Re: [PATCH] ICF: move readonly decision for variables to the right place

[Jan Hubicka <hubicka@ucw.cz>]

Hi,
this is a variant of patch I commited.
It takes care to load the constructor to memory in sem_variable::equals
and donot touch it earlier.  I also made sem_variable::parse to skip volatile
and reigster variables.

Bootstrapped/regtested x86_64-linux, lto-bootstrapped with -fmerge-all-constants
comitted.

Honza

2015-02-28  Martin Liska  <mliska@suse.cz>
	    Jan Hubicka   <hubicka@ucw.cz>

	* ipa-icf.c (sem_variable::equals): Improve debug output;
	get variable constructor.
	(sem_variable::parse): Do not filter out too early; give up on
	volatile and register vars.
	(sem_item_optimizer::filter_removed_items): Filter out nonreadonly
	variables.
	* ipa-icf.h (sem_variable::init): Do not set ctor.
	(sem_variable::ctor): Remove.

gcc/testsuite/ChangeLog:

2015-02-28  Martin Liska  <mliska@suse.cz>
	    Jan Hubicka   <hubicka@ucw.cz>

	* gcc.dg/ipa/ipa-icf-35.c: New test.
	* gcc.dg/ipa/ipa-icf-36.c: New test.
	* gcc.dg/ipa/ipa-icf-37.c: New test.
Index: ipa-icf.c
===================================================================
--- ipa-icf.c	(revision 221096)
+++ ipa-icf.c	(working copy)
@@ -1448,18 +1452,29 @@ sem_variable::equals_wpa (sem_item *item
 
 /* Returns true if the item equals to ITEM given as argument.  */
 
+/* Returns true if the item equals to ITEM given as argument.  */
+
 bool
 sem_variable::equals (sem_item *item,
-		      hash_map <symtab_node *, sem_item *> & ARG_UNUSED (ignored_nodes))
+		      hash_map <symtab_node *, sem_item *> &)
 {
   gcc_assert (item->type == VAR);
+  bool ret;
 
-  sem_variable *v = static_cast<sem_variable *>(item);
-
-  if (!ctor || !v->ctor)
-    return return_false_with_msg ("ctor is missing for semantic variable");
+  if (DECL_INITIAL (decl) == error_mark_node && in_lto_p)
+    dyn_cast <varpool_node *>(node)->get_constructor ();
+  if (DECL_INITIAL (item->decl) == error_mark_node && in_lto_p)
+    dyn_cast <varpool_node *>(item->node)->get_constructor ();
+
+  ret = sem_variable::equals (DECL_INITIAL (decl),
+			      DECL_INITIAL (item->node->decl));
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    fprintf (dump_file,
+	     "Equals called for vars:%s:%s (%u:%u) (%s:%s) with result: %s\n\n",
+	     name(), item->name (), node->order, item->node->order, asm_name (),
+	     item->asm_name (), ret ? "true" : "false");
 
-  return sem_variable::equals (ctor, v->ctor);
+  return ret;
 }
 
 /* Compares trees T1 and T2 for semantic equality.  */
@@ -1653,24 +1668,7 @@ sem_variable::equals (tree t1, tree t2)
 sem_variable *
 sem_variable::parse (varpool_node *node, bitmap_obstack *stack)
 {
-  tree decl = node->decl;
-
-  if (node->alias)
-    return NULL;
-
-  bool readonly = TYPE_P (decl) ? TYPE_READONLY (decl) : TREE_READONLY (decl);
-  if (!readonly)
-    return NULL;
-
-  bool can_handle = DECL_VIRTUAL_P (decl)
-		    || flag_merge_constants >= 2
-		    || (!TREE_ADDRESSABLE (decl) && !node->externally_visible);
-
-  if (!can_handle || DECL_EXTERNAL (decl))
-    return NULL;
-
-  tree ctor = ctor_for_folding (decl);
-  if (!ctor)
+  if (TREE_THIS_VOLATILE (node->decl) || DECL_HARD_REGISTER (node->decl))
     return NULL;
 
   sem_variable *v = new sem_variable (node, 0, stack);
@@ -1686,8 +1684,8 @@ hashval_t
 sem_variable::get_hash (void)
 {
   if (hash)
-    return hash;
 
+    return hash;
   /* All WPA streamed in symbols should have their hashes computed at compile
      time.  At this point, the constructor may not be in memory at all.
      DECL_INITIAL (decl) would be error_mark_node in that case.  */
@@ -2155,7 +2153,14 @@ sem_item_optimizer::filter_removed_items
 	  if (!flag_ipa_icf_variables)
 	    remove_item (item);
 	  else
-	    filtered.safe_push (item);
+	    {
+	      /* Filter out non-readonly variables.  */
+	      tree decl = item->decl;
+	      if (TREE_READONLY (decl))
+		filtered.safe_push (item);
+	      else
+		remove_item (item);
+	    }
         }
     }
 
Index: ipa-icf.h
===================================================================
--- ipa-icf.h	(revision 221096)
+++ ipa-icf.h	(working copy)
@@ -393,7 +393,6 @@ public:
   inline virtual void init (void)
   {
     decl = get_node ()->decl;
-    ctor = ctor_for_folding (decl);
   }
 
   virtual hashval_t get_hash (void);
@@ -415,9 +414,6 @@ public:
   /* Parser function that visits a varpool NODE.  */
   static sem_variable *parse (varpool_node *node, bitmap_obstack *stack);
 
-  /* Variable constructor.  */
-  tree ctor;
-
 private:
   /* Iterates though a constructor and identifies tree references
      we are interested in semantic function equality.  */
Index: testsuite/gcc.dg/ipa/ipa-icf-35.c
===================================================================
--- testsuite/gcc.dg/ipa/ipa-icf-35.c	(revision 0)
+++ testsuite/gcc.dg/ipa/ipa-icf-35.c	(revision 0)
@@ -0,0 +1,31 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-icf"  } */
+
+void f1()
+{
+}
+
+void f2()
+{
+}
+
+static void (*a)(void)=&f1;
+static void (*b)(void)=&f1;
+static void (*c)(void)=&f2;
+static void (*d)(void)=&f2;
+
+int main()
+{
+  a();
+  b();
+  c();
+  d();
+
+  return 0;
+}
+
+/* { dg-final { scan-ipa-dump "Equal symbols: 3" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:f2->f1" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:d->c" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:b->a" "icf"  } } */
+/* { dg-final { cleanup-ipa-dump "icf" } } */
Index: testsuite/gcc.dg/ipa/ipa-icf-36.c
===================================================================
--- testsuite/gcc.dg/ipa/ipa-icf-36.c	(revision 0)
+++ testsuite/gcc.dg/ipa/ipa-icf-36.c	(revision 0)
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-icf -fmerge-all-constants"  } */
+static int a;
+static int b;
+static const int c = 2;
+static const int d = 2;
+static char * e = "test";
+static char * f = "test";
+static int g[3]={1,2,3};
+static int h[3]={1,2,3};
+static const int *i=&c;
+static const int *j=&c;
+static const int *k=&d;
+int t(int tt)
+{
+  switch (tt)
+  {
+    case 1: return a;
+    case 2: return b;
+    case 3: return c;
+    case 4: return d;
+    case 5: return e[1];
+    case 6: return f[1];
+    case 7: return g[1];
+    case 8: return h[1];
+    case 9: return i[0];
+    case 10: return j[0];
+    case 11: return k[0];
+  }
+}
+/* { dg-final { scan-ipa-dump "Equal symbols: 6" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:b->a" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:d->c" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:f->e" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:h->g" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:k->i" "icf"  } } */
Index: testsuite/gcc.dg/ipa/ipa-icf-37.c
===================================================================
--- testsuite/gcc.dg/ipa/ipa-icf-37.c	(revision 0)
+++ testsuite/gcc.dg/ipa/ipa-icf-37.c	(revision 0)
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-icf"  } */
+static int a;
+static int b;
+static const int c = 2;
+static const int d = 2;
+static char * e = "test";
+static char * f = "test";
+static int g[3]={1,2,3};
+static int h[3]={1,2,3};
+static const int *i=&c;
+static const int *j=&c;
+static const int *k=&d;
+int t(int tt)
+{
+  switch (tt)
+  {
+    case 1: return a;
+    case 2: return b;
+    case 3: return c;
+    case 4: return d;
+    case 5: return e[1];
+    case 6: return f[1];
+    case 7: return g[1];
+    case 8: return h[1];
+    case 9: return i[0];
+    case 10: return j[0];
+    case 11: return k[0];
+  }
+}
+/* { dg-final { scan-ipa-dump "Equal symbols: 5" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:b->a" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:d->c" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:f->e" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:h->g" "icf"  } } */
+/* { dg-final { scan-ipa-dump "Semantic equality hit:j->i" "icf"  } } */