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Re: [Emacs-diffs] trunk r117007: Optimize cl-struct-slot-value; fix test

From: Daniel Colascione
Subject: Re: [Emacs-diffs] trunk r117007: Optimize cl-struct-slot-value; fix test
Date: Mon, 21 Apr 2014 21:35:33 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0

On 04/21/2014 09:34 PM, Stefan Monnier wrote:
>> -  (elt inst (cl-struct-slot-offset struct-type slot-name)))
>> +  ;; We could use `elt', but since the byte compiler will resolve the
>> +  ;; branch below at compile time, it's more efficient to use the
>> +  ;; type-specific accessor.
>> +  (if (eq (cl-struct-sequence-type struct-type) 'vector)
>> +      (aref inst (cl-struct-slot-offset struct-type slot-name))
>> +    (nth (cl-struct-slot-offset struct-type slot-name) inst)))
> It won't always resolve the (eq (cl-struct-sequence-type struct-type)
> 'vector) test at compile-time, tho.

It did in my tests, when struct-type was a symbol. When struct-type is
something that might vary, the branch shows up in the bytecode. Maybe
the comment should say "will resolve...when possible".

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