On Mon, 17 Feb 2014 07:49:18 -0500, Peter Relson wrote:
>
>If the "branch technique" is faster, and depending on how high a
>percentage "most of the time" (as in "most of the time CURRENT will be
>zero") is, then the branch technique given as the alternative to no-branch
>is likely not optimal. Even with branch prediction technology, it is still
>better to have the "expected path" not take a branch.
>
>So, for example (when LT is available),
>
(It's possible that CURRENT has just been calculated and CC is
already set.)
> LT Rx,CURRENT
> JNZ Need_To_Add
>Return_From_Need_To_Add DS 0H
>...
>Need_To_Add DS 0H
> A Rx,SUM
> ST Rx,SUM
> J Return_From_Need_To_Add
>
Is there a maxim here? When the programmer expects that a branch
will usually be taken, is it better to avoid:
BC C,USUALLY
and code instad:
BC 15-C,*+8
B USUALLY
???
>Then you get to factor in how much "readability" is worth to you.
>
Macros are your friend. But does providing "readability" at the
programming interface level make such a macro unpleasantly
verbose internally?
-- gil
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