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ruby--ruby/test/ruby/test_rubyvm.rb
Kevin Newton 629908586b Finer-grained inline constant cache invalidation
Current behavior - caches depend on a global counter. All constant mutations cause caches to be invalidated.

```ruby
class A
  B = 1
end

def foo
  A::B # inline cache depends on global counter
end

foo # populate inline cache
foo # hit inline cache

C = 1 # global counter increments, all caches are invalidated

foo # misses inline cache due to `C = 1`
```

Proposed behavior - caches depend on name components. Only constant mutations with corresponding names will invalidate the cache.

```ruby
class A
  B = 1
end

def foo
  A::B # inline cache depends constants named "A" and "B"
end

foo # populate inline cache
foo # hit inline cache

C = 1 # caches that depend on the name "C" are invalidated

foo # hits inline cache because IC only depends on "A" and "B"
```

Examples of breaking the new cache:

```ruby
module C
  # Breaks `foo` cache because "A" constant is set and the cache in foo depends
  # on "A" and "B"
  class A; end
end

B = 1
```

We expect the new cache scheme to be invalidated less often because names aren't frequently reused. With the cache being invalidated less, we can rely on its stability more to keep our constant references fast and reduce the need to throw away generated code in YJIT.
2022-03-24 09:14:38 -07:00

73 lines
1.5 KiB
Ruby

# frozen_string_literal: false
require 'test/unit'
class TestRubyVM < Test::Unit::TestCase
def test_stat
assert_kind_of Hash, RubyVM.stat
assert_kind_of Integer, RubyVM.stat[:class_serial]
RubyVM.stat(stat = {})
assert_not_empty stat
assert_equal stat[:class_serial], RubyVM.stat(:class_serial)
end
def test_stat_unknown
assert_raise(ArgumentError){ RubyVM.stat(:unknown) }
assert_raise_with_message(ArgumentError, /\u{30eb 30d3 30fc}/) {RubyVM.stat(:"\u{30eb 30d3 30fc}")}
end
def parse_and_compile
script = <<~RUBY
_a = 1
def foo
_b = 2
end
1.times{
_c = 3
}
RUBY
ast = RubyVM::AbstractSyntaxTree.parse(script)
iseq = RubyVM::InstructionSequence.compile(script)
[ast, iseq]
end
def test_keep_script_lines
pend if ENV['RUBY_ISEQ_DUMP_DEBUG'] # TODO
prev_conf = RubyVM.keep_script_lines
# keep
RubyVM.keep_script_lines = true
ast, iseq = *parse_and_compile
lines = ast.script_lines
assert_equal Array, lines.class
lines = iseq.script_lines
assert_equal Array, lines.class
iseq.each_child{|child|
assert_equal lines, child.script_lines
}
assert lines.frozen?
# don't keep
RubyVM.keep_script_lines = false
ast, iseq = *parse_and_compile
lines = ast.script_lines
assert_equal nil, lines
lines = iseq.script_lines
assert_equal nil, lines
iseq.each_child{|child|
assert_equal lines, child.script_lines
}
ensure
RubyVM.keep_script_lines = prev_conf
end
end