[PATCH] dwarf2out: Use normal constant values in bound_info if possible.

[Mark Wielaard]

	* dwarf2out.c (add_bound_info): If HOST_WIDE_INT is big enough,
	then represent the bound as normal constant value.
---
 gcc/ChangeLog   |    5 +++++
 gcc/dwarf2out.c |   32 ++++++++++++++++++++------------
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3ab789a..8a31187 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2014-03-20  Mark Wielaard  <mjw@redhat.com>
+
+	* dwarf2out.c (add_bound_info): If HOST_WIDE_INT is big enough,
+	then represent the bound as normal constant value.
+
 2014-03-19  Marek Polacek  <polacek@redhat.com>
 
 	PR sanitizer/60569
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 2b584a5..9f8b3b0 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -16198,21 +16198,29 @@ add_bound_info (dw_die_ref subrange_die, enum dwarf_attribute bound_attr, tree b
 	    && tree_to_shwi (bound) == dflt)
 	  ;
 
-	/* Otherwise represent the bound as an unsigned value with the
-	   precision of its type.  The precision and signedness of the
-	   type will be necessary to re-interpret it unambiguously.  */
-	else if (prec < HOST_BITS_PER_WIDE_INT)
+	/* If HOST_WIDE_INT is big enough then represent the bound as
+	   a constant value.  Note that we need to make sure the type
+	   is signed or unsigned.  We cannot just add an unsigned
+	   constant if the value itself is positive.  Some DWARF
+	   consumers will lookup the bounds type and then sign extend
+	   any unsigned values found for signed types.  This is only
+	   for DW_AT_lower_bound, normally unsigned values
+	   (DW_FORM_data[1248]) are assumed to not need
+	   sign-extension.  */
+	else if (prec <= HOST_BITS_PER_WIDE_INT
+		 || TREE_INT_CST_HIGH (bound) == 0)
 	  {
-	    unsigned HOST_WIDE_INT mask
-	      = ((unsigned HOST_WIDE_INT) 1 << prec) - 1;
-	    add_AT_unsigned (subrange_die, bound_attr,
-		  	     TREE_INT_CST_LOW (bound) & mask);
+	    if (TYPE_UNSIGNED (TREE_TYPE (bound)))
+	      add_AT_unsigned (subrange_die, bound_attr,
+			       TREE_INT_CST_LOW (bound));
+	    else
+	      add_AT_int (subrange_die, bound_attr, TREE_INT_CST_LOW (bound));
 	  }
-	else if (prec == HOST_BITS_PER_WIDE_INT
-		 || TREE_INT_CST_HIGH (bound) == 0)
-	  add_AT_unsigned (subrange_die, bound_attr,
-		  	   TREE_INT_CST_LOW (bound));
 	else
+	  /* Otherwise represent the bound as an unsigned value with
+	     the precision of its type.  The precision and signedness
+	     of the type will be necessary to re-interpret it
+	     unambiguously.  */
 	  add_AT_double (subrange_die, bound_attr, TREE_INT_CST_HIGH (bound),
 		         TREE_INT_CST_LOW (bound));
       }
-- 
1.7.1