On Tuesday, 23 May 2017 at 13:27:42 UTC, Andrei Alexandrescu
wrote:
On 5/22/17 4:51 PM, Johan Engelen wrote:
On Monday, 22 May 2017 at 15:05:24 UTC, Andrei Alexandrescu
wrote:
[...]
A fun read!
"(Late at night, I double checked. Mozilla’s CheckedInt is
just as bad as I remembered. They do a division to test for
multiplication overflow. Come on, put a line of assembler in
there! Portability is worth a price, just not any price.)"
Shocked: do you use assembly in Checked and cripple the
optimizer?!?!
Luckily, no. But LDC and GDC do create the `seto` instruction
I think you were hinting at:
https://godbolt.org/g/0jUhgs
(LDC doesn't do as good as it could,
https://github.com/ldc-developers/ldc/issues/2131)
Thanks! Yes, seto is what I thought of - one way or another, it
gets down to using a bit of machine-specific code to get there.
I'll note that dmd does not generate seto (why?):
https://goo.gl/nRjNMy. -- Andrei
it does this
overflow_flag = 0
op
if (overflowed)
{
overflow_flag = 1;
}
this can in some circumstances be faster then using seto!
If the inliner does a good enough job :)
