PR debug/50317

	* tree-ssa-dce.c (remove_dead_stmt): Add a debug stmt when removing
	as unnecessary a store to a variable with gimple reg type.
	* tree-ssa-live.c (remove_unused_locals): Clear TREE_ADDRESSABLE bit
	on local unreferenced variables.
	* cfgexpand.c (expand_gimple_basic_block): Don't emit DEBUG_INSNs
	for !target_for_debug_bind variables.

4 files changed, 46 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1261e4befc6..0ab88fa1198 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2011-12-01  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/50317
+	* tree-ssa-dce.c (remove_dead_stmt): Add a debug stmt when removing
+	as unnecessary a store to a variable with gimple reg type.
+	* tree-ssa-live.c (remove_unused_locals): Clear TREE_ADDRESSABLE bit
+	on local unreferenced variables.
+	* cfgexpand.c (expand_gimple_basic_block): Don't emit DEBUG_INSNs
+	for !target_for_debug_bind variables.
+
 2011-12-01  Patrick Marlier  <patrick.marlier@gmail.com>
 
 	PR middle-end/51273
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 2a82b032f5d..e5a7a392eb4 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -3903,6 +3903,11 @@ expand_gimple_basic_block (basic_block bb)
 	      rtx val;
 	      enum machine_mode mode;
 
+	      if (TREE_CODE (var) != DEBUG_EXPR_DECL
+		  && TREE_CODE (var) != LABEL_DECL
+		  && !target_for_debug_bind (var))
+		goto delink_debug_stmt;
+
 	      if (gimple_debug_bind_has_value_p (stmt))
 		value = gimple_debug_bind_get_value (stmt);
 	      else
@@ -3932,6 +3937,7 @@ expand_gimple_basic_block (basic_block bb)
 		  PAT_VAR_LOCATION_LOC (val) = (rtx)value;
 		}
 
+	    delink_debug_stmt:
 	      /* In order not to generate too many debug temporaries,
 	         we delink all uses of debug statements we already expanded.
 		 Therefore debug statements between definition and real
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index d6fbe622df0..a710de620df 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -1215,6 +1215,26 @@ remove_dead_stmt (gimple_stmt_iterator *i, basic_block bb)
 	  ei_next (&ei);
     }
 
+  /* If this is a store into a variable that is being optimized away,
+     add a debug bind stmt if possible.  */
+  if (MAY_HAVE_DEBUG_STMTS
+      && gimple_assign_single_p (stmt)
+      && is_gimple_val (gimple_assign_rhs1 (stmt)))
+    {
+      tree lhs = gimple_assign_lhs (stmt);
+      if ((TREE_CODE (lhs) == VAR_DECL || TREE_CODE (lhs) == PARM_DECL)
+	  && !DECL_IGNORED_P (lhs)
+	  && is_gimple_reg_type (TREE_TYPE (lhs))
+	  && !is_global_var (lhs)
+	  && !DECL_HAS_VALUE_EXPR_P (lhs))
+	{
+	  tree rhs = gimple_assign_rhs1 (stmt);
+	  gimple note
+	    = gimple_build_debug_bind (lhs, unshare_expr (rhs), stmt);
+	  gsi_insert_after (i, note, GSI_SAME_STMT);
+	}
+    }
+
   unlink_stmt_vdef (stmt);
   gsi_remove (i, true);
   release_defs (stmt);
diff --git a/gcc/tree-ssa-live.c b/gcc/tree-ssa-live.c
index b8a056ebdac..103e4f7155a 100644
--- a/gcc/tree-ssa-live.c
+++ b/gcc/tree-ssa-live.c
@@ -1,5 +1,5 @@
 /* Liveness for SSA trees.
-   Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009, 2010
+   Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011
    Free Software Foundation, Inc.
    Contributed by Andrew MacLeod <amacleod@redhat.com>
 
@@ -814,7 +814,15 @@ remove_unused_locals (void)
 	      bitmap_set_bit (global_unused_vars, DECL_UID (var));
 	    }
 	  else
-	    continue;
+	    {
+	      /* For unreferenced local vars drop TREE_ADDRESSABLE
+		 bit in case it is referenced from debug stmts.  */
+	      if (DECL_CONTEXT (var) == current_function_decl
+		  && TREE_ADDRESSABLE (var)
+		  && is_gimple_reg_type (TREE_TYPE (var)))
+		TREE_ADDRESSABLE (var) = 0;
+	      continue;
+	    }
 	}
       else if (TREE_CODE (var) == VAR_DECL
 	       && DECL_HARD_REGISTER (var)