On Fri, 26 Apr 2024 21:16:03 GMT, Vladimir Kozlov <[email protected]> wrote:
> Move immutable nmethod's data from CodeCache to C heap. It includes
> `dependencies, nul_chk_table, handler_table, scopes_pcs, scopes_data,
> speculations, jvmci_data`. It amounts for about 30% (optimized VM) of space
> in CodeCache.
>
> Use HotSpot's `os::malloc()` to allocate memory in C heap for immutable
> nmethod's data. Bail out compilation if allocation failed.
>
> Shuffle fields order and change some fields size from 4 to 2 bytes to avoid
> nmethod's header size increase.
>
> Tested tier1-5, stress,xcomp
>
> Our performance testing does not show difference.
>
> Example of updated `-XX:+PrintNMethodStatistics` output is in JBS comment.
src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/code/NMethod.java line 528:
> 526: private int getScopesDataOffset() { return (int)
> scopesDataOffsetField .getValue(addr); }
> 527: private int getScopesPCsOffset() { return (int)
> scopesPCsOffsetField .getValue(addr); }
> 528: private int getDependenciesOffset() { return (int) 0; }
Suggestion:
No longer used.
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PR Review Comment: https://git.openjdk.org/jdk/pull/18984#discussion_r1581671710
