nit: Added link to `CONTRIBUTING.md` from the README

[nit.git] / src / rapid_type_analysis.nit

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


# Rapid type analysis on the AST
#
# Rapid type analysis is an analyse that aproximates the set of live classes
# and the set of live methods starting from the entry point of the program.
# These two sets are interdependant and computed together.
# It is quite efficient but the type set is global and pollutes each call site.
module rapid_type_analysis

import semantize

import csv # for live_types_to_csv
private import ordered_tree # for live_methods_to_tree

private import more_collections

redef class ModelBuilder
        # Performs a rapid-type-analysis on the program associated with `mainmodule`.
        fun do_rapid_type_analysis(mainmodule: MModule): RapidTypeAnalysis
        do
                var analysis = new RapidTypeAnalysis(self, mainmodule)
                analysis.run_analysis

                if toolcontext.opt_log.value then
                        var basename = toolcontext.log_directory / mainmodule.name
                        analysis.live_methods_to_tree.write_to_file(basename + ".rta_methods.txt")
                        analysis.live_types_to_csv.write_to_file(basename + ".rta_types.csv")
                end

                return analysis
        end
end

# RapidTypeAnalysis looks for alive rapid types in application.
# The entry point of the analysis is the mainmodule of the application.
class RapidTypeAnalysis
        # The modelbuilder used to get the AST.
        var modelbuilder: ModelBuilder

        # The main module of the analysis.
        # Used to perform types operations.
        var mainmodule: MModule

        # The pool to live types.
        # During the analysis, new types are added and combined with
        # live_methods to determine new methoddefs to visit
        var live_types = new HashSet[MClassType]

        # The pool of undesolved live types
        # They are globally resolved at the end of the analaysis
        var live_open_types = new HashSet[MClassType]

        # Live (instantiated) classes.
        var live_classes = new HashSet[MClass]

        # The pool of types used to perform type checks (isa and as).
        var live_cast_types = new HashSet[MType]

        # The pool of undesolved types used to perform type checks (isa and as).
        # They are globally resolved at the end of the analaysis
        var live_open_cast_types = new HashSet[MType]

        # Live method definitions.
        var live_methoddefs = new HashSet[MMethodDef]

        # Live methods.
        var live_methods = new HashSet[MMethod]

        # Live mmodules.
        # Those with a live method definitions (see `live_methoddefs`)
        var live_mmodules = new HashSet[MModule]

        # Live callsites.
        var live_callsites = new HashSet[CallSite]

        private var live_targets_cache = new HashMap2[MType, MProperty, Set[MMethodDef]]

        # The live targets of a specific callsite.
        fun live_targets(callsite: CallSite): Set[MMethodDef]
        do
                var mtype = callsite.recv
                var anchor = callsite.anchor
                if anchor != null then mtype = mtype.anchor_to(callsite.mmodule, anchor)
                mtype = mtype.undecorate
                if mtype isa MClassType then mtype = mtype.mclass.intro.bound_mtype
                var mproperty = callsite.mproperty
                var res = live_targets_cache[mtype, mproperty]
                if res != null then return res
                res = new ArraySet[MMethodDef]
                live_targets_cache[mtype, mproperty] = res

                for c in live_classes do
                        var tc = c.intro.bound_mtype
                        if not tc.is_subtype(mainmodule, null, mtype) then continue
                        var d = mproperty.lookup_first_definition(mainmodule, tc)
                        res.add d
                end

                return res
        end

        # Live call-to-super.
        var live_super_sends = new HashSet[MMethodDef]

        # Return a ready-to-save CSV document objet that agregates informations about live types.
        # Each discovered type is listed in a line, with its status: resolution, liveness, cast-liveness.
        # Note: types are listed in an alphanumeric order to improve human reading.
        fun live_types_to_csv: CsvDocument
        do
                # Gather all kind of type
                var typeset = new HashSet[MType]
                typeset.add_all(live_types)
                typeset.add_all(live_open_types)
                typeset.add_all(live_cast_types)
                typeset.add_all(live_open_cast_types)
                var types = typeset.to_a
                (new CachedAlphaComparator).sort(types)
                var res = new CsvDocument
                res.separator = ';'
                res.header = ["Type", "Resolution", "Liveness", "Cast-liveness"]
                for t in types do
                        var reso
                        if t.need_anchor then reso = "OPEN " else reso = "CLOSED"
                        var live
                        if t isa MClassType and (live_types.has(t) or live_open_types.has(t)) then live = "LIVE" else live = "DEAD"
                        var cast
                        if live_cast_types.has(t) or live_open_cast_types.has(t) then cast = "CAST LIVE" else cast = "CAST DEAD"
                        res.add_record(t, reso, live, cast)
                end
                return res
        end

        # Return a ready-to-save OrderedTree object that agregates infomration about live methods.
        # Note: methods are listed in an alphanumeric order to improve human reading.
        fun live_methods_to_tree: OrderedTree[Object]
        do
                var tree = new OrderedTree[Object]
                for x in live_methods do
                        var xn = x.full_name
                        tree.add(null, xn)
                        for z in x.mpropdefs do
                                var zn = z.to_s
                                if live_methoddefs.has(z) then
                                        tree.add(xn, zn)
                                        if live_super_sends.has(z) then
                                                tree.add(zn, zn + "(super)")
                                        end
                                else if live_super_sends.has(z) then
                                        tree.add(xn, zn + "(super)")
                                end
                        end
                end
                tree.sort_with(alpha_comparator)
                return tree
        end

        # Methods that are still candidate to the try_send
        private var totry_methods = new HashSet[MMethod]

        # Methods that are are no more candidate to the try_send
        private var totry_methods_to_remove = new Array[MMethod]

        # Methods that are or were candidate to the try_send
        # Used to ensure that try_send is only used once
        private var try_methods = new HashSet[MMethod]

        # The method definitions that remain to visit
        private var todo = new List[MMethodDef]

        private fun force_alive(classname: String)
        do
                var classes = self.modelbuilder.model.get_mclasses_by_name(classname)
                if classes != null then for c in classes do self.add_new(c.mclass_type, c.mclass_type)
        end

        # Run the analysis until all visitable method definitions are visited.
        fun run_analysis
        do
                var maintype = mainmodule.sys_type
                if maintype == null then return # No entry point
                add_new(maintype, maintype)
                var initprop = mainmodule.try_get_primitive_method("init", maintype.mclass)
                if initprop != null then
                        add_send(maintype, initprop)
                end
                var mainprop = mainmodule.try_get_primitive_method("run", maintype.mclass) or else
                        mainmodule.try_get_primitive_method("main", maintype.mclass)
                if mainprop != null then
                        add_send(maintype, mainprop)
                end

                var finalizable_type = mainmodule.finalizable_type
                if finalizable_type != null then
                        var finalize_meth = mainmodule.try_get_primitive_method("finalize", finalizable_type.mclass)
                        if finalize_meth != null then add_send(finalizable_type, finalize_meth)
                end

                # Force primitive types
                force_alive("Bool")
                force_alive("Float")
                force_alive("Char")
                force_alive("Pointer")
                force_alive("Byte")
                force_alive("Int")
                force_alive("Int8")
                force_alive("Int16")
                force_alive("UInt16")
                force_alive("Int32")
                force_alive("UInt32")

                while not todo.is_empty do
                        var mmethoddef = todo.shift
                        var mmeth = mmethoddef.mproperty
                        var msignature = mmethoddef.msignature
                        if msignature == null then continue # Skip broken method

                        #print "# visit {mmethoddef}"
                        var v = new RapidTypeVisitor(self, mmethoddef.mclassdef.bound_mtype, mmethoddef)

                        var vararg_rank = msignature.vararg_rank
                        if vararg_rank > -1 then
                                var node = self.modelbuilder.mpropdef2node(mmethoddef)
                                var elttype = msignature.mparameters[vararg_rank].mtype
                                #elttype = elttype.anchor_to(self.mainmodule, v.receiver)
                                var vararg = self.mainmodule.array_type(elttype)
                                v.add_type(vararg)
                                var native = self.mainmodule.native_array_type(elttype)
                                v.add_type(native)
                                v.add_monomorphic_send(vararg, self.modelbuilder.force_get_primitive_method(node, "with_native", vararg.mclass, self.mainmodule))
                        end

                        # TODO? new_msignature
                        var sig = msignature
                        var osig = mmeth.intro.msignature.as(not null)
                        for i in [0..sig.arity[ do
                                var origtype = osig.mparameters[i].mtype
                                if not origtype.need_anchor then continue # skip non covariant stuff
                                var paramtype = sig.mparameters[i].mtype
                                add_cast(paramtype)
                        end

                        var npropdef = modelbuilder.mpropdef2node(mmethoddef)

                        if npropdef isa AClassdef then
                                if mmethoddef.mproperty.is_root_init then
                                        if not mmethoddef.is_intro then
                                                self.add_super_send(v.receiver, mmethoddef)
                                        end
                                else
                                        npropdef.debug "cannot RTA {mmethoddef}"
                                        abort
                                end
                                continue
                        else if mmethoddef.constant_value != null then
                                # Make the return type live
                                v.add_type(msignature.return_mtype.as(MClassType))
                                continue
                        else if npropdef == null then
                                abort
                        end

                        if npropdef isa AMethPropdef then
                                var auto_super_inits = npropdef.auto_super_inits
                                if auto_super_inits != null then
                                        for auto_super_init in auto_super_inits do
                                                v.add_callsite(auto_super_init)
                                        end
                                end
                                if npropdef.auto_super_call then
                                        self.add_super_send(v.receiver, mmethoddef)
                                end
                        end

                        if mmethoddef.is_intern or mmethoddef.is_extern then
                                # UGLY: We force the "instantation" of the concrete return type if any
                                var ret = msignature.return_mtype
                                if ret != null and ret isa MClassType and ret.mclass.kind != abstract_kind and ret.mclass.kind != interface_kind then
                                        v.add_type(ret)
                                end
                        end

                        v.enter_visit(npropdef)
                end

                #print "MMethod {live_methods.length}: {live_methods.join(", ")}"
                #print "MMethodDef {live_methoddefs.length}: {live_methoddefs.join(", ")}"

                #print "open MType {live_open_types.length}: {live_open_types.join(", ")}"
                var todo_types = new List[MClassType]
                todo_types.add_all(live_types)
                while not todo_types.is_empty do
                        var t = todo_types.shift
                        for ot in live_open_types do
                                #print "{ot}/{t} ?"
                                if not ot.can_resolve_for(t, t, mainmodule) then continue
                                var rt = ot.anchor_to(mainmodule, t)
                                if live_types.has(rt) then continue
                                if not check_depth(rt) then continue
                                #print "{ot}/{t} -> {rt}"
                                live_types.add(rt)
                                todo_types.add(rt)
                        end
                end
                #print "MType {live_types.length}: {live_types.join(", ")}"

                #print "open cast MType {live_open_cast_types.length}: {live_open_cast_types.join(", ")}"
                for ot in live_open_cast_types do
                        #print "live_open_cast_type: {ot}"
                        for t in live_types do
                                if not ot.can_resolve_for(t, t, mainmodule) then continue
                                var rt = ot.anchor_to(mainmodule, t)
                                live_cast_types.add(rt)
                                #print "  {ot}/{t} -> {rt}"
                        end
                end
                #print "cast MType {live_cast_types.length}: {live_cast_types.join(", ")}"
        end

        private fun check_depth(mtype: MClassType): Bool
        do
                var d = mtype.length
                if d > 255 then
                        self.modelbuilder.toolcontext.fatal_error(null, "Fatal Error: limitation in the rapidtype analysis engine: a type depth of {d} is too important, the problematic type is `{mtype}`.")
                        return false
                end
                return true
        end

        fun add_new(recv: MClassType, mtype: MClassType)
        do
                assert not recv.need_anchor
                if mtype.need_anchor then
                        if live_open_types.has(mtype) then return
                        live_open_types.add(mtype)
                else
                        if live_types.has(mtype) then return
                        live_types.add(mtype)
                end

                var mclass = mtype.mclass
                if live_classes.has(mclass) then return
                live_classes.add(mclass)

                for p in totry_methods do try_send(mtype, p)
                for p in live_super_sends do try_super_send(mtype, p)

                # Remove cleared ones
                for p in totry_methods_to_remove do totry_methods.remove(p)
                totry_methods_to_remove.clear

                var bound_mtype = mtype.anchor_to(mainmodule, recv)
                for cd in bound_mtype.collect_mclassdefs(mainmodule)
                do
                        for npropdef in modelbuilder.collect_attr_propdef(cd) do
                                if not npropdef.has_value then continue

                                var mpropdef = npropdef.mreadpropdef.as(not null)
                                var v = new RapidTypeVisitor(self, bound_mtype, mpropdef)
                                v.enter_visit(npropdef.n_expr)
                                v.enter_visit(npropdef.n_block)
                        end
                end

        end

        fun add_cast(mtype: MType)
        do
                if mtype.need_anchor then
                        live_open_cast_types.add(mtype)
                else
                        live_cast_types.add(mtype)
                end
        end

        fun try_send(recv: MClassType, mproperty: MMethod)
        do
                recv = recv.mclass.intro.bound_mtype
                if not recv.has_mproperty(mainmodule, mproperty) then return
                var d = mproperty.lookup_first_definition(mainmodule, recv)
                add_call(d)
        end

        fun add_call(mpropdef: MMethodDef)
        do
                if live_methoddefs.has(mpropdef) then return
                live_methoddefs.add(mpropdef)
                live_mmodules.add(mpropdef.mclassdef.mmodule)
                todo.add(mpropdef)

                var mproperty = mpropdef.mproperty
                if mproperty.mpropdefs.length <= 1 then return
                # If all definitions of a method are live, we can remove the definition of the totry set
                for d in mproperty.mpropdefs do
                        if not live_methoddefs.has(d) then return
                end
                #print "full property: {mpropdef.mproperty} for {mpropdef.mproperty.mpropdefs.length} definitions"
                totry_methods_to_remove.add(mpropdef.mproperty)
        end

        fun add_send(recv: MType, mproperty: MMethod)
        do
                if try_methods.has(mproperty) then return
                #print "new prop: {mproperty}"
                live_methods.add(mproperty)
                try_methods.add(mproperty)
                if mproperty.mpropdefs.length == 1 then
                        # If there is only one definition, just add the definition and do not try again the property
                        var d = mproperty.mpropdefs.first
                        add_call(d)
                        return
                end
                # Else, the property is potentially called with various reciever
                # So just try the methods with existing receiver and register it for future receiver
                totry_methods.add(mproperty)
                for c in live_classes do
                        try_send(c.intro.bound_mtype, mproperty)
                end
        end

        fun try_super_send(recv: MClassType, mpropdef: MMethodDef)
        do
                recv = recv.mclass.intro.bound_mtype
                if not recv.collect_mclassdefs(mainmodule).has(mpropdef.mclassdef) then return
                var d = mpropdef.lookup_next_definition(mainmodule, recv)
                add_call(d)
        end

        fun add_super_send(recv: MType, mpropdef: MMethodDef)
        do
                assert mpropdef.has_supercall
                if live_super_sends.has(mpropdef) then return
                #print "new super prop: {mpropdef}"
                live_super_sends.add(mpropdef)
                for c in live_classes do
                        try_super_send(c.intro.bound_mtype, mpropdef)
                end
        end
end

class RapidTypeVisitor
        super Visitor

        var analysis: RapidTypeAnalysis
        var receiver: MClassType
        var mpropdef: MPropDef

        init
        do
                assert not receiver.need_anchor
        end

        redef fun visit(n)
        do
                if n isa AExpr then
                        if n.mtype != null or n.is_typed then
                                n.accept_rapid_type_visitor(self)
                                var implicit_cast_to = n.implicit_cast_to
                                if implicit_cast_to != null then self.add_cast_type(implicit_cast_to)
                        end
                else
                        n.accept_rapid_type_visitor(self)
                end

                # RTA does not enter in AAnnotations
                if not n isa AAnnotations then
                        n.visit_all(self)
                end
        end

        fun cleanup_type(mtype: MType): nullable MClassType
        do
                mtype = mtype.anchor_to(self.analysis.mainmodule, self.receiver)
                if mtype isa MNullType then return null
                mtype = mtype.undecorate
                assert mtype isa MClassType
                assert not mtype.need_anchor
                return mtype
        end

        fun get_method(recv: MType, name: String): MMethod
        do
                var mtype = cleanup_type(recv)
                assert mtype != null
                return self.analysis.modelbuilder.force_get_primitive_method(self.current_node.as(not null), name, mtype.mclass, self.analysis.mainmodule)
        end

        fun add_type(mtype: MClassType) do analysis.add_new(receiver, mtype)

        fun add_monomorphic_send(mtype: MType, mproperty: MMethod)
        do
                analysis.live_methods.add(mproperty)
                analysis.try_send(mtype.as(MClassType), mproperty)
        end

        fun add_send(mtype: MType, mproperty: MMethod) do analysis.add_send(mtype, mproperty)

        fun add_cast_type(mtype: MType) do analysis.add_cast(mtype)

        fun add_callsite(callsite: nullable CallSite) do if callsite != null then
                for m in callsite.mpropdef.initializers do
                        if m isa MMethod then
                                analysis.add_send(callsite.recv, m)
                        end
                end
                analysis.add_send(callsite.recv, callsite.mproperty)
                analysis.live_callsites.add(callsite)
        end
end

###

redef class ANode
        private fun accept_rapid_type_visitor(v: RapidTypeVisitor)
        do
        end
end

redef class AExpr
        # Make the `mtype` of the expression live
        # Used by literals and instantiations
        fun allocate_mtype(v: RapidTypeVisitor)
        do
                var mtype = self.mtype
                if not mtype isa MClassType then return
                v.add_type(self.mtype.as(MClassType))
        end
end

redef class AIntegerExpr
        redef fun accept_rapid_type_visitor(v)
        do
                allocate_mtype(v)
        end
end

redef class AFloatExpr
        redef fun accept_rapid_type_visitor(v)
        do
                allocate_mtype(v)
        end
end

redef class ACharExpr
        redef fun accept_rapid_type_visitor(v)
        do
                allocate_mtype(v)
        end
end

redef class AArrayExpr
        redef fun accept_rapid_type_visitor(v)
        do
                var mtype = self.mtype.as(MClassType)
                v.add_type(mtype)
                var native = v.analysis.mainmodule.native_array_type(mtype.arguments.first)
                v.add_type(native)
                mtype = v.cleanup_type(mtype).as(not null)
                var prop = v.get_method(mtype, "with_native")
                v.add_monomorphic_send(mtype, prop)
                v.add_callsite(with_capacity_callsite)
                v.add_callsite(push_callsite)
        end
end

redef class AStringFormExpr
        redef fun accept_rapid_type_visitor(v)
        do
                var native = v.analysis.mainmodule.native_string_type
                v.add_type(native)
                var prop = v.get_method(native, "to_s_full")
                v.add_monomorphic_send(native, prop)
                v.add_callsite(to_re)
                v.add_callsite(ignore_case)
                v.add_callsite(newline)
                v.add_callsite(extended)
                v.add_callsite(to_bytes_with_copy)
        end
end

redef class ASuperstringExpr
        redef fun accept_rapid_type_visitor(v)
        do
                var mmodule = v.analysis.mainmodule
                var object_type = mmodule.string_type
                var arraytype = mmodule.array_type(object_type)
                v.add_type(arraytype)
                var nattype = mmodule.native_array_type(object_type)
                v.add_type(nattype)
                var prop = v.get_method(arraytype, "join")
                v.add_monomorphic_send(arraytype, prop)
                var prop2 = v.get_method(arraytype, "with_native")
                v.add_monomorphic_send(arraytype, prop2)
                v.add_monomorphic_send(nattype, v.get_method(nattype, "native_to_s"))
        end
end

redef class ACrangeExpr
        redef fun accept_rapid_type_visitor(v)
        do
                var mtype = self.mtype
                if not mtype isa MClassType then return
                v.add_type(mtype)
                v.add_callsite(init_callsite)
        end
end

redef class AOrangeExpr
        redef fun accept_rapid_type_visitor(v)
        do
                var mtype = self.mtype
                if not mtype isa MClassType then return
                v.add_type(mtype)
                v.add_callsite(init_callsite)
        end
end

redef class ATrueExpr
        redef fun accept_rapid_type_visitor(v)
        do
                allocate_mtype(v)
        end
end

redef class AFalseExpr
        redef fun accept_rapid_type_visitor(v)
        do
                allocate_mtype(v)
        end
end

redef class AIsaExpr
        redef fun accept_rapid_type_visitor(v)
        do
                var cast_type = self.cast_type
                if cast_type == null then return
                v.add_cast_type(cast_type)
        end
end

redef class AAsCastExpr
        redef fun accept_rapid_type_visitor(v)
        do
                var mtype = self.mtype
                if mtype == null then return
                v.add_cast_type(mtype)
        end
end

redef class ASendExpr
        redef fun accept_rapid_type_visitor(v)
        do
                v.add_callsite(callsite)
        end
end


redef class ASendReassignFormExpr
        redef fun accept_rapid_type_visitor(v)
        do
                v.add_callsite(callsite)
                v.add_callsite(reassign_callsite)
                v.add_callsite(write_callsite)
        end
end

redef class AVarReassignExpr
        redef fun accept_rapid_type_visitor(v)
        do
                v.add_callsite(reassign_callsite)
        end
end

redef class AAttrReassignExpr
        redef fun accept_rapid_type_visitor(v)
        do
                v.add_callsite(reassign_callsite)
        end
end

redef class ASuperExpr
        redef fun accept_rapid_type_visitor(v)
        do
                var callsite = self.callsite
                if callsite != null then
                        v.add_callsite(callsite)
                        return
                end

                v.analysis.add_super_send(v.receiver, mpropdef.as(not null))
        end
end

redef class AForGroup
        redef fun accept_rapid_type_visitor(v)
        do
                v.add_callsite(self.method_iterator)
                v.add_callsite(self.method_is_ok)
                if self.variables.length == 1 then
                        v.add_callsite(self.method_item)
                else if self.variables.length == 2 then
                        v.add_callsite(self.method_key)
                        v.add_callsite(self.method_item)
                else
                        abort
                end
                v.add_callsite(self.method_next)
                var mf = self.method_finish
                if mf != null then v.add_callsite(mf)
        end
end

redef class ANewExpr
        redef fun accept_rapid_type_visitor(v)
        do
                var mtype = self.recvtype.as(not null)
                v.add_type(mtype)
                v.add_callsite(callsite)
        end
end