Path: utzoo!utgpu!water!watmath!clyde!gwu
From: gwu@clyde.ATT.COM (George Wu)
Newsgroups: comp.arch
Subject: Re: 16 & 32 bit vs 32 bit only instructions for RISC.
Summary: Compile time insignificant?
Keywords: CRISP optimizing compilers
Message-ID: <22746@clyde.ATT.COM>
Date: 4 Mar 88 22:15:07 GMT
References: <9651@steinmetz.steinmetz.UUCP> <9678@steinmetz.steinmetz.UUCP> <2574@im4u.UUCP> <929@mtund.ATT.COM>
Reply-To: gwu@clyde.UUCP (George Wu)
Organization: AT&T Bell Laboratories, Whippany NJ
Lines: 44

In article <929@mtund.ATT.COM> bfb@mtund.UUCP (Barry Books) writes:
> . . .  However it had a 32 word stack cache which it seems to me is better
>than registers ( or even register windows which at least allow future
>versions to have more registers without recompiling to take advantage ).

> . . . The thing that impressed me the most was it didn't take
>a killer optimizing compiler ( read big, buggy and slow ) to make the
>machine run fast.  It seems for stack based langauges a stack cache is
>much more sensible than having a bunch of registers that the compiler
>has to figure out what to do with. . . .

     Both of these segments are based on the assumption that compilation takes
up a significant amount of time compared with other tasks. And this certainly
seems correct, especially to developers.

     However, I find that hard to believe. Once a program is correctly
compiled, it will be run many more times than it was compiled, and in the
long run, you are better off optimizing the application code, instead of the
compiler.

     Even in a developer's environment, how often is your machine extended
such that code needs to be recompiled? Remember, your compiler had to be
compiled too. I would expect a good optimizing compiler would yield better
overall system performance here too.

     Overall, I'd expect that sacrificing you're compiler's ability to optimize
code in return for a smaller, faster compiler would be a lose.

>
>Barry Books
>mtund!bfb		better is bigger

     Like you said, "better is bigger." :-)


					George J Wu	

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-- 
					George J Wu	

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