## pardo@cs.washington.edu (David Keppel)Tue, 7 Dec 1993 18:59:22 GMT

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 Newsgroups: comp.compilers From: pardo@cs.washington.edu (David Keppel) Keywords: optimize, report, FTP Organization: Computer Science & Engineering, U. of Washington, Seattle Date: Tue, 7 Dec 1993 18:59:22 GMT

We (Keppel, Eggers and Henry) have a new TR about the use of Runtime Code
Generation (RTCG) for performing optimizations based on the values of
particular variables. I think I forgot to post a blurb about it, so
here's the abstract:

Traditional compiler optimizations are either data-independent or optimize
around common data values while retaining correct behavior for uncommon
values. This paper examines {\em value-specific} data-dependent
optimizations (VSO), where code is optimized at runtime around particular
input values. Because VSO optimizes for the specific case, the resulting
code is more efficient. However, since optimization is performed at
runtime, the performance improvement must more than pay for the runtime
compile costs. We describe two VSO implementation techniques and compare
the performance of applications that have been implemented using both VSO
and static code. The results demonstrate that VSO produces better code
and often for reasonable input sizes. The machine-independent
implementations showed speedups of up to 1.5 over static C code, and the
machine-dependent versions showed speedups of up to 4.3 over static
assembly code.

The paper is UWCSE TR #93-11-02 and is available via anonymous ftp from
ftp.cs.washington.edu' in the tr' subdirectory; login anonymous, use
so be sure to do the transfer in binary mode. If you can't ftp it for
some reason send me e-mail and I can e-mail you a copy or find out about
how to request a paper copy. And for you bibliography hounds:

%A David Keppel
%A Susan J. Eggers
%A Robert R. Henry
%T Evaluating Runtime-Compiled Value-Specific Optimizations
%R 93-11-02
%I University of Washington Department of Computer Science and
Engineering
%D November 1993
%W pardo@cs.washington.edu

;-D on ( "Tech Talk", with hosts Boot and Resume ) Pardo
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