cgraph: Avoid creating multiple *.localalias aliases with the same name [PR93384]

The following testcase FAILs on powerpc64le-linux with assembler errors, as we
emit a call to bar.localalias, then .set bar.localalias, bar twice and then
another call to bar.localalias.  The problem is that bar.localalias can be created
at various stages and e.g. ipa-pure-const can slightly adjust the original decl,
so that the existing bar.localalias isn't considered usable (different
flags_from_decl_or_type).  In that case, we'd create another bar.localalias, which
clashes with the existing name.

Fixed by retrying with another name if it is already present.  The various localalias
aliases shouldn't be that many, from different partitions they would be lto_priv
suffixed and in most cases they would already have the same type/flags/attributes.

2020-01-30  Jakub Jelinek  <jakub@redhat.com>

	PR lto/93384
	* symtab.c (symtab_node::noninterposable_alias): If localalias
	already exists, but is not usable, append numbers after it until
	a unique name is found.  Formatting fix.

	* gcc.dg/lto/pr93384_0.c: New test.
	* gcc.dg/lto/pr93384_1.c: New file.

1 files changed, 12 insertions, 2 deletions

diff --git a/gcc/symtab.c b/gcc/symtab.c
index f141200..eae891a 100644
--- a/gcc/symtab.c
+++ b/gcc/symtab.c
@@ -1864,7 +1864,7 @@ symtab_node::noninterposable_alias (void)
   symtab_node *node = ultimate_alias_target ();
   gcc_assert (!node->alias && !node->weakref);
   node->call_for_symbol_and_aliases (symtab_node::noninterposable_alias,
-				   (void *)&new_node, true);
+				     (void *)&new_node, true);
   if (new_node)
     return new_node;
 
@@ -1875,7 +1875,17 @@ symtab_node::noninterposable_alias (void)
   /* Otherwise create a new one.  */
   new_decl = copy_node (node->decl);
   DECL_DLLIMPORT_P (new_decl) = 0;
-  DECL_NAME (new_decl) = clone_function_name (node->decl, "localalias");
+  tree name = clone_function_name (node->decl, "localalias");
+  if (!flag_wpa)
+    {
+      unsigned long num = 0;
+      /* In the rare case we already have a localalias, but the above
+	 node->call_for_symbol_and_aliases call didn't find any suitable,
+	 iterate until we find one not used yet.  */
+      while (symtab_node::get_for_asmname (name))
+	name = clone_function_name (node->decl, "localalias", num++);
+    }
+  DECL_NAME (new_decl) = name;
   if (TREE_CODE (new_decl) == FUNCTION_DECL)
     DECL_STRUCT_FUNCTION (new_decl) = NULL;
   DECL_INITIAL (new_decl) = NULL;