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Diffstat (limited to 'yjit.rb')
| -rw-r--r-- | yjit.rb | 499 |
1 files changed, 499 insertions, 0 deletions
diff --git a/yjit.rb b/yjit.rb new file mode 100644 index 0000000000..eedd00c358 --- /dev/null +++ b/yjit.rb @@ -0,0 +1,499 @@ +# frozen_string_literal: true +# :markup: markdown + +# This module allows for introspection of \YJIT, CRuby's just-in-time compiler. +# Everything in the module is highly implementation specific and the API might +# be less stable compared to the standard library. +# +# This module may not exist if \YJIT does not support the particular platform +# for which CRuby is built. +module RubyVM::YJIT + # Check if \YJIT is enabled. + def self.enabled? + Primitive.cexpr! 'RBOOL(rb_yjit_enabled_p)' + end + + # Check if `--yjit-stats` is used. + def self.stats_enabled? + Primitive.rb_yjit_stats_enabled_p + end + + # Check if rb_yjit_trace_exit_locations_enabled_p is enabled. + def self.trace_exit_locations_enabled? # :nodoc: + Primitive.rb_yjit_trace_exit_locations_enabled_p + end + + # Discard statistics collected for `--yjit-stats`. + def self.reset_stats! + Primitive.rb_yjit_reset_stats_bang + end + + # Enable \YJIT compilation. `stats` option decides whether to enable \YJIT stats or not. + # + # * `false`: Disable stats. + # * `true`: Enable stats. Print stats at exit. + # * `:quiet`: Enable stats. Do not print stats at exit. + def self.enable(stats: false) + return false if enabled? + at_exit { print_and_dump_stats } if stats + Primitive.rb_yjit_enable(stats, stats != :quiet) + end + + # If --yjit-trace-exits is enabled parse the hashes from + # Primitive.rb_yjit_get_exit_locations into a format readable + # by Stackprof. This will allow us to find the exact location of a + # side exit in YJIT based on the instruction that is exiting. + def self.exit_locations # :nodoc: + return unless trace_exit_locations_enabled? + + results = Primitive.rb_yjit_get_exit_locations + raw_samples = results[:raw].dup + line_samples = results[:lines].dup + frames = results[:frames].dup + samples_count = 0 + + # Loop through the instructions and set the frame hash with the data. + # We use nonexistent.def for the file name, otherwise insns.def will be displayed + # and that information isn't useful in this context. + RubyVM::INSTRUCTION_NAMES.each_with_index do |name, frame_id| + frame_hash = { samples: 0, total_samples: 0, edges: {}, name: name, file: "nonexistent.def", line: nil, lines: {} } + results[:frames][frame_id] = frame_hash + frames[frame_id] = frame_hash + end + + # Loop through the raw_samples and build the hashes for StackProf. + # The loop is based off an example in the StackProf documentation and therefore + # this functionality can only work with that library. + # + # Raw Samples: + # [ length, frame1, frame2, frameN, ..., instruction, count + # + # Line Samples + # [ length, line_1, line_2, line_n, ..., dummy value, count + i = 0 + while i < raw_samples.length + stack_length = raw_samples[i] + i += 1 # consume the stack length + + sample_count = raw_samples[i + stack_length] + + prev_frame_id = nil + stack_length.times do |idx| + idx += i + frame_id = raw_samples[idx] + + if prev_frame_id + prev_frame = frames[prev_frame_id] + prev_frame[:edges][frame_id] ||= 0 + prev_frame[:edges][frame_id] += sample_count + end + + frame_info = frames[frame_id] + frame_info[:total_samples] += sample_count + + frame_info[:lines][line_samples[idx]] ||= [0, 0] + frame_info[:lines][line_samples[idx]][0] += sample_count + + prev_frame_id = frame_id + end + + i += stack_length # consume the stack + + top_frame_id = prev_frame_id + top_frame_line = 1 + + frames[top_frame_id][:samples] += sample_count + frames[top_frame_id][:lines] ||= {} + frames[top_frame_id][:lines][top_frame_line] ||= [0, 0] + frames[top_frame_id][:lines][top_frame_line][1] += sample_count + + samples_count += sample_count + i += 1 + end + + results[:samples] = samples_count + # Set missed_samples and gc_samples to 0 as their values + # don't matter to us in this context. + results[:missed_samples] = 0 + results[:gc_samples] = 0 + results + end + + # Marshal dumps exit locations to the given filename. + # + # Usage: + # + # If `--yjit-exit-locations` is passed, a file named + # "yjit_exit_locations.dump" will automatically be generated. + # + # If you want to collect traces manually, call `dump_exit_locations` + # directly. + # + # Note that calling this in a script will generate stats after the + # dump is created, so the stats data may include exits from the + # dump itself. + # + # In a script call: + # + # at_exit do + # RubyVM::YJIT.dump_exit_locations("my_file.dump") + # end + # + # Then run the file with the following options: + # + # ruby --yjit --yjit-trace-exits test.rb + # + # Once the code is done running, use Stackprof to read the dump file. + # See Stackprof documentation for options. + def self.dump_exit_locations(filename) + unless trace_exit_locations_enabled? + raise ArgumentError, "--yjit-trace-exits must be enabled to use dump_exit_locations." + end + + File.binwrite(filename, Marshal.dump(RubyVM::YJIT.exit_locations)) + 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(context: false) + stats = Primitive.rb_yjit_get_stats(context) + return stats if stats.nil? + + stats[:object_shape_count] = Primitive.object_shape_count + return stats unless Primitive.rb_yjit_stats_enabled_p + + side_exits = total_exit_count(stats) + total_exits = side_exits + stats[:leave_interp_return] + + # Number of instructions that finish executing in YJIT. + # See :count-placement: about the subtraction. + retired_in_yjit = stats[:yjit_insns_count] - side_exits + + # Average length of instruction sequences executed by YJIT + avg_len_in_yjit = total_exits > 0 ? retired_in_yjit.to_f / total_exits : 0 + + # Proportion of instructions that retire in YJIT + total_insns_count = retired_in_yjit + stats[:vm_insns_count] + yjit_ratio_pct = 100.0 * retired_in_yjit.to_f / total_insns_count + stats[:total_insns_count] = total_insns_count + stats[:ratio_in_yjit] = yjit_ratio_pct + + # Make those stats available in RubyVM::YJIT.runtime_stats as well + stats[:side_exit_count] = side_exits + stats[:total_exit_count] = total_exits + stats[:avg_len_in_yjit] = avg_len_in_yjit + + stats + end + + # Format and print out counters as a String. This returns a non-empty + # content only when `--yjit-stats` is enabled. + def self.stats_string + # Lazily require StringIO to avoid breaking miniruby + require 'stringio' + strio = StringIO.new + _print_stats(out: strio) + strio.string + end + + # Produce disassembly for an iseq. This requires a `--enable-yjit=dev` build. + def self.disasm(iseq) # :nodoc: + # If a method or proc is passed in, get its iseq + iseq = RubyVM::InstructionSequence.of(iseq) + + if self.enabled? + # Produce the disassembly string + # Include the YARV iseq disasm in the string for additional context + iseq.disasm + "\n" + Primitive.rb_yjit_disasm_iseq(iseq) + else + iseq.disasm + end + end + + # Produce a list of instructions compiled by YJIT for an iseq + def self.insns_compiled(iseq) # :nodoc: + return nil unless self.enabled? + + # If a method or proc is passed in, get its iseq + iseq = RubyVM::InstructionSequence.of(iseq) + Primitive.rb_yjit_insns_compiled(iseq) + end + + # Discard existing compiled code to reclaim memory + # and allow for recompilations in the future. + def self.code_gc + Primitive.rb_yjit_code_gc + end + + def self.simulate_oom! # :nodoc: + Primitive.rb_yjit_simulate_oom_bang + end + + # Avoid calling a Ruby method here to not interfere with compilation tests + if Primitive.rb_yjit_stats_enabled_p + at_exit { print_and_dump_stats } + end + + class << self + # :stopdoc: + private + + # Print stats and dump exit locations + def print_and_dump_stats # :nodoc: + if Primitive.rb_yjit_print_stats_p + _print_stats + end + _dump_locations + end + + def _dump_locations # :nodoc: + return unless trace_exit_locations_enabled? + + filename = "yjit_exit_locations.dump" + dump_exit_locations(filename) + + $stderr.puts("YJIT exit locations dumped to `#{filename}`.") + end + + # Print a summary of reasons for adverse performance events (e.g. exits) + def _print_stats_reasons(stats, out) # :nodoc: + print_counters(stats, out: out, prefix: 'send_', prompt: 'method call fallback reasons: ') + print_counters(stats, out: out, prefix: 'invokeblock_', prompt: 'invokeblock fallback reasons: ') + print_counters(stats, out: out, prefix: 'invokesuper_', prompt: 'invokesuper fallback reasons: ') + print_counters(stats, out: out, prefix: 'guard_send_', prompt: 'method call exit reasons: ') + print_counters(stats, out: out, prefix: 'guard_invokeblock_', prompt: 'invokeblock exit reasons: ') + print_counters(stats, out: out, prefix: 'guard_invokesuper_', prompt: 'invokesuper exit reasons: ') + print_counters(stats, out: out, prefix: 'gbpp_', prompt: 'getblockparamproxy exit reasons: ') + print_counters(stats, out: out, prefix: 'getivar_', prompt: 'getinstancevariable exit reasons:') + print_counters(stats, out: out, prefix: 'setivar_', prompt: 'setinstancevariable exit reasons:') + %w[ + branchif + branchnil + branchunless + definedivar + expandarray + invokebuiltin + jump + leave + objtostring + opt_aref + opt_aref_with + opt_aset + opt_case_dispatch + opt_div + opt_getconstant_path + opt_minus + opt_mod + opt_mult + opt_plus + opt_succ + setlocal + splatkw + ].each do |insn| + print_counters(stats, out: out, prefix: "#{insn}_", prompt: "#{insn} exit reasons:", optional: true) + end + print_counters(stats, out: out, prefix: 'lshift_', prompt: 'left shift (opt_ltlt) exit reasons: ') + print_counters(stats, out: out, prefix: 'rshift_', prompt: 'right shift (>>) exit reasons: ') + print_counters(stats, out: out, prefix: 'invalidate_', prompt: 'invalidation reasons: ') + end + + # Format and print out counters + def _print_stats(out: $stderr) # :nodoc: + stats = runtime_stats(context: true) + return unless Primitive.rb_yjit_stats_enabled_p + + out.puts("***YJIT: Printing YJIT statistics on exit***") + + _print_stats_reasons(stats, out) + + # Number of failed compiler invocations + compilation_failure = stats[:compilation_failure] + + code_region_overhead = stats[:code_region_size] - (stats[:inline_code_size] + stats[:outlined_code_size]) + + out.puts "num_send: " + format_number(13, stats[:num_send]) + out.puts "num_send_known_class: " + format_number_pct(13, stats[:num_send_known_class], stats[:num_send]) + out.puts "num_send_polymorphic: " + format_number_pct(13, stats[:num_send_polymorphic], stats[:num_send]) + out.puts "num_send_megamorphic: " + format_number_pct(13, stats[:send_megamorphic], stats[:num_send]) + out.puts "num_send_dynamic: " + format_number_pct(13, stats[:num_send_dynamic], stats[:num_send]) + out.puts "num_send_cfunc: " + format_number_pct(13, stats[:num_send_cfunc], stats[:num_send]) + out.puts "num_send_cfunc_inline: " + format_number_pct(13, stats[:num_send_cfunc_inline], stats[:num_send_cfunc]) + out.puts "num_send_iseq: " + format_number_pct(13, stats[:num_send_iseq], stats[:num_send]) + out.puts "num_send_iseq_leaf: " + format_number_pct(13, stats[:num_send_iseq_leaf], stats[:num_send_iseq]) + out.puts "num_send_iseq_inline: " + format_number_pct(13, stats[:num_send_iseq_inline], stats[:num_send_iseq]) + if stats[:num_send_x86_rel32] != 0 || stats[:num_send_x86_reg] != 0 + out.puts "num_send_x86_rel32: " + format_number(13, stats[:num_send_x86_rel32]) + out.puts "num_send_x86_reg: " + format_number(13, stats[:num_send_x86_reg]) + end + out.puts "num_getivar_megamorphic: " + format_number(11, stats[:num_getivar_megamorphic]) + out.puts "num_setivar_megamorphic: " + format_number(11, stats[:num_setivar_megamorphic]) + out.puts "num_opt_case_megamorphic: " + format_number(10, stats[:num_opt_case_dispatch_megamorphic]) + out.puts "num_throw: " + format_number(13, stats[:num_throw]) + out.puts "num_throw_break: " + format_number_pct(13, stats[:num_throw_break], stats[:num_throw]) + out.puts "num_throw_retry: " + format_number_pct(13, stats[:num_throw_retry], stats[:num_throw]) + out.puts "num_throw_return: " + format_number_pct(13, stats[:num_throw_return], stats[:num_throw]) + out.puts "num_lazy_frame_check: " + format_number(13, stats[:num_lazy_frame_check]) + out.puts "num_lazy_frame_push: " + format_number_pct(13, stats[:num_lazy_frame_push], stats[:num_lazy_frame_check]) + out.puts "lazy_frame_count: " + format_number(13, stats[:lazy_frame_count]) + out.puts "lazy_frame_failure: " + format_number(13, stats[:lazy_frame_failure]) + + out.puts "iseq_stack_too_large: " + format_number(13, stats[:iseq_stack_too_large]) + out.puts "iseq_too_long: " + format_number(13, stats[:iseq_too_long]) + out.puts "temp_reg_opnd: " + format_number(13, stats[:temp_reg_opnd]) + out.puts "temp_mem_opnd: " + format_number(13, stats[:temp_mem_opnd]) + out.puts "temp_spill: " + format_number(13, stats[:temp_spill]) + out.puts "bindings_allocations: " + format_number(13, stats[:binding_allocations]) + out.puts "bindings_set: " + format_number(13, stats[:binding_set]) + out.puts "compilation_failure: " + format_number(13, compilation_failure) if compilation_failure != 0 + out.puts "live_iseq_count: " + format_number(13, stats[:live_iseq_count]) + out.puts "iseq_alloc_count: " + format_number(13, stats[:iseq_alloc_count]) + out.puts "compiled_iseq_entry: " + format_number(13, stats[:compiled_iseq_entry]) + out.puts "cold_iseq_entry: " + format_number_pct(13, stats[:cold_iseq_entry], stats[:compiled_iseq_entry] + stats[:cold_iseq_entry]) + out.puts "compiled_iseq_count: " + format_number(13, stats[:compiled_iseq_count]) + out.puts "compiled_blockid_count:" + format_number(13, stats[:compiled_blockid_count]) + out.puts "compiled_block_count: " + format_number(13, stats[:compiled_block_count]) + if stats[:compiled_blockid_count] != 0 + out.puts "versions_per_block: " + format_number(13, "%4.3f" % (stats[:compiled_block_count].fdiv(stats[:compiled_blockid_count]))) + end + out.puts "max_inline_versions: " + format_number(13, stats[:max_inline_versions]) + out.puts "compiled_branch_count: " + format_number(13, stats[:compiled_branch_count]) + out.puts "compile_time_ms: " + format_number(13, stats[:compile_time_ns] / (1000 * 1000)) + out.puts "block_next_count: " + format_number(13, stats[:block_next_count]) + out.puts "defer_count: " + format_number(13, stats[:defer_count]) + out.puts "defer_empty_count: " + format_number(13, stats[:defer_empty_count]) + + out.puts "branch_insn_count: " + format_number(13, stats[:branch_insn_count]) + out.puts "branch_known_count: " + format_number_pct(13, stats[:branch_known_count], stats[:branch_insn_count]) + + out.puts "freed_iseq_count: " + format_number(13, stats[:freed_iseq_count]) + out.puts "invalidation_count: " + format_number(13, stats[:invalidation_count]) + out.puts "inline_code_size: " + format_number(13, stats[:inline_code_size]) + out.puts "outlined_code_size: " + format_number(13, stats[:outlined_code_size]) + out.puts "code_region_size: " + format_number(13, stats[:code_region_size]) + out.puts "code_region_overhead: " + format_number_pct(13, code_region_overhead, stats[:code_region_size]) + + out.puts "freed_code_size: " + format_number(13, stats[:freed_code_size]) + out.puts "yjit_alloc_size: " + format_number(13, stats[:yjit_alloc_size]) if stats.key?(:yjit_alloc_size) + out.puts "live_context_size: " + format_number(13, stats[:live_context_size]) + out.puts "live_context_count: " + format_number(13, stats[:live_context_count]) + out.puts "live_page_count: " + format_number(13, stats[:live_page_count]) + out.puts "freed_page_count: " + format_number(13, stats[:freed_page_count]) + out.puts "code_gc_count: " + format_number(13, stats[:code_gc_count]) + out.puts "num_gc_obj_refs: " + format_number(13, stats[:num_gc_obj_refs]) + out.puts "object_shape_count: " + format_number(13, stats[:object_shape_count]) + out.puts "side_exit_count: " + format_number(13, stats[:side_exit_count]) + out.puts "total_exit_count: " + format_number(13, stats[:total_exit_count]) + out.puts "total_insns_count: " + format_number(13, stats[:total_insns_count]) + out.puts "vm_insns_count: " + format_number(13, stats[:vm_insns_count]) + out.puts "yjit_insns_count: " + format_number(13, stats[:yjit_insns_count]) + out.puts "ratio_in_yjit: " + ("%12.1f" % stats[:ratio_in_yjit]) + "%" + out.puts "avg_len_in_yjit: " + ("%13.1f" % stats[:avg_len_in_yjit]) + + print_sorted_exit_counts(stats, out: out, prefix: "exit_") + + print_sorted_method_calls(stats[:cfunc_calls], stats[:num_send_cfunc], out: out, type: 'C') + print_sorted_method_calls(stats[:iseq_calls], stats[:num_send_iseq], out: out, type: 'ISEQ') + end + + def print_sorted_method_calls(calls, num_calls, out:, type:, how_many: 20, left_pad: 4) # :nodoc: + return if calls.empty? + + # Sort calls by decreasing frequency and keep the top N + pairs = calls.map { |k,v| [k, v] } + pairs.sort_by! {|pair| -pair[1] } + pairs = pairs[0...how_many] + + top_n_total = pairs.sum { |name, count| count } + top_n_pct = 100.0 * top_n_total / num_calls + + out.puts "Top-#{pairs.size} most frequent #{type} calls (#{"%.1f" % top_n_pct}% of #{type} calls):" + + count_width = format_number(0, pairs[0][1]).length + pairs.each do |name, count| + padded_count = format_number_pct(count_width, count, num_calls) + out.puts(" #{padded_count}: #{name}") + end + end + + def print_sorted_exit_counts(stats, out:, prefix:, how_many: 20, left_pad: 4) # :nodoc: + total_exits = total_exit_count(stats) + + if total_exits > 0 + exits = [] + stats.each do |k, v| + if k.start_with?(prefix) + exits.push [k.to_s.delete_prefix(prefix), v] + end + end + + exits = exits.select { |_name, count| count > 0 }.max_by(how_many) { |_name, count| count } + + top_n_total = exits.sum { |name, count| count } + top_n_exit_pct = 100.0 * top_n_total / total_exits + + out.puts "Top-#{exits.size} most frequent exit ops (#{"%.1f" % top_n_exit_pct}% of exits):" + + count_width = format_number(0, exits[0][1]).length + exits.each do |name, count| + padded_count = format_number_pct(count_width, count, total_exits) + out.puts(" #{padded_count}: #{name}") + end + else + out.puts "total_exits: " + format_number(10, total_exits) + end + end + + def total_exit_count(stats, prefix: "exit_") # :nodoc: + total = 0 + stats.each do |k,v| + total += v if k.start_with?(prefix) + end + total + end + + def print_counters(counters, out:, prefix:, prompt:, optional: false) # :nodoc: + 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? + unless optional + out.puts(prompt) + out.puts(" (all relevant counters are zero)") + end + return + else + out.puts(prompt) + 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)| + padded_name = name.rjust(longest_name_length, ' ') + padded_count = format_number_pct(10, value, total) + out.puts(" #{padded_name}: #{padded_count}") + end + end + + # Format large numbers with comma separators for readability + def format_number(pad, number) # :nodoc: + s = number.to_s + i = s.index('.') || s.size + s.insert(i -= 3, ',') while i > 3 + s.rjust(pad, ' ') + end + + # Format a number along with a percentage over a total value + def format_number_pct(pad, number, total) # :nodoc: + padded_count = format_number(pad, number) + percentage = number.fdiv(total) * 100 + formatted_pct = "%4.1f%%" % percentage + "#{padded_count} (#{formatted_pct})" + end + + # :startdoc: + end +end |