*BSD News Article 55040


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From: hiroshi@teine.chem2.hokudai.ac.jp (Hiroshi Murakami)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: gcc: strong request for 8 byte alignment for double.
Date: 10 Nov 1995 14:35:52 GMT
Organization: Hokkaido Univ., Sapporo, Japan.
Lines: 11
Message-ID: <47vo08$t62@nyx.eos.hokudai.ac.jp>
NNTP-Posting-Host: teine.chem2.hokudai.ac.jp


We found, that gcc-2.6.3 comes with FreeBSD2.1 pre-release
does not honor the 8 byte alignment for double variables.
On Pentium, which has 64bits bus, if the double alignment
were not made, every load/store, fp arithmetics slows down
in factor of about two. The users programs without any sign
could be slow by this reason unless the address of variables
or arrays are examined.

Please let the compiler/linker/loader to honor this alignment,
otherwise the performance is just wasted.