On Thu, 2005-08-25 at 02:42 -0400, James Morrison wrote: > Hey, > > I'm going to do more testing on this, but it seems this patch reduces the > number of DOM iterations from the number of else if statements in pr19097 to > 2 DOM iterations. Certainly any time we can optimize more of the comparisons in a smaller number of iterations, it's going to be a compile-time win.
> This is a massive savings and the savings if from > calling fold_build2 (cond_code, boolean_type_node, op0, op1) in > thread_across_edge since the folded expression is now saved for the rest of > the iteration where the folded expression wasn't before. Huh? I don't follow this explanation. Nor after a quick read of the code do I see how you've made any real change here. Both before and after your change we still fold the condition and store the result in cached_lhs. Also note that both cached_lhs and the dummy condition are only valid for a single call to thread_across_edge -- so if you're saving a value from one call and expecting it to be valid across another call (from the standpoint of the correctness of the target program), then it's clearly wrong. Jeff
