RFR: 8291466: C2: assert(false) failed: infinite loop in PhaseIterGVN::transform_old with -XX:+StressIGVN

[Roland Westrelin]

On Thu, 25 Aug 2022 00:47:06 GMT, Pengfei Li <pli at openjdk.org> wrote:

>> src/hotspot/share/opto/mulnode.cpp line 252:
>> 
>>> 250: 
>>> 251:   // Now we have a constant Node on the right and the constant in con
>>> 252:   if (con == 0) return NULL;   // By zero is handled by Value call
>> 
>> Value() runs after Ideal so why wouldn't we have con == 0 here?
>
> This Ideal function is returned in `if ((con = in(2)->find_int_con(0)) == 0)` block above if we have `con == 0`. So this line is actually unreachable.

Ok. Can you reword the comment to state that explicitly?

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PR: https://git.openjdk.org/jdk/pull/9820