On 12/14/2014 02:18 PM, Mark Wielaard wrote: > This finally adds bounds checking to get_[us]leb128 (with two exceptions, > see below). The performance results are a little puzzling, so I hope > Josh can take a look how things are for him. > > On one system, with 3.10.0-123.13.1.el7.x86_64, varlocs -k slows down: > 0.160: 53.65 > master: 52.24 > mjw/pending: 56.35 > > But on another, with 3.17.4-301.fc21.x86_64, varlocs -k speeds up: > 0.160: 69.41 > master: 69.03 > mjw/pending: 68.29 > > Output is the same between versions for each system.
These are probably different compilers too, right? So I suspect the newer compiler just noticed an optimization opportunity. AFAICT, the change to __libdw_form_val_len's parameters, pending commit 1a069eb7ae22, makes the bulk of the difference. But it does seem to be a bit faster still in the leb128 commit 4f6de27c6043 -- curious!
