Fix indirect call profiling for COMDAT symbols

[Jan Hubicka <hubicka at ucw dot cz>]

Hi,
while looking into firefox profiles, I noticed that we miss devirtualizations
to comdat symbols, because we manage to get different profile_id in each
unit.  This is easily fixed by the following patch that makes profiled_id
to by crc32 of the symbol name in this case.

Bootstrapped/regtested x86_64-linux, tested with firefox, will
commit it tomorrow.

	* coverage.c (coverage_compute_profile_id): Make stable for
	global symbols
	* ipa-utils.c (ipa_merge_profiles): Merge profile_id.
	* lto/lto-symtab.c (lto_cgraph_replace_node): Don't re-merge
	tp_first_run.
Index: coverage.c
===================================================================
--- coverage.c	(revision 209170)
+++ coverage.c	(working copy)
@@ -555,18 +555,31 @@ coverage_compute_lineno_checksum (void)
 unsigned
 coverage_compute_profile_id (struct cgraph_node *n)
 {
-  expanded_location xloc
-    = expand_location (DECL_SOURCE_LOCATION (n->decl));
-  unsigned chksum = xloc.line;
+  unsigned chksum;
 
-  chksum = coverage_checksum_string (chksum, xloc.file);
-  chksum = coverage_checksum_string
-    (chksum, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (n->decl)));
-  if (first_global_object_name)
-    chksum = coverage_checksum_string
-      (chksum, first_global_object_name);
-  chksum = coverage_checksum_string
-    (chksum, aux_base_name);
+  /* Externally visible symbols have unique name.  */
+  if (TREE_PUBLIC (n->decl) || DECL_EXTERNAL (n->decl))
+    {
+      /* Do not use coverage_checksum_string here; we really want unique
+	 symbol name id.  */
+      chksum = crc32_string
+	(0, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (n->decl)));
+    }
+  else
+    {
+      expanded_location xloc
+	= expand_location (DECL_SOURCE_LOCATION (n->decl));
+
+      chksum = xloc.line;
+      chksum = coverage_checksum_string (chksum, xloc.file);
+      chksum = coverage_checksum_string
+	(chksum, IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (n->decl)));
+      if (first_global_object_name)
+	chksum = coverage_checksum_string
+	  (chksum, first_global_object_name);
+      chksum = coverage_checksum_string
+	(chksum, aux_base_name);
+    }
 
   /* Non-negative integers are hopefully small enough to fit in all targets.  */
   return chksum & 0x7fffffff;
Index: ipa-utils.c
===================================================================
--- ipa-utils.c	(revision 209170)
+++ ipa-utils.c	(working copy)
@@ -660,6 +660,21 @@ ipa_merge_profiles (struct cgraph_node *
   if (dst->tp_first_run > src->tp_first_run && src->tp_first_run)
     dst->tp_first_run = src->tp_first_run;
 
+  if (src->profile_id)
+    {
+      if (!dst->profile_id)
+	dst->profile_id = src->profile_id;
+      else
+	{
+	 if (src->profile_id != dst->profile_id)
+	   {
+	     dump_cgraph_node (stderr, src);
+	     dump_cgraph_node (stderr, dst);
+	   }
+	 gcc_assert (src->profile_id == dst->profile_id);
+	}
+    }
+
   if (!dst->count)
     return;
   if (cgraph_dump_file)
Index: lto/lto-symtab.c
===================================================================
--- lto/lto-symtab.c	(revision 209170)
+++ lto/lto-symtab.c	(working copy)
@@ -91,12 +91,6 @@ lto_cgraph_replace_node (struct cgraph_n
   if (node->decl != prevailing_node->decl)
     cgraph_release_function_body (node);
 
-  /* Time profile merging */
-  if (node->tp_first_run)
-    prevailing_node->tp_first_run = prevailing_node->tp_first_run ?
-      MIN (prevailing_node->tp_first_run, node->tp_first_run) :
-      node->tp_first_run;
-
   /* Finally remove the replaced node.  */
   cgraph_remove_node (node);
 }