On Wed, Aug 7, 2013 at 8:37 AM, Jan Hubicka <hubi...@ucw.cz> wrote: >> Ping? >> >> David >> >> On Sat, Aug 3, 2013 at 12:36 PM, Xinliang David Li <davi...@google.com> >> wrote: >> > Hi, GCC/i386 currently has about 73 boolean parameters/knobs (defined >> > in ix86_tune_features[], indexed by ix86_tune_indices) to perform >> > micro-arch specific performance tuning. However such settings are hard >> > coded (fixed with a given -mtune setting) and is very hard to do >> > performance experiment. >> > >> > The attached patch fixes the problem. The patch introduces a new >> > option -mtune-ctrl=. Its parameter is a comma separated list of >> > feature names to turn on associated features. Feature name can be >> > prefixed by ^ to do the opposite. For instance, >> > >> > -mtune-ctrl=prologue_using_move,epilogue_using_move,^pad_returns >> > >> > tells the compiler to use move instructions in prologue/epilogue >> > (instead of push/pop), and *not* pad return instructions. >> > >> > To facilitate the change, the feature tuning enums defined in i386.h >> > are moved to a new file x86-tune.def and this file can be used to >> > generate both the enums and names of the features. >> > >> > >> > Ok for trunk? > > Yes, this patch seems fine to me (as an undocumented option we should not > be obliged to fix any ices from non-sential combinations of flags and in > fact I do not really know of any). > I wonder if we can't feed initial_ix86_tune_features so we get rid of > two places that needs to be kept in sync when adding new knob?
Good concern -- the initial setting can be put into the def file too to make sure they are always synced. I will do this in a follow up patch. thanks, David > > Honza >> > >> > >> > thanks, >> > >> > David >> > >> > 2013-08-03 Xinliang David Li <davi...@google.com> >> > >> > * config/i386/i386.opt: New option -mtune-ctrl=. >> > * config/i386/x86-tune.def: New file. >> > * config/i386/i386.h: include x86-tune.def. >> > * config/i386/i386.c (ix86_option_override_internal): >> > Parsing -mtune-ctrl= option and set tune features.
