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authorAlan Wu <XrXr@users.noreply.github.com>2019-07-30 21:36:05 -0400
committer卜部昌平 <shyouhei@ruby-lang.org>2019-10-24 18:03:42 +0900
commit89e7997622038f82115f34dbb4ea382e02bed163 (patch)
tree993a5f6fb17418381e835be1fd51093dc620148a /dln.h
parent38e931fa2ceac6d922f3eabedb8f35f211de0bdb (diff)
downloadruby-89e7997622038f82115f34dbb4ea382e02bed163.tar.gz
Combine call info and cache to speed up method invocation
To perform a regular method call, the VM needs two structs, `rb_call_info` and `rb_call_cache`. At the moment, we allocate these two structures in separate buffers. In the worst case, the CPU needs to read 4 cache lines to complete a method call. Putting the two structures together reduces the maximum number of cache line reads to 2. Combining the structures also saves 8 bytes per call site as the current layout uses separate two pointers for the call info and the call cache. This saves about 2 MiB on Discourse. This change improves the Optcarrot benchmark at least 3%. For more details, see attached bugs.ruby-lang.org ticket. Complications: - A new instruction attribute `comptime_sp_inc` is introduced to calculate SP increase at compile time without using call caches. At compile time, a `TS_CALLDATA` operand points to a call info struct, but at runtime, the same operand points to a call data struct. Instruction that explicitly define `sp_inc` also need to define `comptime_sp_inc`. - MJIT code for copying call cache becomes slightly more complicated. - This changes the bytecode format, which might break existing tools. [Misc #16258]
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