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Speedup inliner on Chromium

Message ID 20150309041632.GE50226@kam.mff.cuni.cz
State New
Headers show

Commit Message

Jan Hubicka March 9, 2015, 4:16 a.m. UTC
Hi,
compiling Chromium, ipa-icf introduces thousdands of aliases of one function
from iostream traits (because it is duplicated so many times due to ipa-sra
privatizing it to every compile unit).

This triggers non-linear behaviour in
will_be_removed_from_program_if_no_direct_calls_p.  This patch makes inliner to
not call it that often. I also noticed that the function is not quite corect
about inlining and fixed it.

Bootstrapped/regtested x86_64-linux, will commit it later today.

Honza
	* ipa-inline-analysis.c (check_callers): Check
	node->can_remove_if_no_direct_calls_and_refs_p.
	(growth_likely_positive): Reorganize to call
	can_remove_if_no_direct_calls_p later.
	* cgraph.h (will_be_removed_from_program_if_no_direct_calls_p,
	will_be_removed_from_program_if_no_direct_calls_p): Add 
	will_inline parameter.
	* cgraph.c (cgraph_node::can_remove_if_no_direct_calls_p,
	cgraph_node::will_be_removed_from_program_if_no_direct_calls_p):
	Handle inliner case correctly.
diff mbox

Patch

Index: ipa-inline-analysis.c
===================================================================
--- ipa-inline-analysis.c	(revision 221267)
+++ ipa-inline-analysis.c	(working copy)
@@ -3978,6 +3978,9 @@  check_callers (cgraph_node *node, int *m
 {
   ipa_ref *ref;
 
+  if (!node->can_remove_if_no_direct_calls_and_refs_p ())
+    return true;
+
   for (cgraph_edge *e = node->callers; e; e = e->next_caller)
     {
       (*max_callers)--;
@@ -4007,23 +4010,13 @@  growth_likely_positive (struct cgraph_no
   struct cgraph_edge *e;
   gcc_checking_assert (edge_growth > 0);
 
+  /* First quickly check if NODE is removable at all.  */
   if (DECL_EXTERNAL (node->decl))
     return true;
-  /* Unlike for functions called once, we play unsafe with
-     COMDATs.  We can allow that since we know functions
-     in consideration are small (and thus risk is small) and
-     moreover grow estimates already accounts that COMDAT
-     functions may or may not disappear when eliminated from
-     current unit. With good probability making aggressive
-     choice in all units is going to make overall program
-     smaller.  */
-  if (DECL_COMDAT (node->decl))
-    {
-      if (!node->can_remove_if_no_direct_calls_p ())
-	return true;
-    }
-  else if (!node->will_be_removed_from_program_if_no_direct_calls_p ())
+  if (!node->can_remove_if_no_direct_calls_and_refs_p ()
+      || node->address_taken)
     return true;
+
   max_callers = inline_summaries->get (node)->size * 4 / edge_growth + 2;
 
   for (e = node->callers; e; e = e->next_caller)
@@ -4039,6 +4032,22 @@  growth_likely_positive (struct cgraph_no
     if (check_callers (dyn_cast <cgraph_node *> (ref->referring), &max_callers))
       return true;
 
+  /* Unlike for functions called once, we play unsafe with
+     COMDATs.  We can allow that since we know functions
+     in consideration are small (and thus risk is small) and
+     moreover grow estimates already accounts that COMDAT
+     functions may or may not disappear when eliminated from
+     current unit. With good probability making aggressive
+     choice in all units is going to make overall program
+     smaller.  */
+  if (DECL_COMDAT (node->decl))
+    {
+      if (!node->can_remove_if_no_direct_calls_p ())
+	return true;
+    }
+  else if (!node->will_be_removed_from_program_if_no_direct_calls_p ())
+    return true;
+
   return estimate_growth (node) > 0;
 }
 
Index: cgraph.h
===================================================================
--- cgraph.h	(revision 221268)
+++ cgraph.h	(working copy)
@@ -1110,16 +1110,23 @@  public:
      all uses of COMDAT function does not make it necessarily disappear from
      the program unless we are compiling whole program or we do LTO.  In this
      case we know we win since dynamic linking will not really discard the
-     linkonce section.  */
-  bool will_be_removed_from_program_if_no_direct_calls_p (void);
+     linkonce section.  
+
+     If WILL_INLINE is true, assume that function will be inlined into all the
+     direct calls.  */
+  bool will_be_removed_from_program_if_no_direct_calls_p
+	 (bool will_inline = false);
 
   /* Return true when function can be removed from callgraph
-     if all direct calls are eliminated.  */
+     if all direct calls and references are eliminated.  The function does
+     not take into account comdat groups.  */
   bool can_remove_if_no_direct_calls_and_refs_p (void);
 
   /* Return true when function cgraph_node and its aliases can be removed from
-     callgraph if all direct calls are eliminated.  */
-  bool can_remove_if_no_direct_calls_p (void);
+     callgraph if all direct calls are eliminated. 
+     If WILL_INLINE is true, assume that function will be inlined into all the
+     direct calls.  */
+  bool can_remove_if_no_direct_calls_p (bool will_inline = false);
 
   /* Return true when callgraph node is a function with Gimple body defined
      in current unit.  Functions can also be define externally or they
Index: cgraph.c
===================================================================
--- cgraph.c	(revision 221267)
+++ cgraph.c	(working copy)
@@ -2415,7 +2415,7 @@  nonremovable_p (cgraph_node *node, void
    calls to THIS.  */
 
 bool
-cgraph_node::can_remove_if_no_direct_calls_p (void)
+cgraph_node::can_remove_if_no_direct_calls_p (bool will_inline)
 {
   struct ipa_ref *ref;
 
@@ -2430,6 +2430,9 @@  cgraph_node::can_remove_if_no_direct_cal
       return !call_for_symbol_and_aliases (nonremovable_p, NULL, true);
     }
 
+  if (will_inline && address_taken)
+    return false;
+
   /* Otheriwse check if we can remove the symbol itself and then verify
      that only uses of the comdat groups are direct call to THIS
      or its aliases.   */
@@ -2454,12 +2457,16 @@  cgraph_node::can_remove_if_no_direct_cal
       /* If we see different symbol than THIS, be sure to check calls.  */
       if (next->ultimate_alias_target () != target)
 	for (cgraph_edge *e = next->callers; e; e = e->next_caller)
-	  if (e->caller->get_comdat_group () != get_comdat_group ())
+	  if (e->caller->get_comdat_group () != get_comdat_group ()
+	      || will_inline)
 	    return false;
 
-      for (int i = 0; next->iterate_referring (i, ref); i++)
-	if (ref->referring->get_comdat_group () != get_comdat_group ())
-	  return false;
+      /* If function is not being inlined, we care only about
+	 references outside of the comdat group.  */
+      if (!will_inline)
+        for (int i = 0; next->iterate_referring (i, ref); i++)
+	  if (ref->referring->get_comdat_group () != get_comdat_group ())
+	    return false;
     }
   return true;
 }
@@ -2479,9 +2486,9 @@  cgraph_node::can_remove_if_no_direct_cal
    linkonce section.  */
 
 bool
-cgraph_node::will_be_removed_from_program_if_no_direct_calls_p (void)
+cgraph_node::will_be_removed_from_program_if_no_direct_calls_p
+	 (bool will_inline)
 {
-  struct ipa_ref *ref;
   gcc_assert (!global.inlined_to);
   if (DECL_EXTERNAL (decl))
     return true;
@@ -2496,6 +2503,9 @@  cgraph_node::will_be_removed_from_progra
       if (same_comdat_group && externally_visible)
 	{
 	  struct cgraph_node *target = ultimate_alias_target ();
+
+	  if (will_inline && address_taken)
+	    return true;
 	  for (cgraph_node *next = dyn_cast<cgraph_node *> (same_comdat_group);
 	       next != this;
 	       next = dyn_cast<cgraph_node *> (next->same_comdat_group))
@@ -2510,18 +2520,15 @@  cgraph_node::will_be_removed_from_progra
 		 be sure to check calls.  */
 	      if (next->ultimate_alias_target () != target)
 		for (cgraph_edge *e = next->callers; e; e = e->next_caller)
-		  if (e->caller->get_comdat_group () != get_comdat_group ())
+		  if (e->caller->get_comdat_group () != get_comdat_group ()
+		      || will_inline)
 		    return false;
-
-	      for (int i = 0; next->iterate_referring (i, ref); i++)
-		if (ref->referring->get_comdat_group () != get_comdat_group ())
-		  return false;
 	    }
 	}
       return true;
     }
   else
-    return can_remove_if_no_direct_calls_p ();
+    return can_remove_if_no_direct_calls_p (will_inline);
 }