[jdk18] RFR: 8278508: Enable X86 maskAll instruction pattern for 32 bit JVM. [v2]

[Jatin Bhateja]

On Tue, 21 Dec 2021 19:12:17 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> Hi, do we need `TEMP dst` if some `tmp` is used after `dst` is written, as without it `tmp` and `dst` are implied to have non-overlapping lifetime and can lead to conflict. This is a pure question unrelated to the PR. Thank you very much.
>
> Hi @merykitty, yes we would need TEMP dst in that case as well.

TEMP attribute ensures creation of a temporary machine operand which interferes with source operands if their registerclasses are overlapping, a TEMP + DST data flow attribute ensures that DST is not accidentally allocated a SRC register even if SRC is not live beyond that instruction. This shall prevent overriding the src before using its value in the instruction encoding block.

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PR: https://git.openjdk.java.net/jdk18/pull/24