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Re: [Emacs-diffs] master 605f901: Prefer memcpy and memset to doing it b


From: Paul Eggert
Subject: Re: [Emacs-diffs] master 605f901: Prefer memcpy and memset to doing it by hand
Date: Sun, 7 Feb 2016 13:24:28 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1

John Wiegley wrote:
Is this so performance critical that we can't just always use the memset?

We can't always use the memset. The memset works only if the bit pattern we're trying to store can be implemented by storing the same unsigned char value repeatedly. The important special case here is storing Qnil, which is represented by the all-zeros bit pattern.




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