Merge: Callref compilers
[nit.git] / src / compiler / separate_compiler.nit
index 9c03910..4716dae 100644 (file)
@@ -26,18 +26,31 @@ redef class ToolContext
        # --no-inline-intern
        var opt_no_inline_intern = new OptionBool("Do not inline call to intern methods", "--no-inline-intern")
        # --no-union-attribute
        # --no-inline-intern
        var opt_no_inline_intern = new OptionBool("Do not inline call to intern methods", "--no-inline-intern")
        # --no-union-attribute
-       var opt_no_union_attribute = new OptionBool("Put primitive attibutes in a box instead of an union", "--no-union-attribute")
+       var opt_no_union_attribute = new OptionBool("Put primitive attributes in a box instead of an union", "--no-union-attribute")
        # --no-shortcut-equate
        var opt_no_shortcut_equate = new OptionBool("Always call == in a polymorphic way", "--no-shortcut-equal")
        # --no-shortcut-equate
        var opt_no_shortcut_equate = new OptionBool("Always call == in a polymorphic way", "--no-shortcut-equal")
+       # --no-tag-primitives
+       var opt_no_tag_primitives = new OptionBool("Use only boxes for primitive types", "--no-tag-primitives")
+
        # --colors-are-symbols
        # --colors-are-symbols
-       var opt_colors_are_symbols = new OptionBool("Store colors as symbols (faster)", "--colors-are-symbols")
+       var opt_colors_are_symbols = new OptionBool("Store colors as symbols instead of static data (link-boost)", "--colors-are-symbols")
+       # --trampoline-call
+       var opt_trampoline_call = new OptionBool("Use an indirection when calling", "--trampoline-call")
+       # --guard-call
+       var opt_guard_call = new OptionBool("Guard VFT calls with a direct call", "--guard-call")
+       # --substitute-monomorph
+       var opt_substitute_monomorph = new OptionBool("Replace monomorphic trampolines with direct calls (link-boost)", "--substitute-monomorph")
+       # --link-boost
+       var opt_link_boost = new OptionBool("Enable all link-boost optimizations", "--link-boost")
 
        # --inline-coloring-numbers
        var opt_inline_coloring_numbers = new OptionBool("Inline colors and ids (semi-global)", "--inline-coloring-numbers")
        # --inline-some-methods
        var opt_inline_some_methods = new OptionBool("Allow the separate compiler to inline some methods (semi-global)", "--inline-some-methods")
        # --direct-call-monomorph
 
        # --inline-coloring-numbers
        var opt_inline_coloring_numbers = new OptionBool("Inline colors and ids (semi-global)", "--inline-coloring-numbers")
        # --inline-some-methods
        var opt_inline_some_methods = new OptionBool("Allow the separate compiler to inline some methods (semi-global)", "--inline-some-methods")
        # --direct-call-monomorph
-       var opt_direct_call_monomorph = new OptionBool("Allow the separate compiler to direct call monomorph sites (semi-global)", "--direct-call-monomorph")
+       var opt_direct_call_monomorph = new OptionBool("Allow the separate compiler to direct call monomorphic sites (semi-global)", "--direct-call-monomorph")
+       # --direct-call-monomorph0
+       var opt_direct_call_monomorph0 = new OptionBool("Allow the separate compiler to direct call monomorphic sites (semi-global)", "--direct-call-monomorph0")
        # --skip-dead-methods
        var opt_skip_dead_methods = new OptionBool("Do not compile dead methods (semi-global)", "--skip-dead-methods")
        # --semi-global
        # --skip-dead-methods
        var opt_skip_dead_methods = new OptionBool("Do not compile dead methods (semi-global)", "--skip-dead-methods")
        # --semi-global
@@ -46,6 +59,8 @@ redef class ToolContext
        var opt_colo_dead_methods = new OptionBool("Force colorization of dead methods", "--colo-dead-methods")
        # --tables-metrics
        var opt_tables_metrics = new OptionBool("Enable static size measuring of tables used for vft, typing and resolution", "--tables-metrics")
        var opt_colo_dead_methods = new OptionBool("Force colorization of dead methods", "--colo-dead-methods")
        # --tables-metrics
        var opt_tables_metrics = new OptionBool("Enable static size measuring of tables used for vft, typing and resolution", "--tables-metrics")
+       # --type-poset
+       var opt_type_poset = new OptionBool("Build a poset of types to create more condensed tables", "--type-poset")
 
        redef init
        do
 
        redef init
        do
@@ -53,10 +68,13 @@ redef class ToolContext
                self.option_context.add_option(self.opt_separate)
                self.option_context.add_option(self.opt_no_inline_intern)
                self.option_context.add_option(self.opt_no_union_attribute)
                self.option_context.add_option(self.opt_separate)
                self.option_context.add_option(self.opt_no_inline_intern)
                self.option_context.add_option(self.opt_no_union_attribute)
-               self.option_context.add_option(self.opt_no_shortcut_equate, opt_colors_are_symbols)
+               self.option_context.add_option(self.opt_no_shortcut_equate)
+               self.option_context.add_option(self.opt_no_tag_primitives)
+               self.option_context.add_option(opt_colors_are_symbols, opt_trampoline_call, opt_guard_call, opt_direct_call_monomorph0, opt_substitute_monomorph, opt_link_boost)
                self.option_context.add_option(self.opt_inline_coloring_numbers, opt_inline_some_methods, opt_direct_call_monomorph, opt_skip_dead_methods, opt_semi_global)
                self.option_context.add_option(self.opt_colo_dead_methods)
                self.option_context.add_option(self.opt_tables_metrics)
                self.option_context.add_option(self.opt_inline_coloring_numbers, opt_inline_some_methods, opt_direct_call_monomorph, opt_skip_dead_methods, opt_semi_global)
                self.option_context.add_option(self.opt_colo_dead_methods)
                self.option_context.add_option(self.opt_tables_metrics)
+               self.option_context.add_option(self.opt_type_poset)
        end
 
        redef fun process_options(args)
        end
 
        redef fun process_options(args)
@@ -70,6 +88,13 @@ redef class ToolContext
                        tc.opt_direct_call_monomorph.value = true
                        tc.opt_skip_dead_methods.value = true
                end
                        tc.opt_direct_call_monomorph.value = true
                        tc.opt_skip_dead_methods.value = true
                end
+               if tc.opt_link_boost.value then
+                       tc.opt_colors_are_symbols.value = true
+                       tc.opt_substitute_monomorph.value = true
+               end
+               if tc.opt_substitute_monomorph.value then
+                       tc.opt_trampoline_call.value = true
+               end
        end
 
        var separate_compiler_phase = new SeparateCompilerPhase(self, null)
        end
 
        var separate_compiler_phase = new SeparateCompilerPhase(self, null)
@@ -124,8 +149,7 @@ class SeparateCompiler
        private var type_ids: Map[MType, Int] is noinit
        private var type_colors: Map[MType, Int] is noinit
        private var opentype_colors: Map[MType, Int] is noinit
        private var type_ids: Map[MType, Int] is noinit
        private var type_colors: Map[MType, Int] is noinit
        private var opentype_colors: Map[MType, Int] is noinit
-       protected var method_colors: Map[PropertyLayoutElement, Int] is noinit
-       protected var attr_colors: Map[MAttribute, Int] is noinit
+       private var thunks_to_compile: Set[SeparateRuntimeFunction] = new HashSet[SeparateRuntimeFunction]
 
        init do
                var file = new_file("nit.common")
 
        init do
                var file = new_file("nit.common")
@@ -144,6 +168,7 @@ class SeparateCompiler
                modelbuilder.toolcontext.info("Property coloring", 2)
                compiler.new_file("{c_name}.classes")
                compiler.do_property_coloring
                modelbuilder.toolcontext.info("Property coloring", 2)
                compiler.new_file("{c_name}.classes")
                compiler.do_property_coloring
+               compiler.compile_class_infos
                for m in mainmodule.in_importation.greaters do
                        for mclass in m.intro_mclasses do
                                #if mclass.kind == abstract_kind or mclass.kind == interface_kind then continue
                for m in mainmodule.in_importation.greaters do
                        for mclass in m.intro_mclasses do
                                #if mclass.kind == abstract_kind or mclass.kind == interface_kind then continue
@@ -156,6 +181,7 @@ class SeparateCompiler
                compiler.compile_nitni_global_ref_functions
                compiler.compile_main_function
                compiler.compile_finalizer_function
                compiler.compile_nitni_global_ref_functions
                compiler.compile_main_function
                compiler.compile_finalizer_function
+               compiler.link_mmethods
 
                # compile methods
                for m in mainmodule.in_importation.greaters do
 
                # compile methods
                for m in mainmodule.in_importation.greaters do
@@ -170,6 +196,15 @@ class SeparateCompiler
                compiler.compile_types
        end
 
                compiler.compile_types
        end
 
+       fun thunk_todo(thunk: SeparateRuntimeFunction)
+       do
+               # Concrete instance of `SeparateRuntimeFunction` are already
+               # handled by the compiler. Avoid duplicate compilation.
+               if thunk isa SeparateThunkFunction then
+                       thunks_to_compile.add(thunk)
+               end
+       end
+
        # Color and compile type structures and cast information
        fun compile_types
        do
        # Color and compile type structures and cast information
        fun compile_types
        do
@@ -197,6 +232,11 @@ class SeparateCompiler
                self.header.add_decl("struct instance \{ const struct type *type; const struct class *class; nitattribute_t attrs[]; \}; /* general C type representing a Nit instance. */")
                self.header.add_decl("struct types \{ int dummy; const struct type *types[]; \}; /* a list types (used for vts, fts and unresolved lists). */")
                self.header.add_decl("typedef struct instance val; /* general C type representing a Nit instance. */")
                self.header.add_decl("struct instance \{ const struct type *type; const struct class *class; nitattribute_t attrs[]; \}; /* general C type representing a Nit instance. */")
                self.header.add_decl("struct types \{ int dummy; const struct type *types[]; \}; /* a list types (used for vts, fts and unresolved lists). */")
                self.header.add_decl("typedef struct instance val; /* general C type representing a Nit instance. */")
+
+               if not modelbuilder.toolcontext.opt_no_tag_primitives.value then
+                       self.header.add_decl("extern const struct class *class_info[];")
+                       self.header.add_decl("extern const struct type *type_info[];")
+               end
        end
 
        fun compile_header_attribute_structs
        end
 
        fun compile_header_attribute_structs
@@ -222,10 +262,11 @@ class SeparateCompiler
        do
                # Collect all bas box class
                # FIXME: this is not completely fine with a separate compilation scheme
        do
                # Collect all bas box class
                # FIXME: this is not completely fine with a separate compilation scheme
-               for classname in ["Int", "Bool", "Char", "Float", "NativeString", "Pointer"] do
+               for classname in ["Int", "Bool", "Byte", "Char", "Float", "CString",
+                                "Pointer", "Int8", "Int16", "UInt16", "Int32", "UInt32"] do
                        var classes = self.mainmodule.model.get_mclasses_by_name(classname)
                        if classes == null then continue
                        var classes = self.mainmodule.model.get_mclasses_by_name(classname)
                        if classes == null then continue
-                       assert classes.length == 1 else print classes.join(", ")
+                       assert classes.length == 1 else print_error classes.join(", ")
                        self.box_kinds[classes.first] = self.box_kinds.length + 1
                end
        end
                        self.box_kinds[classes.first] = self.box_kinds.length + 1
                end
        end
@@ -238,12 +279,11 @@ class SeparateCompiler
                #if mclass.mclass_type.ctype == "val*" or mclass.mclass_type.is_subtype(self.mainmodule, mclass.mclass_type pointer_type) then
                if mclass.mclass_type.ctype_extern == "val*" then
                        return 0
                #if mclass.mclass_type.ctype == "val*" or mclass.mclass_type.is_subtype(self.mainmodule, mclass.mclass_type pointer_type) then
                if mclass.mclass_type.ctype_extern == "val*" then
                        return 0
-               else if mclass.kind == extern_kind and mclass.name != "NativeString" then
-                       return self.box_kinds[self.mainmodule.get_primitive_class("Pointer")]
+               else if mclass.kind == extern_kind and mclass.name != "CString" then
+                       return self.box_kinds[self.mainmodule.pointer_type.mclass]
                else
                        return self.box_kinds[mclass]
                end
                else
                        return self.box_kinds[mclass]
                end
-
        end
 
        fun compile_color_consts(colors: Map[Object, Int]) do
        end
 
        fun compile_color_consts(colors: Map[Object, Int]) do
@@ -276,186 +316,179 @@ class SeparateCompiler
 
        private var color_consts_done = new HashSet[Object]
 
 
        private var color_consts_done = new HashSet[Object]
 
+       # The conflict graph of classes used for coloration
+       var class_conflict_graph: POSetConflictGraph[MClass] is noinit
+
        # colorize classe properties
        fun do_property_coloring do
 
                var rta = runtime_type_analysis
 
        # colorize classe properties
        fun do_property_coloring do
 
                var rta = runtime_type_analysis
 
-               # Layouts
-               var poset = mainmodule.flatten_mclass_hierarchy
-               var mclasses = new HashSet[MClass].from(poset)
-               var colorer = new POSetColorer[MClass]
-               colorer.colorize(poset)
+               # Class graph
+               var mclasses = mainmodule.flatten_mclass_hierarchy
+               class_conflict_graph = mclasses.to_conflict_graph
 
 
-               # The dead methods, still need to provide a dead color symbol
-               var dead_methods = new Array[MMethod]
-
-               # lookup properties to build layout with
+               # Prepare to collect elements to color and build layout with
                var mmethods = new HashMap[MClass, Set[PropertyLayoutElement]]
                var mattributes = new HashMap[MClass, Set[MAttribute]]
                var mmethods = new HashMap[MClass, Set[PropertyLayoutElement]]
                var mattributes = new HashMap[MClass, Set[MAttribute]]
+
+               # The dead methods and super-call, still need to provide a dead color symbol
+               var dead_methods = new Array[PropertyLayoutElement]
+
                for mclass in mclasses do
                        mmethods[mclass] = new HashSet[PropertyLayoutElement]
                        mattributes[mclass] = new HashSet[MAttribute]
                for mclass in mclasses do
                        mmethods[mclass] = new HashSet[PropertyLayoutElement]
                        mattributes[mclass] = new HashSet[MAttribute]
-                       for mprop in self.mainmodule.properties(mclass) do
-                               if mprop isa MMethod then
-                                       if not modelbuilder.toolcontext.opt_colo_dead_methods.value and rta != null and not rta.live_methods.has(mprop) then
-                                               dead_methods.add(mprop)
-                                               continue
-                                       end
-                                       mmethods[mclass].add(mprop)
-                               else if mprop isa MAttribute then
-                                       mattributes[mclass].add(mprop)
-                               end
+               end
+
+               # Pre-collect known live things
+               if rta != null then
+                       for m in rta.live_methods do
+                               mmethods[m.intro_mclassdef.mclass].add m
+                       end
+                       for m in rta.live_super_sends do
+                               var mclass = m.mclassdef.mclass
+                               mmethods[mclass].add m
                        end
                end
 
                        end
                end
 
-               # Collect all super calls (dead or not)
-               var all_super_calls = new HashSet[MMethodDef]
-               for mmodule in self.mainmodule.in_importation.greaters do
-                       for mclassdef in mmodule.mclassdefs do
-                               for mpropdef in mclassdef.mpropdefs do
-                                       if not mpropdef isa MMethodDef then continue
-                                       if mpropdef.has_supercall then
-                                               all_super_calls.add(mpropdef)
+               for m in mainmodule.in_importation.greaters do for cd in m.mclassdefs do
+                       var mclass = cd.mclass
+                       # Collect methods and attributes
+                       for p in cd.intro_mproperties do
+                               if p isa MMethod then
+                                       if rta == null then
+                                               mmethods[mclass].add p
+                                       else if not rta.live_methods.has(p) then
+                                               dead_methods.add p
                                        end
                                        end
+                               else if p isa MAttribute then
+                                       mattributes[mclass].add p
                                end
                        end
                                end
                        end
-               end
 
 
-               # lookup super calls and add it to the list of mmethods to build layout with
-               var super_calls
-               if rta != null then
-                       super_calls = rta.live_super_sends
-               else
-                       super_calls = all_super_calls
-               end
-
-               for mmethoddef in super_calls do
-                       var mclass = mmethoddef.mclassdef.mclass
-                       mmethods[mclass].add(mmethoddef)
-                       for descendant in mclass.in_hierarchy(self.mainmodule).smallers do
-                               mmethods[descendant].add(mmethoddef)
+                       # Collect all super calls (dead or not)
+                       for mpropdef in cd.mpropdefs do
+                               if not mpropdef isa MMethodDef then continue
+                               if mpropdef.has_supercall then
+                                       if rta == null then
+                                               mmethods[mclass].add mpropdef
+                                       else if not rta.live_super_sends.has(mpropdef) then
+                                               dead_methods.add mpropdef
+                                       end
+                               end
                        end
                end
 
                # methods coloration
                        end
                end
 
                # methods coloration
-               var meth_colorer = new POSetBucketsColorer[MClass, PropertyLayoutElement](poset, colorer.conflicts)
-               method_colors = meth_colorer.colorize(mmethods)
-               method_tables = build_method_tables(mclasses, super_calls)
+               var meth_colorer = new POSetGroupColorer[MClass, PropertyLayoutElement](class_conflict_graph, mmethods)
+               var method_colors = meth_colorer.colors
                compile_color_consts(method_colors)
 
                compile_color_consts(method_colors)
 
-               # attribute null color to dead methods and supercalls
-               for mproperty in dead_methods do
-                       compile_color_const(new_visitor, mproperty, -1)
-               end
-               for mpropdef in all_super_calls do
-                       if super_calls.has(mpropdef) then continue
-                       compile_color_const(new_visitor, mpropdef, -1)
-               end
+               # give null color to dead methods and supercalls
+               for mproperty in dead_methods do compile_color_const(new_visitor, mproperty, -1)
 
 
-               # attributes coloration
-               var attr_colorer = new POSetBucketsColorer[MClass, MAttribute](poset, colorer.conflicts)
-               attr_colors = attr_colorer.colorize(mattributes)
-               attr_tables = build_attr_tables(mclasses)
+               # attribute coloration
+               var attr_colorer = new POSetGroupColorer[MClass, MAttribute](class_conflict_graph, mattributes)
+               var attr_colors = attr_colorer.colors#ize(poset, mattributes)
                compile_color_consts(attr_colors)
                compile_color_consts(attr_colors)
-       end
 
 
-       fun build_method_tables(mclasses: Set[MClass], super_calls: Set[MMethodDef]): Map[MClass, Array[nullable MPropDef]] do
-               var tables = new HashMap[MClass, Array[nullable MPropDef]]
+               # Build method and attribute tables
+               method_tables = new HashMap[MClass, Array[nullable MPropDef]]
+               attr_tables = new HashMap[MClass, Array[nullable MProperty]]
                for mclass in mclasses do
                for mclass in mclasses do
-                       var table = new Array[nullable MPropDef]
-                       tables[mclass] = table
+                       if not mclass.has_new_factory and (mclass.kind == abstract_kind or mclass.kind == interface_kind) then continue
+                       if rta != null and not rta.live_classes.has(mclass) then continue
 
 
-                       var mproperties = self.mainmodule.properties(mclass)
                        var mtype = mclass.intro.bound_mtype
 
                        var mtype = mclass.intro.bound_mtype
 
-                       for mproperty in mproperties do
-                               if not mproperty isa MMethod then continue
-                               if not method_colors.has_key(mproperty) then continue
-                               var color = method_colors[mproperty]
-                               if table.length <= color then
-                                       for i in [table.length .. color[ do
-                                               table[i] = null
-                                       end
-                               end
-                               table[color] = mproperty.lookup_first_definition(mainmodule, mtype)
-                       end
-
-                       for supercall in super_calls do
-                               if not mtype.collect_mclassdefs(mainmodule).has(supercall.mclassdef) then continue
-
-                               var color = method_colors[supercall]
-                               if table.length <= color then
-                                       for i in [table.length .. color[ do
-                                               table[i] = null
-                                       end
+                       # Resolve elements in the layout to get the final table
+                       var meth_layout = meth_colorer.build_layout(mclass)
+                       var meth_table = new Array[nullable MPropDef].with_capacity(meth_layout.length)
+                       method_tables[mclass] = meth_table
+                       for e in meth_layout do
+                               if e == null then
+                                       meth_table.add null
+                               else if e isa MMethod then
+                                       # Standard method call of `e`
+                                       meth_table.add e.lookup_first_definition(mainmodule, mtype)
+                               else if e isa MMethodDef then
+                                       # Super-call in the methoddef `e`
+                                       meth_table.add e.lookup_next_definition(mainmodule, mtype)
+                               else
+                                       abort
                                end
                                end
-                               var mmethoddef = supercall.lookup_next_definition(mainmodule, mtype)
-                               table[color] = mmethoddef
                        end
 
                        end
 
+                       # Do not need to resolve attributes as only the position is used
+                       attr_tables[mclass] = attr_colorer.build_layout(mclass)
                end
                end
-               return tables
-       end
 
 
-       fun build_attr_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]
-                       tables[mclass] = table
-
-                       var mproperties = self.mainmodule.properties(mclass)
-                       var mtype = mclass.intro.bound_mtype
-
-                       for mproperty in mproperties do
-                               if not mproperty isa MAttribute then continue
-                               if not attr_colors.has_key(mproperty) then continue
-                               var color = attr_colors[mproperty]
-                               if table.length <= color then
-                                       for i in [table.length .. color[ do
-                                               table[i] = null
-                                       end
-                               end
-                               table[color] = mproperty.lookup_first_definition(mainmodule, mtype)
-                       end
-               end
-               return tables
        end
 
        # colorize live types of the program
        end
 
        # colorize live types of the program
-       private fun do_type_coloring: POSet[MType] do
+       private fun do_type_coloring: Collection[MType] do
                # Collect types to colorize
                var live_types = runtime_type_analysis.live_types
                var live_cast_types = runtime_type_analysis.live_cast_types
                # Collect types to colorize
                var live_types = runtime_type_analysis.live_types
                var live_cast_types = runtime_type_analysis.live_cast_types
-               var mtypes = new HashSet[MType]
-               mtypes.add_all(live_types)
-               for c in self.box_kinds.keys do
-                       mtypes.add(c.mclass_type)
-               end
 
 
-               # Compute colors
-               var poset = poset_from_mtypes(mtypes, live_cast_types)
-               var colorer = new POSetColorer[MType]
-               colorer.colorize(poset)
-               type_ids = colorer.ids
-               type_colors = colorer.colors
-               type_tables = build_type_tables(poset)
+               var res = new HashSet[MType]
+               res.add_all live_types
+               res.add_all live_cast_types
+
+               if modelbuilder.toolcontext.opt_type_poset.value then
+                       # Compute colors with a type poset
+                       var poset = poset_from_mtypes(live_types, live_cast_types)
+                       var colorer = new POSetColorer[MType]
+                       colorer.colorize(poset)
+                       type_ids = colorer.ids
+                       type_colors = colorer.colors
+                       type_tables = build_type_tables(poset)
+               else
+                       # Compute colors using the class poset
+                       # Faster to compute but the number of holes can degenerate
+                       compute_type_test_layouts(live_types, live_cast_types)
+
+                       type_ids = new HashMap[MType, Int]
+                       for x in res do type_ids[x] = type_ids.length + 1
+               end
 
                # VT and FT are stored with other unresolved types in the big resolution_tables
 
                # VT and FT are stored with other unresolved types in the big resolution_tables
-               self.compile_resolution_tables(mtypes)
+               self.compute_resolution_tables(live_types)
 
 
-               return poset
+               return res
        end
 
        private fun poset_from_mtypes(mtypes, cast_types: Set[MType]): POSet[MType] do
                var poset = new POSet[MType]
        end
 
        private fun poset_from_mtypes(mtypes, cast_types: Set[MType]): POSet[MType] do
                var poset = new POSet[MType]
+
+               # Instead of doing the full matrix mtypes X cast_types,
+               # a grouping is done by the base classes of the type so
+               # that we compare only types whose base classes are in inheritance.
+
+               var mtypes_by_class = new MultiHashMap[MClass, MType]
                for e in mtypes do
                for e in mtypes do
+                       var c = e.undecorate.as(MClassType).mclass
+                       mtypes_by_class[c].add(e)
+                       poset.add_node(e)
+               end
+
+               var casttypes_by_class = new MultiHashMap[MClass, MType]
+               for e in cast_types do
+                       var c = e.undecorate.as(MClassType).mclass
+                       casttypes_by_class[c].add(e)
                        poset.add_node(e)
                        poset.add_node(e)
-                       for o in cast_types do
-                               if e == o then continue
-                               poset.add_node(o)
-                               if e.is_subtype(mainmodule, null, o) then
-                                       poset.add_edge(e, o)
+               end
+
+               for c1, ts1 in mtypes_by_class do
+                       for c2 in c1.in_hierarchy(mainmodule).greaters do
+                               var ts2 = casttypes_by_class[c2]
+                               for e in ts1 do
+                                       for o in ts2 do
+                                               if e == o then continue
+                                               if e.is_subtype(mainmodule, null, o) then
+                                                       poset.add_edge(e, o)
+                                               end
+                                       end
                                end
                        end
                end
                                end
                        end
                end
@@ -481,29 +514,74 @@ class SeparateCompiler
                return tables
        end
 
                return tables
        end
 
-       protected fun compile_resolution_tables(mtypes: Set[MType]) do
-               # resolution_tables is used to perform a type resolution at runtime in O(1)
+       private fun compute_type_test_layouts(mtypes: Set[MClassType], cast_types: Set[MType]) do
+               # Group cast_type by their classes
+               var bucklets = new HashMap[MClass, Set[MType]]
+               for e in cast_types do
+                       var c = e.undecorate.as(MClassType).mclass
+                       if not bucklets.has_key(c) then
+                               bucklets[c] = new HashSet[MType]
+                       end
+                       bucklets[c].add(e)
+               end
 
 
+               # Colorize cast_types from the class hierarchy
+               var colorer = new POSetGroupColorer[MClass, MType](class_conflict_graph, bucklets)
+               type_colors = colorer.colors
+
+               var layouts = new HashMap[MClass, Array[nullable MType]]
+               for c in runtime_type_analysis.live_classes do
+                       layouts[c] = colorer.build_layout(c)
+               end
+
+               # Build the table for each live type
+               for t in mtypes do
+                       # A live type use the layout of its class
+                       var c = t.mclass
+                       var layout = layouts[c]
+                       var table = new Array[nullable MType].with_capacity(layout.length)
+                       type_tables[t] = table
+
+                       # For each potential super-type in the layout
+                       for sup in layout do
+                               if sup == null then
+                                       table.add null
+                               else if t.is_subtype(mainmodule, null, sup) then
+                                       table.add sup
+                               else
+                                       table.add null
+                               end
+                       end
+               end
+       end
+
+       # resolution_tables is used to perform a type resolution at runtime in O(1)
+       private fun compute_resolution_tables(mtypes: Set[MType]) do
                # During the visit of the body of classes, live_unresolved_types are collected
                # and associated to
                # Collect all live_unresolved_types (visited in the body of classes)
 
                # Determinate fo each livetype what are its possible requested anchored types
                # During the visit of the body of classes, live_unresolved_types are collected
                # and associated to
                # Collect all live_unresolved_types (visited in the body of classes)
 
                # Determinate fo each livetype what are its possible requested anchored types
-               var mtype2unresolved = new HashMap[MClassType, Set[MType]]
+               var mtype2unresolved = new HashMap[MClass, Set[MType]]
                for mtype in self.runtime_type_analysis.live_types do
                for mtype in self.runtime_type_analysis.live_types do
-                       var set = new HashSet[MType]
+                       var mclass = mtype.mclass
+                       var set = mtype2unresolved.get_or_null(mclass)
+                       if set == null then
+                               set = new HashSet[MType]
+                               mtype2unresolved[mclass] = set
+                       end
                        for cd in mtype.collect_mclassdefs(self.mainmodule) do
                                if self.live_unresolved_types.has_key(cd) then
                                        set.add_all(self.live_unresolved_types[cd])
                                end
                        end
                        for cd in mtype.collect_mclassdefs(self.mainmodule) do
                                if self.live_unresolved_types.has_key(cd) then
                                        set.add_all(self.live_unresolved_types[cd])
                                end
                        end
-                       mtype2unresolved[mtype] = set
                end
 
                # Compute the table layout with the prefered method
                end
 
                # Compute the table layout with the prefered method
-               var colorer = new BucketsColorer[MType, MType]
+               var colorer = new BucketsColorer[MClass, MType]
+
                opentype_colors = colorer.colorize(mtype2unresolved)
                opentype_colors = colorer.colorize(mtype2unresolved)
-               resolution_tables = self.build_resolution_tables(mtype2unresolved)
+               resolution_tables = self.build_resolution_tables(self.runtime_type_analysis.live_types, mtype2unresolved)
 
                # Compile a C constant for each collected unresolved type.
                # Either to a color, or to -1 if the unresolved type is dead (no live receiver can require it)
 
                # Compile a C constant for each collected unresolved type.
                # Either to a color, or to -1 if the unresolved type is dead (no live receiver can require it)
@@ -528,9 +606,10 @@ class SeparateCompiler
                #print ""
        end
 
                #print ""
        end
 
-       fun build_resolution_tables(elements: Map[MClassType, Set[MType]]): Map[MClassType, Array[nullable MType]] do
+       fun build_resolution_tables(elements: Set[MClassType], map: Map[MClass, Set[MType]]): Map[MClassType, Array[nullable MType]] do
                var tables = new HashMap[MClassType, Array[nullable MType]]
                var tables = new HashMap[MClassType, Array[nullable MType]]
-               for mclasstype, mtypes in elements do
+               for mclasstype in elements do
+                       var mtypes = map[mclasstype.mclass]
                        var table = new Array[nullable MType]
                        for mtype in mtypes do
                                var color = opentype_colors[mtype]
                        var table = new Array[nullable MType]
                        for mtype in mtypes do
                                var color = opentype_colors[mtype]
@@ -554,6 +633,7 @@ class SeparateCompiler
                for cd in mmodule.mclassdefs do
                        for pd in cd.mpropdefs do
                                if not pd isa MMethodDef then continue
                for cd in mmodule.mclassdefs do
                        for pd in cd.mpropdefs do
                                if not pd isa MMethodDef then continue
+                               if pd.mproperty.is_broken or pd.is_broken or pd.msignature == null then continue # Skip broken method
                                var rta = runtime_type_analysis
                                if modelbuilder.toolcontext.opt_skip_dead_methods.value and rta != null and not rta.live_methoddefs.has(pd) then continue
                                #print "compile {pd} @ {cd} @ {mmodule}"
                                var rta = runtime_type_analysis
                                if modelbuilder.toolcontext.opt_skip_dead_methods.value and rta != null and not rta.live_methoddefs.has(pd) then continue
                                #print "compile {pd} @ {cd} @ {mmodule}"
@@ -561,11 +641,83 @@ class SeparateCompiler
                                r.compile_to_c(self)
                                var r2 = pd.virtual_runtime_function
                                if r2 != r then r2.compile_to_c(self)
                                r.compile_to_c(self)
                                var r2 = pd.virtual_runtime_function
                                if r2 != r then r2.compile_to_c(self)
+
+                               # Generate trampolines
+                               if modelbuilder.toolcontext.opt_trampoline_call.value then
+                                       r2.compile_trampolines(self)
+                               end
                        end
                end
                        end
                end
+               var compiled_thunks = new Array[SeparateRuntimeFunction]
+               # Compile thunks here to write them in the same module they are declared.
+               for thunk in thunks_to_compile do
+                       if thunk.mmethoddef.mclassdef.mmodule == mmodule then
+                               thunk.compile_to_c(self)
+                               compiled_thunks.add(thunk)
+                       end
+               end
+               thunks_to_compile.remove_all(compiled_thunks)
                self.mainmodule = old_module
        end
 
                self.mainmodule = old_module
        end
 
+       # Process all introduced methods and compile some linking information (if needed)
+       fun link_mmethods
+       do
+               if not modelbuilder.toolcontext.opt_substitute_monomorph.value and not modelbuilder.toolcontext.opt_guard_call.value then return
+
+               for mmodule in mainmodule.in_importation.greaters do
+                       for cd in mmodule.mclassdefs do
+                               for m in cd.intro_mproperties do
+                                       if not m isa MMethod then continue
+                                       link_mmethod(m)
+                               end
+                       end
+               end
+       end
+
+       # Compile some linking information (if needed)
+       fun link_mmethod(m: MMethod)
+       do
+               var n2 = "CALL_" + m.const_color
+
+               # Replace monomorphic call by a direct call to the virtual implementation
+               var md = is_monomorphic(m)
+               if md != null then
+                       linker_script.add("{n2} = {md.virtual_runtime_function.c_name};")
+               end
+
+               # If opt_substitute_monomorph then a trampoline is used, else a weak symbol is used
+               if modelbuilder.toolcontext.opt_guard_call.value then
+                       var r = m.intro.virtual_runtime_function
+                       provide_declaration(n2, "{r.c_ret} {n2}{r.c_sig} __attribute__((weak));")
+               end
+       end
+
+       # The single mmethodef called in case of monomorphism.
+       # Returns nul if dead or polymorphic.
+       fun is_monomorphic(m: MMethod): nullable MMethodDef
+       do
+               var rta = runtime_type_analysis
+               if rta == null then
+                       # Without RTA, monomorphic means alone (uniq name)
+                       if m.mpropdefs.length == 1 then
+                               return m.mpropdefs.first
+                       else
+                               return null
+                       end
+               else
+                       # With RTA, monomorphic means only live methoddef
+                       var res: nullable MMethodDef = null
+                       for md in m.mpropdefs do
+                               if rta.live_methoddefs.has(md) then
+                                       if res != null then return null
+                                       res = md
+                               end
+                       end
+                       return res
+               end
+       end
+
        # Globaly compile the type structure of a live type
        fun compile_type_to_c(mtype: MType)
        do
        # Globaly compile the type structure of a live type
        fun compile_type_to_c(mtype: MType)
        do
@@ -608,7 +760,7 @@ class SeparateCompiler
 
                # resolution table (for receiver)
                if is_live then
 
                # resolution table (for receiver)
                if is_live then
-                       var mclass_type = mtype.as_notnullable
+                       var mclass_type = mtype.undecorate
                        assert mclass_type isa MClassType
                        if resolution_tables[mclass_type].is_empty then
                                v.add_decl("NULL, /*NO RESOLUTIONS*/")
                        assert mclass_type isa MClassType
                        if resolution_tables[mclass_type].is_empty then
                                v.add_decl("NULL, /*NO RESOLUTIONS*/")
@@ -634,14 +786,15 @@ class SeparateCompiler
                        end
                        v.add_decl("\},")
                else
                        end
                        v.add_decl("\},")
                else
-                       v.add_decl("0, \{\}, /*DEAD TYPE*/")
+                       # Use -1 to indicate dead type, the info is used by --hardening
+                       v.add_decl("-1, \{\}, /*DEAD TYPE*/")
                end
                v.add_decl("\};")
        end
 
        fun compile_type_resolution_table(mtype: MType) do
 
                end
                v.add_decl("\};")
        end
 
        fun compile_type_resolution_table(mtype: MType) do
 
-               var mclass_type = mtype.as_notnullable.as(MClassType)
+               var mclass_type = mtype.undecorate.as(MClassType)
 
                # extern const struct resolution_table_X resolution_table_X
                self.provide_declaration("resolution_table_{mtype.c_name}", "extern const struct types resolution_table_{mtype.c_name};")
 
                # extern const struct resolution_table_X resolution_table_X
                self.provide_declaration("resolution_table_{mtype.c_name}", "extern const struct types resolution_table_{mtype.c_name};")
@@ -677,25 +830,29 @@ class SeparateCompiler
        # In a true separate compiler (a with dynamic loading) you cannot do this unfortnally
        fun compile_class_to_c(mclass: MClass)
        do
        # In a true separate compiler (a with dynamic loading) you cannot do this unfortnally
        fun compile_class_to_c(mclass: MClass)
        do
+               if mclass.is_broken then return
+
                var mtype = mclass.intro.bound_mtype
                var c_name = mclass.c_name
 
                var mtype = mclass.intro.bound_mtype
                var c_name = mclass.c_name
 
-               var vft = self.method_tables[mclass]
-               var attrs = self.attr_tables[mclass]
                var v = new_visitor
 
                var rta = runtime_type_analysis
                var v = new_visitor
 
                var rta = runtime_type_analysis
-               var is_dead = rta != null and not rta.live_classes.has(mclass) and mtype.ctype == "val*" and mclass.name != "NativeArray" and mclass.name != "Pointer"
+               var is_dead = rta != null and not rta.live_classes.has(mclass)
+               # While the class may be dead, some part of separately compiled code may use symbols associated to the class, so
+               # in order to compile and link correctly the C code, these symbols should be declared and defined.
+               var need_corpse = is_dead and mtype.is_c_primitive or mclass.kind == extern_kind or mclass.kind == enum_kind
 
 
-               v.add_decl("/* runtime class {c_name} */")
+               v.add_decl("/* runtime class {c_name}: {mclass.full_name} (dead={is_dead}; need_corpse={need_corpse})*/")
 
                # Build class vft
 
                # Build class vft
-               if not is_dead then
+               if not is_dead or need_corpse then
                        self.provide_declaration("class_{c_name}", "extern const struct class class_{c_name};")
                        v.add_decl("const struct class class_{c_name} = \{")
                        v.add_decl("{self.box_kind_of(mclass)}, /* box_kind */")
                        v.add_decl("\{")
                        self.provide_declaration("class_{c_name}", "extern const struct class class_{c_name};")
                        v.add_decl("const struct class class_{c_name} = \{")
                        v.add_decl("{self.box_kind_of(mclass)}, /* box_kind */")
                        v.add_decl("\{")
-                       for i in [0 .. vft.length[ do
+                       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 */")
                                var mpropdef = vft[i]
                                if mpropdef == null then
                                        v.add_decl("NULL, /* empty */")
@@ -704,6 +861,9 @@ class SeparateCompiler
                                        if rta != null and not rta.live_methoddefs.has(mpropdef) then
                                                v.add_decl("NULL, /* DEAD {mclass.intro_mmodule}:{mclass}:{mpropdef} */")
                                                continue
                                        if rta != null and not rta.live_methoddefs.has(mpropdef) then
                                                v.add_decl("NULL, /* DEAD {mclass.intro_mmodule}:{mclass}:{mpropdef} */")
                                                continue
+                                       else if mpropdef.is_broken or mpropdef.msignature == null or mpropdef.mproperty.is_broken then
+                                               v.add_decl("NULL, /* DEAD (BROKEN) {mclass.intro_mmodule}:{mclass}:{mpropdef} */")
+                                               continue
                                        end
                                        var rf = mpropdef.virtual_runtime_function
                                        v.require_declaration(rf.c_name)
                                        end
                                        var rf = mpropdef.virtual_runtime_function
                                        v.require_declaration(rf.c_name)
@@ -714,9 +874,11 @@ class SeparateCompiler
                        v.add_decl("\};")
                end
 
                        v.add_decl("\};")
                end
 
-               if mtype.ctype != "val*" or mtype.mclass.name == "Pointer" then
+               if mtype.is_c_primitive or mtype.mclass.name == "Pointer" then
                        # Is a primitive type or the Pointer class, not any other extern class
 
                        # Is a primitive type or the Pointer class, not any other extern class
 
+                       if mtype.is_tagged then return
+
                        #Build instance struct
                        self.header.add_decl("struct instance_{c_name} \{")
                        self.header.add_decl("const struct type *type;")
                        #Build instance struct
                        self.header.add_decl("struct instance_{c_name} \{")
                        self.header.add_decl("const struct type *type;")
@@ -724,13 +886,15 @@ class SeparateCompiler
                        self.header.add_decl("{mtype.ctype_extern} value;")
                        self.header.add_decl("\};")
 
                        self.header.add_decl("{mtype.ctype_extern} value;")
                        self.header.add_decl("\};")
 
-                       if not rta.live_types.has(mtype) and mtype.mclass.name != "Pointer" then return
+                       # Pointer is needed by extern types, live or not
+                       if is_dead and mtype.mclass.name != "Pointer" then return
 
                        #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) \{")
 
                        #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}));")
+                       var alloc = v.nit_alloc("sizeof(struct instance_{c_name})", mclass.full_name)
+                       v.add("struct instance_{c_name}*res = {alloc};")
                        v.compiler.undead_types.add(mtype)
                        v.require_declaration("type_{c_name}")
                        v.add("res->type = &type_{c_name};")
                        v.compiler.undead_types.add(mtype)
                        v.require_declaration("type_{c_name}")
                        v.add("res->type = &type_{c_name};")
@@ -740,6 +904,7 @@ class SeparateCompiler
                        v.add("return (val*)res;")
                        v.add("\}")
 
                        v.add("return (val*)res;")
                        v.add("\}")
 
+                       # A Pointer class also need its constructor
                        if mtype.mclass.name != "Pointer" then return
 
                        v = new_visitor
                        if mtype.mclass.name != "Pointer" then return
 
                        v = new_visitor
@@ -751,7 +916,8 @@ class SeparateCompiler
                        else
                                var res = v.new_named_var(mtype, "self")
                                res.is_exact = true
                        else
                                var res = v.new_named_var(mtype, "self")
                                res.is_exact = true
-                               v.add("{res} = nit_alloc(sizeof(struct instance_{mtype.c_name}));")
+                               alloc = v.nit_alloc("sizeof(struct instance_{mtype.c_name})", mclass.full_name)
+                               v.add("{res} = {alloc};")
                                v.add("{res}->type = type;")
                                hardening_live_type(v, "type")
                                v.require_declaration("class_{c_name}")
                                v.add("{res}->type = type;")
                                hardening_live_type(v, "type")
                                v.require_declaration("class_{c_name}")
@@ -778,7 +944,8 @@ class SeparateCompiler
                        var res = v.get_name("self")
                        v.add_decl("struct instance_{c_name} *{res};")
                        var mtype_elt = mtype.arguments.first
                        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}));")
+                       var alloc = v.nit_alloc("sizeof(struct instance_{c_name}) + length*sizeof({mtype_elt.ctype})", mclass.full_name)
+                       v.add("{res} = {alloc};")
                        v.add("{res}->type = type;")
                        hardening_live_type(v, "type")
                        v.require_declaration("class_{c_name}")
                        v.add("{res}->type = type;")
                        hardening_live_type(v, "type")
                        v.require_declaration("class_{c_name}")
@@ -787,21 +954,45 @@ class SeparateCompiler
                        v.add("return (val*){res};")
                        v.add("\}")
                        return
                        v.add("return (val*){res};")
                        v.add("\}")
                        return
-               else if mtype.mclass.kind == extern_kind and mtype.mclass.name != "NativeString" then
-                       # Is an extern class (other than Pointer and NativeString)
-                       # Pointer is caught in a previous `if`, and NativeString is internal
+               else if mclass.name == "RoutineRef" then
+                       self.header.add_decl("struct instance_{c_name} \{")
+                       self.header.add_decl("const struct type *type;")
+                       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, const struct type* type);")
+                       v.add_decl("/* allocate {mtype} */")
+                       v.add_decl("{mtype.ctype} NEW_{c_name}(val* recv, nitmethod_t method, const struct class* class, const struct type* type)\{")
+                       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}->type = type;")
+                       hardening_live_type(v, "type")
+                       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
+                       # Is an extern class (other than Pointer and CString)
+                       # Pointer is caught in a previous `if`, and CString is internal
 
                        var pointer_type = mainmodule.pointer_type
 
                        self.provide_declaration("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}(const struct type* type);")
 
                        var pointer_type = mainmodule.pointer_type
 
                        self.provide_declaration("NEW_{c_name}", "{mtype.ctype} NEW_{c_name}(const struct type* type);")
-                       v.add_decl("/* allocate {mtype} */")
+                       v.add_decl("/* allocate extern {mtype} */")
                        v.add_decl("{mtype.ctype} NEW_{c_name}(const struct type* type) \{")
                        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_decl("{mtype.ctype} NEW_{c_name}(const struct type* type) \{")
                        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}));")
+                               var alloc = v.nit_alloc("sizeof(struct instance_{pointer_type.c_name})", mclass.full_name)
+                               v.add("{res} = {alloc};")
                                v.add("{res}->type = type;")
                                hardening_live_type(v, "type")
                                v.require_declaration("class_{c_name}")
                                v.add("{res}->type = type;")
                                hardening_live_type(v, "type")
                                v.require_declaration("class_{c_name}")
@@ -822,18 +1013,87 @@ class SeparateCompiler
                else
                        var res = v.new_named_var(mtype, "self")
                        res.is_exact = true
                else
                        var res = v.new_named_var(mtype, "self")
                        res.is_exact = true
-                       v.add("{res} = nit_alloc(sizeof(struct instance) + {attrs.length}*sizeof(nitattribute_t));")
+                       var attrs = self.attr_tables.get_or_null(mclass)
+                       if attrs == null then
+                               var alloc = v.nit_alloc("sizeof(struct instance)", mclass.full_name)
+                               v.add("{res} = {alloc};")
+                       else
+                               var alloc = v.nit_alloc("sizeof(struct instance) + {attrs.length}*sizeof(nitattribute_t)", mclass.full_name)
+                               v.add("{res} = {alloc};")
+                       end
+                       if modelbuilder.toolcontext.opt_trace.value then
+                               v.add("tracepoint(Nit_Compiler, Object_Instance,\"{mtype}\", (uintptr_t)self);")
+                               v.add("GC_register_finalizer(self, object_destroy_callback, NULL, NULL, NULL);")
+                       end
                        v.add("{res}->type = type;")
                        hardening_live_type(v, "type")
                        v.require_declaration("class_{c_name}")
                        v.add("{res}->class = &class_{c_name};")
                        v.add("{res}->type = type;")
                        hardening_live_type(v, "type")
                        v.require_declaration("class_{c_name}")
                        v.add("{res}->class = &class_{c_name};")
-                       self.generate_init_attr(v, res, mtype)
-                       v.set_finalizer res
+                       if attrs != null then
+                               self.generate_init_attr(v, res, mtype)
+                               v.set_finalizer res
+                       end
                        v.add("return {res};")
                end
                v.add("\}")
        end
 
                        v.add("return {res};")
                end
                v.add("\}")
        end
 
+       # Compile structures used to map tagged primitive values to their classes and types.
+       # This method also determines which class will be tagged.
+       fun compile_class_infos
+       do
+               if modelbuilder.toolcontext.opt_no_tag_primitives.value then return
+
+               # Note: if you change the tagging scheme, do not forget to update
+               # `autobox` and `extract_tag`
+               var class_info = new Array[nullable MClass].filled_with(null, 4)
+               for t in box_kinds.keys do
+                       # Note: a same class can be associated to multiple slots if one want to
+                       # use some Huffman coding.
+                       if t.name == "Int" then
+                               class_info[1] = t
+                               t.mclass_type.tag_value = 1
+                       else if t.name == "Char" then
+                               class_info[2] = t
+                               t.mclass_type.tag_value = 2
+                       else if t.name == "Bool" then
+                               class_info[3] = t
+                               t.mclass_type.tag_value = 3
+                       else
+                               continue
+                       end
+                       t.mclass_type.is_tagged = true
+               end
+
+               # Compile the table for classes. The tag is used as an index
+               var v = self.new_visitor
+               v.add_decl "const struct class *class_info[4] = \{"
+               for t in class_info do
+                       if t == null then
+                               v.add_decl("NULL,")
+                       else
+                               var s = "class_{t.c_name}"
+                               v.require_declaration(s)
+                               v.add_decl("&{s},")
+                       end
+               end
+               v.add_decl("\};")
+
+               # Compile the table for types. The tag is used as an index
+               v.add_decl "const struct type *type_info[4] = \{"
+               for t in class_info do
+                       if t == null then
+                               v.add_decl("NULL,")
+                       else
+                               var s = "type_{t.c_name}"
+                               undead_types.add(t.mclass_type)
+                               v.require_declaration(s)
+                               v.add_decl("&{s},")
+                       end
+               end
+               v.add_decl("\};")
+       end
+
        # Add a dynamic test to ensure that the type referenced by `t` is a live type
        fun hardening_live_type(v: VISITOR, t: String)
        do
        # Add a dynamic test to ensure that the type referenced by `t` is a live type
        fun hardening_live_type(v: VISITOR, t: String)
        do
@@ -841,8 +1101,8 @@ class SeparateCompiler
                v.add("if({t} == NULL) \{")
                v.add_abort("type null")
                v.add("\}")
                v.add("if({t} == NULL) \{")
                v.add_abort("type null")
                v.add("\}")
-               v.add("if({t}->table_size == 0) \{")
-               v.add("PRINT_ERROR(\"Insantiation of a dead type: %s\\n\", {t}->name);")
+               v.add("if({t}->table_size < 0) \{")
+               v.add("PRINT_ERROR(\"Instantiation of a dead type: %s\\n\", {t}->name);")
                v.add_abort("type dead")
                v.add("\}")
        end
                v.add_abort("type dead")
                v.add("\}")
        end
@@ -854,7 +1114,7 @@ class SeparateCompiler
        private var type_tables: Map[MType, Array[nullable MType]] = new HashMap[MType, Array[nullable MType]]
        private var resolution_tables: Map[MClassType, Array[nullable MType]] = new HashMap[MClassType, Array[nullable MType]]
        protected var method_tables: Map[MClass, Array[nullable MPropDef]] = new HashMap[MClass, Array[nullable MPropDef]]
        private var type_tables: Map[MType, Array[nullable MType]] = new HashMap[MType, Array[nullable MType]]
        private var resolution_tables: Map[MClassType, Array[nullable MType]] = new HashMap[MClassType, Array[nullable MType]]
        protected var method_tables: Map[MClass, Array[nullable MPropDef]] = new HashMap[MClass, Array[nullable MPropDef]]
-       protected var attr_tables: Map[MClass, Array[nullable MPropDef]] = new HashMap[MClass, Array[nullable MPropDef]]
+       protected var attr_tables: Map[MClass, Array[nullable MProperty]] = new HashMap[MClass, Array[nullable MProperty]]
 
        redef fun display_stats
        do
 
        redef fun display_stats
        do
@@ -963,8 +1223,9 @@ class SeparateCompilerVisitor
                        args.first = self.autobox(args.first, m.mclassdef.mclass.mclass_type)
                end
                for i in [0..msignature.arity[ do
                        args.first = self.autobox(args.first, m.mclassdef.mclass.mclass_type)
                end
                for i in [0..msignature.arity[ do
-                       var t = msignature.mparameters[i].mtype
-                       if i == msignature.vararg_rank then
+                       var mp = msignature.mparameters[i]
+                       var t = mp.mtype
+                       if mp.is_vararg then
                                t = args[i+1].mtype
                        end
                        args[i+1] = self.autobox(args[i+1], t)
                                t = args[i+1].mtype
                        end
                        args[i+1] = self.autobox(args[i+1], t)
@@ -978,8 +1239,9 @@ class SeparateCompilerVisitor
                        args.first = self.unbox_extern(args.first, m.mclassdef.mclass.mclass_type)
                end
                for i in [0..msignature.arity[ do
                        args.first = self.unbox_extern(args.first, m.mclassdef.mclass.mclass_type)
                end
                for i in [0..msignature.arity[ do
-                       var t = msignature.mparameters[i].mtype
-                       if i == msignature.vararg_rank then
+                       var mp = msignature.mparameters[i]
+                       var t = mp.mtype
+                       if mp.is_vararg then
                                t = args[i+1].mtype
                        end
                        if m.is_extern then args[i+1] = self.unbox_extern(args[i+1], t)
                                t = args[i+1].mtype
                        end
                        if m.is_extern then args[i+1] = self.unbox_extern(args[i+1], t)
@@ -990,21 +1252,45 @@ class SeparateCompilerVisitor
        do
                if value.mtype == mtype then
                        return value
        do
                if value.mtype == mtype then
                        return value
-               else if value.mtype.ctype == "val*" and mtype.ctype == "val*" then
+               else if not value.mtype.is_c_primitive and not mtype.is_c_primitive then
                        return value
                        return value
-               else if value.mtype.ctype == "val*" then
+               else if not value.mtype.is_c_primitive then
+                       if mtype.is_tagged then
+                               if mtype.name == "Int" then
+                                       return self.new_expr("(long)({value})>>2", mtype)
+                               else if mtype.name == "Char" then
+                                       return self.new_expr("(uint32_t)((long)({value})>>2)", mtype)
+                               else if mtype.name == "Bool" then
+                                       return self.new_expr("(short int)((long)({value})>>2)", mtype)
+                               else
+                                       abort
+                               end
+                       end
                        return self.new_expr("((struct instance_{mtype.c_name}*){value})->value; /* autounbox from {value.mtype} to {mtype} */", mtype)
                        return self.new_expr("((struct instance_{mtype.c_name}*){value})->value; /* autounbox from {value.mtype} to {mtype} */", mtype)
-               else if mtype.ctype == "val*" then
+               else if not mtype.is_c_primitive then
+                       assert value.mtype == value.mcasttype
+                       if value.mtype.is_tagged then
+                               var res
+                               if value.mtype.name == "Int" then
+                                       res = self.new_expr("(val*)({value}<<2|1)", mtype)
+                               else if value.mtype.name == "Char" then
+                                       res = self.new_expr("(val*)((long)({value})<<2|2)", mtype)
+                               else if value.mtype.name == "Bool" then
+                                       res = self.new_expr("(val*)((long)({value})<<2|3)", mtype)
+                               else
+                                       abort
+                               end
+                               # Do not loose type info
+                               res.mcasttype = value.mcasttype
+                               return res
+                       end
                        var valtype = value.mtype.as(MClassType)
                        var valtype = value.mtype.as(MClassType)
-                       if mtype isa MClassType and mtype.mclass.kind == extern_kind and mtype.mclass.name != "NativeString" then
+                       if mtype isa MClassType and mtype.mclass.kind == extern_kind and mtype.mclass.name != "CString" then
                                valtype = compiler.mainmodule.pointer_type
                        end
                        var res = self.new_var(mtype)
                                valtype = compiler.mainmodule.pointer_type
                        end
                        var res = self.new_var(mtype)
-                       if compiler.runtime_type_analysis != null and 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
+                       # Do not loose type info
+                       res.mcasttype = value.mcasttype
                        self.require_declaration("BOX_{valtype.c_name}")
                        self.add("{res} = BOX_{valtype.c_name}({value}); /* autobox from {value.mtype} to {mtype} */")
                        return res
                        self.require_declaration("BOX_{valtype.c_name}")
                        self.add("{res} = BOX_{valtype.c_name}({value}); /* autobox from {value.mtype} to {mtype} */")
                        return res
@@ -1016,7 +1302,7 @@ class SeparateCompilerVisitor
                        # Bad things will appen!
                        var res = self.new_var(mtype)
                        self.add("/* {res} left unintialized (cannot convert {value.mtype} to {mtype}) */")
                        # 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);")
+                       self.add("PRINT_ERROR(\"Cast error: Cannot cast %s to %s.\\n\", \"{value.mtype}\", \"{mtype}\"); fatal_exit(1);")
                        return res
                end
        end
                        return res
                end
        end
@@ -1024,7 +1310,7 @@ class SeparateCompilerVisitor
        redef fun unbox_extern(value, mtype)
        do
                if mtype isa MClassType and mtype.mclass.kind == extern_kind and
        redef fun unbox_extern(value, mtype)
        do
                if mtype isa MClassType and mtype.mclass.kind == extern_kind and
-                  mtype.mclass.name != "NativeString" then
+                  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} */"
                        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} */"
@@ -1037,14 +1323,10 @@ class SeparateCompilerVisitor
        redef fun box_extern(value, mtype)
        do
                if mtype isa MClassType and mtype.mclass.kind == extern_kind and
        redef fun box_extern(value, mtype)
        do
                if mtype isa MClassType and mtype.mclass.kind == extern_kind and
-                  mtype.mclass.name != "NativeString" then
+                  mtype.mclass.name != "CString" then
                        var valtype = compiler.mainmodule.pointer_type
                        var res = self.new_var(mtype)
                        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\"); show_backtrace(1);")
-                               return res
-                       end
+                       compiler.undead_types.add(mtype)
                        self.require_declaration("BOX_{valtype.c_name}")
                        self.add("{res} = BOX_{valtype.c_name}({value}); /* boxing {value.mtype} */")
                        self.require_declaration("type_{mtype.c_name}")
                        self.require_declaration("BOX_{valtype.c_name}")
                        self.add("{res} = BOX_{valtype.c_name}({value}); /* boxing {value.mtype} */")
                        self.require_declaration("type_{mtype.c_name}")
@@ -1057,11 +1339,42 @@ class SeparateCompilerVisitor
                end
        end
 
                end
        end
 
-       # Return a C expression returning the runtime type structure of the value
-       # The point of the method is to works also with primitives types.
+       # Returns a C expression containing the tag of the value as a long.
+       #
+       # If the C expression is evaluated to 0, it means there is no tag.
+       # Thus the expression can be used as a condition.
+       fun extract_tag(value: RuntimeVariable): String
+       do
+               assert not value.mtype.is_c_primitive
+               return "((long){value}&3)" # Get the two low bits
+       end
+
+       # Returns a C expression of the runtime class structure of the value.
+       # The point of the method is to work also with primitive types.
+       fun class_info(value: RuntimeVariable): String
+       do
+               if not value.mtype.is_c_primitive then
+                       if can_be_primitive(value) and not compiler.modelbuilder.toolcontext.opt_no_tag_primitives.value then
+                               var tag = extract_tag(value)
+                               return "({tag}?class_info[{tag}]:{value}->class)"
+                       end
+                       return "{value}->class"
+               else
+                       compiler.undead_types.add(value.mtype)
+                       self.require_declaration("class_{value.mtype.c_name}")
+                       return "(&class_{value.mtype.c_name})"
+               end
+       end
+
+       # Returns a C expression of the runtime type structure of the value.
+       # The point of the method is to work also with primitive types.
        fun type_info(value: RuntimeVariable): String
        do
        fun type_info(value: RuntimeVariable): String
        do
-               if value.mtype.ctype == "val*" then
+               if not value.mtype.is_c_primitive then
+                       if can_be_primitive(value) and not compiler.modelbuilder.toolcontext.opt_no_tag_primitives.value then
+                               var tag = extract_tag(value)
+                               return "({tag}?type_info[{tag}]:{value}->type)"
+                       end
                        return "{value}->type"
                else
                        compiler.undead_types.add(value.mtype)
                        return "{value}->type"
                else
                        compiler.undead_types.add(value.mtype)
@@ -1073,28 +1386,40 @@ class SeparateCompilerVisitor
        redef fun compile_callsite(callsite, args)
        do
                var rta = compiler.runtime_type_analysis
        redef fun compile_callsite(callsite, args)
        do
                var rta = compiler.runtime_type_analysis
-               var mmethod = callsite.mproperty
                # TODO: Inlining of new-style constructors with initializers
                if compiler.modelbuilder.toolcontext.opt_direct_call_monomorph.value and rta != null and callsite.mpropdef.initializers.is_empty then
                        var tgs = rta.live_targets(callsite)
                        if tgs.length == 1 then
                # TODO: Inlining of new-style constructors with initializers
                if compiler.modelbuilder.toolcontext.opt_direct_call_monomorph.value and rta != null and callsite.mpropdef.initializers.is_empty then
                        var tgs = rta.live_targets(callsite)
                        if tgs.length == 1 then
-                               # DIRECT CALL
-                               var res0 = before_send(mmethod, args)
-                               var res = call(tgs.first, tgs.first.mclassdef.bound_mtype, args)
-                               if res0 != null then
-                                       assert res != null
-                                       self.assign(res0, res)
-                                       res = res0
-                               end
-                               add("\}") # close the before_send
-                               return res
+                               return direct_call(tgs.first, args)
                        end
                end
                        end
                end
+               # Shortcut intern methods as they are not usually redefinable
+               if callsite.mpropdef.is_intern and callsite.mproperty.name != "object_id" then
+                       # `object_id` is the only redefined intern method, so it can not be directly called.
+                       # TODO find a less ugly approach?
+                       return direct_call(callsite.mpropdef, args)
+               end
                return super
        end
                return super
        end
+
+       # Fully and directly call a mpropdef
+       #
+       # This method is used by `compile_callsite`
+       private fun direct_call(mpropdef: MMethodDef, args: Array[RuntimeVariable]): nullable RuntimeVariable
+       do
+               var res0 = before_send(mpropdef.mproperty, args)
+               var res = call(mpropdef, mpropdef.mclassdef.bound_mtype, args)
+               if res0 != null then
+                       assert res != null
+                       self.assign(res0, res)
+                       res = res0
+               end
+               add("\}") # close the before_send
+               return res
+       end
        redef fun send(mmethod, arguments)
        do
        redef fun send(mmethod, arguments)
        do
-               if arguments.first.mcasttype.ctype != "val*" then
+               if arguments.first.mcasttype.is_c_primitive then
                        # In order to shortcut the primitive, we need to find the most specific method
                        # Howverr, because of performance (no flattening), we always work on the realmainmodule
                        var m = self.compiler.mainmodule
                        # In order to shortcut the primitive, we need to find the most specific method
                        # Howverr, because of performance (no flattening), we always work on the realmainmodule
                        var m = self.compiler.mainmodule
@@ -1104,7 +1429,7 @@ class SeparateCompilerVisitor
                        return res
                end
 
                        return res
                end
 
-               return table_send(mmethod, arguments, mmethod.const_color)
+               return table_send(mmethod, arguments, mmethod)
        end
 
        # Handle common special cases before doing the effective method invocation
        end
 
        # Handle common special cases before doing the effective method invocation
@@ -1123,8 +1448,7 @@ class SeparateCompilerVisitor
                var res: nullable RuntimeVariable = null
                var recv = arguments.first
                var consider_null = not self.compiler.modelbuilder.toolcontext.opt_no_check_null.value or mmethod.name == "==" or mmethod.name == "!="
                var res: nullable RuntimeVariable = null
                var recv = arguments.first
                var consider_null = not self.compiler.modelbuilder.toolcontext.opt_no_check_null.value or mmethod.name == "==" or mmethod.name == "!="
-               var maybenull = (recv.mcasttype isa MNullableType or recv.mcasttype isa MNullType) and consider_null
-               if maybenull then
+               if maybe_null(recv) and consider_null then
                        self.add("if ({recv} == NULL) \{")
                        if mmethod.name == "==" or mmethod.name == "is_same_instance" then
                                res = self.new_var(bool_type)
                        self.add("if ({recv} == NULL) \{")
                        if mmethod.name == "==" or mmethod.name == "is_same_instance" then
                                res = self.new_var(bool_type)
@@ -1170,19 +1494,20 @@ class SeparateCompilerVisitor
                return res
        end
 
                return res
        end
 
-       private fun table_send(mmethod: MMethod, arguments: Array[RuntimeVariable], const_color: String): nullable RuntimeVariable
+       private fun table_send(mmethod: MMethod, arguments: Array[RuntimeVariable], mentity: MEntity): nullable RuntimeVariable
        do
                compiler.modelbuilder.nb_invok_by_tables += 1
                if compiler.modelbuilder.toolcontext.opt_invocation_metrics.value then add("count_invoke_by_tables++;")
 
                assert arguments.length == mmethod.intro.msignature.arity + 1 else debug("Invalid arity for {mmethod}. {arguments.length} arguments given.")
        do
                compiler.modelbuilder.nb_invok_by_tables += 1
                if compiler.modelbuilder.toolcontext.opt_invocation_metrics.value then add("count_invoke_by_tables++;")
 
                assert arguments.length == mmethod.intro.msignature.arity + 1 else debug("Invalid arity for {mmethod}. {arguments.length} arguments given.")
-               var recv = arguments.first
 
                var res0 = before_send(mmethod, arguments)
 
                var runtime_function = mmethod.intro.virtual_runtime_function
                var msignature = runtime_function.called_signature
 
 
                var res0 = before_send(mmethod, arguments)
 
                var runtime_function = mmethod.intro.virtual_runtime_function
                var msignature = runtime_function.called_signature
 
+               adapt_signature(mmethod.intro, arguments)
+
                var res: nullable RuntimeVariable
                var ret = msignature.return_mtype
                if ret == null then
                var res: nullable RuntimeVariable
                var ret = msignature.return_mtype
                if ret == null then
@@ -1191,26 +1516,44 @@ class SeparateCompilerVisitor
                        res = self.new_var(ret)
                end
 
                        res = self.new_var(ret)
                end
 
-               var ss = new FlatBuffer
-
-               ss.append("{recv}")
-               for i in [0..msignature.arity[ do
-                       var a = arguments[i+1]
-                       var t = msignature.mparameters[i].mtype
-                       if i == msignature.vararg_rank then
-                               t = arguments[i+1].mcasttype
-                       end
-                       a = self.autobox(a, t)
-                       ss.append(", {a}")
-               end
-
-               self.require_declaration(const_color)
-               var call = "(({runtime_function.c_ret} (*){runtime_function.c_sig})({arguments.first}->class->vft[{const_color}]))({ss}) /* {mmethod} on {arguments.first.inspect}*/"
+               var ss = arguments.join(", ")
 
 
+               var const_color = mentity.const_color
+               var ress
                if res != null then
                if res != null then
-                       self.add("{res} = {call};")
+                       ress = "{res} = "
+               else
+                       ress = ""
+               end
+               if mentity isa MMethod and compiler.modelbuilder.toolcontext.opt_direct_call_monomorph0.value then
+                       # opt_direct_call_monomorph0 is used to compare the efficiency of the alternative lookup implementation, ceteris paribus.
+                       # The difference with the non-zero option is that the monomorphism is looked-at on the mmethod level and not at the callsite level.
+                       # TODO: remove this mess and use per callsite service to detect monomorphism in a single place.
+                       var md = compiler.is_monomorphic(mentity)
+                       if md != null then
+                               var callsym = md.virtual_runtime_function.c_name
+                               self.require_declaration(callsym)
+                               self.add "{ress}{callsym}({ss}); /* {mmethod} on {arguments.first.inspect}*/"
+                       else
+                               self.require_declaration(const_color)
+                               self.add "{ress}(({runtime_function.c_funptrtype})({class_info(arguments.first)}->vft[{const_color}]))({ss}); /* {mmethod} on {arguments.first.inspect}*/"
+                       end
+               else if mentity isa MMethod and compiler.modelbuilder.toolcontext.opt_guard_call.value then
+                       var callsym = "CALL_" + const_color
+                       self.require_declaration(callsym)
+                       self.add "if (!{callsym}) \{"
+                       self.require_declaration(const_color)
+                       self.add "{ress}(({runtime_function.c_funptrtype})({class_info(arguments.first)}->vft[{const_color}]))({ss}); /* {mmethod} on {arguments.first.inspect}*/"
+                       self.add "\} else \{"
+                       self.add "{ress}{callsym}({ss}); /* {mmethod} on {arguments.first.inspect}*/"
+                       self.add "\}"
+               else if mentity isa MMethod and compiler.modelbuilder.toolcontext.opt_trampoline_call.value then
+                       var callsym = "CALL_" + const_color
+                       self.require_declaration(callsym)
+                       self.add "{ress}{callsym}({ss}); /* {mmethod} on {arguments.first.inspect}*/"
                else
                else
-                       self.add("{call};")
+                       self.require_declaration(const_color)
+                       self.add "{ress}(({runtime_function.c_funptrtype})({class_info(arguments.first)}->vft[{const_color}]))({ss}); /* {mmethod} on {arguments.first.inspect}*/"
                end
 
                if res0 != null then
                end
 
                if res0 != null then
@@ -1272,7 +1615,7 @@ class SeparateCompilerVisitor
 
        redef fun supercall(m: MMethodDef, recvtype: MClassType, arguments: Array[RuntimeVariable]): nullable RuntimeVariable
        do
 
        redef fun supercall(m: MMethodDef, recvtype: MClassType, arguments: Array[RuntimeVariable]): nullable RuntimeVariable
        do
-               if arguments.first.mcasttype.ctype != "val*" then
+               if arguments.first.mcasttype.is_c_primitive then
                        # In order to shortcut the primitive, we need to find the most specific method
                        # However, because of performance (no flattening), we always work on the realmainmodule
                        var main = self.compiler.mainmodule
                        # In order to shortcut the primitive, we need to find the most specific method
                        # However, because of performance (no flattening), we always work on the realmainmodule
                        var main = self.compiler.mainmodule
@@ -1281,7 +1624,7 @@ class SeparateCompilerVisitor
                        self.compiler.mainmodule = main
                        return res
                end
                        self.compiler.mainmodule = main
                        return res
                end
-               return table_send(m.mproperty, arguments, m.const_color)
+               return table_send(m.mproperty, arguments, m)
        end
 
        redef fun vararg_instance(mpropdef, recv, varargs, elttype)
        end
 
        redef fun vararg_instance(mpropdef, recv, varargs, elttype)
@@ -1323,7 +1666,7 @@ class SeparateCompilerVisitor
                        self.add("{res} = {recv}->attrs[{a.const_color}] != NULL; /* {a} on {recv.inspect}*/")
                else
 
                        self.add("{res} = {recv}->attrs[{a.const_color}] != NULL; /* {a} on {recv.inspect}*/")
                else
 
-                       if mtype.ctype == "val*" then
+                       if not mtype.is_c_primitive and not mtype.is_tagged then
                                self.add("{res} = {recv}->attrs[{a.const_color}].val != NULL; /* {a} on {recv.inspect} */")
                        else
                                self.add("{res} = 1; /* NOT YET IMPLEMENTED: isset of primitives: {a} on {recv.inspect} */")
                                self.add("{res} = {recv}->attrs[{a.const_color}].val != NULL; /* {a} on {recv.inspect} */")
                        else
                                self.add("{res} = 1; /* NOT YET IMPLEMENTED: isset of primitives: {a} on {recv.inspect} */")
@@ -1375,7 +1718,7 @@ class SeparateCompilerVisitor
                        self.add("{res} = {recv}->attrs[{a.const_color}].{ret.ctypename}; /* {a} on {recv.inspect} */")
 
                        # Check for Uninitialized attribute
                        self.add("{res} = {recv}->attrs[{a.const_color}].{ret.ctypename}; /* {a} on {recv.inspect} */")
 
                        # Check for Uninitialized attribute
-                       if ret.ctype == "val*" and not ret isa MNullableType and not self.compiler.modelbuilder.toolcontext.opt_no_check_attr_isset.value then
+                       if not ret.is_c_primitive and not ret isa MNullableType and not self.compiler.modelbuilder.toolcontext.opt_no_check_attr_isset.value then
                                self.add("if (unlikely({res} == NULL)) \{")
                                self.add_abort("Uninitialized attribute {a.name}")
                                self.add("\}")
                                self.add("if (unlikely({res} == NULL)) \{")
                                self.add_abort("Uninitialized attribute {a.name}")
                                self.add("\}")
@@ -1404,7 +1747,11 @@ class SeparateCompilerVisitor
                self.require_declaration(a.const_color)
                if self.compiler.modelbuilder.toolcontext.opt_no_union_attribute.value then
                        var attr = "{recv}->attrs[{a.const_color}]"
                self.require_declaration(a.const_color)
                if self.compiler.modelbuilder.toolcontext.opt_no_union_attribute.value then
                        var attr = "{recv}->attrs[{a.const_color}]"
-                       if mtype.ctype != "val*" then
+                       if mtype.is_tagged then
+                               # The attribute is not primitive, thus store it as tagged
+                               var tv = autobox(value, compiler.mainmodule.object_type)
+                               self.add("{attr} = {tv}; /* {a} on {recv.inspect} */")
+                       else if mtype.is_c_primitive then
                                assert mtype isa MClassType
                                # The attribute is primitive, thus we store it in a box
                                # The trick is to create the box the first time then resuse the box
                                assert mtype isa MClassType
                                # The attribute is primitive, thus we store it in a box
                                # The trick is to create the box the first time then resuse the box
@@ -1530,7 +1877,7 @@ class SeparateCompilerVisitor
                                self.add("count_type_test_resolved_{tag}++;")
                        end
                else
                                self.add("count_type_test_resolved_{tag}++;")
                        end
                else
-                       self.add("PRINT_ERROR(\"NOT YET IMPLEMENTED: type_test(%s, {mtype}).\\n\", \"{value.inspect}\"); show_backtrace(1);")
+                       self.add("PRINT_ERROR(\"NOT YET IMPLEMENTED: type_test(%s, {mtype}).\\n\", \"{value.inspect}\"); fatal_exit(1);")
                end
 
                # check color is in table
                end
 
                # check color is in table
@@ -1556,23 +1903,23 @@ class SeparateCompilerVisitor
        do
                var res = self.new_var(bool_type)
                # Swap values to be symetric
        do
                var res = self.new_var(bool_type)
                # Swap values to be symetric
-               if value2.mtype.ctype != "val*" and value1.mtype.ctype == "val*" then
+               if value2.mtype.is_c_primitive and not value1.mtype.is_c_primitive then
                        var tmp = value1
                        value1 = value2
                        value2 = tmp
                end
                        var tmp = value1
                        value1 = value2
                        value2 = tmp
                end
-               if value1.mtype.ctype != "val*" then
+               if value1.mtype.is_c_primitive then
                        if value2.mtype == value1.mtype then
                                self.add("{res} = 1; /* is_same_type_test: compatible types {value1.mtype} vs. {value2.mtype} */")
                        if value2.mtype == value1.mtype then
                                self.add("{res} = 1; /* is_same_type_test: compatible types {value1.mtype} vs. {value2.mtype} */")
-                       else if value2.mtype.ctype != "val*" then
+                       else if value2.mtype.is_c_primitive then
                                self.add("{res} = 0; /* is_same_type_test: incompatible types {value1.mtype} vs. {value2.mtype}*/")
                        else
                                var mtype1 = value1.mtype.as(MClassType)
                                self.require_declaration("class_{mtype1.c_name}")
                                self.add("{res} = 0; /* is_same_type_test: incompatible types {value1.mtype} vs. {value2.mtype}*/")
                        else
                                var mtype1 = value1.mtype.as(MClassType)
                                self.require_declaration("class_{mtype1.c_name}")
-                               self.add("{res} = ({value2} != NULL) && ({value2}->class == &class_{mtype1.c_name}); /* is_same_type_test */")
+                               self.add("{res} = ({value2} != NULL) && ({class_info(value2)} == &class_{mtype1.c_name}); /* is_same_type_test */")
                        end
                else
                        end
                else
-                       self.add("{res} = ({value1} == {value2}) || ({value1} != NULL && {value2} != NULL && {value1}->class == {value2}->class); /* is_same_type_test */")
+                       self.add("{res} = ({value1} == {value2}) || ({value1} != NULL && {value2} != NULL && {class_info(value1)} == {class_info(value2)}); /* is_same_type_test */")
                end
                return res
        end
                end
                return res
        end
@@ -1581,10 +1928,10 @@ class SeparateCompilerVisitor
        do
                var res = self.get_name("var_class_name")
                self.add_decl("const char* {res};")
        do
                var res = self.get_name("var_class_name")
                self.add_decl("const char* {res};")
-               if value.mtype.ctype == "val*" then
-                       self.add "{res} = {value} == NULL ? \"null\" : {value}->type->name;"
+               if not value.mtype.is_c_primitive then
+                       self.add "{res} = {value} == NULL ? \"null\" : {type_info(value)}->name;"
                else if value.mtype isa MClassType and value.mtype.as(MClassType).mclass.kind == extern_kind and
                else if value.mtype isa MClassType and value.mtype.as(MClassType).mclass.kind == extern_kind and
-                       value.mtype.as(MClassType).name != "NativeString" then
+                       value.mtype.as(MClassType).name != "CString" then
                        self.add "{res} = \"{value.mtype.as(MClassType).mclass}\";"
                else
                        self.require_declaration("type_{value.mtype.c_name}")
                        self.add "{res} = \"{value.mtype.as(MClassType).mclass}\";"
                else
                        self.require_declaration("type_{value.mtype.c_name}")
@@ -1596,24 +1943,64 @@ class SeparateCompilerVisitor
        redef fun equal_test(value1, value2)
        do
                var res = self.new_var(bool_type)
        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
+               if value2.mtype.is_c_primitive and not value1.mtype.is_c_primitive then
                        var tmp = value1
                        value1 = value2
                        value2 = tmp
                end
                        var tmp = value1
                        value1 = value2
                        value2 = tmp
                end
-               if value1.mtype.ctype != "val*" then
-                       if value2.mtype == value1.mtype then
+               if value1.mtype.is_c_primitive then
+                       var t1 = value1.mtype
+                       assert t1 == value1.mcasttype
+
+                       # Fast case: same C type.
+                       if value2.mtype == t1 then
+                               # Same exact C primitive representation.
                                self.add("{res} = {value1} == {value2};")
                                self.add("{res} = {value1} == {value2};")
-                       else if value2.mtype.ctype != "val*" then
-                               self.add("{res} = 0; /* incompatible types {value1.mtype} vs. {value2.mtype}*/")
+                               return res
+                       end
+
+                       # Complex case: value2 has a different representation
+                       # Thus, it should be checked if `value2` is type-compatible with `value1`
+                       # This compatibility is done statically if possible and dynamically else
+
+                       # Conjunction (ands) of dynamic tests according to the static knowledge
+                       var tests = new Array[String]
+
+                       var t2 = value2.mcasttype
+                       if t2 isa MNullableType then
+                               # The destination type cannot be null
+                               tests.add("({value2} != NULL)")
+                               t2 = t2.mtype
+                       else if t2 isa MNullType then
+                               # `value2` is known to be null, thus incompatible with a primitive
+                               self.add("{res} = 0; /* incompatible types {t1} vs. {t2}*/")
+                               return res
+                       end
+
+                       if t2 == t1 then
+                               # Same type but different representation.
+                       else if t2.is_c_primitive then
+                               # Type of `value2` is a different primitive type, thus incompatible
+                               self.add("{res} = 0; /* incompatible types {t1} vs. {t2}*/")
+                               return res
+                       else if t1.is_tagged then
+                               # To be equal, `value2` should also be correctly tagged
+                               tests.add("({extract_tag(value2)} == {t1.tag_value})")
                        else
                        else
-                               var mtype1 = value1.mtype.as(MClassType)
-                               self.require_declaration("class_{mtype1.c_name}")
-                               self.add("{res} = ({value2} != NULL) && ({value2}->class == &class_{mtype1.c_name});")
-                               self.add("if ({res}) \{")
-                               self.add("{res} = ({self.autobox(value2, value1.mtype)} == {value1});")
-                               self.add("\}")
+                               # To be equal, `value2` should also be boxed with the same class
+                               self.require_declaration("class_{t1.c_name}")
+                               tests.add "({class_info(value2)} == &class_{t1.c_name})"
+                       end
+
+                       # Compare the unboxed `value2` with `value1`
+                       if tests.not_empty then
+                               self.add "if ({tests.join(" && ")}) \{"
+                       end
+                       self.add "{res} = {self.autobox(value2, t1)} == {value1};"
+                       if tests.not_empty then
+                               self.add "\} else {res} = 0;"
                        end
                        end
+
                        return res
                end
                var maybe_null = true
                        return res
                end
                var maybe_null = true
@@ -1635,20 +2022,34 @@ class SeparateCompilerVisitor
 
                var incompatible = false
                var primitive
 
                var incompatible = false
                var primitive
-               if t1.ctype != "val*" then
+               if t1.is_c_primitive then
                        primitive = t1
                        if t1 == t2 then
                                # No need to compare class
                        primitive = t1
                        if t1 == t2 then
                                # No need to compare class
-                       else if t2.ctype != "val*" then
+                       else if t2.is_c_primitive then
                                incompatible = true
                        else if can_be_primitive(value2) then
                                incompatible = true
                        else if can_be_primitive(value2) then
+                               if t1.is_tagged then
+                                       self.add("{res} = {value1} == {value2};")
+                                       return res
+                               end
+                               if not compiler.modelbuilder.toolcontext.opt_no_tag_primitives.value then
+                                       test.add("(!{extract_tag(value2)})")
+                               end
                                test.add("{value1}->class == {value2}->class")
                        else
                                incompatible = true
                        end
                                test.add("{value1}->class == {value2}->class")
                        else
                                incompatible = true
                        end
-               else if t2.ctype != "val*" then
+               else if t2.is_c_primitive then
                        primitive = t2
                        if can_be_primitive(value1) then
                        primitive = t2
                        if can_be_primitive(value1) then
+                               if t2.is_tagged then
+                                       self.add("{res} = {value1} == {value2};")
+                                       return res
+                               end
+                               if not compiler.modelbuilder.toolcontext.opt_no_tag_primitives.value then
+                                       test.add("(!{extract_tag(value1)})")
+                               end
                                test.add("{value1}->class == {value2}->class")
                        else
                                incompatible = true
                                test.add("{value1}->class == {value2}->class")
                        else
                                incompatible = true
@@ -1667,13 +2068,25 @@ class SeparateCompilerVisitor
                        end
                end
                if primitive != null then
                        end
                end
                if primitive != null then
+                       if primitive.is_tagged then
+                               self.add("{res} = {value1} == {value2};")
+                               return res
+                       end
                        test.add("((struct instance_{primitive.c_name}*){value1})->value == ((struct instance_{primitive.c_name}*){value2})->value")
                else if can_be_primitive(value1) and can_be_primitive(value2) then
                        test.add("((struct instance_{primitive.c_name}*){value1})->value == ((struct instance_{primitive.c_name}*){value2})->value")
                else if can_be_primitive(value1) and can_be_primitive(value2) then
+                       if not compiler.modelbuilder.toolcontext.opt_no_tag_primitives.value then
+                               test.add("(!{extract_tag(value1)}) && (!{extract_tag(value2)})")
+                       end
                        test.add("{value1}->class == {value2}->class")
                        var s = new Array[String]
                        for t, v in self.compiler.box_kinds do
                        test.add("{value1}->class == {value2}->class")
                        var s = new Array[String]
                        for t, v in self.compiler.box_kinds do
+                               if t.mclass_type.is_tagged then continue
                                s.add "({value1}->class->box_kind == {v} && ((struct instance_{t.c_name}*){value1})->value == ((struct instance_{t.c_name}*){value2})->value)"
                        end
                                s.add "({value1}->class->box_kind == {v} && ((struct instance_{t.c_name}*){value1})->value == ((struct instance_{t.c_name}*){value2})->value)"
                        end
+                       if s.is_empty then
+                               self.add("{res} = {value1} == {value2};")
+                               return res
+                       end
                        test.add("({s.join(" || ")})")
                else
                        self.add("{res} = {value1} == {value2};")
                        test.add("({s.join(" || ")})")
                else
                        self.add("{res} = {value1} == {value2};")
@@ -1685,22 +2098,16 @@ class SeparateCompilerVisitor
 
        fun can_be_primitive(value: RuntimeVariable): Bool
        do
 
        fun can_be_primitive(value: RuntimeVariable): Bool
        do
-               var t = value.mcasttype.as_notnullable
+               var t = value.mcasttype.undecorate
                if not t isa MClassType then return false
                var k = t.mclass.kind
                if not t isa MClassType then return false
                var k = t.mclass.kind
-               return k == interface_kind or t.ctype != "val*"
-       end
-
-       fun maybe_null(value: RuntimeVariable): Bool
-       do
-               var t = value.mcasttype
-               return t isa MNullableType or t isa MNullType
+               return k == interface_kind or t.is_c_primitive
        end
 
        redef fun array_instance(array, elttype)
        do
        end
 
        redef fun array_instance(array, elttype)
        do
-               var nclass = self.get_class("NativeArray")
-               var arrayclass = self.get_class("Array")
+               var nclass = mmodule.native_array_class
+               var arrayclass = mmodule.array_class
                var arraytype = arrayclass.get_mtype([elttype])
                var res = self.init_instance(arraytype)
                self.add("\{ /* {res} = array_instance Array[{elttype}] */")
                var arraytype = arrayclass.get_mtype([elttype])
                var res = self.init_instance(arraytype)
                self.add("\{ /* {res} = array_instance Array[{elttype}] */")
@@ -1715,52 +2122,191 @@ class SeparateCompilerVisitor
                return res
        end
 
                return res
        end
 
-       redef fun native_array_instance(elttype: MType, length: RuntimeVariable): RuntimeVariable
+       redef fun native_array_instance(elttype, length)
        do
        do
-               var mtype = self.get_class("NativeArray").get_mtype([elttype])
+               var mtype = mmodule.native_array_type(elttype)
                self.require_declaration("NEW_{mtype.mclass.c_name}")
                assert mtype isa MGenericType
                var compiler = self.compiler
                self.require_declaration("NEW_{mtype.mclass.c_name}")
                assert mtype isa MGenericType
                var compiler = self.compiler
+               length = autobox(length, compiler.mainmodule.int_type)
                if mtype.need_anchor then
                        hardening_live_open_type(mtype)
                        link_unresolved_type(self.frame.mpropdef.mclassdef, mtype)
                        var recv = self.frame.arguments.first
                        var recv_type_info = self.type_info(recv)
                        self.require_declaration(mtype.const_color)
                if mtype.need_anchor then
                        hardening_live_open_type(mtype)
                        link_unresolved_type(self.frame.mpropdef.mclassdef, mtype)
                        var recv = self.frame.arguments.first
                        var recv_type_info = self.type_info(recv)
                        self.require_declaration(mtype.const_color)
-                       return self.new_expr("NEW_{mtype.mclass.c_name}({length}, {recv_type_info}->resolution_table->types[{mtype.const_color}])", mtype)
+                       return self.new_expr("NEW_{mtype.mclass.c_name}((int){length}, {recv_type_info}->resolution_table->types[{mtype.const_color}])", mtype)
                end
                compiler.undead_types.add(mtype)
                self.require_declaration("type_{mtype.c_name}")
                end
                compiler.undead_types.add(mtype)
                self.require_declaration("type_{mtype.c_name}")
-               return self.new_expr("NEW_{mtype.mclass.c_name}({length}, &type_{mtype.c_name})", mtype)
+               return self.new_expr("NEW_{mtype.mclass.c_name}((int){length}, &type_{mtype.c_name})", mtype)
        end
 
        redef fun native_array_def(pname, ret_type, arguments)
        do
                var elttype = arguments.first.mtype
        end
 
        redef fun native_array_def(pname, ret_type, arguments)
        do
                var elttype = arguments.first.mtype
-               var nclass = self.get_class("NativeArray")
+               var nclass = mmodule.native_array_class
                var recv = "((struct instance_{nclass.c_name}*){arguments[0]})->values"
                if pname == "[]" then
                var recv = "((struct instance_{nclass.c_name}*){arguments[0]})->values"
                if pname == "[]" then
-                       self.ret(self.new_expr("{recv}[{arguments[1]}]", ret_type.as(not null)))
-                       return
+                       # Because the objects are boxed, return the box to avoid unnecessary (or broken) unboxing/reboxing
+                       var res = self.new_expr("{recv}[{arguments[1]}]", compiler.mainmodule.object_type)
+                       res.mcasttype = ret_type.as(not null)
+                       self.ret(res)
+                       return true
                else if pname == "[]=" then
                        self.add("{recv}[{arguments[1]}]={arguments[2]};")
                else if pname == "[]=" then
                        self.add("{recv}[{arguments[1]}]={arguments[2]};")
-                       return
+                       return true
                else if pname == "length" then
                        self.ret(self.new_expr("((struct instance_{nclass.c_name}*){arguments[0]})->length", ret_type.as(not null)))
                else if pname == "length" then
                        self.ret(self.new_expr("((struct instance_{nclass.c_name}*){arguments[0]})->length", ret_type.as(not null)))
-                       return
+                       return true
                else if pname == "copy_to" then
                        var recv1 = "((struct instance_{nclass.c_name}*){arguments[1]})->values"
                        self.add("memmove({recv1}, {recv}, {arguments[2]}*sizeof({elttype.ctype}));")
                else if pname == "copy_to" then
                        var recv1 = "((struct instance_{nclass.c_name}*){arguments[1]})->values"
                        self.add("memmove({recv1}, {recv}, {arguments[2]}*sizeof({elttype.ctype}));")
-                       return
+                       return true
+               else if pname == "memmove" then
+                       # fun memmove(start: Int, length: Int, dest: NativeArray[E], dest_start: Int) is intern do
+                       var recv1 = "((struct instance_{nclass.c_name}*){arguments[3]})->values"
+                       self.add("memmove({recv1}+{arguments[4]}, {recv}+{arguments[1]}, {arguments[2]}*sizeof({elttype.ctype}));")
+                       return true
                end
                end
+               return false
        end
 
        end
 
-       redef fun calloc_array(ret_type, arguments)
+       redef fun native_array_get(nat, i)
        do
        do
-               var mclass = self.get_class("ArrayCapable")
-               var ft = mclass.mparameters.first
-               var res = self.native_array_instance(ft, arguments[1])
-               self.ret(res)
+               var nclass = mmodule.native_array_class
+               var recv = "((struct instance_{nclass.c_name}*){nat})->values"
+               # Because the objects are boxed, return the box to avoid unnecessary (or broken) unboxing/reboxing
+               var res = self.new_expr("{recv}[{i}]", compiler.mainmodule.object_type)
+               return res
+       end
+
+       redef fun native_array_set(nat, i, val)
+       do
+               var nclass = mmodule.native_array_class
+               var recv = "((struct instance_{nclass.c_name}*){nat})->values"
+               self.add("{recv}[{i}]={val};")
+       end
+
+       redef fun routine_ref_instance(routine_type, recv, callsite)
+       do
+               #debug "ENTER ref_instance"
+               var mmethoddef = callsite.mpropdef
+               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)
+               # If the receiver is exact, then there's no need to make a
+               # polymorph call to the underlying method.
+               thunk_function.polymorph_call_flag = not my_recv.is_exact
+               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
+               var res: RuntimeVariable
+               if routine_type.need_anchor then
+                       hardening_live_open_type(routine_type)
+                       link_unresolved_type(self.frame.mpropdef.mclassdef, routine_type)
+                       var recv2 = self.frame.arguments.first
+                       var recv2_type_info = self.type_info(recv2)
+                       self.require_declaration(routine_type.const_color)
+                       res = self.new_expr("NEW_{base_routine_mclass.c_name}({my_recv}, (nitmethod_t){c_ref}, &class_{routine_mclass.c_name}, {recv2_type_info}->resolution_table->types[{routine_type.const_color}])", routine_type)
+               else
+                       self.require_declaration("type_{routine_type.c_name}")
+                       compiler.undead_types.add(routine_type)
+                       res = self.new_expr("NEW_{base_routine_mclass.c_name}({my_recv}, (nitmethod_t){c_ref}, &class_{routine_mclass.c_name}, &type_{routine_type.c_name})", routine_type)
+               end
+               return res
+       end
+
+       redef fun routine_ref_call(mmethoddef, arguments)
+       do
+               #debug "ENTER ref_call"
+               compiler.modelbuilder.nb_invok_by_tables += 1
+               if compiler.modelbuilder.toolcontext.opt_invocation_metrics.value then add("count_invoke_by_tables++;")
+               var nclasses = mmodule.model.get_mclasses_by_name("RoutineRef").as(not null)
+               var nclass = nclasses.first
+               var runtime_function = mmethoddef.virtual_runtime_function
+
+               # Save the current receiver since adapt_signature will autobox
+               # the routine receiver which is not the underlying receiver.
+               # The underlying receiver has already been adapted in the
+               # `routine_ref_instance` method. Here we just want to adapt the
+               # rest of the signature, but it's easier to pass the wrong
+               # receiver in adapt_signature then discards it with `shift`.
+               #
+               # ~~~~nitish
+               # class A; def toto do print "toto"; end
+               # var a = new A
+               # var f = &a.toto # `a` is the underlying receiver
+               # f.call # here `f` is the routine receiver
+               # ~~~~
+               var routine = arguments.first
+
+               # Retrieve the concrete routine type
+               var original_recv_c = "(((struct instance_{nclass.c_name}*){arguments[0]})->recv)"
+               var nitmethod = "(({runtime_function.c_funptrtype})(((struct instance_{nclass.c_name}*){arguments[0]})->method))"
+               if arguments.length > 1 then
+                       adapt_signature(mmethoddef, arguments)
+               end
+
+               var ret_mtype = runtime_function.called_signature.return_mtype
+
+               if ret_mtype != null then
+                       # `ret` is actually always nullable Object. When invoking
+                       # a callref, we don't have the original callsite information.
+                       # Thus, we need to recompute the return type of the callsite.
+                       ret_mtype = resolve_for(ret_mtype, routine)
+               end
+
+               # remove the routine's receiver
+               arguments.shift
+               var ss = arguments.join(", ")
+               # replace the receiver with the original one
+               if arguments.length > 0 then
+                       ss = "{original_recv_c}, {ss}"
+               else
+                       ss = original_recv_c
+               end
+
+               arguments.unshift routine # put back the routine ref receiver
+               add "/* {mmethoddef.mproperty} on {arguments.first.inspect}*/"
+               var callsite = "{nitmethod}({ss})"
+               if ret_mtype != null then
+                       var subres = new_expr("{callsite}", ret_mtype)
+                       ret(subres)
+               else
+                       add("{callsite};")
+               end
        end
 
        fun link_unresolved_type(mclassdef: MClassDef, mtype: MType) do
        end
 
        fun link_unresolved_type(mclassdef: MClassDef, mtype: MType) do
@@ -1786,6 +2332,43 @@ redef class MMethodDef
                end
                return res
        end
                end
                return res
        end
+
+       # Returns true if the current method definition differ from
+       # its original introduction in terms of receiver type.
+       fun recv_differ_from_intro: Bool
+       do
+               var intromclassdef = mproperty.intro.mclassdef
+               var introrecv = intromclassdef.bound_mtype
+               return self.mclassdef.bound_mtype != introrecv
+       end
+
+       # The C thunk function associated to a mmethoddef. Receives only nullable
+       # Object and cast them to the original mmethoddef signature.
+       fun callref_thunk(recv_mtype: MClassType): SeparateThunkFunction
+       do
+               var res = callref_thunk_cache
+               if res == null then
+                       var object_type = mclassdef.mmodule.object_type
+                       var nullable_object = object_type.as_nullable
+                       var ps = new Array[MParameter]
+
+                       # Replace every argument type by nullable object
+                       for p in msignature.mparameters do
+                               ps.push(new MParameter(p.name, nullable_object, p.is_vararg))
+                       end
+                       var ret: nullable MType = null
+                       if msignature.return_mtype != null then ret = nullable_object
+                       var msignature2 = new MSignature(ps, ret)
+                       var intromclassdef = mproperty.intro.mclassdef
+
+                       res = new SeparateThunkFunction(self, recv_mtype, msignature2, "THUNK_{c_name}", mclassdef.bound_mtype)
+                       res.polymorph_call_flag = true
+                       callref_thunk_cache = res
+               end
+               return res
+       end
+
+       private var callref_thunk_cache: nullable SeparateThunkFunction
        private var separate_runtime_function_cache: nullable SeparateRuntimeFunction
 
        # The C function associated to a mmethoddef, that can be stored into a VFT of a class
        private var separate_runtime_function_cache: nullable SeparateRuntimeFunction
 
        # The C function associated to a mmethoddef, that can be stored into a VFT of a class
@@ -1811,10 +2394,7 @@ redef class MMethodDef
                                self.virtual_runtime_function_cache = res
                                return res
                        end
                                self.virtual_runtime_function_cache = res
                                return res
                        end
-
-                       res = new SeparateRuntimeFunction(self, recv, msignature, "VIRTUAL_{c_name}")
-                       self.virtual_runtime_function_cache = res
-                       res.is_thunk = true
+                       res = new SeparateThunkFunction(self, recv, msignature, "VIRTUAL_{c_name}", mclassdef.bound_mtype)
                end
                return res
        end
                end
                return res
        end
@@ -1851,11 +2431,23 @@ class SeparateRuntimeFunction
        # The name on the compiled method
        redef var build_c_name: String
 
        # The name on the compiled method
        redef var build_c_name: String
 
-       # Statically call the original body instead
-       var is_thunk = false
-
        redef fun to_s do return self.mmethoddef.to_s
 
        redef fun to_s do return self.mmethoddef.to_s
 
+       redef fun msignature
+       do
+               return called_signature
+       end
+
+       redef fun recv_mtype
+       do
+               return called_recv
+       end
+
+       redef fun return_mtype
+       do
+               return called_signature.return_mtype
+       end
+
        # The C return type (something or `void`)
        var c_ret: String is lazy do
                var ret = called_signature.return_mtype
        # The C return type (something or `void`)
        var c_ret: String is lazy do
                var ret = called_signature.return_mtype
@@ -1871,9 +2463,10 @@ class SeparateRuntimeFunction
                var sig = new FlatBuffer
                sig.append("({called_recv.ctype} self")
                for i in [0..called_signature.arity[ do
                var sig = new FlatBuffer
                sig.append("({called_recv.ctype} self")
                for i in [0..called_signature.arity[ do
-                       var mtype = called_signature.mparameters[i].mtype
-                       if i == called_signature.vararg_rank then
-                               mtype = mmethoddef.mclassdef.mmodule.get_primitive_class("Array").get_mtype([mtype])
+                       var mp = called_signature.mparameters[i]
+                       var mtype = mp.mtype
+                       if mp.is_vararg then
+                               mtype = mmethoddef.mclassdef.mmodule.array_type(mtype)
                        end
                        sig.append(", {mtype.ctype} p{i}")
                end
                        end
                        sig.append(", {mtype.ctype} p{i}")
                end
@@ -1881,69 +2474,101 @@ class SeparateRuntimeFunction
                return sig.to_s
        end
 
                return sig.to_s
        end
 
-       redef fun compile_to_c(compiler)
+       # The C type for the function pointer.
+       var c_funptrtype: String is lazy do return "{c_ret}(*){c_sig}"
+
+       redef fun declare_signature(v, sig)
+       do
+               v.compiler.provide_declaration(c_name, "{sig};")
+       end
+
+       redef fun body_to_c(v)
        do
        do
-               var mmethoddef = self.mmethoddef
+               var rta = v.compiler.as(SeparateCompiler).runtime_type_analysis
+               if rta != null and not rta.live_mmodules.has(mmethoddef.mclassdef.mmodule) then
+                       v.add_abort("FATAL: Dead method executed.")
+               else
+                       super
+               end
+       end
 
 
+       redef fun end_compile_to_c(v)
+       do
+               var compiler = v.compiler
+               compiler.names[self.c_name] = "{mmethoddef.full_name} ({mmethoddef.location.file.filename}:{mmethoddef.location.line_start})"
+       end
+
+       redef fun build_frame(v, arguments)
+       do
+               var recv = mmethoddef.mclassdef.bound_mtype
+               return new StaticFrame(v, mmethoddef, recv, arguments)
+       end
+
+       # Compile the trampolines used to implement late-binding.
+       #
+       # See `opt_trampoline_call`.
+       fun compile_trampolines(compiler: SeparateCompiler)
+       do
                var recv = self.mmethoddef.mclassdef.bound_mtype
                var recv = self.mmethoddef.mclassdef.bound_mtype
-               var v = compiler.new_visitor
                var selfvar = new RuntimeVariable("self", called_recv, recv)
                var selfvar = new RuntimeVariable("self", called_recv, recv)
-               var arguments = new Array[RuntimeVariable]
-               var frame = new StaticFrame(v, mmethoddef, recv, arguments)
-               v.frame = frame
-
-               var msignature = called_signature
                var ret = called_signature.return_mtype
                var ret = called_signature.return_mtype
-
-               var sig = new FlatBuffer
-               var comment = new FlatBuffer
-               sig.append(c_ret)
-               sig.append(" ")
-               sig.append(self.c_name)
-               sig.append(c_sig)
-               comment.append("({selfvar}: {selfvar.mtype}")
-               arguments.add(selfvar)
-               for i in [0..msignature.arity[ do
-                       var mtype = msignature.mparameters[i].mtype
-                       if i == msignature.vararg_rank then
-                               mtype = v.get_class("Array").get_mtype([mtype])
+               var arguments = ["self"]
+               for i in [0..called_signature.arity[ do arguments.add "p{i}"
+
+               if mmethoddef.is_intro and not recv.is_c_primitive then
+                       var m = mmethoddef.mproperty
+                       var n2 = "CALL_" + m.const_color
+                       compiler.provide_declaration(n2, "{c_ret} {n2}{c_sig};")
+                       var v2 = compiler.new_visitor
+                       v2.add "{c_ret} {n2}{c_sig} \{"
+                       v2.require_declaration(m.const_color)
+                       var call = "(({c_funptrtype})({v2.class_info(selfvar)}->vft[{m.const_color}]))({arguments.join(", ")});"
+                       if ret != null then
+                               v2.add "return {call}"
+                       else
+                               v2.add call
                        end
                        end
-                       comment.append(", {mtype}")
-                       var argvar = new RuntimeVariable("p{i}", mtype, mtype)
-                       arguments.add(argvar)
-               end
-               comment.append(")")
-               if ret != null then
-                       comment.append(": {ret}")
-               end
-               compiler.provide_declaration(self.c_name, "{sig};")
 
 
-               v.add_decl("/* method {self} for {comment} */")
-               v.add_decl("{sig} \{")
-               if ret != null then
-                       frame.returnvar = v.new_var(ret)
-               end
-               frame.returnlabel = v.get_name("RET_LABEL")
+                       v2.add "\}"
 
 
-               if is_thunk then
-                       var subret = v.call(mmethoddef, recv, arguments)
+               end
+               if mmethoddef.has_supercall and not recv.is_c_primitive then
+                       var m = mmethoddef
+                       var n2 = "CALL_" + m.const_color
+                       compiler.provide_declaration(n2, "{c_ret} {n2}{c_sig};")
+                       var v2 = compiler.new_visitor
+                       v2.add "{c_ret} {n2}{c_sig} \{"
+                       v2.require_declaration(m.const_color)
+                       var call = "(({c_funptrtype})({v2.class_info(selfvar)}->vft[{m.const_color}]))({arguments.join(", ")});"
                        if ret != null then
                        if ret != null then
-                               assert subret != null
-                               v.assign(frame.returnvar.as(not null), subret)
+                               v2.add "return {call}"
+                       else
+                               v2.add call
                        end
                        end
-               else
-                       mmethoddef.compile_inside_to_c(v, arguments)
-               end
 
 
-               v.add("{frame.returnlabel.as(not null)}:;")
-               if ret != null then
-                       v.add("return {frame.returnvar.as(not null)};")
+                       v2.add "\}"
                end
                end
-               v.add("\}")
-               compiler.names[self.c_name] = "{mmethoddef.full_name} ({mmethoddef.location.file.filename}:{mmethoddef.location.line_start})"
        end
 end
 
        end
 end
 
+class SeparateThunkFunction
+       super ThunkFunction
+       super SeparateRuntimeFunction
+       redef var target_recv
+end
+
+redef class MType
+       # Are values of `self` tagged?
+       # If false, it means that the type is not primitive, or is boxed.
+       var is_tagged = false
+
+       # The tag value of the type
+       #
+       # ENSURE `is_tagged == (tag_value > 0)`
+       # ENSURE `not is_tagged == (tag_value == 0)`
+       var tag_value = 0
+end
+
 redef class MEntity
        var const_color: String is lazy do return "COLOR_{c_name}"
 end
 redef class MEntity
        var const_color: String is lazy do return "COLOR_{c_name}"
 end
@@ -1967,3 +2592,14 @@ redef class AMethPropdef
                return super
        end
 end
                return super
        end
 end
+
+redef class AAttrPropdef
+       redef fun init_expr(v, recv)
+       do
+               super
+               if is_lazy and v.compiler.modelbuilder.toolcontext.opt_no_union_attribute.value then
+                       var guard = self.mlazypropdef.mproperty
+                       v.write_attribute(guard, recv, v.bool_instance(false))
+               end
+       end
+end