On Thu, Jul 1, 2021 at 3:10 PM Joseph Myers <jos...@codesourcery.com> wrote: > > On Thu, 1 Jul 2021, H.J. Lu via Gcc-patches wrote: > > > 2. Return _Float16 and _Complex _Float16 values in %xmm0/%xmm1 registers. > > That restricts use of _Float16 to processors with SSE. Is that what we > want in the ABI, or should _Float16 be available with base 32-bit x86 > architecture features only, much like _Float128 and the decimal FP types
Yes, _Float16 requires XMM registers. > are? (If it is restricted to SSE, we can of course ensure relevant libgcc > functions are built with SSE enabled, and likewise in glibc if that gains > _Float16 functions, though maybe with some extra complications to get > relevant testcases to run whenever possible.) > _Float16 functions in libgcc should be compiled with SSE enabled. BTW, _Float16 software emulation may require more than just SSE since we need to do _Float16 load and store with XMM registers. There is no 16bit load/store for XMM registers without AVX512FP16. -- H.J.
