[Oberon] Numeric CASE vs IF THEN ELSE Performance
Andreas Pirklbauer
andreas_pirklbauer at yahoo.com
Fri Jun 29 19:54:47 CEST 2018
> The standard branch via register instruction is
>
> BR,cond [Rn]
>
> The new variant of this instruction is
>
> BR,cond PC,[Rn]
>
> i.e. the target of the branch is computed by adding the
> contents of register n to the current program counter.
>
> Consequently, the average overhead of any selection
> in a CASE statement, including range checking,
> is now a constant 6 instructions.
Just for the record: With the original “standard” branch via
register instruction BR,cond [Rn], as currently defined in
RISC, that number is a constant 8 instructions.
so.. it’s 8 vs 6
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