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[MIPS] ieee754[sd]p_neg workaround

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It looks glibc's pow() assumes an unary '-' operation for any number
(including NaNs) always inverts its sign bit (though IEEE754 does not
specify the sign bit for NaNs).  This patch make the kernel math-emu
emulates real MIPS neg.[ds] instruction.
    
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Atsushi Nemoto 2006-01-02 21:59:49 +09:00 committed by Ralf Baechle
parent d4264f1839
commit c5033d7803
2 changed files with 20 additions and 8 deletions
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14
arch/mips/math-emu/dp_simple.c
View file

@ -48,16 +48,22 @@ ieee754dp ieee754dp_neg(ieee754dp x)
CLEARCX;
FLUSHXDP;
/*
* Invert the sign ALWAYS to prevent an endless recursion on
* pow() in libc.
*/
/* quick fix up */
DPSIGN(x) ^= 1;
if (xc == IEEE754_CLASS_SNAN) {
ieee754dp y = ieee754dp_indef();
SETCX(IEEE754_INVALID_OPERATION);
return ieee754dp_nanxcpt(ieee754dp_indef(), "neg");
DPSIGN(y) = DPSIGN(x);
return ieee754dp_nanxcpt(y, "neg");
}
if (ieee754dp_isnan(x)) /* but not infinity */
return ieee754dp_nanxcpt(x, "neg", x);
/* quick fix up */
DPSIGN(x) ^= 1;
return x;
}

14
arch/mips/math-emu/sp_simple.c
View file

@ -48,16 +48,22 @@ ieee754sp ieee754sp_neg(ieee754sp x)
CLEARCX;
FLUSHXSP;
/*
* Invert the sign ALWAYS to prevent an endless recursion on
* pow() in libc.
*/
/* quick fix up */
SPSIGN(x) ^= 1;
if (xc == IEEE754_CLASS_SNAN) {
ieee754sp y = ieee754sp_indef();
SETCX(IEEE754_INVALID_OPERATION);
return ieee754sp_nanxcpt(ieee754sp_indef(), "neg");
SPSIGN(y) = SPSIGN(x);
return ieee754sp_nanxcpt(y, "neg");
}
if (ieee754sp_isnan(x)) /* but not infinity */
return ieee754sp_nanxcpt(x, "neg", x);
/* quick fix up */
SPSIGN(x) ^= 1;
return x;
}