Talking to a rock.

[Alan Bawden <ALAN at MIT-MC>]

    Date: 18 SEP 1980 1618-EDT
    From: JONL at MIT-MC (Jon L White)

        Date: 18 September 1980 16:02-EDT
        From: Alan Bawden <ALAN at MIT-MC>
        Subject: (LDB 0203 Y) versus (LDB X Y)
        .  .  .
        (ldb 0203 y) expands into (boole 1 (lsh y -2) 7)
        (ldb x y)    expands into (*ldb (lsh x 30) y)
        I don't see anything that looks like (*ldb ppss_30 ...) 
        so I don't see
        how anything has been saved.
    Are you asleep today!  How do you think the "7" got generated in the line
        "(ldb 0203 y) expands into (boole 1 (lsh y -2) 7)"
What difference does it make where the 7 comes from??
    *LDB is not a user-available function -- it exists only as a stop-gap
    until the compiler open-codes LDB.  (Although it is true now that *LDB is 
    never handed a "constant" arg, that's not how it was when *LDB was first 
    coded -- the conversion to BOOLE is a recent innovation -- but the whole 
    existence of *LDB depends on whether or not the compiler knows how to 
    open-code LDB).  Anyway, why are you worrying about this -- is it slowing 
    your program down by 0.25%?
I don't have to worry about it.  I LAPed up a LDB and a DPB of my own
a long time ago and I still don't have any reason to flush them.
What I am amazed by is the totally hairy "stop gap" measures that
don't gain anything!