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Combine call info and cache to speed up method invocation

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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]
This commit is contained in:
Alan Wu 2019-07-30 21:36:05 -04:00 • committed by 卜部昌平
parent 38e931fa2c
commit 89e7997622
Notes: git 2019-10-24 18:04:08 +09:00
17 changed files with 322 additions and 264 deletions
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19
tool/ruby_vm/models/attribute.rb
View file

@ -21,6 +21,13 @@ class RubyVM::Attribute
@key = opts[:name]
@expr = RubyVM::CExpr.new location: opts[:location], expr: opts[:expr]
@type = opts[:type]
@ope_decls = @insn.opes.map do |operand|
decl = operand[:decl]
if @key == 'comptime_sp_inc' && operand[:type] == 'CALL_DATA'
decl = decl.gsub('CALL_DATA', 'CALL_INFO').gsub('cd', 'ci')
end
decl
end
end
def name
@ -32,22 +39,20 @@ class RubyVM::Attribute
end
def declaration
opes = @insn.opes
if opes.empty?
if @ope_decls.empty?
argv = "void"
else
argv = opes.map {|o| o[:decl] }.join(', ')
argv = @ope_decls.join(', ')
end
sprintf '%s %s(%s)', @type, name, argv
end
def definition
opes = @insn.opes
if opes.empty?
if @ope_decls.empty?
argv = "void"
else
argv = opes.map {|o| "MAYBE_UNUSED(#{o[:decl]})" }.join(",\n ")
argv = "\n #{argv}\n" if opes.size > 1
argv = @ope_decls.map {|decl| "MAYBE_UNUSED(#{decl})" }.join(",\n ")
argv = "\n #{argv}\n" if @ope_decls.size > 1
end
sprintf "%s\n%s(%s)", @type, name, argv
end