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- From: hrubin@pop.stat.purdue.edu (Herman Rubin)
- Subject: Re: How many vector registers are useful?
- Reply-To: hrubin@pop.stat.purdue.edu (Herman Rubin)
- Organization: Purdue University Statistics Department
- Date: Thu, 28 Jan 1993 13:35:00 GMT
- Approved: compilers@iecc.cambridge.ma.us
- Message-ID: <93-01-210@comp.compilers>
- References: <93-01-174@comp.compilers> <93-01-195@comp.compilers>
- Keywords: architecture, vector
- Sender: compilers-sender@iecc.cambridge.ma.us
- Lines: 30
-
- kirchner@uklira.informatik.uni-kl.de (Reinhard Kirchner) writes:
- > A register has an optimizing effect only when the value in it can be used
- > several times, ...
-
- jlg@cochiti.lanl.gov (J. Giles) writes:
- >[Another effect] (also true of scalars) is when the value is
- >an intermediate.
-
- Suppose one considers a not too outlandish problem, namely, that of
- producing a vector of non-uniform random variables (exponential, normal,
- gamma, beta, etc.). It is possible to vectorize the reasonably efficient
- acceptance-rejection and acceptance-replacement methods available, at
- least if there is a reasonable use of control vectors, and a typical such
- procedure will use about a half-dozen registers. Many of these procedures
- need division, and if division has to be stepped, it will add another
- register or so.
-
- If only one vector process can be done at a time, so far so good. But
- many vector machines can parallelize the vector processes, so we have a
- cause for proliferation. Even if only load and store can be parallelized
- with vector computation, we can add a few more. So it would not surprise
- me if a few dozen would not be a good idea.
- --
- Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
- Phone: (317)494-6054
- hrubin@snap.stat.purdue.edu (Internet, bitnet)
- {purdue,pur-ee}!snap.stat!hrubin(UUCP)
- --
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