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From: "Russ Cox" <rsc@swtch.com>
To: "Fans of the OS Plan 9 from Bell Labs" <9fans@cse.psu.edu>
Subject: Re: [9fans] Include guards and multiple includes
Date: Fri, 20 Oct 2006 16:18:52 -0400	[thread overview]
Message-ID: <ee9e417a0610201318o469eeec9lacd7c7ed2924fcc1@mail.gmail.com> (raw)
In-Reply-To: <7871fcf50610201227s17987c4at9bafba8729f8a6b9@mail.gmail.com>

There was a time when there was an efficiency argument
to be made (don't have to read and parse the files over and over),
but gcc did an end run around it by recognizing files with
the traditional #ifndef #define #endif sequence and
then not even re-opening the file the next time it gets
included.

Arguably gcc didn't even have to do this, though: the rest
of the compiler is so slow that parsing the headers multiple
times is hardly the performance bottleneck.

Russ


  reply	other threads:[~2006-10-20 20:18 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-10-20 18:45 Paul Lalonde
2006-10-20 19:27 ` Joel Salomon
2006-10-20 20:18   ` Russ Cox [this message]
2006-10-20 20:37     ` Paul Lalonde
2006-10-22 16:37       ` Joel Salomon
2006-10-23 12:29         ` Charles Forsyth
2006-10-20 23:15 ` geoff
2006-10-20 23:39   ` Bruce Ellis
2006-10-24 14:32   ` AtomicKobold Design
2006-10-23 12:39 ` Rogelio Serrano
2006-10-23 12:41   ` erik quanstrom
2006-10-23 12:52     ` Rogelio Serrano
2006-10-23 13:26       ` erik quanstrom
2006-10-23 15:30         ` Joel Salomon
2006-10-23 18:43         ` Charles Forsyth
2006-10-23 19:12           ` Joel Salomon
2006-10-23 20:23             ` geoff

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