Related articles |
---|
Re: loops preston@dawn.cs.rice.edu (1992-02-25) |
Re: loops mwolfe@ogicse.ogi.edu (1992-02-26) |
Re: loops wall@pa.dec.com (1992-02-26) |
Re: loops clc5q@hemlock.cs.Virginia.EDU (1992-02-28) |
Newsgroups: | comp.compilers |
From: | wall@pa.dec.com (David Wall) |
Keywords: | optimize |
Organization: | DEC Palo Alto |
References: | <9202220021.AA28153@ucbvax.Berkeley.EDU> 92-02-113 |
Date: | Wed, 26 Feb 92 21:11:25 GMT |
Preston Briggs asks whether we should treat
do {
do {
<A>
} while ()
} while ()
as one loop or a nested pair.
Though intuition suggests that it is a pair, there is at least one
reason to treat it as one loop. Something like
while () {
switch () {
case foo:
...; break;
case bar:
...; break;
case baz:
...; break;
}
is otherwise very easy to mislabel as a triply-nested loop, if we
have already optimized the breaks into jumps back to the header.
When you run into a 100-ply switch statement that your compiler
calls a 100-deep nested loop, it really sticks with you, believe
me. Your hair -never- grows back.
David W. Wall - - - - - - - - - - - - - - - - wall@decwrl.dec.com
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