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Re: bootstrap problem with union Lisp_Object

From: Stefan Monnier
Subject: Re: bootstrap problem with union Lisp_Object
Date: Tue, 06 Dec 2005 17:26:37 -0500
User-agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.50 (gnu/linux)

>     Fixed...  With these options enabled, EQ evaluates its arguments
>     twice.  A while back, Stefan changed NILP to use EQ instead of
>     XFASTINT, which is cleaner, but it turns out some invocations of NILP
>     had non-idempotent arguments.
> Why doesn't EQ use XFASTINT?  We want it to be as fast as possible.

XFASTINT is "slow" (identical to XINT, in the now default case of
USE_LSB_TAG) and incorrect (it fails to check that the tag bits are equal).

If Lisp_Object=int (or long), we want to use "=" directly, which is exactly
what happens with `EQ'.


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