Integrated: 8329433: Reduce nmethod header size

[Vladimir Kozlov]

On Fri, 12 Apr 2024 22:43:15 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> This is part of changes which try to reduce size of `nmethod` and `codeblob` data vs code in CodeCache.
> These changes reduced size of `nmethod` header from 288 to 232 bytes. From 304 to 248 in optimized VM:
> 
> Statistics for 1282 bytecoded nmethods for C2:
>  total in heap = 5560352 (100%)
>  header = 389728 (7.009053%)
> 
> vs
> 
> Statistics for 1322 bytecoded nmethods for C2:
>  total in heap  = 8307120 (100%)
>  header         = 327856 (3.946687%)
> 
> 
> Several unneeded fields in `nmethod` and `CodeBlob` were removed. Some fields were changed from `int` to `int16_t` with added corresponding asserts to make sure their values are fit into 16 bits.
> 
> I did additional cleanup after recent `CompiledMethod` removal.
> 
> Tested tier1-7,stress,xcomp and performance testing.

This pull request has now been integrated.

Changeset: b704e912
Author:    Vladimir Kozlov <kvn at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/b704e91241b0f84d866f50a8f2c6af240087cb29
Stats:     523 lines in 15 files changed: 135 ins; 186 del; 202 mod

8329433: Reduce nmethod header size

Reviewed-by: dlong, iveresov

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PR: https://git.openjdk.org/jdk/pull/18768