Merge: Callref compilers
[nit.git] / src / interpreter / naive_interpreter.nit
index 3d3aa12..7557da7 100644 (file)
@@ -21,11 +21,12 @@ import literal
 import semantize
 private import parser::tables
 import mixin
-import primitive_types
+private import model::serialize_model
+private import frontend::explain_assert_api
 
 redef class ToolContext
        # --discover-call-trace
-       var opt_discover_call_trace = new OptionBool("Trace calls of the first invocation of a method", "--discover-call-trace")
+       var opt_discover_call_trace = new OptionBool("Trace calls of the first invocation of methods", "--discover-call-trace")
 
        redef init
        do
@@ -60,7 +61,7 @@ class NaiveInterpreter
        var modelbuilder: ModelBuilder
 
        # The main module of the program (used to lookup method)
-       var mainmodule: MModule
+       var mainmodule: MModule is writable
 
        # The command line arguments of the interpreted program
        # arguments.first is the program name
@@ -70,6 +71,9 @@ class NaiveInterpreter
        # The main Sys instance
        var mainobj: nullable Instance is noinit
 
+       # Name of all supported functional names
+       var routine_types: Set[String] = new HashSet[String]
+
        init
        do
                if mainmodule.model.get_mclasses_by_name("Bool") != null then
@@ -79,6 +83,15 @@ class NaiveInterpreter
                        init_instance_primitive(self.false_instance)
                end
                self.null_instance = new PrimitiveInstance[nullable Object](mainmodule.model.null_type, null)
+
+               routine_types.add("RoutineRef")
+               for name in ["Proc", "Fun", "ProcRef", "FunRef"] do
+                       # 20 is a magic number = upper limit of the arity of each functional class.
+                       # i.e. Proc0, Proc1, ... Proc19
+                       for i  in [0..20[ do
+                               routine_types.add("{name}{i}")
+                       end
+               end
        end
 
        # Starts the interpreter on the main module of a program
@@ -113,17 +126,19 @@ class NaiveInterpreter
                return self.modelbuilder.force_get_primitive_method(current_node, name, recv.mclass, self.mainmodule)
        end
 
-       # Is a return executed?
-       # Set this mark to skip the evaluation until the end of the specified method frame
-       var returnmark: nullable FRAME = null
-
-       # Is a break or a continue executed?
+       # Is a return, a break or a continue executed?
        # Set this mark to skip the evaluation until a labeled statement catch it with `is_escape`
        var escapemark: nullable EscapeMark = null
 
+       # The count of `catch` blocs that have been encountered and can catch an abort
+       var catch_count = 0 is writable
+
+       # The last error thrown on abort/runtime error where catch_count > 0
+       var last_error: nullable FatalError = null
+
        # Is a return or a break or a continue executed?
        # Use this function to know if you must skip the evaluation of statements
-       fun is_escaping: Bool do return returnmark != null or escapemark != null
+       fun is_escaping: Bool do return escapemark != null
 
        # The value associated with the current return/break/continue, if any.
        # Set the value when you set a escapemark.
@@ -157,7 +172,7 @@ class NaiveInterpreter
                        n.debug("inconsitance: no value and not escaping.")
                end
                var implicit_cast_to = n.implicit_cast_to
-               if implicit_cast_to != null then
+               if i != null and implicit_cast_to != null then
                        var mtype = self.unanchor_type(implicit_cast_to)
                        if not self.is_subtype(i.mtype, mtype) then n.fatal(self, "Cast failed. Expected `{implicit_cast_to}`, got `{i.mtype}`")
                end
@@ -216,6 +231,51 @@ class NaiveInterpreter
                return instance
        end
 
+       # Return the int8 instance associated with `val`.
+       fun int8_instance(val: Int8): Instance
+       do
+               var t = mainmodule.int8_type
+               var instance = new PrimitiveInstance[Int8](t, val)
+               init_instance_primitive(instance)
+               return instance
+       end
+
+       # Return the int16 instance associated with `val`.
+       fun int16_instance(val: Int16): Instance
+       do
+               var t = mainmodule.int16_type
+               var instance = new PrimitiveInstance[Int16](t, val)
+               init_instance_primitive(instance)
+               return instance
+       end
+
+       # Return the uint16 instance associated with `val`.
+       fun uint16_instance(val: UInt16): Instance
+       do
+               var t = mainmodule.uint16_type
+               var instance = new PrimitiveInstance[UInt16](t, val)
+               init_instance_primitive(instance)
+               return instance
+       end
+
+       # Return the int32 instance associated with `val`.
+       fun int32_instance(val: Int32): Instance
+       do
+               var t = mainmodule.int32_type
+               var instance = new PrimitiveInstance[Int32](t, val)
+               init_instance_primitive(instance)
+               return instance
+       end
+
+       # Return the uint32 instance associated with `val`.
+       fun uint32_instance(val: UInt32): Instance
+       do
+               var t = mainmodule.uint32_type
+               var instance = new PrimitiveInstance[UInt32](t, val)
+               init_instance_primitive(instance)
+               return instance
+       end
+
        # Return the char instance associated with `val`.
        fun char_instance(val: Char): Instance
        do
@@ -272,24 +332,46 @@ class NaiveInterpreter
                end
        end
 
-       # Return a new native string initialized with `txt`
-       fun native_string_instance(txt: String): Instance
+       # Return a new C string initialized with `txt`
+       fun c_string_instance(txt: String): Instance
        do
-               var instance = native_string_instance_len(txt.bytelen+1)
+               var instance = c_string_instance_len(txt.byte_length+1)
                var val = instance.val
-               val[txt.bytelen] = 0u8
-               txt.to_cstring.copy_to(val, txt.bytelen, 0, 0)
+               val[txt.byte_length] = 0
+               txt.to_cstring.copy_to(val, txt.byte_length, 0, 0)
 
                return instance
        end
 
-       # Return a new native string initialized of `length`
-       fun native_string_instance_len(length: Int): PrimitiveInstance[NativeString]
+       # Return a new C string initialized with `txt`
+       fun c_string_instance_from_ns(txt: CString, len: Int): Instance
        do
-               var val = new NativeString(length)
+               var instance = c_string_instance_len(len)
+               var val = instance.val
+               txt.copy_to(val, len, 0, 0)
+
+               return instance
+       end
 
-               var t = mainmodule.native_string_type
-               var instance = new PrimitiveInstance[NativeString](t, val)
+       # Return a new C string instance sharing the same data space as `txt`
+       fun c_string_instance_fast_cstr(txt: CString, from: Int): Instance
+       do
+               var ncstr = txt.fast_cstring(from)
+               var t = mainmodule.c_string_type
+
+               var instance = new PrimitiveInstance[CString](t, ncstr)
+               init_instance_primitive(instance)
+
+               return instance
+       end
+
+       # Return a new C string initialized of `length`
+       fun c_string_instance_len(length: Int): PrimitiveInstance[CString]
+       do
+               var val = new CString(length)
+
+               var t = mainmodule.c_string_type
+               var instance = new PrimitiveInstance[CString](t, val)
                init_instance_primitive(instance)
                return instance
        end
@@ -297,8 +379,8 @@ class NaiveInterpreter
        # Return a new String instance for `txt`
        fun string_instance(txt: String): Instance
        do
-               var nat = native_string_instance(txt)
-               var res = self.send(self.force_get_primitive_method("to_s_with_length", nat.mtype), [nat, self.int_instance(txt.bytelen)])
+               var nat = c_string_instance(txt)
+               var res = self.send(self.force_get_primitive_method("to_s_unsafe", nat.mtype), [nat, self.int_instance(txt.byte_length), self.int_instance(txt.length), self.false_instance, self.false_instance])
                assert res != null
                return res
        end
@@ -386,6 +468,22 @@ class NaiveInterpreter
        # Store known methods, used to trace methods as they are reached
        var discover_call_trace: Set[MMethodDef] = new HashSet[MMethodDef]
 
+       # Consumes an iterator of expressions and tries to map each element to
+       # its corresponding Instance.
+       #
+       # If any AExprs doesn't resolve to an Instance, then it returns null.
+       # Otherwise return an array of instances
+       fun aexprs_to_instances(aexprs: Iterator[AExpr]): nullable Array[Instance]
+       do
+               var accumulator = new Array[Instance]
+               for aexpr in aexprs do
+                       var instance = expr(aexpr)
+                       if instance == null then return null
+                       accumulator.push(instance)
+               end
+               return accumulator
+       end
+
        # Evaluate `args` as expressions in the call of `mpropdef` on `recv`.
        # This method is used to manage varargs in signatures and returns the real array
        # of instances to use in the call.
@@ -400,22 +498,15 @@ class NaiveInterpreter
 
                if map == null then
                        assert args.length == msignature.arity else debug("Expected {msignature.arity} args, got {args.length}")
-                       for ne in args do
-                               var e = self.expr(ne)
-                               if e == null then return null
-                               res.add e
-                       end
+                       var rest_args = aexprs_to_instances(args.iterator)
+                       if rest_args == null then return null
+                       res.append(rest_args)
                        return res
                end
 
                # Eval in order of arguments, not parameters
-               var exprs = new Array[Instance].with_capacity(args.length)
-               for ne in args do
-                       var e = self.expr(ne)
-                       if e == null then return null
-                       exprs.add e
-               end
-
+               var exprs = aexprs_to_instances(args.iterator)
+               if exprs == null then return null
 
                # Fill `res` with the result of the evaluation according to the mapping
                for i in [0..msignature.arity[ do
@@ -426,8 +517,8 @@ class NaiveInterpreter
                                res.add(null_instance)
                                continue
                        end
-                       if param.is_vararg and map.vararg_decl > 0 then
-                               var vararg = exprs.sub(j, map.vararg_decl)
+                       if param.is_vararg and args[i].vararg_decl > 0 then
+                               var vararg = exprs.sub(j, args[i].vararg_decl)
                                var elttype = param.mtype.anchor_to(self.mainmodule, recv.mtype.as(MClassType))
                                var arg = self.array_instance(vararg, elttype)
                                res.add(arg)
@@ -481,10 +572,12 @@ class NaiveInterpreter
        # Execute type checks of covariant parameters
        fun parameter_check(node: ANode, mpropdef: MMethodDef, args: Array[Instance])
        do
-               var msignature = mpropdef.msignature
+               var msignature = mpropdef.msignature.as(not null)
                for i in [0..msignature.arity[ do
+                       var mp = msignature.mparameters[i]
+
                        # skip test for vararg since the array is instantiated with the correct polymorphic type
-                       if msignature.vararg_rank == i then continue
+                       if mp.is_vararg then continue
 
                        # skip if the cast is not required
                        var origmtype =  mpropdef.mproperty.intro.msignature.mparameters[i].mtype
@@ -493,7 +586,7 @@ class NaiveInterpreter
                        #print "{mpropdef}: {mpropdef.mproperty.intro.msignature.mparameters[i]}"
 
                        # get the parameter type
-                       var mtype = msignature.mparameters[i].mtype
+                       var mtype = mp.mtype
                        var anchor = args.first.mtype.as(MClassType)
                        var amtype = mtype.anchor_to(self.mainmodule, anchor)
                        if not args[i+1].mtype.is_subtype(self.mainmodule, anchor, amtype) then
@@ -521,6 +614,7 @@ class NaiveInterpreter
        # Use this method, instead of `send` to execute and control the additional behavior of the call-sites
        fun callsite(callsite: nullable CallSite, arguments: Array[Instance]): nullable Instance
        do
+               if callsite == null then return null
                var initializers = callsite.mpropdef.initializers
                if not initializers.is_empty then
                        var recv = arguments.first
@@ -627,17 +721,31 @@ class NaiveInterpreter
        var error_instance = new MutableInstance(modelbuilder.model.null_type) is lazy
 end
 
+# A runtime error
+class FatalError
+       # The error message
+       var message: String
+
+       # The problematic node, if any
+       var node: nullable ANode
+end
+
 # An instance represents a value of the executed program.
 abstract class Instance
        # The dynamic type of the instance
        # ASSERT: not self.mtype.is_anchored
        var mtype: MType
 
-       # return true if the instance is the true value.
-       # return false if the instance is the true value.
-       # else aborts
+       # Return `true` if the instance is the `true` value.
+       #
+       # Return `false` if the instance is the `false` value.
+       # Abort if the instance is not a boolean value.
        fun is_true: Bool do abort
 
+       # Return `true` if the instance is null.
+       # Return `false` otherwise.
+       fun is_null: Bool do return mtype isa MNullType
+
        # Return true if `self` IS `o` (using the Nit semantic of is)
        fun eq_is(o: Instance): Bool do return self.is_same_instance(o)
 
@@ -656,6 +764,26 @@ abstract class Instance
        # else aborts
        fun to_b: Byte do abort
 
+       # Return the integer value if the instance is a int8.
+       # else aborts
+       fun to_i8: Int8 do abort
+
+       # Return the integer value if the instance is a int16.
+       # else aborts
+       fun to_i16: Int16 do abort
+
+       # Return the integer value if the instance is a uint16.
+       # else aborts
+       fun to_u16: UInt16 do abort
+
+       # Return the integer value if the instance is a int32.
+       # else aborts
+       fun to_i32: Int32 do abort
+
+       # Return the integer value if the instance is a uint32.
+       # else aborts
+       fun to_u32: UInt32 do abort
+
        # The real value encapsulated if the instance is primitive.
        # Else aborts.
        fun val: nullable Object do abort
@@ -669,8 +797,29 @@ class MutableInstance
        var attributes: Map[MAttribute, Instance] = new HashMap[MAttribute, Instance]
 end
 
+# An instance with the original receiver and callsite (for function reference)
+class CallrefInstance
+       super Instance
+
+       # The original receiver
+       #
+       # ~~~nitish
+       # var a = new A
+       # var f = &a.toto # `a` is the original receiver
+       # ~~~
+       var recv: Instance
+
+       # The original callsite
+       #
+       # ~~~nitish
+       # var a = new A
+       # var f = &a.toto # `toto` is the original callsite
+       # ~~~
+       var callsite: CallSite
+end
+
 # Special instance to handle primitives values (int, bool, etc.)
-# The trick it just to encapsulate the <<real>> value
+# The trick is just to encapsulate the “real” value.
 class PrimitiveInstance[E]
        super Instance
 
@@ -703,6 +852,16 @@ class PrimitiveInstance[E]
        redef fun to_f do return val.as(Float)
 
        redef fun to_b do return val.as(Byte)
+
+       redef fun to_i8 do return val.as(Int8)
+
+       redef fun to_i16 do return val.as(Int16)
+
+       redef fun to_u16 do return val.as(UInt16)
+
+       redef fun to_i32 do return val.as(Int32)
+
+       redef fun to_u32 do return val.as(UInt32)
 end
 
 # Information about local variables in a running method
@@ -724,7 +883,7 @@ class InterpreterFrame
        super Frame
 
        # Mapping between a variable and the current value
-       private var map: Map[Variable, Instance] = new HashMap[Variable, Instance]
+       var map: Map[Variable, Instance] = new HashMap[Variable, Instance]
 end
 
 redef class ANode
@@ -732,7 +891,13 @@ redef class ANode
        # `v` is used to know if a colored message is displayed or not
        fun fatal(v: NaiveInterpreter, message: String)
        do
-               if v.modelbuilder.toolcontext.opt_no_color.value == true then
+               # Abort if there is a `catch` block
+               if v.catch_count > 0 then
+                       v.last_error = new FatalError(message, self)
+                       abort
+               end
+
+               if v.modelbuilder.toolcontext.opt_no_color.value then
                        sys.stderr.write("Runtime error: {message} ({location.file.filename}:{location.line_start})\n")
                else
                        sys.stderr.write("{location}: Runtime error: {message}\n{location.colored_line("0;31")}\n")
@@ -760,16 +925,17 @@ redef class AMethPropdef
                var f = v.new_frame(self, mpropdef, args)
                var res = call_commons(v, mpropdef, args, f)
                v.frames.shift
-               if v.returnmark == f then
-                       v.returnmark = null
+               if v.is_escape(self.return_mark) then
                        res = v.escapevalue
-                       v.escapevalue = null
                        return res
                end
                return res
        end
 
-       private fun call_commons(v: NaiveInterpreter, mpropdef: MMethodDef, arguments: Array[Instance], f: Frame): nullable Instance
+       # Execution of the body of the method
+       #
+       # It handle the common special cases: super, intern, extern
+       fun call_commons(v: NaiveInterpreter, mpropdef: MMethodDef, arguments: Array[Instance], f: Frame): nullable Instance
        do
                v.frames.unshift(f)
 
@@ -798,21 +964,27 @@ redef class AMethPropdef
                        v.call(superpd, arguments)
                end
 
+               # First, try intern
                if mpropdef.is_intern or mpropdef.is_extern then
                        var res = intern_call(v, mpropdef, arguments)
                        if res != v.error_instance then return res
                end
-
+               # Then, try extern
+               if mpropdef.is_extern then
+                       var res = call_extern(v, mpropdef, arguments, f)
+                       if res != v.error_instance then return res
+               end
+               # Else try block
                if n_block != null then
                        v.stmt(self.n_block)
                        return null
                end
 
+               # Fail if nothing succeed
                if mpropdef.is_intern then
                        fatal(v, "NOT YET IMPLEMENTED intern {mpropdef}")
                else if mpropdef.is_extern then
-                       var res = call_extern(v, mpropdef, arguments, f)
-                       if res != v.error_instance then return res
+                       fatal(v, "NOT YET IMPLEMENTED extern {mpropdef}")
                else
                        fatal(v, "NOT YET IMPLEMENTED <wat?> {mpropdef}")
                end
@@ -822,7 +994,6 @@ redef class AMethPropdef
        # Call this extern method
        protected fun call_extern(v: NaiveInterpreter, mpropdef: MMethodDef, arguments: Array[Instance], f: Frame): nullable Instance
        do
-               fatal(v, "NOT YET IMPLEMENTED extern {mpropdef}")
                return v.error_instance
        end
 
@@ -832,6 +1003,19 @@ redef class AMethPropdef
        do
                var pname = mpropdef.mproperty.name
                var cname = mpropdef.mclassdef.mclass.name
+
+               if pname == "call" and v.routine_types.has(cname) then
+                       var routine = args.shift
+                       assert routine isa CallrefInstance
+                       # Swap the receiver position with the original recv of the call form.
+                       args.unshift routine.recv
+                       var res = v.callsite(routine.callsite, args)
+                       # recover the old args state
+                       args.shift
+                       args.unshift routine
+                       return res
+               end
+
                if pname == "output" then
                        var recv = args.first
                        recv.val.output
@@ -850,7 +1034,7 @@ redef class AMethPropdef
                else if pname == "native_class_name" then
                        var recv = args.first
                        var txt = recv.mtype.to_s
-                       return v.native_string_instance(txt)
+                       return v.c_string_instance(txt)
                else if pname == "==" then
                        # == is correctly redefined for instances
                        return v.bool_instance(args[0] == args[1])
@@ -860,6 +1044,8 @@ redef class AMethPropdef
                        return v.bool_instance(args[0].mtype == args[1].mtype)
                else if pname == "is_same_instance" then
                        return v.bool_instance(args[0].eq_is(args[1]))
+               else if pname == "class_inheritance_metamodel_json" then
+                       return v.c_string_instance(v.mainmodule.flatten_mclass_hierarchy.to_thin_json)
                else if pname == "exit" then
                        exit(args[1].to_i)
                        abort
@@ -897,8 +1083,10 @@ redef class AMethPropdef
                                return v.bool_instance(recvval >= args[1].to_i)
                        else if pname == "<=>" then
                                return v.int_instance(recvval <=> args[1].to_i)
-                       else if pname == "ascii" then
-                               return v.char_instance(recvval.ascii)
+                       else if pname == "&" then
+                               return v.int_instance(recvval & args[1].to_i)
+                       else if pname == "|" then
+                               return v.int_instance(recvval | args[1].to_i)
                        else if pname == "to_f" then
                                return v.float_instance(recvval.to_f)
                        else if pname == "to_b" then
@@ -907,9 +1095,16 @@ redef class AMethPropdef
                                return v.int_instance(recvval << args[1].to_i)
                        else if pname == ">>" then
                                return v.int_instance(recvval >> args[1].to_i)
-                       else if pname == "rand" then
-                               var res = recvval.rand
-                               return v.int_instance(res)
+                       else if pname == "to_i8" then
+                               return v.int8_instance(recvval.to_i8)
+                       else if pname == "to_i16" then
+                               return v.int16_instance(recvval.to_i16)
+                       else if pname == "to_u16" then
+                               return v.uint16_instance(recvval.to_u16)
+                       else if pname == "to_i32" then
+                               return v.int32_instance(recvval.to_i32)
+                       else if pname == "to_u32" then
+                               return v.uint32_instance(recvval.to_u32)
                        end
                else if cname == "Byte" then
                        var recvval = args[0].to_b
@@ -937,6 +1132,10 @@ redef class AMethPropdef
                                return v.bool_instance(recvval >= args[1].to_b)
                        else if pname == "<=>" then
                                return v.int_instance(recvval <=> args[1].to_b)
+                       else if pname == "&" then
+                               return v.byte_instance(recvval & args[1].to_b)
+                       else if pname == "|" then
+                               return v.byte_instance(recvval | args[1].to_b)
                        else if pname == "to_f" then
                                return v.float_instance(recvval.to_f)
                        else if pname == "to_i" then
@@ -945,14 +1144,22 @@ redef class AMethPropdef
                                return v.byte_instance(recvval << args[1].to_i)
                        else if pname == ">>" then
                                return v.byte_instance(recvval >> args[1].to_i)
+                       else if pname == "to_i8" then
+                               return v.int8_instance(recvval.to_i8)
+                       else if pname == "to_i16" then
+                               return v.int16_instance(recvval.to_i16)
+                       else if pname == "to_u16" then
+                               return v.uint16_instance(recvval.to_u16)
+                       else if pname == "to_i32" then
+                               return v.int32_instance(recvval.to_i32)
+                       else if pname == "to_u32" then
+                               return v.uint32_instance(recvval.to_u32)
                        else if pname == "byte_to_s_len" then
                                return v.int_instance(recvval.to_s.length)
                        end
                else if cname == "Char" then
                        var recv = args[0].val.as(Char)
-                       if pname == "ascii" then
-                               return v.int_instance(recv.ascii)
-                       else if pname == "successor" then
+                       if pname == "successor" then
                                return v.char_instance(recv.successor(args[1].to_i))
                        else if pname == "predecessor" then
                                return v.char_instance(recv.predecessor(args[1].to_i))
@@ -993,6 +1200,16 @@ redef class AMethPropdef
                                return v.int_instance(recv.to_i)
                        else if pname == "to_b" then
                                return v.byte_instance(recv.to_b)
+                       else if pname == "to_i8" then
+                               return v.int8_instance(recv.to_i8)
+                       else if pname == "to_i16" then
+                               return v.int16_instance(recv.to_i16)
+                       else if pname == "to_u16" then
+                               return v.uint16_instance(recv.to_u16)
+                       else if pname == "to_i32" then
+                               return v.int32_instance(recv.to_i32)
+                       else if pname == "to_u32" then
+                               return v.uint32_instance(recv.to_u32)
                        else if pname == "cos" then
                                return v.float_instance(args[0].to_f.cos)
                        else if pname == "sin" then
@@ -1013,8 +1230,6 @@ redef class AMethPropdef
                                return v.float_instance(args[0].to_f.log)
                        else if pname == "pow" then
                                return v.float_instance(args[0].to_f.pow(args[1].to_f))
-                       else if pname == "rand" then
-                               return v.float_instance(args[0].to_f.rand)
                        else if pname == "abs" then
                                return v.float_instance(args[0].to_f.abs)
                        else if pname == "hypot_with" then
@@ -1026,21 +1241,21 @@ redef class AMethPropdef
                        else if pname == "round" then
                                return v.float_instance(args[0].to_f.round)
                        end
-               else if cname == "NativeString" then
+               else if cname == "CString" then
                        if pname == "new" then
-                               return v.native_string_instance_len(args[1].to_i)
+                               return v.c_string_instance_len(args[1].to_i)
                        end
-                       var recvval = args.first.val.as(NativeString)
+                       var recvval = args.first.val.as(CString)
                        if pname == "[]" then
                                var arg1 = args[1].to_i
-                               return v.byte_instance(recvval[arg1])
+                               return v.int_instance(recvval[arg1])
                        else if pname == "[]=" then
                                var arg1 = args[1].to_i
-                               recvval[arg1] = args[2].val.as(Byte)
+                               recvval[arg1] = args[2].val.as(Int)
                                return null
                        else if pname == "copy_to" then
-                               # sig= copy_to(dest: NativeString, length: Int, from: Int, to: Int)
-                               var destval = args[1].val.as(NativeString)
+                               # sig= copy_to(dest: CString, length: Int, from: Int, to: Int)
+                               var destval = args[1].val.as(CString)
                                var lenval = args[2].to_i
                                var fromval = args[3].to_i
                                var toval = args[4].to_i
@@ -1049,11 +1264,14 @@ redef class AMethPropdef
                        else if pname == "atoi" then
                                return v.int_instance(recvval.atoi)
                        else if pname == "fast_cstring" then
-                               var ns = recvval.to_s.substring_from(args[1].to_i)
-                               return v.native_string_instance(ns)
+                               return v.c_string_instance_fast_cstr(args[0].val.as(CString), args[1].to_i)
+                       else if pname == "fetch_4_chars" then
+                               return v.uint32_instance(args[0].val.as(CString).fetch_4_chars(args[1].to_i))
+                       else if pname == "fetch_4_hchars" then
+                               return v.uint32_instance(args[0].val.as(CString).fetch_4_hchars(args[1].to_i))
+                       else if pname == "utf8_length" then
+                               return v.int_instance(args[0].val.as(CString).utf8_length(args[1].to_i, args[2].to_i))
                        end
-               else if pname == "calloc_string" then
-                       return v.native_string_instance_len(args[1].to_i)
                else if cname == "NativeArray" then
                        if pname == "new" then
                                var val = new Array[Instance].filled_with(v.null_instance, args[1].to_i)
@@ -1073,16 +1291,276 @@ redef class AMethPropdef
                                recvval.copy_to(0, args[2].to_i, args[1].val.as(Array[Instance]), 0)
                                return null
                        end
+               else if cname == "Int8" then
+                       var recvval = args[0].to_i8
+                       if pname == "unary -" then
+                               return v.int8_instance(-recvval)
+                       else if pname == "unary +" then
+                               return args[0]
+                       else if pname == "+" then
+                               return v.int8_instance(recvval + args[1].to_i8)
+                       else if pname == "-" then
+                               return v.int8_instance(recvval - args[1].to_i8)
+                       else if pname == "*" then
+                               return v.int8_instance(recvval * args[1].to_i8)
+                       else if pname == "%" then
+                               return v.int8_instance(recvval % args[1].to_i8)
+                       else if pname == "/" then
+                               return v.int8_instance(recvval / args[1].to_i8)
+                       else if pname == "<" then
+                               return v.bool_instance(recvval < args[1].to_i8)
+                       else if pname == ">" then
+                               return v.bool_instance(recvval > args[1].to_i8)
+                       else if pname == "<=" then
+                               return v.bool_instance(recvval <= args[1].to_i8)
+                       else if pname == ">=" then
+                               return v.bool_instance(recvval >= args[1].to_i8)
+                       else if pname == "<=>" then
+                               return v.int_instance(recvval <=> args[1].to_i8)
+                       else if pname == "to_f" then
+                               return v.float_instance(recvval.to_f)
+                       else if pname == "to_i" then
+                               return v.int_instance(recvval.to_i)
+                       else if pname == "to_b" then
+                               return v.byte_instance(recvval.to_b)
+                       else if pname == "to_i16" then
+                               return v.int16_instance(recvval.to_i16)
+                       else if pname == "to_u16" then
+                               return v.uint16_instance(recvval.to_u16)
+                       else if pname == "to_i32" then
+                               return v.int32_instance(recvval.to_i32)
+                       else if pname == "to_u32" then
+                               return v.uint32_instance(recvval.to_u32)
+                       else if pname == "<<" then
+                               return v.int8_instance(recvval << (args[1].to_i))
+                       else if pname == ">>" then
+                               return v.int8_instance(recvval >> (args[1].to_i))
+                       else if pname == "&" then
+                               return v.int8_instance(recvval & args[1].to_i8)
+                       else if pname == "|" then
+                               return v.int8_instance(recvval | args[1].to_i8)
+                       else if pname == "^" then
+                               return v.int8_instance(recvval ^ args[1].to_i8)
+                       else if pname == "unary ~" then
+                               return v.int8_instance(~recvval)
+                       end
+               else if cname == "Int16" then
+                       var recvval = args[0].to_i16
+                       if pname == "unary -" then
+                               return v.int16_instance(-recvval)
+                       else if pname == "unary +" then
+                               return args[0]
+                       else if pname == "+" then
+                               return v.int16_instance(recvval + args[1].to_i16)
+                       else if pname == "-" then
+                               return v.int16_instance(recvval - args[1].to_i16)
+                       else if pname == "*" then
+                               return v.int16_instance(recvval * args[1].to_i16)
+                       else if pname == "%" then
+                               return v.int16_instance(recvval % args[1].to_i16)
+                       else if pname == "/" then
+                               return v.int16_instance(recvval / args[1].to_i16)
+                       else if pname == "<" then
+                               return v.bool_instance(recvval < args[1].to_i16)
+                       else if pname == ">" then
+                               return v.bool_instance(recvval > args[1].to_i16)
+                       else if pname == "<=" then
+                               return v.bool_instance(recvval <= args[1].to_i16)
+                       else if pname == ">=" then
+                               return v.bool_instance(recvval >= args[1].to_i16)
+                       else if pname == "<=>" then
+                               return v.int_instance(recvval <=> args[1].to_i16)
+                       else if pname == "to_f" then
+                               return v.float_instance(recvval.to_f)
+                       else if pname == "to_i" then
+                               return v.int_instance(recvval.to_i)
+                       else if pname == "to_b" then
+                               return v.byte_instance(recvval.to_b)
+                       else if pname == "to_i8" then
+                               return v.int8_instance(recvval.to_i8)
+                       else if pname == "to_u16" then
+                               return v.uint16_instance(recvval.to_u16)
+                       else if pname == "to_i32" then
+                               return v.int32_instance(recvval.to_i32)
+                       else if pname == "to_u32" then
+                               return v.uint32_instance(recvval.to_u32)
+                       else if pname == "<<" then
+                               return v.int16_instance(recvval << (args[1].to_i))
+                       else if pname == ">>" then
+                               return v.int16_instance(recvval >> (args[1].to_i))
+                       else if pname == "&" then
+                               return v.int16_instance(recvval & args[1].to_i16)
+                       else if pname == "|" then
+                               return v.int16_instance(recvval | args[1].to_i16)
+                       else if pname == "^" then
+                               return v.int16_instance(recvval ^ args[1].to_i16)
+                       else if pname == "unary ~" then
+                               return v.int16_instance(~recvval)
+                       end
+               else if cname == "UInt16" then
+                       var recvval = args[0].to_u16
+                       if pname == "unary -" then
+                               return v.uint16_instance(-recvval)
+                       else if pname == "unary +" then
+                               return args[0]
+                       else if pname == "+" then
+                               return v.uint16_instance(recvval + args[1].to_u16)
+                       else if pname == "-" then
+                               return v.uint16_instance(recvval - args[1].to_u16)
+                       else if pname == "*" then
+                               return v.uint16_instance(recvval * args[1].to_u16)
+                       else if pname == "%" then
+                               return v.uint16_instance(recvval % args[1].to_u16)
+                       else if pname == "/" then
+                               return v.uint16_instance(recvval / args[1].to_u16)
+                       else if pname == "<" then
+                               return v.bool_instance(recvval < args[1].to_u16)
+                       else if pname == ">" then
+                               return v.bool_instance(recvval > args[1].to_u16)
+                       else if pname == "<=" then
+                               return v.bool_instance(recvval <= args[1].to_u16)
+                       else if pname == ">=" then
+                               return v.bool_instance(recvval >= args[1].to_u16)
+                       else if pname == "<=>" then
+                               return v.int_instance(recvval <=> args[1].to_u16)
+                       else if pname == "to_f" then
+                               return v.float_instance(recvval.to_f)
+                       else if pname == "to_i" then
+                               return v.int_instance(recvval.to_i)
+                       else if pname == "to_b" then
+                               return v.byte_instance(recvval.to_b)
+                       else if pname == "to_i8" then
+                               return v.int8_instance(recvval.to_i8)
+                       else if pname == "to_i16" then
+                               return v.int16_instance(recvval.to_i16)
+                       else if pname == "to_i32" then
+                               return v.int32_instance(recvval.to_i32)
+                       else if pname == "to_u32" then
+                               return v.uint32_instance(recvval.to_u32)
+                       else if pname == "<<" then
+                               return v.uint16_instance(recvval << (args[1].to_i))
+                       else if pname == ">>" then
+                               return v.uint16_instance(recvval >> (args[1].to_i))
+                       else if pname == "&" then
+                               return v.uint16_instance(recvval & args[1].to_u16)
+                       else if pname == "|" then
+                               return v.uint16_instance(recvval | args[1].to_u16)
+                       else if pname == "^" then
+                               return v.uint16_instance(recvval ^ args[1].to_u16)
+                       else if pname == "unary ~" then
+                               return v.uint16_instance(~recvval)
+                       end
+               else if cname == "Int32" then
+                       var recvval = args[0].to_i32
+                       if pname == "unary -" then
+                               return v.int32_instance(-recvval)
+                       else if pname == "unary +" then
+                               return args[0]
+                       else if pname == "+" then
+                               return v.int32_instance(recvval + args[1].to_i32)
+                       else if pname == "-" then
+                               return v.int32_instance(recvval - args[1].to_i32)
+                       else if pname == "*" then
+                               return v.int32_instance(recvval * args[1].to_i32)
+                       else if pname == "%" then
+                               return v.int32_instance(recvval % args[1].to_i32)
+                       else if pname == "/" then
+                               return v.int32_instance(recvval / args[1].to_i32)
+                       else if pname == "<" then
+                               return v.bool_instance(recvval < args[1].to_i32)
+                       else if pname == ">" then
+                               return v.bool_instance(recvval > args[1].to_i32)
+                       else if pname == "<=" then
+                               return v.bool_instance(recvval <= args[1].to_i32)
+                       else if pname == ">=" then
+                               return v.bool_instance(recvval >= args[1].to_i32)
+                       else if pname == "<=>" then
+                               return v.int_instance(recvval <=> args[1].to_i32)
+                       else if pname == "to_f" then
+                               return v.float_instance(recvval.to_f)
+                       else if pname == "to_i" then
+                               return v.int_instance(recvval.to_i)
+                       else if pname == "to_b" then
+                               return v.byte_instance(recvval.to_b)
+                       else if pname == "to_i8" then
+                               return v.int8_instance(recvval.to_i8)
+                       else if pname == "to_i16" then
+                               return v.int16_instance(recvval.to_i16)
+                       else if pname == "to_u16" then
+                               return v.uint16_instance(recvval.to_u16)
+                       else if pname == "to_u32" then
+                               return v.uint32_instance(recvval.to_u32)
+                       else if pname == "<<" then
+                               return v.int32_instance(recvval << (args[1].to_i))
+                       else if pname == ">>" then
+                               return v.int32_instance(recvval >> (args[1].to_i))
+                       else if pname == "&" then
+                               return v.int32_instance(recvval & args[1].to_i32)
+                       else if pname == "|" then
+                               return v.int32_instance(recvval | args[1].to_i32)
+                       else if pname == "^" then
+                               return v.int32_instance(recvval ^ args[1].to_i32)
+                       else if pname == "unary ~" then
+                               return v.int32_instance(~recvval)
+                       end
+               else if cname == "UInt32" then
+                       var recvval = args[0].to_u32
+                       if pname == "unary -" then
+                               return v.uint32_instance(-recvval)
+                       else if pname == "unary +" then
+                               return args[0]
+                       else if pname == "+" then
+                               return v.uint32_instance(recvval + args[1].to_u32)
+                       else if pname == "-" then
+                               return v.uint32_instance(recvval - args[1].to_u32)
+                       else if pname == "*" then
+                               return v.uint32_instance(recvval * args[1].to_u32)
+                       else if pname == "%" then
+                               return v.uint32_instance(recvval % args[1].to_u32)
+                       else if pname == "/" then
+                               return v.uint32_instance(recvval / args[1].to_u32)
+                       else if pname == "<" then
+                               return v.bool_instance(recvval < args[1].to_u32)
+                       else if pname == ">" then
+                               return v.bool_instance(recvval > args[1].to_u32)
+                       else if pname == "<=" then
+                               return v.bool_instance(recvval <= args[1].to_u32)
+                       else if pname == ">=" then
+                               return v.bool_instance(recvval >= args[1].to_u32)
+                       else if pname == "<=>" then
+                               return v.int_instance(recvval <=> args[1].to_u32)
+                       else if pname == "to_f" then
+                               return v.float_instance(recvval.to_f)
+                       else if pname == "to_i" then
+                               return v.int_instance(recvval.to_i)
+                       else if pname == "to_b" then
+                               return v.byte_instance(recvval.to_b)
+                       else if pname == "to_i8" then
+                               return v.int8_instance(recvval.to_i8)
+                       else if pname == "to_i16" then
+                               return v.int16_instance(recvval.to_i16)
+                       else if pname == "to_u16" then
+                               return v.uint16_instance(recvval.to_u16)
+                       else if pname == "to_i32" then
+                               return v.int32_instance(recvval.to_i32)
+                       else if pname == "<<" then
+                               return v.uint32_instance(recvval << (args[1].to_i))
+                       else if pname == ">>" then
+                               return v.uint32_instance(recvval >> (args[1].to_i))
+                       else if pname == "&" then
+                               return v.uint32_instance(recvval & args[1].to_u32)
+                       else if pname == "|" then
+                               return v.uint32_instance(recvval | args[1].to_u32)
+                       else if pname == "^" then
+                               return v.uint32_instance(recvval ^ args[1].to_u32)
+                       else if pname == "unary ~" then
+                               return v.uint32_instance(~recvval)
+                       end
                else if pname == "native_argc" then
                        return v.int_instance(v.arguments.length)
                else if pname == "native_argv" then
                        var txt = v.arguments[args[1].to_i]
-                       return v.native_string_instance(txt)
-               else if pname == "native_argc" then
-                       return v.int_instance(v.arguments.length)
-               else if pname == "native_argv" then
-                       var txt = v.arguments[args[1].to_i]
-                       return v.native_string_instance(txt)
+                       return v.c_string_instance(txt)
                else if pname == "lexer_goto" then
                        return v.int_instance(lexer_goto(args[1].to_i, args[2].to_i))
                else if pname == "lexer_accept" then
@@ -1109,7 +1587,12 @@ redef class AAttrPropdef
                        return evaluate_expr(v, recv, f)
                else if mpropdef == mwritepropdef then
                        assert args.length == 2
-                       v.write_attribute(attr, recv, args[1])
+                       var arg = args[1]
+                       if is_optional and arg.is_null then
+                               var f = v.new_frame(self, mpropdef, args)
+                               arg = evaluate_expr(v, recv, f)
+                       end
+                       v.write_attribute(attr, recv, arg)
                        return null
                else
                        abort
@@ -1119,7 +1602,7 @@ redef class AAttrPropdef
        # Evaluate and set the default value of the attribute in `recv`
        private fun init_expr(v: NaiveInterpreter, recv: Instance)
        do
-               if is_lazy then return
+               if is_lazy or is_optional then return
                if has_value then
                        var f = v.new_frame(self, mreadpropdef.as(not null), [recv])
                        evaluate_expr(v, recv, f)
@@ -1147,10 +1630,9 @@ redef class AAttrPropdef
                        val = v.expr(nexpr)
                else if nblock != null then
                        v.stmt(nblock)
-                       assert v.returnmark == f
+                       assert v.escapemark == return_mark
                        val = v.escapevalue
-                       v.returnmark = null
-                       v.escapevalue = null
+                       v.escapemark = null
                else
                        abort
                end
@@ -1165,14 +1647,14 @@ end
 
 redef class AClassdef
        # Execute an implicit `mpropdef` associated with the current node.
-       private fun call(v: NaiveInterpreter, mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
+       private fun call(v: NaiveInterpreter, mpropdef: MMethodDef, arguments: Array[Instance]): nullable Instance
        do
                if mpropdef.mproperty.is_root_init then
-                       assert args.length == 1
+                       assert arguments.length == 1
                        if not mpropdef.is_intro then
                                # standard call-next-method
-                               var superpd = mpropdef.lookup_next_definition(v.mainmodule, args.first.mtype)
-                               v.call(superpd, args)
+                               var superpd = mpropdef.lookup_next_definition(v.mainmodule, arguments.first.mtype)
+                               v.call(superpd, arguments)
                        end
                        return null
                else
@@ -1290,24 +1772,13 @@ redef class AEscapeExpr
                        var i = v.expr(ne)
                        if i == null then return
                        v.escapevalue = i
+               else
+                       v.escapevalue = null
                end
                v.escapemark = self.escapemark
        end
 end
 
-redef class AReturnExpr
-       redef fun stmt(v)
-       do
-               var ne = self.n_expr
-               if ne != null then
-                       var i = v.expr(ne)
-                       if i == null then return
-                       v.escapevalue = i
-               end
-               v.returnmark = v.frame
-       end
-end
-
 redef class AAbortExpr
        redef fun stmt(v)
        do
@@ -1356,8 +1827,24 @@ end
 redef class ADoExpr
        redef fun stmt(v)
        do
-               v.stmt(self.n_block)
-               v.is_escape(self.break_mark) # Clear the break (if any)
+               # If this bloc has a catch, handle it with a do ... catch ... end
+               if self.n_catch != null then
+                       var frame = v.frame
+                       v.catch_count += 1
+                       do
+                               v.stmt(self.n_block)
+                               v.is_escape(self.break_mark) # Clear the break (if any)
+                               v.catch_count -= 1
+                       catch
+                               # Restore the current frame if needed
+                               while v.frame != frame do v.frames.shift
+                               v.catch_count -= 1
+                               v.stmt(self.n_catch)
+                       end
+               else
+                       v.stmt(self.n_block)
+                       v.is_escape(self.break_mark)
+               end
        end
 end
 
@@ -1391,37 +1878,47 @@ end
 redef class AForExpr
        redef fun stmt(v)
        do
-               var col = v.expr(self.n_expr)
-               if col == null then return
-               if col.mtype isa MNullType then fatal(v, "Receiver is null")
+               var iters = new Array[Instance]
+
+               for g in n_groups do
+                       var col = v.expr(g.n_expr)
+                       if col == null then return
+                       if col.is_null then fatal(v, "Receiver is null")
+
+                       var iter = v.callsite(g.method_iterator, [col]).as(not null)
+                       iters.add iter
+               end
 
-               #self.debug("col {col}")
-               var iter = v.callsite(method_iterator, [col]).as(not null)
-               #self.debug("iter {iter}")
                loop
-                       var isok = v.callsite(method_is_ok, [iter]).as(not null)
-                       if not isok.is_true then break
-                       if self.variables.length == 1 then
-                               var item = v.callsite(method_item, [iter]).as(not null)
-                               #self.debug("item {item}")
-                               v.write_variable(self.variables.first, item)
-                       else if self.variables.length == 2 then
-                               var key = v.callsite(method_key, [iter]).as(not null)
-                               v.write_variable(self.variables[0], key)
-                               var item = v.callsite(method_item, [iter]).as(not null)
-                               v.write_variable(self.variables[1], item)
-                       else
-                               abort
+                       for g in n_groups, iter in iters do
+                               var isok = v.callsite(g.method_is_ok, [iter]).as(not null)
+                               if not isok.is_true then break label
+                               if g.variables.length == 1 then
+                                       var item = v.callsite(g.method_item, [iter]).as(not null)
+                                       #self.debug("item {item}")
+                                       v.write_variable(g.variables.first, item)
+                               else if g.variables.length == 2 then
+                                       var key = v.callsite(g.method_key, [iter]).as(not null)
+                                       v.write_variable(g.variables[0], key)
+                                       var item = v.callsite(g.method_item, [iter]).as(not null)
+                                       v.write_variable(g.variables[1], item)
+                               else
+                                       abort
+                               end
                        end
                        v.stmt(self.n_block)
                        if v.is_escape(self.break_mark) then break
                        v.is_escape(self.continue_mark) # Clear the break
                        if v.is_escaping then break
-                       v.callsite(method_next, [iter])
-               end
-               var method_finish = self.method_finish
-               if method_finish != null then
-                       v.callsite(method_finish, [iter])
+                       for g in n_groups, iter in iters do
+                               v.callsite(g.method_next, [iter])
+                       end
+               end label
+               for g in n_groups, iter in iters do
+                       var method_finish = g.method_finish
+                       if method_finish != null then
+                               v.callsite(method_finish, [iter])
+                       end
                end
        end
 end
@@ -1435,7 +1932,13 @@ redef class AWithExpr
                v.callsite(method_start, [expr])
                v.stmt(self.n_block)
                v.is_escape(self.break_mark) # Clear the break
+
+               # Execute the finally without an escape
+               var old_mark = v.escapemark
+               v.escapemark = null
                v.callsite(method_finish, [expr])
+               # Restore the escape unless another escape was provided
+               if v.escapemark == null then v.escapemark = old_mark
        end
 end
 
@@ -1447,6 +1950,22 @@ redef class AAssertExpr
                if not cond.is_true then
                        v.stmt(self.n_else)
                        if v.is_escaping then return
+
+                       # Explain assert if it fails
+                       var explain_assert_str = explain_assert_str
+                       if explain_assert_str != null then
+                               var i = v.expr(explain_assert_str)
+                               if i isa MutableInstance then
+                                       var res = v.send(v.force_get_primitive_method("to_cstring", i.mtype), [i])
+                                       if res != null then
+                                               var val = res.val
+                                               if val != null then
+                                                       print_error "Runtime assert: {val.to_s}"
+                                               end
+                                       end
+                               end
+                       end
+
                        var nid = self.n_id
                        if nid != null then
                                fatal(v, "Assert '{nid.text}' failed")
@@ -1512,6 +2031,11 @@ redef class AIntegerExpr
        do
                if value isa Int then return v.int_instance(value.as(Int))
                if value isa Byte then return v.byte_instance(value.as(Byte))
+               if value isa Int8 then return v.int8_instance(value.as(Int8))
+               if value isa Int16 then return v.int16_instance(value.as(Int16))
+               if value isa UInt16 then return v.uint16_instance(value.as(UInt16))
+               if value isa Int32 then return v.int32_instance(value.as(Int32))
+               if value isa UInt32 then return v.uint32_instance(value.as(UInt32))
                return null
        end
 end
@@ -1526,6 +2050,9 @@ end
 redef class ACharExpr
        redef fun expr(v)
        do
+               if is_code_point then
+                       return v.int_instance(self.value.as(not null).code_point)
+               end
                return v.char_instance(self.value.as(not null))
        end
 end
@@ -1552,11 +2079,71 @@ redef class AArrayExpr
        end
 end
 
+redef class AugmentedStringFormExpr
+       # Factorize the making of a `Regex` object from a literal prefixed string
+       fun make_re(v: NaiveInterpreter, rs: Instance): nullable Instance do
+               var tore = to_re
+               assert tore != null
+               var res = v.callsite(tore, [rs])
+               if res == null then
+                       print "Cannot call property `to_re` on {self}"
+                       abort
+               end
+               for j in suffix.chars do
+                       if j == 'i' then
+                               var prop = ignore_case
+                               assert prop != null
+                               v.callsite(prop, [res, v.bool_instance(true)])
+                               continue
+                       end
+                       if j == 'm' then
+                               var prop = newline
+                               assert prop != null
+                               v.callsite(prop, [res, v.bool_instance(true)])
+                               continue
+                       end
+                       if j == 'b' then
+                               var prop = extended
+                               assert prop != null
+                               v.callsite(prop, [res, v.bool_instance(false)])
+                               continue
+                       end
+                       # Should not happen, this needs to be updated
+                       # along with the addition of new suffixes
+                       abort
+               end
+               return res
+       end
+end
+
 redef class AStringFormExpr
-       redef fun expr(v)
-       do
-               var txt = self.value.as(not null)
-               return v.string_instance(txt)
+       redef fun expr(v) do return v.string_instance(value)
+end
+
+redef class AStringExpr
+       redef fun expr(v) do
+               var s = v.string_instance(value)
+               if is_string then return s
+               if is_bytestring then
+                       var ns = v.c_string_instance_from_ns(bytes.items, bytes.length)
+                       var ln = v.int_instance(bytes.length)
+                       var prop = to_bytes_with_copy
+                       assert prop != null
+                       var res = v.callsite(prop, [ns, ln])
+                       if res == null then
+                               print "Cannot call property `to_bytes` on {self}"
+                               abort
+                       end
+                       s = res
+               else if is_re then
+                       var res = make_re(v, s)
+                       assert res != null
+                       s = res
+               else
+                       print "Unimplemented prefix or suffix for {self}"
+                       abort
+               end
+               return s
        end
 end
 
@@ -1572,6 +2159,7 @@ redef class ASuperstringExpr
                var i = v.array_instance(array, v.mainmodule.object_type)
                var res = v.send(v.force_get_primitive_method("plain_to_s", i.mtype), [i])
                assert res != null
+               if is_re then res = make_re(v, res)
                return res
        end
 end
@@ -1656,7 +2244,7 @@ redef class AAsNotnullExpr
        do
                var i = v.expr(self.n_expr)
                if i == null then return null
-               if i.mtype isa MNullType then
+               if i.is_null then
                        fatal(v, "Cast failed")
                end
                return i
@@ -1689,14 +2277,34 @@ redef class ASendExpr
        do
                var recv = v.expr(self.n_expr)
                if recv == null then return null
+
+               # Safe call shortcut if recv is null
+               if is_safe and recv.is_null then
+                       return recv
+               end
+
                var args = v.varargize(callsite.mpropdef, callsite.signaturemap, recv, self.raw_arguments)
                if args == null then return null
-
                var res = v.callsite(callsite, args)
                return res
        end
 end
 
+redef class ACallrefExpr
+       redef fun expr(v)
+       do
+               var recv = v.expr(self.n_expr)
+               if recv == null then return null
+               var mtype = self.mtype
+               assert mtype != null
+               # In case we are in generic class where formal parameter can not
+               # be resolved.
+               var mtype2 = v.unanchor_type(mtype)
+               var inst = new CallrefInstance(mtype2, recv, callsite.as(not null))
+               return inst
+       end
+end
+
 redef class ASendReassignFormExpr
        redef fun stmt(v)
        do
@@ -1785,7 +2393,7 @@ redef class AAttrExpr
        do
                var recv = v.expr(self.n_expr)
                if recv == null then return null
-               if recv.mtype isa MNullType then fatal(v, "Receiver is null")
+               if recv.is_null then fatal(v, "Receiver is null")
                var mproperty = self.mproperty.as(not null)
                return v.read_attribute(mproperty, recv)
        end
@@ -1796,7 +2404,7 @@ redef class AAttrAssignExpr
        do
                var recv = v.expr(self.n_expr)
                if recv == null then return
-               if recv.mtype isa MNullType then fatal(v, "Receiver is null")
+               if recv.is_null then fatal(v, "Receiver is null")
                var i = v.expr(self.n_value)
                if i == null then return
                var mproperty = self.mproperty.as(not null)
@@ -1809,7 +2417,7 @@ redef class AAttrReassignExpr
        do
                var recv = v.expr(self.n_expr)
                if recv == null then return
-               if recv.mtype isa MNullType then fatal(v, "Receiver is null")
+               if recv.is_null then fatal(v, "Receiver is null")
                var value = v.expr(self.n_value)
                if value == null then return
                var mproperty = self.mproperty.as(not null)
@@ -1825,7 +2433,7 @@ redef class AIssetAttrExpr
        do
                var recv = v.expr(self.n_expr)
                if recv == null then return null
-               if recv.mtype isa MNullType then fatal(v, "Receiver is null")
+               if recv.is_null then fatal(v, "Receiver is null")
                var mproperty = self.mproperty.as(not null)
                return v.bool_instance(v.isset_attribute(mproperty, recv))
        end
@@ -1838,6 +2446,13 @@ redef class AVarargExpr
        end
 end
 
+redef class ASafeExpr
+       redef fun expr(v)
+       do
+               return v.expr(self.n_expr)
+       end
+end
+
 redef class ANamedargExpr
        redef fun expr(v)
        do