tg at gmplib.org
Fri Aug 14 20:01:26 UTC 2015
"Marco Bodrato" <bodrato at mail.dm.unipi.it> writes:
I prefer 'do while', whenever the initial branch can be saved.
That makes sense.
> I agree with saving variables which are simultaneously alive. In this
> code, n and i are not simultaneously alive.
I like symmetry, eg:
h += up[n] * v0 + mpn_mul_1 (rp, up, n, v0);
h += up[n] * v0 + mpn_addmul_1 (rp, up, n, v0);
but you are right, we have to please compilers, not aesthetic ;-)
I recall to have attempted that, but I didn't want to extend the live
range of a critical variable...
Interesting observation, by writing "h += A + B" we suggest to the
compiler that A and B can be computed in any order; when we write "h += A;
h += B;" we warn the compiler: computing A may have effects on computing
I suppose it used to suggest a bad order, while now it suggests a good
eval order. (While the initial separate statements means there was a
"sequence point" in C parlance, the compiler may reorder things as the
call can not modify the local expression's result.)
A better mullo_basecase will improve the overall speed of sqrlo_dc, then
maybe the speed of sqrt...
A truly good mullo_basecase is written in assembly, of course :-)
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