meetings, emails, ....)
== Next ==
* FDPIC:
- Handle feedback on binutils and QEMU patches
- GCC continue cleanup
* GCC upstream validation
Hi Team,
Could you please let me know which version of toolchain released from Linaro starts to support LTO? Thanks
David
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[TCWG-1375] Make sure MCSubtargetInfo is passed through to
ARMAsmBackend functions
Spent most of the week working on this and follow up patches. Have
submitted a patch for the most important functions. Nearly have one
ready for the correct Nop encoding, this is more complicated as Nops
can be used as padding.
[Plans]
In office Monday Tuesday only.
Progress [TCWG-1375]
Planned Absences:
- At ACCU conference Wednesday - Friday [Holiday]
- At Euro LLVM following Monday Tuesday
[VIRT-198 # QEMU: SVE Emulation Support ]
Cleaning up patches and fixing RISU failures.
Most of these have thankfully been errors in
last week's first pass reordering of the
sve_access_check. Typically wrt when we find
the address of a register vs the location of
the check vs assert_fp_access_checked.
[Upstream]
Examined a bug affecting aa64 guest on ppc64 host,
but only when using gcc 4.8.5 and not gcc 7.2.
Fixed; in the end a minor typo on the code,
but highly annoying to track down.
r~
o 1 day off
== Progress ==
o LLVM
* Buildbots babysitting:
- Investigate LNT failure due to virtualenv and pip versions (Now fixed).
* Working on LLVM benchmarking job
o Misc
* Various meetings and discussions.
Progress: (short week, 2 days)
* VIRT-65 [QEMU upstream maintainership]
+ email/code review/etc catchup following holiday
+ the usual run of admin work for the release process for rc2
+ investigated a problem where in 'icount' mode we weren't
firing timer interrupts in a timely manner; with assistance
from Paolo, tracked down the cause and sent a patch
(https://bugs.launchpad.net/qemu/+bug/1754038)
+ investigated a problem with v7M emulation reported by the LITE team;
this turned out to be a combination of a known limitation combined
with a badly worded warning message; sent QEMU patch which rewords
the message so it's clearer that it's telling you that you're running
into the limitation.
+ tracked down why aarch64 guest binaries run in icount mode on
a 32-bit host misbehave; I have a working but slightly ugly patch
which I'll send out next week unless somebody has a neater approach
thanks
-- PMM
Note1: working for Linaro every other week
Note2: had some important work to do on GCC this week so I'll do some LLVM
work next week as well to catch up
=== Work done during this LLVM+GCC week ===
* LLVM PR34170 (crashes with inline asm with double output operand in GPR):
upstream review
+ finish patch and submit for upstream review
=== Plan for next week (week 12) ===
* (maybe) follow-up patch for PR34170 to also support case with several
output operands
* investigate failure to build clang in shared lib mode with gcc
o 1 post-connect day off
== Progress ==
o GNU Release transition
* Supported Mark for 2018.04 RCs
o LLVM
* Catching-up on devpt (TCWG-1286, ...)
* Benchmarking job for LLVM
* Buildbots babysitting
o Misc
* Various meetings and discussions.
* HK18 debriefing
