Hervé Brönnimann <hervebronnimann <at> mac.com> writes:
On May 15, 2008, at 10:40 AM, John Moeller wrote:
Fair enough. I think, though, if you're going to try to make sure that the compiler doesn't miss multiplication by 1, you may as well go all the way and add another template parameter to capture N%2, and get rid of the ternary statement:
To be clear, I'm not concerned about optimizing multiplication by 1 for builtin types, of course. But it seems to me that the compiler shouldn't really be able to optimize for user-defined types (what if multiplication isn't inlined, for instance...)
And regardless of whether the type is builtin or not, branching with template parameters will accomplish the same task as letting the compiler decide to inline a ternary statement, except that it will be explicit. There is zero chance of the compiler generating more instructions than are needed (unless inlining breaks down). I know that this ternary statement's condition may be evaluated at compile time, so there is little chance of more than one branch being generated, but why not just make it explicit? (From an aesthetic standpoint, I think branching with a template parameter expresses the recursion very elegantly (two branches, one base condition), and doesn't get in the way at all. Elegance isn't really what matters here, though.) My response wasn't motivated emotionally; I agree with your argument about UDT multiplication (as I did when I wrote my response in the first place). I'm just saying it would be advantageous to follow the process further. -- John Moeller