[aarch64-port-dev ] Query regarding maybe_isb() introduced into jdk8

[Andrew Dinn]

I am looking at the following jdk8 aarch64 changeset:

Changeset: 7220
Branch: default
User: aph
Date: Mon Sep 01 18:10:18 BST 2014

This introduces a load of isb() calls into various bits of generated
code via a new assembler method maybe_isb(). I don't understand why
these calls are needed in /any/ case (never mind in all). Especially
mysterious are the likes of

   __ reset_last_Java_frame(false, true);

+  __ maybe_isb();
+

which happens at line 2813 of sharedRuntime_)aarch64.cpp

How does setting fields in the thread anchor to NULL impose the need to
update the instruction cache? Can anyone explain this code?

regards,


Andrew Dinn
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