Re: [PATCH PR82726/PR70754][2/2]New fix by finding correct root reference in combined chains

[Richard Biener <richard dot guenther at gmail dot com>]

On Fri, Nov 3, 2017 at 1:40 PM, Bin Cheng <Bin.Cheng@arm.com> wrote:
> Hi,
> As described in message of previous patch:
>
> This patch set fixes both PRs in the opposite way: Instead of find dominance
> insertion position for root reference, we resort zero-distance references of
> combined chain by their position information so that new root reference must
> dominate others.  This should be more efficient because we avoid function call
> to stmt_dominates_stmt_p.
> Bootstrap and test on x86_64 and AArch64 in patch set.  Is it OK?

+/* { dg-additional-options "-mavx2" { target avx2_runtime } } */

you don't need avx2_runtime for -mavx2 so please instead use
{ target { x86_64-*-* i?86-*-* } }

+#include <map>
+#define INCLUDE_ALGORITHM /* std::sort */

can you please use GCCs own hash_map?  Btw...

+  /* Setup UID for all statements in dominance order.  */
+  std::map<gimple *, int> stmts_map;
+  basic_block *bbs = get_loop_body_in_dom_order (loop);
+  for (i = 0; i < loop->num_nodes; i++)
+    {
+      int uid = 0;
+      basic_block bb = bbs[i];
+
+      for (gimple_stmt_iterator bsi = gsi_start_phis (bb); !gsi_end_p (bsi);
+          gsi_next (&bsi))
+       {
+         gimple *stmt = gsi_stmt (bsi);
+         if (!virtual_operand_p (gimple_phi_result (as_a<gphi *> (stmt))))
+           stmts_map[stmt] = uid;

why don't you use gimple_[set_]uid ()?  Given you do a dominance check
you don't even need to do this in dominance order - usually passes just
number UIDs in all relevant BBs.  There is a helper for that as well,
renumber_gimple_stmt_uids_in_blocks which can be used on
the get_loop_body result.

+      /* Sort all ZERO distance references by position.  */
+      std::sort (&ch1->refs[0], &ch1->refs[0] + j, order_drefs_by_pos);
+

given ch1->refs is a vec you can use the new vec::qsort_block you added
instead of including algorithm and using std::sort.

Richard.

> Thanks,
> bin
> 2017-11-02  Bin Cheng  <bin.cheng@arm.com>
>
>         PR tree-optimization/82726
>         PR tree-optimization/70754
>         * tree-predcom.c (<map>, INCLUDE_ALGORITHM): New headers.
>         (order_drefs_by_pos): New function.
>         (combine_chains): Move code setting has_max_use_after to...
>         (try_combine_chains): ...here.  New parameter.  Sort combined chains
>         according to position information.
>         (tree_predictive_commoning_loop): Update call to above function.
>         (update_pos_for_combined_chains, pcom_stmt_dominates_stmt_p): New.
>
> gcc/testsuite
> 2017-11-02  Bin Cheng  <bin.cheng@arm.com>
>
>         PR tree-optimization/82726
>         * gcc.dg/tree-ssa/pr82726.c: New test.