compile: better types checks on virtual type

[nit.git] / src / compiling / table_computation.nit

# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2008 Jean Privat <jean@pryen.org>
# Copyright 2009 Jean-Sebastien Gelinas <calestar@gmail.com>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Compute tables for classes and modules.
package table_computation

import mmloader
import primitive_info
import program

# Something that store color of table elements
class ColorContext
        var _colors: HashMap[TableElt, Int] = new HashMap[TableElt, Int]

        # The color of a table element.
        fun color(e: TableElt): Int
        do
                return _colors[e]
        end

        # Is a table element already colored?
        fun has_color(e: TableElt): Bool
        do
                return _colors.has_key(e)
        end

        # Assign a color to a table element.
        fun color=(e: TableElt, c: Int)
        do
                _colors[e] = c
                var idx = c
                for i in [0..e.length[ do
                        _colors[e.item(i)] = idx
                        idx = idx + 1
                end
        end
end

# All information and results of the global analysis.
class TableInformation
        super ColorContext
        # FIXME: do something better.
        readable writable var _max_class_table_length: Int = 0
end

# A compiled class is a class in a program
class CompiledClass
        super ColorContext
        # The corresponding local class in the main module of the prgram
        readable var _local_class: MMLocalClass

        # The identifier of the class
        readable writable var _id: Int = 0

        # The full class table of the class
        readable var _class_table: Array[nullable TableElt] = new Array[nullable TableElt]

        # The full instance table of the class
        readable var _instance_table: Array[nullable TableElt] = new Array[nullable TableElt]

        # The proper class table part (no superclasses but all refinements)
        readable writable var _class_layout: TableEltComposite = new TableEltComposite(self)

        # The proper instance table part (no superclasses but all refinements)
        readable writable var _instance_layout: TableEltComposite = new TableEltComposite(self)

        init(c: MMLocalClass) do _local_class = c
end

redef class MMConcreteClass
        # The table element of the subtype check
        fun class_color_pos: TableEltClassColor do return _class_color_pos.as(not null)
        var _class_color_pos: nullable TableEltClassColor

        # The proper local class table part (nor superclasses nor refinments)
        readable var _class_layout: Array[TableElt] = new Array[TableElt]

        # The proper local instance table part (nor superclasses nor refinments)
        readable var _instance_layout: Array[TableElt] = new Array[TableElt]

        # Build the local layout of the class and feed the module table
        private fun build_layout_in(module_table: Array[ModuleTableElt])
        do
                var clt = _class_layout
                var ilt = _instance_layout

                if global.intro == self then
                        module_table.add(new TableEltClassId(self))
                        var cpp = new TableEltClassColor(self)
                        _class_color_pos = cpp
                        module_table.add(cpp)
                        clt.add(new TableEltClassInitTable(self))
                end
                for p in local_local_properties do
                        var pg = p.global
                        if pg.intro == p then
                                if p isa MMAttribute then
                                        ilt.add(new TableEltAttr(p))
                                else if p isa MMMethod then
                                        clt.add(new TableEltMeth(p))
                                else if p isa MMTypeProperty then
                                        clt.add(new TableEltVTClassId(p))
                                        clt.add(new TableEltVTClassColor(p))
                                end
                        end
                        if p isa MMMethod and p.need_super then
                                clt.add(new TableEltSuper(p))
                        end
                end

                if not ilt.is_empty then
                        var teg = new ModuleTableEltGroup
                        teg.elements.append(ilt)
                        module_table.add(teg)
                end

                if not clt.is_empty then
                        var teg = new ModuleTableEltGroup
                        teg.elements.append(clt)
                        module_table.add(teg)
                end
        end
end

redef class Program
        # Information about the class tables
        readable var _table_information: TableInformation = new TableInformation

        # Associate global classes to compiled classes
        readable var _compiled_classes: HashMap[MMGlobalClass, CompiledClass] = new HashMap[MMGlobalClass, CompiledClass]

        fun do_table_computation
        do
                tc.info("Building tables",1)
                for m in main_module.mhe.greaters_and_self do
                        tc.info("Building tables for module: {m.name}",2)
                        m.local_analysis
                end

                tc.info("Merging all tables",2)
                do_global_table_analysis
        end

        # Do the complete global analysis
        private fun do_global_table_analysis
        do
                var smallest_classes = new Array[MMLocalClass]
                var global_properties = new HashSet[MMGlobalProperty]
                var ctab = new Array[TableElt]
                var itab = new Array[TableElt]

                ctab.add(new TableEltClassSelfId)
                ctab.add(new TableEltClassObjectSize)
                itab.add(new TableEltVftPointer)
                itab.add(new TableEltObjectId)

                var pclassid = -1
                var classid = 3

                # We have to work on ALL the classes of the module
                var classes = new Array[MMLocalClass]
                for c in main_module.local_classes do classes.add(c)
                classes.sort !cmp(x,y) = x.total_order_compare(y)

                for c in classes do
                        # Associate a CompiledClass to the class
                        var cc = new CompiledClass(c)
                        compiled_classes[c.global] = cc

                        # Assign a unique class identifier
                        # (negative are for primitive classes)
                        var gc = c.global
                        var bm = gc.mmmodule
                        if c.primitive_info != null then
                                cc.id = pclassid
                                pclassid = pclassid - 4
                        else
                                cc.id = classid
                                classid = classid + 4
                        end

                        # Register is the class is a leaf
                        if c.cshe.direct_smallers.is_empty then
                                smallest_classes.add(c)
                        end

                        # Store the colortableelt in the class table pool
                        var bc = c.global.intro
                        assert bc isa MMConcreteClass
                        ctab.add(bc.class_color_pos)
                end

                # Compute core and crown classes for colorization
                var crown_classes = new HashSet[MMLocalClass]
                var core_classes = new HashSet[MMLocalClass]
                for c in smallest_classes do
                        while c.cshe.direct_greaters.length == 1 do
                                c = c.cshe.direct_greaters.first
                        end
                        crown_classes.add(c)
                        core_classes.add_all(c.cshe.greaters_and_self)
                end
                #print("nbclasses: {classes.length} leaves: {smallest_classes.length} crown: {crown_classes.length} core: {core_classes.length}")

                # Colorize core color for typechecks
                colorize(ctab, crown_classes, 0)

                # Compute tables for typechecks
                var maxcolor = 0
                for c in classes do
                        var cc = compiled_classes[c.global]
                        if core_classes.has(c) then
                                # For core classes, just build the table
                                build_tables_in(cc.class_table, c, ctab)
                                if maxcolor < cc.class_table.length then maxcolor = cc.class_table.length
                        else
                                # For other classes, it's easier: just append to the parent tables
                                var sc = c.cshe.direct_greaters.first
                                var scc = compiled_classes[sc.global]
                                assert cc.class_table.is_empty
                                cc.class_table.add_all(scc.class_table)
                                var bc = c.global.intro
                                assert bc isa MMConcreteClass
                                var colpos = bc.class_color_pos
                                var colposcolor = cc.class_table.length
                                table_information.color(colpos) = colposcolor
                                cc.class_table.add(colpos)
                                if maxcolor < colposcolor then maxcolor = colposcolor
                        end
                end
                table_information.max_class_table_length = maxcolor + 1

                # Fill class table and instance tables pools
                for c in classes do
                        var cc = compiled_classes[c.global]
                        var cte = cc.class_layout
                        var ite = cc.instance_layout
                        for sc in c.crhe.greaters_and_self do
                                if sc isa MMConcreteClass then
                                        cte.add(sc, sc.class_layout)
                                        ite.add(sc, sc.instance_layout)
                                end
                        end

                        if core_classes.has(c) then
                                if cte.length > 0 then
                                        ctab.add(cte)
                                end
                                if ite.length > 0 then
                                        itab.add(ite)
                                end
                        end
                end

                # Colorize all elements in pools tables
                colorize(ctab, crown_classes, maxcolor+1)
                colorize(itab, crown_classes, 0)

                # Build class and instance tables now things are colored
                table_information.max_class_table_length = 0
                for c in classes do
                        var cc = compiled_classes[c.global]
                        if core_classes.has(c) then
                                # For core classes, just build the table
                                build_tables_in(cc.class_table, c, ctab)
                                build_tables_in(cc.instance_table, c, itab)
                        else
                                # For other classes, it's easier: just append to the parent tables
                                var sc = c.cshe.direct_greaters.first
                                var scc = compiled_classes[sc.global]
                                cc.class_table.clear
                                cc.class_table.add_all(scc.class_table)
                                var bc = c.global.intro
                                assert bc isa MMConcreteClass
                                var colpos = bc.class_color_pos
                                cc.class_table[table_information.color(colpos)] = colpos
                                while cc.class_table.length <= maxcolor do
                                        cc.class_table.add(null)
                                end
                                append_to_table(cc.class_table, cc.class_layout)
                                assert cc.instance_table.is_empty
                                cc.instance_table.add_all(scc.instance_table)
                                append_to_table(cc.instance_table, cc.instance_layout)
                        end
                end
        end

        # Perform coloring
        fun colorize(elts: Array[TableElt], classes: Collection[MMLocalClass], startcolor: Int)
        do
                var colors = new HashMap[Int, Array[TableElt]]
                var rel_classes = new Array[MMLocalClass]
                for e in elts do
                        var color = -1
                        var len = e.length
                        if table_information.has_color(e) then
                                color = table_information.color(e)
                        else
                                rel_classes.clear
                                for c in classes do
                                        if e.is_related_to(c) then
                                                rel_classes.add(c)
                                        end
                                end
                                var trycolor = startcolor
                                while trycolor != color do
                                        color = trycolor
                                        for c in rel_classes do
                                                var idx = 0
                                                while idx < len do
                                                        if colors.has_key(trycolor + idx) and not free_color(colors[trycolor + idx], c) then
                                                                trycolor = trycolor + idx + 1
                                                                idx = 0
                                                        else
                                                                idx = idx + 1
                                                        end
                                                end
                                        end
                                end
                                table_information.color(e) = color
                        end
                        for idx in [0..len[ do
                                if colors.has_key(color + idx) then
                                        colors[color + idx].add(e)
                                else
                                        colors[color + idx] = [e]
                                end
                        end
                end
        end

        private fun free_color(es: Array[TableElt], c: MMLocalClass): Bool
        do
                for e2 in es do
                        if e2.is_related_to(c) then
                                return false
                        end
                end
                return true
        end

        private fun append_to_table(table: Array[nullable TableElt], cmp: TableEltComposite)
        do
                for j in [0..cmp.length[ do
                        var e = cmp.item(j)
                        table_information.color(e) = table.length
                        table.add(e)
                end
        end

        private fun build_tables_in(table: Array[nullable TableElt], c: MMLocalClass, elts: Array[TableElt])
        do
                var tab = new HashMap[Int, TableElt]
                var len = 0
                for e in elts do
                        if e.is_related_to(c) then
                                var col = table_information.color(e)
                                var l = col + e.length
                                tab[col] = e
                                if len < l then
                                        len = l
                                end
                        end
                end
                var i = 0
                while i < len do
                        if tab.has_key(i) then
                                var e = tab[i]
                                for j in [0..e.length[ do
                                        table[i] = e.item(j)
                                        i = i + 1
                                end
                        else
                                table[i] = null
                                i = i + 1
                        end
                end
        end
end

redef class MMModule
        # The local table of the module (refers things introduced in the module)
        readable var _local_table: Array[ModuleTableElt] = new Array[ModuleTableElt]

        # Builds the local tables and local classes layouts
        private fun local_analysis
        do
                for c in local_classes do
                        if c isa MMConcreteClass then
                                c.build_layout_in(_local_table)
                        end
                end
        end
end

###############################################################################

# An element of a class, an instance or a module table
abstract class AbsTableElt
end

# An element of a class or an instance table
# Such an elements represent method function pointers, attribute values, etc.
abstract class TableElt
        super AbsTableElt
        # Is the element conflict to class `c' (used for coloring)
        fun is_related_to(c: MMLocalClass): Bool is abstract

        # Number of sub-elements. 1 if none
        fun length: Int do return 1

        # Access the ith subelement.
        fun item(i: Int): TableElt do return self
end

# An element of a module table
# Such an elements represent colors or identifiers
abstract class ModuleTableElt
        super AbsTableElt
end

# An element of a module table that represents a group of TableElt defined in the same local class
class ModuleTableEltGroup
        super ModuleTableElt
        readable var _elements: Array[TableElt] = new Array[TableElt]
end

# An element that represents a class property
abstract class TableEltProp
        super TableElt
        readable var _property: MMLocalProperty

        init(p: MMLocalProperty)
        do
                _property = p
        end
end

# An element that represents a function pointer to a global method
class TableEltMeth
        super TableEltProp
end

# An element that represents a class color value for a virtual type
class TableEltVTClassColor
        super TableEltProp
end

# An element that represents a class id value for a virtual type
class TableEltVTClassId
        super TableEltProp
end

# An element that represents a function pointer to the super method of a local method
class TableEltSuper
        super TableEltProp
end

# An element that represents the value stored for a global attribute
class TableEltAttr
        super TableEltProp
end

# An element representing a class information
class AbsTableEltClass
        super AbsTableElt
        # The local class where the information comes from
        readable var _local_class: MMLocalClass

        init(c: MMLocalClass)
        do
                _local_class = c
        end
end

# An element of a class table representing a class information
class TableEltClass
        super TableElt
        super AbsTableEltClass
        redef fun is_related_to(c)
        do
                var bc = c.mmmodule[_local_class.global]
                return c.cshe <= bc
        end
end

# An element representing the id of a class in a module table
class TableEltClassId
        super ModuleTableElt
        super AbsTableEltClass
end

# An element representing the constructor marker position in a class table
class TableEltClassInitTable
        super TableEltClass
end

# An element used for a cast
# Note: this element is both a TableElt and a ModuleTableElt.
# At the TableElt offset, there is the id of the super-class
# At the ModuleTableElt offset, there is the TableElt offset (ie. the color of the super-class).
class TableEltClassColor
        super TableEltClass
        super ModuleTableElt
end

# A Group of elements introduced in the same global-class that are colored together
class TableEltComposite
        super TableElt
        var _table: Array[TableElt]
        var _cc: CompiledClass
        var _offsets: HashMap[MMLocalClass, Int]
        redef fun length do return _table.length
        redef fun is_related_to(c) do return c.cshe <= _cc.local_class

        fun add(c: MMLocalClass, tab: Array[TableElt])
        do
                _offsets[c] = _table.length
                _table.append(tab)
        end

        redef fun item(i) do return _table[i]

        init(cc: CompiledClass)
        do
                _cc = cc
                _table = new Array[TableElt]
                _offsets = new HashMap[MMLocalClass, Int]
        end
end

# The element that represent the class id
class TableEltClassSelfId
        super TableElt
        redef fun is_related_to(c) do return true
end

# The element that represent the Object Size
class TableEltClassObjectSize
        super TableElt
        redef fun is_related_to(c) do return true
end

# The element that represent the object id
class TableEltObjectId
        super TableElt
        redef fun is_related_to(c) do return true
end

# The element that
class TableEltVftPointer
        super TableElt
        redef fun is_related_to(c) do return true
end