On Thu, Jan 22, 2015 at 4:35 AM, H.J. Lu <hjl.to...@gmail.com> wrote: > Here is the link: > > https://groups.google.com/forum/#!topic/ia32-abi/nq6cvH_VVV4
The document contains this claim (as do many other psABI documents): "Bit-fields that are neither signed nor unsigned always have non-negative values. Although they may have type char, short, int, or long (which can have negative values), these bit-fields have the same range as a bit-field of the same size with the corresponding unsigned type." This does not reflect the ABI as widely implemented, and is incompatible with C++ (in which plain bit-fields are required to be signed). GCC documents why they ignore the psABI in this regard here: https://gcc.gnu.org/onlinedocs/gcc/Non-bugs.html#Non-bugs I would suggest either removing this specification from the psABI or correcting it to reflect actual implementation practice: plain bit-fields are signed.
