On 07-01-2012 00:37, Jonathan M Davis wrote:
On Saturday, January 07, 2012 00:03:39 Alex Rønne Petersen wrote:
Most likely those functions are just implemented using inline assembly,
therefore not usable in CTFE.
Yeah, several functions in std.math use inline assembly. So, for them to be
able to be used at compile time, either the compiler must be expanded to be
able to run asm statements at compile time (which may or may not be planned
and may or may not be reasonable), or those functions need another branch
(using __cfte in an if condition) which doesn't use assembly. Or I suppose
that if the extra check for __ctfe isn't considered particularly acceptable
(after all, they're already using assembly), then separate functions meant
specifically for CTFE would be necessary. I don't know what Don's preferred
approach would be, but presumably, it would be up to him since he's the
primary maintainer of both CTFE and std.math.
An enhancement request for it should probably be opened: d.puremagi.com/issues
- Jonathan M Davis
Allowing asm in CTFE would probably be way more work than it's worth.
You'd basically need full-blown analysis of x86 assembly plus an
interpreter. Even then, x86 is not typed, so it's going to be a major
pain...
--
- Alex
