r310401 - PR19668, PR23034: Fix handling of move constructors and deleted copy

[Richard Smith via cfe-commits]

On 15 August 2017 at 08:56, Diana Picus via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> Ugh, I'm not sure that last email made it through.
>
> Here's the IR with -Xclang -disable-llvm-passes, at r310400 and r310401:
> https://goo.gl/4n84SR
> https://goo.gl/gxhxp9
>
> The diff between them is small enough so I don't think there's much
> point in reducing it further.
> Hope that helps.


Yes, that helps a lot. The problem was that the implicitly-generated
va_list struct for ARM wasn't getting the "CanPassInRegisters" flag set,
and got passed indirectly (contrary to the ABI).

I've added a test for that kind of problem in r310982, and re-committed the
patch as r310983.

Thanks for all your assistance here!


> On 15 August 2017 at 17:51, Diana Picus <diana.picus at linaro.org> wrote:
> > Actually, I'm not sure I need to reduce it, the diff between the IR
> > with -Xclang -no-llvm-passes is pretty small for the version
> > with/without the patch. See attached. I hope this helps, it does look
> > like a problem with va_arg handling.
> >
> > Sorry again that this is going so slowly...
> >
> > On 15 August 2017 at 16:52, Diana Picus <diana.picus at linaro.org> wrote:
> >> On 15 August 2017 at 01:25, Richard Smith <richard at metafoo.co.uk>
> wrote:
> >>> On 14 August 2017 at 03:27, Diana Picus via cfe-commits
> >>> <cfe-commits at lists.llvm.org> wrote:
> >>>>
> >>>> Hi,
> >>>>
> >>>> Strangely enough, it turns out that if I run
> >>>> Asan-armhf-with-calls-Noinst-Test on the command line it fails,
> >>>> although it doesn't fail when run with lit.
> >>>
> >>>
> >>> Looks like the crash is within the "use_colors == true" portion of
> >>> ColoredPrintf, so this would make sense if running the test within lit
> turns
> >>> off color support (perhaps because the output is not a terminal).
> >>>
> >>
> >> That's a good catch, it seems if I run it with --gtest-color=no it
> >> still passes, but prints some garbage at the end:
> >> [ PASSED ] 97 tests.
> >> YOU HAVE -1094542056 DISABLED F]�뀼��_8�pG����D2
> >>
> >>
> >>>>
> >>>> I've attached the stack
> >>>> trace from gdb. It looks like some trouble passing down va_arg
> >>>> parameters, but I haven't looked into too much details. The segfault
> >>>> happens when we try to do a   ldrb   r3, [r0, r1], with r1 set to 0 by
> >>>> the current function and r0 passed down from the caller. I'm not sure
> >>>> if this is the exact same problem as the other tests, but feel free to
> >>>> have a look at that code.
> >>>
> >>>
> >>> Have you tried running Asan-armhf-with-calls-Noinst-Test on the
> command line
> >>> without this patch applied? (It's possible that this is a pre-existing
> bug
> >>> in ARM varargs call lowering, and is unrelated to the bug we're trying
> to
> >>> track down. This code path performs an unrelated varargs call between a
> >>> va_start / va_end pair, which seems like quite a rare situation, and I
> could
> >>> easily believe there's something wrong with our lowering that allows
> some
> >>> portion of the outer va_list state to be clobbered in that scenario.)
> >>>
> >>
> >> It seems to work without the patch. I'm currently trying to reduce
> >> Asan-armhf-with-calls-Test and I'll get back to you with the IR or
> >> assembly files (whichever makes any difference).
> >>
> >>>> Meanwhile, I've removed some clutter from Asan-armhf-with-calls-Test
> >>>> (which is the original failure that we were seeing) and left only one
> >>>> failing test that seemed small enough. I'll try to look at the
> >>>> disassembly before/after the patch and maybe even run valgrind on it
> >>>> (running it on the original binary naturally takes forever).
> >>>>
> >>>> Let me know if there's anything else I could try. I can also send you
> >>>> disassembly or even LLVM IR for the Asan-armhf-with-calls-Noinst-Test
> >>>> if you think it helps.
> >>>>
> >>>> Cheers,
> >>>> Diana
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