[llvm-dev] Critical XRay fixes for Arm32

[Serge Rogatch via llvm-dev]

Thank you for considering.
Dean, Renato - what do you think?

On 26 January 2017 at 22:54, Hans Wennborg <hans at chromium.org> wrote:

> I see. Thanks for clarifying.
>
> I'm Ok with merging these if Dean agrees, as I believe he's the code owner.
>
> Thanks,
> Hans
>
> On Thu, Jan 26, 2017 at 11:47 AM, Serge Rogatch <serge.rogatch at gmail.com>
> wrote:
> > There were no LLVM tests for presence of XRay instrumentation map in the
> > emitted assembly. You can see that https://reviews.llvm.org/D28624 adds
> this
> > check to the tests.
> > The tests in compiler-rt had been accidentally disabled.
> > https://reviews.llvm.org/D28623 enables them in
> > compiler-rt/test/xray/lit.cfg .
> >
> > On 26 January 2017 at 22:37, Hans Wennborg <hans at chromium.org> wrote:
> >>
> >> I'm wondering why the lit tests didn't catch this as part of testing rc1
> >> on ARM.
> >>
> >> On Thu, Jan 26, 2017 at 11:25 AM, Serge Rogatch <
> serge.rogatch at gmail.com>
> >> wrote:
> >> > XRay is tested automatically on build-bots with tests in LLVM and
> >> > compiler-rt . Or are you asking for manual testing instructions?
> >> > Of these 2 patches, the compiler-rt patch depends on LLVM patch
> because
> >> > the
> >> > tests compiler-rt\test\xray\TestCases\Linux would fail without the
> fix
> >> > in
> >> > LLVM. The compiler-rt patch also enables the tests which were
> >> > occasionally
> >> > disabled.
> >> >
> >> > The XRay feature is quite isolated, so side-effects are not expected.
> I
> >> > can
> >> > only see a risk that some commit I took for granted when
> making&testing
> >> > the
> >> > fixes, somehow didn't get to 4.0 branch.
> >> >
> >> >
> >> > On 26 January 2017 at 21:44, Hans Wennborg <hans at chromium.org> wrote:
> >> >>
> >> >> How is XRay tested? IIRC, Renato didn't see any test failures on ARM?
> >> >>
> >> >> Merging sounds reasonbaly, I'd just like to understand what's the
> risk
> >> >> for the branch.
> >> >>
> >> >> On Thu, Jan 26, 2017 at 10:29 AM, Serge Rogatch
> >> >> <serge.rogatch at gmail.com>
> >> >> wrote:
> >> >> > Hans, these changes reached trunk in
> >> >> > https://reviews.llvm.org/rL292516
> >> >> > and
> >> >> > https://reviews.llvm.org/rL292517 . Could you look?
> >> >> >
> >> >> > On 26 January 2017 at 03:29, Serge Rogatch <
> serge.rogatch at gmail.com>
> >> >> > wrote:
> >> >> >>
> >> >> >> Sorry, I initially included LLVM-Commits rather than LLVM-Dev.
> >> >> >> Fixed.
> >> >> >>
> >> >> >> On 26 January 2017 at 03:26, Serge Rogatch <
> serge.rogatch at gmail.com>
> >> >> >> wrote:
> >> >> >>>
> >> >> >>> Hi Dean, Renato,
> >> >> >>>
> >> >> >>> AFAIK, unfortunately, these critical Arm32 XRay fixes are not yet
> >> >> >>> in
> >> >> >>> 4.0:
> >> >> >>> https://reviews.llvm.org/D28624 , https://reviews.llvm.org/
> D28623 .
> >> >> >>> The
> >> >> >>> first repairs XRay instrumentation map emission. Without this map
> >> >> >>> XRay
> >> >> >>> doesn't work at all: the runtime doesn't see anything to
> >> >> >>> instrument.
> >> >> >>> The
> >> >> >>> second fixes the CPU cache incoherency problem. Without this
> patch,
> >> >> >>> XRay
> >> >> >>> will intermittently fail to patch or unpatch some sleds
> (depending
> >> >> >>> on
> >> >> >>> whether their code is in CPU cache or not).
> >> >> >>>
> >> >> >>> Is there any chance we can get these patches to 4.0? This page
> >> >> >>> http://llvm.org/docs/HowToReleaseLLVM.html#release-patch-rules
> says
> >> >> >>> that
> >> >> >>> "release manager, the official release testers or the code
> owners"
> >> >> >>> may
> >> >> >>> approve cherry-picking to release branch from trunk. AFAIK, you
> are
> >> >> >>> code
> >> >> >>> owners for XRay and ARM. I don't know who are the release manager
> >> >> >>> or
> >> >> >>> official release testers.
> >> >> >>>
> >> >> >>> Cheers,
> >> >> >>> Serge
> >> >> >>
> >> >> >>
> >> >> >
> >> >
> >> >
> >
> >
>
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