RFR: 8269476: Skip nmethod entry barrier if there is no oops in the jit code [v2]

[王超]

On Mon, 28 Jun 2021 12:11:48 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:

> I think there is a simpler way to accomplish this by playing with disarmed_value, e.g. setting nmethod's disarmed_value to certain pattern to indicate it is always disarmed.

`__ cmpl(disarmed_addr, 0);` will only set ZF=1 when `dest = source`. By playing with disarmed_value, do you mean also change the cmpl instruction to other instruction?

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PR: https://git.openjdk.java.net/jdk/pull/4610