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From: Simon Wright <simon.j.wright@mac.com>
Newsgroups: comp.lang.ada
Subject: Re: Reading and writing a big file in Ada (GNAT) on Windows XP
Date: Sun, 29 Apr 2007 08:20:44 +0100
Organization: Pushface
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Date: 2007-04-29T08:20:44+01:00
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Jeffrey Creem <jeff@thecreems.com> writes:

> Simon Wright wrote:
>> Fionn Mac Cumhaill <invisible@hiding.from.spam> writes:
>>
>>> The modifications consist of replacing a slice of text at the end of
>>> a line with another bit of text. The biggest slice is 10 characters,
>>> and the replacement slice is always smaller than the original
>>> slice. An occasional line of text is about 6000 characters long, but
>>> most are about 700 haracters.  Get_Line reads them into a String
>>> variable that is 10,000 characters long.
>>
>> Yesterday I found a performance (and stack!) related problem in GNAT's
>> Ada.Strings.Fixed.Index. The string is mapped onto the stack before
>> the search is done. But I wouldn't have thought this would result in a
>> 5 hour run time. How do you decide which lines need conversion?
>
> I agree, it does not seem that either that or the guesses I had
> related to zeroing at the string (a common mistake) would result in
> the level of slowdown being seen...However, now that you mention it, I
> see a few ugly things like that related to Ada.Strings.Fixed. Did you
> submit a bug report to FSF GCC?

No, to AdaCore.