RFR: 8261137: Optimization of Box nodes in uncommon_trap [v6]

[Vladimir Kozlov]

On Wed, 10 Mar 2021 18:20:16 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> I just hit bug where VectorReinterpretTest.java test run with -XX:-DoEscapeAnalysis but Vector API generates SafePointScalarObjectNode regardless that:
> https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/vector.cpp#L249
> 
> But during deoptimization we only restore allocations when DoEscapeAnalysis is true:
> https://github.com/openjdk/jdk/blob/master/src/hotspot/share/runtime/deoptimization.cpp#L377
> 
> (currently condition is always true because jvmci_enabled == true since JVMCI included into build but without JVMCI it will fail as I found).
> 
> It seems with this change you need to add EliminateAutoBox flag check to deoptimization condition.
> Or guard your optimization with C->do_escape_analysis().
> 
> @iwanowww Do you think we should add checks for EnableVectorAggressiveReboxing and EliminateAutoBox into deoptimization code or guard Vector API code and this optimization with C->do_escape_analysis()?

The issue was fixed: 8263125. https://git.openjdk.java.net/jdk/pull/2924

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PR: https://git.openjdk.java.net/jdk/pull/2401