On Mon, 15 Apr 2024 03:24:07 GMT, Vladimir Kozlov <k...@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. > > Vladimir Kozlov has updated the pull request incrementally with one > additional commit since the last revision: > > Union fields which usages do not overlap src/hotspot/share/code/nmethod.cpp line 1441: > 1439: int deps_size = align_up((int)dependencies->size_in_bytes(), > oopSize); > 1440: int sum_size = oops_size + metadata_size + deps_size; > 1441: assert((sum_size >> 16) == 0, "data size is bigger than 64Kb: %d", > sum_size); I suggest using checked_cast for the assignment below, rather than special-purpose checks here. src/hotspot/share/code/nmethod.cpp line 1445: > 1443: _metadata_offset = (uint16_t)oops_size; > 1444: _dependencies_offset = _metadata_offset + > (uint16_t)metadata_size; > 1445: _scopes_pcs_offset = _dependencies_offset + (uint16_t)deps_size; Use checked_cast instead of raw casts. src/hotspot/share/code/nmethod.cpp line 1459: > 1457: assert((data_offset() + data_end_offset) <= nmethod_size, "wrong > nmethod's size: %d < %d", nmethod_size, (data_offset() + data_end_offset)); > 1458: > 1459: _entry_offset = > (uint16_t)offsets->value(CodeOffsets::Entry); Use checked_cast. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/18768#discussion_r1566771026 PR Review Comment: https://git.openjdk.org/jdk/pull/18768#discussion_r1566772567 PR Review Comment: https://git.openjdk.org/jdk/pull/18768#discussion_r1566773477
