[LLVMdev] Newbee question: LLVM backend regression tests for thumb1 targets on simulator possible?

[Eric Christopher]

On Wed Dec 17 2014 at 10:51:51 AM Kristof Beyls <kristof.beyls at arm.com>
wrote:

> I've been wondering too about how to get better ARM v6m compile-and-execute
> testing going.
>
> As you say Jon, the non-execution-based regression tests are surprisingly
> good at catching issues; but they're no full substitute for executing the
> code produced by the backend for a reasonably-sized test suite.
>
> If somehow it would be possible to compile and run the LLVM test-suite
> for v6m, I think that would be a good step forward. It would also allow
> to get a buildbot going without too much effort continuously checking
> basic correctness of v6m code generation.
>
> My guess is that the biggest hurdle would be to get linux or a similar
> operating system going on a v6m/thumb1 simulator. Does anyone have an idea
> if this is feasible or completely impossible?
>
>
Not sure feasibility of the particular implementation, but qemu + linux
works pretty well for testing other targets.

-eric


> Thanks,
>
> Kristof
>
> > -----Original Message-----
> > From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
> > On Behalf Of Jonathan Roelofs
> > Sent: 15 December 2014 18:31
> > To: Bjoern Haase; llvmdev at cs.uiuc.edu
> > Subject: Re: [LLVMdev] Newbee question: LLVM backend regression tests
> > for thumb1 targets on simulator possible?
> >
> >
> >
> > On 12/15/14 4:29 AM, Bjoern Haase wrote:
> > >
> > > Hello,
> > >
> > > as a newbee, I'd appreciate some support on regression test setup.
> > >
> > > Specifically, I am interrested in the feature of tail call
> > > optimizations for the ARM v6m targets. This feature currently seems to
> > > be completely deactivated at the moment (v6m being based on thumb1
> > > ?!). According to my code-reading, this feature will involve some
> > > modifications in epilogue generation.
> > >
> > > My work on a gcc backend did show me that for a beginner like me, it
> > > is rather likely that the first attempts will break something.
> > :)
> > >
> > > Thus, being completely new to the llvm project I think that it's
> > > essential to first establish a suitable regression test setup. My plan
> > > is to run the tests for the v4t platform in thumb-only mode where free
> > > simulators are available and which behaves (at least with respect to
> > > the
> > > epilogue) very much like v6m.
> > Why not test your v6m changes on a Cortex-m0 QEMU? Semihosted
> > applications are pretty easy to get going, something like:
> >
> > $ qemu-system-arm -semihosting -M integratorcp -cpu cortex-m0 -kernel
> > a.out
> >
> > Thumv4t support is a bit spotty in llvm as it's not very well tested.
> > The problem I run into most (and fixed several times), is that thumbv4t
> > doesn't have a lo->lo mov instruction that doesn't clobber cpsr. That
> > being said, it does work for the most part... just something to watch
> > out for.
> > >
> > >  From former work on gcc I'm used to the possibilty to run regression
> > > tests in a simulator for the target platform (there with the expect
> > > script mechanism). In the documentation on the web, I did, however,
> > > not yet find information on a comparable feature for llvm.
> > >
> > > Therefore the specific questions:
> > >
> > > - Is there a mechanism to run backend testsuite runs in a simulation
> > > framework and if yes, could you give me a hint on how to find
> > > information
> > Not that I know of, no.
> >
> > I routinely run the libc++ & libc++abi test suites in QEMU, but that's
> > more of a whole-toolchain test, rather that just a backend test. You can
> > get surprisingly far without simulator testing, so for most things, LLVM
> > doesn't use it for testing. This makes it easier for any random
> > developer to check out the llvm sources, build them, and run the
> > testsuite, and not have to have simulators installed for all the
> > different backends.
> > > - If not, how is regression testing for the thumb1 targets currently
> > > implemented?
> > We use the LIT framework http://llvm.org/docs/CommandGuide/lit.html to
> > test the compiler. Mostly this means feeding in llvm IR, and using
> > FileCheck http://llvm.org/docs/CommandGuide/FileCheck.html (which is
> > basically a glorified
> > grep) to verify that the assembly produced is the same as what the test
> > expects to be generated.
> >
> > To run these tests, use the 'make check-all' target from the build
> > directory.
> >
> >
> > Cheers,
> >
> > Jon
> > >
> > > Yours,
> > >
> > > Björn Haase
> > >
> > > P.S.: Of course, any hint with respect to sibling call optimization
> > > would also be appreciated in a second step. I actually already found
> > > some helpful information in the sources.
> > >
> > > _______________________________________________
> > > LLVM Developers mailing list
> > > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
> > --
> > Jon Roelofs
> > jonathan at codesourcery.com
> > CodeSourcery / Mentor Embedded
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20141217/8a5f547e/attachment.html>