diff --git a/base/compiler/abstractinterpretation.jl b/base/compiler/abstractinterpretation.jl
index 52a9eb1a02ccd..296a30cdb2e0f 100644
--- a/base/compiler/abstractinterpretation.jl
+++ b/base/compiler/abstractinterpretation.jl
@@ -85,9 +85,12 @@ function abstract_call_gf_by_type(interp::AbstractInterpreter, @nospecialize(f),
                     push!(edges, edge)
                 end
                 this_argtypes = isa(matches, MethodMatches) ? argtypes : matches.applicable_argtypes[i]
-                const_rt, const_result = abstract_call_method_with_const_args(interp, result, f, this_argtypes, match, sv, false)
-                if const_rt !== rt && const_rt ⊑ rt
-                    rt = const_rt
+                const_result = abstract_call_method_with_const_args(interp, result, f, this_argtypes, match, sv, false)
+                if const_result !== nothing
+                    const_rt, const_result = const_result
+                    if const_rt !== rt && const_rt ⊑ rt
+                        rt = const_rt
+                    end
                 end
                 push!(const_results, const_result)
                 if const_result !== nothing
@@ -107,9 +110,12 @@ function abstract_call_gf_by_type(interp::AbstractInterpreter, @nospecialize(f),
             # try constant propagation with argtypes for this match
             # this is in preparation for inlining, or improving the return result
             this_argtypes = isa(matches, MethodMatches) ? argtypes : matches.applicable_argtypes[i]
-            const_this_rt, const_result = abstract_call_method_with_const_args(interp, result, f, this_argtypes, match, sv, false)
-            if const_this_rt !== this_rt && const_this_rt ⊑ this_rt
-                this_rt = const_this_rt
+            const_result = abstract_call_method_with_const_args(interp, result, f, this_argtypes, match, sv, false)
+            if const_result !== nothing
+                const_this_rt, const_result = const_result
+                if const_this_rt !== this_rt && const_this_rt ⊑ this_rt
+                    this_rt = const_this_rt
+                end
             end
             push!(const_results, const_result)
             if const_result !== nothing
@@ -523,33 +529,35 @@ function abstract_call_method_with_const_args(interp::AbstractInterpreter, resul
                                               @nospecialize(f), argtypes::Vector{Any}, match::MethodMatch,
                                               sv::InferenceState, va_override::Bool)
     mi = maybe_get_const_prop_profitable(interp, result, f, argtypes, match, sv)
-    mi === nothing && return Any, nothing
+    mi === nothing && return nothing
     # try constant prop'
     inf_cache = get_inference_cache(interp)
     inf_result = cache_lookup(mi, argtypes, inf_cache)
     if inf_result === nothing
         # if there might be a cycle, check to make sure we don't end up
         # calling ourselves here.
-        if result.edgecycle && _any(InfStackUnwind(sv)) do infstate
-                # if the type complexity limiting didn't decide to limit the call signature (`result.edgelimited = false`)
-                # we can relax the cycle detection by comparing `MethodInstance`s and allow inference to
-                # propagate different constant elements if the recursion is finite over the lattice
-                return (result.edgelimited ? match.method === infstate.linfo.def : mi === infstate.linfo) &&
-                        any(infstate.result.overridden_by_const)
+        let result = result # prevent capturing
+            if result.edgecycle && _any(InfStackUnwind(sv)) do infstate
+                    # if the type complexity limiting didn't decide to limit the call signature (`result.edgelimited = false`)
+                    # we can relax the cycle detection by comparing `MethodInstance`s and allow inference to
+                    # propagate different constant elements if the recursion is finite over the lattice
+                    return (result.edgelimited ? match.method === infstate.linfo.def : mi === infstate.linfo) &&
+                            any(infstate.result.overridden_by_const)
+                end
+                add_remark!(interp, sv, "[constprop] Edge cycle encountered")
+                return nothing
             end
-            add_remark!(interp, sv, "[constprop] Edge cycle encountered")
-            return Any, nothing
         end
         inf_result = InferenceResult(mi, argtypes, va_override)
         frame = InferenceState(inf_result, #=cache=#false, interp)
-        frame === nothing && return Any, nothing # this is probably a bad generated function (unsound), but just ignore it
+        frame === nothing && return nothing # this is probably a bad generated function (unsound), but just ignore it
         frame.parent = sv
         push!(inf_cache, inf_result)
-        typeinf(interp, frame) || return Any, nothing
+        typeinf(interp, frame) || return nothing
     end
     result = inf_result.result
     # if constant inference hits a cycle, just bail out
-    isa(result, InferenceState) && return Any, nothing
+    isa(result, InferenceState) && return nothing
     add_backedge!(mi, sv)
     return result, inf_result
 end
@@ -1174,7 +1182,8 @@ function abstract_invoke(interp::AbstractInterpreter, argtypes::Vector{Any}, sv:
     nargtype === Bottom && return CallMeta(Bottom, false)
     nargtype isa DataType || return CallMeta(Any, false) # other cases are not implemented below
     isdispatchelem(ft) || return CallMeta(Any, false) # check that we might not have a subtype of `ft` at runtime, before doing supertype lookup below
-    types = rewrap_unionall(Tuple{ft, unwrap_unionall(types).parameters...}, types)
+    ft = ft::DataType
+    types = rewrap_unionall(Tuple{ft, unwrap_unionall(types).parameters...}, types)::Type
     nargtype = Tuple{ft, nargtype.parameters...}
     argtype = Tuple{ft, argtype.parameters...}
     result = findsup(types, method_table(interp))
@@ -1196,12 +1205,14 @@ function abstract_invoke(interp::AbstractInterpreter, argtypes::Vector{Any}, sv:
     #     t, a = ti.parameters[i], argtypes′[i]
     #     argtypes′[i] = t ⊑ a ? t : a
     # end
-    const_rt, const_result = abstract_call_method_with_const_args(interp, result, argtype_to_function(ft′), argtypes′, match, sv, false)
-    if const_rt !== rt && const_rt ⊑ rt
-        return CallMeta(const_rt, InvokeCallInfo(match, const_result))
-    else
-        return CallMeta(rt, InvokeCallInfo(match, nothing))
+    const_result = abstract_call_method_with_const_args(interp, result, argtype_to_function(ft′), argtypes′, match, sv, false)
+    if const_result !== nothing
+        const_rt, const_result = const_result
+        if const_rt !== rt && const_rt ⊑ rt
+            return CallMeta(const_rt, InvokeCallInfo(match, const_result))
+        end
     end
+    return CallMeta(rt, InvokeCallInfo(match, nothing))
 end
 
 # call where the function is known exactly
@@ -1301,19 +1312,20 @@ end
 function abstract_call_opaque_closure(interp::AbstractInterpreter, closure::PartialOpaque, argtypes::Vector{Any}, sv::InferenceState)
     pushfirst!(argtypes, closure.env)
     sig = argtypes_to_type(argtypes)
-    (; rt, edge) = result = abstract_call_method(interp, closure.source::Method, sig, Core.svec(), false, sv)
+    (; rt, edge) = result = abstract_call_method(interp, closure.source, sig, Core.svec(), false, sv)
     edge !== nothing && add_backedge!(edge, sv)
     tt = closure.typ
-    sigT = unwrap_unionall(tt).parameters[1]
-    match = MethodMatch(sig, Core.svec(), closure.source::Method, sig <: rewrap_unionall(sigT, tt))
+    sigT = (unwrap_unionall(tt)::DataType).parameters[1]
+    match = MethodMatch(sig, Core.svec(), closure.source, sig <: rewrap_unionall(sigT, tt))
     info = OpaqueClosureCallInfo(match)
     if !result.edgecycle
-        const_rettype, const_result = abstract_call_method_with_const_args(interp, result, closure, argtypes,
+        const_result = abstract_call_method_with_const_args(interp, result, closure, argtypes,
             match, sv, closure.isva)
-        if const_rettype ⊑ rt
-           rt = const_rettype
-        end
         if const_result !== nothing
+            const_rettype, const_result = const_result
+            if const_rettype ⊑ rt
+               rt = const_rettype
+            end
             info = ConstCallInfo(info, Union{Nothing,InferenceResult}[const_result])
         end
     end
@@ -1323,7 +1335,7 @@ end
 function most_general_argtypes(closure::PartialOpaque)
     ret = Any[]
     cc = widenconst(closure)
-    argt = unwrap_unionall(cc).parameters[1]
+    argt = (unwrap_unionall(cc)::DataType).parameters[1]
     if !isa(argt, DataType) || argt.name !== typename(Tuple)
         argt = Tuple
     end
@@ -1338,8 +1350,8 @@ function abstract_call(interp::AbstractInterpreter, fargs::Union{Nothing,Vector{
     f = argtype_to_function(ft)
     if isa(ft, PartialOpaque)
         return abstract_call_opaque_closure(interp, ft, argtypes[2:end], sv)
-    elseif isa(unwrap_unionall(ft), DataType) && unwrap_unionall(ft).name === typename(Core.OpaqueClosure)
-        return CallMeta(rewrap_unionall(unwrap_unionall(ft).parameters[2], ft), false)
+    elseif (uft = unwrap_unionall(ft); isa(uft, DataType) && uft.name === typename(Core.OpaqueClosure))
+        return CallMeta(rewrap_unionall((uft::DataType).parameters[2], ft), false)
     elseif f === nothing
         # non-constant function, but the number of arguments is known
         # and the ft is not a Builtin or IntrinsicFunction
@@ -1534,12 +1546,12 @@ function abstract_eval_statement(interp::AbstractInterpreter, @nospecialize(e),
         if length(e.args) == 2 && isconcretetype(t) && !ismutabletype(t)
             at = abstract_eval_value(interp, e.args[2], vtypes, sv)
             n = fieldcount(t)
-            if isa(at, Const) && isa(at.val, Tuple) && n == length(at.val) &&
-                let t = t; _all(i->getfield(at.val, i) isa fieldtype(t, i), 1:n); end
+            if isa(at, Const) && isa(at.val, Tuple) && n == length(at.val::Tuple) &&
+                let t = t; _all(i->getfield(at.val::Tuple, i) isa fieldtype(t, i), 1:n); end
                 t = Const(ccall(:jl_new_structt, Any, (Any, Any), t, at.val))
-            elseif isa(at, PartialStruct) && at ⊑ Tuple && n == length(at.fields) &&
-                let t = t, at = at; _all(i->at.fields[i] ⊑ fieldtype(t, i), 1:n); end
-                t = PartialStruct(t, at.fields)
+            elseif isa(at, PartialStruct) && at ⊑ Tuple && n == length(at.fields::Vector{Any}) &&
+                let t = t, at = at; _all(i->(at.fields::Vector{Any})[i] ⊑ fieldtype(t, i), 1:n); end
+                t = PartialStruct(t, at.fields::Vector{Any})
             end
         end
     elseif e.head === :new_opaque_closure
@@ -1587,7 +1599,7 @@ function abstract_eval_statement(interp::AbstractInterpreter, @nospecialize(e),
         sym = e.args[1]
         t = Bool
         if isa(sym, SlotNumber)
-            vtyp = vtypes[slot_id(sym)]
+            vtyp = vtypes[slot_id(sym)]::VarState
             if vtyp.typ === Bottom
                 t = Const(false) # never assigned previously
             elseif !vtyp.undef
@@ -1602,7 +1614,7 @@ function abstract_eval_statement(interp::AbstractInterpreter, @nospecialize(e),
                 t = Const(true)
             end
         elseif isa(sym, Expr) && sym.head === :static_parameter
-            n = sym.args[1]
+            n = sym.args[1]::Int
             if 1 <= n <= length(sv.sptypes)
                 spty = sv.sptypes[n]
                 if isa(spty, Const)
@@ -1637,7 +1649,7 @@ function abstract_eval_global(M::Module, s::Symbol)
 end
 
 function abstract_eval_ssavalue(s::SSAValue, src::CodeInfo)
-    typ = src.ssavaluetypes[s.id]
+    typ = (src.ssavaluetypes::Vector{Any})[s.id]
     if typ === NOT_FOUND
         return Bottom
     end
@@ -1725,6 +1737,7 @@ function typeinf_local(interp::AbstractInterpreter, frame::InferenceState)
     isva = isa(def, Method) && def.isva
     nslots = nargs - isva
     slottypes = frame.slottypes
+    ssavaluetypes = frame.src.ssavaluetypes::Vector{Any}
     while frame.pc´´ <= n
         # make progress on the active ip set
         local pc::Int = frame.pc´´ # current program-counter
@@ -1828,7 +1841,7 @@ function typeinf_local(interp::AbstractInterpreter, frame::InferenceState)
                     for (caller, caller_pc) in frame.cycle_backedges
                         # notify backedges of updated type information
                         typeassert(caller.stmt_types[caller_pc], VarTable) # we must have visited this statement before
-                        if !(caller.src.ssavaluetypes[caller_pc] === Any)
+                        if !((caller.src.ssavaluetypes::Vector{Any})[caller_pc] === Any)
                             # no reason to revisit if that call-site doesn't affect the final result
                             if caller_pc < caller.pc´´
                                 caller.pc´´ = caller_pc
@@ -1838,6 +1851,7 @@ function typeinf_local(interp::AbstractInterpreter, frame::InferenceState)
                     end
                 end
             elseif hd === :enter
+                stmt = stmt::Expr
                 l = stmt.args[1]::Int
                 frame.cur_hand = Pair{Any,Any}(l, frame.cur_hand)
                 # propagate type info to exception handler
@@ -1853,21 +1867,24 @@ function typeinf_local(interp::AbstractInterpreter, frame::InferenceState)
                 typeassert(states[l], VarTable)
                 frame.handler_at[l] = frame.cur_hand
             elseif hd === :leave
+                stmt = stmt::Expr
                 for i = 1:((stmt.args[1])::Int)
                     frame.cur_hand = (frame.cur_hand::Pair{Any,Any}).second
                 end
             else
                 if hd === :(=)
+                    stmt = stmt::Expr
                     t = abstract_eval_statement(interp, stmt.args[2], changes, frame)
                     if t === Bottom
                         break
                     end
-                    frame.src.ssavaluetypes[pc] = t
+                    ssavaluetypes[pc] = t
                     lhs = stmt.args[1]
                     if isa(lhs, SlotNumber)
                         changes = StateUpdate(lhs, VarState(t, false), changes, false)
                     end
                 elseif hd === :method
+                    stmt = stmt::Expr
                     fname = stmt.args[1]
                     if isa(fname, SlotNumber)
                         changes = StateUpdate(fname, VarState(Any, false), changes, false)
@@ -1882,7 +1899,7 @@ function typeinf_local(interp::AbstractInterpreter, frame::InferenceState)
                     if !isempty(frame.ssavalue_uses[pc])
                         record_ssa_assign(pc, t, frame)
                     else
-                        frame.src.ssavaluetypes[pc] = t
+                        ssavaluetypes[pc] = t
                     end
                 end
                 if frame.cur_hand !== nothing && isa(changes, StateUpdate)
@@ -1903,7 +1920,7 @@ function typeinf_local(interp::AbstractInterpreter, frame::InferenceState)
 
             if t === nothing
                 # mark other reached expressions as `Any` to indicate they don't throw
-                frame.src.ssavaluetypes[pc] = Any
+                ssavaluetypes[pc] = Any
             end
 
             pc´ > n && break # can't proceed with the fast-path fall-through
diff --git a/base/compiler/inferencestate.jl b/base/compiler/inferencestate.jl
index a3f2b1ea95d27..d76a4ebd18f6e 100644
--- a/base/compiler/inferencestate.jl
+++ b/base/compiler/inferencestate.jl
@@ -179,7 +179,7 @@ function sptypes_from_meth_instance(linfo::MethodInstance)
             while temp isa UnionAll
                 temp = temp.body
             end
-            sigtypes = temp.parameters
+            sigtypes = (temp::DataType).parameters
             for j = 1:length(sigtypes)
                 tj = sigtypes[j]
                 if isType(tj) && tj.parameters[1] === Pi
diff --git a/base/compiler/ssair/legacy.jl b/base/compiler/ssair/legacy.jl
index a921c2eac70c5..a832daa8ed418 100644
--- a/base/compiler/ssair/legacy.jl
+++ b/base/compiler/ssair/legacy.jl
@@ -47,7 +47,7 @@ function replace_code_newstyle!(ci::CodeInfo, ir::IRCode, nargs::Int)
     for metanode in ir.meta
         push!(ci.code, metanode)
         push!(ci.codelocs, 1)
-        push!(ci.ssavaluetypes, Any)
+        push!(ci.ssavaluetypes::Vector{Any}, Any)
         push!(ci.ssaflags, 0x00)
     end
     # Translate BB Edges to statement edges
diff --git a/base/compiler/ssair/passes.jl b/base/compiler/ssair/passes.jl
index 37f5d38940e05..838ab5bd21755 100644
--- a/base/compiler/ssair/passes.jl
+++ b/base/compiler/ssair/passes.jl
@@ -1066,7 +1066,7 @@ function type_lift_pass!(ir::IRCode)
                                         if haskey(processed, id)
                                             val = processed[id]
                                         else
-                                            push!(worklist, (id, up_id, new_phi, i))
+                                            push!(worklist, (id, up_id, new_phi::SSAValue, i))
                                             continue
                                         end
                                     else
diff --git a/base/compiler/ssair/slot2ssa.jl b/base/compiler/ssair/slot2ssa.jl
index 3c3e7fcfc48b3..6ca17be2f0a83 100644
--- a/base/compiler/ssair/slot2ssa.jl
+++ b/base/compiler/ssair/slot2ssa.jl
@@ -873,7 +873,7 @@ function construct_ssa!(ci::CodeInfo, ir::IRCode, domtree::DomTree, defuse,
         changed = false
         for new_idx in type_refine_phi
             node = new_nodes.stmts[new_idx]
-            new_typ = recompute_type(node[:inst], ci, ir, ir.sptypes, slottypes)
+            new_typ = recompute_type(node[:inst]::Union{PhiNode,PhiCNode}, ci, ir, ir.sptypes, slottypes)
             if !(node[:type] ⊑ new_typ) || !(new_typ ⊑ node[:type])
                 node[:type] = new_typ
                 changed = true
diff --git a/base/compiler/tfuncs.jl b/base/compiler/tfuncs.jl
index 09aa05f35b9f0..772db09417393 100644
--- a/base/compiler/tfuncs.jl
+++ b/base/compiler/tfuncs.jl
@@ -1564,7 +1564,7 @@ function builtin_tfunction(interp::AbstractInterpreter, @nospecialize(f), argtyp
         if length(argtypes) - 1 == tf[2]
             argtypes = argtypes[1:end-1]
         else
-            vatype = argtypes[end]
+            vatype = argtypes[end]::Core.TypeofVararg
             argtypes = argtypes[1:end-1]
             while length(argtypes) < tf[1]
                 push!(argtypes, unwrapva(vatype))
@@ -1670,7 +1670,7 @@ function return_type_tfunc(interp::AbstractInterpreter, argtypes::Vector{Any}, s
             aft = argtypes[2]
             if isa(aft, Const) || (isType(aft) && !has_free_typevars(aft)) ||
                    (isconcretetype(aft) && !(aft <: Builtin))
-                af_argtype = isa(tt, Const) ? tt.val : tt.parameters[1]
+                af_argtype = isa(tt, Const) ? tt.val : (tt::DataType).parameters[1]
                 if isa(af_argtype, DataType) && af_argtype <: Tuple
                     argtypes_vec = Any[aft, af_argtype.parameters...]
                     if contains_is(argtypes_vec, Union{})
diff --git a/base/compiler/typeinfer.jl b/base/compiler/typeinfer.jl
index 246f66fc64ed8..1d2559cf10c3a 100644
--- a/base/compiler/typeinfer.jl
+++ b/base/compiler/typeinfer.jl
@@ -243,7 +243,7 @@ function _typeinf(interp::AbstractInterpreter, frame::InferenceState)
     # collect results for the new expanded frame
     results = Tuple{InferenceResult, Vector{Any}, Bool}[
             ( frames[i].result,
-              frames[i].stmt_edges[1],
+              frames[i].stmt_edges[1]::Vector{Any},
               frames[i].cached )
         for i in 1:length(frames) ]
     empty!(frames)
@@ -341,7 +341,7 @@ function maybe_compress_codeinfo(interp::AbstractInterpreter, linfo::MethodInsta
     if cache_the_tree
         if may_compress(interp)
             nslots = length(ci.slotflags)
-            resize!(ci.slottypes, nslots)
+            resize!(ci.slottypes::Vector{Any}, nslots)
             resize!(ci.slotnames, nslots)
             return ccall(:jl_compress_ir, Any, (Any, Any), def, ci)
         else
@@ -438,7 +438,7 @@ function finish(me::InferenceState, interp::AbstractInterpreter)
         empty!(edges)
     end
     if me.src.edges !== nothing
-        append!(s_edges, me.src.edges)
+        append!(s_edges, me.src.edges::Vector)
         me.src.edges = nothing
     end
     # inspect whether our inference had a limited result accuracy,
@@ -447,7 +447,7 @@ function finish(me::InferenceState, interp::AbstractInterpreter)
     limited_ret = me.bestguess isa LimitedAccuracy
     limited_src = false
     if !limited_ret
-        gt = me.src.ssavaluetypes
+        gt = me.src.ssavaluetypes::Vector{Any}
         for j = 1:length(gt)
             gt[j] = gtj = cycle_fix_limited(gt[j], me)
             if gtj isa LimitedAccuracy && me.parent !== nothing
@@ -511,8 +511,9 @@ end
 
 # widen all Const elements in type annotations
 function widen_all_consts!(src::CodeInfo)
-    for i = 1:length(src.ssavaluetypes)
-        src.ssavaluetypes[i] = widenconst(src.ssavaluetypes[i])
+    ssavaluetypes = src.ssavaluetypes::Vector{Any}
+    for i = 1:length(ssavaluetypes)
+        ssavaluetypes[i] = widenconst(ssavaluetypes[i])
     end
 
     for i = 1:length(src.code)
@@ -577,6 +578,7 @@ function record_slot_assign!(sv::InferenceState)
     states = sv.stmt_types
     body = sv.src.code::Vector{Any}
     slottypes = sv.slottypes::Vector{Any}
+    ssavaluetypes = sv.src.ssavaluetypes::Vector{Any}
     for i = 1:length(body)
         expr = body[i]
         st_i = states[i]
@@ -585,7 +587,7 @@ function record_slot_assign!(sv::InferenceState)
             lhs = expr.args[1]
             rhs = expr.args[2]
             if isa(lhs, SlotNumber)
-                vt = widenconst(sv.src.ssavaluetypes[i])
+                vt = widenconst(ssavaluetypes[i])
                 if vt !== Bottom
                     id = slot_id(lhs)
                     otherTy = slottypes[id]
@@ -608,12 +610,11 @@ function type_annotate!(sv::InferenceState, run_optimizer::Bool)
     # (otherwise, we'll perhaps run the optimization passes later, outside of inference)
 
     # remove all unused ssa values
-    gt = sv.src.ssavaluetypes
-    for j = 1:length(gt)
-        if gt[j] === NOT_FOUND
-            gt[j] = Union{}
-        end
-        gt[j] = widenconditional(gt[j])
+    src = sv.src
+    ssavaluetypes = src.ssavaluetypes::Vector{Any}
+    for j = 1:length(ssavaluetypes)
+        t = ssavaluetypes[j]
+        ssavaluetypes[j] = t === NOT_FOUND ? Union{} : widenconditional(t)
     end
 
     # compute the required type for each slot
@@ -626,7 +627,6 @@ function type_annotate!(sv::InferenceState, run_optimizer::Bool)
     # annotate variables load types
     # remove dead code optimization
     # and compute which variables may be used undef
-    src = sv.src
     states = sv.stmt_types
     nargs = sv.nargs
     nslots = length(states[1]::VarTable)
@@ -669,7 +669,7 @@ function type_annotate!(sv::InferenceState, run_optimizer::Bool)
             elseif run_optimizer
                 deleteat!(body, i)
                 deleteat!(states, i)
-                deleteat!(src.ssavaluetypes, i)
+                deleteat!(ssavaluetypes, i)
                 deleteat!(src.codelocs, i)
                 deleteat!(sv.stmt_info, i)
                 nexpr -= 1
diff --git a/base/compiler/typelattice.jl b/base/compiler/typelattice.jl
index 6391d4029b58e..9712e023c7004 100644
--- a/base/compiler/typelattice.jl
+++ b/base/compiler/typelattice.jl
@@ -299,7 +299,7 @@ function smerge(sa::Union{NotFound,VarState}, sb::Union{NotFound,VarState})
 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)))
+@inline schanged(@nospecialize(n), @nospecialize(o)) = (n !== o) && (o === NOT_FOUND || (n !== NOT_FOUND && !issubstate(n::VarState, o::VarState)))
 
 widenconditional(@nospecialize typ) = typ
 function widenconditional(typ::AnyConditional)
@@ -396,7 +396,7 @@ function stupdate1!(state::VarTable, change::StateUpdate)
                 if isa(oldtypetyp, Conditional) && slot_id(oldtypetyp.var) == changeid
                     oldtypetyp = widenconditional(oldtypetyp)
                     if oldtype.typ isa LimitedAccuracy
-                        oldtypetyp = LimitedAccuracy(oldtypetyp, oldtype.typ.causes)
+                        oldtypetyp = LimitedAccuracy(oldtypetyp, (oldtype.typ::LimitedAccuracy).causes)
                     end
                     state[i] = VarState(oldtypetyp, oldtype.undef)
                 end
diff --git a/base/compiler/validation.jl b/base/compiler/validation.jl
index f6b89f8f5cd04..c152dfb9fa6a5 100644
--- a/base/compiler/validation.jl
+++ b/base/compiler/validation.jl
@@ -1,7 +1,7 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
 # Expr head => argument count bounds
-const VALID_EXPR_HEADS = IdDict{Symbol,UnitRange}(
+const VALID_EXPR_HEADS = IdDict{Symbol,UnitRange{Int}}(
     :call => 1:typemax(Int),
     :invoke => 2:typemax(Int),
     :static_parameter => 1:1,
@@ -180,10 +180,11 @@ function validate_code!(errors::Vector{>:InvalidCodeError}, c::CodeInfo, is_top_
     !is_top_level && nslotnames == 0 && push!(errors, InvalidCodeError(EMPTY_SLOTNAMES))
     nslotnames < nslotflags && push!(errors, InvalidCodeError(SLOTFLAGS_MISMATCH, (nslotnames, nslotflags)))
     if c.inferred
-        nssavaluetypes = length(c.ssavaluetypes)
+        nssavaluetypes = length(c.ssavaluetypes::Vector{Any})
         nssavaluetypes < nssavals && push!(errors, InvalidCodeError(SSAVALUETYPES_MISMATCH, (nssavals, nssavaluetypes)))
     else
-        c.ssavaluetypes != nssavals && push!(errors, InvalidCodeError(SSAVALUETYPES_MISMATCH_UNINFERRED, (nssavals, c.ssavaluetypes)))
+        ssavaluetypes = c.ssavaluetypes::Int
+        ssavaluetypes != nssavals && push!(errors, InvalidCodeError(SSAVALUETYPES_MISMATCH_UNINFERRED, (nssavals, ssavaluetypes)))
     end
     return errors
 end
@@ -205,7 +206,7 @@ function validate_code!(errors::Vector{>:InvalidCodeError}, mi::Core.MethodInsta
     else
         m = mi.def::Method
         mnargs = m.nargs
-        n_sig_params = length(Core.Compiler.unwrap_unionall(m.sig).parameters)
+        n_sig_params = length((unwrap_unionall(m.sig)::DataType).parameters)
         if (m.isva ? (n_sig_params < (mnargs - 1)) : (n_sig_params != mnargs))
             push!(errors, InvalidCodeError(SIGNATURE_NARGS_MISMATCH, (m.isva, n_sig_params, mnargs)))
         end