Re: Optimization tradeoffs (time vs. space)

roy@phri.uucp (Roy Smith)
10 Aug 88 14:00:19 GMT

          From comp.compilers

Related articles
Optimization tradeoffs (time vs. space) roy@phri.uucp (1988-08-01)
Re: Optimization tradeoffs (time vs. space) markhall@pyramid.pyramid.com (1988-08-05)
Re: Optimization tradeoffs (time vs. space) ames!coherent!dplatt@ncar.UCAR.EDU (1988-08-05)
Re: Optimization tradeoffs (time vs. space) tekcrl.tek.com!willc@RELAY.CS.NET (Will Clinger) (1988-08-06)
Re: Optimization tradeoffs (time vs. space) gbs@nsc.nsc.com (1988-08-08)
Optimization tradeoffs (time vs. space) midkiff@uicsrd.csrd.uiuc.edu (1988-08-09)
Re: Optimization tradeoffs (time vs. space) roy@phri.uucp (1988-08-10)
Re: Optimization tradeoffs (time vs. space) mmengel@cuuxb.ATT.COM (1988-08-11)
| List of all articles for this month |

From: roy@phri.uucp (Roy Smith)
Newsgroups: comp.compilers
Date: 10 Aug 88 14:00:19 GMT
References: <1989@ima.ISC.COM>
Organization: Public Health Research Inst. (NY, NY)

midkiff@uicsrd.csrd.uiuc.edu (Sam Midkiff) writes:
> One dramatic space/time tradeoff occurs in vectorizing and parallelizing
> compilers. The transformation is called "scalar expansion". For example,
> consider the loop:
>
> do i = 1, n
> a = b + c
> d = a + e
> end


I'm confused. Since b, c, and e are all constants (invariant
inside the loop), can't you just re-write this as


a = b + c
d = a + e


without the loop at all? Unless, of course, you meant to write "a(i)"
instead of "a", etc, which I would guess is what you meant (and is
certainly the example given in the CACM paper you mentioned).
--
Roy Smith, System Administrator
Public Health Research Institute
{allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net
"The connector is the network"
[Mea culpa for not asking him to clarify it --John]
--


Post a followup to this message

Return to the comp.compilers page.
Search the comp.compilers archives again.