On 3/19/20 8:47 AM, Wilco Dijkstra wrote:
> Hi Richard,
>
> Thanks for these patches - yes TI mode expansions can certainly be improved!
> So looking at your expansions for signed compares, why not copy the optimal
> sequence from 32-bit Arm?
>
> Any compare can be done in at most 2 instructions:
>
> void doit(void);
> void f(long long a)
> {
> if (a <= 1)
> doit();
> }
>
> f:
> cmp r0, #2
> sbcs r3, r1, #0
> blt .L4
Well, this one requires that you be able to add 1 to an input and for that
input to not overflow. But you're right that I should be using this sequence
for LT (not LE).
I'll have another look.
r~
