static bool
fold_const_significand (real_value *result, const real_value *arg,
const real_format *format)
{
switch (arg->cl)
{
case rvc_zero:
case rvc_nan:
case rvc_inf:
/* If arg is +-0, +-Inf or +-NaN, then return it. */
*result = *arg;
return true;
case rvc_normal:
/* For normal numbers, proceed iff radix == 2. */
if (format->b == 2)
{
*result = *arg;
/* In GCC, normalized significands are in the range [0.5, 1.0).
We want them to be [1.0, 2.0) so set the exponent to 1. */
SET_REAL_EXP (result, 1);
return true;
}
return false;
}
gcc_unreachable ();
}
tree
ubsan_instrument_float_cast (location_t loc, tree type, tree expr)
{
tree expr_type = TREE_TYPE (expr);
tree t, tt, fn, min, max;
enum machine_mode mode = TYPE_MODE (expr_type);
int prec = TYPE_PRECISION (type);
bool uns_p = TYPE_UNSIGNED (type);
/* Float to integer conversion first truncates toward zero, so
even signed char c = 127.875f; is not problematic.
Therefore, we should complain only if EXPR is unordered or smaller
or equal than TYPE_MIN_VALUE - 1.0 or greater or equal than
TYPE_MAX_VALUE + 1.0. */
if (REAL_MODE_FORMAT (mode)->b == 2)
{
/* For maximum, TYPE_MAX_VALUE might not be representable
in EXPR_TYPE, e.g. if TYPE is 64-bit long long and
EXPR_TYPE is IEEE single float, but TYPE_MAX_VALUE + 1.0 is
either representable or infinity. */
REAL_VALUE_TYPE maxval = dconst1;
SET_REAL_EXP (&maxval, REAL_EXP (&maxval) + prec - !uns_p);
real_convert (&maxval, mode, &maxval);
max = build_real (expr_type, maxval);
/* For unsigned, assume -1.0 is always representable. */
if (uns_p)
min = build_minus_one_cst (expr_type);
else
{
/* TYPE_MIN_VALUE is generally representable (or -inf),
but TYPE_MIN_VALUE - 1.0 might not be. */
REAL_VALUE_TYPE minval = dconstm1, minval2;
SET_REAL_EXP (&minval, REAL_EXP (&minval) + prec - 1);
real_convert (&minval, mode, &minval);
real_arithmetic (&minval2, MINUS_EXPR, &minval, &dconst1);
real_convert (&minval2, mode, &minval2);
if (real_compare (EQ_EXPR, &minval, &minval2)
&& !real_isinf (&minval))
{
/* If TYPE_MIN_VALUE - 1.0 is not representable and
rounds to TYPE_MIN_VALUE, we need to subtract
more. As REAL_MODE_FORMAT (mode)->p is the number
of base digits, we want to subtract a number that
will be 1 << (REAL_MODE_FORMAT (mode)->p - 1)
times smaller than minval. */
minval2 = dconst1;
gcc_assert (prec > REAL_MODE_FORMAT (mode)->p);
SET_REAL_EXP (&minval2,
REAL_EXP (&minval2) + prec - 1
- REAL_MODE_FORMAT (mode)->p + 1);
real_arithmetic (&minval2, MINUS_EXPR, &minval, &minval2);
real_convert (&minval2, mode, &minval2);
}
min = build_real (expr_type, minval2);
}
}
else if (REAL_MODE_FORMAT (mode)->b == 10)
{
/* For _Decimal128 up to 34 decimal digits, - sign,
dot, e, exponent. */
char buf[64];
mpfr_t m;
int p = REAL_MODE_FORMAT (mode)->p;
REAL_VALUE_TYPE maxval, minval;
/* Use mpfr_snprintf rounding to compute the smallest
representable decimal number greater or equal than
1 << (prec - !uns_p). */
mpfr_init2 (m, prec + 2);
mpfr_set_ui_2exp (m, 1, prec - !uns_p, GMP_RNDN);
mpfr_snprintf (buf, sizeof buf, "%.*RUe", p - 1, m);
decimal_real_from_string (&maxval, buf);
max = build_real (expr_type, maxval);
/* For unsigned, assume -1.0 is always representable. */
if (uns_p)
min = build_minus_one_cst (expr_type);
else
{
/* Use mpfr_snprintf rounding to compute the largest
representable decimal number less or equal than
(-1 << (prec - 1)) - 1. */
mpfr_set_si_2exp (m, -1, prec - 1, GMP_RNDN);
mpfr_sub_ui (m, m, 1, GMP_RNDN);
mpfr_snprintf (buf, sizeof buf, "%.*RDe", p - 1, m);
decimal_real_from_string (&minval, buf);
min = build_real (expr_type, minval);
}
mpfr_clear (m);
}
else
return NULL_TREE;
if (flag_sanitize_undefined_trap_on_error)
fn = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP), 0);
else
{
/* Create the __ubsan_handle_float_cast_overflow fn call. */
tree data = ubsan_create_data ("__ubsan_float_cast_overflow_data", NULL,
NULL, ubsan_type_descriptor (expr_type),
ubsan_type_descriptor (type), NULL_TREE);
enum built_in_function bcode
= flag_sanitize_recover
? BUILT_IN_UBSAN_HANDLE_FLOAT_CAST_OVERFLOW
: BUILT_IN_UBSAN_HANDLE_FLOAT_CAST_OVERFLOW_ABORT;
fn = builtin_decl_explicit (bcode);
fn = build_call_expr_loc (loc, fn, 2,
build_fold_addr_expr_loc (loc, data),
ubsan_encode_value (expr, false));
}
t = fold_build2 (UNLE_EXPR, boolean_type_node, expr, min);
tt = fold_build2 (UNGE_EXPR, boolean_type_node, expr, max);
return fold_build3 (COND_EXPR, void_type_node,
fold_build2 (TRUTH_OR_EXPR, boolean_type_node, t, tt),
fn, integer_zero_node);
}
