Hi Segher and Peter On 21/11/2018 17.52, Peter Bergner wrote: > On 11/21/18 7:13 AM, Segher Boessenkool wrote: >> There is no such switch. Implementing such a switch would be hard; for >> example, the convert-float-to-integer instructions need to store an integer >> in a floating point register. Thanks for the answer. I accept that it would be hard to do such a switch, though I don't think I understand that example. Why would gcc ever create an int-to-float or float-to-int unless the source code actually used float or double? >> Compiling translation units with different needs, with different flags, is >> the way to go. -msoft-float means "do not use the FPRs". > > I agree with Segher here. I'll note though that -msoft-float and -mhard-float > are different ABIs. However, if you don't call a function across the soft-float > to hard-float barrier that has floating point arguments or floating point > return value, you should be fine. We may have to do it that way, then. But I would hope to have some help from the compiler to detect ABI violations, or generation of soft-float code. We could build everything with -msoft-float, and all such code should be forbidden from using float/double/long double in any way - calling functions taking those, defining variables, casting to/from, ... either via a new warning, or a hypothetical '-mno-float' [which I see actually exists for MIPS]. Then we could selectively turn on -mhard-float for the few TUs that actually need that. Thanks, Rasmus
