ruby-changes:72112
From: Eileen <ko1@a...>
Date: Fri, 10 Jun 2022 02:00:08 +0900 (JST)
Subject: [ruby-changes:72112] 473ee328c5 (master): Add ability to trace exit locations in yjit (#5970)
https://git.ruby-lang.org/ruby.git/commit/?id=473ee328c5 From 473ee328c5be01ac6bb29659afcbe3361664bf68 Mon Sep 17 00:00:00 2001 From: "Eileen M. Uchitelle" <eileencodes@u...> Date: Thu, 9 Jun 2022 12:59:39 -0400 Subject: Add ability to trace exit locations in yjit (#5970) When running with `--yjit-stats` turned on, yjit can inform the user what the most common exits are. While this is useful information it doesn't tell you the source location of the code that exited or what the code that exited looks like. This change intends to fix that. To use the feature, run yjit with the `--yjit-trace-exits` option, which will record the backtrace for every exit that occurs. This functionality requires the stats feature to be turned on. Calling `--yjit-trace-exits` will automatically set the `--yjit-stats` option. Users must call `RubyVM::YJIT.dump_exit_locations(filename)` which will Marshal dump the contents of `RubyVM::YJIT.exit_locations` into a file based on the passed filename. *Example usage:* Given the following script, we write to a file called `concat_array.dump` the results of `RubyVM::YJIT.exit_locations`. ```ruby def concat_array ["t", "r", *x = "u", "e"].join end 1000.times do concat_array end RubyVM::YJIT.dump_exit_locations("concat_array.dump") ``` When we run the file with this branch and the appropriate flags the stacktrace will be recorded. Note Stackprof needs to be installed or you need to point to the library directly. ``` ./ruby --yjit --yjit-call-threshold=1 --yjit-trace-exits -I/Users/eileencodes/open_source/stackprof/lib test.rb ``` We can then read the dump file with Stackprof: ``` ./ruby -I/Users/eileencodes/open_source/stackprof/lib/ /Users/eileencodes/open_source/stackprof/bin/stackprof --text concat_array.dump ``` Results will look similar to the following: ``` ================================== Mode: () Samples: 1817 (0.00% miss rate) GC: 0 (0.00%) ================================== TOTAL (pct) SAMPLES (pct) FRAME 1001 (55.1%) 1001 (55.1%) concatarray 335 (18.4%) 335 (18.4%) invokeblock 178 (9.8%) 178 (9.8%) send 140 (7.7%) 140 (7.7%) opt_getinlinecache ...etc... ``` Simply inspecting the `concatarray` method will give `SOURCE UNAVAILABLE` because the source is insns.def. ``` ./ruby -I/Users/eileencodes/open_source/stackprof/lib/ /Users/eileencodes/open_source/stackprof/bin/stackprof --text concat_array.dump --method concatarray ``` Result: ``` concatarray (nonexistent.def:1) samples: 1001 self (55.1%) / 1001 total (55.1%) callers: 1000 ( 99.9%) Object#concat_array 1 ( 0.1%) Gem.suffixes callees (0 total): code: SOURCE UNAVAILABLE ``` However if we go deeper to the callee we can see the exact source of the `concatarray` exit. ``` ./ruby -I/Users/eileencodes/open_source/stackprof/lib/ /Users/eileencodes/open_source/stackprof/bin/stackprof --text concat_array.dump --method Object#concat_array ``` ``` Object#concat_array (/Users/eileencodes/open_source/rust_ruby/test.rb:1) samples: 0 self (0.0%) / 1000 total (55.0%) callers: 1000 ( 100.0%) block in <main> callees (1000 total): 1000 ( 100.0%) concatarray code: | 1 | def concat_array 1000 (55.0%) | 2 | ["t", "r", *x = "u", "e"].join | 3 | end ``` The `--walk` option is recommended for this feature as it make it easier to traverse the tree of exits. *Goals of this feature:* This feature is meant to give more information when working on YJIT. The idea is that if we know what code is exiting we can decide what areas to prioritize when fixing exits. In some cases this means adding prioritizing avoiding certain exits in yjit. In more complex cases it might mean changing the Ruby code to be more performant when run with yjit. Ultimately the more information we have about what code is exiting AND why, the better we can make yjit. *Known limitations:* * Due to tracing exits, running this on large codebases like Rails can be quite slow. * On complex methods it can still be difficult to pinpoint the exact cause of an exit. * Stackprof is a requirement to to view the backtrace information from the dump file. Co-authored-by: Aaron Patterson <tenderlove@r...> Co-authored-by: Aaron Patterson <tenderlove@r...> --- test/ruby/test_yjit_exit_locations.rb | 101 +++++++++++++++ yjit.c | 91 ++++++++++++++ yjit.rb | 100 +++++++++++++++ yjit/bindgen/src/main.rs | 4 + yjit/src/codegen.rs | 7 ++ yjit/src/cruby_bindings.inc.rs | 15 +++ yjit/src/invariants.rs | 5 + yjit/src/options.rs | 5 + yjit/src/stats.rs | 227 ++++++++++++++++++++++++++++++++++ yjit/src/yjit.rs | 2 + 10 files changed, 557 insertions(+) create mode 100644 test/ruby/test_yjit_exit_locations.rb diff --git a/test/ruby/test_yjit_exit_locations.rb b/test/ruby/test_yjit_exit_locations.rb new file mode 100644 index 0000000000..d708bed5e9 --- /dev/null +++ b/test/ruby/test_yjit_exit_locations.rb @@ -0,0 +1,101 @@ https://github.com/ruby/ruby/blob/trunk/test/ruby/test_yjit_exit_locations.rb#L1 +# frozen_string_literal: true +# +# This set of tests can be run with: +# make test-all TESTS='test/ruby/test_yjit_exit_locations.rb' RUN_OPTS="--yjit-call-threshold=1" + +require 'test/unit' +require 'envutil' +require 'tmpdir' +require_relative '../lib/jit_support' + +return unless defined?(RubyVM::YJIT) && RubyVM::YJIT.enabled? && RubyVM::YJIT.trace_exit_locations_enabled? + +# Tests for YJIT with assertions on tracing exits +# insipired by the MJIT tests in test/ruby/test_yjit.rb +class TestYJITExitLocations < Test::Unit::TestCase + def test_yjit_trace_exits_and_v_no_error + _stdout, stderr, _status = EnvUtil.invoke_ruby(%w(-v --yjit-trace-exits), '', true, true) + refute_includes(stderr, "NoMethodError") + end + + def test_trace_exits_setclassvariable + script = 'class Foo; def self.foo; @@foo = 1; end; end; Foo.foo' + assert_exit_locations(script) + end + + def test_trace_exits_putobject + assert_exit_locations('true') + assert_exit_locations('123') + assert_exit_locations(':foo') + end + + def test_trace_exits_opt_not + assert_exit_locations('!false') + assert_exit_locations('!nil') + assert_exit_locations('!true') + assert_exit_locations('![]') + end + + private + + def assert_exit_locations(test_script) + write_results = <<~RUBY + IO.open(3).write Marshal.dump(RubyVM::YJIT.exit_locations) + RUBY + + script = <<~RUBY + _test_proc = -> { + #{test_script} + } + result = _test_proc.call + #{write_results} + RUBY + + exit_locations = eval_with_jit(script) + + assert exit_locations.key?(:raw) + assert exit_locations.key?(:frames) + assert exit_locations.key?(:lines) + assert exit_locations.key?(:samples) + assert exit_locations.key?(:missed_samples) + assert exit_locations.key?(:gc_samples) + + assert_equal 0, exit_locations[:missed_samples] + assert_equal 0, exit_locations[:gc_samples] + + assert_not_empty exit_locations[:raw] + assert_not_empty exit_locations[:frames] + assert_not_empty exit_locations[:lines] + + exit_locations[:frames].each do |frame_id, frame| + assert frame.key?(:name) + assert frame.key?(:file) + assert frame.key?(:samples) + assert frame.key?(:total_samples) + assert frame.key?(:edges) + end + end + + def eval_with_jit(script) + args = [ + "--disable-gems", + "--yjit-call-threshold=1", + "--yjit-trace-exits" + ] + args << "-e" << script_shell_encode(script) + stats_r, stats_w = IO.pipe + out, err, status = EnvUtil.invoke_ruby(args, + '', true, true, timeout: 1000, ios: { 3 => stats_w } + ) + stats_w.close + stats = stats_r.read + stats = Marshal.load(stats) if !stats.empty? + stats_r.close + stats + end + + def script_shell_encode(s) + # We can't pass utf-8-encoded characters directly in a shell arg. But we can use Ruby \u constants. + s.chars.map { |c| c.ascii_only? ? c : "\\u%x" % c.codepoints[0] }.join + end +end diff --git a/yjit.c b/yjit.c index b97fcdb62c..b4e36e0b68 100644 --- a/yjit.c +++ b/yjit.c @@ -25,6 +25,7 @@ https://github.com/ruby/ruby/blob/trunk/yjit.c#L25 #include "probes.h" #include "probes_helper.h" #include "iseq.h" +#include "ruby/debug.h" // For mmapp(), sysconf() #ifndef _WIN32 @@ -83,6 +84,94 @@ rb_yjit_mark_executable(void *mem_block, uint32_t mem_size) https://github.com/ruby/ruby/blob/trunk/yjit.c#L84 } } +# define PTR2NUM(x) (rb_int2inum((intptr_t)(void *)(x))) + +// For a given raw_sample (frame), set the hash with the caller's +// name, file, and line number. Return the hash with collected frame_info. +static void +rb_yjit_add_frame(VALUE hash, VALUE frame) +{ + VALUE frame_id = PTR2NUM(frame); + + if (RTEST(rb_hash_aref(hash, frame_id))) { + return; + } else { + VALUE frame_info = rb_hash_new(); + // Full label for the frame + VALUE name = rb_profile_frame_full_label(frame); + // Absolute path of the frame from rb_iseq_realpath + VALUE file = rb_profile_frame_absolute_path(frame); + // Line number of the frame + VALUE line = rb_profile_frame_first_lineno(frame); + + // If absolute path isn't available use the rb_iseq_path + if (NIL_P(file)) { + file = rb_profile_frame_path(frame); + } + + rb_hash_aset(frame_info, ID2SYM(rb_intern("name")), name); + rb_hash_aset(frame_info, ID2SYM(rb_intern("file")), file); + + if (line != INT2FIX(0)) { + (... truncated) -- ML: ruby-changes@q... Info: http://www.atdot.net/~ko1/quickml/