RFR: 8290246: test fails "assert(init != __null) failed: initialization not found"

[Dean Long]

On Thu, 14 Jul 2022 18:09:49 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> CTW test (which compiles methods without running them - no profiling) failed when run with stress flag and particular RNG seed `-XX:+StressIGVN -XX:StressSeed=1743550013`. The failure is intermittent because of RNG.
> 
> The compiled method [BasicPopupMenuUI$BasicMenuKeyListener::menuKeyPressed()](https://github.com/openjdk/jdk/blob/master/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicPopupMenuUI.java#L331) has allocation in loop at line [L360](https://github.com/openjdk/jdk/blob/master/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicPopupMenuUI.java#L360) which is followed by call `item.isArmed()` at line L366. This call is not "linked" and uncommon trap is generated for it. As result the allocation result become un-used.
> Due to shuffling done with `StressIGVN` flag LoadRangeNode is processed after InitializeNode is removed from graph but AllocateArrayNode is not. We hit assert because of that.
> 
> The fix replaces the assert with check.
> 
> Tested with replay file from bug report. I was not able to reproduce failure with standalone test because it is hard to force LoadRangeNode processing at right time. I attached to bug report a test which work on.
> 
> Testing tier1-3,xcomp

src/hotspot/share/opto/callnode.cpp line 1633:

> 1631:       if (init == NULL) {
> 1632:         return NULL; // Return NULL if dead path
> 1633:       }

Can all callers deal with NULL?  It looks like GraphKit::array_ideal_length() will crash if make_ideal_length() returns NULL.

This fix looks different from what you proposed in the bug report:
> Or attach CastII(length) to Allocate node control projection if Initialize node is not present. As I said before we may have legal cases like that (as I remember when working on EA).

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PR: https://git.openjdk.org/jdk/pull/9497