Date: Tue, 17 Dec 2002 15:40:03 -0800 (PST) From: Mikhail Teterin <mi+mx@aldan.algebra.com> To: freebsd-bugs@FreeBSD.org Subject: Re: bin/43299: march=pentium4 miscompiles msun/src/e_pow.c Message-ID: <200212172340.gBHNe3x8088438@freefall.freebsd.org>
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The following reply was made to PR bin/43299; it has been noted by GNATS.
From: Mikhail Teterin <mi+mx@aldan.algebra.com>
To: freebsd-gnats-submit@FreeBSD.org, mi@aldan.algebra.com
Cc: deischen@FreeBSD.org, bde@FreeBSD.org
Subject: Re: bin/43299: march=pentium4 miscompiles msun/src/e_pow.c
Date: Tue, 17 Dec 2002 18:41:46 -0500
The described problem no longer exists. Probably -- thanks to the
recent commit:
deischen 2002/12/02 11:58:55 PST
Modified files:
sys/i386/i386 genassym.c locore.s machdep.c
sys/i386/include signal.h ucontext.h
Log:
Align the FPU state in the ucontext and sigcontext to 16 bytes
to accomodate the new SSE/XMM floating point save/restore
instructions.
This commit is mostly from bde and includes some style nits.
Approved by: re (jhb)
However, on my 2GHz Pentium4, the pow(3) is between 10 to 15%
slower, when compiled for pentium4, than it is, when compiled
for pentium3. The little program follows. It prints out the
results of the explicit __ieee754_pow(), and than goes to work.
#include <math.h>
#include <stdio.h>
double __ieee754_pow(double, double);
int main() {
int i;
printf("%g^%g is %g\n", 2.0, 2.1, __ieee754_pow(2.0, 2.1));
printf("%g^%g is %g\n", 11.0, -2.1, __ieee754_pow(11.0, -2.1));
for (i = 0; i < 10000000; i++)
__ieee754_pow(11.0, -2.1);
return 0;
}
I compile it (named t.c) as follows:
cd /usr/src/lib/msun/src
cc $FLAGS t.c e_exp.c ../i387/s_scalbn.S ../i387/e_sqrt.S e_pow.c
To exclude the effects of the precompiled -lm.
-mi
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