vm_insnhelper.c: merge opt_eq_func / opt_eql_func

These two function were almost identical, except in case of
T_STRING/T_FLOAT. Why not merge them into one, and let the difference be
handled in normal method calls (slowpath).  This does not improve
runtime performance for me, but at least reduces for instance rb_eql_opt
from 653 bytes to 86 bytes on my machine, according to nm(1).

insns.def

@@ -1168,7 +1168,7 @@ opt_eq
 (VALUE recv, VALUE obj)
 (VALUE val)
 {
-    val = opt_eq_func(GET_ISEQ(), recv, obj, cd);
+    val = opt_equality(GET_ISEQ(), recv, obj, cd);
 
     if (val == Qundef) {
         CALL_SIMPLE_METHOD();

vm_insnhelper.c

@@ -1669,17 +1669,6 @@ vm_method_cfunc_is(const rb_iseq_t *iseq, CALL_DATA cd, VALUE recv, VALUE (*func
     return check_cfunc(vm_cc_cme(cd->cc), func);
 }
 
-static VALUE
-opt_equal_fallback(const rb_iseq_t *iseq, VALUE recv, VALUE obj, CALL_DATA cd)
-{
-    if (vm_method_cfunc_is(iseq, cd, recv, rb_obj_equal)) {
-	return recv == obj ? Qtrue : Qfalse;
-    }
-
-    return Qundef;
-}
-
-#define BUILTIN_CLASS_P(x, k) (!SPECIAL_CONST_P(x) && RBASIC_CLASS(x) == k)
 #define EQ_UNREDEFINED_P(t) BASIC_OP_UNREDEFINED_P(BOP_EQ, t##_REDEFINED_OP_FLAG)
 
 static inline bool
@@ -1711,83 +1700,64 @@ FLONUM_2_P(VALUE a, VALUE b)
 #endif
 }
 
-/* 1: compare by identity, 0: not applicable, -1: redefined */
-static inline int
-comparable_by_identity(VALUE recv, VALUE obj)
+static VALUE
+opt_equality(const rb_iseq_t *cd_owner, VALUE recv, VALUE obj, CALL_DATA cd)
 {
-    if (FIXNUM_2_P(recv, obj)) {
-	return (EQ_UNREDEFINED_P(INTEGER) != 0) * 2 - 1;
+    if (FIXNUM_2_P(recv, obj) && EQ_UNREDEFINED_P(INTEGER)) {
+        goto compare_by_identity;
     }
-    if (FLONUM_2_P(recv, obj)) {
-	return (EQ_UNREDEFINED_P(FLOAT) != 0) * 2 - 1;
+    else if (FLONUM_2_P(recv, obj) && EQ_UNREDEFINED_P(FLOAT)) {
+        goto compare_by_identity;
     }
-    if (SYMBOL_P(recv) && SYMBOL_P(obj)) {
-	return (EQ_UNREDEFINED_P(SYMBOL) != 0) * 2 - 1;
+    else if (STATIC_SYM_P(recv) && STATIC_SYM_P(obj) && EQ_UNREDEFINED_P(SYMBOL)) {
+        goto compare_by_identity;
     }
-    return 0;
-}
+    else if (SPECIAL_CONST_P(recv)) {
+        goto compare_by_funcall;
+    }
+    else if (RBASIC_CLASS(recv) == rb_cFloat && RB_FLOAT_TYPE_P(obj) && EQ_UNREDEFINED_P(FLOAT)) {
+        double a = RFLOAT_VALUE(recv);
+        double b = RFLOAT_VALUE(obj);
 
-static
-#ifndef NO_BIG_INLINE
-inline
+#if MSC_VERSION_BEFORE(1300)
+        if (isnan(a)) {
+            return Qfalse;
+        }
+        else if (isnan(b)) {
+            return Qfalse;
+        }
+        else
 #endif
-VALUE
-opt_eq_func(const rb_iseq_t *iseq, VALUE recv, VALUE obj, CALL_DATA cd)
-{
-    switch (comparable_by_identity(recv, obj)) {
-      case 1:
-	return (recv == obj) ? Qtrue : Qfalse;
-      case -1:
-	goto fallback;
+        if (a == b) {
+            return Qtrue;
+        }
+        else {
+            return Qfalse;
+        }
     }
-    if (0) {
-    }
-    else if (BUILTIN_CLASS_P(recv, rb_cFloat)) {
-	if (EQ_UNREDEFINED_P(FLOAT)) {
-	    return rb_float_equal(recv, obj);
-	}
-    }
-    else if (BUILTIN_CLASS_P(recv, rb_cString) && EQ_UNREDEFINED_P(STRING)) {
-        if (recv == obj) return Qtrue;
-        if (RB_TYPE_P(obj, T_STRING)) {
-            return rb_str_eql_internal(recv, obj);
+    else if (RBASIC_CLASS(recv) == rb_cString && EQ_UNREDEFINED_P(STRING)) {
+        if (recv == obj) {
+            return Qtrue;
+        }
+        else if (RB_TYPE_P(obj, T_STRING)) {
+            return rb_str_eql_internal(obj, recv);
         }
     }
 
-  fallback:
-    return opt_equal_fallback(iseq, recv, obj, cd);
-}
-
-static
-#ifndef NO_BIG_INLINE
-inline
-#endif
-VALUE
-opt_eql_func(VALUE recv, VALUE obj, CALL_DATA cd)
-{
-    switch (comparable_by_identity(recv, obj)) {
-      case 1:
-	return (recv == obj) ? Qtrue : Qfalse;
-      case -1:
-	goto fallback;
-    }
-    if (0) {
-    }
-    else if (BUILTIN_CLASS_P(recv, rb_cFloat)) {
-	if (EQ_UNREDEFINED_P(FLOAT)) {
-	    return rb_float_eql(recv, obj);
-	}
-    }
-    else if (BUILTIN_CLASS_P(recv, rb_cString)) {
-	if (EQ_UNREDEFINED_P(STRING)) {
-	    return rb_str_eql(recv, obj);
-	}
+  compare_by_funcall:
+    if (! vm_method_cfunc_is(cd_owner, cd, recv, rb_obj_equal)) {
+        return Qundef;
     }
 
-  fallback:
-    return opt_equal_fallback(NULL, recv, obj, cd);
+  compare_by_identity:
+    if (recv == obj) {
+        return Qtrue;
+    }
+    else {
+        return Qfalse;
+    }
 }
-#undef BUILTIN_CLASS_P
+
 #undef EQ_UNREDEFINED_P
 
 #define vm_ci_new_id(mid) vm_ci_new_runtime(mid, 0, 0, NULL)
@@ -1802,14 +1772,14 @@ rb_equal_opt(VALUE obj1, VALUE obj2)
     }
 
     struct rb_call_data cd = { .ci = ci, .cc = vm_cc_empty() };
-    return opt_eq_func(NULL, obj1, obj2, &cd);
+    return opt_equality(NULL, obj1, obj2, &cd);
 }
 
 VALUE
 rb_eql_opt(VALUE obj1, VALUE obj2)
 {
     struct rb_call_data cd = { .ci = vm_ci_new_id(idEqlP), .cc = vm_cc_empty() };
-    return opt_eql_func(obj1, obj2, &cd);
+    return opt_equality(NULL, obj1, obj2, &cd);
 }
 
 extern VALUE rb_vm_call0(rb_execution_context_t *ec, VALUE, ID, int, const VALUE*, const rb_callable_method_entry_t *, int kw_splat);
@@ -4448,7 +4418,7 @@ static VALUE
 vm_opt_neq(const rb_iseq_t *iseq, CALL_DATA cd, CALL_DATA cd_eq, VALUE recv, VALUE obj)
 {
     if (vm_method_cfunc_is(iseq, cd, recv, rb_obj_not_equal)) {
-        VALUE val = opt_eq_func(iseq, recv, obj, cd_eq);
+        VALUE val = opt_equality(iseq, recv, obj, cd_eq);
 
 	if (val != Qundef) {
 	    return RTEST(val) ? Qfalse : Qtrue;