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

# This file is part of NIT ( http://www.nitlanguage.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.

# Separate compilation of a Nit program with generic type erasure
module separate_erasure_compiler

intrude import separate_compiler

# Add separate erased compiler specific options
redef class ToolContext
        # --erasure
        var opt_erasure = new OptionBool("Erase generic types", "--erasure")
        # --rta
        var opt_rta = new OptionBool("Activate RTA (implicit with --global and --separate)", "--rta")
        # --no-check-erasure-cast
        var opt_no_check_erasure_cast = new OptionBool("Disable implicit casts on unsafe return with erasure-typing policy (dangerous)", "--no-check-erasure-cast")

        redef init
        do
                super
                self.option_context.add_option(self.opt_erasure, self.opt_no_check_erasure_cast, opt_rta)
        end

        redef fun process_options(args)
        do
                super

                if opt_no_check_all.value then
                        opt_no_check_erasure_cast.value = true
                end

                # Temporary disabled. TODO: implement tagging in the erasure compiler.
                if opt_erasure.value then
                        opt_no_tag_primitives.value = true
                end
        end

        var erasure_compiler_phase = new ErasureCompilerPhase(self, null)
end

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

                var modelbuilder = toolcontext.modelbuilder
                var analysis = null
                if toolcontext.opt_rta.value then
                        analysis = modelbuilder.do_rapid_type_analysis(mainmodule)
                end
                modelbuilder.run_separate_erasure_compiler(mainmodule, analysis)
        end
end

redef class ModelBuilder
        fun run_separate_erasure_compiler(mainmodule: MModule, runtime_type_analysis: nullable RapidTypeAnalysis)
        do
                var time0 = get_time
                self.toolcontext.info("*** GENERATING C ***", 1)

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

class SeparateErasureCompiler
        super SeparateCompiler

        private var class_ids: Map[MClass, Int] is noinit
        private var class_colors: Map[MClass, Int] is noinit
        protected var vt_colors: Map[MVirtualTypeProp, Int] is noinit

        init do

                # Class coloring
                var poset = mainmodule.flatten_mclass_hierarchy
                var mclasses = new HashSet[MClass].from(poset)
                var colorer = new POSetColorer[MClass]
                colorer.colorize(poset)
                class_ids = colorer.ids
                class_colors = colorer.colors
                class_tables = self.build_class_typing_tables(mclasses)

                # lookup vt to build layout with
                var vts = new HashMap[MClass, Set[MVirtualTypeProp]]
                for mclass in mclasses do
                        vts[mclass] = new HashSet[MVirtualTypeProp]
                        for mprop in self.mainmodule.properties(mclass) do
                                if mprop isa MVirtualTypeProp then
                                        vts[mclass].add(mprop)
                                end
                        end
                end

                # vt coloration
                var vt_colorer = new POSetBucketsColorer[MClass, MVirtualTypeProp](poset, colorer.conflicts)
                vt_colors = vt_colorer.colorize(vts)
                vt_tables = build_vt_tables(mclasses)
        end

        fun build_vt_tables(mclasses: Set[MClass]): Map[MClass, Array[nullable MPropDef]] do
                var tables = new HashMap[MClass, Array[nullable MPropDef]]
                for mclass in mclasses do
                        var table = new Array[nullable MPropDef]
                        # first, fill table from parents by reverse linearization order
                        var parents = new Array[MClass]
                        if mainmodule.flatten_mclass_hierarchy.has(mclass) then
                                parents = mclass.in_hierarchy(mainmodule).greaters.to_a
                                self.mainmodule.linearize_mclasses(parents)
                        end
                        for parent in parents do
                                if parent == mclass then continue
                                for mproperty in self.mainmodule.properties(parent) do
                                        if not mproperty isa MVirtualTypeProp then continue
                                        var color = vt_colors[mproperty]
                                        if table.length <= color then
                                                for i in [table.length .. color[ do
                                                        table[i] = null
                                                end
                                        end
                                        for mpropdef in mproperty.mpropdefs do
                                                if mpropdef.mclassdef.mclass == parent then
                                                        table[color] = mpropdef
                                                end
                                        end
                                end
                        end

                        # then override with local properties
                        for mproperty in self.mainmodule.properties(mclass) do
                                if not mproperty isa MVirtualTypeProp then continue
                                var color = vt_colors[mproperty]
                                if table.length <= color then
                                        for i in [table.length .. color[ do
                                                table[i] = null
                                        end
                                end
                                for mpropdef in mproperty.mpropdefs do
                                        if mpropdef.mclassdef.mclass == mclass then
                                                table[color] = mpropdef
                                        end
                                end
                        end
                        tables[mclass] = table
                end
                return tables
        end

        # Build class tables
        fun build_class_typing_tables(mclasses: Set[MClass]): Map[MClass, Array[nullable MClass]] do
                var tables = new HashMap[MClass, Array[nullable MClass]]
                for mclass in mclasses do
                        var table = new Array[nullable MClass]
                        var supers = new Array[MClass]
                        if mainmodule.flatten_mclass_hierarchy.has(mclass) then
                                supers = mclass.in_hierarchy(mainmodule).greaters.to_a
                        end
                        for sup in supers do
                                var color = class_colors[sup]
                                if table.length <= color then
                                        for i in [table.length .. color[ do
                                                table[i] = null
                                        end
                                end
                                table[color] = sup
                        end
                        tables[mclass] = table
                end
                return tables
        end

        redef fun compile_header_structs do
                self.header.add_decl("typedef void(*nitmethod_t)(void); /* general C type representing a Nit method. */")
                self.compile_header_attribute_structs
                self.header.add_decl("struct class \{ int id; const char *name; int box_kind; int color; const struct vts_table *vts_table; const struct type_table *type_table; nitmethod_t vft[]; \}; /* general C type representing a Nit class. */")
                self.header.add_decl("struct type_table \{ int size; int table[]; \}; /* colorized type table. */")
                self.header.add_decl("struct vts_entry \{ short int is_nullable; const struct class *class; \}; /* link (nullable or not) between the vts and is bound. */")
                self.header.add_decl("struct vts_table \{ int dummy; const struct vts_entry vts[]; \}; /* vts list of a C type representation. */")
                self.header.add_decl("typedef struct instance \{ const struct class *class; nitattribute_t attrs[1]; \} val; /* general C type representing a Nit instance. */")
        end

        redef fun compile_class_to_c(mclass: MClass)
        do
                var mtype = mclass.intro.bound_mtype
                var c_name = mclass.c_name

                var class_table = self.class_tables[mclass]
                var v = self.new_visitor

                var rta = runtime_type_analysis
                var is_dead = false # mclass.kind == abstract_kind or mclass.kind == interface_kind
                if not is_dead and rta != null and not rta.live_classes.has(mclass) and not mtype.is_c_primitive and mclass.name != "NativeArray" then
                        is_dead = true
                end

                v.add_decl("/* runtime class {c_name} */")

                self.provide_declaration("class_{c_name}", "extern const struct class class_{c_name};")
                v.add_decl("extern const struct type_table type_table_{c_name};")

                # Build class vft
                v.add_decl("const struct class class_{c_name} = \{")
                v.add_decl("{class_ids[mclass]},")
                v.add_decl("\"{mclass.name}\", /* class_name_string */")
                v.add_decl("{self.box_kind_of(mclass)}, /* box_kind */")
                v.add_decl("{class_colors[mclass]},")
                if not is_dead then
                        if build_class_vts_table(mclass) then
                                v.require_declaration("vts_table_{c_name}")
                                v.add_decl("&vts_table_{c_name},")
                        else
                                v.add_decl("NULL,")
                        end
                        v.add_decl("&type_table_{c_name},")
                        v.add_decl("\{")
                        var vft = self.method_tables.get_or_null(mclass)
                        if vft != null then for i in [0 .. vft.length[ do
                                var mpropdef = vft[i]
                                if mpropdef == null then
                                        v.add_decl("NULL, /* empty */")
                                else
                                        assert mpropdef isa MMethodDef
                                        if rta != null and not rta.live_methoddefs.has(mpropdef) then
                                                v.add_decl("NULL, /* DEAD {mclass.intro_mmodule}:{mclass}:{mpropdef} */")
                                                continue
                                        end
                                        var rf = mpropdef.virtual_runtime_function
                                        v.require_declaration(rf.c_name)
                                        v.add_decl("(nitmethod_t){rf.c_name}, /* pointer to {mpropdef.full_name} */")
                                end
                        end
                        v.add_decl("\}")
                end
                v.add_decl("\};")

                # Build class type table

                v.add_decl("const struct type_table type_table_{c_name} = \{")
                v.add_decl("{class_table.length},")
                v.add_decl("\{")
                for msuper in class_table do
                        if msuper == null then
                                v.add_decl("-1, /* empty */")
                        else
                                v.add_decl("{self.class_ids[msuper]}, /* {msuper} */")
                        end
                end
                v.add_decl("\}")
                v.add_decl("\};")

                if mtype.is_c_primitive or mtype.mclass.name == "Pointer" then
                        #Build instance struct
                        self.header.add_decl("struct instance_{c_name} \{")
                        self.header.add_decl("const struct class *class;")
                        self.header.add_decl("{mtype.ctype} value;")
                        self.header.add_decl("\};")

                        #Build BOX
                        self.provide_declaration("BOX_{c_name}", "val* BOX_{c_name}({mtype.ctype_extern});")
                        v.add_decl("/* allocate {mtype} */")
                        v.add_decl("val* BOX_{mtype.c_name}({mtype.ctype_extern} value) \{")
                        v.add("struct instance_{c_name}*res = nit_alloc(sizeof(struct instance_{c_name}));")
                        v.require_declaration("class_{c_name}")
                        v.add("res->class = &class_{c_name};")
                        v.add("res->value = value;")
                        v.add("return (val*)res;")
                        v.add("\}")

                        if mtype.mclass.name != "Pointer" then return

                        v = new_visitor
                        self.provide_declaration("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}();")
                        v.add_decl("/* allocate {mtype} */")
                        v.add_decl("{mtype.ctype} NEW_{c_name}() \{")
                        if is_dead then
                                v.add_abort("{mclass} is DEAD")
                        else
                                var res = v.new_named_var(mtype, "self")
                                res.is_exact = true
                                v.add("{res} = nit_alloc(sizeof(struct instance_{mtype.c_name}));")
                                v.require_declaration("class_{c_name}")
                                v.add("{res}->class = &class_{c_name};")
                                v.add("((struct instance_{mtype.c_name}*){res})->value = NULL;")
                                v.add("return {res};")
                        end
                        v.add("\}")
                        return
                else if mclass.name == "NativeArray" then
                        #Build instance struct
                        self.header.add_decl("struct instance_{c_name} \{")
                        self.header.add_decl("const struct class *class;")
                        self.header.add_decl("int length;")
                        self.header.add_decl("val* values[];")
                        self.header.add_decl("\};")

                        #Build NEW
                        self.provide_declaration("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}(int length);")
                        v.add_decl("/* allocate {mtype} */")
                        v.add_decl("{mtype.ctype} NEW_{c_name}(int length) \{")
                        var res = v.get_name("self")
                        v.add_decl("struct instance_{c_name} *{res};")
                        var mtype_elt = mtype.arguments.first
                        v.add("{res} = nit_alloc(sizeof(struct instance_{c_name}) + length*sizeof({mtype_elt.ctype}));")
                        v.require_declaration("class_{c_name}")
                        v.add("{res}->class = &class_{c_name};")
                        v.add("{res}->length = length;")
                        v.add("return (val*){res};")
                        v.add("\}")
                        return
                else if mclass.name == "RoutineRef" then
                        self.header.add_decl("struct instance_{c_name} \{")
                        self.header.add_decl("const struct class *class;")
                        self.header.add_decl("val* recv;")
                        self.header.add_decl("nitmethod_t method;")
                        self.header.add_decl("\};")

                        self.provide_declaration("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}(val* recv, nitmethod_t method, const struct class* class);")
                        v.add_decl("/* allocate {mtype} */")
                        v.add_decl("{mtype.ctype} NEW_{c_name}(val* recv, nitmethod_t method, const struct class* class)\{")
                        var res = v.get_name("self")
                        v.add_decl("struct instance_{c_name} *{res};")
                        var alloc = v.nit_alloc("sizeof(struct instance_{c_name})", mclass.full_name)
                        v.add("{res} = {alloc};")
                        v.add("{res}->class = class;")
                        v.add("{res}->recv = recv;")
                        v.add("{res}->method = method;")
                        v.add("return (val*){res};")
                        v.add("\}")
                        return
                else if mtype.mclass.kind == extern_kind and mtype.mclass.name != "CString" then
                        var pointer_type = mainmodule.pointer_type

                        self.provide_declaration("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}();")
                        v.add_decl("/* allocate {mtype} */")
                        v.add_decl("{mtype.ctype} NEW_{c_name}() \{")
                        if is_dead then
                                v.add_abort("{mclass} is DEAD")
                        else
                                var res = v.new_named_var(mtype, "self")
                                res.is_exact = true
                                v.add("{res} = nit_alloc(sizeof(struct instance_{pointer_type.c_name}));")
                                #v.add("{res}->type = type;")
                                v.require_declaration("class_{c_name}")
                                v.add("{res}->class = &class_{c_name};")
                                v.add("((struct instance_{pointer_type.c_name}*){res})->value = NULL;")
                                v.add("return {res};")
                        end
                        v.add("\}")
                        return
                end

                #Build NEW
                self.provide_declaration("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}(void);")
                v.add_decl("/* allocate {mtype} */")
                v.add_decl("{mtype.ctype} NEW_{c_name}(void) \{")
                if is_dead then
                        v.add_abort("{mclass} is DEAD")
                else

                        var res = v.new_named_var(mtype, "self")
                        res.is_exact = true
                        var attrs = self.attr_tables.get_or_null(mclass)
                        if attrs == null then
                                v.add("{res} = nit_alloc(sizeof(struct instance));")
                        else
                                v.add("{res} = nit_alloc(sizeof(struct instance) + {attrs.length}*sizeof(nitattribute_t));")
                        end
                        v.require_declaration("class_{c_name}")
                        v.add("{res}->class = &class_{c_name};")
                        if attrs != null then
                                self.generate_init_attr(v, res, mtype)
                                v.set_finalizer res
                        end
                        v.add("return {res};")
                end
                v.add("\}")
        end

        private fun build_class_vts_table(mclass: MClass): Bool do
                if self.vt_tables[mclass].is_empty then return false

                self.provide_declaration("vts_table_{mclass.c_name}", "extern const struct vts_table vts_table_{mclass.c_name};")

                var v = new_visitor
                v.add_decl("const struct vts_table vts_table_{mclass.c_name} = \{")
                v.add_decl("0, /* dummy */")
                v.add_decl("\{")

                for vt in self.vt_tables[mclass] do
                        if vt == null then
                                v.add_decl("\{-1, NULL\}, /* empty */")
                        else
                                var is_null = 0
                                var bound = retrieve_vt_bound(mclass.intro.bound_mtype, vt.as(MVirtualTypeDef).bound)
                                while bound isa MNullableType do
                                        bound = retrieve_vt_bound(mclass.intro.bound_mtype, bound.mtype)
                                        is_null = 1
                                end
                                var vtclass = bound.as(MClassType).mclass
                                v.require_declaration("class_{vtclass.c_name}")
                                v.add_decl("\{{is_null}, &class_{vtclass.c_name}\}, /* {vt} */")
                        end
                end
                v.add_decl("\},")
                v.add_decl("\};")
                return true
        end

        private fun retrieve_vt_bound(anchor: MClassType, mtype: nullable MType): MType do
                if mtype == null then
                        print "NOT YET IMPLEMENTED: retrieve_vt_bound on null"
                        abort
                end
                if mtype isa MVirtualType then
                        return mtype.anchor_to(mainmodule, anchor)
                else if mtype isa MParameterType then
                        return mtype.anchor_to(mainmodule, anchor)
                else
                        return mtype
                end
        end

        redef fun compile_types
        do
                compile_color_consts(vt_colors)
        end

        redef fun new_visitor do return new SeparateErasureCompilerVisitor(self)

        # Stats

        private var class_tables: Map[MClass, Array[nullable MClass]] is noinit
        private var vt_tables: Map[MClass, Array[nullable MPropDef]] is noinit

        redef fun display_sizes
        do
                print "# size of subtyping tables"
                print "\ttotal \tholes"
                var total = 0
                var holes = 0
                for t, table in class_tables do
                        total += table.length
                        for e in table do if e == null then holes += 1
                end
                print "\t{total}\t{holes}"

                print "# size of resolution tables"
                print "\ttotal \tholes"
                total = 0
                holes = 0
                for t, table in vt_tables do
                        total += table.length
                        for e in table do if e == null then holes += 1
                end
                print "\t{total}\t{holes}"

                print "# size of methods tables"
                print "\ttotal \tholes"
                total = 0
                holes = 0
                for t, table in method_tables do
                        total += table.length
                        for e in table do if e == null then holes += 1
                end
                print "\t{total}\t{holes}"

                print "# size of attributes tables"
                print "\ttotal \tholes"
                total = 0
                holes = 0
                for t, table in attr_tables do
                        total += table.length
                        for e in table do if e == null then holes += 1
                end
                print "\t{total}\t{holes}"
        end
end

class SeparateErasureCompilerVisitor
        super SeparateCompilerVisitor

        redef fun compile_callsite(callsite, arguments)
        do
                var res = super
                if callsite.erasure_cast and not self.compiler.as(SeparateErasureCompiler).modelbuilder.toolcontext.opt_no_check_erasure_cast.value then
                        assert res != null
                        var mtype = callsite.msignature.return_mtype
                        assert mtype != null
                        self.add("/* Erasure cast for return {res} isa {mtype} */")
                        var cond = self.type_test(res, mtype, "erasure")
                        self.add("if (!{cond}) \{")
                        #var x = self.class_name_string(res)
                        #var y = self.class_name_string(arguments.first)
                        #self.add("PRINT_ERROR(\"Erasure cast: expected {mtype} (self is %s), got %s for {res}\\n\", {y}, {x});")
                        self.add_abort("Cast failed")
                        self.add("\}")
                end
                return res
        end

        redef fun init_instance(mtype)
        do
                self.require_declaration("NEW_{mtype.mclass.c_name}")
                return self.new_expr("NEW_{mtype.mclass.c_name}()", mtype)
        end

        redef fun type_test(value, mtype, tag)
        do
                self.add("/* type test for {value.inspect} isa {mtype} */")

                var res = self.new_var(bool_type)

                var cltype = self.get_name("cltype")
                self.add_decl("int {cltype};")
                var idtype = self.get_name("idtype")
                self.add_decl("int {idtype};")

                var maybe_null = self.maybe_null(value)
                var accept_null = "0"
                if mtype isa MNullableType then
                        mtype = mtype.mtype
                        accept_null = "1"
                end
                if mtype isa MParameterType then
                        # Here we get the bound of the the formal type (eh, erasure...)
                        mtype = mtype.resolve_for(self.frame.mpropdef.mclassdef.bound_mtype, self.frame.mpropdef.mclassdef.bound_mtype, self.frame.mpropdef.mclassdef.mmodule, false)
                        if mtype isa MNullableType then
                                mtype = mtype.mtype
                                accept_null = "1"
                        end
                end

                if value.mcasttype.is_subtype(self.frame.mpropdef.mclassdef.mmodule, self.frame.mpropdef.mclassdef.bound_mtype, mtype) then
                        self.add("{res} = 1; /* easy {value.inspect} isa {mtype}*/")
                        if compiler.modelbuilder.toolcontext.opt_typing_test_metrics.value then
                                self.compiler.count_type_test_skipped[tag] += 1
                                self.add("count_type_test_skipped_{tag}++;")
                        end
                        return res
                end

                var class_ptr
                if not value.mtype.is_c_primitive then
                        class_ptr = "{value}->class->"
                else
                        var mclass = value.mtype.as(MClassType).mclass
                        self.require_declaration("class_{mclass.c_name}")
                        class_ptr = "class_{mclass.c_name}."
                end

                if mtype isa MClassType then
                        self.require_declaration("class_{mtype.mclass.c_name}")
                        self.add("{cltype} = class_{mtype.mclass.c_name}.color;")
                        self.add("{idtype} = class_{mtype.mclass.c_name}.id;")
                        if compiler.modelbuilder.toolcontext.opt_typing_test_metrics.value then
                                self.compiler.count_type_test_resolved[tag] += 1
                                self.add("count_type_test_resolved_{tag}++;")
                        end
                else if mtype isa MVirtualType then
                        var recv = self.frame.arguments.first
                        var recv_ptr
                        if not recv.mtype.is_c_primitive then
                                recv_ptr = "{recv}->class->"
                        else
                                var mclass = recv.mtype.as(MClassType).mclass
                                self.require_declaration("class_{mclass.c_name}")
                                recv_ptr = "class_{mclass.c_name}."
                        end
                        var entry = self.get_name("entry")
                        self.add("struct vts_entry {entry};")
                        self.require_declaration(mtype.mproperty.const_color)
                        self.add("{entry} = {recv_ptr}vts_table->vts[{mtype.mproperty.const_color}];")
                        self.add("{cltype} = {entry}.class->color;")
                        self.add("{idtype} = {entry}.class->id;")
                        if maybe_null and accept_null == "0" then
                                var is_nullable = self.get_name("is_nullable")
                                self.add_decl("short int {is_nullable};")
                                self.add("{is_nullable} = {entry}.is_nullable;")
                                accept_null = is_nullable.to_s
                        end
                        if compiler.modelbuilder.toolcontext.opt_typing_test_metrics.value then
                                self.compiler.count_type_test_unresolved[tag] += 1
                                self.add("count_type_test_unresolved_{tag}++;")
                        end
                else
                        self.debug("type_test({value.inspect}, {mtype})")
                        abort
                end

                # check color is in table
                if maybe_null then
                        self.add("if({value} == NULL) \{")
                        self.add("{res} = {accept_null};")
                        self.add("\} else \{")
                end
                self.add("if({cltype} >= {class_ptr}type_table->size) \{")
                self.add("{res} = 0;")
                self.add("\} else \{")
                self.add("{res} = {class_ptr}type_table->table[{cltype}] == {idtype};")
                self.add("\}")
                if maybe_null then
                        self.add("\}")
                end

                return res
        end

        redef fun unbox_extern(value, mtype)
        do
                if mtype isa MClassType and mtype.mclass.kind == extern_kind and
                   mtype.mclass.name != "CString" then
                        var pointer_type = compiler.mainmodule.pointer_type
                        var res = self.new_var_extern(mtype)
                        self.add "{res} = ((struct instance_{pointer_type.c_name}*){value})->value; /* unboxing {value.mtype} */"
                        return res
                else
                        return value
                end
        end

        redef fun box_extern(value, mtype)
        do
                if mtype isa MClassType and mtype.mclass.kind == extern_kind and
                   mtype.mclass.name != "CString" then
                        var valtype = compiler.mainmodule.pointer_type
                        var res = self.new_var(mtype)
                        if compiler.runtime_type_analysis != null and not compiler.runtime_type_analysis.live_types.has(value.mtype.as(MClassType)) then
                                self.add("/*no boxing of {value.mtype}: {value.mtype} is not live! */")
                                self.add("PRINT_ERROR(\"Dead code executed!\\n\"); fatal_exit(1);")
                                return res
                        end
                        self.require_declaration("BOX_{valtype.c_name}")
                        self.add("{res} = BOX_{valtype.c_name}({value}); /* boxing {value.mtype} */")
                        self.require_declaration("class_{mtype.c_name}")
                        self.add("{res}->class = &class_{mtype.c_name};")
                        return res
                else
                        return value
                end
        end

        redef fun class_name_string(value)
        do
                var res = self.get_name("var_class_name")
                self.add_decl("const char* {res};")
                if not value.mtype.is_c_primitive then
                        self.add "{res} = {value} == NULL ? \"null\" : {value}->class->name;"
                else
                        self.require_declaration("class_{value.mtype.c_name}")
                        self.add "{res} = class_{value.mtype.c_name}.name;"
                end
                return res
        end

        redef fun native_array_instance(elttype, length)
        do
                var nclass = mmodule.native_array_class
                var mtype = nclass.get_mtype([elttype])
                var res = self.new_var(mtype)
                res.is_exact = true
                self.require_declaration("NEW_{nclass.c_name}")
                length = autobox(length, compiler.mainmodule.int_type)
                self.add("{res} = NEW_{nclass.c_name}({length});")
                return res
        end

        redef fun routine_ref_instance(routine_type, recv, mmethoddef)
        do
                #debug "ENTER ref_instance"
                var mmethod = mmethoddef.mproperty
                # routine_mclass is the specialized one, e.g: FunRef1, ProcRef2, etc..
                var routine_mclass = routine_type.mclass

                var nclasses = mmodule.model.get_mclasses_by_name("RoutineRef").as(not null)
                var base_routine_mclass = nclasses.first

                # All routine classes use the same `NEW` constructor.
                # However, they have different declared `class` and `type` value.
                self.require_declaration("NEW_{base_routine_mclass.c_name}")

                var recv_class_cname = recv.mcasttype.as(MClassType).mclass.c_name
                var my_recv = recv

                if recv.mtype.is_c_primitive then
                        my_recv = autobox(recv, mmodule.object_type)
                end
                var my_recv_mclass_type = my_recv.mtype.as(MClassType)

                # The class of the concrete Routine must exist (e.g ProcRef0, FunRef0, etc.)
                self.require_declaration("class_{routine_mclass.c_name}")

                self.require_declaration(mmethoddef.c_name)

                var thunk_function = mmethoddef.callref_thunk(my_recv_mclass_type)
                var runtime_function = mmethoddef.virtual_runtime_function

                var is_c_equiv = runtime_function.msignature.c_equiv(thunk_function.msignature)

                var c_ref = thunk_function.c_ref
                if is_c_equiv then
                        var const_color = mmethoddef.mproperty.const_color
                        c_ref = "{class_info(my_recv)}->vft[{const_color}]"
                        self.require_declaration(const_color)
                else
                        self.require_declaration(thunk_function.c_name)
                        compiler.thunk_todo(thunk_function)
                end
                compiler.thunk_todo(thunk_function)

                # Each RoutineRef points to a receiver AND a callref_thunk
                var res = self.new_expr("NEW_{base_routine_mclass.c_name}({my_recv}, (nitmethod_t){c_ref}, &class_{routine_mclass.c_name})", routine_type)
                #debug "LEAVING ref_instance"
                return res

        end
end