re PR debug/54693 (VTA guality issues with loops)

gcc/ChangeLog:
PR debug/54693
* tree-ssa-threadedge.c (thread_around_empty_block): Copy
debug temps from predecessor before threading.
gcc/testsuite/ChangeLog:
PR debug/54693
* gcc.dg/guality/pr54693.c: New.

From-SVN: r192961

gcc/ChangeLog

 2012-10-29  Alexandre Oliva <aoliva@redhat.com>
 
+	PR debug/54693
+	* tree-ssa-threadedge.c (thread_around_empty_block): Copy
+	debug temps from predecessor before threading.
+
+2012-10-29  Alexandre Oliva <aoliva@redhat.com>
+
 	PR debug/54551
 	PR debug/54693
 	* valtrack.c (dead_debug_global_find): Accept NULL dtemp.

gcc/testsuite/ChangeLog

+2012-10-29  Alexandre Oliva <aoliva@redhat.com>
+
+	PR debug/54693
+	* gcc.dg/guality/pr54693.c: New.
+
 2012-10-29  Marc Glisse  <marc.glisse@inria.fr>
 
 	PR middle-end/55027

gcc/testsuite/gcc.dg/guality/pr54693.c

+/* PR debug/54693 */
+/* { dg-do run } */
+/* { dg-options "-g" } */
+
+__attribute__((noinline, noclone)) void
+foo (char *str, char c)
+{
+  asm volatile ("" : : "r" (str), "r" (c) : "memory");
+  *str = c;
+}
+
+int
+main ()
+{
+  int i;
+  char c;
+  char arr[11];
+
+  for (i = 0; i < 10; i++)
+    {
+      c = 0x30 + i;
+      foo (&arr[i], c); /* { dg-final { gdb-test 22 "i" "c - 48" } } */
+    }
+
+  __builtin_printf ("arr = %s\n", arr);
+  return 0;
+}
+

gcc/tree-ssa-threadedge.c

@@ -637,6 +637,24 @@ thread_around_empty_block (edge taken_edge,
   if (!single_pred_p (bb))
     return NULL;
 
+  /* Before threading, copy DEBUG stmts from the predecessor, so that
+     we don't lose the bindings as we redirect the edges.  */
+  if (MAY_HAVE_DEBUG_STMTS)
+    {
+      gsi = gsi_after_labels (bb);
+      for (gimple_stmt_iterator si = gsi_last_bb (taken_edge->src);
+	   !gsi_end_p (si); gsi_prev (&si))
+	{
+	  stmt = gsi_stmt (si);
+	  if (!is_gimple_debug (stmt))
+	    continue;
+
+	  stmt = gimple_copy (stmt);
+	  /* ??? Should we drop the location of the copy?  */
+	  gsi_insert_before (&gsi, stmt, GSI_NEW_STMT);
+	}
+    }
+
   /* This block must have more than one successor.  */
   if (single_succ_p (bb))
     return NULL;