avoid expensive runtime div in parse (JuliaLang#29892)

tkf · Nov 21, 2018 · 22afe9b · 22afe9b
1 parent a2eb705
commit 22afe9b
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/base/parse.jl b/base/parse.jl
@@ -107,7 +107,10 @@ function tryparse_internal(::Type{T}, s::AbstractString, startpos::Int, endpos::
  end
 
  base = convert(T, base)
- m::T = div(typemax(T) - base + 1, base)
+ # Special case the common cases of base being 10 or 16 to avoid expensive runtime div
+ m::T = base == 10 ? div(typemax(T) - T(9), T(10)) :
+ base == 16 ? div(typemax(T) - T(15), T(16)) :
+ div(typemax(T) - base + 1, base)
  n::T = 0
  a::Int = base <= 36 ? 10 : 36
  _0 = UInt32('0')