Re: [opensuse] Assembly Language program

On Sun, 03 Jun 2007 11:03:34 +0100
G T Smith <grahamsmith@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Some assembler code is truly ugly (using 100s of NOPS for timing is one
example I can think off), where timing or speed is essential one will
nearly always get a better result with well written assembler (it often
is not pretty to look at at)..

Just a general comment on this since I was one of the authors of the
Unix/Windows NT assembler for the Alpha chip. (This is a bit of a
generalization) Alpha chip could execute multiple simultaneous streams
(2 or 4 depending on the chip version), but the instructions had to be
ordered properly for this to happen. We used a "scheduler" as an
optimization as the last pass of the assembler. In some cases, using
NOPs had a positive performance effect. Additionally, in the Intel
Itanium chip, they pack 6 instructions together, and properly placed
NOPs help performance.

--
Jerry Feldman <gaf@xxxxxxx>
Boston Linux and Unix user group
http://www.blu.org PGP key id:C5061EA9
PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9

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