From 2591ae50594b4e85565c1858bdf73056246485b9 Mon Sep 17 00:00:00 2001
From: nathan <nathan@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Wed, 23 Dec 2015 14:47:39 +0000
Subject: [PATCH] 	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.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@231928 138bc75d-0d04-0410-961f-82ee72b054a4
---
 gcc/ChangeLog                   |  5 +++++
 gcc/alias.c                     |  7 +++----
 gcc/cgraph.h                    |  8 +++++++-
 gcc/testsuite/ChangeLog         |  4 ++++
 gcc/testsuite/gcc.dg/alias-15.c | 15 +++++++++++++++
 5 files changed, 34 insertions(+), 5 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/alias-15.c

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d01894a58dd..e789c11c8ec 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+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
diff --git a/gcc/alias.c b/gcc/alias.c
index 1ab96008743..42a974a5970 100644
--- a/gcc/alias.c
+++ b/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)
diff --git a/gcc/cgraph.h b/gcc/cgraph.h
index ba14215ed6f..fe7c1940c4e 100644
--- a/gcc/cgraph.h
+++ b/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))));
 }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1924c24002e..79a1827e665 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+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.
diff --git a/gcc/testsuite/gcc.dg/alias-15.c b/gcc/testsuite/gcc.dg/alias-15.c
new file mode 100644
index 00000000000..0a8e69b61ec
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/alias-15.c
@@ -0,0 +1,15 @@
+/* { 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" } } */
-- 
2.11.4.GIT