re PR ipa/81360 (ice in estimate_edge_growth, at ipa-inline.h:86)

	PR ipa/81360
	* cgraph.h (symtab_node::output_to_lto_symbol_table_p): Declare
	* symtab.c: Include builtins.h
	(symtab_node::output_to_lto_symbol_table_p): Move here
	from lto-streamer-out.c:output_symbol_p.
	* lto-streamer-out.c (write_symbol): Turn early exit to assert.
	(output_symbol_p): Move all logic to symtab.c
	(produce_symtab): Update.

	* lto.c (unify_scc): Register prevailing trees, not trees to be freed.
	(read_cgraph_and_symbols): Use
	symtab_node::output_to_lto_symbol_table_p.

From-SVN: r257490

1 files changed, 56 insertions, 0 deletions

diff --git a/gcc/symtab.c b/gcc/symtab.c
index ff827cb..b54183f 100644
--- a/gcc/symtab.c
+++ b/gcc/symtab.c
@@ -37,6 +37,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "calls.h"
 #include "stringpool.h"
 #include "attribs.h"
+#include "builtins.h"
 
 static const char *ipa_ref_use_name[] = {"read","write","addr","alias","chkp"};
 
@@ -2292,3 +2293,58 @@ symtab_node::binds_to_current_def_p (symtab_node *ref)
 
   return false;
 }
+
+/* Return true if symbol should be output to the symbol table.  */
+
+bool
+symtab_node::output_to_lto_symbol_table_p (void)
+{
+  /* Only externally visible symbols matter.  */
+  if (!TREE_PUBLIC (decl))
+    return false;
+  if (!real_symbol_p ())
+    return false;
+  /* FIXME: variables probably should not be considered as real symbols at
+     first place.  */
+  if (VAR_P (decl) && DECL_HARD_REGISTER (decl))
+    return false;
+  /* FIXME: Builtins corresponding to real functions probably should have
+     symbol table entries.  */
+  if (is_builtin_fn (decl))
+    return false;
+
+  /* We have real symbol that should be in symbol table.  However try to trim
+     down the refernces to libraries bit more because linker will otherwise
+     bring unnecesary object files into the final link.
+     FIXME: The following checks can easily be confused i.e. by self recursive
+     function or self-referring variable.  */
+
+  /* We keep external functions in symtab for sake of inlining
+     and devirtualization.  We do not want to see them in symbol table as
+     references unless they are really used.  */
+  cgraph_node *cnode = dyn_cast <cgraph_node *> (this);
+  if (cnode && (!definition || DECL_EXTERNAL (decl))
+      && cnode->callers)
+    return true;
+
+ /* Ignore all references from external vars initializers - they are not really
+    part of the compilation unit until they are used by folding.  Some symbols,
+    like references to external construction vtables can not be referred to at
+    all.  We decide this at can_refer_decl_in_current_unit_p.  */
+ if (!definition || DECL_EXTERNAL (decl))
+    {
+      int i;
+      struct ipa_ref *ref;
+      for (i = 0; iterate_referring (i, ref); i++)
+	{
+	  if (ref->use == IPA_REF_ALIAS)
+	    continue;
+          if (is_a <cgraph_node *> (ref->referring))
+	    return true;
+	  if (!DECL_EXTERNAL (ref->referring->decl))
+	    return true;
+	}
+      return false;
+    }
+  return true;
+}