diff --git a/ChangeLog b/ChangeLog
index 0a5ef4ade8..34fca5bbeb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Thu Aug 25 07:00:00 2011  Koichi Sasada  <ko1@atdot.net>
+
+	* vm_insnhelper.h, vm_insnhelper.c, vm.c, vm_method.c, insns.def:
+	  Manage a redefinition of special methods for each classes.
+	  A patch from Joel Gouly <joel.gouly@gmail.com>.  Thanks!
+
 Thu Aug 25 06:51:08 2011  Aaron Patterson <aaron@tenderlovemaking.com>
 
 	* ext/psych/lib/psych.rb: Fixing psych version number.
diff --git a/insns.def b/insns.def
index 0541b344f9..32cb650b16 100644
--- a/insns.def
+++ b/insns.def
@@ -1282,7 +1282,11 @@ opt_case_dispatch
       case T_FIXNUM:
       case T_BIGNUM:
       case T_STRING:
-	if (BASIC_OP_UNREDEFINED_P(BOP_EQQ)) {
+	if (BASIC_OP_UNREDEFINED_P(BOP_EQQ,
+				   SYMBOL_REDEFINED_OP_FLAG |
+				   FIXNUM_REDEFINED_OP_FLAG |
+				   BIGNUM_REDEFINED_OP_FLAG |
+				   STRING_REDEFINED_OP_FLAG)) {
 	    st_data_t val;
 	    if (st_lookup(RHASH_TBL(hash), key, &val)) {
 		JUMP(FIX2INT((VALUE)val));
@@ -1335,7 +1339,7 @@ opt_plus
     }
 #if 1
     else if (FIXNUM_2_P(recv, obj) &&
-	     BASIC_OP_UNREDEFINED_P(BOP_PLUS)) {
+	     BASIC_OP_UNREDEFINED_P(BOP_PLUS,FIXNUM_REDEFINED_OP_FLAG)) {
 	/* fixnum + fixnum */
 #ifndef LONG_LONG_VALUE
 	val = (recv + (obj & (~1)));
@@ -1365,7 +1369,7 @@ opt_plus
 #if 1
 	else if (HEAP_CLASS_OF(recv) == rb_cFloat &&
 		 HEAP_CLASS_OF(obj) == rb_cFloat &&
-		 BASIC_OP_UNREDEFINED_P(BOP_PLUS)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_PLUS, FLOAT_REDEFINED_OP_FLAG)) {
 	    val = DBL2NUM(RFLOAT_VALUE(recv) + RFLOAT_VALUE(obj));
 	}
 #endif
@@ -1373,13 +1377,13 @@ opt_plus
 #if 1
 	else if (HEAP_CLASS_OF(recv) == rb_cString &&
 		 HEAP_CLASS_OF(obj) == rb_cString &&
-		 BASIC_OP_UNREDEFINED_P(BOP_PLUS)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_PLUS, STRING_REDEFINED_OP_FLAG)) {
 	    val = rb_str_plus(recv, obj);
 	}
 #endif
 #if 1
 	else if (HEAP_CLASS_OF(recv) == rb_cArray &&
-		 BASIC_OP_UNREDEFINED_P(BOP_PLUS)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_PLUS, ARRAY_REDEFINED_OP_FLAG)) {
 	    val = rb_ary_plus(recv, obj);
 	}
 #endif
@@ -1407,7 +1411,7 @@ opt_minus
 (VALUE val)
 {
     if (FIXNUM_2_P(recv, obj) &&
-	BASIC_OP_UNREDEFINED_P(BOP_MINUS)) {
+	BASIC_OP_UNREDEFINED_P(BOP_MINUS, FIXNUM_REDEFINED_OP_FLAG)) {
 	long a, b, c;
 
 	a = FIX2LONG(recv);
@@ -1427,7 +1431,7 @@ opt_minus
 #if 1
 	else if (HEAP_CLASS_OF(recv) == rb_cFloat &&
 		 HEAP_CLASS_OF(obj) == rb_cFloat  &&
-		 BASIC_OP_UNREDEFINED_P(BOP_MINUS)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_MINUS, FLOAT_REDEFINED_OP_FLAG)) {
 	    val = DBL2NUM(RFLOAT_VALUE(recv) - RFLOAT_VALUE(obj));
 	}
 #endif
@@ -1456,7 +1460,7 @@ opt_mult
 (VALUE val)
 {
     if (FIXNUM_2_P(recv, obj) &&
-	BASIC_OP_UNREDEFINED_P(BOP_MULT)) {
+	BASIC_OP_UNREDEFINED_P(BOP_MULT, FIXNUM_REDEFINED_OP_FLAG)) {
 	long a, b;
 
 	a = FIX2LONG(recv);
@@ -1482,7 +1486,7 @@ opt_mult
 #if 1
 	else if (HEAP_CLASS_OF(recv) == rb_cFloat &&
 		 HEAP_CLASS_OF(obj) == rb_cFloat  &&
-		 BASIC_OP_UNREDEFINED_P(BOP_MULT)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_MULT, FLOAT_REDEFINED_OP_FLAG)) {
 	    val = DBL2NUM(RFLOAT_VALUE(recv) * RFLOAT_VALUE(obj));
 	}
 #endif
@@ -1510,7 +1514,7 @@ opt_div
 (VALUE val)
 {
     if (FIXNUM_2_P(recv, obj) &&
-	BASIC_OP_UNREDEFINED_P(BOP_DIV)) {
+	BASIC_OP_UNREDEFINED_P(BOP_DIV, FIXNUM_REDEFINED_OP_FLAG)) {
 	long x, y, div;
 
 	x = FIX2LONG(recv);
@@ -1546,7 +1550,7 @@ opt_div
 #if 1
 	else if (HEAP_CLASS_OF(recv) == rb_cFloat &&
 		 HEAP_CLASS_OF(obj) == rb_cFloat  &&
-		 BASIC_OP_UNREDEFINED_P(BOP_DIV)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_DIV, FLOAT_REDEFINED_OP_FLAG)) {
 	    val = DBL2NUM(RFLOAT_VALUE(recv) / RFLOAT_VALUE(obj));
 	}
 #endif
@@ -1574,7 +1578,7 @@ opt_mod
 (VALUE val)
 {
     if (FIXNUM_2_P(recv, obj) &&
-	BASIC_OP_UNREDEFINED_P(BOP_MOD)) {
+	BASIC_OP_UNREDEFINED_P(BOP_MOD, FIXNUM_REDEFINED_OP_FLAG )) {
 	long x, y, mod;
 
 	x = FIX2LONG(recv);
@@ -1610,7 +1614,7 @@ opt_mod
 	}
 	else if (HEAP_CLASS_OF(recv) == rb_cFloat &&
 		 HEAP_CLASS_OF(obj) == rb_cFloat &&
-		 BASIC_OP_UNREDEFINED_P(BOP_MOD)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_MOD, FLOAT_REDEFINED_OP_FLAG)) {
 	    double x = RFLOAT_VALUE(recv);
 	    double y = RFLOAT_VALUE(obj);
 	    double div, mod;
@@ -1705,7 +1709,7 @@ opt_lt
 (VALUE val)
 {
     if (FIXNUM_2_P(recv, obj) &&
-	BASIC_OP_UNREDEFINED_P(BOP_LT)) {
+	BASIC_OP_UNREDEFINED_P(BOP_LT, FIXNUM_REDEFINED_OP_FLAG)) {
 	SIGNED_VALUE a = recv, b = obj;
 
 	if (a < b) {
@@ -1721,7 +1725,7 @@ opt_lt
 #if 1
 	else if (HEAP_CLASS_OF(recv) == rb_cFloat &&
 		 HEAP_CLASS_OF(obj) == rb_cFloat  &&
-		 BASIC_OP_UNREDEFINED_P(BOP_LT)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_LT, FLOAT_REDEFINED_OP_FLAG)) {
 	    double a = RFLOAT_VALUE(recv);
 	    double b = RFLOAT_VALUE(obj);
 #if defined(_MSC_VER) && _MSC_VER < 1300
@@ -1755,7 +1759,7 @@ opt_le
 (VALUE val)
 {
     if (FIXNUM_2_P(recv, obj) &&
-	BASIC_OP_UNREDEFINED_P(BOP_LE)) {
+	BASIC_OP_UNREDEFINED_P(BOP_LE, FIXNUM_REDEFINED_OP_FLAG)) {
 	SIGNED_VALUE a = recv, b = obj;
 
 	if (a <= b) {
@@ -1785,7 +1789,7 @@ opt_gt
 (VALUE val)
 {
     if (FIXNUM_2_P(recv, obj) &&
-	BASIC_OP_UNREDEFINED_P(BOP_GT)) {
+	BASIC_OP_UNREDEFINED_P(BOP_GT, FIXNUM_REDEFINED_OP_FLAG)) {
 	SIGNED_VALUE a = recv, b = obj;
 
 	if (a > b) {
@@ -1801,7 +1805,7 @@ opt_gt
 #if 1
 	else if (HEAP_CLASS_OF(recv) == rb_cFloat &&
 		 HEAP_CLASS_OF(obj) == rb_cFloat  &&
-		 BASIC_OP_UNREDEFINED_P(BOP_GT)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_GT, FLOAT_REDEFINED_OP_FLAG)) {
 	    double a = RFLOAT_VALUE(recv);
 	    double b = RFLOAT_VALUE(obj);
 #if defined(_MSC_VER) && _MSC_VER < 1300
@@ -1835,7 +1839,7 @@ opt_ge
 (VALUE val)
 {
     if (FIXNUM_2_P(recv, obj) &&
-	BASIC_OP_UNREDEFINED_P(BOP_GE)) {
+	BASIC_OP_UNREDEFINED_P(BOP_GE, FIXNUM_REDEFINED_OP_FLAG)) {
 	SIGNED_VALUE a = recv, b = obj;
 
 	if (a >= b) {
@@ -1867,11 +1871,11 @@ opt_ltlt
 	if (0) {
 	}
 	else if (HEAP_CLASS_OF(recv) == rb_cString &&
-		 BASIC_OP_UNREDEFINED_P(BOP_LTLT)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_LTLT, STRING_REDEFINED_OP_FLAG)) {
 	    val = rb_str_concat(recv, obj);
 	}
 	else if (HEAP_CLASS_OF(recv) == rb_cArray &&
-		 BASIC_OP_UNREDEFINED_P(BOP_LTLT)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_LTLT, ARRAY_REDEFINED_OP_FLAG)) {
 	    val = rb_ary_push(recv, obj);
 	}
 	else {
@@ -1897,11 +1901,11 @@ opt_aref
 (VALUE recv, VALUE obj)
 (VALUE val)
 {
-    if (!SPECIAL_CONST_P(recv) && BASIC_OP_UNREDEFINED_P(BOP_AREF)) {
-	if (HEAP_CLASS_OF(recv) == rb_cArray && FIXNUM_P(obj)) {
+    if (!SPECIAL_CONST_P(recv)) {
+	if (HEAP_CLASS_OF(recv) == rb_cArray && BASIC_OP_UNREDEFINED_P(BOP_AREF, ARRAY_REDEFINED_OP_FLAG) && FIXNUM_P(obj)) {
 	    val = rb_ary_entry(recv, FIX2LONG(obj));
 	}
-	else if (HEAP_CLASS_OF(recv) == rb_cHash) {
+	else if (HEAP_CLASS_OF(recv) == rb_cHash && BASIC_OP_UNREDEFINED_P(BOP_AREF, HASH_REDEFINED_OP_FLAG)) {
 	    val = rb_hash_aref(recv, obj);
 	}
 	else {
@@ -1927,13 +1931,12 @@ opt_aset
 (VALUE recv, VALUE obj, VALUE set)
 (VALUE val)
 {
-    if (!SPECIAL_CONST_P(recv) &&
-	BASIC_OP_UNREDEFINED_P(BOP_ASET)) {
-	if (HEAP_CLASS_OF(recv) == rb_cArray && FIXNUM_P(obj)) {
+    if (!SPECIAL_CONST_P(recv)) {
+	if (HEAP_CLASS_OF(recv) == rb_cArray && BASIC_OP_UNREDEFINED_P(BOP_ASET, ARRAY_REDEFINED_OP_FLAG) && FIXNUM_P(obj)) {
 	    rb_ary_store(recv, FIX2LONG(obj), set);
 	    val = set;
 	}
-	else if (HEAP_CLASS_OF(recv) == rb_cHash) {
+	else if (HEAP_CLASS_OF(recv) == rb_cHash && BASIC_OP_UNREDEFINED_P(BOP_ASET, HASH_REDEFINED_OP_FLAG)) {
 	    rb_hash_aset(recv, obj, set);
 	    val = set;
 	}
@@ -1961,15 +1964,17 @@ opt_length
 (VALUE recv)
 (VALUE val)
 {
-    if (LIKELY(!SPECIAL_CONST_P(recv) &&
-	       BASIC_OP_UNREDEFINED_P(BOP_LENGTH))) {
-	if (HEAP_CLASS_OF(recv) == rb_cString) {
+    if (!SPECIAL_CONST_P(recv)) {
+	if (HEAP_CLASS_OF(recv) == rb_cString &&
+	    BASIC_OP_UNREDEFINED_P(BOP_LENGTH, STRING_REDEFINED_OP_FLAG)) {
 	    val = rb_str_length(recv);
 	}
-	else if (HEAP_CLASS_OF(recv) == rb_cArray) {
+	else if (HEAP_CLASS_OF(recv) == rb_cArray &&
+		 BASIC_OP_UNREDEFINED_P(BOP_LENGTH, ARRAY_REDEFINED_OP_FLAG)) {
 	    val = LONG2NUM(RARRAY_LEN(recv));
 	}
-	else if (HEAP_CLASS_OF(recv) == rb_cHash) {
+	else if (HEAP_CLASS_OF(recv) == rb_cHash &&
+		 BASIC_OP_UNREDEFINED_P(BOP_LENGTH, HASH_REDEFINED_OP_FLAG)) {
 	    val = INT2FIX(RHASH_SIZE(recv));
 	}
 	else {
@@ -1994,15 +1999,17 @@ opt_size
 (VALUE recv)
 (VALUE val)
 {
-    if (LIKELY(BASIC_OP_UNREDEFINED_P(BOP_SIZE) &&
-	       !SPECIAL_CONST_P(recv))) {
-	if (HEAP_CLASS_OF(recv) == rb_cString) {
+    if (!SPECIAL_CONST_P(recv)) {
+	if (HEAP_CLASS_OF(recv) == rb_cString &&
+	    BASIC_OP_UNREDEFINED_P(BOP_SIZE, STRING_REDEFINED_OP_FLAG)) {
 	    val = rb_str_length(recv);
 	}
-	else if (HEAP_CLASS_OF(recv) == rb_cArray) {
+	else if (HEAP_CLASS_OF(recv) == rb_cArray &&
+		 BASIC_OP_UNREDEFINED_P(BOP_SIZE, ARRAY_REDEFINED_OP_FLAG)) {
 	    val = LONG2NUM(RARRAY_LEN(recv));
 	}
-	else if (HEAP_CLASS_OF(recv) == rb_cHash) {
+	else if (HEAP_CLASS_OF(recv) == rb_cHash &&
+		 BASIC_OP_UNREDEFINED_P(BOP_SIZE, HASH_REDEFINED_OP_FLAG)) {
 	    val = INT2FIX(RHASH_SIZE(recv));
 	}
 	else {
@@ -2029,7 +2036,7 @@ opt_succ
 {
     if (SPECIAL_CONST_P(recv)) {
 	if (FIXNUM_P(recv) &&
-	    BASIC_OP_UNREDEFINED_P(BOP_SUCC)) {
+	    BASIC_OP_UNREDEFINED_P(BOP_SUCC, FIXNUM_REDEFINED_OP_FLAG)) {
 	    const VALUE obj = INT2FIX(1);
 	    /* fixnum + INT2FIX(1) */
 	    val = (recv + (obj & (~1)));
@@ -2044,11 +2051,11 @@ opt_succ
     }
     else {
 	if (HEAP_CLASS_OF(recv) == rb_cString &&
-	    BASIC_OP_UNREDEFINED_P(BOP_SUCC)) {
+	    BASIC_OP_UNREDEFINED_P(BOP_SUCC, STRING_REDEFINED_OP_FLAG)) {
 	    val = rb_str_succ(recv);
 	}
 	else if (HEAP_CLASS_OF(recv) == rb_cTime &&
-		 BASIC_OP_UNREDEFINED_P(BOP_SUCC)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_SUCC, TIME_REDEFINED_OP_FLAG)) {
 	    val = rb_time_succ(recv);
 	}
 	else
diff --git a/vm.c b/vm.c
index bacb5ed7d3..70c46957db 100644
--- a/vm.c
+++ b/vm.c
@@ -976,12 +976,23 @@ rb_iter_break(void)
 static st_table *vm_opt_method_table = 0;
 
 static void
-rb_vm_check_redefinition_opt_method(const rb_method_entry_t *me)
+rb_vm_check_redefinition_opt_method(const rb_method_entry_t *me, VALUE klass)
 {
     st_data_t bop;
     if (!me->def || me->def->type == VM_METHOD_TYPE_CFUNC) {
 	if (st_lookup(vm_opt_method_table, (st_data_t)me, &bop)) {
-	    ruby_vm_redefined_flag[bop] = 1;
+	    int flag = 0;
+
+	    if      (klass == rb_cFixnum) flag = FIXNUM_REDEFINED_OP_FLAG;
+	    else if (klass == rb_cFloat)  flag = FLOAT_REDEFINED_OP_FLAG;
+	    else if (klass == rb_cString) flag = STRING_REDEFINED_OP_FLAG;
+	    else if (klass == rb_cArray)  flag = ARRAY_REDEFINED_OP_FLAG;
+	    else if (klass == rb_cHash)   flag = HASH_REDEFINED_OP_FLAG;
+	    else if (klass == rb_cBignum) flag = BIGNUM_REDEFINED_OP_FLAG;
+	    else if (klass == rb_cSymbol) flag = SYMBOL_REDEFINED_OP_FLAG;
+	    else if (klass == rb_cTime)   flag = TIME_REDEFINED_OP_FLAG;
+
+	    ruby_vm_redefined_flag[bop] |= flag;
 	}
     }
 }
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index 918c7fb7de..9410963d5c 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -1696,13 +1696,13 @@ VALUE
 opt_eq_func(VALUE recv, VALUE obj, IC ic)
 {
     if (FIXNUM_2_P(recv, obj) &&
-	BASIC_OP_UNREDEFINED_P(BOP_EQ)) {
+	BASIC_OP_UNREDEFINED_P(BOP_EQ, FIXNUM_REDEFINED_OP_FLAG)) {
 	return (recv == obj) ? Qtrue : Qfalse;
     }
     else if (!SPECIAL_CONST_P(recv) && !SPECIAL_CONST_P(obj)) {
 	if (HEAP_CLASS_OF(recv) == rb_cFloat &&
 		 HEAP_CLASS_OF(obj) == rb_cFloat &&
-		 BASIC_OP_UNREDEFINED_P(BOP_EQ)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_EQ, FLOAT_REDEFINED_OP_FLAG)) {
 	    double a = RFLOAT_VALUE(recv);
 	    double b = RFLOAT_VALUE(obj);
 
@@ -1713,7 +1713,7 @@ opt_eq_func(VALUE recv, VALUE obj, IC ic)
 	}
 	else if (HEAP_CLASS_OF(recv) == rb_cString &&
 		 HEAP_CLASS_OF(obj) == rb_cString &&
-		 BASIC_OP_UNREDEFINED_P(BOP_EQ)) {
+		 BASIC_OP_UNREDEFINED_P(BOP_EQ, STRING_REDEFINED_OP_FLAG)) {
 	    return rb_str_equal(recv, obj);
 	}
     }
diff --git a/vm_insnhelper.h b/vm_insnhelper.h
index 1b352937fe..018adb6d5b 100644
--- a/vm_insnhelper.h
+++ b/vm_insnhelper.h
@@ -184,8 +184,17 @@ extern VALUE ruby_vm_const_missing_count;
 /**********************************************************/
 
 /* optimize insn */
+#define FIXNUM_REDEFINED_OP_FLAG (1 << 0)
+#define FLOAT_REDEFINED_OP_FLAG  (1 << 1)
+#define STRING_REDEFINED_OP_FLAG (1 << 2)
+#define ARRAY_REDEFINED_OP_FLAG  (1 << 3)
+#define HASH_REDEFINED_OP_FLAG   (1 << 4)
+#define BIGNUM_REDEFINED_OP_FLAG (1 << 5)
+#define SYMBOL_REDEFINED_OP_FLAG (1 << 6)
+#define TIME_REDEFINED_OP_FLAG   (1 << 7)
+
 #define FIXNUM_2_P(a, b) ((a) & (b) & 1)
-#define BASIC_OP_UNREDEFINED_P(op) (LIKELY(ruby_vm_redefined_flag[(op)] == 0))
+#define BASIC_OP_UNREDEFINED_P(op, klass) (LIKELY((ruby_vm_redefined_flag[(op)]&(klass)) == 0))
 #define HEAP_CLASS_OF(obj) RBASIC(obj)->klass
 
 #ifndef USE_IC_FOR_SPECIALIZED_METHOD
diff --git a/vm_method.c b/vm_method.c
index 608760f2ad..d6c4926e65 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -6,7 +6,7 @@
 #define CACHE_MASK 0x7ff
 #define EXPR1(c,m) ((((c)>>3)^(m))&CACHE_MASK)
 
-static void rb_vm_check_redefinition_opt_method(const rb_method_entry_t *me);
+static void rb_vm_check_redefinition_opt_method(const rb_method_entry_t *me, VALUE klass);
 
 static ID object_id, respond_to_missing;
 static ID removed, singleton_removed, undefined, singleton_undefined;
@@ -195,7 +195,7 @@ rb_method_entry_make(VALUE klass, ID mid, rb_method_type_t type,
 	rb_method_definition_t *old_def = old_me->def;
 
 	if (rb_method_definition_eq(old_def, def)) return old_me;
-	rb_vm_check_redefinition_opt_method(old_me);
+	rb_vm_check_redefinition_opt_method(old_me, klass);
 
 	if (RTEST(ruby_verbose) &&
 	    type != VM_METHOD_TYPE_UNDEF &&
@@ -452,7 +452,7 @@ remove_method(VALUE klass, ID mid)
     key = (st_data_t)mid;
     st_delete(RCLASS_M_TBL(klass), &key, &data);
 
-    rb_vm_check_redefinition_opt_method(me);
+    rb_vm_check_redefinition_opt_method(me, klass);
     rb_clear_cache_for_undef(klass, mid);
     rb_unlink_method_entry(me);
 
@@ -530,7 +530,7 @@ rb_export_method(VALUE klass, ID name, rb_method_flag_t noex)
     }
 
     if (me->flag != noex) {
-	rb_vm_check_redefinition_opt_method(me);
+	rb_vm_check_redefinition_opt_method(me, klass);
 
 	if (klass == me->klass) {
 	    me->flag = noex;