alias.c (compare_base_decls): Simplify in-symtab check.

	gcc/
	* alias.c (compare_base_decls): Simplify in-symtab check.
	* cgraph.h (decl_in_symtab_p): Check DECL_IN_CONSTANT_POOL.

	testsuite/
	* gcc.dg/alias-15.c: New.

From-SVN: r231928

gcc/ChangeLog

+2015-12-23  Nathan Sidwell  <nathan@acm.org>
+
+	* alias.c (compare_base_decls): Simplify in-symtab check.
+	* cgraph.h (decl_in_symtab_p): Check DECL_IN_CONSTANT_POOL.
+
 2015-12-23  Dominik Vogt  <vogt@linux.vnet.ibm.com>
 
 	* config/s390/predicates.md ("larl_operand"): Remove now superfluous

gcc/alias.c

@@ -2038,13 +2038,12 @@ compare_base_decls (tree base1, tree base2)
   if (base1 == base2)
     return 1;
 
-  bool in_symtab1 = decl_in_symtab_p (base1);
-  bool in_symtab2 = decl_in_symtab_p (base2);
-
   /* Declarations of non-automatic variables may have aliases.  All other
      decls are unique.  */
-  if (in_symtab1 != in_symtab2 || !in_symtab1)
+  if (!decl_in_symtab_p (base1)
+      || !decl_in_symtab_p (base2))
     return 0;
+
   ret = symtab_node::get_create (base1)->equal_address_to
 		 (symtab_node::get_create (base2), true);
   if (ret == 2)

gcc/cgraph.h

@@ -2294,13 +2294,19 @@ symtab_node::real_symbol_p (void)
 }
 
 /* Return true if DECL should have entry in symbol table if used.
-   Those are functions and static & external veriables*/
+   Those are functions and static & external non-constpool variables.
+   We do not expect constant pool variables in the varpool, as they're
+   not related to other variables, and simply lazily inserting them
+   using the regular interface results in varpool thinking they are
+   externally provided -- which results in erroneous assembly emission
+   as an undefined decl.  */
 
 static inline bool
 decl_in_symtab_p (const_tree decl)
 {
   return (TREE_CODE (decl) == FUNCTION_DECL
           || (TREE_CODE (decl) == VAR_DECL
+	      && !DECL_IN_CONSTANT_POOL (decl)
 	      && (TREE_STATIC (decl) || DECL_EXTERNAL (decl))));
 }
 

gcc/testsuite/ChangeLog

+2015-12-23  Nathan Sidwell  <nathan@acm.org>
+
+	* gcc.dg/alias-15.c: New. 
+
 2015-12-23  Thomas Schwinge  <thomas@codesourcery.com>
 
 	* g++.dg/dg.exp (tests): Prune "goacc/*" and "goacc-gomp/*" files.

gcc/testsuite/gcc.dg/alias-15.c

+/* { dg-do compile } */
+/* { dg-additional-options  "-O2 -fdump-ipa-cgraph" } */
+
+/* RTL-level CSE shouldn't introduce LCO (for the string) into varpool */
+char *p;
+
+void foo ()
+{
+  p = "abc\n";
+
+  while (*p != '\n')
+    p++;
+}
+
+/* { dg-final { scan-ipa-dump-not "LC0" "cgraph" } } */