Updated `tests/syntax_callref.nit`
[nit.git] / src / compiler / separate_compiler.nit
index cf6a516..9c98d07 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
-       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-tag-primitives
+       var opt_no_tag_primitives = new OptionBool("Use only boxes for primitive types", "--no-tag-primitives")
+
        # --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
-       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
@@ -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")
+       # --type-poset
+       var opt_type_poset = new OptionBool("Build a poset of types to create more condensed tables", "--type-poset")
 
        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_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_type_poset)
        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
+               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)
@@ -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
-       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")
@@ -144,6 +168,7 @@ class SeparateCompiler
                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
@@ -156,6 +181,7 @@ class SeparateCompiler
                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
@@ -170,6 +196,15 @@ class SeparateCompiler
                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
@@ -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. */")
+
+               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
@@ -222,10 +262,11 @@ class SeparateCompiler
        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
-                       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
@@ -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
-               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
-
        end
 
        fun compile_color_consts(colors: Map[Object, Int]) do
@@ -258,7 +298,7 @@ class SeparateCompiler
                if m isa MEntity then
                        if modelbuilder.toolcontext.opt_inline_coloring_numbers.value then
                                self.provide_declaration(m.const_color, "#define {m.const_color} {color}")
-                       else if not modelbuilder.toolcontext.opt_colors_are_symbols.value then
+                       else if not modelbuilder.toolcontext.opt_colors_are_symbols.value or not v.compiler.target_platform.supports_linker_script then
                                self.provide_declaration(m.const_color, "extern const int {m.const_color};")
                                v.add("const int {m.const_color} = {color};")
                        else
@@ -276,186 +316,179 @@ class SeparateCompiler
 
        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
 
-               # Layouts
-               var poset = mainmodule.flatten_mclass_hierarchy
-               var mclasses = new HashSet[MClass].from(poset)
-               var colorer = new POSetColorer[MClass]
-               colorer.colorize(poset)
-
-               # The dead methods, still need to provide a dead color symbol
-               var dead_methods = new Array[MMethod]
+               # Class graph
+               var mclasses = mainmodule.flatten_mclass_hierarchy
+               class_conflict_graph = mclasses.to_conflict_graph
 
-               # 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]]
+
+               # 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 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
 
-               # 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
+                               else if p isa MAttribute then
+                                       mattributes[mclass].add p
                                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
-               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)
 
-               # 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)
-       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
-                       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
 
-                       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
-                               var mmethoddef = supercall.lookup_next_definition(mainmodule, mtype)
-                               table[color] = mmethoddef
                        end
 
+                       # Do not need to resolve attributes as only the position is used
+                       attr_tables[mclass] = attr_colorer.build_layout(mclass)
                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
-       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
-               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
-               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]
+
+               # 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
+                       var c = e.undecorate.as(MClassType).mclass
+                       mtypes_by_class[c].add(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
+
+               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)
+               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
@@ -481,29 +514,74 @@ class SeparateCompiler
                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
-               var mtype2unresolved = new HashMap[MClassType, Set[MType]]
+               var mtype2unresolved = new HashMap[MClass, Set[MType]]
                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
-                       mtype2unresolved[mtype] = set
                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)
-               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)
@@ -528,9 +606,10 @@ class SeparateCompiler
                #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]]
-               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]
@@ -554,18 +633,91 @@ class SeparateCompiler
                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 r = pd.separate_runtime_function
                                r.compile_to_c(self)
                                var r2 = pd.virtual_runtime_function
-                               r2.compile_to_c(self)
+                               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
+               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
 
+       # 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
@@ -608,7 +760,7 @@ class SeparateCompiler
 
                # 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*/")
@@ -634,14 +786,15 @@ class SeparateCompiler
                        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
 
-               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};")
@@ -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
+               if mclass.is_broken then return
+
                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 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
-               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("\{")
-                       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 */")
@@ -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
+                                       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)
@@ -714,9 +874,11 @@ class SeparateCompiler
                        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
 
+                       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;")
@@ -724,13 +886,15 @@ class SeparateCompiler
                        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) \{")
-                       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};")
@@ -740,6 +904,7 @@ class SeparateCompiler
                        v.add("return (val*)res;")
                        v.add("\}")
 
+                       # A Pointer class also need its constructor
                        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
-                               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}")
@@ -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
-                       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}")
@@ -787,21 +954,45 @@ class SeparateCompiler
                        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);")
-                       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("{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}")
@@ -822,18 +1013,87 @@ class SeparateCompiler
                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};")
-                       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
 
+       # 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
@@ -841,8 +1101,8 @@ class SeparateCompiler
                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
@@ -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]]
-       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
@@ -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
-                       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)
@@ -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
-                       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)
@@ -990,21 +1252,45 @@ class SeparateCompilerVisitor
        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
-               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)
-               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)
-                       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)
-                       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
@@ -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}) */")
-                       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
@@ -1024,7 +1310,7 @@ class SeparateCompilerVisitor
        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} */"
@@ -1037,14 +1323,10 @@ class SeparateCompilerVisitor
        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)
-                       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}")
@@ -1057,11 +1339,42 @@ class SeparateCompilerVisitor
                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
-               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)
@@ -1073,28 +1386,40 @@ class SeparateCompilerVisitor
        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
-                               # 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
+               # 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
+
+       # 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
-               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
@@ -1104,7 +1429,7 @@ class SeparateCompilerVisitor
                        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
@@ -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 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)
@@ -1170,18 +1494,21 @@ class SeparateCompilerVisitor
                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.")
-               var recv = arguments.first
 
                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 msignature = mmethod.intro.msignature.resolve_for(mmethod.intro.mclassdef.bound_mtype, mmethod.intro.mclassdef.bound_mtype, mmethod.intro.mclassdef.mmodule, true)
                var ret = msignature.return_mtype
                if ret == null then
                        res = null
@@ -1189,32 +1516,44 @@ class SeparateCompilerVisitor
                        res = self.new_var(ret)
                end
 
-               var s = new FlatBuffer
-               var ss = new FlatBuffer
-
-               s.append("val*")
-               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
-                       s.append(", {t.ctype}")
-                       a = self.autobox(a, t)
-                       ss.append(", {a}")
-               end
-
-
-               var r
-               if ret == null then r = "void" else r = ret.ctype
-               self.require_declaration(const_color)
-               var call = "(({r} (*)({s}))({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
-                       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
-                       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
@@ -1245,7 +1584,7 @@ class SeparateCompilerVisitor
                        (compiler.modelbuilder.toolcontext.opt_inline_some_methods.value and mmethoddef.can_inline(self)) then
                        compiler.modelbuilder.nb_invok_by_inline += 1
                        if compiler.modelbuilder.toolcontext.opt_invocation_metrics.value then add("count_invoke_by_inline++;")
-                       var frame = new Frame(self, mmethoddef, recvtype, arguments)
+                       var frame = new StaticFrame(self, mmethoddef, recvtype, arguments)
                        frame.returnlabel = self.get_name("RET_LABEL")
                        frame.returnvar = res
                        var old_frame = self.frame
@@ -1276,7 +1615,7 @@ class SeparateCompilerVisitor
 
        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
@@ -1285,7 +1624,7 @@ class SeparateCompilerVisitor
                        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)
@@ -1295,11 +1634,11 @@ class SeparateCompilerVisitor
                # of the method (ie recv) if the static type is unresolved
                # This is more complex than usual because the unresolved type must not be resolved
                # with the current receiver (ie self).
-               # Therefore to isolate the resolution from self, a local Frame is created.
+               # Therefore to isolate the resolution from self, a local StaticFrame is created.
                # One can see this implementation as an inlined method of the receiver whose only
                # job is to allocate the array
                var old_frame = self.frame
-               var frame = new Frame(self, mpropdef, mpropdef.mclassdef.bound_mtype, [recv])
+               var frame = new StaticFrame(self, mpropdef, mpropdef.mclassdef.bound_mtype, [recv])
                self.frame = frame
                #print "required Array[{elttype}] for recv {recv.inspect}. bound=Array[{self.resolve_for(elttype, recv)}]. selfvar={frame.arguments.first.inspect}"
                var res = self.array_instance(varargs, elttype)
@@ -1327,7 +1666,7 @@ class SeparateCompilerVisitor
                        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} */")
@@ -1379,7 +1718,7 @@ class SeparateCompilerVisitor
                        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("\}")
@@ -1408,7 +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}]"
-                       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
@@ -1534,7 +1877,7 @@ class SeparateCompilerVisitor
                                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
@@ -1560,23 +1903,23 @@ class SeparateCompilerVisitor
        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
-               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} */")
-                       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} = ({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
-                       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
@@ -1585,10 +1928,10 @@ class SeparateCompilerVisitor
        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
-                       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}")
@@ -1600,24 +1943,64 @@ class SeparateCompilerVisitor
        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
-               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};")
-                       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
-                               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
+
                        return res
                end
                var maybe_null = true
@@ -1639,20 +2022,34 @@ class SeparateCompilerVisitor
 
                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
-                       else if t2.ctype != "val*" then
+                       else if t2.is_c_primitive 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
-               else if t2.ctype != "val*" then
+               else if t2.is_c_primitive 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
@@ -1671,13 +2068,25 @@ class SeparateCompilerVisitor
                        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
+                       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
+                               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
+                       if s.is_empty then
+                               self.add("{res} = {value1} == {value2};")
+                               return res
+                       end
                        test.add("({s.join(" || ")})")
                else
                        self.add("{res} = {value1} == {value2};")
@@ -1689,22 +2098,16 @@ class SeparateCompilerVisitor
 
        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
-               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
-               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}] */")
@@ -1719,52 +2122,184 @@ class SeparateCompilerVisitor
                return res
        end
 
-       redef fun native_array_instance(elttype: MType, length: RuntimeVariable): RuntimeVariable
+       redef fun native_array_instance(elttype, length)
        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
+               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)
-                       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}")
-               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
-               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
-                       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]};")
-                       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)))
-                       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}));")
-                       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
+               return false
        end
 
-       redef fun calloc_array(ret_type, arguments)
+       redef fun native_array_get(nat, i)
        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, mmethoddef)
+       do
+               #debug "ENTER ref_instance"
+               var mmethod = mmethoddef.mproperty
+               # routine_mclass is the specialized one, e.g: FunRef1, ProcRef2, etc..
+               var routine_mclass = routine_type.mclass
+
+               var nclasses = mmodule.model.get_mclasses_by_name("RoutineRef").as(not null)
+               var base_routine_mclass = nclasses.first
+
+               # All routine classes use the same `NEW` constructor.
+               # However, they have different declared `class` and `type` value.
+               self.require_declaration("NEW_{base_routine_mclass.c_name}")
+
+               var recv_class_cname = recv.mcasttype.as(MClassType).mclass.c_name
+               var my_recv = recv
+
+               if recv.mtype.is_c_primitive then
+                       my_recv = autobox(recv, mmodule.object_type)
+               end
+               var my_recv_mclass_type = my_recv.mtype.as(MClassType)
+
+               # The class of the concrete Routine must exist (e.g ProcRef0, FunRef0, etc.)
+               self.require_declaration("class_{routine_mclass.c_name}")
+               self.require_declaration("type_{routine_type.c_name}")
+
+               compiler.undead_types.add(routine_type)
+               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
+
+               # Each RoutineRef points to a receiver AND a callref_thunk
+               var res = self.new_expr("NEW_{base_routine_mclass.c_name}({my_recv}, (nitmethod_t){c_ref}, &class_{routine_mclass.c_name}, &type_{routine_type.c_name})", routine_type)
+               #debug "LEAVING ref_instance"
+               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
@@ -1778,176 +2313,253 @@ class SeparateCompilerVisitor
 end
 
 redef class MMethodDef
-       fun separate_runtime_function: AbstractRuntimeFunction
+       # The C function associated to a mmethoddef
+       fun separate_runtime_function: SeparateRuntimeFunction
        do
                var res = self.separate_runtime_function_cache
                if res == null then
-                       res = new SeparateRuntimeFunction(self)
+                       var recv = mclassdef.bound_mtype
+                       var msignature = msignature.resolve_for(recv, recv, mclassdef.mmodule, true)
+                       res = new SeparateRuntimeFunction(self, recv, msignature, c_name)
                        self.separate_runtime_function_cache = res
                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
 
-       fun virtual_runtime_function: AbstractRuntimeFunction
+       # The C function associated to a mmethoddef, that can be stored into a VFT of a class
+       # The first parameter (the reciever) is always typed by val* in order to accept an object value
+       # The C-signature is always compatible with the intro
+       fun virtual_runtime_function: SeparateRuntimeFunction
        do
                var res = self.virtual_runtime_function_cache
                if res == null then
-                       res = new VirtualRuntimeFunction(self)
-                       self.virtual_runtime_function_cache = res
+                       # Because the function is virtual, the signature must match the one of the original class
+                       var intromclassdef = mproperty.intro.mclassdef
+                       var recv = intromclassdef.bound_mtype
+
+                       res = separate_runtime_function
+                       if res.called_recv == recv then
+                               self.virtual_runtime_function_cache = res
+                               return res
+                       end
+
+                       var msignature = mproperty.intro.msignature.resolve_for(recv, recv, intromclassdef.mmodule, true)
+
+                       if recv.ctype == res.called_recv.ctype and msignature.c_equiv(res.called_signature) then
+                               self.virtual_runtime_function_cache = res
+                               return res
+                       end
+                       res = new SeparateThunkFunction(self, recv, msignature, "VIRTUAL_{c_name}", mclassdef.bound_mtype)
                end
                return res
        end
-       private var virtual_runtime_function_cache: nullable VirtualRuntimeFunction
+       private var virtual_runtime_function_cache: nullable SeparateRuntimeFunction
+end
+
+redef class MSignature
+       # Does the C-version of `self` the same than the C-version of `other`?
+       fun c_equiv(other: MSignature): Bool
+       do
+               if self == other then return true
+               if arity != other.arity then return false
+               for i in [0..arity[ do
+                       if mparameters[i].mtype.ctype != other.mparameters[i].mtype.ctype then return false
+               end
+               if return_mtype != other.return_mtype then
+                       if return_mtype == null or other.return_mtype == null then return false
+                       if return_mtype.ctype != other.return_mtype.ctype then return false
+               end
+               return true
+       end
 end
 
 # The C function associated to a methoddef separately compiled
 class SeparateRuntimeFunction
        super AbstractRuntimeFunction
 
-       redef fun build_c_name: String do return "{mmethoddef.c_name}"
+       # The call-side static receiver
+       var called_recv: MType
+
+       # The call-side static signature
+       var called_signature: MSignature
+
+       # The name on the compiled method
+       redef var build_c_name: String
 
        redef fun to_s do return self.mmethoddef.to_s
 
-       redef fun compile_to_c(compiler)
+       redef fun msignature
        do
-               var mmethoddef = self.mmethoddef
+               return called_signature
+       end
 
-               var recv = self.mmethoddef.mclassdef.bound_mtype
-               var v = compiler.new_visitor
-               var selfvar = new RuntimeVariable("self", recv, recv)
-               var arguments = new Array[RuntimeVariable]
-               var frame = new Frame(v, mmethoddef, recv, arguments)
-               v.frame = frame
+       redef fun recv_mtype
+       do
+               return called_recv
+       end
 
-               var msignature = mmethoddef.msignature.resolve_for(mmethoddef.mclassdef.bound_mtype, mmethoddef.mclassdef.bound_mtype, mmethoddef.mclassdef.mmodule, true)
+       redef fun return_mtype
+       do
+               return called_signature.return_mtype
+       end
 
-               var sig = new FlatBuffer
-               var comment = new FlatBuffer
-               var ret = msignature.return_mtype
+       # The C return type (something or `void`)
+       var c_ret: String is lazy do
+               var ret = called_signature.return_mtype
                if ret != null then
-                       sig.append("{ret.ctype} ")
+                       return ret.ctype
                else
-                       sig.append("void ")
+                       return "void"
                end
-               sig.append(self.c_name)
-               sig.append("({selfvar.mtype.ctype} {selfvar}")
-               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])
+       end
+
+       # The C signature (only the parmeter part)
+       var c_sig: String is lazy do
+               var sig = new FlatBuffer
+               sig.append("({called_recv.ctype} self")
+               for i in [0..called_signature.arity[ do
+                       var mp = called_signature.mparameters[i]
+                       var mtype = mp.mtype
+                       if mp.is_vararg then
+                               mtype = mmethoddef.mclassdef.mmodule.array_type(mtype)
                        end
-                       comment.append(", {mtype}")
                        sig.append(", {mtype.ctype} p{i}")
-                       var argvar = new RuntimeVariable("p{i}", mtype, mtype)
-                       arguments.add(argvar)
                end
                sig.append(")")
-               comment.append(")")
-               if ret != null then
-                       comment.append(": {ret}")
-               end
-               compiler.provide_declaration(self.c_name, "{sig};")
+               return sig.to_s
+       end
 
-               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")
+       # The C type for the function pointer.
+       var c_funptrtype: String is lazy do return "{c_ret}(*){c_sig}"
 
-               if recv != arguments.first.mtype then
-                       #print "{self} {recv} {arguments.first}"
-               end
-               mmethoddef.compile_inside_to_c(v, arguments)
+       redef fun declare_signature(v, sig)
+       do
+               v.compiler.provide_declaration(c_name, "{sig};")
+       end
 
-               v.add("{frame.returnlabel.as(not null)}:;")
-               if ret != null then
-                       v.add("return {frame.returnvar.as(not null)};")
+       redef fun body_to_c(v)
+       do
+               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
-               v.add("\}")
-               if not self.c_name.has_substring("VIRTUAL", 0) then compiler.names[self.c_name] = "{mmethoddef.mclassdef.mmodule.name}::{mmethoddef.mclassdef.mclass.name}::{mmethoddef.mproperty.name} ({mmethoddef.location.file.filename}:{mmethoddef.location.line_start})"
        end
-end
 
-# The C function associated to a methoddef on a primitive type, stored into a VFT of a class
-# The first parameter (the reciever) is always typed by val* in order to accept an object value
-class VirtualRuntimeFunction
-       super AbstractRuntimeFunction
-
-       redef fun build_c_name: String do return "VIRTUAL_{mmethoddef.c_name}"
-
-       redef fun to_s do return self.mmethoddef.to_s
+       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 compile_to_c(compiler)
+       redef fun build_frame(v, arguments)
        do
-               var mmethoddef = self.mmethoddef
+               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 v = compiler.new_visitor
-               var selfvar = new RuntimeVariable("self", v.object_type, recv)
-               var arguments = new Array[RuntimeVariable]
-               var frame = new Frame(v, mmethoddef, recv, arguments)
-               v.frame = frame
+               var selfvar = new RuntimeVariable("self", called_recv, recv)
+               var ret = called_signature.return_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
 
-               var sig = new FlatBuffer
-               var comment = new FlatBuffer
+                       v2.add "\}"
 
-               # Because the function is virtual, the signature must match the one of the original class
-               var intromclassdef = self.mmethoddef.mproperty.intro.mclassdef
-               var msignature = mmethoddef.mproperty.intro.msignature.resolve_for(intromclassdef.bound_mtype, intromclassdef.bound_mtype, intromclassdef.mmodule, true)
-               var ret = msignature.return_mtype
-               if ret != null then
-                       sig.append("{ret.ctype} ")
-               else
-                       sig.append("void ")
                end
-               sig.append(self.c_name)
-               sig.append("({selfvar.mtype.ctype} {selfvar}")
-               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])
+               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
+                               v2.add "return {call}"
+                       else
+                               v2.add call
                        end
-                       comment.append(", {mtype}")
-                       sig.append(", {mtype.ctype} p{i}")
-                       var argvar = new RuntimeVariable("p{i}", mtype, mtype)
-                       arguments.add(argvar)
-               end
-               sig.append(")")
-               comment.append(")")
-               if ret != null then
-                       comment.append(": {ret}")
-               end
-               compiler.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)
+                       v2.add "\}"
                end
-               frame.returnlabel = v.get_name("RET_LABEL")
+       end
+end
 
-               var subret = v.call(mmethoddef, recv, arguments)
-               if ret != null then
-                       assert subret != null
-                       v.assign(frame.returnvar.as(not null), subret)
-               end
+class SeparateThunkFunction
+       super ThunkFunction
+       super SeparateRuntimeFunction
+       redef var target_recv
+end
 
-               v.add("{frame.returnlabel.as(not null)}:;")
-               if ret != null then
-                       v.add("return {frame.returnvar.as(not null)};")
-               end
-               v.add("\}")
-               if not self.c_name.has_substring("VIRTUAL", 0) then compiler.names[self.c_name] = "{mmethoddef.mclassdef.mmodule.name}::{mmethoddef.mclassdef.mclass.name}::{mmethoddef.mproperty.name} ({mmethoddef.location.file.filename}--{mmethoddef.location.line_start})"
-       end
+redef class MType
+       # Are values of `self` tagged?
+       # If false, it means that the type is not primitive, or is boxed.
+       var is_tagged = false
 
-       # TODO ?
-       redef fun call(v, arguments) do abort
+       # 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
@@ -1973,3 +2585,14 @@ redef class AMethPropdef
                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