[llvm] r354746 - [CGP] add special-cases to form unsigned add with overflow (PR40486)

[Jordan Rupprecht via llvm-commits]

Thanks! That fix seems to resolve the crash on the non-reduced code.

The original code does not have -Wreturn-type warnings, so it's a
creduce artifact. But if I add "return 0" or make the methods return
void to silence those warnings, the crashes don't reproduce. I'll see
if I can tweak creduce to give something that crashes *without*
warnings, and that might shed some more light on the crash.

On Mon, Mar 4, 2019 at 2:55 PM Sanjay Patel <spatel at rotateright.com> wrote:
>
> Should be fixed here:
> https://reviews.llvm.org/rL355345
> ...but it's disturbing that we're in this situation at all with optimizations on. I don't know much about the new pass manager, but this doesn't happen with the old pass manager because the IR isn't so full of bogus values.
>
> On Mon, Mar 4, 2019 at 2:07 PM Sanjay Patel <spatel at rotateright.com> wrote:
>>
>> Taking a look now...not sure if this is just an artifact of the reduction, but I see 4 of these:
>> repro.cc:188:3: warning: control reaches end of non-void function [-Wreturn-type]
>>
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