release mode optimization

Ali Çehreli acehreli at yahoo.com
Thu Jan 10 08:41:19 PST 2013


On 01/09/2013 04:14 PM, Charles Hixson wrote:
> Would the following code:
> for (int i = 1; i < di.count; i++)
> { assert (node.di.entry[i - 1].key < node.di.entry[i].key); }
>
> be optimized away if compiled under -release?

It looks like you can use std.algorithm.isSorted instead:

   http://dlang.org/phobos/std_algorithm.html#isSorted

     assert(isSorted(di));

Or perhaps:

     assert(isSorted(node.di.entry[0 .. di.count]));

That code will disappear in release mode.

Additionally, if the O(N) complexity of that check is not acceptable 
even in non-release mode there is std.range.assumeSorted:

   http://dlang.org/phobos/std_range.html#.assumeSorted

assumeSorted makes very few comparisons so it may miss occasional sort 
issues. Also, it is not really for checking but more for range 
algorithms that require or work better with a sorted range.

Ali


More information about the Digitalmars-d-learn mailing list