RFR: 8285868: x86_64 intrinsics for floating point methods isNaN, isFinite and isInfinite [v8]

[Jatin Bhateja]

On Thu, 19 May 2022 04:27:11 GMT, Srinivas Vamsi Parasa <duke at openjdk.java.net> wrote:

> * Zeroing the register before `setb` instruction, referring to the same section
>   > For optimal performance, use of zero idioms, before the use of the register, eliminates the need for partial register
>   > merge micro-ops
>   
>   
>   This is more preferable since it does not contribute an execution uop in the backend (but still consumes a slot in the
>   decoder and uop cache)

Agree.  even a prior, movl REG, 0 can be used, it never reaches execution ports.

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PR: https://git.openjdk.java.net/jdk/pull/8459