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From: David Chisnall <theraven@FreeBSD.org>
In-Reply-To: <20120511124820.GN2358@deviant.kiev.zoral.com.ua>
Date: Fri, 11 May 2012 08:57:29 -0400
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References: <201205111237.q4BCbGX2083596@svn.freebsd.org>
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To: Konstantin Belousov <kostikbel@gmail.com>
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Cc: svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org,
	src-committers@FreeBSD.org, Gabor Kovesdan <gabor@FreeBSD.org>
Subject: Re: svn commit: r235267 - in head/usr.bin/sort: . nls
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On 11 May 2012, at 08:48, Konstantin Belousov wrote:

> On Fri, May 11, 2012 at 12:37:16PM +0000, Gabor Kovesdan wrote:
>> Author: gabor
>> Date: Fri May 11 12:37:16 2012
>> New Revision: 235267
>> URL: http://svn.freebsd.org/changeset/base/235267
>=20
>> +bool byte_sort =3D false;
>> +
>> +static wchar_t **wmonths =3D NULL;
>> +static unsigned char **cmonths =3D NULL;
>=20
> Such initializations are useless. You only increase the size of the =
binary
> on the disk as the consequence.

Really?  The C specification requires all globals and statics that are =
not explicitly initialised to be set to their zero value, so this =
initialisation has no effect on the resulting binary[1].  These are =
placed in the BSS section, irrespective of whether the initialisation is =
implicit or explicit and the loader is responsible for allocating space =
for them - all that is stored in the binary is the size.

For local variables, initialisation like this has no effect even at low =
optimisation levels - dead stores will be removed.  It does, however, =
make it more difficult for the compiler to distinguish between =
initialised and initialised sensibly in some cases.

David

[1] In a standards-compliant compiler.  Apparently a few shipping =
compilers for embedded systems fail to respect this, but everything =
FreeBSD is compiled with does.=