inference: accelerate type-limits under wide-recursion (#31734)

when we hit union-splitting, we need to ensure type limits are very aggressive
and preferably also independent of the height of the recursion chain

fix #31572

(cherry picked from commit 32b091b)

base/compiler/abstractinterpretation.jl

@@ -63,6 +63,7 @@ function abstract_call_gf_by_type(@nospecialize(f), argtypes::Vector{Any}, @nosp
     nonbot = 0  # the index of the only non-Bottom inference result if > 0
     seen = 0    # number of signatures actually inferred
     istoplevel = sv.linfo.def isa Module
+    multiple_matches = napplicable > 1
     for i in 1:napplicable
         match = applicable[i]::SimpleVector
         method = match[3]::Method
@@ -80,7 +81,7 @@ function abstract_call_gf_by_type(@nospecialize(f), argtypes::Vector{Any}, @nosp
         if splitunions
             splitsigs = switchtupleunion(sig)
             for sig_n in splitsigs
-                rt, edgecycle1, edge = abstract_call_method(method, sig_n, svec(), sv)
+                rt, edgecycle1, edge = abstract_call_method(method, sig_n, svec(), multiple_matches, sv)
                 if edge !== nothing
                     push!(edges, edge)
                 end
@@ -89,7 +90,7 @@ function abstract_call_gf_by_type(@nospecialize(f), argtypes::Vector{Any}, @nosp
                 this_rt === Any && break
             end
         else
-            this_rt, edgecycle1, edge = abstract_call_method(method, sig, match[2]::SimpleVector, sv)
+            this_rt, edgecycle1, edge = abstract_call_method(method, sig, match[2]::SimpleVector, multiple_matches, sv)
             edgecycle |= edgecycle1::Bool
             if edge !== nothing
                 push!(edges, edge)
@@ -227,7 +228,7 @@ function abstract_call_method_with_const_args(@nospecialize(rettype), @nospecial
     return result
 end
 
-function abstract_call_method(method::Method, @nospecialize(sig), sparams::SimpleVector, sv::InferenceState)
+function abstract_call_method(method::Method, @nospecialize(sig), sparams::SimpleVector, hardlimit::Bool, sv::InferenceState)
     if method.name === :depwarn && isdefined(Main, :Base) && method.module === Main.Base
         return Any, false, nothing
     end
@@ -266,30 +267,36 @@ function abstract_call_method(method::Method, @nospecialize(sig), sparams::Simpl
             inf_method2 = infstate.src.method_for_inference_limit_heuristics # limit only if user token match
             inf_method2 isa Method || (inf_method2 = nothing) # Union{Method, Nothing}
             if topmost === nothing && method2 === inf_method2
-                # inspect the parent of this edge,
-                # to see if they are the same Method as sv
-                # in which case we'll need to ensure it is convergent
-                # otherwise, we don't
-                for parent in infstate.callers_in_cycle
-                    # check in the cycle list first
-                    # all items in here are mutual parents of all others
-                    parent_method2 = parent.src.method_for_inference_limit_heuristics # limit only if user token match
-                    parent_method2 isa Method || (parent_method2 = nothing) # Union{Method, Nothing}
-                    if parent.linfo.def === sv.linfo.def && sv_method2 === parent_method2
-                        topmost = infstate
-                        edgecycle = true
-                        break
-                    end
-                end
-                let parent = infstate.parent
-                    # then check the parent link
-                    if topmost === nothing && parent !== nothing
-                        parent = parent::InferenceState
+                if hardlimit
+                    topmost = infstate
+                    edgecycle = true
+                else
+                    # if this is a soft limit,
+                    # also inspect the parent of this edge,
+                    # to see if they are the same Method as sv
+                    # in which case we'll need to ensure it is convergent
+                    # otherwise, we don't
+                    for parent in infstate.callers_in_cycle
+                        # check in the cycle list first
+                        # all items in here are mutual parents of all others
                         parent_method2 = parent.src.method_for_inference_limit_heuristics # limit only if user token match
                         parent_method2 isa Method || (parent_method2 = nothing) # Union{Method, Nothing}
-                        if (parent.cached || parent.limited) && parent.linfo.def === sv.linfo.def && sv_method2 === parent_method2
+                        if parent.linfo.def === sv.linfo.def && sv_method2 === parent_method2
                             topmost = infstate
                             edgecycle = true
+                            break
+                        end
+                    end
+                    let parent = infstate.parent
+                        # then check the parent link
+                        if topmost === nothing && parent !== nothing
+                            parent = parent::InferenceState
+                            parent_method2 = parent.src.method_for_inference_limit_heuristics # limit only if user token match
+                            parent_method2 isa Method || (parent_method2 = nothing) # Union{Method, Nothing}
+                            if (parent.cached || parent.limited) && parent.linfo.def === sv.linfo.def && sv_method2 === parent_method2
+                                topmost = infstate
+                                edgecycle = true
+                            end
                         end
                     end
                 end
@@ -321,7 +328,7 @@ function abstract_call_method(method::Method, @nospecialize(sig), sparams::Simpl
             comparison = method.sig
         end
         # see if the type is actually too big (relative to the caller), and limit it if required
-        newsig = limit_type_size(sig, comparison, sv.linfo.specTypes, sv.params.TUPLE_COMPLEXITY_LIMIT_DEPTH, spec_len)
+        newsig = limit_type_size(sig, comparison, hardlimit ? comparison : sv.linfo.specTypes, sv.params.TUPLE_COMPLEXITY_LIMIT_DEPTH, spec_len)
 
         if newsig !== sig
             # continue inference, but note that we've limited parameter complexity

test/compiler/inference.jl

@@ -1071,13 +1071,13 @@ copy_dims_out(out) = ()
 copy_dims_out(out, dim::Int, tail...) =  copy_dims_out((out..., dim), tail...)
 copy_dims_out(out, dim::Colon, tail...) = copy_dims_out((out..., dim), tail...)
 @test Base.return_types(copy_dims_out, (Tuple{}, Vararg{Union{Int,Colon}})) == Any[Tuple{}, Tuple{}, Tuple{}]
-@test all(m -> 20 < count_specializations(m) < 45, methods(copy_dims_out))
+@test all(m -> 4 < count_specializations(m) < 15, methods(copy_dims_out)) # currently about 5
 
 copy_dims_pair(out) = ()
 copy_dims_pair(out, dim::Int, tail...) =  copy_dims_pair(out => dim, tail...)
 copy_dims_pair(out, dim::Colon, tail...) = copy_dims_pair(out => dim, tail...)
 @test Base.return_types(copy_dims_pair, (Tuple{}, Vararg{Union{Int,Colon}})) == Any[Tuple{}, Tuple{}, Tuple{}]
-@test all(m -> 10 < count_specializations(m) < 35, methods(copy_dims_pair))
+@test all(m -> 5 < count_specializations(m) < 15, methods(copy_dims_pair)) # currently about 7
 
 @test isdefined_tfunc(typeof(NamedTuple()), Const(0)) === Const(false)
 @test isdefined_tfunc(typeof(NamedTuple()), Const(1)) === Const(false)
@@ -2369,3 +2369,40 @@ function gen_nodes(qty::Integer) :: AbstractNode
 end
 end
 @test count(==('}'), string(I31663.gen_nodes(50))) == 1275
+
+# issue #31572
+struct MixedKeyDict{T<:Tuple} #<: AbstractDict{Any,Any}
+    dicts::T
+end
+Base.merge(f::Function, d::MixedKeyDict, others::MixedKeyDict...) = _merge(f, (), d.dicts, (d->d.dicts).(others)...)
+Base.merge(f, d::MixedKeyDict, others::MixedKeyDict...) = _merge(f, (), d.dicts, (d->d.dicts).(others)...)
+function _merge(f, res, d, others...)
+    ofsametype, remaining = _alloftype(Base.heads(d), ((),), others...)
+    return _merge(f, (res..., merge(f, ofsametype...)), Base.tail(d), remaining...)
+end
+_merge(f, res, ::Tuple{}, others...) = _merge(f, res, others...)
+_merge(f, res, d) = MixedKeyDict((res..., d...))
+_merge(f, res, ::Tuple{}) = MixedKeyDict(res)
+function _alloftype(ofdesiredtype::Tuple{Vararg{D}}, accumulated, d::Tuple{D,Vararg}, others...) where D
+    return _alloftype((ofdesiredtype..., first(d)),
+                      (Base.front(accumulated)..., (last(accumulated)..., Base.tail(d)...), ()),
+                      others...)
+end
+function _alloftype(ofdesiredtype, accumulated, d, others...)
+    return _alloftype(ofdesiredtype,
+                      (Base.front(accumulated)..., (last(accumulated)..., first(d))),
+                      Base.tail(d), others...)
+end
+function _alloftype(ofdesiredtype, accumulated, ::Tuple{}, others...)
+    return _alloftype(ofdesiredtype,
+                      (accumulated..., ()),
+                      others...)
+end
+_alloftype(ofdesiredtype, accumulated) = ofdesiredtype, Base.front(accumulated)
+let
+    d = MixedKeyDict((Dict(1 => 3), Dict(4. => 2)))
+    e = MixedKeyDict((Dict(1 => 7), Dict(5. => 9)))
+    @test merge(+, d, e).dicts == (Dict(1 => 10), Dict(4.0 => 2, 5.0 => 9))
+    f = MixedKeyDict((Dict(2 => 7), Dict(5. => 11)))
+    @test merge(+, d, e, f).dicts == (Dict(1 => 10, 2 => 7), Dict(4.0 => 2, 5.0 => 20))
+end