RFR: 8340544: Optimize setLocalsFromArg

[Chen Liang]

On Fri, 20 Sep 2024 16:13:06 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> CheckLocal once, reduce redundant checkLocal, rewrite switch, reduce method size, codeSize is reduced from 367 to 263.
>
> src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java line 1069:
> 
>> 1067:                     localsSize += 2;
>> 1068:                 } else {
>> 1069:                     if (desc == CD_int || desc == CD_boolean || desc == CD_byte || desc == CD_char || desc == CD_short) {
> 
> An alternative would be `if (!desc.isPrimitive()) { .. } else if (desc == CD_float) { .. } else { /* INTEGER_TYPE */ }` - might be more compact at least.

I think wenshao is intentionally avoiding `isPrimitive` as it is slower; we can fix that later I guess.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21106#discussion_r1768891745