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Fix strtod subnormal rounding (bug 30220)
As reported in bug 30220, the implementation of strtod-family functions has a bug in the following case: the input string would, with infinite exponent range, take one more bit to represent than is available in the normal precision of the return type; the value represented is in the subnormal range; and there are no nonzero bits in the value, below those that can be represented in subnormal precision, other than the least significant bit and possibly the 0.5ulp bit. In this case, round_and_return ends up discarding the least significant bit. Fix by saving that bit to merge into more_bits (it can't be merged in at the time it's computed, because more_bits mustn't include this bit in the case of after-rounding tininess detection checking if the result is still subnormal when rounded to normal precision, so merging this bit into more_bits needs to take place after that check). Tested for x86_64.
This commit is contained in:
Joseph Myers
parent
d73ed2601b
commit
457622c2fa
@ -222,6 +222,7 @@ round_and_return (mp_limb_t *retval, intmax_t exponent, int negative,
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mp_size_t shift = MIN_EXP - 1 - exponent;
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bool is_tiny = true;
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bool old_half_bit = (round_limb & (((mp_limb_t) 1) << round_bit)) != 0;
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more_bits |= (round_limb & ((((mp_limb_t) 1) << round_bit) - 1)) != 0;
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if (shift == MANT_DIG)
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@ -292,6 +293,7 @@ round_and_return (mp_limb_t *retval, intmax_t exponent, int negative,
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round_bit = shift - 1;
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(void) __mpn_rshift (retval, retval, RETURN_LIMB_SIZE, shift);
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}
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more_bits |= old_half_bit;
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/* This is a hook for the m68k long double format, where the
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exponent bias is the same for normalized and denormalized
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numbers. */
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@ -265,3 +265,15 @@
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1.000000000000000000000000000000000385185988877447170611195588516985463707620329643077639047987759113311767578125
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1.0000000000000000000000000000000001925929944387235853055977942584927318538101648215388195239938795566558837890625
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1.00000000000000000000000000000000009629649721936179265279889712924636592690508241076940976199693977832794189453125
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0x30000002222225p-1077
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0x0.7fffffffffffeap-1022
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0x0.7fffffffffffe9p-1022
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0x0.7ffffd4p-126
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0x0.7ffffffffffffffd4p-16382
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0x0.7ffffffffffffffd4p-16383
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0x0.7ffffffffffffffffffffffffffeap-16382
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0x0.7000004p-126
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0x0.70000000000002p-1022
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0x0.70000000000000004p-16382
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0x0.70000000000000004p-16383
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0x0.70000000000000000000000000002p-16382
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@ -15437,4 +15437,376 @@ static const struct test tests[] = {
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0x1p+0, false, false,
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0x1p+0, false, false,
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0x1.0000000000000000000000000001p+0, false, false),
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TEST ("0x30000002222225p-1077",
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x8p-152, false, true,
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false,
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0x1.800000111111p-1024, false, true,
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0x1.8000001111114p-1024, false, true,
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0x1.800000111111p-1024, false, true,
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0x1.8000001111114p-1024, false, true,
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true,
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0x1.80000011111128p-1024, false, false,
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0x1.80000011111128p-1024, false, false,
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0x1.80000011111128p-1024, false, false,
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0x1.80000011111128p-1024, false, false,
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true,
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0x1.80000011111128p-1024, false, false,
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0x1.80000011111128p-1024, false, false,
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0x1.80000011111128p-1024, false, false,
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0x1.80000011111128p-1024, false, false,
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false,
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0x1.800000111111p-1024, false, true,
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0x1.8000001111114p-1024, false, true,
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0x1.800000111111p-1024, false, true,
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0x1.8000001111114p-1024, false, true,
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true,
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0x1.80000011111128p-1024, false, false,
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0x1.80000011111128p-1024, false, false,
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0x1.80000011111128p-1024, false, false,
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0x1.80000011111128p-1024, false, false),
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TEST ("0x0.7fffffffffffeap-1022",
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x8p-152, false, true,
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false,
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0x1.ffffffffffff8p-1024, false, true,
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0x1.ffffffffffffcp-1024, false, true,
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0x1.ffffffffffff8p-1024, false, true,
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0x1.ffffffffffffcp-1024, false, true,
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true,
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0x1.ffffffffffffa8p-1024, false, false,
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0x1.ffffffffffffa8p-1024, false, false,
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0x1.ffffffffffffa8p-1024, false, false,
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0x1.ffffffffffffa8p-1024, false, false,
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true,
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0x1.ffffffffffffa8p-1024, false, false,
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0x1.ffffffffffffa8p-1024, false, false,
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0x1.ffffffffffffa8p-1024, false, false,
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0x1.ffffffffffffa8p-1024, false, false,
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false,
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0x1.ffffffffffff8p-1024, false, true,
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0x1.ffffffffffffcp-1024, false, true,
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0x1.ffffffffffff8p-1024, false, true,
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0x1.ffffffffffffcp-1024, false, true,
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true,
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0x1.ffffffffffffa8p-1024, false, false,
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0x1.ffffffffffffa8p-1024, false, false,
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0x1.ffffffffffffa8p-1024, false, false,
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0x1.ffffffffffffa8p-1024, false, false),
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TEST ("0x0.7fffffffffffe9p-1022",
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x8p-152, false, true,
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false,
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0x1.ffffffffffff8p-1024, false, true,
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0x1.ffffffffffffcp-1024, false, true,
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0x1.ffffffffffff8p-1024, false, true,
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0x1.ffffffffffffcp-1024, false, true,
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true,
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0x1.ffffffffffffa4p-1024, false, false,
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0x1.ffffffffffffa4p-1024, false, false,
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0x1.ffffffffffffa4p-1024, false, false,
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0x1.ffffffffffffa4p-1024, false, false,
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true,
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0x1.ffffffffffffa4p-1024, false, false,
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0x1.ffffffffffffa4p-1024, false, false,
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0x1.ffffffffffffa4p-1024, false, false,
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0x1.ffffffffffffa4p-1024, false, false,
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false,
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0x1.ffffffffffff8p-1024, false, true,
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0x1.ffffffffffffcp-1024, false, true,
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0x1.ffffffffffff8p-1024, false, true,
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0x1.ffffffffffffcp-1024, false, true,
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true,
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0x1.ffffffffffffa4p-1024, false, false,
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0x1.ffffffffffffa4p-1024, false, false,
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0x1.ffffffffffffa4p-1024, false, false,
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0x1.ffffffffffffa4p-1024, false, false),
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TEST ("0x0.7ffffd4p-126",
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false,
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0x1.fffffp-128, false, true,
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0x1.fffff8p-128, false, true,
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0x1.fffffp-128, false, true,
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0x1.fffff8p-128, false, true,
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true,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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true,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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true,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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true,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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true,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false,
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0x1.fffff5p-128, false, false),
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TEST ("0x0.7ffffffffffffffd4p-16382",
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x8p-152, false, true,
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x4p-1076, false, true,
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false,
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0x1.fffffffffffffffp-16384, false, true,
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0x1.fffffffffffffff8p-16384, false, true,
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0x1.fffffffffffffffp-16384, false, true,
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0x1.fffffffffffffff8p-16384, false, true,
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false,
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0x1.fffffffffffffff4p-16384, false, true,
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0x1.fffffffffffffff4p-16384, false, true,
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0x1.fffffffffffffff4p-16384, false, true,
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0x1.fffffffffffffff8p-16384, false, true,
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x4p-1076, false, true,
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true,
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0x1.fffffffffffffff5p-16384, false, false,
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0x1.fffffffffffffff5p-16384, false, false,
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0x1.fffffffffffffff5p-16384, false, false,
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0x1.fffffffffffffff5p-16384, false, false),
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TEST ("0x0.7ffffffffffffffd4p-16383",
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x8p-152, false, true,
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x4p-1076, false, true,
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false,
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0xf.ffffffffffffff8p-16388, false, true,
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0xf.ffffffffffffff8p-16388, false, true,
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0xf.ffffffffffffff8p-16388, false, true,
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0x1p-16384, false, true,
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false,
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0xf.ffffffffffffff8p-16388, false, true,
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0xf.ffffffffffffffcp-16388, false, true,
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0xf.ffffffffffffff8p-16388, false, true,
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0xf.ffffffffffffffcp-16388, false, true,
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x4p-1076, false, true,
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true,
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0xf.ffffffffffffffa8p-16388, false, false,
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0xf.ffffffffffffffa8p-16388, false, false,
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0xf.ffffffffffffffa8p-16388, false, false,
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0xf.ffffffffffffffa8p-16388, false, false),
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TEST ("0x0.7ffffffffffffffffffffffffffeap-16382",
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x8p-152, false, true,
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x4p-1076, false, true,
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false,
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0x1.fffffffffffffff8p-16384, false, true,
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0x2p-16384, false, true,
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0x1.fffffffffffffff8p-16384, false, true,
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0x2p-16384, false, true,
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false,
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0x1.fffffffffffffffcp-16384, false, true,
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0x2p-16384, false, true,
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0x1.fffffffffffffffcp-16384, false, true,
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0x2p-16384, false, true,
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x4p-1076, false, true,
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false,
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0x1.fffffffffffffffffffffffffff8p-16384, false, true,
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0x1.fffffffffffffffffffffffffffcp-16384, false, true,
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0x1.fffffffffffffffffffffffffff8p-16384, false, true,
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0x1.fffffffffffffffffffffffffffcp-16384, false, true),
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TEST ("0x0.7000004p-126",
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false,
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0x1.cp-128, false, true,
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0x1.cp-128, false, true,
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0x1.cp-128, false, true,
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0x1.c00008p-128, false, true,
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true,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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true,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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true,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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true,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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true,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false,
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0x1.c00001p-128, false, false),
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TEST ("0x0.70000000000002p-1022",
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false,
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0x0p+0, false, true,
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0x0p+0, false, true,
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0x0p+0, false, true,
|
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0x8p-152, false, true,
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false,
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0x1.cp-1024, false, true,
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0x1.cp-1024, false, true,
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0x1.cp-1024, false, true,
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0x1.c000000000004p-1024, false, true,
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true,
|
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0x1.c0000000000008p-1024, false, false,
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0x1.c0000000000008p-1024, false, false,
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0x1.c0000000000008p-1024, false, false,
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0x1.c0000000000008p-1024, false, false,
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true,
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0x1.c0000000000008p-1024, false, false,
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0x1.c0000000000008p-1024, false, false,
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0x1.c0000000000008p-1024, false, false,
|
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0x1.c0000000000008p-1024, false, false,
|
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false,
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0x1.cp-1024, false, true,
|
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0x1.cp-1024, false, true,
|
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0x1.cp-1024, false, true,
|
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0x1.c000000000004p-1024, false, true,
|
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true,
|
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0x1.c0000000000008p-1024, false, false,
|
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0x1.c0000000000008p-1024, false, false,
|
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0x1.c0000000000008p-1024, false, false,
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0x1.c0000000000008p-1024, false, false),
|
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TEST ("0x0.70000000000000004p-16382",
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false,
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0x0p+0, false, true,
|
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0x0p+0, false, true,
|
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0x0p+0, false, true,
|
||||
0x8p-152, false, true,
|
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false,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x4p-1076, false, true,
|
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false,
|
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0x1.cp-16384, false, true,
|
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0x1.cp-16384, false, true,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.c000000000000008p-16384, false, true,
|
||||
false,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.cp-16384, false, true,
|
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0x1.c000000000000004p-16384, false, true,
|
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false,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x4p-1076, false, true,
|
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true,
|
||||
0x1.c000000000000001p-16384, false, false,
|
||||
0x1.c000000000000001p-16384, false, false,
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0x1.c000000000000001p-16384, false, false,
|
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0x1.c000000000000001p-16384, false, false),
|
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TEST ("0x0.70000000000000004p-16383",
|
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false,
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0x0p+0, false, true,
|
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0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x8p-152, false, true,
|
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false,
|
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0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x4p-1076, false, true,
|
||||
false,
|
||||
0xep-16388, false, true,
|
||||
0xep-16388, false, true,
|
||||
0xep-16388, false, true,
|
||||
0xe.000000000000008p-16388, false, true,
|
||||
false,
|
||||
0xep-16388, false, true,
|
||||
0xep-16388, false, true,
|
||||
0xep-16388, false, true,
|
||||
0xe.000000000000004p-16388, false, true,
|
||||
false,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
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0x4p-1076, false, true,
|
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true,
|
||||
0xe.0000000000000008p-16388, false, false,
|
||||
0xe.0000000000000008p-16388, false, false,
|
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0xe.0000000000000008p-16388, false, false,
|
||||
0xe.0000000000000008p-16388, false, false),
|
||||
TEST ("0x0.70000000000000000000000000002p-16382",
|
||||
false,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x8p-152, false, true,
|
||||
false,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x4p-1076, false, true,
|
||||
false,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.c000000000000008p-16384, false, true,
|
||||
false,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.c000000000000004p-16384, false, true,
|
||||
false,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x0p+0, false, true,
|
||||
0x4p-1076, false, true,
|
||||
false,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.cp-16384, false, true,
|
||||
0x1.c000000000000000000000000004p-16384, false, true),
|
||||
};
|
||||
|
||||
Loading…
Reference in New Issue
Block a user