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 240 bytes. From 304 to 256 in optimized VM:
Statistics for 1282 bytecoded nmethods for C2: total in heap = 5560352 (100%) header = 389728 (7.009053%) vs Statistics for 1298 bytecoded nmethods for C2: total in heap = 5766040 (100%) header = 332288 (5.762846%) 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. ------------- Commit messages: - 8329433: Reduce nmethod header size Changes: https://git.openjdk.org/jdk/pull/18768/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18768&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8329433 Stats: 386 lines in 15 files changed: 92 ins; 115 del; 179 mod Patch: https://git.openjdk.org/jdk/pull/18768.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/18768/head:pull/18768 PR: https://git.openjdk.org/jdk/pull/18768
