Track arguments pointing to local or readonly memory in ipa-fnsummary

this patch implement tracking wehther argument points to readonly memory. This
is is useful for ipa-modref as well as for inline heuristics.  It is desirable
to inline functions that dereference pointers to local variables in order
to support SRA.  We always did the oposite heuristics (guessing that the
dereferences will be optimized out with 50% probability) but here we could
increase the probability for cases where we can track that argument is indeed
a local memory (or readonly which is also good)

	* ipa-fnsummary.c (dump_ipa_call_summary): Dump
	points_to_local_or_readonly_memory flag.
	(analyze_function_body): Compute points_to_local_or_readonly_memory
	flag.
	(remap_edge_change_prob): Rename to ...
	(remap_edge_params): ... this one; update
	points_to_local_or_readonly_memory.
	(remap_edge_summaries): Update.
	(read_ipa_call_summary): Stream the new flag.
	(write_ipa_call_summary): Likewise.
	* ipa-predicate.h (struct inline_param_summary): Add
	points_to_local_or_readonly_memory.
	(inline_param_summary::equal_to): Update.
	(inline_param_summary::useless_p): Update.

diff --git a/gcc/ipa-fnsummary.c b/gcc/ipa-fnsummary.c
index cbcf0c4c95c8cafaf0548e6575e33e7be2b39a6e..4c1c1f91482d0639f8fc8aed1bf22c8e8c76ebe4 100644 (file)
--- a/gcc/ipa-fnsummary.c
+++ b/gcc/ipa-fnsummary.c
@@ -980,6 +980,9 @@ dump_ipa_call_summary (FILE *f, int indent, struct cgraph_node *node,
            else if (prob != REG_BR_PROB_BASE)
              fprintf (f, "%*s op%i change %f%% of time\n", indent + 2, "", i,
                       prob * 100.0 / REG_BR_PROB_BASE);
+           if (es->param[i].points_to_local_or_readonly_memory)
+             fprintf (f, "%*s op%i points to local or readonly memory\n",
+                      indent + 2, "", i);
          }
       if (!edge->inline_failed)
        {
@@ -2671,6 +2674,9 @@ analyze_function_body (struct cgraph_node *node, bool early)
                      int prob = param_change_prob (&fbi, stmt, i);
                      gcc_assert (prob >= 0 && prob <= REG_BR_PROB_BASE);
                      es->param[i].change_prob = prob;
+                     es->param[i].points_to_local_or_readonly_memory
+                        = points_to_local_or_readonly_memory_p
+                            (gimple_call_arg (stmt, i));
                    }
                }
 
@@ -3781,15 +3787,17 @@ inline_update_callee_summaries (struct cgraph_node *node, int depth)
     ipa_call_summaries->get (e)->loop_depth += depth;
 }
 
-/* Update change_prob of EDGE after INLINED_EDGE has been inlined.
+/* Update change_prob and points_to_local_or_readonly_memory of EDGE after
+   INLINED_EDGE has been inlined.
+
    When function A is inlined in B and A calls C with parameter that
    changes with probability PROB1 and C is known to be passthrough
    of argument if B that change with probability PROB2, the probability
    of change is now PROB1*PROB2.  */
 
 static void
-remap_edge_change_prob (struct cgraph_edge *inlined_edge,
-                       struct cgraph_edge *edge)
+remap_edge_params (struct cgraph_edge *inlined_edge,
+                  struct cgraph_edge *edge)
 {
   if (ipa_node_params_sum)
     {
@@ -3823,7 +3831,16 @@ remap_edge_change_prob (struct cgraph_edge *inlined_edge,
                    prob = 1;
 
                  es->param[i].change_prob = prob;
+
+                 if (inlined_es
+                       ->param[id].points_to_local_or_readonly_memory)
+                   es->param[i].points_to_local_or_readonly_memory = true;
                }
+             if (!es->param[i].points_to_local_or_readonly_memory
+                 && jfunc->type == IPA_JF_CONST
+                 && points_to_local_or_readonly_memory_p
+                        (ipa_get_jf_constant (jfunc)))
+               es->param[i].points_to_local_or_readonly_memory = true;
            }
        }
     }
@@ -3856,7 +3873,7 @@ remap_edge_summaries (struct cgraph_edge *inlined_edge,
       if (e->inline_failed)
        {
           class ipa_call_summary *es = ipa_call_summaries->get (e);
-         remap_edge_change_prob (inlined_edge, e);
+         remap_edge_params (inlined_edge, e);
 
          if (es->predicate)
            {
@@ -3882,7 +3899,7 @@ remap_edge_summaries (struct cgraph_edge *inlined_edge,
       predicate p;
       next = e->next_callee;
 
-      remap_edge_change_prob (inlined_edge, e);
+      remap_edge_params (inlined_edge, e);
       if (es->predicate)
        {
          p = es->predicate->remap_after_inlining
@@ -4208,12 +4225,19 @@ read_ipa_call_summary (class lto_input_block *ib, struct cgraph_edge *e,
     {
       es->param.safe_grow_cleared (length, true);
       for (i = 0; i < length; i++)
-       es->param[i].change_prob = streamer_read_uhwi (ib);
+       {
+         es->param[i].change_prob = streamer_read_uhwi (ib);
+         es->param[i].points_to_local_or_readonly_memory
+           = streamer_read_uhwi (ib);
+       }
     }
   else
     {
       for (i = 0; i < length; i++)
-       streamer_read_uhwi (ib);
+       {
+         streamer_read_uhwi (ib);
+         streamer_read_uhwi (ib);
+       }
     }
 }
 
@@ -4438,7 +4462,10 @@ write_ipa_call_summary (struct output_block *ob, struct cgraph_edge *e)
     streamer_write_uhwi (ob, 0);
   streamer_write_uhwi (ob, es->param.length ());
   for (i = 0; i < (int) es->param.length (); i++)
-    streamer_write_uhwi (ob, es->param[i].change_prob);
+    {
+      streamer_write_uhwi (ob, es->param[i].change_prob);
+      streamer_write_uhwi (ob, es->param[i].points_to_local_or_readonly_memory);
+    }
 }
 
 

diff --git a/gcc/ipa-predicate.h b/gcc/ipa-predicate.h
index 9b75ffcf2809ad49cd7be7dc522ab43d2fd211b8..05e37073817cb2e02e066194a3ac668415b836bb 100644 (file)
--- a/gcc/ipa-predicate.h
+++ b/gcc/ipa-predicate.h
@@ -76,14 +76,18 @@ struct inline_param_summary
      parameters REG_BR_PROB_BASE.
 
      Value 0 is reserved for compile time invariants. */
-  int change_prob;
+  short change_prob;
+  unsigned points_to_local_or_readonly_memory : 1;
   bool equal_to (const inline_param_summary &other) const
   {
-    return change_prob == other.change_prob;
+    return change_prob == other.change_prob
+          && points_to_local_or_readonly_memory
+             == other.points_to_local_or_readonly_memory;
   }
   bool useless_p (void) const
   {
-    return change_prob == REG_BR_PROB_BASE;
+    return change_prob == REG_BR_PROB_BASE
+          && !points_to_local_or_readonly_memory;
   }
 };