Special-case jit_guard_known_class for strings. This can remove (#5920)

runtime guard-checks for String#to_s, making some blocks too
short to invalidate later. Add NOPs in those cases to reserve space.

1 files changed, 10 insertions, 0 deletions

diff --git a/bootstraptest/test_yjit.rb b/bootstraptest/test_yjit.rb
index b0c17229c5..6d0ba93fc8 100644
--- a/bootstraptest/test_yjit.rb
+++ b/bootstraptest/test_yjit.rb
@@ -1337,6 +1337,16 @@ assert_equal 'foo123', %q{
   make_str("foo", 123)
 }
 
+# test that invalidation of String#to_s doesn't crash
+assert_equal 'meh', %q{
+  class String
+    def to_s
+      "meh"
+    end
+  end
+  "".to_s
+}
+
 # test string interpolation with overridden to_s
 assert_equal 'foo', %q{
   class String