TracePoint support

This change fixes some cases where YJIT fails to fire tracing events.
Most of the situations YJIT did not handle correctly involves enabling
tracing while running inside generated code.

A new operation to invalidate all generated code is added, which uses
patching to make generated code exit at the next VM instruction
boundary. A new routine called `jit_prepare_routine_call()` is
introduced to facilitate this and should be used when generating code
that could allocate, or could otherwise use `RB_VM_LOCK_ENTER()`.

The `c_return` event is fired in the middle of an instruction as opposed
to at an instruction boundary, so it requires special handling. C method
call return points are patched to go to a fucntion which does everything
the interpreter does, including firing the `c_return` event. The
generated code for C method calls normally does not fire the event.

Invalided code should not change after patching so the exits are not
clobbered. A new variable is introduced to track the region of code that
should not change.

1 files changed, 214 insertions, 0 deletions

diff --git a/bootstraptest/test_yjit.rb b/bootstraptest/test_yjit.rb
index 8b2d5b044e..00abed9f3b 100644
--- a/bootstraptest/test_yjit.rb
+++ b/bootstraptest/test_yjit.rb
@@ -1612,3 +1612,217 @@ end
 bar(123, 1.1)
 bar(123, 1.1)
 }
+
+# test enabling a line TracePoint in a C method call
+assert_equal '[[:line, true]]', %q{
+  events = []
+  events.instance_variable_set(
+    :@tp,
+    TracePoint.new(:line) { |tp| events << [tp.event, tp.lineno] if tp.path == __FILE__ }
+  )
+  def events.to_str
+    @tp.enable; ''
+  end
+
+  # Stay in generated code while enabling tracing
+  def events.compiled(obj)
+    String(obj)
+    @tp.disable; __LINE__
+  end
+
+  line = events.compiled(events)
+  events[0][-1] = (events[0][-1] == line)
+
+  events
+}
+
+# test enabling a c_return TracePoint in a C method call
+assert_equal '[[:c_return, :String, :string_alias, "events_to_str"]]', %q{
+  events = []
+  events.instance_variable_set(:@tp, TracePoint.new(:c_return) { |tp| events << [tp.event, tp.method_id, tp.callee_id, tp.return_value] })
+  def events.to_str
+    @tp.enable; 'events_to_str'
+  end
+
+  # Stay in generated code while enabling tracing
+  alias string_alias String
+  def events.compiled(obj)
+    string_alias(obj)
+    @tp.disable
+  end
+
+  events.compiled(events)
+
+  events
+}
+
+# test enabling a TracePoint that targets a particular line in a C method call
+assert_equal '[true]', %q{
+  events = []
+  events.instance_variable_set(:@tp, TracePoint.new(:line) { |tp| events << tp.lineno })
+  def events.to_str
+    @tp.enable(target: method(:compiled))
+    ''
+  end
+
+  # Stay in generated code while enabling tracing
+  def events.compiled(obj)
+    String(obj)
+    __LINE__
+  end
+
+  line = events.compiled(events)
+  events[0] = (events[0] == line)
+
+  events
+}
+
+# test enabling tracing in the middle of splatarray
+assert_equal '[true]', %q{
+  events = []
+  obj = Object.new
+  obj.instance_variable_set(:@tp, TracePoint.new(:line) { |tp| events << tp.lineno })
+  def obj.to_a
+    @tp.enable(target: method(:compiled))
+    []
+  end
+
+  # Enable tracing in the middle of the splatarray instruction
+  def obj.compiled(obj)
+    * = *obj
+    __LINE__
+  end
+
+  obj.compiled([])
+  line = obj.compiled(obj)
+  events[0] = (events[0] == line)
+
+  events
+}
+
+# test enabling tracing in the middle of opt_aref. Different since the codegen
+# for it ends in a jump.
+assert_equal '[true]', %q{
+  def lookup(hash, tp)
+    hash[42]
+    tp.disable; __LINE__
+  end
+
+  lines = []
+  tp = TracePoint.new(:line) { lines << _1.lineno if _1.path == __FILE__ }
+
+  lookup(:foo, tp)
+  lookup({}, tp)
+
+  enable_tracing_on_missing = Hash.new { tp.enable }
+
+  expected_line = lookup(enable_tracing_on_missing, tp)
+
+  lines[0] = true if lines[0] == expected_line
+
+  lines
+}
+
+# test enabling c_call tracing before compiling
+assert_equal '[[:c_call, :itself]]', %q{
+  def shouldnt_compile
+    itself
+  end
+
+  events = []
+  tp = TracePoint.new(:c_call) { |tp| events << [tp.event, tp.method_id] }
+
+  # assume first call compiles
+  tp.enable { shouldnt_compile }
+
+  events
+}
+
+# test enabling c_return tracing before compiling
+assert_equal '[[:c_return, :itself, main]]', %q{
+  def shouldnt_compile
+    itself
+  end
+
+  events = []
+  tp = TracePoint.new(:c_return) { |tp| events << [tp.event, tp.method_id, tp.return_value] }
+
+  # assume first call compiles
+  tp.enable { shouldnt_compile }
+
+  events
+}
+
+# test enabling tracing for a suspended fiber
+assert_equal '[[:return, 42]]', %q{
+  def traced_method
+    Fiber.yield
+    42
+  end
+
+  events = []
+  tp = TracePoint.new(:return) { events << [_1.event, _1.return_value] }
+  # assume first call compiles
+  fiber = Fiber.new { traced_method }
+  fiber.resume
+  tp.enable(target: method(:traced_method))
+  fiber.resume
+
+  events
+}
+
+# test compiling on non-tracing ractor then running on a tracing one
+assert_equal '[:itself]', %q{
+  def traced_method
+    itself
+  end
+
+
+  tracing_ractor = Ractor.new do
+    # 1: start tracing
+    events = []
+    tp = TracePoint.new(:c_call) { events << _1.method_id }
+    tp.enable
+    Ractor.yield(nil)
+
+    # 3: run comipled method on tracing ractor
+    Ractor.yield(nil)
+    traced_method
+
+    events
+  ensure
+    tp&.disable
+  end
+
+  tracing_ractor.take
+
+  # 2: compile on non tracing ractor
+  traced_method
+
+  tracing_ractor.take
+  tracing_ractor.take
+}
+
+# Try to hit a lazy branch stub while another ractor enables tracing
+assert_equal '42', %q{
+  def compiled(arg)
+    if arg
+      arg + 1
+    else
+      itself
+      itself
+    end
+  end
+
+  ractor = Ractor.new do
+    compiled(false)
+    Ractor.yield(nil)
+    compiled(41)
+  end
+
+  tp = TracePoint.new(:line) { itself }
+  ractor.take
+  tp.enable
+
+  ractor.take
+}