On 10/23/2017 11:00 AM, Richard Sandiford wrote:
+#if NUM_POLY_INT_COEFFS == 1
+extern inline __attribute__ ((__gnu_inline__)) poly_int64
+tree_to_poly_int64 (const_tree t)
I'm curious about the extern inline and __gnu_inline__ here and
not in poly_int_tree_p below. Am I correct in assuming that
the combination is a holdover from the days when GCC was compiled
using a C compiler, and that the way to write the same definition
in C++ 98 is simply:
inline poly_int64
tree_to_poly_int64 (const_tree t)
+{
+ gcc_assert (tree_fits_poly_int64_p (t));
+ return TREE_INT_CST_LOW (t);
+}
If yes, I would suggest to use the C++ form (and at some point,
changing the existing uses of the GCC/C idiom to the C++ form
as well).
Otherwise, if something requires the use of the C form I would
suggest to add a brief comment explaining it.
...
+
+inline bool
+poly_int_tree_p (const_tree t, poly_int64_pod *value)
+{
...
/* The tree and const_tree overload templates. */
namespace wi
{
+ class unextended_tree
+ {
+ private:
+ const_tree m_t;
+
+ public:
+ unextended_tree () {}
Defining no-op ctors is quite dangerous and error-prone. I suggest
to instead default initialize the member(s):
unextended_tree (): m_t () {}
Ditto everywhere else, such as in:
...
template <int N>
class extended_tree
{
@@ -5139,11 +5225,13 @@ extern bool anon_aggrname_p (const_tree)
const_tree m_t;
public:
+ extended_tree () {}
extended_tree (const_tree);
...
Index: gcc/tree.c
===================================================================
...
+
+/* Return true if T holds a polynomial pointer difference, storing it in
+ *VALUE if so. A true return means that T's precision is no greater
+ than 64 bits, which is the largest address space we support, so *VALUE
+ never loses precision. However, the signedness of the result is
+ somewhat arbitrary, since if B lives near the end of a 64-bit address
+ range and A lives near the beginning, B - A is a large positive value
+ outside the range of int64_t. A - B is likewise a large negative value
+ outside the range of int64_t. All the pointer difference really
+ gives is a raw pointer-sized bitstring that can be added to the first
+ pointer value to get the second. */
I'm not sure I understand the comment about the sign correctly, but
if I do, I don't think it's correct.
Because their difference wouldn't representable in any basic integer
type (i.,e., in ptrdiff_t) the pointers described above could never
point to the same object (or array), and so their difference is not
meaningful. C/C++ only define the semantics of a difference between
pointers to the same object. That restricts the size of the largest
possible object typically to SIZE_MAX / 2, or at most SIZE_MAX on
the handful of targets where ptrdiff_t has greater precision than
size_t. But even on those targets, the difference between any two
pointers to the same object must be representable in ptrdiff_t,
including the sign.
+bool
+ptrdiff_tree_p (const_tree t, poly_int64_pod *value)
+{
Martin
