On Fri, Mar 23, 2012 at 3:29 PM, Andi Kleen <a...@firstfloor.org> wrote: > Easwaran Raman <era...@google.com> writes: > >> Some more background on this patch: Right now, while the execution >> counts of different case labels of a switch statement are obtained >> during profile collection, they are not propagated to RTL. Instead, >> counts are regenerated at the RTL level using static heuristics that >> tend to weigh branches equally which can cause poor optimization of >> hot code. This patch ensures that the counts collected during profile >> collection are correctly propagated allowing hot code to be better >> optimized by RTL optimizations. Patch tested on x86_64. > > I think your patch doesn't use the probably to weight the decision > tree for non tablejump, right? I looked at this some time ago, > but the patch always had problems.
Do you mean use the weights to decide the shape of the binary tree (similar to COST_TABLE heuristic)? I am planning to send a separate patch for that. This one just makes sure that the profile counts are propagated correctly. So you will still have a situation where a branch corresponding to an infrequently executed case dominates a frequently executed case, but the BB of the cases gets the right profile weight. - Easwaran > -Andi > > -- > a...@linux.intel.com -- Speaking for myself only
