🚀 go-pugleaf

In article <70755@ti-csl.csc.ti.com> holland@m2.UUCP (Fred Hollander) writes:
>In article <41a2364a.a590@mag.engin.umich.edu> billkatt@caen.engin.umich.edu (billkatt) writes:
>>is in an object oriented format.  Yes, it is doubtful that they will do a
>>rewrite in Pascal, since the system is currently written in Assembly
>>language, and RISC chips are optimized for C.
>
>This is very interesting.  I don't have the strongest background in
>hardware architecture, but, could you please explain how a processor
>could be optimized for a specific high level language?

Well, the statement isn't entirely true.  There exist RISC chips that
are optimized for C, but RISC doesn't imply C optimization.  The MIPS
chip, for example, is more optimized for Unix in general than C.  After
all, you don't need virtual memory just for C, and the R[23]000 have a
TLB just for that reason.

Anyway, to answer the question, RISC means "reduced instruction set
computer", and also tends to imply a reduced number of addressing
modes as well.  Since you are limited in instructions and addressing modes,
you need to pick those which are beneficial to your application.
Since C compilers don't have a "string" primitive, it is unlikely
that a C compiler would be able to use string instructions, so you
might leave these out.  You can also examine a large set of "typical"
programs and see how many registers you are likely to need.

The architects and designers take this information and use it to
efficiently utilize the chip area.  In the MIPS architecture, the
goal was to keep the pipeline from stalling, so instructions
were implemented so that they could be executed in a single cycle
(note: this doesn't mean that instructions take only one cycle
to execute).  Also, the extra chip area was used to make the multiplier
faster and to implement TLB registers for virtual memory.

In other words, you optimize for the final application by putting
together a group of experts.  In the case of a Unix processor, you
get C compiler and Unix kernel experts.  If you were working on an
imbedded controller chip, you would get people who understand devices
and device drivers.

-- 
David Elliott		...!pyramid!boulder!stan!dce
"Splish splash, I was rakin' in the cash"  -- Eno