Faster iterator for (almost) empty Dict (#44411)

Author: petvana

base/dict.jl

@@ -88,7 +88,7 @@ mutable struct Dict{K,V} <: AbstractDict{K,V}
 
     function Dict{K,V}() where V where K
         n = 16
-        new(zeros(UInt8,n), Vector{K}(undef, n), Vector{V}(undef, n), 0, 0, 0, 1, 0)
+        new(zeros(UInt8,n), Vector{K}(undef, n), Vector{V}(undef, n), 0, 0, 0, n, 0)
     end
     function Dict{K,V}(d::Dict{K,V}) where V where K
         new(copy(d.slots), copy(d.keys), copy(d.vals), d.ndel, d.count, d.age,
@@ -274,7 +274,7 @@ function empty!(h::Dict{K,V}) where V where K
     h.ndel = 0
     h.count = 0
     h.age += 1
-    h.idxfloor = 1
+    h.idxfloor = sz
     return h
 end