On Thu, Oct 5, 2017 at 3:17 PM, Bin Cheng <bin.ch...@arm.com> wrote:
> Hi,
> For now distribution pass only handles the innermost loop. This patch
> extends the pass
> to cover two-level innermost loop nest. It also refactors code in
> pass_loop_distribution::execute
> for better reading. Note I restrict it to 2-level loop nest on purpose
> because of high
> cost in data dependence computation. Some compilation time optimizations
> like reusing
> the data reference finding, data dependence computing, would require a
> rewrite of this
> pass like the proposed loop interchange implementation. But that's another
> task.
>
> This patch introduces a temporary TODO for loop nest builtin partition which
> is covered
> by next two patches.
>
> With this patch, kernel loop in bwaves now can be distributed, thus exposed
> for further
> interchange. This patch adds new test for matrix multiplication, as well as
> adjusts
> test strings of existing tests.
> Bootstrap and test in patch set on x86_64 and AArch64, is it OK?
@ -714,9 +719,11 @@ ssa_name_has_uses_outside_loop_p (tree def, loop_p loop)
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, def)
{
- gimple *use_stmt = USE_STMT (use_p);
- if (!is_gimple_debug (use_stmt)
- && loop != loop_containing_stmt (use_stmt))
+ if (is_gimple_debug (USE_STMT (use_p)))
+ continue;
+
+ basic_block use_bb = gimple_bb (USE_STMT (use_p));
+ if (use_bb == NULL || !flow_bb_inside_loop_p (loop, use_bb))
return true;
use_bb should never be NULL.
+ /* Don't support loop nest distribution under runtime alias check
+ since it's not likely to enable many vectorization opportunities. */
+ if (loop->inner)
+ {
+ merge_dep_scc_partitions (rdg, &partitions, false);
+ }
extra {}
+ /* Support loop nest distribution enclosing current innermost loop.
+ For the moment, we only support the innermost two-level loop nest. */
+ if (flag_tree_loop_distribution
+ && outer->num > 0 && outer->inner == loop && loop->next == NULL
The canonical check for is-this-non-root is loop_outer (outer) instead
of outer->num > 0.
+ && single_exit (outer)
not sure how exits are counted but if the inner loop exits also the
outer loop do
we correctly handle/reject this case?
- if (nb_generated_loops + nb_generated_calls > 0)
- {
- changed = true;
- dump_printf_loc (MSG_OPTIMIZED_LOCATIONS,
- loc, "Loop %d distributed: split to %d loops "
- "and %d library calls.\n",
- num, nb_generated_loops, nb_generated_calls);
+ if (nb_generated_loops + nb_generated_calls > 0)
+ {
+ changed = true;
+ dump_printf_loc (MSG_OPTIMIZED_LOCATIONS,
+ loc, "Loop%s %d distributed: split to %d loops "
+ "and %d library calls.\n",
+ loop_nest_p ? " nest" : "", loop->num,
+ nb_generated_loops, nb_generated_call
...
can you adjust the printfs to say "loop nest distributed" in case we distributed
a nest?
Can you rewrite the iteration over the nest so it would theoretically support
arbitrary deep perfect nests? Thus simply initialize loop_nest_p less
cleverly...
Otherwise looks ok to me.
Thanks,
Richard.
> Thanks,
> bin
> 2017-10-04 Bin Cheng <bin.ch...@arm.com>
>
> * tree-loop-distribution.c: Adjust the general comment.
> (NUM_PARTITION_THRESHOLD): New macro.
> (ssa_name_has_uses_outside_loop_p): Support loop nest distribution.
> (classify_partition): Skip builtin pattern of loop nest's inner loop.
> (merge_dep_scc_partitions): New parameter ignore_alias_p and use it
> in call to build_partition_graph.
> (finalize_partitions): New parameter. Make loop distribution more
> conservative by fusing more partitions.
> (distribute_loop): Don't do runtime alias check in case of loop nest
> distribution.
> (find_seed_stmts_for_distribution): New function.
> (pass_loop_distribution::execute): Refactor code finding seed stmts
> into above function. Support loop nest distribution for two-level
> innermost loop nest. Adjust dump information.
>
> gcc/testsuite/ChangeLog
> 2017-10-04 Bin Cheng <bin.ch...@arm.com>
>
> * gcc.dg/tree-ssa/ldist-7.c: Adjust test string.
> * gcc.dg/tree-ssa/ldist-16.c: Ditto.
> * gcc.dg/tree-ssa/ldist-25.c: Ditto.
> * gcc.dg/tree-ssa/ldist-33.c: Ditto.
