On Tue, Jun 20, 2017 at 11:18 AM, Bin.Cheng <amker.ch...@gmail.com> wrote: > On Fri, Jun 16, 2017 at 11:10 AM, Richard Biener > <richard.guent...@gmail.com> wrote: >> On Mon, Jun 12, 2017 at 7:03 PM, Bin Cheng <bin.ch...@arm.com> wrote: >>> Hi, >>> This patch checks and records if partition can be executed in parallel by >>> looking if there exists data dependence cycles. The information is needed >>> for distribution because the idea is to distribute parallel type partitions >>> away from sequential ones. I believe current distribution doesn't work >>> very well because it does blind distribution/fusion. >>> Bootstrap and test on x86_64 and AArch64. Is it OK? >> >> + /* In case of no data dependence. */ >> + if (DDR_ARE_DEPENDENT (ddr) == chrec_known) >> + return false; >> + /* Or the data dependence can be resolved by compilation time alias >> + check. */ >> + else if (!alias_sets_conflict_p (get_alias_set (DR_REF (dr1)), >> + get_alias_set (DR_REF (dr2)))) >> + return false; >> >> dependence analysis should use TBAA already, in which cases do you need this? >> It seems to fall foul of the easy mistake of not honoring GCCs memory model >> as well ... see dr_may_alias_p. > I see. Patch updated with this branch removed. > >> >> + /* Further check if any data dependence prevents us from executing the >> + partition parallelly. */ >> + EXECUTE_IF_SET_IN_BITMAP (partition->reads, 0, i, bi) >> + { >> + dr1 = (*datarefs_vec)[i]; >> + EXECUTE_IF_SET_IN_BITMAP (partition->writes, 0, j, bj) >> + { >> >> what about write-write dependences? >> >> + EXECUTE_IF_SET_IN_BITMAP (partition->reads, 0, i, bi) >> + { >> + dr1 = (*datarefs_vec)[i]; >> + EXECUTE_IF_SET_IN_BITMAP (partition->writes, i + 1, j, bj) >> + { >> + dr2 = (*datarefs_vec)[j]; >> + /* Partition can only be executed sequentially if there is any >> + data dependence cycle. */ >> >> exact copy of the loop nest follows?! Maybe you meant to iterate >> over writes in the first loop. > Yes, this is a copy-paste typo. Patch is also simplified because > read/write are recorded together now. Is it OK?
Ok. Thanks, Richard. > Thanks, > bin > 2017-06-07 Bin Cheng <bin.ch...@arm.com> > > * tree-loop-distribution.c (enum partition_type): New. > (struct partition): New field type. > (partition_merge_into): Update partition type. > (data_dep_in_cycle_p): New function. > (build_rdg_partition_for_vertex): Compute partition type. > (rdg_build_partitions): Dump partition type.