improve effects of objectid and getindex(::Dict)

base/dict.jl

@@ -258,11 +258,12 @@ function empty!(h::Dict{K,V}) where V where K
 end
 
 # get the index where a key is stored, or -1 if not present
-function ht_keyindex(h::Dict{K,V}, key) where V where K
+@assume_effects :terminates_locally function ht_keyindex(h::Dict{K,V}, key) where V where K
     isempty(h) && return -1
     sz = length(h.keys)
     iter = 0
     maxprobe = h.maxprobe
+    maxprobe < sz || throw(AssertionError()) # This error will never trigger, but is needed for terminates_locally to be valid
     index, sh = hashindex(key, sz)
     keys = h.keys
 

base/reflection.jl

@@ -334,17 +334,6 @@ macro locals()
     return Expr(:locals)
 end
 
-"""
-    objectid(x) -> UInt
-
-Get a hash value for `x` based on object identity.
-
-If `x === y` then `objectid(x) == objectid(y)`, and usually when `x !== y`, `objectid(x) != objectid(y)`.
-
-See also [`hash`](@ref), [`IdDict`](@ref).
-"""
-objectid(@nospecialize(x)) = ccall(:jl_object_id, UInt, (Any,), x)
-
 # concrete datatype predicates
 
 datatype_fieldtypes(x::DataType) = ccall(:jl_get_fieldtypes, Core.SimpleVector, (Any,), x)
@@ -600,6 +589,28 @@ Return `true` if `x` is an instance of an [`isbitstype`](@ref) type.
 """
 isbits(@nospecialize x) = isbitstype(typeof(x))
 
+"""
+    objectid(x) -> UInt
+
+Get a hash value for `x` based on object identity.
+
+If `x === y` then `objectid(x) == objectid(y)`, and usually when `x !== y`, `objectid(x) != objectid(y)`.
+
+See also [`hash`](@ref), [`IdDict`](@ref).
+"""
+function objectid(x)
+    # objectid is foldable iff it isn't a pointer.
+    if isidentityfree(typeof(x))
+        return _foldable_objectid(x)
+    end
+    return _objectid(x)
+end
+function _foldable_objectid(@nospecialize(x))
+    @_foldable_meta
+    _objectid(x)
+end
+_objectid(@nospecialize(x)) = ccall(:jl_object_id, UInt, (Any,), x)
+
 """
     isdispatchtuple(T)
 

test/dict.jl

@@ -1363,3 +1363,9 @@ end
     sizehint!(d, 10)
     @test length(d.slots) < 100
 end
+
+# getindex is effect free and nothrow but not consistent
+for T in (String, Module, Symbol, Int, Float64)
+    @test Core.Compiler.is_effect_free(Base.infer_effects(getindex, (Dict{T, BigInt},T)))
+    @test Core.Compiler.is_terminates(Base.infer_effects(getindex, (Dict{T, BigInt},T)))
+end

test/reflection.jl

@@ -1035,6 +1035,12 @@ ambig_effects_test(a, b) = 1
     @test Base.infer_effects(===, (Any,Any)) |> Core.Compiler.is_foldable_nothrow
     @test (Base.infer_effects(setfield!, ()); true) # `builtin_effects` shouldn't throw on empty `argtypes`
     @test (Base.infer_effects(Core.Intrinsics.arraylen, ()); true) # `intrinsic_effects` shouldn't throw on empty `argtypes`
+    for T in (Int, String, Symbol, Some{Int}, Some{String}, Some{Symbol}, Some{Some{Int}}, Some{Some{String}}, Some{Some{Symbol}})
+         @test Core.Compiler.is_foldable(Base.infer_effects(hash, (T,)))
+    end
+    # objectid for datatypes is inconsistant for types that have unbound type parameters.
+    @test !Core.Compiler.is_consistent(Base.infer_effects(hash, (DataType,)))
+    @test !Core.Compiler.is_consistent(Base.infer_effects(hash, (Tuple{Vector{Int}},)))
 end
 
 @test Base._methods_by_ftype(Tuple{}, -1, Base.get_world_counter()) == Any[]