src: create groups for related things

[nit.git] / src / compiler / global_compiler.nit

# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2012 Jean Privat <jean@pryen.org>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Global compilation of a Nit program
#
# Techniques used are:
#   * heterogeneous generics
#   * customization
#   * switch dispatch
#   * inlining
module global_compiler

import abstract_compiler
import rapid_type_analysis

redef class ToolContext
        # option --global
        var opt_global = new OptionBool("Use global compilation", "--global")

        var global_compiler_phase = new GlobalCompilerPhase(self, null)

        redef init do
                super
                option_context.add_option(opt_global)
        end
end

class GlobalCompilerPhase
        super Phase
        redef fun process_mainmodule(mainmodule, given_mmodules) do
                if not toolcontext.opt_global.value then return

                var modelbuilder = toolcontext.modelbuilder
                var analysis = modelbuilder.do_rapid_type_analysis(mainmodule)
                modelbuilder.run_global_compiler(mainmodule, analysis)
        end
end

redef class ModelBuilder
        # Entry point to performs a global compilation on the AST of a complete program.
        # `mainmodule` is the main module of the program
        # `runtime_type_analysis` is a already computer type analysis.
        fun run_global_compiler(mainmodule: MModule, runtime_type_analysis: RapidTypeAnalysis)
        do
                var time0 = get_time
                self.toolcontext.info("*** GENERATING C ***", 1)

                var compiler = new GlobalCompiler(mainmodule, self, runtime_type_analysis)
                compiler.compile_header

                for t in runtime_type_analysis.live_types do
                        compiler.declare_runtimeclass(t)
                end

                compiler.compile_class_names

                # Init instance code (allocate and init-arguments)
                for t in runtime_type_analysis.live_types do
                        if t.ctype == "val*" then
                                compiler.generate_init_instance(t)
                        else
                                compiler.generate_box_instance(t)
                        end
                end

                # The main function of the C
                compiler.compile_nitni_global_ref_functions
                compiler.compile_main_function

                # Compile until all runtime_functions are visited
                while not compiler.todos.is_empty do
                        var m = compiler.todos.shift
                        self.toolcontext.info("Compile {m} ({compiler.seen.length-compiler.todos.length}/{compiler.seen.length})", 3)
                        m.compile_to_c(compiler)
                end
                self.toolcontext.info("Total methods to compile to C: {compiler.seen.length}", 2)

                compiler.display_stats

                var time1 = get_time
                self.toolcontext.info("*** END GENERATING C: {time1-time0} ***", 2)
                write_and_make(compiler)
        end
end

# Compiler that use global compilation and perform hard optimisations like:
#   * customization
#   * switch dispatch
#   * inlining
class GlobalCompiler
        super AbstractCompiler

        redef type VISITOR: GlobalCompilerVisitor

        # The result of the RTA (used to know live types and methods)
        var runtime_type_analysis: RapidTypeAnalysis

        init(mainmodule: MModule, modelbuilder: ModelBuilder, runtime_type_analysis: RapidTypeAnalysis)
        do
                super(mainmodule, modelbuilder)
                var file = new_file("{mainmodule.name}.nitgg")
                self.header = new CodeWriter(file)
                self.runtime_type_analysis = runtime_type_analysis
                self.live_primitive_types = new Array[MClassType]
                for t in runtime_type_analysis.live_types do
                        if t.ctype != "val*" then
                                self.live_primitive_types.add(t)
                        end
                end
        end

        # Compile class names (for the class_name and output_class_name methods)
        protected fun compile_class_names do
                var v = new_visitor
                self.header.add_decl("extern const char *class_names[];")
                v.add("const char *class_names[] = \{")
                for t in self.runtime_type_analysis.live_types do
                        v.add("\"{t}\", /* {self.classid(t)} */")
                end
                v.add("\};")
        end

        # Return the C symbol associated to a live type runtime
        # REQUIRE: self.runtime_type_analysis.live_types.has(mtype)
        fun classid(mtype: MClassType): String
        do
                if self.classids.has_key(mtype) then
                        return self.classids[mtype]
                end
                print "No classid for {mtype}"
                abort
        end

        # Cache for classid
        protected var classids: HashMap[MClassType, String] = new HashMap[MClassType, String]

        # Declaration of structures the live Nit types
        # Each live type is generated as an independent C `struct` type.
        # They only share a common first field `classid` used to implement the polymorphism.
        # Usualy, all C variables that refers to a Nit object are typed on the abstract struct `val` that contains only the `classid` field.
        redef fun compile_header_structs do
                self.header.add_decl("typedef struct \{int classid;\} val; /* general C type representing a Nit instance. */")
        end

        # Subset of runtime_type_analysis.live_types that contains only primitive types
        # Used to implement the equal test
        var live_primitive_types: Array[MClassType]

        # Add a new todo task
        fun todo(m: AbstractRuntimeFunction)
        do
                if seen.has(m) then return
                todos.add(m)
                seen.add(m)
        end

        # runtime_functions that need to be compiled
        private var todos: List[AbstractRuntimeFunction] = new List[AbstractRuntimeFunction]

        # runtime_functions already seen (todo or done)
        private var seen: HashSet[AbstractRuntimeFunction] = new HashSet[AbstractRuntimeFunction]

        # Declare C structures and identifiers for a runtime class
        fun declare_runtimeclass(mtype: MClassType)
        do
                var v = self.header
                assert self.runtime_type_analysis.live_types.has(mtype)
                v.add_decl("/* runtime class {mtype} */")
                var idnum = classids.length
                var idname = "ID_" + mtype.c_name
                self.classids[mtype] = idname
                v.add_decl("#define {idname} {idnum} /* {mtype} */")

                v.add_decl("struct {mtype.c_name} \{")
                v.add_decl("int classid; /* must be {idname} */")

                if mtype.mclass.name == "NativeArray" then
                        # NativeArrays are just a instance header followed by an array of values
                        v.add_decl("int length;")
                        v.add_decl("{mtype.arguments.first.ctype} values[1];")
                end

                if mtype.ctype != "val*" then
                        # Is the Nit type is native then the struct is a box with two fields:
                        # * the `classid` to be polymorph
                        # * the `value` that contains the native value.
                        v.add_decl("{mtype.ctype} value;")
                end

                # Collect all attributes and associate them a field in the structure.
                # Note: we do not try to optimize the order and helps CC to optimize the client code.
                for cd in mtype.collect_mclassdefs(self.mainmodule) do
                        for p in cd.intro_mproperties do
                                if not p isa MAttribute then continue
                                var t = p.intro.static_mtype.as(not null)
                                t = t.anchor_to(self.mainmodule, mtype)
                                v.add_decl("{t.ctype} {p.intro.c_name}; /* {p}: {t} */")
                        end
                end
                v.add_decl("\};")
        end

        # Generate the init-instance of a live type (allocate + init-instance)
        fun generate_init_instance(mtype: MClassType)
        do
                assert self.runtime_type_analysis.live_types.has(mtype)
                assert mtype.ctype == "val*"
                var v = self.new_visitor

                var is_native_array = mtype.mclass.name == "NativeArray"

                var sig
                if is_native_array then
                        sig = "int length"
                else
                        sig = "void"
                end

                self.header.add_decl("{mtype.ctype} NEW_{mtype.c_name}({sig});")
                v.add_decl("/* allocate {mtype} */")
                v.add_decl("{mtype.ctype} NEW_{mtype.c_name}({sig}) \{")
                var res = v.new_var(mtype)
                res.is_exact = true
                if is_native_array then
                        var mtype_elt = mtype.arguments.first
                        v.add("{res} = nit_alloc(sizeof(struct {mtype.c_name}) + length*sizeof({mtype_elt.ctype}));")
                        v.add("((struct {mtype.c_name}*){res})->length = length;")
                else
                        v.add("{res} = nit_alloc(sizeof(struct {mtype.c_name}));")
                end
                v.add("{res}->classid = {self.classid(mtype)};")

                self.generate_init_attr(v, res, mtype)
                v.set_finalizer res
                v.add("return {res};")
                v.add("\}")
        end

        fun generate_box_instance(mtype: MClassType)
        do
                assert self.runtime_type_analysis.live_types.has(mtype)
                assert mtype.ctype != "val*"
                var v = self.new_visitor

                self.header.add_decl("val* BOX_{mtype.c_name}({mtype.ctype});")
                v.add_decl("/* allocate {mtype} */")
                v.add_decl("val* BOX_{mtype.c_name}({mtype.ctype} value) \{")
                v.add("struct {mtype.c_name}*res = nit_alloc(sizeof(struct {mtype.c_name}));")
                v.add("res->classid = {self.classid(mtype)};")
                v.add("res->value = value;")
                v.add("return (val*)res;")
                v.add("\}")
        end

        redef fun new_visitor do return new GlobalCompilerVisitor(self)

        private var collect_types_cache: HashMap[MType, Array[MClassType]] = new HashMap[MType, Array[MClassType]]

        redef fun compile_nitni_structs
        do
                self.header.add_decl """
struct nitni_instance \{
        struct nitni_instance *next,
                *prev; /* adjacent global references in global list */
        int count; /* number of time this global reference has been marked */
        val *value;
\};"""
                super
        end
end

# A visitor on the AST of property definition that generate the C code.
# Because of inlining, a visitor can visit more than one property.
class GlobalCompilerVisitor
        super AbstractCompilerVisitor

        redef type COMPILER: GlobalCompiler

        redef fun autobox(value, mtype)
        do
                if value.mtype == mtype then
                        return value
                else if value.mtype.ctype == "val*" and mtype.ctype == "val*" then
                        return value
                else if value.mtype.ctype == "val*" then
                        return self.new_expr("((struct {mtype.c_name}*){value})->value; /* autounbox from {value.mtype} to {mtype} */", mtype)
                else if mtype.ctype == "val*" then
                        var valtype = value.mtype.as(MClassType)
                        var res = self.new_var(mtype)
                        if not compiler.runtime_type_analysis.live_types.has(valtype) then
                                self.add("/*no autobox from {value.mtype} to {mtype}: {value.mtype} is not live! */")
                                self.add("PRINT_ERROR(\"Dead code executed!\\n\"); show_backtrace(1);")
                                return res
                        end
                        self.add("{res} = BOX_{valtype.c_name}({value}); /* autobox from {value.mtype} to {mtype} */")
                        return res
                else if value.mtype.ctype == "void*" and mtype.ctype == "void*" then
                        return value
                else
                        # Bad things will appen!
                        var res = self.new_var(mtype)
                        self.add("/* {res} left unintialized (cannot convert {value.mtype} to {mtype}) */")
                        self.add("PRINT_ERROR(\"Cast error: Cannot cast %s to %s.\\n\", \"{value.mtype}\", \"{mtype}\"); show_backtrace(1);")
                        return res
                end
        end

        # The runtime types that are acceptable for a given receiver.
        fun collect_types(recv: RuntimeVariable): Array[MClassType]
        do
                var mtype = recv.mcasttype
                if recv.is_exact then
                        assert mtype isa MClassType
                        assert self.compiler.runtime_type_analysis.live_types.has(mtype)
                        var types = [mtype]
                        return types
                end
                var cache = self.compiler.collect_types_cache
                if cache.has_key(mtype) then
                        return cache[mtype]
                end
                var types = new Array[MClassType]
                var mainmodule = self.compiler.mainmodule
                for t in self.compiler.runtime_type_analysis.live_types do
                        if not t.is_subtype(mainmodule, null, mtype) then continue
                        types.add(t)
                end
                cache[mtype] = types
                return types
        end

        redef fun native_array_def(pname, ret_type, arguments)
        do
                var elttype = arguments.first.mtype
                var recv = "((struct {arguments[0].mcasttype.c_name}*){arguments[0]})->values"
                if pname == "[]" then
                        self.ret(self.new_expr("{recv}[{arguments[1]}]", ret_type.as(not null)))
                        return
                else if pname == "[]=" then
                        self.add("{recv}[{arguments[1]}]={arguments[2]};")
                        return
                else if pname == "length" then
                        self.ret(self.new_expr("((struct {arguments[0].mcasttype.c_name}*){arguments[0]})->length", ret_type.as(not null)))
                        return
                else if pname == "copy_to" then
                        var recv1 = "((struct {arguments[1].mcasttype.c_name}*){arguments[1]})->values"
                        self.add("memmove({recv1},{recv},{arguments[2]}*sizeof({elttype.ctype}));")
                        return
                end
        end

        redef fun native_array_instance(elttype: MType, length: RuntimeVariable): RuntimeVariable
        do
                var ret_type = self.get_class("NativeArray").get_mtype([elttype])
                return self.new_expr("NEW_{ret_type.c_name}({length})", ret_type)
        end

        redef fun calloc_array(ret_type, arguments)
        do
                self.ret(self.new_expr("NEW_{ret_type.c_name}({arguments[1]})", ret_type))
        end

        redef fun send(m, args)
        do
                var types = self.collect_types(args.first)

                var res: nullable RuntimeVariable
                var ret = m.intro.msignature.return_mtype
                if m.is_new then
                        ret = args.first.mtype
                        res = self.new_var(ret)
                else if ret == null then
                        res = null
                else
                        ret = self.resolve_for(ret, args.first)
                        res = self.new_var(ret)
                end

                self.add("/* send {m} on {args.first.inspect} */")
                if args.first.mtype.ctype != "val*" then
                        var mclasstype = args.first.mtype.as(MClassType)
                        if not self.compiler.runtime_type_analysis.live_types.has(mclasstype) then
                                self.add("/* skip, no method {m} */")
                                return res
                        end
                        var propdef = m.lookup_first_definition(self.compiler.mainmodule, mclasstype)
                        var res2 = self.call(propdef, mclasstype, args)
                        if res != null then self.assign(res, res2.as(not null))
                        return res
                end
                var consider_null = not self.compiler.modelbuilder.toolcontext.opt_no_check_null.value or m.name == "==" or m.name == "!="
                if args.first.mcasttype isa MNullableType or args.first.mcasttype isa MNullType and consider_null then
                        # The reciever is potentially null, so we have to 3 cases: ==, != or NullPointerException
                        self.add("if ({args.first} == NULL) \{ /* Special null case */")
                        if m.name == "==" then
                                assert res != null
                                if args[1].mcasttype isa MNullableType then
                                        self.add("{res} = ({args[1]} == NULL);")
                                else if args[1].mcasttype isa MNullType then
                                        self.add("{res} = 1; /* is null */")
                                else
                                        self.add("{res} = 0; /* {args[1].inspect} cannot be null */")
                                end
                        else if m.name == "!=" then
                                assert res != null
                                if args[1].mcasttype isa MNullableType then
                                        self.add("{res} = ({args[1]} != NULL);")
                                else if args[1].mcasttype isa MNullType then
                                        self.add("{res} = 0; /* is null */")
                                else
                                        self.add("{res} = 1; /* {args[1].inspect} cannot be null */")
                                end
                        else
                                self.add_abort("Receiver is null")
                        end
                        self.add "\} else"
                end
                if types.is_empty then
                        self.add("\{")
                        self.add("/*BUG: no live types for {args.first.inspect} . {m}*/")
                        self.bugtype(args.first)
                        self.add("\}")
                        return res
                end

                self.add("switch({args.first}->classid) \{")
                var last = types.last
                var defaultpropdef: nullable MMethodDef = null
                for t in types do
                        var propdef = m.lookup_first_definition(self.compiler.mainmodule, t)
                        if propdef.mclassdef.mclass.name == "Object" and t.ctype == "val*" then
                                defaultpropdef = propdef
                                continue
                        end
                        if not self.compiler.hardening and t == last and defaultpropdef == null then
                                self.add("default: /* test {t} */")
                        else
                                self.add("case {self.compiler.classid(t)}: /* test {t} */")
                        end
                        var res2 = self.call(propdef, t, args)
                        if res != null then self.assign(res, res2.as(not null))
                        self.add "break;"
                end
                if defaultpropdef != null then
                        self.add("default: /* default is Object */")
                        var res2 = self.call(defaultpropdef, defaultpropdef.mclassdef.bound_mtype, args)
                        if res != null then self.assign(res, res2.as(not null))
                else if self.compiler.hardening then
                        self.add("default: /* bug */")
                        self.bugtype(args.first)
                end
                self.add("\}")
                return res
        end

        fun check_valid_reciever(recvtype: MClassType)
        do
                if self.compiler.runtime_type_analysis.live_types.has(recvtype) or recvtype.mclass.name == "Object" then return
                print "{recvtype} is not a live type"
                abort
        end

        # Subpart of old call function
        #
        # Checks if the type of the receiver is valid and corrects it if necessary
        private fun get_recvtype(m: MMethodDef, recvtype: MClassType, args: Array[RuntimeVariable]): MClassType
        do
                check_valid_reciever(recvtype)
                #debug("call {m} on {recvtype} on {args.first}:{args.first.mtype}")
                if m.mproperty.is_toplevel then
                        # Do not customize top-level methods
                        recvtype = m.mclassdef.bound_mtype
                end
                return recvtype
        end

        # Subpart of old call function
        # Gets the receiver boxed and casted if necessary
        private fun get_recv(recvtype: MClassType, args: Array[RuntimeVariable]): RuntimeVariable
        do
                return self.autoadapt(self.autobox(args.first, recvtype), recvtype)
        end

        # Finalizes a call to a method ´m´ on type ´recvtype´ with arguments ´args´
        private fun finalize_call(m: MMethodDef, recvtype: MClassType, args: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                assert args.length == m.msignature.arity + 1 else debug("Invalid arity for {m}. {args.length} arguments given.")

                var rm = new CustomizedRuntimeFunction(m, recvtype)
                return rm.call(self, args)
        end

        redef fun call(m, recvtype, args)
        do
                var recv_type = get_recvtype(m, recvtype, args)
                var recv = get_recv(recv_type, args)
                var new_args = args.to_a
                self.varargize(m, m.msignature.as(not null), new_args)
                new_args.first = recv
                return finalize_call(m, recv_type, new_args)
        end

        # Does a call without encapsulating varargs into an array
        # Avoids multiple encapsulation when calling a super in a variadic function
        fun call_without_varargize(m: MMethodDef, recvtype: MClassType, args: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                var recv_type = get_recvtype(m, recvtype, args)
                var recv = get_recv(recv_type, args)
                var new_args = args.to_a
                new_args.first = recv
                return finalize_call(m, recv_type, new_args)
        end

        redef fun supercall(m: MMethodDef, recvtype: MClassType, args: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                var types = self.collect_types(args.first)

                var res: nullable RuntimeVariable
                var ret = m.mproperty.intro.msignature.return_mtype
                if ret == null then
                        res = null
                else
                        ret = self.resolve_for(ret, args.first)
                        res = self.new_var(ret)
                end

                self.add("/* super {m} on {args.first.inspect} */")
                if args.first.mtype.ctype != "val*" then
                        var mclasstype = args.first.mtype.as(MClassType)
                        if not self.compiler.runtime_type_analysis.live_types.has(mclasstype) then
                                self.add("/* skip, no method {m} */")
                                return res
                        end
                        var propdef = m.lookup_next_definition(self.compiler.mainmodule, mclasstype)
                        var res2 = self.call_without_varargize(propdef, mclasstype, args)
                        if res != null then self.assign(res, res2.as(not null))
                        return res
                end

                if types.is_empty then
                        self.add("\{")
                        self.add("/*BUG: no live types for {args.first.inspect} . {m}*/")
                        self.bugtype(args.first)
                        self.add("\}")
                        return res
                end

                self.add("switch({args.first}->classid) \{")
                var last = types.last
                for t in types do
                        var propdef = m.lookup_next_definition(self.compiler.mainmodule, t)
                        if not self.compiler.hardening and t == last then
                                self.add("default: /* test {t} */")
                        else
                                self.add("case {self.compiler.classid(t)}: /* test {t} */")
                        end
                        var res2 = self.call_without_varargize(propdef, t, args)
                        if res != null then self.assign(res, res2.as(not null))
                        self.add "break;"
                end
                if self.compiler.hardening then
                        self.add("default: /* bug */")
                        self.bugtype(args.first)
                end
                self.add("\}")
                return res
        end

        redef fun adapt_signature(m, args)
        do
                var recv = args.first
                for i in [0..m.msignature.arity[ do
                        var t = m.msignature.mparameters[i].mtype
                        if i == m.msignature.vararg_rank then
                                t = args[i+1].mtype
                        end
                        t = self.resolve_for(t, recv)
                        args[i+1] = self.autobox(args[i+1], t)
                end
        end

        # FIXME: this is currently buggy since recv is not exact
        redef fun vararg_instance(mpropdef, recv, varargs, elttype)
        do
                elttype = self.resolve_for(elttype, recv)
                return self.array_instance(varargs, elttype)
        end

        fun bugtype(recv: RuntimeVariable)
        do
                if recv.mtype.ctype != "val*" then return
                self.add("PRINT_ERROR(\"BTD BUG: Dynamic type is %s, static type is %s\\n\", class_names[{recv}->classid], \"{recv.mcasttype}\");")
                self.add("show_backtrace(1);")
        end

        redef fun isset_attribute(a, recv)
        do
                check_recv_notnull(recv)

                var types = self.collect_types(recv)
                var res = self.new_var(bool_type)

                if types.is_empty then
                        self.add("/*BUG: no live types for {recv.inspect} . {a}*/")
                        self.bugtype(recv)
                        return res
                end
                self.add("/* isset {a} on {recv.inspect} */")
                self.add("switch({recv}->classid) \{")
                var last = types.last
                for t in types do
                        if not self.compiler.hardening and t == last then
                                self.add("default: /*{self.compiler.classid(t)}*/")
                        else
                                self.add("case {self.compiler.classid(t)}:")
                        end
                        var recv2 = self.autoadapt(recv, t)
                        var ta = a.intro.static_mtype.as(not null)
                        ta = self.resolve_for(ta, recv2)
                        var attr = self.new_expr("((struct {t.c_name}*){recv})->{a.intro.c_name}", ta)
                        if not ta isa MNullableType then
                                if ta.ctype == "val*" then
                                        self.add("{res} = ({attr} != NULL);")
                                else
                                        self.add("{res} = 1; /*NOTYET isset on primitive attributes*/")
                                end
                        end
                        self.add("break;")
                end
                if self.compiler.hardening then
                        self.add("default: /* Bug */")
                        self.bugtype(recv)
                end
                self.add("\}")

                return res
        end

        redef fun read_attribute(a, recv)
        do
                check_recv_notnull(recv)

                var types = self.collect_types(recv)

                var ret = a.intro.static_mtype.as(not null)
                ret = self.resolve_for(ret, recv)
                var res = self.new_var(ret)

                if types.is_empty then
                        self.add("/*BUG: no live types for {recv.inspect} . {a}*/")
                        self.bugtype(recv)
                        return res
                end
                self.add("/* read {a} on {recv.inspect} */")
                self.add("switch({recv}->classid) \{")
                var last = types.last
                for t in types do
                        if not self.compiler.hardening and t == last then
                                self.add("default: /*{self.compiler.classid(t)}*/")
                        else
                                self.add("case {self.compiler.classid(t)}:")
                        end
                        var recv2 = self.autoadapt(recv, t)
                        var ta = a.intro.static_mtype.as(not null)
                        ta = self.resolve_for(ta, recv2)
                        var res2 = self.new_expr("((struct {t.c_name}*){recv})->{a.intro.c_name}", ta)
                        if not ta isa MNullableType and not self.compiler.modelbuilder.toolcontext.opt_no_check_attr_isset.value then
                                if ta.ctype == "val*" then
                                        self.add("if ({res2} == NULL) \{")
                                        self.add_abort("Uninitialized attribute {a.name}")
                                        self.add("\}")
                                else
                                        self.add("/*NOTYET isset on primitive attributes*/")
                                end
                        end
                        self.assign(res, res2)
                        self.add("break;")
                end
                if self.compiler.hardening then
                        self.add("default: /* Bug */")
                        self.bugtype(recv)
                end
                self.add("\}")

                return res
        end

        redef fun write_attribute(a, recv, value)
        do
                check_recv_notnull(recv)

                var types = self.collect_types(recv)

                if types.is_empty then
                        self.add("/*BUG: no live types for {recv.inspect} . {a}*/")
                        self.bugtype(recv)
                        return
                end
                self.add("/* write {a} on {recv.inspect} */")
                self.add("switch({recv}->classid) \{")
                var last = types.last
                for t in types do
                        if not self.compiler.hardening and t == last then
                                self.add("default: /*{self.compiler.classid(t)}*/")
                        else
                                self.add("case {self.compiler.classid(t)}:")
                        end
                        var recv2 = self.autoadapt(recv, t)
                        var ta = a.intro.static_mtype.as(not null)
                        ta = self.resolve_for(ta, recv2)
                        self.add("((struct {t.c_name}*){recv})->{a.intro.c_name} = {self.autobox(value, ta)};")
                        self.add("break;")
                end
                if self.compiler.hardening then
                        self.add("default: /* Bug*/")
                        self.bugtype(recv)
                end
                self.add("\}")
        end

        redef fun init_instance(mtype)
        do
                mtype = self.anchor(mtype).as(MClassType)
                if not self.compiler.runtime_type_analysis.live_types.has(mtype) then
                        debug "problem: {mtype} was detected dead"
                end
                var res = self.new_expr("NEW_{mtype.c_name}()", mtype)
                res.is_exact = true
                return res
        end

        redef fun type_test(value, mtype, tag)
        do
                mtype = self.anchor(mtype)
                if not self.compiler.runtime_type_analysis.live_cast_types.has(mtype) then
                        debug "problem: {mtype} was detected cast-dead"
                        abort
                end

                var types = self.collect_types(value)
                var res = self.new_var(bool_type)

                self.add("/* isa {mtype} on {value.inspect} */")
                if value.mtype.ctype != "val*" then
                        if value.mtype.is_subtype(self.compiler.mainmodule, null, mtype) then
                                self.add("{res} = 1;")
                        else
                                self.add("{res} = 0;")
                        end
                        return res
                end
                if value.mcasttype isa MNullableType or value.mcasttype isa MNullType then
                        self.add("if ({value} == NULL) \{")
                        if mtype isa MNullableType then
                                self.add("{res} = 1; /* isa {mtype} */")
                        else
                                self.add("{res} = 0; /* not isa {mtype} */")
                        end
                        self.add("\} else ")
                end
                self.add("switch({value}->classid) \{")
                for t in types do
                        if t.is_subtype(self.compiler.mainmodule, null, mtype) then
                                self.add("case {self.compiler.classid(t)}: /* {t} */")
                        end
                end
                self.add("{res} = 1;")
                self.add("break;")
                self.add("default:")
                self.add("{res} = 0;")
                self.add("\}")

                return res
        end

        redef fun is_same_type_test(value1, value2)
        do
                var res = self.new_var(bool_type)
                if value2.mtype.ctype == "val*" then
                        if value1.mtype.ctype == "val*" then
                                self.add "{res} = {value1}->classid == {value2}->classid;"
                        else
                                self.add "{res} = {self.compiler.classid(value1.mtype.as(MClassType))} == {value2}->classid;"
                        end
                else
                        if value1.mtype.ctype == "val*" then
                                self.add "{res} = {value1}->classid == {self.compiler.classid(value2.mtype.as(MClassType))};"
                        else if value1.mcasttype == value2.mcasttype then
                                self.add "{res} = 1;"
                        else
                                self.add "{res} = 0;"
                        end
                end
                return res
        end

        redef fun class_name_string(value)
        do
                var res = self.get_name("var_class_name")
                self.add_decl("const char* {res};")
                if value.mtype.ctype == "val*" then
                        self.add "{res} = class_names[{value}->classid];"
                else
                        self.add "{res} = class_names[{self.compiler.classid(value.mtype.as(MClassType))}];"
                end
                return res
        end

        redef fun equal_test(value1, value2)
        do
                var res = self.new_var(bool_type)
                if value2.mtype.ctype != "val*" and value1.mtype.ctype == "val*" then
                        var tmp = value1
                        value1 = value2
                        value2 = tmp
                end
                if value1.mtype.ctype != "val*" then
                        if value2.mtype == value1.mtype then
                                self.add("{res} = {value1} == {value2};")
                        else if value2.mtype.ctype != "val*" then
                                self.add("{res} = 0; /* incompatible types {value1.mtype} vs. {value2.mtype}*/")
                        else
                                var mtype1 = value1.mtype.as(MClassType)
                                self.add("{res} = ({value2} != NULL) && ({value2}->classid == {self.compiler.classid(mtype1)});")
                                self.add("if ({res}) \{")
                                self.add("{res} = ({self.autobox(value2, value1.mtype)} == {value1});")
                                self.add("\}")
                        end
                else
                        var s = new Array[String]
                        for t in self.compiler.live_primitive_types do
                                if not t.is_subtype(self.compiler.mainmodule, null, value1.mcasttype) then continue
                                if not t.is_subtype(self.compiler.mainmodule, null, value2.mcasttype) then continue
                                s.add "({value1}->classid == {self.compiler.classid(t)} && ((struct {t.c_name}*){value1})->value == ((struct {t.c_name}*){value2})->value)"
                        end
                        if s.is_empty then
                                self.add("{res} = {value1} == {value2};")
                        else
                                self.add("{res} = {value1} == {value2} || ({value1} != NULL && {value2} != NULL && {value1}->classid == {value2}->classid && ({s.join(" || ")}));")
                        end
                end
                return res
        end

        redef fun array_instance(array, elttype)
        do
                elttype = self.anchor(elttype)
                var arraytype = self.get_class("Array").get_mtype([elttype])
                var res = self.init_instance(arraytype)
                self.add("\{ /* {res} = array_instance Array[{elttype}] */")
                var nat = self.new_var(self.get_class("NativeArray").get_mtype([elttype]))
                nat.is_exact = true
                self.add("{nat} = NEW_{nat.mtype.c_name}({array.length});")
                for i in [0..array.length[ do
                        var r = self.autobox(array[i], elttype)
                        self.add("((struct {nat.mtype.c_name}*) {nat})->values[{i}] = {r};")
                end
                var length = self.int_instance(array.length)
                self.send(self.get_property("with_native", arraytype), [res, nat, length])
                self.add("\}")
                return res
        end
end

# A runtime function customized on a specific monomrph receiver type
private class CustomizedRuntimeFunction
        super AbstractRuntimeFunction

        redef type COMPILER: GlobalCompiler
        redef type VISITOR: GlobalCompilerVisitor

        # The considered reciever
        # (usually is a live type but no strong guarantee)
        var recv: MClassType

        init(mmethoddef: MMethodDef, recv: MClassType)
        do
                super(mmethoddef)
                self.recv = recv
        end

        redef fun build_c_name
        do
                var res = self.c_name_cache
                if res != null then return res
                if self.mmethoddef.mclassdef.bound_mtype == self.recv then
                        res = self.mmethoddef.c_name
                else
                        res = "{mmethoddef.c_name}__{recv.c_name}"
                end
                self.c_name_cache = res
                return res
        end

        # used in the compiler worklist
        redef fun ==(o)
        do
                if not o isa CustomizedRuntimeFunction then return false
                if self.mmethoddef != o.mmethoddef then return false
                if self.recv != o.recv then return false
                return true
        end

        # used in the compiler work-list
        redef fun hash do return self.mmethoddef.hash + self.recv.hash

        redef fun to_s
        do
                if self.mmethoddef.mclassdef.bound_mtype == self.recv then
                        return self.mmethoddef.to_s
                else
                        return "{self.mmethoddef}@{self.recv}"
                end
        end

        # compile the code customized for the reciever
        redef fun compile_to_c(compiler)
        do
                var recv = self.recv
                var mmethoddef = self.mmethoddef
                if not recv.is_subtype(compiler.mainmodule, null, mmethoddef.mclassdef.bound_mtype) then
                        print("problem: why do we compile {self} for {recv}?")
                        abort
                end

                var v = compiler.new_visitor
                var selfvar = new RuntimeVariable("self", recv, recv)
                if compiler.runtime_type_analysis.live_types.has(recv) then
                        selfvar.is_exact = true
                end
                var arguments = new Array[RuntimeVariable]
                var frame = new Frame(v, mmethoddef, recv, arguments)
                v.frame = frame

                var sig = new FlatBuffer
                var comment = new FlatBuffer
                var ret = mmethoddef.msignature.return_mtype
                if ret != null then
                        ret = v.resolve_for(ret, selfvar)
                        sig.append("{ret.ctype} ")
                else if mmethoddef.mproperty.is_new then
                        ret = recv
                        sig.append("{ret.ctype} ")
                else
                        sig.append("void ")
                end
                sig.append(self.c_name)
                sig.append("({recv.ctype} {selfvar}")
                comment.append("(self: {recv}")
                arguments.add(selfvar)
                for i in [0..mmethoddef.msignature.arity[ do
                        var mtype = mmethoddef.msignature.mparameters[i].mtype
                        if i == mmethoddef.msignature.vararg_rank then
                                mtype = v.get_class("Array").get_mtype([mtype])
                        end
                        mtype = v.resolve_for(mtype, selfvar)
                        comment.append(", {mtype}")
                        sig.append(", {mtype.ctype} p{i}")
                        var argvar = new RuntimeVariable("p{i}", mtype, mtype)
                        arguments.add(argvar)
                end
                sig.append(")")
                comment.append(")")
                if ret != null then
                        comment.append(": {ret}")
                end
                compiler.header.add_decl("{sig};")

                v.add_decl("/* method {self} for {comment} */")
                v.add_decl("{sig} \{")
                #v.add("printf(\"method {self} for {comment}\\n\");")
                if ret != null then
                        frame.returnvar = v.new_var(ret)
                end
                frame.returnlabel = v.get_name("RET_LABEL")

                mmethoddef.compile_inside_to_c(v, arguments)

                v.add("{frame.returnlabel.as(not null)}:;")
                if ret != null then
                        v.add("return {frame.returnvar.as(not null)};")
                end
                v.add("\}")
                if not self.c_name.has_substring("VIRTUAL", 0) then compiler.names[self.c_name] = "{mmethoddef.mclassdef.mmodule.name}::{mmethoddef.mclassdef.mclass.name}::{mmethoddef.mproperty.name} ({mmethoddef.location.file.filename}:{mmethoddef.location.line_start})"
        end

        redef fun call(v: VISITOR, arguments: Array[RuntimeVariable]): nullable RuntimeVariable
        do
                var ret = self.mmethoddef.msignature.return_mtype
                if self.mmethoddef.mproperty.is_new then
                        ret = recv
                end
                if ret != null then
                        ret = v.resolve_for(ret, arguments.first)
                end
                if self.mmethoddef.can_inline(v) then
                        var frame = new Frame(v, self.mmethoddef, self.recv, arguments)
                        frame.returnlabel = v.get_name("RET_LABEL")
                        if ret != null then
                                frame.returnvar = v.new_var(ret)
                        end
                        var old_frame = v.frame
                        v.frame = frame
                        v.add("\{ /* Inline {self} ({arguments.join(",")}) */")
                        self.mmethoddef.compile_inside_to_c(v, arguments)
                        v.add("{frame.returnlabel.as(not null)}:(void)0;")
                        v.add("\}")
                        v.frame = old_frame
                        return frame.returnvar
                end
                v.adapt_signature(self.mmethoddef, arguments)
                v.compiler.todo(self)
                if ret == null then
                        v.add("{self.c_name}({arguments.join(",")});")
                        return null
                else
                        var res = v.new_var(ret)
                        v.add("{res} = {self.c_name}({arguments.join(",")});")
                        return res
                end
        end
end