ZJIT: Optimize `ObjToString` with type guards (#14469)

* failing test for ObjToString optimization with GuardType

* profile ObjToString receiver and rewrite with guard

* adjust integration tests for objtostring type guard optimization

* Implement new GuardTypeNot HIR; objtostring sends to_s directly on profiled nonstrings

* codegen for GuardTypeNot

* typo fixes

* better name for tests; fix side exit reason for GuardTypeNot

* revert accidental change

* make bindgen

* Fix is_string to identify subclasses of String; fix codegen for identifying if val is String

1 files changed, 55 insertions, 0 deletions

diff --git a/test/ruby/test_zjit.rb b/test/ruby/test_zjit.rb
index 4d8eb30c80..b5bdd0d12b 100644
--- a/test/ruby/test_zjit.rb
+++ b/test/ruby/test_zjit.rb
@@ -2088,6 +2088,61 @@ class TestZJIT < Test::Unit::TestCase
     }
   end
 
+  def test_objtostring_profiled_string_fastpath
+    assert_compiles '"foo"', %q{
+      def test(str)
+        "#{str}"
+      end
+      test('foo'); test('foo') # profile as string
+    }, call_threshold: 2
+  end
+
+  def test_objtostring_profiled_string_subclass_fastpath
+    assert_compiles '"foo"', %q{
+      class MyString < String; end
+
+      def test(str)
+        "#{str}"
+      end
+
+      foo = MyString.new("foo")
+      test(foo); test(foo) # still profiles as string
+    }, call_threshold: 2
+  end
+
+  def test_objtostring_profiled_string_fastpath_exits_on_nonstring
+    assert_compiles '"1"', %q{
+      def test(str)
+        "#{str}"
+      end
+
+      test('foo') # profile as string
+      test(1)
+    }, call_threshold: 2
+  end
+
+  def test_objtostring_profiled_nonstring_calls_to_s
+    assert_compiles '"[1, 2, 3]"', %q{
+      def test(str)
+        "#{str}"
+      end
+
+      test([1,2,3]); # profile as nonstring
+      test([1,2,3]);
+    }, call_threshold: 2
+  end
+
+  def test_objtostring_profiled_nonstring_guard_exits_when_string
+    assert_compiles '"foo"', %q{
+      def test(str)
+        "#{str}"
+      end
+
+      test([1,2,3]); # profiles as nonstring
+      test('foo');
+    }, call_threshold: 2
+  end
+
   def test_string_bytesize_with_guard
     assert_compiles '5', %q{
       def test(str)