https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106831
--- Comment #12 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- The difference with __ibm128 is that in that case there is no semantic significance to whether the low part is +0 or -0, or what the low part is at all when the high part is a NaN. At the C level, such __ibm128 representations should be considered different representations of the same value, not different values. Whereas different DFP quantum exponents for the same real number correspond to different values that compare equal. (Noncanonical DFP encodings might be more closely analogous to the __ibm128 variants, except that most operations aren't supposed to return a noncanonical encoding even if inputs have such an encoding.)
