[Oberon] Constant folding, Re: Bit-fiddling: SETs and type casts in Oberon-07

[Paul Reed]

Hi Jörg,

> ... CHR( ORD(ch) - ORD(“a”) + ORD(“A”) );
> 
> ...the compiler folds these constants into one value

Should perhaps, but doesn't (the Oberon-07 compilers anyway): there is 
some associative and even commutative constant folding which could be 
done, but isn't currently. RISC ORTool gives:

PROCEDURE P;
   VAR ch: CHAR;
BEGIN ch := CHR( ORD(ch) - ORD("a") + ORD("A") );
END P;

    2  90E00004 LDR  R0 SP       4
    3  40090061 SUB  R0  R0     97
    4  40080041 ADD  R0  R0     65
    5  B0E00004 STR   R0 SP       4

Cheers,
Paul