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re PR c++/69261 (Copying char arrays during constexpr evaluation does not work reliably)

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PR c++/69261
	* constexpr.c (find_array_ctor_elt): Handle splitting RANGE_EXPR.

From-SVN: r232370
This commit is contained in:
Jason Merrill 2016-01-14 10:32:31 -05:00 committed by Jason Merrill
parent 73e48cb322
commit a7ccb9e722
3 changed files with 113 additions and 2 deletions
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5
gcc/cp/ChangeLog
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@ -1,3 +1,8 @@
2016-01-14 Jason Merrill <jason@redhat.com>
PR c++/69261
* constexpr.c (find_array_ctor_elt): Handle splitting RANGE_EXPR.
2016-01-12 Marek Polacek <polacek@redhat.com>
PR c++/68979

47
gcc/cp/constexpr.c
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@ -1725,14 +1725,57 @@ find_array_ctor_elt (tree ary, tree dindex, bool insert = false)
while (begin != end)
{
unsigned HOST_WIDE_INT middle = (begin + end) / 2;
constructor_elt &elt = (*elts)[middle];
tree idx = elt.index;
int cmp = array_index_cmp (dindex, (*elts)[middle].index);
int cmp = array_index_cmp (dindex, idx);
if (cmp < 0)
end = middle;
else if (cmp > 0)
begin = middle + 1;
else
return middle;
{
if (insert && TREE_CODE (idx) == RANGE_EXPR)
{
/* We need to split the range. */
constructor_elt e;
tree lo = TREE_OPERAND (idx, 0);
tree hi = TREE_OPERAND (idx, 1);
if (tree_int_cst_lt (lo, dindex))
{
/* There are still some lower elts; shorten the range. */
tree new_hi = int_const_binop (MINUS_EXPR, dindex,
size_one_node);
if (tree_int_cst_equal (lo, new_hi))
/* Only one element left, no longer a range. */
elt.index = lo;
else
TREE_OPERAND (idx, 1) = new_hi;
/* Append the element we want to insert. */
++middle;
e.index = dindex;
e.value = unshare_expr (elt.value);
vec_safe_insert (CONSTRUCTOR_ELTS (ary), middle, e);
}
else
/* No lower elts, the range elt is now ours. */
elt.index = dindex;
if (tree_int_cst_lt (dindex, hi))
{
/* There are still some higher elts; append a range. */
tree new_lo = int_const_binop (PLUS_EXPR, dindex,
size_one_node);
if (tree_int_cst_equal (new_lo, hi))
e.index = hi;
else
e.index = build2 (RANGE_EXPR, sizetype, new_lo, hi);
e.value = unshare_expr (elt.value);
vec_safe_insert (CONSTRUCTOR_ELTS (ary), middle+1, e);
}
}
return middle;
}
}
if (insert)

63
gcc/testsuite/g++.dg/cpp1y/constexpr-array2.C Normal file
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@ -0,0 +1,63 @@
// PR c++/69261
// { dg-do run { target c++14 } }
typedef __SIZE_TYPE__ size_t;
template <size_t N>
struct S
{
constexpr S() = default;
template<size_t M>
constexpr S (char const (&d)[M]) : data { 0 }
{
static_assert (M <= N, "size!");
for (size_t i = 0; i != M; i++)
data[i] = d[i];
}
char data[N];
};
template <int N>
constexpr S<N>
s (char const (&d)[N])
{
S<N> c {};
for (size_t i = 0; i != N; i++)
c.data[i] = d[i];
return c;
}
template <size_t N, size_t M>
constexpr auto
concat (S<N> const& s1, S<M> const& s2)
{
S<N+M-1> s (s1.data);
for (size_t i = 0; i != M; i++)
s.data[N + i - 1] = s2.data[i];
return s;
}
template <size_t N, size_t M>
constexpr auto
concat (char const (&x)[N], char const (&y)[M])
{
S<N+M-1> tmp { x };
for (size_t i = 0; i != M; i++)
tmp.data[N+i-1] = y[i];
return tmp;
}
int
main ()
{
auto constexpr s1 = s ("bla");
auto constexpr s2 = s ("blub");
S<8> constexpr s1s2 = concat (s1, s2);
auto constexpr c = concat ("bla", "blub");
if (__builtin_strcmp (s1.data, "bla")
|| __builtin_strcmp (s2.data, "blub")
|| __builtin_strcmp (s1s2.data, "blablub")
|| __builtin_strcmp (c.data, "blablub"))
__builtin_abort ();
}