tree.c (valid_constant_size_p): New function.

2012-05-02  Richard Guenther  <rguenther@suse.de>

	* tree.c (valid_constant_size_p): New function.
	* tree.h (valid_constant_size_p): Declare.
	* cfgexpand.c (expand_one_var): Adjust check for too large
	variables by using valid_constant_size_p.
	* varasm.c (assemble_variable): Likewise.

	c/
	* c-decl.c (grokdeclarator): Properly check for sizes that
	cover more than half of the address-space.

	cp/
	* decl.c (grokdeclarator): Properly check for sizes that
	cover more than half of the address-space.

2012-05-02  Richard Guenther  <rguenther@suse.de>

	* fold-const.c (div_if_zero_remainder): sizetypes no longer
	sign-extend.
	(int_const_binop_1): New worker for int_const_binop with
	overflowable parameter.  Pass it through
	to force_fit_type_double.
	(int_const_binop): Wrap around int_const_binop_1 with overflowable
	equal to one.
	(size_binop_loc): Call int_const_binop_1 with overflowable equal
	to minus one, forcing overflow detection for even unsigned types.
	(extract_muldiv_1): Remove bogus TYPE_IS_SIZETYPE special-casing.
	(fold_binary_loc): Call try_move_mult_to_index with signed offset.
	* stor-layout.c (initialize_sizetypes): sizetypes no longer
	sign-extend.
	(layout_type): For zero-sized arrays ignore overflow on the
	size calculations.
	* tree-ssa-ccp.c (bit_value_unop_1): Likewise.
	(bit_value_binop_1): Likewise.
	* tree.c (double_int_to_tree): Likewise.
	(double_int_fits_to_tree_p): Likewise.
	(force_fit_type_double): Likewise.
	(host_integerp): Likewise.
	(int_fits_type_p): Likewise.
	* varasm.c (output_constructor_regular_field): Sign-extend the
	field-offset to cater for negative offsets produced by the Ada frontend.
	* omp-low.c (extract_omp_for_data): Convert the loop step to
	signed for pointer adjustments.

	* g++.dg/tree-ssa/pr19807.C: Adjust.

From-SVN: r187042

1 files changed, 31 insertions, 15 deletions

diff --git a/gcc/stor-layout.c b/gcc/stor-layout.c
index e72e7f39091..12a6c13a6b8 100644
--- a/gcc/stor-layout.c
+++ b/gcc/stor-layout.c
@@ -2182,11 +2182,37 @@ layout_type (tree type)
 	       that (possible) negative values are handled appropriately
 	       when determining overflow.  */
 	    else
-	      length
-		= fold_convert (sizetype,
-				size_binop (PLUS_EXPR,
-					    build_int_cst (TREE_TYPE (lb), 1),
-					    size_binop (MINUS_EXPR, ub, lb)));
+	      {
+		/* ???  When it is obvious that the range is signed
+		   represent it using ssizetype.  */
+		if (TREE_CODE (lb) == INTEGER_CST
+		    && TREE_CODE (ub) == INTEGER_CST
+		    && TYPE_UNSIGNED (TREE_TYPE (lb))
+		    && tree_int_cst_lt (ub, lb))
+		  {
+		    lb = double_int_to_tree
+			   (ssizetype,
+			    double_int_sext (tree_to_double_int (lb),
+					     TYPE_PRECISION (TREE_TYPE (lb))));
+		    ub = double_int_to_tree
+			   (ssizetype,
+			    double_int_sext (tree_to_double_int (ub),
+					     TYPE_PRECISION (TREE_TYPE (ub))));
+		  }
+		length
+		  = fold_convert (sizetype,
+				  size_binop (PLUS_EXPR,
+					      build_int_cst (TREE_TYPE (lb), 1),
+					      size_binop (MINUS_EXPR, ub, lb)));
+	      }
+
+	    /* If we arrived at a length of zero ignore any overflow
+	       that occured as part of the calculation.  There exists
+	       an association of the plus one where that overflow would
+	       not happen.  */
+	    if (integer_zerop (length)
+		&& TREE_OVERFLOW (length))
+	      length = size_zero_node;
 
 	    TYPE_SIZE (type) = size_binop (MULT_EXPR, element_size,
 					   fold_convert (bitsizetype,
@@ -2453,11 +2479,6 @@ initialize_sizetypes (void)
   TYPE_SIZE_UNIT (sizetype) = size_int (GET_MODE_SIZE (TYPE_MODE (sizetype)));
   set_min_and_max_values_for_integral_type (sizetype, precision,
 					    /*is_unsigned=*/true);
-  /* sizetype is unsigned but we need to fix TYPE_MAX_VALUE so that it is
-     sign-extended in a way consistent with force_fit_type.  */
-  TYPE_MAX_VALUE (sizetype)
-    = double_int_to_tree (sizetype,
-			  tree_to_double_int (TYPE_MAX_VALUE (sizetype)));
 
   SET_TYPE_MODE (bitsizetype, smallest_mode_for_size (bprecision, MODE_INT));
   TYPE_ALIGN (bitsizetype) = GET_MODE_ALIGNMENT (TYPE_MODE (bitsizetype));
@@ -2466,11 +2487,6 @@ initialize_sizetypes (void)
     = size_int (GET_MODE_SIZE (TYPE_MODE (bitsizetype)));
   set_min_and_max_values_for_integral_type (bitsizetype, bprecision,
 					    /*is_unsigned=*/true);
-  /* bitsizetype is unsigned but we need to fix TYPE_MAX_VALUE so that it is
-     sign-extended in a way consistent with force_fit_type.  */
-  TYPE_MAX_VALUE (bitsizetype)
-    = double_int_to_tree (bitsizetype,
-			  tree_to_double_int (TYPE_MAX_VALUE (bitsizetype)));
 
   /* Create the signed variants of *sizetype.  */
   ssizetype = make_signed_type (TYPE_PRECISION (sizetype));