The ldbl-96 implementation of scalblnl (used for x86_64 and ia64) uses a condition k <= -63 to determine when a standard underflowing result tiny*__copysignl(tiny,x) should be returned. However, that condition corresponds to values with exponent -16446 or less, and in the case of -16446, the correct result for round-to-nearest depends on whether the value is exactly 0x1p-16446 (half the least subnormal) or more than that. This patch fixes the bug by changing the condition to k <= -64 and accordingly adjusting the exponent by 64 not 63 when converting to a normal value. Tested for x86_64. [BZ #17803] * sysdeps/ieee754/ldbl-96/s_scalblnl.c (twom63): Rename to twom64. Adjust value to 0x1p-64L. (__scalblnl): Only return standard underflowing result for K <= -64 not K <= -63; adjust exponent for underflowing result by 64 not 63. * math/libm-test.inc (scalbn_test_data): Add more tests. (scalbln_test_data): Likewise. |
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.. | ||
bits | ||
dbl-64 | ||
flt-32 | ||
ldbl-64-128 | ||
ldbl-96 | ||
ldbl-128 | ||
ldbl-128ibm | ||
ldbl-opt | ||
Makefile | ||
ieee754.h | ||
k_standard.c | ||
k_standardf.c | ||
k_standardl.c | ||
s_lib_version.c | ||
s_matherr.c | ||
s_signgam.c | ||
support.c |