Tue, 9 Aug 88 09:34:13 CDT

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) |

Date: | Tue, 9 Aug 88 09:34:13 CDT |

From: | midkiff@uicsrd.csrd.uiuc.edu (Sam Midkiff) |

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

The loop cannot be run in parallel as written, since the value of

"a" used in the second statement will be indeterminate, as will the

final value of "d". If, however, the loop is transformed to:

do i = 1, n

a'(i) = b + c

d'(i) = a'(i) + e

end

d = d'(n)

a = a`(n)

it can be run in parallel. A more complete discussion of this, and other

optimizing transformations, can be found in:

%A D. Padua

%A M. Wolfe

%T Advanced Compiler Optimization for Supercomputers

%J CACM

%V 29

%N 12

%P 1184-1201

%D December, 1986

[From midkiff@uicsrd.csrd.uiuc.edu (Sam Midkiff)]

--

Post a followup to this message

Return to the
comp.compilers page.

Search the
comp.compilers archives again.