On Thu, Jun 30, 2011 at 12:34 AM, Michael Meissner <meiss...@linux.vnet.ibm.com> wrote: > On the powerpc, switch statements can be expensive, and we would like to be > able to tune the threshold of when the compiler generates if statements > vs. using a table jump operation (and different processors within the powerpc > have different limits). This patch adds a powerpc tuning option to control > this. > > I've done bootstraps and make checks with no regressions. Is this ok to apply > to the trunk? At this time, I am not changing the default value (4). With > the > option, I've seen a few spec 2006 benchmarks run faster, and a few run slower.
Hmm. This hook looks like it could be turned into a --param. In fact it doesn't get whatever context information, so I wonder if any target does something fancy. Richard. > [gcc] > 2011-06-29 Michael Meissner <meiss...@linux.vnet.ibm.com> > > * config/rs6000/rs6000.opt (-mcase-values-threshold): New switch. > > * config/rs6000/rs6000.c (TARGET_CASE_VALUES_THRESHOLD): New > target hook for override choice of when to do jump table vs. if > statements based on -mcase-values-threshold=<n>. > > * doc/invoke.texi (RS/6000 and PowerPC Options): Document > -mcase-values-threshold. > > [gcc/testsuite] > 2011-06-29 Michael Meissner <meiss...@linux.vnet.ibm.com> > > * gcc.target/powerpc/ppc-switch-1.c: New test for > -mcase-values-threshold. > * gcc.target/powerpc/ppc-switch-2.c: Ditto. > > -- > Michael Meissner, IBM > 5 Technology Place Drive, M/S 2757, Westford, MA 01886-3141, USA > meiss...@linux.vnet.ibm.com fax +1 (978) 399-6899 >
