Re: Effect of pointers etc.

preston@dawn.cs.rice.edu (Preston Briggs)
Sat, 27 Mar 1993 17:27:36 GMT

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Related articles
Effect of pointers etc. sharma@math.tu-berlin.de (1993-03-26)
Re: Effect of pointers etc. preston@dawn.cs.rice.edu (1993-03-27)
Re: Effect of pointers etc. paco@legia.cs.rice.edu (1993-03-28)
Effect of pointers etc. ssimmons@convex.com (1993-03-29)
Re: Effect of pointers etc. firth@sei.cmu.edu (1993-03-30)
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Newsgroups: comp.compilers,comp.parallel
From: preston@dawn.cs.rice.edu (Preston Briggs)
Keywords: parallel, analysis
Organization: Rice University, Houston
References: 93-03-105
Date: Sat, 27 Mar 1993 17:27:36 GMT

sharma@math.tu-berlin.de (Sharma) writes:
>My job is to say how many operations are required.


>The algorithms contain lots of 2 dimensional arrays (naturally). Now what
>is the cost in terms of hardware of macros such as these
>
>#define DISP1(i,j) *(dispar.disp0 + i*MAX_X0 + j)
>#define DISP(i,j) *(dispar.displr + i*MAX_X0 + j)
>#define DISPold(i,j) *(dispar.disp_old + i*MAX_X0 + j)


Hard to say from fragments. Depends on whether the values of i, MAX_X0,
and j can be detemrined at compile-time.


An approach might be to compile the mess and run it with some sort of nice
measurement tool, say a variant of pixie. It'll tell you how many
operations are actually executed for the particular run. You'll have to
design your experiments carefully, but it all sounds much more doable than
trying to interpret grotty C.


Preston Briggs
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