Revert "eliminate Undef and Top types. fixes #8631"

This reverts commit 84e80f4.

Major performance regressions. This commit will be back shortly when
fixed.

base/base.jl

@@ -271,7 +271,7 @@ call{T}(::Type{Array{T}}, m::Integer, n::Integer, o::Integer) =
 
 # TODO: possibly turn these into deprecations
 Array{T,N}(::Type{T}, d::NTuple{N,Int}) = Array{T}(d)
-Array{T}(::Type{T}, d::Integer...)      = Array{T}(convert((Int...), d))
+Array(T::Type, d::Integer...)           = Array{T}(convert((Int...), d))
 Array{T}(::Type{T}, m::Integer)                       = Array{T}(m)
 Array{T}(::Type{T}, m::Integer,n::Integer)            = Array{T}(m,n)
 Array{T}(::Type{T}, m::Integer,n::Integer,o::Integer) = Array{T}(m,n,o)

base/boot.jl

@@ -117,7 +117,7 @@ import Core.Intrinsics.ccall
 
 export
     # key types
-    Any, DataType, Vararg, ANY, NTuple,
+    Any, DataType, Vararg, ANY, NTuple, Top,
     Tuple, Type, TypeConstructor, TypeName, TypeVar, Union, UnionType, Void,
     AbstractArray, DenseArray,
     # special objects

base/inference.jl

@@ -15,7 +15,6 @@ type StaticVarInfo
     vars::Array{Any,1}   # names of args and locals
     gensym_types::Array{Any,1} # types of the GenSym's in this function
     label_counter::Int   # index of the current highest label for this function
-    fedbackvars::ObjectIdDict
 end
 
 type EmptyCallStack
@@ -343,7 +342,7 @@ const getfield_tfunc = function (A, s0, name)
             return abstract_eval_constant(eval(A1,fld))
         end
         if s === Module
-            return Any
+            return Top
         end
         if isType(s0)
             sp = s0.parameters[1]
@@ -940,6 +939,9 @@ end
 
 function abstract_eval_arg(a::ANY, vtypes::ANY, sv::StaticVarInfo)
     t = abstract_eval(a, vtypes, sv)
+    if isa(a,Symbol) || isa(a,SymbolNode) || isa(a,GenSym)
+        t = typeintersect(t,Any)  # remove Undef
+    end
     if isa(t,TypeVar) && t.lb == Bottom && isleaftype(t.ub)
         t = t.ub
     end
@@ -1016,18 +1018,19 @@ function abstract_eval(e::ANY, vtypes, sv::StaticVarInfo)
         abstract_eval(e.args[1], vtypes, sv)
         t = Any
     elseif is(e.head,:static_typeof)
-        var = e.args[1]
-        t = t0 = abstract_eval(var, vtypes, sv)
+        t0 = abstract_eval(e.args[1], vtypes, sv)
+        # intersect with Any to remove Undef
+        t = typeintersect(t0, Any)
         if isa(t,DataType) && typeseq(t,t.name.primary)
             # remove unnecessary typevars
             t = t.name.primary
         end
-        if is(t,Bottom)
-            # if we haven't gotten fed-back type info yet, return Bottom. otherwise
-            # Bottom is the actual type of the variable, so return Type{Bottom}.
-            if haskey(sv.fedbackvars, var)
-                t = Type{Bottom}
-            end
+        if is(t,Bottom) && Undef<:t0
+            # the first time we see this statement the variable will probably
+            # be Undef; return Bottom so this doesn't contribute to the type
+            # we eventually pick.
+        elseif is(t,Bottom)
+            t = Type{Bottom}
         elseif isleaftype(t)
             t = Type{t}
         elseif isleaftype(inference_stack.types)
@@ -1056,7 +1059,7 @@ function abstract_eval(e::ANY, vtypes, sv::StaticVarInfo)
     else
         t = Any
     end
-    if isa(t,TypeVar)
+    if isa(t,TypeVar) && t.lb === Bottom
         # no need to use a typevar as the type of an expression
         t = t.ub
     end
@@ -1079,20 +1082,30 @@ function abstract_eval_constant(x::ANY)
     return typeof(x)
 end
 
+# Undef is the static type of a value location (e.g. variable) that is
+# undefined. The corresponding run-time type is Bottom, since accessing an
+# undefined location is an error. A non-lvalue expression cannot have
+# type Undef, only Bottom.
+# typealias Top Union(Any,Undef)
+
 abstract_eval_global(s::Symbol) =
     abstract_eval_global((inference_stack::CallStack).mod, s)
 
 function abstract_eval_global(M, s::Symbol)
     if isconst(M,s)
         return abstract_eval_constant(eval(M,s))
     end
+    if !isdefined(M,s)
+        return Top
+    end
+    # TODO: change to Undef if there's a way to clear variables
     return Any
 end
 
 function abstract_eval_gensym(s::GenSym, sv::StaticVarInfo)
     typ = sv.gensym_types[s.id+1]
     if typ === NF
-        return Bottom
+        return Undef
     end
     return typ
 end
@@ -1124,7 +1137,7 @@ function abstract_eval_symbol(s::Symbol, vtypes::ObjectIdDict, sv::StaticVarInfo
         end
         if s in sv.vars
             # local variable use not reached
-            return Bottom
+            return Top
         end
         # global
         return abstract_eval_global(s)
@@ -1195,10 +1208,18 @@ function type_too_complex(t::ANY, d)
 end
 
 function tmerge(typea::ANY, typeb::ANY)
-    is(typea, NF ) && return typeb
-    is(typeb, NF)  && return typea
-    typea <: typeb && return typeb
-    typeb <: typea && return typea
+    if is(typea,NF)
+        return typeb
+    end
+    if is(typeb,NF)
+        return typea
+    end
+    if typea <: typeb
+        return typeb
+    end
+    if typeb <: typea
+        return typea
+    end
     if isa(typea, Tuple) && isa(typeb, Tuple)
         if length(typea) == length(typeb) && !isvatuple(typea) && !isvatuple(typeb)
             return typejoin(typea, typeb)
@@ -1209,7 +1230,7 @@ function tmerge(typea::ANY, typeb::ANY)
     if length(u.types) > MAX_TYPEUNION_LEN || type_too_complex(u, 0)
         # don't let type unions get too big
         # TODO: something smarter, like a common supertype
-        return Any
+        return Undef<:u ? Top : Any
     end
     return u
 end
@@ -1231,19 +1252,13 @@ function stupdate(state::ObjectIdDict, changes::Union(StateUpdate,VarTable), var
     state
 end
 
-function stchanged(new::Union(StateUpdate,VarTable), old, vinflist)
+function stchanged(new::Union(StateUpdate,VarTable), old, vars)
     if is(old,())
         return true
     end
-    for vi in vinflist
-        v = vi[1]
-        newtype = new[v]
-        oldtype = get(old,v,NF)
-        if (newtype === Bottom && oldtype !== NF && oldtype !== Bottom) ||
-            (oldtype === Bottom && newtype !== NF && newtype !== Bottom)
-            vi[3] |= 32
-        end
-        if tchanged(newtype, oldtype)
+    for i = 1:length(vars)
+        v = vars[i]
+        if tchanged(new[v], get(old,v,NF))
             return true
         end
     end
@@ -1442,7 +1457,7 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
     # initial types
     s[1] = ObjectIdDict()
     for v in vars
-        s[1][v] = Bottom
+        s[1][v] = Undef
     end
     if la > 0
         lastarg = ast.args[1][la]
@@ -1492,8 +1507,7 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
         cenv[vname] = vtype
         s[1][vname] = vtype
     end
-    vinflist = ast.args[2][2]::Array{Any,1}
-    for vi in vinflist
+    for vi = ((ast.args[2][2])::Array{Any,1})
         vi::Array{Any,1}
         if (vi[3]&4)!=0
             # variables assigned by inner functions are treated like
@@ -1509,7 +1523,7 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
     gensym_init = Any[ NF for i = 1:length(gensym_uses) ]
     gensym_types = copy(gensym_init)
 
-    sv = StaticVarInfo(sparams, cenv, vars, gensym_types, length(labels), ObjectIdDict())
+    sv = StaticVarInfo(sparams, cenv, vars, gensym_types, length(labels))
     frame.sv = sv
 
     recpts = IntSet()  # statements that depend recursively on our value
@@ -1551,7 +1565,7 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
             if !is(cur_hand,())
                 # propagate type info to exception handler
                 l = cur_hand[1]::Int
-                if stchanged(changes, s[l], vinflist)
+                if stchanged(changes, s[l], vars)
                     push!(W, l)
                     s[l] = stupdate(s[l], changes, vars)
                 end
@@ -1584,7 +1598,7 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
                     else
                         # general case
                         handler_at[l] = cur_hand
-                        if stchanged(changes, s[l], vinflist)
+                        if stchanged(changes, s[l], vars)
                             push!(W, l)
                             s[l] = stupdate(s[l], changes, vars)
                         end
@@ -1605,7 +1619,6 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
                             gensym_init[id] = vt
                             typegotoredo = true
                         end
-                        sv.fedbackvars[var] = true
                     end
                 elseif is(hd,:return)
                     pc´ = n+1
@@ -1650,7 +1663,7 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
                 end
             end
             if pc´<=n && (handler_at[pc´] = cur_hand; true) &&
-               stchanged(changes, s[pc´], vinflist)
+               stchanged(changes, s[pc´], vars)
                 s[pc´] = stupdate(s[pc´], changes, vars)
                 pc = pc´
             elseif pc´ in W
@@ -1739,7 +1752,7 @@ function record_var_type(e::Symbol, t::ANY, decls)
     end
 end
 
-function eval_annotate(e::ANY, vtypes::ANY, sv::StaticVarInfo, decls, clo, undefs)
+function eval_annotate(e::ANY, vtypes::ANY, sv::StaticVarInfo, decls, clo)
     if isa(e, Symbol)
         e = e::Symbol
 
@@ -1748,19 +1761,13 @@ function eval_annotate(e::ANY, vtypes::ANY, sv::StaticVarInfo, decls, clo, undef
             return e
         end
         t = abstract_eval(e, vtypes, sv)
-        if t === Bottom
-            undefs[e] = true
-        end
         record_var_type(e, t, decls)
         return (is(t,Any) || is(t,IntrinsicFunction)) ? e : SymbolNode(e, t)
     end
 
     if isa(e, SymbolNode)
         e = e::SymbolNode
         curtype = e.typ
-        if curtype === Bottom
-            undefs[e.name] = true
-        end
         t = abstract_eval(e.name, vtypes, sv)
         if !(curtype <: t) || typeseq(curtype, t)
             record_var_type(e.name, t, decls)
@@ -1793,7 +1800,7 @@ function eval_annotate(e::ANY, vtypes::ANY, sv::StaticVarInfo, decls, clo, undef
             # we don't use types on assignment LHS
             s = s.name
         end
-        e.args[2] = eval_annotate(e.args[2], vtypes, sv, decls, clo, undefs)
+        e.args[2] = eval_annotate(e.args[2], vtypes, sv, decls, clo)
         if isa(s,Symbol)
             # TODO: if this def does not reach any uses, maybe don't do this
             rhstype = exprtype(e.args[2], sv)
@@ -1807,7 +1814,7 @@ function eval_annotate(e::ANY, vtypes::ANY, sv::StaticVarInfo, decls, clo, undef
     for i=i0:length(e.args)
         subex = e.args[i]
         if !(isa(subex,Number) || isa(subex,AbstractString))
-            e.args[i] = eval_annotate(subex, vtypes, sv, decls, clo, undefs)
+            e.args[i] = eval_annotate(subex, vtypes, sv, decls, clo)
         end
     end
     if (head === :call || head === :call1) && isa(e.args[1],LambdaStaticData)
@@ -1825,7 +1832,6 @@ end
 function type_annotate(ast::Expr, states::Array{Any,1}, sv::ANY, rettype::ANY,
                        args)
     decls = ObjectIdDict()
-    undefs = ObjectIdDict()
     # initialize decls with argument types
     for arg in args
         decls[arg] = states[1][arg]
@@ -1836,7 +1842,7 @@ function type_annotate(ast::Expr, states::Array{Any,1}, sv::ANY, rettype::ANY,
         st_i = states[i]
         if st_i !== ()
             # st_i === ()  =>  unreached statement  (see issue #7836)
-            body[i] = eval_annotate(body[i], st_i, sv, decls, closures, undefs)
+            body[i] = eval_annotate(body[i], st_i, sv, decls, closures)
         end
     end
     ast.args[3].typ = rettype
@@ -1846,17 +1852,11 @@ function type_annotate(ast::Expr, states::Array{Any,1}, sv::ANY, rettype::ANY,
         if (vi[3]&4)==0
             vi[2] = get(decls, vi[1], vi[2])
         end
-        if haskey(undefs, vi[1])
-            vi[3] |= 32
-        end
     end
     for vi in ast.args[2][3]::Array{Any,1}
         if (vi[3]&4)==0
             vi[2] = get(decls, vi[1], vi[2])
         end
-        if haskey(undefs, vi[1])
-            vi[3] |= 32
-        end
     end
     ast.args[2][4] = sv.gensym_types
 
@@ -2350,6 +2350,7 @@ function inlineable(f::ANY, e::Expr, atypes::Tuple, sv::StaticVarInfo, enclosing
             for i = 1:numarg
                 name = newnames[i]
                 argtype = exprtype(argexprs[i],sv)
+                argtype = typeintersect(argtype,Any)  # remove Undef
                 push!(locals, Any[name,argtype,0])
                 push!(newcall.args, argtype===Any ? name : SymbolNode(name, argtype))
             end
@@ -3043,7 +3044,7 @@ function remove_redundant_temp_vars(ast, sa)
             # this transformation is not valid for vars used before def.
             # we need to preserve the point of assignment to know where to
             # throw errors (issue #4645).
-            if !occurs_undef(v, ast.args[3], varinfo)
+            if !occurs_undef(v, ast.args[3])
 
                 # the transformation is not ideal if the assignment
                 # is present for the auto-unbox functionality
@@ -3062,22 +3063,18 @@ end
 
 function local_typeof(v, varinfo)
     for (v2, typ, info) in varinfo
-        v === v2 && return typ
-    end
-    @assert false "v not in varinfo"
-end
-function var_infobits(v, varinfo)
-    for (v2, typ, info) in varinfo
-        v === v2 && return info
+        if v === v2
+            return typ
+        end
     end
     @assert false "v not in varinfo"
 end
 
-occurs_undef(var::GenSym, expr, varinfo) = false
+occurs_undef(var::GenSym, expr) = false
 
-occurs_undef(var, expr, varinfo) =
-    occurs_more(expr, e->(isa(e,SymbolNode) && symequal(var,e) &&
-                          ((var_infobits(e.name,varinfo)&32)!=0)), 0)>0
+occurs_undef(var, expr) =
+    occurs_more(expr,
+                e->(isa(e,SymbolNode) && symequal(var,e) && issubtype(Undef,e.typ)), 0)>0
 
 # compute set of vars assigned once
 function find_sa_vars(ast)

base/serialize.jl

@@ -22,7 +22,7 @@ let i = 2
              UTF16String, UTF32String, Float16,
              :reserved9, :reserved10, :reserved11, :reserved12,
 
-             (), Bool, Any, :Any, Bottom, :reserved21, :reserved22, Type,
+             (), Bool, Any, :Any, Bottom, Top, Undef, Type,
              :Array, :TypeVar, :Box,
              :lambda, :body, :return, :call, symbol("::"),
              :(=), :null, :gotoifnot, :A, :B, :C, :M, :N, :T, :S, :X, :Y,

base/show.jl

@@ -66,7 +66,13 @@ function show(io::IO, x::IntrinsicFunction)
     print(io, "(intrinsic function #", box(Int32,unbox(IntrinsicFunction,x)), ")")
 end
 
-show(io::IO, x::UnionType) = print(io, "Union", x.types)
+function show(io::IO, x::UnionType)
+    if is(x,Top)
+        print(io, "Top")
+    else
+        print(io, "Union", x.types)
+    end
+end
 
 show(io::IO, x::TypeConstructor) = show(io, x.body)