2 files changed, 35 insertions, 1 deletions
diff --git a/bootstraptest/test_yjit.rb b/bootstraptest/test_yjit.rb
index 34cb87ed88..ed8bd94e7c 100644
--- a/bootstraptest/test_yjit.rb
+++ b/bootstraptest/test_yjit.rb
@@ -1227,6 +1227,38 @@ assert_equal '42', %q{
   run
 }
 
+# splatting an empty array on a specialized method
+assert_equal 'ok', %q{
+  def run
+    "ok".to_s(*[])
+  end
+
+  run
+  run
+}
+
+# splatting an single element array on a specialized method
+assert_equal '[1]', %q{
+  def run
+    [].<<(*[1])
+  end
+
+  run
+  run
+}
+
+# specialized method with wrong args
+assert_equal 'ok', %q{
+  def run(x)
+    "bad".to_s(123) if x
+  rescue
+    :ok
+  end
+
+  run(false)
+  run(true)
+}
+
 # getinstancevariable on Symbol
 assert_equal '[nil, nil]', %q{
   # @foo to exercise the getinstancevariable instruction
diff --git a/yjit/src/codegen.rs b/yjit/src/codegen.rs
index 7c302707db..e853f1308a 100644
--- a/yjit/src/codegen.rs
+++ b/yjit/src/codegen.rs
@@ -4987,10 +4987,12 @@ fn gen_send_cfunc(
     }
 
     // Delegate to codegen for C methods if we have it.
-    if kw_arg.is_null() && flags & VM_CALL_OPT_SEND == 0 {
+    if kw_arg.is_null() && flags & VM_CALL_OPT_SEND == 0 && flags & VM_CALL_ARGS_SPLAT == 0 && (cfunc_argc == -1 || argc == cfunc_argc) {
         let codegen_p = lookup_cfunc_codegen(unsafe { (*cme).def });
+        let expected_stack_after = asm.ctx.get_stack_size() as i32 - argc;
         if let Some(known_cfunc_codegen) = codegen_p {
             if known_cfunc_codegen(jit, asm, ocb, ci, cme, block, argc, recv_known_klass) {
+                assert_eq!(expected_stack_after, asm.ctx.get_stack_size() as i32);
                 // cfunc codegen generated code. Terminate the block so
                 // there isn't multiple calls in the same block.
                 jump_to_next_insn(jit, asm, ocb);