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Re: ridiculous amounts of padding
- To: Zack Weinberg <zack at rabi dot columbia dot edu>
- Subject: Re: ridiculous amounts of padding
- From: Jeffrey A Law <law at hurl dot cygnus dot com>
- Date: Tue, 12 Jan 1999 20:26:32 -0700
- cc: Peter Barada <pbarada at wavemark dot com>, egcs at cygnus dot com
- Reply-To: law at cygnus dot com
In message <199901121950.OAA15108@rabi.phys.columbia.edu>you write:
> Alignment for efficient copying is a win here, but wouldn't 8 byte
> alignment
> suffice (to be able to use aligned 64 bit load/store instructions)? I'm
> pretty certain this is so for x86, not as sure for other platforms.
Depends on the str* mem* implementations available on the target system.
I've worked on some that would do things like 4X unrolled copies through
64bit wide FP regs if the alignments allowed it.
I'm not saying the alignment isn't over-aggressive, just that it's not as
clear cut as you may think.
jeff