Register output in assert case useful?

[Vladimir Kozlov]

Yes, please.

We try to print values for failed asserts but not in all places. To have values in registers would be good. Do you also dump "Instructions:" near assert code?

One thing to watch out is when debugging code (in debugger) there is ability to continue execution when assert is triggered:

http://hg.openjdk.java.net/jdk10/hs/file/068d316e905e/src/hotspot/share/utilities/debug.cpp#l209

This should be preserved.

Vladimir

On 10/26/17 6:37 AM, Thomas Stüfe wrote:
> Hi all,
> 
> when an assert happens, one does not have an ucontext_t and hence no
> register context - that is why hs-err files generated by an assert do not
> contain registers.
> 
> But sometimes there are cases where it would be useful to know the content
> of registers at assert - e.g. to know the current stack depth, or because
> remnants in registers may help with investigating.
> 
> At SAP we added a small feature to retrieve the current context when an
> assert happens and make that part of the hs-err file. Works similar to the
> SafeFetch logic: when an assert happens, we trigger a segfault and in the
> signal handler we squirrel the ucontext away, before continuing with error
> reporting. We do this right after the assert condition was evaluated, so
> this is as close to the assert point as possible (basically, just a read
> access which is part of the assert macro).
> 
> I wonder whether there is interest in us contributing this?
> 
> Kind Regards, Thomas
>