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.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@187042 138bc75d-0d04-0410-961f-82ee72b054a4

14 files changed, 140 insertions, 92 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f9b8a6e84f2..48539591560 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,43 @@
+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.
+
+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-decl.c (grokdeclarator): Properly check for sizes that
+	cover more than half of the address-space.
+
 2012-05-02  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/53163
diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index 158b3ad0f19..3153cf4e183 100644
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -5811,12 +5811,12 @@ grokdeclarator (const struct c_declarator *declarator,
 	}
     }
 
-  /* Did array size calculations overflow?  */
-
+  /* Did array size calculations overflow or does the array cover more
+     than half of the address-space?  */
   if (TREE_CODE (type) == ARRAY_TYPE
       && COMPLETE_TYPE_P (type)
       && TREE_CODE (TYPE_SIZE_UNIT (type)) == INTEGER_CST
-      && TREE_OVERFLOW (TYPE_SIZE_UNIT (type)))
+      && ! valid_constant_size_p (TYPE_SIZE_UNIT (type)))
     {
       if (name)
 	error_at (loc, "size of array %qE is too large", name);
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 9de3e51c673..4c27e762df5 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -1241,8 +1241,9 @@ expand_one_var (tree var, bool toplevel, bool really_expand)
       if (really_expand)
         expand_one_register_var (origvar);
     }
-  else if (!host_integerp (DECL_SIZE_UNIT (var), 1))
+  else if (! valid_constant_size_p (DECL_SIZE_UNIT (var)))
     {
+      /* Reject variables which cover more than half of the address-space.  */
       if (really_expand)
 	{
 	  error ("size of variable %q+D is too large", var);
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index e52149f023d..6b0e57cedb5 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2012-05-02  Richard Guenther  <rguenther@suse.de>
+
+	* decl.c (grokdeclarator): Properly check for sizes that
+	cover more than half of the address-space.
+
 2012-04-30  Marc Glisse  <marc.glisse@inria.fr>
 
 	PR c++/51033
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 40818a3f3ff..108b51531d4 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -9672,12 +9672,12 @@ grokdeclarator (const cp_declarator *declarator,
         error ("non-parameter %qs cannot be a parameter pack", name);
     }
 
-  /* Did array size calculations overflow?  */
-
+  /* Did array size calculations overflow or does the array cover more
+     than half of the address-space?  */
   if (TREE_CODE (type) == ARRAY_TYPE
       && COMPLETE_TYPE_P (type)
       && TREE_CODE (TYPE_SIZE_UNIT (type)) == INTEGER_CST
-      && TREE_OVERFLOW (TYPE_SIZE_UNIT (type)))
+      && ! valid_constant_size_p (TYPE_SIZE_UNIT (type)))
     {
       error ("size of array %qs is too large", name);
       /* If we proceed with the array type as it is, we'll eventually
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 41081ff919c..fe12942d981 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -191,9 +191,6 @@ div_if_zero_remainder (enum tree_code code, const_tree arg1, const_tree arg2)
      does the correct thing for POINTER_PLUS_EXPR where we want
      a signed division.  */
   uns = TYPE_UNSIGNED (TREE_TYPE (arg2));
-  if (TREE_CODE (TREE_TYPE (arg2)) == INTEGER_TYPE
-      && TYPE_IS_SIZETYPE (TREE_TYPE (arg2)))
-    uns = false;
 
   quo = double_int_divmod (tree_to_double_int (arg1),
 			   tree_to_double_int (arg2),
@@ -935,8 +932,9 @@ int_binop_types_match_p (enum tree_code code, const_tree type1, const_tree type2
    to produce a new constant.  Return NULL_TREE if we don't know how
    to evaluate CODE at compile-time.  */
 
-tree
-int_const_binop (enum tree_code code, const_tree arg1, const_tree arg2)
+static tree
+int_const_binop_1 (enum tree_code code, const_tree arg1, const_tree arg2,
+		   int overflowable)
 {
   double_int op1, op2, res, tmp;
   tree t;
@@ -1078,13 +1076,19 @@ int_const_binop (enum tree_code code, const_tree arg1, const_tree arg2)
       return NULL_TREE;
     }
 
-  t = force_fit_type_double (TREE_TYPE (arg1), res, 1,
+  t = force_fit_type_double (TREE_TYPE (arg1), res, overflowable,
 			     ((!uns || is_sizetype) && overflow)
 			     | TREE_OVERFLOW (arg1) | TREE_OVERFLOW (arg2));
 
   return t;
 }
 
+tree
+int_const_binop (enum tree_code code, const_tree arg1, const_tree arg2)
+{
+  return int_const_binop_1 (code, arg1, arg2, 1);
+}
+
 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
    constant.  We assume ARG1 and ARG2 have the same data type, or at least
    are the same kind of constant and the same machine mode.  Return zero if
@@ -1423,8 +1427,10 @@ size_binop_loc (location_t loc, enum tree_code code, tree arg0, tree arg1)
 	    return arg1;
 	}
 
-      /* Handle general case of two integer constants.  */
-      return int_const_binop (code, arg0, arg1);
+      /* Handle general case of two integer constants.  For sizetype
+         constant calculations we always want to know about overflow,
+	 even in the unsigned case.  */
+      return int_const_binop_1 (code, arg0, arg1, -1);
     }
 
   return fold_build2_loc (loc, code, type, arg0, arg1);
@@ -5908,11 +5914,9 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
 	 multiple of the other, in which case we replace this with either an
 	 operation or CODE or TCODE.
 
-	 If we have an unsigned type that is not a sizetype, we cannot do
-	 this since it will change the result if the original computation
-	 overflowed.  */
-      if ((TYPE_OVERFLOW_UNDEFINED (ctype)
-	   || (TREE_CODE (ctype) == INTEGER_TYPE && TYPE_IS_SIZETYPE (ctype)))
+	 If we have an unsigned type, we cannot do this since it will change
+	 the result if the original computation overflowed.  */
+      if (TYPE_OVERFLOW_UNDEFINED (ctype)
 	  && ((code == MULT_EXPR && tcode == EXACT_DIV_EXPR)
 	      || (tcode == MULT_EXPR
 		  && code != TRUNC_MOD_EXPR && code != CEIL_MOD_EXPR
@@ -9971,7 +9975,8 @@ fold_binary_loc (location_t loc,
       if (TREE_CODE (arg0) == ADDR_EXPR)
 	{
 	  tem = try_move_mult_to_index (loc, arg0,
-					fold_convert_loc (loc, sizetype, arg1));
+					fold_convert_loc (loc,
+							  ssizetype, arg1));
 	  if (tem)
 	    return fold_convert_loc (loc, type, tem);
 	}
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index ec1a5522d7f..f6b62438dce 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -336,9 +336,11 @@ extract_omp_for_data (gimple for_stmt, struct omp_for_data *fd,
       switch (TREE_CODE (t))
 	{
 	case PLUS_EXPR:
-	case POINTER_PLUS_EXPR:
 	  loop->step = TREE_OPERAND (t, 1);
 	  break;
+	case POINTER_PLUS_EXPR:
+	  loop->step = fold_convert (ssizetype, TREE_OPERAND (t, 1));
+	  break;
 	case MINUS_EXPR:
 	  loop->step = TREE_OPERAND (t, 1);
 	  loop->step = fold_build1_loc (loc,
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));
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b2055433beb..95650152046 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2012-05-02  Richard Guenther  <rguenther@suse.de>
+
+	* g++.dg/tree-ssa/pr19807.C: Adjust.
+
 2012-05-02  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/53163
diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr19807.C b/gcc/testsuite/g++.dg/tree-ssa/pr19807.C
index bba79a9d150..0eeeb18abda 100644
--- a/gcc/testsuite/g++.dg/tree-ssa/pr19807.C
+++ b/gcc/testsuite/g++.dg/tree-ssa/pr19807.C
@@ -25,6 +25,6 @@ void bar(int i)
    Simply test for the existence of +1 and -1 once, which also ensures
    the above.  If the addition/subtraction would be applied to the
    pointer we would instead see +-4 (or 8, depending on sizeof(int)).  */
-/* { dg-final { scan-tree-dump-times "\\\+ -1;" 1 "optimized" } } */
+/* { dg-final { scan-tree-dump "\\\+ (0x0f*|18446744073709551615|4294967295|-1);" "optimized" } } */
 /* { dg-final { scan-tree-dump-times "\\\+ 1;" 1 "optimized" } } */
 /* { dg-final { cleanup-tree-dump "optimized" } } */
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 4e86b8db0c3..1257b8bf7ba 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -1101,14 +1101,12 @@ bit_value_unop_1 (enum tree_code code, tree type,
 	bool uns;
 
 	/* First extend mask and value according to the original type.  */
-	uns = (TREE_CODE (rtype) == INTEGER_TYPE && TYPE_IS_SIZETYPE (rtype)
-	       ? 0 : TYPE_UNSIGNED (rtype));
+	uns = TYPE_UNSIGNED (rtype);
 	*mask = double_int_ext (rmask, TYPE_PRECISION (rtype), uns);
 	*val = double_int_ext (rval, TYPE_PRECISION (rtype), uns);
 
 	/* Then extend mask and value according to the target type.  */
-	uns = (TREE_CODE (type) == INTEGER_TYPE && TYPE_IS_SIZETYPE (type)
-	       ? 0 : TYPE_UNSIGNED (type));
+	uns = TYPE_UNSIGNED (type);
 	*mask = double_int_ext (*mask, TYPE_PRECISION (type), uns);
 	*val = double_int_ext (*val, TYPE_PRECISION (type), uns);
 	break;
@@ -1130,8 +1128,7 @@ bit_value_binop_1 (enum tree_code code, tree type,
 		   tree r1type, double_int r1val, double_int r1mask,
 		   tree r2type, double_int r2val, double_int r2mask)
 {
-  bool uns = (TREE_CODE (type) == INTEGER_TYPE
-	      && TYPE_IS_SIZETYPE (type) ? 0 : TYPE_UNSIGNED (type));
+  bool uns = TYPE_UNSIGNED (type);
   /* Assume we'll get a constant result.  Use an initial varying value,
      we fall back to varying in the end if necessary.  */
   *mask = double_int_minus_one;
@@ -1198,13 +1195,6 @@ bit_value_binop_1 (enum tree_code code, tree type,
 	    }
 	  else if (shift < 0)
 	    {
-	      /* ???  We can have sizetype related inconsistencies in
-		 the IL.  */
-	      if ((TREE_CODE (r1type) == INTEGER_TYPE
-		   && (TYPE_IS_SIZETYPE (r1type)
-		       ? 0 : TYPE_UNSIGNED (r1type))) != uns)
-		break;
-
 	      shift = -shift;
 	      *mask = double_int_rshift (r1mask, shift,
 					 TYPE_PRECISION (type), !uns);
@@ -1316,12 +1306,7 @@ bit_value_binop_1 (enum tree_code code, tree type,
 	  break;
 
 	/* For comparisons the signedness is in the comparison operands.  */
-	uns = (TREE_CODE (r1type) == INTEGER_TYPE
-	       && TYPE_IS_SIZETYPE (r1type) ? 0 : TYPE_UNSIGNED (r1type));
-	/* ???  We can have sizetype related inconsistencies in the IL.  */
-	if ((TREE_CODE (r2type) == INTEGER_TYPE
-	     && TYPE_IS_SIZETYPE (r2type) ? 0 : TYPE_UNSIGNED (r2type)) != uns)
-	  break;
+	uns = TYPE_UNSIGNED (r1type);
 
 	/* If we know the most significant bits we know the values
 	   value ranges by means of treating varying bits as zero
diff --git a/gcc/tree.c b/gcc/tree.c
index 4623d3765e4..1ee3f1db51e 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -1062,10 +1062,7 @@ build_int_cst_type (tree type, HOST_WIDE_INT low)
 tree
 double_int_to_tree (tree type, double_int cst)
 {
-  /* Size types *are* sign extended.  */
-  bool sign_extended_type = (!TYPE_UNSIGNED (type)
-			     || (TREE_CODE (type) == INTEGER_TYPE
-				 && TYPE_IS_SIZETYPE (type)));
+  bool sign_extended_type = !TYPE_UNSIGNED (type);
 
   cst = double_int_ext (cst, TYPE_PRECISION (type), !sign_extended_type);
 
@@ -1079,9 +1076,7 @@ bool
 double_int_fits_to_tree_p (const_tree type, double_int cst)
 {
   /* Size types *are* sign extended.  */
-  bool sign_extended_type = (!TYPE_UNSIGNED (type)
-			     || (TREE_CODE (type) == INTEGER_TYPE
-				 && TYPE_IS_SIZETYPE (type)));
+  bool sign_extended_type = !TYPE_UNSIGNED (type);
 
   double_int ext
     = double_int_ext (cst, TYPE_PRECISION (type), !sign_extended_type);
@@ -1111,9 +1106,7 @@ force_fit_type_double (tree type, double_int cst, int overflowable,
   bool sign_extended_type;
 
   /* Size types *are* sign extended.  */
-  sign_extended_type = (!TYPE_UNSIGNED (type)
-                        || (TREE_CODE (type) == INTEGER_TYPE
-                            && TYPE_IS_SIZETYPE (type)));
+  sign_extended_type = !TYPE_UNSIGNED (type);
 
   /* If we need to set overflow flags, return a new unshared node.  */
   if (overflowed || !double_int_fits_to_tree_p(type, cst))
@@ -6553,9 +6546,7 @@ host_integerp (const_tree t, int pos)
 	       && (HOST_WIDE_INT) TREE_INT_CST_LOW (t) >= 0)
 	      || (! pos && TREE_INT_CST_HIGH (t) == -1
 		  && (HOST_WIDE_INT) TREE_INT_CST_LOW (t) < 0
-		  && (!TYPE_UNSIGNED (TREE_TYPE (t))
-		      || (TREE_CODE (TREE_TYPE (t)) == INTEGER_TYPE
-			  && TYPE_IS_SIZETYPE (TREE_TYPE (t)))))
+		  && !TYPE_UNSIGNED (TREE_TYPE (t)))
 	      || (pos && TREE_INT_CST_HIGH (t) == 0)));
 }
 
@@ -6850,6 +6841,20 @@ compare_tree_int (const_tree t, unsigned HOST_WIDE_INT u)
     return 1;
 }
 
+/* Return true if SIZE represents a constant size that is in bounds of
+   what the middle-end and the backend accepts (covering not more than
+   half of the address-space).  */
+
+bool
+valid_constant_size_p (const_tree size)
+{
+  if (! host_integerp (size, 1)
+      || TREE_OVERFLOW (size)
+      || tree_int_cst_sign_bit (size) != 0)
+    return false;
+  return true;
+}
+
 /* Return true if CODE represents an associative tree code.  Otherwise
    return false.  */
 bool
@@ -8276,18 +8281,6 @@ int_fits_type_p (const_tree c, const_tree type)
   dc = tree_to_double_int (c);
   unsc = TYPE_UNSIGNED (TREE_TYPE (c));
 
-  if (TREE_CODE (TREE_TYPE (c)) == INTEGER_TYPE
-      && TYPE_IS_SIZETYPE (TREE_TYPE (c))
-      && unsc)
-    /* So c is an unsigned integer whose type is sizetype and type is not.
-       sizetype'd integers are sign extended even though they are
-       unsigned. If the integer value fits in the lower end word of c,
-       and if the higher end word has all its bits set to 1, that
-       means the higher end bits are set to 1 only for sign extension.
-       So let's convert c into an equivalent zero extended unsigned
-       integer.  */
-    dc = double_int_zext (dc, TYPE_PRECISION (TREE_TYPE (c)));
-
 retry:
   type_low_bound = TYPE_MIN_VALUE (type);
   type_high_bound = TYPE_MAX_VALUE (type);
@@ -8306,10 +8299,6 @@ retry:
   if (type_low_bound && TREE_CODE (type_low_bound) == INTEGER_CST)
     {
       dd = tree_to_double_int (type_low_bound);
-      if (TREE_CODE (type) == INTEGER_TYPE
-	  && TYPE_IS_SIZETYPE (type)
-	  && TYPE_UNSIGNED (type))
-	dd = double_int_zext (dd, TYPE_PRECISION (type));
       if (unsc != TYPE_UNSIGNED (TREE_TYPE (type_low_bound)))
 	{
 	  int c_neg = (!unsc && double_int_negative_p (dc));
@@ -8331,10 +8320,6 @@ retry:
   if (type_high_bound && TREE_CODE (type_high_bound) == INTEGER_CST)
     {
       dd = tree_to_double_int (type_high_bound);
-      if (TREE_CODE (type) == INTEGER_TYPE
-	  && TYPE_IS_SIZETYPE (type)
-	  && TYPE_UNSIGNED (type))
-	dd = double_int_zext (dd, TYPE_PRECISION (type));
       if (unsc != TYPE_UNSIGNED (TREE_TYPE (type_high_bound)))
 	{
 	  int c_neg = (!unsc && double_int_negative_p (dc));
diff --git a/gcc/tree.h b/gcc/tree.h
index e719be2ed40..3d7fcabe142 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -4451,6 +4451,7 @@ extern bool tree_expr_nonnegative_warnv_p (tree, bool *);
 extern bool may_negate_without_overflow_p (const_tree);
 extern tree strip_array_types (tree);
 extern tree excess_precision_type (tree);
+extern bool valid_constant_size_p (const_tree);
 
 /* Construct various nodes representing fract or accum data types.  */
 
diff --git a/gcc/varasm.c b/gcc/varasm.c
index 03ac49b4677..ce9e3280364 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -1992,7 +1992,7 @@ assemble_variable (tree decl, int top_level ATTRIBUTE_UNUSED,
     return;
 
   if (! dont_output_data
-      && ! host_integerp (DECL_SIZE_UNIT (decl), 1))
+      && ! valid_constant_size_p (DECL_SIZE_UNIT (decl)))
     {
       error ("size of variable %q+D is too large", decl);
       return;
@@ -4773,9 +4773,13 @@ output_constructor_regular_field (oc_local_state *local)
 
   if (local->index != NULL_TREE)
     {
+      /* Perform the index calculation in modulo arithmetic but
+	 sign-extend the result because Ada has negative DECL_FIELD_OFFSETs
+	 but we are using an unsigned sizetype.  */
+      unsigned prec = TYPE_PRECISION (sizetype);
       double_int idx = double_int_sub (tree_to_double_int (local->index),
 				       tree_to_double_int (local->min_index));
-      gcc_assert (double_int_fits_in_shwi_p (idx));
+      idx = double_int_sext (idx, prec);
       fieldpos = (tree_low_cst (TYPE_SIZE_UNIT (TREE_TYPE (local->val)), 1)
 		  * idx.low);
     }