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[PATCH v3 10/16] MIPS: math-emu: MINA.<D|S>: Fix some cases of infinity and zero inputs

Started byAleksandar Markovic <aleksandar.markovic@rt-rk.com>
First post2017-07-21 16:20 +0200
Last post2017-07-21 18:10 +0200
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  [PATCH v3 10/16] MIPS: math-emu: MINA.<D|S>: Fix some cases of infinity and zero inputs Aleksandar Markovic <aleksandar.markovic@rt-rk.com> - 2017-07-21 16:20 +0200
    Re: [PATCH v3 10/16] MIPS: math-emu: MINA.<D|S>: Fix some cases of  infinity and zero inputs James Hogan <james.hogan@imgtec.com> - 2017-07-21 18:10 +0200

#1693735 — [PATCH v3 10/16] MIPS: math-emu: MINA.<D|S>: Fix some cases of infinity and zero inputs

FromAleksandar Markovic <aleksandar.markovic@rt-rk.com>
Date2017-07-21 16:20 +0200
Subject[PATCH v3 10/16] MIPS: math-emu: MINA.<D|S>: Fix some cases of infinity and zero inputs
Message-ID<u5GWC-5Tl-33@gated-at.bofh.it>
From: Aleksandar Markovic <aleksandar.markovic@imgtec.com>

Fix following special cases for MINA>.<D|S>:

  - if one of the inputs is zero, and the other is subnormal, normal,
    or infinity, the  value of the former should be returned (that is,
    a zero).
  - if one of the inputs is infinity, and the other input is normal,
    or subnormal, the value of the latter should be returned.

The previous implementation's logic for such cases was incorrect - it
appears as if it implements MAXA, and not MINA instruction.

The relevant example:

MINA.S fd,fs,ft:
  If fs contains 100.0, and ft contains 0.0, fd is going to contain
  0.0 (without this patch, it used to contain 100.0).

Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>
Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
---
 arch/mips/math-emu/dp_fmin.c | 4 ++--
 arch/mips/math-emu/sp_fmin.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/mips/math-emu/dp_fmin.c b/arch/mips/math-emu/dp_fmin.c
index d4cd243..1e9ee3d 100644
--- a/arch/mips/math-emu/dp_fmin.c
+++ b/arch/mips/math-emu/dp_fmin.c
@@ -191,14 +191,14 @@ union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y)
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
-		return x;
+		return y;
 
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
-		return y;
+		return x;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
 		return ieee754dp_zero(xs | ys);
diff --git a/arch/mips/math-emu/sp_fmin.c b/arch/mips/math-emu/sp_fmin.c
index 5f1d650..685ce75 100644
--- a/arch/mips/math-emu/sp_fmin.c
+++ b/arch/mips/math-emu/sp_fmin.c
@@ -192,14 +192,14 @@ union ieee754sp ieee754sp_fmina(union ieee754sp x, union ieee754sp y)
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
-		return x;
+		return y;
 
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
-		return y;
+		return x;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
 		return ieee754sp_zero(xs | ys);
-- 
2.7.4

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#1693820 — Re: [PATCH v3 10/16] MIPS: math-emu: MINA.<D|S>: Fix some cases of infinity and zero inputs

FromJames Hogan <james.hogan@imgtec.com>
Date2017-07-21 18:10 +0200
SubjectRe: [PATCH v3 10/16] MIPS: math-emu: MINA.<D|S>: Fix some cases of infinity and zero inputs
Message-ID<u5IF3-708-3@gated-at.bofh.it>
In reply to#1693735

[Multipart message — attachments visible in raw view] — view raw

On Fri, Jul 21, 2017 at 04:09:08PM +0200, Aleksandar Markovic wrote:
> From: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
> 
> Fix following special cases for MINA>.<D|S>:
> 
>   - if one of the inputs is zero, and the other is subnormal, normal,
>     or infinity, the  value of the former should be returned (that is,
>     a zero).
>   - if one of the inputs is infinity, and the other input is normal,
>     or subnormal, the value of the latter should be returned.
> 
> The previous implementation's logic for such cases was incorrect - it
> appears as if it implements MAXA, and not MINA instruction.
> 
> The relevant example:
> 
> MINA.S fd,fs,ft:
>   If fs contains 100.0, and ft contains 0.0, fd is going to contain
>   0.0 (without this patch, it used to contain 100.0).

Another ouch!

> 

Fixes/stable

> Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>
> Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com>
> Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>

Reviewed-by: James Hogan <james.hogan@imgtec.com>

Cheers
James

> ---
>  arch/mips/math-emu/dp_fmin.c | 4 ++--
>  arch/mips/math-emu/sp_fmin.c | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/mips/math-emu/dp_fmin.c b/arch/mips/math-emu/dp_fmin.c
> index d4cd243..1e9ee3d 100644
> --- a/arch/mips/math-emu/dp_fmin.c
> +++ b/arch/mips/math-emu/dp_fmin.c
> @@ -191,14 +191,14 @@ union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y)
>  	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
>  	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
>  	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
> -		return x;
> +		return y;
>  
>  	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
>  	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
>  	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
>  	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
>  	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
> -		return y;
> +		return x;
>  
>  	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
>  		return ieee754dp_zero(xs | ys);
> diff --git a/arch/mips/math-emu/sp_fmin.c b/arch/mips/math-emu/sp_fmin.c
> index 5f1d650..685ce75 100644
> --- a/arch/mips/math-emu/sp_fmin.c
> +++ b/arch/mips/math-emu/sp_fmin.c
> @@ -192,14 +192,14 @@ union ieee754sp ieee754sp_fmina(union ieee754sp x, union ieee754sp y)
>  	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
>  	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
>  	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
> -		return x;
> +		return y;
>  
>  	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
>  	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
>  	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
>  	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
>  	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
> -		return y;
> +		return x;
>  
>  	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
>  		return ieee754sp_zero(xs | ys);
> -- 
> 2.7.4
> 

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