[PATCH, SMS 2/2] Support instructions with REG_INC_NOTE (second try)

[Revital Eres]

Hello,

This patch extends the implementation to support instructions with
REG_INC notes.
It addresses the comments from the previous submission:
http://gcc.gnu.org/ml/gcc-patches/2011-08/msg01299.html.

btw, regarding your previous question about the usage of the address
register been auto inc, apparently it can be used as follows:

insn 1) def1 = MEM [ pre_dec (addr) ]
out edges: [1 -(T,2,1)-> 1]  [1 -(T,2,0)-> 2]
in edges: [1 -(T,2,1)-> 1]  [2 -(T,2,1)-> 1]  [2 -(A,0,1)->1]

insn 2) MEM [ addr + 3 ] = def1
out edges:  [2 -(T,2,1)-> 1]  [2 -(A,0,1)->1]
in edges: [1 -(T,2,0)-> 2]

Reg-moves were not created for the address when testing on ppc.

Tested and bootstrap with patch 1 on ppc64-redhat-linux
enabling SMS on loops with SC 1. On arm-linux-gnueabi bootstrap
c on top of the set of patches that support do-loop pattern
(http://gcc.gnu.org/ml/gcc-patches/2011-07/msg01807.html) which solves
the bootstrap failure on ARM with SMS flags.

OK for mainline?

Thanks,
Revital


        * ddg.c (autoinc_var_is_used_p): New function.
        (create_ddg_dep_from_intra_loop_link,
        add_cross_iteration_register_deps): Call it.
        * modulo-sched.c (sms_schedule): Handle instructions with REG_INC.
-------------- next part --------------
Index: ddg.c
===================================================================
--- ddg.c	(revision 179138)
+++ ddg.c	(working copy)
@@ -145,6 +145,23 @@ mem_access_insn_p (rtx insn)
   return rtx_mem_access_p (PATTERN (insn));
 }
 
+/* Return true if DEF_INSN contains address been auto-inc or auto-dec
+   which is used in USE_INSN.  Otherwise return false.  The result is
+   been used to decide whether to remove the edge between def_insn and
+   use_insn when -fmodulo-sched-allow-regmoves is set.  */
+static bool
+autoinc_var_is_used_p (rtx def_insn, rtx use_insn)
+{
+  rtx note;
+
+  for (note = REG_NOTES (def_insn); note; note = XEXP (note, 1))
+    if (REG_NOTE_KIND (note) == REG_INC
+	&& reg_referenced_p (XEXP (note, 0), PATTERN (use_insn)))
+      return true;
+
+  return false;
+}
+
 /* Computes the dependence parameters (latency, distance etc.), creates
    a ddg_edge and adds it to the given DDG.  */
 static void
@@ -173,10 +190,15 @@ create_ddg_dep_from_intra_loop_link (ddg
      compensate for that by generating reg-moves based on the life-range
      analysis.  The anti-deps that will be deleted are the ones which
      have true-deps edges in the opposite direction (in other words
-     the kernel has only one def of the relevant register).  TODO:
-     support the removal of all anti-deps edges, i.e. including those
+     the kernel has only one def of the relevant register).
+     If the address that is been auto-inc or auto-dec in DEST_NODE
+     is used in SRC_NODE then do not remove the edge to make sure
+     reg-moves will not be created for this address.  
+     TODO: support the removal of all anti-deps edges, i.e. including those
      whose register has multiple defs in the loop.  */
-  if (flag_modulo_sched_allow_regmoves && (t == ANTI_DEP && dt == REG_DEP))
+  if (flag_modulo_sched_allow_regmoves 
+      && (t == ANTI_DEP && dt == REG_DEP)
+      && !autoinc_var_is_used_p (dest_node->insn, src_node->insn))
     {
       rtx set;
 
@@ -302,10 +324,14 @@ add_cross_iteration_register_deps (ddg_p
 	  gcc_assert (first_def_node);
 
          /* Always create the edge if the use node is a branch in
-            order to prevent the creation of reg-moves.  */
+            order to prevent the creation of reg-moves.  
+            If the address that is been auto-inc or auto-dec in LAST_DEF
+            is used in USE_INSN then do not remove the edge to make sure
+            reg-moves will not be created for that address.  */
           if (DF_REF_ID (last_def) != DF_REF_ID (first_def)
               || !flag_modulo_sched_allow_regmoves
-	      || JUMP_P (use_node->insn))
+	      || JUMP_P (use_node->insn)
+              || autoinc_var_is_used_p (DF_REF_INSN (last_def), use_insn))
             create_ddg_dep_no_link (g, use_node, first_def_node, ANTI_DEP,
                                     REG_DEP, 1);
 
Index: modulo-sched.c
===================================================================
--- modulo-sched.c	(revision 179138)
+++ modulo-sched.c	(working copy)
@@ -1266,12 +1271,10 @@ sms_schedule (void)
 	continue;
       }
 
-      /* Don't handle BBs with calls or barriers or auto-increment insns 
-	 (to avoid creating invalid reg-moves for the auto-increment insns),
+      /* Don't handle BBs with calls or barriers
 	 or !single_set with the exception of instructions that include
 	 count_reg---these instructions are part of the control part
 	 that do-loop recognizes.
-         ??? Should handle auto-increment insns.
          ??? Should handle insns defining subregs.  */
      for (insn = head; insn != NEXT_INSN (tail); insn = NEXT_INSN (insn))
       {
@@ -1282,7 +1285,6 @@ sms_schedule (void)
             || (NONDEBUG_INSN_P (insn) && !JUMP_P (insn)
                 && !single_set (insn) && GET_CODE (PATTERN (insn)) != USE
                 && !reg_mentioned_p (count_reg, insn))
-            || (FIND_REG_INC_NOTE (insn, NULL_RTX) != 0)
             || (INSN_P (insn) && (set = single_set (insn))
                 && GET_CODE (SET_DEST (set)) == SUBREG))
         break;
@@ -1296,8 +1298,6 @@ sms_schedule (void)
 		fprintf (dump_file, "SMS loop-with-call\n");
 	      else if (BARRIER_P (insn))
 		fprintf (dump_file, "SMS loop-with-barrier\n");
-              else if (FIND_REG_INC_NOTE (insn, NULL_RTX) != 0)
-                fprintf (dump_file, "SMS reg inc\n");
               else if ((NONDEBUG_INSN_P (insn) && !JUMP_P (insn)
                 && !single_set (insn) && GET_CODE (PATTERN (insn)) != USE))
                 fprintf (dump_file, "SMS loop-with-not-single-set\n");