decl.c (gnat_to_gnu_entity): Factor out common predicate.

	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Array_Subtype>: Factor
	out common predicate.  Use the maximum to compute the upper bound of
	the index type only when it is not wider than sizetype.  Perform the
	comparison in the index type for the generic expression.  Use real
	precision to decide whether to generate special types for debugging
	information.

From-SVN: r148964

4 files changed, 66 insertions, 20 deletions

diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 5e09f44..bb576e8 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,3 +1,12 @@
+2009-06-26  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Array_Subtype>: Factor
+	out common predicate.  Use the maximum to compute the upper bound of
+	the index type only when it is not wider than sizetype.  Perform the
+	comparison in the index type for the generic expression.  Use real
+	precision to decide whether to generate special types for debugging
+	information.
+
 2009-06-26  Matthew Gingell  <gingell@adacore.com>
 
 	* adaint.c: Do not use the dummy version of convert_addresses on LynxOS
@@ -13,6 +22,15 @@
 
 2009-06-26  Eric Botcazou  <ebotcazou@adacore.com>
 
+	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Array_Subtype>: Factor
+	out common predicate.  Use the maximum to compute the upper bound of
+	the index type only when it is not wider than sizetype.  Perform the
+	comparison in the index type for the generic expression.  Use real
+	precision to decide whether to generate special types for debugging
+	information.
+
+2009-06-26  Eric Botcazou  <ebotcazou@adacore.com>
+
 	* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Array_Type>: Pass
 	correct arguments to create_field_decl.  Remove redundant iteration.
 	Rewrite computation of the maximum size.
diff --git a/gcc/ada/gcc-interface/decl.c b/gcc/ada/gcc-interface/decl.c
index 5f15cd6..08e9a7d 100644
--- a/gcc/ada/gcc-interface/decl.c
+++ b/gcc/ada/gcc-interface/decl.c
@@ -2143,6 +2143,12 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 	       gnat_base_index = Next_Index (gnat_base_index))
 	    {
 	      tree gnu_index_type = get_unpadded_type (Etype (gnat_index));
+	      tree prec = TYPE_RM_SIZE (gnu_index_type);
+	      const bool wider_p
+		= (compare_tree_int (prec, TYPE_PRECISION (sizetype)) > 0
+		   || (compare_tree_int (prec, TYPE_PRECISION (sizetype)) == 0
+		       && TYPE_UNSIGNED (gnu_index_type)
+			  != TYPE_UNSIGNED (sizetype)));
 	      tree gnu_orig_min = TYPE_MIN_VALUE (gnu_index_type);
 	      tree gnu_orig_max = TYPE_MAX_VALUE (gnu_index_type);
 	      tree gnu_min = convert (sizetype, gnu_orig_min);
@@ -2167,10 +2173,7 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 
 	      /* Similarly, if one of the values overflows in sizetype and the
 		 range is null, use 1..0 for the sizetype bounds.  */
-	      else if ((TYPE_PRECISION (gnu_index_type)
-			> TYPE_PRECISION (sizetype)
-		        || TYPE_UNSIGNED (gnu_index_type)
-			   != TYPE_UNSIGNED (sizetype))
+	      else if (wider_p
 		       && TREE_CODE (gnu_min) == INTEGER_CST
 		       && TREE_CODE (gnu_max) == INTEGER_CST
 		       && (TREE_OVERFLOW (gnu_min) || TREE_OVERFLOW (gnu_max))
@@ -2184,10 +2187,7 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 	      /* If the minimum and maximum values both overflow in sizetype,
 		 but the difference in the original type does not overflow in
 		 sizetype, ignore the overflow indication.  */
-	      else if ((TYPE_PRECISION (gnu_index_type)
-			> TYPE_PRECISION (sizetype)
-			|| TYPE_UNSIGNED (gnu_index_type)
-			   != TYPE_UNSIGNED (sizetype))
+	      else if (wider_p
 		       && TREE_CODE (gnu_min) == INTEGER_CST
 		       && TREE_CODE (gnu_max) == INTEGER_CST
 		       && TREE_OVERFLOW (gnu_min) && TREE_OVERFLOW (gnu_max)
@@ -2209,9 +2209,11 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 		     "superflat" case.  There are three ways to do this.  If
 		     we can prove that the array can never be superflat, we
 		     can just use the high bound of the index subtype.  If we
-		     can prove that the low bound minus one can't overflow,
-		     we can do this as MAX (hb, lb - 1).  Otherwise, we have
-		     to use the expression hb >= lb ? hb : lb - 1.  */
+		     can prove that the low bound minus one and the high bound
+		     can't overflow, we can do this as MAX (hb, lb - 1).  But,
+		     otherwise, we have to use (hb >= lb) ? hb : lb - 1.  Note
+		     that the comparison must be done in the original index
+		     type, to avoid any overflow during the conversion.  */
 		  gnu_high = size_binop (MINUS_EXPR, gnu_min, size_one_node);
 
 		  /* If gnu_high is a constant that has overflowed, the array
@@ -2220,12 +2222,9 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 		      && TREE_OVERFLOW (gnu_high))
 		    gnu_high = gnu_max;
 
-		  /* gnu_high cannot overflow if the subtype is unsigned and
-		     sizetype is signed, or if it is a constant that hasn't
-		     overflowed.  */
-		  else if ((TYPE_UNSIGNED (gnu_index_type)
-			    && !TYPE_UNSIGNED (sizetype))
-			   || TREE_CODE (gnu_high) == INTEGER_CST)
+		  /* If the index type is not wider and gnu_high is a constant
+		     that hasn't overflowed, we can use the maximum.  */
+		  else if (!wider_p && TREE_CODE (gnu_high) == INTEGER_CST)
 		    gnu_high = size_binop (MAX_EXPR, gnu_max, gnu_high);
 
 		  else
@@ -2233,7 +2232,8 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 		      = build_cond_expr (sizetype,
 					 build_binary_op (GE_EXPR,
 							  integer_type_node,
-							  gnu_max, gnu_min),
+							  gnu_orig_max,
+							  gnu_orig_min),
 					 gnu_max, gnu_high);
 		}
 
@@ -2306,8 +2306,7 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, int definition)
 		      && TREE_CODE (TREE_TYPE (gnu_index_type))
 			 != INTEGER_TYPE)
 		  || TYPE_BIASED_REPRESENTATION_P (gnu_index_type)
-		  || (TYPE_PRECISION (gnu_index_type)
-		      > TYPE_PRECISION (sizetype)))
+		  || compare_tree_int (prec, TYPE_PRECISION (sizetype)) > 0)
 		need_index_type_struct = true;
 	    }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 172746f..95ae982 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2009-06-26  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gnat.dg/array6.adb: New test.
+
 2009-06-25  Ian Lance Taylor  <iant@google.com>
 
 	* g++.dg/warn/Wsign-compare-3.C: New testcase.
diff --git a/gcc/testsuite/gnat.dg/array6.adb b/gcc/testsuite/gnat.dg/array6.adb
new file mode 100644
index 0000000..1cc9d10
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/array6.adb
@@ -0,0 +1,25 @@
+-- { dg-do run }
+
+with Interfaces; use Interfaces;
+
+procedure Array6 is
+
+   type buf_t is array (unsigned_32 range <>) of character;
+   type v_str_t (first, last : unsigned_32) is
+      record
+         buf : buf_t (first .. last) := (others => ' ');
+      end record;
+   type v_str_ptr_t is access all v_str_t;
+
+   v_str : v_str_ptr_t;
+
+   function build_v_str (f, l : unsigned_32) return v_str_ptr_t is
+      vp : v_str_ptr_t := new v_str_t (f, l);
+   begin
+      return vp;
+   end;
+
+begin
+   v_str := build_v_str (unsigned_32'last/2 - 256,
+                         unsigned_32'last/2 + 1024*1024);
+end;