On 10/21/20 10:46 AM, Alex Bennée wrote: >> This layout, with the big-endian ordering, means that storage >> can be shared between them, just by ignoring the least significant >> words of the fraction as needed. Which may make muladd more >> understandable. > > Would the big-endian formatting hamper the compiler on x86 where it can > do extra wide operations?
Well, you couldn't just use Int128 in the structure. But you could write the helpers via int128_make128/getlo/gethi, which would still get the compiler expansion. >> However, the big-endian word ordering means that Int128 >> cannot be used directly; so a set of wrappers are needed. >> If added the Int128 routine just for use here, then it's >> probably easier to bypass Int128 and just code it here. > > Are you talking about all our operations? Will we still need to#ifdef > CONFIG_INT128 in the softfloat code? If we decline to put the operation into qemu/int128.h, because they're not generally useful, then yes, we may put those ifdefs into our softfloat code. r~
