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Rinline: An inline expansion
optimizar for Ruby
RubyちこくKaigi
22nd, May. 2019
https://drecom.connpass.com/event/128107/
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Agenda
I created an optimizer for Ruby with inline expansion.
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Agenda
● What is inline expansion
● What is Rinline
● How Rinline works
● The future of Rinline
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What is inline expansion
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What is inline expansion
● Replacing method call with body of the called
method.
● It reduce overhead of method call.
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Inline expansion example
# Before
def foo
bar
end
def bar
puts 42
end
# After
def foo
puts 42
end
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Benchmark
● `m + n` vs `1 + 2`
○ def m() 1 end; def n() 2 end
● `m + n`: 5.71s
○ x1.56 slower
● `1 + 2`: 3.66s
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What is Rinline
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Rinline
● Rinline is a PoC of inline expansion optimizer for
Ruby
● https://github.com/pocke/rinline
● It makes Ruby faster!
○ (I hope)
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Usage
Rinline.optimize do |r|
r.optimize_instance_method(Klass, :method_name)
end
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DEMO
See
https://github.com/pocke/rinline/blob/master/benchma
rk/simple.rb
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How Rinline works
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Data flow
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Data flow
● Method name → UnboundMethod →
RubyVM::AST::Node → String of code → Inline
expanded code → Ruby program by eval
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Data flow example
def foo
bar
end
def bar
1
end
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Method name → UnboundMethod
● Use Module#instance_method
m = Klass.instance_method(:foo)
# => #
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UnboundMethod → RubyVM::AST::Node
● Use RubyVM::AST.of
node = RubyVM::AbstractSyntaxTree.of(m)
# =>
#
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RubyVM::AST::Node → String of Code
● RubyVM::AST::Node#to_source
○ It defined by AstExt (refinements patch)
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RubyVM::AST::Node → String of Code
● Use File.binread
path = m.source_location[0]
range = node.first_index..node.last_index
source = File.binread(path)[range]
# => “def foo() bar() end”
note: first|last_index are defined here
https://github.com/pocke/rinline/blob/2cb6ffb055c619998973f5bd2a349fcb6599e95c/lib/rinline/ext/ast_ext.rb#L144-L161
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String of code → Inline expanded code
● Replacing method call with called method body
● I will talk it on the next section!
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Inline expanded code → Ruby program by eval
● Use class_eval
Object.class_eval(inline_expanded_code)
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Replacing method
call
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Method call in Ruby
● FCALL → method call with arguments
■ foo(1, 2)
● VCALL → method call without arguments
■ foo
● CALL → method call with receiver
■ x.foo
● OPCALL → method call with operator
■ foo + bar
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Rinline supports FCALL and VCALL
● Easy to support (Supporting CALL is difficult)
○ CALL has a receiver, and receiver klass is
unknown statically in most cases
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How to replace
● RubyVM::AST::Node → … → Replaced code
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How to replace
● RubyVM::AST::Node → VCALL/FCALL Node →
UnboundMethod → RubyVM::AST::Node → String of
called method → lvar renamed code → Replaced
code
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Example
def foo
x = 1
bar
p x * 3
end
def bar
x = 21
p x * 2
end
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RubyVM::AST::Node → VCALL/FCALL Node
● Traverse
● Find VCALL / FCALL
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Traverse
def traverse(&block)
block.call(self)
children.each do |c|
c.traverse(&block) if c.is_a?(RubyVM::AST::Node)
end
end
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Find VCALL / FCALL
def foo
x = 1
bar # ← VCALL node
p x * 3
end
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VCALL/FCALL Node → UnboundMethod →
Method definition Node
method_name = vcall_node.children[0] # => :bar
method = Klass.instance_method(method_name)
method_def_node = RubyVM::AST.of(method)
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RubyVM::AST::Node → String of called method
def_src = method_def_node.to_source
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String of called method → lvar renamed code
● Before embed, renaming lvar is needed
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Example
def foo
x = 1
bar
p x * 3 # => 3
end
def bar
x = 21
p x * 2 # => 42
end
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Example: It will be break!
def foo
x = 1
x = 21
p x * 2 # => 42
p x * 3 # => 63
end
def bar
x = 21
p x * 2
end
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Fix local var collision
def foo
x = 1
x_XXX = 21
p x_XXX * 2 # => 42
p x * 3 # => 3
end
def bar
x = 21
p x * 2
end
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lvar renamed code → Replaced code
def foo
x = 1
x_XXX = 21
p x_XXX * 2
p x * 3
end
It is ok, but actually the
replaced code will be
enclosed with double
braces
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lvar renamed code → Replaced code
def foo
x = 1
((x_XXX = 21
p x_XXX * 2))
p x * 3
end
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Why braces
bar * 3 # => 9 def bar
1 + 2
end
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Why braces
bar * 3 # => 9
1 + 2 * 3 # => 7
(1 + 2) * 3 # => 9
def bar
1 + 2
end
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Why double braces
p bar def bar
1; 2
end
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Why double braces
p (1; 2)
# => SyntaxError!
p ((1; 2))
# => Valid
def bar
1; 2
end
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The future of Rinline
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Meaningful optimization
● Currently it makes micro benchmark faster
● But it does not make actual app faster
○ For example, I tried to optimize optcarrot, but it
does not change the FPS
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Fix many bugs
● Rinline generates invalid code
○ For example: It breaks on define_method
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Support super
● Currently, Rinline just ignores `super` node
● It can support `super` with
UnboundMethod#super_method
○ https://twitter.com/udzura/status/11303947244
58565633
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Conclusion
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Conclusion
● RubyVM::AST.of is useful for “Dark Power”
● Rinline is a PoC of inline expansion for Ruby
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pp self
● Masataka “pocke” Kuwabara
● Work for Bit Journey, Inc.
Thank you for listening!