ruby/yjit.rb

module YJIT
  if defined?(Disasm)
    def self.disasm(iseq, tty: $stdout && $stdout.tty?)
      iseq = RubyVM::InstructionSequence.of(iseq)

      blocks = YJIT.blocks_for(iseq)
      return if blocks.empty?

      str = String.new
      str << iseq.disasm
      str << "\n"

      # Sort the blocks by increasing addresses
      sorted_blocks = blocks.sort_by(&:address)

      highlight = ->(str) {
        if tty
          "\x1b[1m#{str}\x1b[0m"
        else
          str
        end
      }

      cs = YJIT::Disasm.new
      sorted_blocks.each_with_index do |block, i|
        str << "== BLOCK #{i+1}/#{blocks.length}: #{block.code.length} BYTES, ISEQ RANGE [#{block.iseq_start_index},#{block.iseq_end_index}) ".ljust(80, "=")
        str << "\n"

        comments = comments_for(block.address, block.address + block.code.length)
        comment_idx = 0
        cs.disasm(block.code, block.address).each do |i|
          while (comment = comments[comment_idx]) && comment.address <= i.address
            str << "  ; #{highlight.call(comment.comment)}\n"
            comment_idx += 1
          end

          str << sprintf(
            "  %<address>08x:  %<instruction>s\t%<details>s\n",
            address: i.address,
            instruction: i.mnemonic,
            details: i.op_str
          )
        end
      end

      block_sizes = blocks.map { |block| block.code.length }
      total_bytes = block_sizes.sum
      str << "\n"
      str << "Total code size: #{total_bytes} bytes"
      str << "\n"

      str
    end

    def self.comments_for(start_address, end_address)
      Primitive.comments_for(start_address, end_address)
    end
  end

  # Return a hash for statistics generated for the --yjit-stats command line option.
  # Return nil when option is not passed or unavailable.
  def self.runtime_stats
    # defined in yjit_iface.c
    Primitive.get_stat_counters
  end

  # Discard statistics collected for --yjit-stats.
  def self.reset_stats!
    # defined in yjit_iface.c
    Primitive.reset_stats_bang
  end

  class << self
    private

    # Format and print out counters
    def _print_stats
      counters = runtime_stats
      return unless counters

      $stderr.puts("***YJIT: Printing runtime counters from yjit.rb***")
      $stderr.puts("Number of bindings allocated: %d\n" % counters[:binding_allocations])
      $stderr.puts("Number of locals modified through binding: %d\n" % counters[:binding_set])

      print_counters(counters, prefix: 'send_', prompt: 'method call exit reasons: ')
      print_counters(counters, prefix: 'leave_', prompt: 'leave exit reasons: ')
      print_counters(counters, prefix: 'getivar_', prompt: 'getinstancevariable exit reasons:')
      print_counters(counters, prefix: 'setivar_', prompt: 'setinstancevariable exit reasons:')
      print_counters(counters, prefix: 'oaref_', prompt: 'opt_aref exit reasons: ')
    end

    def print_counters(counters, prefix:, prompt:)
      $stderr.puts(prompt)
      counters = counters.filter { |key, _| key.start_with?(prefix) }
      counters.filter! { |_, value| value != 0 }
      counters.transform_keys! { |key| key.to_s.delete_prefix(prefix) }

      if counters.empty?
        $stderr.puts("    (all relevant counters are zero)")
        return
      end

      counters = counters.to_a
      counters.sort_by! { |(_, counter_value)| counter_value }
      longest_name_length = counters.max_by { |(name, _)| name.length }.first.length
      total = counters.sum { |(_, counter_value)| counter_value }

      counters.reverse_each do |(name, value)|
        percentage = value.fdiv(total) * 100
        $stderr.printf("    %*s %10d (%4.1f%%)\n", longest_name_length, name, value, percentage);
      end
    end
  end
end