remove redundant arity checking calling JIT-generated code

JIT-generated code has arity checking built in, but the
interpreter-to-JIT path unnecessarily checked arity before
jumping to JITted code.

src/racket/src/eval.c

@@ -2763,12 +2763,6 @@ scheme_do_eval(Scheme_Object *obj, int num_rands, Scheme_Object **rands,
       
       DO_CHECK_FOR_BREAK(p, );
 
-      if (!scheme_native_arity_check(obj, num_rands)) {
-	scheme_wrong_count_m((const char *)obj, -1, -1,
-			     num_rands, rands, 0);
-	return NULL;
-      }
-
       data = ((Scheme_Native_Closure *)obj)->code;
 
       /* Enlarge the runstack? This max_let_depth is in bytes instead of words. */

src/racket/src/jit.c

@@ -3678,14 +3678,11 @@ static int generate_case_lambda_dispatch(mz_jit_state *jitter, Scheme_Case_Lambd
     if (has_rest && num_params)
       --num_params;
 
-    /* Check for arity match - not needed in getarg mode if this
-       is the last case, since the arity check as already done. */
-    if (!do_getarg || (i < cnt - 1)) {
+    /* Check for arity match. */
     if (!has_rest)
       ref = jit_bnei_i(jit_forward(), JIT_R1, num_params);
     else
       ref = jit_blti_i(jit_forward(), JIT_R1, num_params);
-    }
 
     /* Function-argument handling for this case: */
     if (do_getarg) {
@@ -3701,9 +3698,7 @@ static int generate_case_lambda_dispatch(mz_jit_state *jitter, Scheme_Case_Lambd
     jit_jmpr(JIT_V1);
     CHECK_LIMIT();
     
-    if (!do_getarg || (i < cnt - 1)) {
     mz_patch_branch(ref);
-    }
     /* Try the next one... */
   }
 

src/racket/src/jitcall.c

@@ -78,7 +78,8 @@ static jit_insn *generate_proc_struct_retry(mz_jit_state *jitter, int num_rands,
   CHECK_LIMIT();
 
   /* It's a native closure, but we can't just jump to it, in case
-     the arity is wrong. */
+     the arity is wrong and an error needs to be reported using
+     the original wrapper. */
   mz_prepare(2);
   jit_movi_i(JIT_R0, num_rands);
   jit_pusharg_i(JIT_R0); /* argc */