On 05/22/2018 07:50 AM, Peter Maydell wrote: > Hi; I was reading about the x86-64 calling convention and I found > out that apparently for returns of smaller-than-register types the > high parts may contain garbage: > https://stackoverflow.com/questions/36706721/is-a-sign-or-zero-extension-required-when-adding-a-32bit-offset-to-a-pointer-for/36760539#36760539
Yes, that's one reason I didn't want to get involved in returning a "real" 16-bit quantity. > However, for TCG helper functions, although we allow the helper > macro to say that the return type is 'f16', in helper-head.h we > seem to just alias f16 as i32, and in dh_sizemask() we only record > "is this 64 bits" and "is this signed". Am I missing the place > where we zero-extend the value we get back from the helper so > that it's the right thing in TCG's i32 ? It happens in C, implicit in "typedef uint16_t float16". r~
