another improvement to static parameter precision (#31001)

JuliaLang · Feb 9, 2019 · 89d64c6 · 89d64c6
1 parent 6e552e7
commit 89d64c6
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Showing 2 changed files with 38 additions and 31 deletions.
diff --git a/base/compiler/inferencestate.jl b/base/compiler/inferencestate.jl
@@ -136,43 +136,49 @@ function sptypes_from_meth_instance(linfo::MethodInstance)
     for i = 1:length(sp)
         v = sp[i]
         if v isa TypeVar
-            ub = v.ub
-            while ub isa TypeVar
-                ub = ub.ub
+            fromArg = 0
+            # if this parameter came from arg::Type{T}, then `arg` is more precise than
+            # Type{T} where lb<:T<:ub
+            sig = linfo.def.sig
+            temp = sig
+            for j = 1:i-1
+                temp = temp.body
             end
-            if has_free_typevars(ub)
-                ub = Any
+            Pi = temp.var
+            while temp isa UnionAll
+                temp = temp.body
             end
-            lb = v.lb
-            while lb isa TypeVar
-                lb = lb.lb
-            end
-            if has_free_typevars(lb)
-                lb = Bottom
+            sigtypes = temp.parameters
+            for j = 1:length(sigtypes)
+                tj = sigtypes[j]
+                if isType(tj) && tj.parameters[1] === Pi
+                    fromArg = j
+                    break
+                end
             end
-            if Any <: ub && lb <: Bottom
-                ty = Any
-                # if this parameter came from arg::Type{T}, we know that T::Type
-                sig = linfo.def.sig
-                temp = sig
-                for j = 1:i-1
-                    temp = temp.body
+            if fromArg > 0
+                ty = fieldtype(linfo.specTypes, fromArg)
+            else
+                ub = v.ub
+                while ub isa TypeVar
+                    ub = ub.ub
                 end
-                Pi = temp.var
-                while temp isa UnionAll
-                    temp = temp.body
+                if has_free_typevars(ub)
+                    ub = Any
                 end
-                sigtypes = temp.parameters
-                for j = 1:length(sigtypes)
-                    tj = sigtypes[j]
-                    if isType(tj) && tj.parameters[1] === Pi
-                        ty = Type
-                        break
-                    end
+                lb = v.lb
+                while lb isa TypeVar
+                    lb = lb.lb
+                end
+                if has_free_typevars(lb)
+                    lb = Bottom
+                end
+                if Any <: ub && lb <: Bottom
+                    ty = Any
+                else
+                    tv = TypeVar(v.name, lb, ub)
+                    ty = UnionAll(tv, Type{tv})
                 end
-            else
-                tv = TypeVar(v.name, lb, ub)
-                ty = UnionAll(tv, Type{tv})
             end
         else
             ty = Const(v)

diff --git a/test/compiler/inference.jl b/test/compiler/inference.jl
@@ -2216,3 +2216,4 @@ _call_rttf_test() = Core.Compiler.return_type(_rttf_test, Tuple{Any})
 
 f_with_Type_arg(::Type{T}) where {T} = T
 @test Base.return_types(f_with_Type_arg, (Any,)) == Any[Type]
+@test Base.return_types(f_with_Type_arg, (Type{Vector{T}} where T,)) == Any[Type{Vector{T}} where T]
Original file line number	Diff line number	Diff line change
Expand Up		@@ -2216,3 +2216,4 @@ _call_rttf_test() = Core.Compiler.return_type(_rttf_test, Tuple{Any})

		f_with_Type_arg(::Type{T}) where {T} = T
		@test Base.return_types(f_with_Type_arg, (Any,)) == Any[Type]
		@test Base.return_types(f_with_Type_arg, (Type{Vector{T}} where T,)) == Any[Type{Vector{T}} where T]