ruby/yjit.rb

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13 KiB
Ruby

# frozen_string_literal: true
# This module allows for introspection of YJIT, CRuby's experimental in-process
# just-in-time compiler. This module exists only to help develop YJIT, as such,
# everything in the module is highly implementation specific and comes with no
# API stability guarantee whatsoever.
#
# This module may not exist if YJIT does not support the particular platform
# for which CRuby is built. There is also no API stability guarantee as to in
# what situations this module is defined.
module RubyVM::YJIT
# Check if YJIT is enabled
def self.enabled?
Primitive.cexpr! 'RBOOL(rb_yjit_enabled_p())'
end
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?
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
# 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
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] + 1
i += 1 # consume the 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] += 1
end
frame_info = frames[frame_id]
frame_info[:total_samples] += 1
frame_info[:lines][line_samples[idx]] ||= [0, 0]
frame_info[:lines][line_samples[idx]][0] += 1
prev_frame_id = frame_id
end
i += stack_length # consume the stack
top_frame_id = prev_frame_id
top_frame_line = 1
sample_count = raw_samples[i]
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
stats = Primitive.rb_yjit_get_stats
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[:exec_instruction] - side_exits
# Average length of instruction sequences executed by YJIT
avg_len_in_yjit = retired_in_yjit.to_f / total_exits
# This only available on yjit stats builds
if stats.key?(:vm_insns_count)
# 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
end
# 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
# Produce disassembly for an iseq
def self.disasm(iseq)
# 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)
# If a method or proc is passed in, get its iseq
iseq = RubyVM::InstructionSequence.of(iseq)
if self.enabled?
Primitive.rb_yjit_insns_compiled(iseq)
else
Qnil
end
end
# Free and recompile all existing JIT code
def self.code_gc
Primitive.rb_yjit_code_gc
end
def self.simulate_oom!
Primitive.rb_yjit_simulate_oom_bang
end
# Avoid calling a method here to not interfere with compilation tests
if Primitive.rb_yjit_stats_enabled_p
at_exit do
_print_stats
_dump_locations
end
end
class << self
private
def _dump_locations
return unless trace_exit_locations_enabled?
filename = "yjit_exit_locations.dump"
dump_exit_locations(filename)
$stderr.puts("YJIT exit locations dumped to `#{filename}`.")
end
# Format and print out counters
def _print_stats
stats = runtime_stats
return unless stats
$stderr.puts("***YJIT: Printing YJIT statistics on exit***")
print_counters(stats, prefix: 'send_', prompt: 'method call exit reasons: ')
print_counters(stats, prefix: 'invokeblock_', prompt: 'invokeblock exit reasons: ')
print_counters(stats, prefix: 'invokesuper_', prompt: 'invokesuper exit reasons: ')
print_counters(stats, prefix: 'leave_', prompt: 'leave exit reasons: ')
print_counters(stats, prefix: 'gbpp_', prompt: 'getblockparamproxy exit reasons: ')
print_counters(stats, prefix: 'getivar_', prompt: 'getinstancevariable exit reasons:')
print_counters(stats, prefix: 'setivar_', prompt: 'setinstancevariable exit reasons:')
print_counters(stats, prefix: 'oaref_', prompt: 'opt_aref exit reasons: ')
print_counters(stats, prefix: 'expandarray_', prompt: 'expandarray exit reasons: ')
print_counters(stats, prefix: 'opt_getinlinecache_', prompt: 'opt_getinlinecache exit reasons: ')
print_counters(stats, prefix: 'invalidate_', prompt: 'invalidation reasons: ')
# Number of failed compiler invocations
compilation_failure = stats[:compilation_failure]
$stderr.puts "bindings_allocations: " + ("%10d" % stats[:binding_allocations])
$stderr.puts "bindings_set: " + ("%10d" % stats[:binding_set])
$stderr.puts "compilation_failure: " + ("%10d" % compilation_failure) if compilation_failure != 0
$stderr.puts "compiled_iseq_count: " + ("%10d" % stats[:compiled_iseq_count])
$stderr.puts "compiled_block_count: " + ("%10d" % stats[:compiled_block_count])
$stderr.puts "compiled_branch_count: " + ("%10d" % stats[:compiled_branch_count])
$stderr.puts "block_next_count: " + ("%10d" % stats[:block_next_count])
$stderr.puts "defer_count: " + ("%10d" % stats[:defer_count])
$stderr.puts "freed_iseq_count: " + ("%10d" % stats[:freed_iseq_count])
$stderr.puts "invalidation_count: " + ("%10d" % stats[:invalidation_count])
$stderr.puts "constant_state_bumps: " + ("%10d" % stats[:constant_state_bumps])
$stderr.puts "inline_code_size: " + ("%10d" % stats[:inline_code_size])
$stderr.puts "outlined_code_size: " + ("%10d" % stats[:outlined_code_size])
$stderr.puts "freed_code_size: " + ("%10d" % stats[:freed_code_size])
$stderr.puts "code_region_size: " + ("%10d" % stats[:code_region_size])
$stderr.puts "yjit_alloc_size: " + ("%10d" % stats[:yjit_alloc_size]) if stats.key?(:yjit_alloc_size)
$stderr.puts "live_page_count: " + ("%10d" % stats[:live_page_count])
$stderr.puts "freed_page_count: " + ("%10d" % stats[:freed_page_count])
$stderr.puts "code_gc_count: " + ("%10d" % stats[:code_gc_count])
$stderr.puts "num_gc_obj_refs: " + ("%10d" % stats[:num_gc_obj_refs])
$stderr.puts "object_shape_count: " + ("%10d" % stats[:object_shape_count])
$stderr.puts "side_exit_count: " + ("%10d" % stats[:side_exit_count])
$stderr.puts "total_exit_count: " + ("%10d" % stats[:total_exit_count])
$stderr.puts "total_insns_count: " + ("%10d" % stats[:total_insns_count]) if stats.key?(:total_insns_count)
if stats.key?(:vm_insns_count)
$stderr.puts "vm_insns_count: " + ("%10d" % stats[:vm_insns_count])
end
$stderr.puts "yjit_insns_count: " + ("%10d" % stats[:exec_instruction])
if stats.key?(:ratio_in_yjit)
$stderr.puts "ratio_in_yjit: " + ("%9.1f" % stats[:ratio_in_yjit]) + "%"
end
$stderr.puts "avg_len_in_yjit: " + ("%10.1f" % stats[:avg_len_in_yjit])
print_sorted_exit_counts(stats, prefix: "exit_")
end
def print_sorted_exit_counts(stats, prefix:, how_many: 20, left_pad: 4)
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 }.sort_by { |_name, count| -count }.first(how_many)
total_exits = total_exit_count(stats)
if total_exits > 0
top_n_total = exits.map { |name, count| count }.sum
top_n_exit_pct = 100.0 * top_n_total / total_exits
$stderr.puts "Top-#{exits.size} most frequent exit ops (#{"%.1f" % top_n_exit_pct}% of exits):"
longest_insn_name_len = exits.map { |name, count| name.length }.max
exits.each do |name, count|
padding = longest_insn_name_len + left_pad
padded_name = "%#{padding}s" % name
padded_count = "%10d" % count
percent = 100.0 * count / total_exits
formatted_percent = "%.1f" % percent
$stderr.puts("#{padded_name}: #{padded_count} (#{formatted_percent}%)" )
end
else
$stderr.puts "total_exits: " + ("%10d" % total_exits)
end
end
def total_exit_count(stats, prefix: "exit_")
total = 0
stats.each do |k,v|
total += v if k.start_with?(prefix)
end
total
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