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Matt Turner
548997eb13
The reference implementation renders the a and A conversions by splitting the value into a significand of the width the type has and a power of two. That presumes the type is a single binary floating-point format. The IBM extended format is a pair of doubles instead, whose combined significand has no fixed width and whose subnormals are those of the low double rather than of the type, so what glibc produces for it does not follow from PREC and MINEXP: LDBL_MAX comes out as 0x1.fffffffffffff7ffffffffffff8p+1023 with twenty-eight fractional digits where the value has at most twenty-six worth of significand, and LDBL_TRUE_MIN as 0x0.0000000000001p-1022, which is the smallest subnormal double and nowhere near LDBL_MIN_EXP. The remaining conversions are unaffected, as they work from the value rather than from a decomposition of it, and were verified to be. Add an UNSUPPORTED_CONVS definition to the skeleton for conversions that cannot be modeled for the type at hand, and set it to the a and A pair where long double has that format, the generator then producing no records and an unsupported status which the long double wrapper reports. Tested on x86_64-linux-gnu and powerpc64le-linux-gnu, where all 672 results pass, and with the long double conversions forced to the IBM extended format, where the a and A ones report unsupported and the rest continue to pass. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>