(grokdeclarator): Convert to sizetype when manipulating size of array

and use care to avoid mixed-type operations.

From-SVN: r6787

diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index 7efb423bc16c5af907f5d1f75a5a56542f0a1948..66ca34866942f95e0d5d9ff5e9e0a6a1e795a633 100644 (file)
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -4265,21 +4265,25 @@ grokdeclarator (declarator, declspecs, decl_context, initialized)
                  error ("size of array `%s' has non-integer type", name);
                  size = integer_one_node;
                }
+
              if (pedantic && integer_zerop (size))
                pedwarn ("ANSI C forbids zero-size array `%s'", name);
+
              if (TREE_CODE (size) == INTEGER_CST)
                {
                  constant_expression_warning (size);
-                 if (INT_CST_LT (size, integer_zero_node))
+                 if (tree_int_cst_sgn (size) < 0)
                    {
                      error ("size of array `%s' is negative", name);
                      size = integer_one_node;
                    }
-                 itype = build_index_type (size_binop (MINUS_EXPR, size,
-                                                       size_one_node));
                }
              else
                {
+                 /* Make sure the array size remains visibly nonconstant
+                    even if it is (eg) a const variable with known value.  */
+                 size_varies = 1;
+
                  if (pedantic)
                    {
                      if (TREE_CONSTANT (size))
@@ -4287,14 +4291,16 @@ grokdeclarator (declarator, declspecs, decl_context, initialized)
                      else
                        pedwarn ("ANSI C forbids variable-size array `%s'", name);
                    }
-                 itype = build_binary_op (MINUS_EXPR, size, integer_one_node,
-                                          1);
-                 /* Make sure the array size remains visibly nonconstant
-                    even if it is (eg) a const variable with known value.  */
-                 size_varies = 1;
-                 itype = variable_size (itype);
-                 itype = build_index_type (itype);
                }
+
+             /* Convert size to sizetype, so that if it is a variable
+                the computations will be done in the proper mode.  */
+             itype = fold (build (MINUS_EXPR, sizetype,
+                                  convert (sizetype, size), size_one_node));
+
+             if (size_varies)
+               itype = variable_size (itype);
+             itype = build_index_type (itype);
            }
 
 #if 0 /* This had bad results for pointers to arrays, as in