[14] RFR(M): 8229496: SIGFPE (division by zero) in C2 OSR compiled method

[Doerr, Martin]

Hi Tobias,

thanks for fixing this issues.

I haven't found any mistakes in your change so far, but a few things are unclear to me.

I thought we were using implicit div by zero checks on x86 (SIGFPE gets caught in signal handler on AMD64). So was the continuation_for_implicit_div0_exception not found in ImplicitExceptionTable? Or why did the VM crash?

I wonder if it's fine to use "if (lo1 >= 0) lo = 0" in the CastIINode / CastLLNode. Shouldn't lo > 0 stay valid?
(Also in the existing CastIINode, but your usage is new.)

This issue sounds a little bit similar to 
https://bugs.openjdk.java.net/browse/JDK-8220376
but I guess there's more work to be done for that.

Thanks and best regards,
Martin


> -----Original Message-----
> From: hotspot-compiler-dev <hotspot-compiler-dev-
> bounces at openjdk.java.net> On Behalf Of Tobias Hartmann
> Sent: Montag, 2. September 2019 07:56
> To: Roland Westrelin <rwestrel at redhat.com>; hotspot compiler <hotspot-
> compiler-dev at openjdk.java.net>
> Subject: Re: [14] RFR(M): 8229496: SIGFPE (division by zero) in C2 OSR
> compiled method
> 
> 
> On 30.08.19 08:36, Tobias Hartmann wrote:
> >> Have you verified performance?
> > Not yet, I wanted to wait for reviews. But I'll submit testing over the
> weekend.
> 
> All benchmarks finished, there is no performance difference.
> 
> Anyone up for a second review?
> 
> Thanks,
> Tobias