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Re: Why does gcc produce an unnecessary `nop' instruction?
- From: John Love-Jensen <eljay at adobe dot com>
- To: PRC <panruochen at gmail dot com>
- Cc: MSX to GCC <gcc-help at gcc dot gnu dot org>
- Date: Fri, 25 Jan 2008 06:25:46 -0600
- Subject: Re: Why does gcc produce an unnecessary `nop' instruction?
Hi PRC,
> Is there a particular good reason for 8-byte alignment, even if the target
ARCH is 32-bit rather than 64-bit and aligment is quite a little waste of
storage and runtime memory?
Perhaps your platform supports 64-bit floating point, and that entails
alignment requirements?
Sometimes the "requirements" are performance related (e.g. Intel), sometimes
they avoid SIGBUS but can be "faked" with a sigtrap to handle misalignment
(such as what could be done on the DEC Alpha), sometimes they are really
hard requirements such as MMX/SSE or AltiVec.
Hard to say without looking at the config file for your particular platform.
Sincerely,
--Eljay