YJIT: No need to reject splat+zsuper

There is nothing special about argument handling when it comes to zsuper
if you look around in the VM. Everything passes removing these fallback
reasons. It was ~16% on `railsbench`.

bootstraptest/test_yjit.rb

@@ -2444,6 +2444,18 @@ assert_equal '[0, 2]', %q{
   B.new.foo
 }
 
+# invokesuper zsuper in a bmethod
+assert_equal 'ok', %q{
+  class Foo
+    define_method(:itself) { super }
+  end
+  begin
+    Foo.new.itself
+  rescue RuntimeError
+    :ok
+  end
+}
+
 # Call to fixnum
 assert_equal '[true, false]', %q{
   def is_odd(obj)

yjit/src/codegen.rs

@@ -5887,15 +5887,6 @@ fn gen_send_cfunc(
         return None;
     }
 
-    if flags & VM_CALL_ARGS_SPLAT != 0 && flags & VM_CALL_ZSUPER != 0 {
-        // zsuper methods are super calls without any arguments.
-        // They are also marked as splat, but don't actually have an array
-        // they pull arguments from, instead we need to change to call
-        // a different method with the current stack.
-        gen_counter_incr(asm, Counter::send_args_splat_cfunc_zuper);
-        return None;
-    }
-
     let kw_arg = unsafe { vm_ci_kwarg(ci) };
     let kw_arg_num = if kw_arg.is_null() {
         0
@@ -6425,7 +6416,6 @@ fn gen_send_iseq(
     exit_if_has_rest_and_supplying_kws(asm, iseq_has_rest, iseq, supplying_kws)?;
     exit_if_supplying_kw_and_has_no_kw(asm, supplying_kws, iseq)?;
     exit_if_supplying_kws_and_accept_no_kwargs(asm, supplying_kws, iseq)?;
-    exit_if_splat_and_zsuper(asm, flags)?;
     exit_if_doing_kw_and_splat(asm, doing_kw_call, flags)?;
     exit_if_wrong_number_arguments(asm, arg_setup_block, opts_filled, flags, opt_num, iseq_has_rest)?;
     exit_if_doing_kw_and_opts_missing(asm, doing_kw_call, opts_missing)?;
@@ -7327,15 +7317,6 @@ fn exit_if_supplying_kws_and_accept_no_kwargs(asm: &mut Assembler, supplying_kws
     )
 }
 
-#[must_use]
-fn exit_if_splat_and_zsuper(asm: &mut Assembler, flags: u32) -> Option<()> {
-    // zsuper methods are super calls without any arguments.
-    // They are also marked as splat, but don't actually have an array
-    // they pull arguments from, instead we need to change to call
-    // a different method with the current stack.
-    exit_if(asm, flags & VM_CALL_ARGS_SPLAT != 0 && flags & VM_CALL_ZSUPER != 0, Counter::send_iseq_zsuper)
-}
-
 #[must_use]
 fn exit_if_doing_kw_and_splat(asm: &mut Assembler, doing_kw_call: bool, flags: u32) -> Option<()> {
     exit_if(asm, doing_kw_call && flags & VM_CALL_ARGS_SPLAT != 0, Counter::send_iseq_splat_with_kw)

yjit/src/stats.rs

@@ -321,7 +321,6 @@ make_counters! {
     send_kw_splat,
     send_singleton_class,
     send_args_splat_super,
-    send_iseq_zsuper,
     send_block_arg,
     send_ivar_set_method,
     send_zsuper_method,
@@ -378,7 +377,6 @@ make_counters! {
     send_args_splat_aset,
     send_args_splat_opt_call,
     send_args_splat_cfunc_var_args,
-    send_args_splat_cfunc_zuper,
     send_iseq_splat_arity_error,
     send_splat_too_long,
     send_send_not_imm,