5% more speed to divmod

src/private/bithacks.nim

@@ -44,6 +44,9 @@ proc bit_length*[T: MpUint](n: T): int {.noSideEffect.}=
 
   const maxHalfRepr = n.lo.type.sizeof * 8 - 1
 
+  # Changing the following to an if expression somehow transform the whole ASM to 5 branches
+  # instead of the 4 expected (with the inline ASM from bit_length_impl)
+  # Also there does not seems to be a way to generate a conditional mov
   if n.hi.bit_length == 0:
     n.lo.bit_length
   else:

src/uint_binary_ops.nim

@@ -114,16 +114,11 @@ proc divmod*[T: BaseUint](x, y: T): tuple[quot, rem: T] {.noSideEffect.}=
 
   when x.lo is MpUInt:
     const one = T(lo: getSubType(T)(1))
-    const mpOne = one
   else:
     const one: getSubType(T) = 1
-    const mpOne = T(lo: getSubType(T)(1))
 
-  if y == zero:
+  if unlikely(y.isZero):
     raise newException(DivByZeroError, "You attempted to divide by zero")
-  elif y == mpOne:
-    result.quot = x
-    return
 
   var
     shift = x.bit_length - y.bit_length

src/uint_comparison.nim

@@ -11,3 +11,9 @@ proc `<=`*[T: MpUint](x, y: T): bool {.noSideEffect, noInit, inline.}=
   if x == y:
     return true
   x < y
+
+proc isZero[T: SomeUnsignedInt](n: T): bool {.noSideEffect,inline.} =
+  n == 0.T
+
+proc isZero*(n: MpUint): bool {.noSideEffect,inline.} =
+  n.lo.isZero and n.hi.isZero