6 files changed, 24 insertions, 9 deletions
diff --git a/lib/ruby_vm/rjit/insn_compiler.rb b/lib/ruby_vm/rjit/insn_compiler.rb
index aa37388a5b..bbfc8c3d0a 100644
--- a/lib/ruby_vm/rjit/insn_compiler.rb
+++ b/lib/ruby_vm/rjit/insn_compiler.rb
@@ -2769,6 +2769,22 @@ module RubyVM::RJIT
     # @param jit [RubyVM::RJIT::JITState]
     # @param ctx [RubyVM::RJIT::Context]
     # @param asm [RubyVM::RJIT::Assembler]
+    def jit_rb_str_bytesize(jit, ctx, asm, argc, known_recv_class)
+      asm.comment('String#bytesize')
+
+      recv = ctx.stack_pop(1)
+      asm.mov(C_ARGS[0], recv)
+      asm.call(C.rb_str_bytesize)
+
+      out_opnd = ctx.stack_push
+      asm.mov(out_opnd, C_RET)
+
+      true
+    end
+
+    # @param jit [RubyVM::RJIT::JITState]
+    # @param ctx [RubyVM::RJIT::Context]
+    # @param asm [RubyVM::RJIT::Assembler]
     def jit_rb_str_getbyte(jit, ctx, asm, argc, _known_recv_class)
       return false if argc != 1
       asm.comment('rb_str_getbyte')
@@ -2852,7 +2868,7 @@ module RubyVM::RJIT
       register_cfunc_method(String, :empty?, :jit_rb_str_empty_p)
       register_cfunc_method(String, :to_s, :jit_rb_str_to_s)
       register_cfunc_method(String, :to_str, :jit_rb_str_to_s)
-      #register_cfunc_method(String, :bytesize, :jit_rb_str_bytesize)
+      register_cfunc_method(String, :bytesize, :jit_rb_str_bytesize)
       #register_cfunc_method(String, :<<, :jit_rb_str_concat)
       #register_cfunc_method(String, :+@, :jit_rb_str_uplus)
 
diff --git a/rjit_c.c b/rjit_c.c
index 1a2aa0b1b1..dd6067f334 100644
--- a/rjit_c.c
+++ b/rjit_c.c
@@ -497,6 +497,7 @@ extern void rb_vm_setinstancevariable(const rb_iseq_t *iseq, VALUE obj, ID id, V
 extern VALUE rb_vm_throw(const rb_execution_context_t *ec, rb_control_frame_t *reg_cfp, rb_num_t throw_state, VALUE throwobj);
 extern VALUE rb_reg_new_ary(VALUE ary, int opt);
 extern void rb_vm_setclassvariable(const rb_iseq_t *iseq, const rb_control_frame_t *cfp, ID id, VALUE val, ICVARC ic);
+extern VALUE rb_str_bytesize(VALUE str);
 
 #include "rjit_c.rbinc"
 
diff --git a/rjit_c.rb b/rjit_c.rb
index 6d855d3ad8..ea68fcf4fb 100644
--- a/rjit_c.rb
+++ b/rjit_c.rb
@@ -607,6 +607,10 @@ module RubyVM::RJIT # :nodoc: all
     Primitive.cexpr! %q{ SIZET2NUM((size_t)rb_reg_nth_match) }
   end
 
+  def C.rb_str_bytesize
+    Primitive.cexpr! %q{ SIZET2NUM((size_t)rb_str_bytesize) }
+  end
+
   def C.rb_str_concat_literals
     Primitive.cexpr! %q{ SIZET2NUM((size_t)rb_str_concat_literals) }
   end
diff --git a/string.c b/string.c
index d661cfa003..a9359a7e3e 100644
--- a/string.c
+++ b/string.c
@@ -2186,7 +2186,7 @@ rb_str_length(VALUE str)
  *
  */
 
-static VALUE
+VALUE
 rb_str_bytesize(VALUE str)
 {
     return LONG2NUM(RSTRING_LEN(str));
diff --git a/tool/rjit/bindgen.rb b/tool/rjit/bindgen.rb
index 3c25edad09..b68123b38a 100755
--- a/tool/rjit/bindgen.rb
+++ b/tool/rjit/bindgen.rb
@@ -545,6 +545,7 @@ generator = BindingGenerator.new(
     rb_ary_clear
     rb_str_intern
     rb_vm_setclassvariable
+    rb_str_bytesize
   ],
   types: %w[
     CALL_DATA
diff --git a/yjit.c b/yjit.c
index 85401318ad..d0d8ae463a 100644
--- a/yjit.c
+++ b/yjit.c
@@ -442,13 +442,6 @@ rb_iseq_opcode_at_pc(const rb_iseq_t *iseq, const VALUE *pc)
     return rb_vm_insn_addr2opcode((const void *)at_pc);
 }
 
-// used by jit_rb_str_bytesize in codegen.rs
-VALUE
-rb_str_bytesize(VALUE str)
-{
-    return LONG2NUM(RSTRING_LEN(str));
-}
-
 unsigned long
 rb_RSTRING_LEN(VALUE str)
 {