This module allows for introspection of YJIT, CRuby’s 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.
Public Class Methods
code_gc() click to toggle source
Free and recompile all existing JIT code
# File yjit.rb, line 209def self.code_gc Primitive.rb_yjit_code_gcend
disasm(iseq) click to toggle source
Produce disassembly for an iseq
# File yjit.rb, line 183def 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 endend
dump_exit_locations(filename) click to toggle source
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.
# File yjit.rb, line 138def 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
enabled?() click to toggle source
Check if YJIT is enabled
# File yjit.rb, line 13def self.enabled? Primitive.cexpr! 'RBOOL(rb_yjit_enabled_p())'end
exit_locations() click to toggle source
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.
# File yjit.rb, line 36def 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 resultsend
insns_compiled(iseq) click to toggle source
Produce a list of instructions compiled by YJIT for an iseq
# File yjit.rb, line 197def 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 endend
reset_stats!() click to toggle source
Discard statistics collected for –yjit-stats.
# File yjit.rb, line 28def self.reset_stats! Primitive.rb_yjit_reset_stats_bangend
runtime_stats() click to toggle source
Return a hash for statistics generated for the –yjit-stats command line option. Return nil when option is not passed or unavailable.
# File yjit.rb, line 148def 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 statsend
stats_enabled?() click to toggle source
Check if –yjit-stats is used.
# File yjit.rb, line 18def self.stats_enabled? Primitive.rb_yjit_stats_enabled_pend
trace_exit_locations_enabled?() click to toggle source
Check if rb_yjit_trace_exit_locations_enabled_p is enabled.
# File yjit.rb, line 23def self.trace_exit_locations_enabled? Primitive.rb_yjit_trace_exit_locations_enabled_pend
