inference: fix stupdate for Conditional after slot re-assignment (Jul…

…iaLang#25602)

We were neglecting to clear Conditional objects upon assignment to their attached slot
(which invalidates their knowledge of the contents of that slot)

fixes JuliaLang#25579

base/compiler/typelattice.jl

@@ -28,11 +28,11 @@ end
 # end
 # ```
 mutable struct Conditional
- var::Union{Slot,SSAValue}
+ var::Slot
  vtype
  elsetype
  function Conditional(
- @nospecialize(var),
+ var,
  @nospecialize(vtype),
  @nospecialize(nottype))
  return new(var, vtype, nottype)
@@ -215,27 +215,55 @@ end
 @inline tchanged(@nospecialize(n), @nospecialize(o)) = o === NOT_FOUND || (n !== NOT_FOUND && !(n ⊑ o))
 @inline schanged(@nospecialize(n), @nospecialize(o)) = (n !== o) && (o === NOT_FOUND || (n !== NOT_FOUND && !issubstate(n, o)))
 
+function widenconditional(typ::Conditional)
+ if typ.vtype == Union{}
+ return Const(false)
+ elseif typ.elsetype == Union{}
+ return Const(true)
+ else
+ return Bool
+ end
+end
+
 function stupdate!(state::Tuple{}, changes::StateUpdate)
  newst = copy(changes.state)
  if isa(changes.var, Slot)
- newst[slot_id(changes.var::Slot)] = changes.vtype
+ changeid = slot_id(changes.var::Slot)
+ newst[changeid] = changes.vtype
+ # remove any Conditional for this Slot from the vtable
+ for i = 1:length(newst)
+ newtype = newst[i]
+ if isa(newtype, VarState)
+ newtypetyp = newtype.typ
+ if isa(newtypetyp, Conditional) && slot_id(newtypetyp.var) == changeid
+ newst[i] = VarState(widenconditional(newtypetyp), newtype.undef)
+ end
+ end
+ end
  end
  return newst
 end
 
-function stupdate!(state::VarTable, change::StateUpdate)
- if !isa(change.var, Slot)
- return stupdate!(state, change.state)
+function stupdate!(state::VarTable, changes::StateUpdate)
+ if !isa(changes.var, Slot)
+ return stupdate!(state, changes.state)
  end
  newstate = false
- changeid = slot_id(change.var::Slot)
+ changeid = slot_id(changes.var::Slot)
  for i = 1:length(state)
  if i == changeid
- newtype = change.vtype
+ newtype = changes.vtype
  else
- newtype = change.state[i]
+ newtype = changes.state[i]
  end
  oldtype = state[i]
+ # remove any Conditional for this Slot from the vtable
+ if isa(newtype, VarState)
+ newtypetyp = newtype.typ
+ if isa(newtypetyp, Conditional) && slot_id(newtypetyp.var) == changeid
+ newtype = VarState(widenconditional(newtypetyp), newtype.undef)
+ end
+ end
  if schanged(newtype, oldtype)
  newstate = state
  state[i] = smerge(oldtype, newtype)
@@ -265,11 +293,22 @@ function stupdate1!(state::VarTable, change::StateUpdate)
  if !isa(change.var, Slot)
  return false
  end
- i = slot_id(change.var::Slot)
+ changeid = slot_id(change.var::Slot)
+ # remove any Conditional for this Slot from the catch block vtable
+ for i = 1:length(state)
+ oldtype = state[i]
+ if isa(oldtype, VarState)
+ oldtypetyp = oldtype.typ
+ if isa(oldtypetyp, Conditional) && slot_id(oldtypetyp.var) == changeid
+ state[i] = VarState(widenconditional(oldtypetyp), oldtype.undef)
+ end
+ end
+ end
+ # and update the type of it
  newtype = change.vtype
- oldtype = state[i]
+ oldtype = state[changeid]
  if schanged(newtype, oldtype)
- state[i] = smerge(oldtype, newtype)
+ state[changeid] = smerge(oldtype, newtype)
  return true
  end
  return false

test/compiler/compiler.jl

@@ -1417,4 +1417,31 @@ for expr25261 in opt25261[i:end]
  @test expr25261.args[2].typ === Tuple{Int, Int}
  global foundslot = true
 end
-@test foundslot
+@test foundslot
+
+function f25579(g)
+ h = g[]
+ t = (h === nothing)
+ h = 3.0
+ return t ? typeof(h) : typeof(h)
+end
+@test @inferred f25579(Ref{Union{Nothing, Int}}(nothing)) == Float64
+@test @inferred f25579(Ref{Union{Nothing, Int}}(1)) == Float64
+function g25579(g)
+ h = g[]
+ h = (h === nothing)
+ return h ? typeof(h) : typeof(h)
+end
+@test @inferred g25579(Ref{Union{Nothing, Int}}(nothing)) == Bool
+@test @inferred g25579(Ref{Union{Nothing, Int}}(1)) == Bool
+function h25579(g)
+ h = g[]
+ t = (h === nothing)
+ try
+ h = -1.25
+ error("continue at catch block")
+ end
+ return t ? typeof(h) : typeof(h)
+end
+@test Base.return_types(h25579, (Base.RefValue{Union{Nothing, Int}},)) ==
+ Any[Union{Type{Float64}, Type{Int}, Type{Nothing}}]