To: eliz AT is DOT elta DOT co DOT il
Cc: gcc AT gcc DOT gnu DOT org, djgpp-workers AT delorie DOT com
References: <2 DOT 7 DOT 9 DOT 181SX DOT H8JVM1 AT pauzner DOT dnttm DOT ru>
    <2561-Sat11Jan2003175230+0200-eliz AT is DOT elta DOT co DOT il>
Message-Id: <2.7.9.SBA.H8K8TU@pauzner.dnttm.ru>
From: "Leonid Pauzner" <uue AT pauzner DOT dnttm DOT ru>
Date: Sat, 11 Jan 2003 20:34:42 +0300 (MSK)
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Subject: Re: gcc 3.2.1 optimizer degradation (strlen, -O2)
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Reply-To: djgpp-workers AT delorie DOT com

This is a message in MIME format. Your mail reader does not support MIME :(

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11-Jan-2003 17:52 Eli Zaretskii wrote:
>> From: "Leonid Pauzner" <uue AT pauzner DOT dnttm DOT ru>
>> Date: Sat, 11 Jan 2003 15:49:13 +0300 (MSK)
>>
>> It turns out that the libc strlen() function (compiled with -O2)
>> became nearly 2 times slower when I switched from gcc 2.95.3 to gcc 3.2.1
>> on a Pentium machine.

> Are you sure you get the library strlen?  IIRC, GCC provides its own
> inline versions of some functions, and I think strlen is one of them.

> Examining the code (use the -S switch to GCC to produce it) should
> show you whether my guess was true.

Sure, there is a "call _strlen" line in the assembler code,
and I made the test program by calling
  "gcc -o strlen.exe main.o strlen.o"

This is a DJGPP environment.

The key point in my original posting was the certain simple loop
which happens to be optimized better with the old version of the compiler.
Generated assembler attached.

> You could use the -fno-builtin switch to force GCC to call the
> (non-inline) library version of strlen.


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