b59ad2db99
Floating-point classification macros are supposed to remove any excess range or precision from their arguments. This patch fixes the non-sNaN version of iszero to do so, by casting the argument to its own type. (This will of course work only for standard-conforming excess precision, not for what GCC does on 32-bit x86 by default where the back end hides excess precision from the front end; the same applies to most of the classification macros in that case, as showed up when we made them use GCC built-in functions.) (iseqsig will have the reverse issue, needing to ensure that when an underlying function is used it's for a type wide enough not to remove any excess precision, since comparison macros must not remove excess precision.) Tested for x86_64 and x86. * math/math.h [__GLIBC_USE (IEC_60559_BFP_EXT) && !__SUPPORT_SNAN__] (iszero): Cast argument to its own type. * math/test-iszero-excess-precision.c: New file. * math/Makefile (tests): Add test-iszero-excess-precision. (CFLAGS-test-iszero-excess-precision.c): New variable.
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