[Qemu-devel] [PATCH] ppc: Fix emulated INFINITY and NAN conversions

[Qemu-devel] [PATCH] ppc: Fix emulated INFINITY and NAN conversions

[Paul A. Clarke]

From: "Paul A. Clarke" <pc@us.ibm.com>

helper_todouble() was not properly converting INFINITY from 32 bit
float to 64 bit double.

(Normalized operand conversion is unchanged, other than indentation.)

Signed-off-by: Paul A. Clarke <pc@us.ibm.com>
---
 target/ppc/fpu_helper.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/target/ppc/fpu_helper.c b/target/ppc/fpu_helper.c
index 23b9c97..52bcda2 100644
--- a/target/ppc/fpu_helper.c
+++ b/target/ppc/fpu_helper.c
@@ -58,10 +58,17 @@ uint64_t helper_todouble(uint32_t arg)
     uint64_t ret;
 
     if (likely(abs_arg >= 0x00800000)) {
-        /* Normalized operand, or Inf, or NaN.  */
-        ret  = (uint64_t)extract32(arg, 30, 2) << 62;
-        ret |= ((extract32(arg, 30, 1) ^ 1) * (uint64_t)7) << 59;
-        ret |= (uint64_t)extract32(arg, 0, 30) << 29;
+        if (unlikely(extract32(arg, 23, 8) == 0xff)) {
+            /* Inf or NAN.  */
+            ret  = (uint64_t)extract32(arg, 31, 1) << 63;
+            ret |= (uint64_t)0x7ff << 52;
+            ret |= (uint64_t)extract32(arg, 0, 23) << 29;
+        } else {
+            /* Normalized operand.  */
+            ret  = (uint64_t)extract32(arg, 30, 2) << 62;
+            ret |= ((extract32(arg, 30, 1) ^ 1) * (uint64_t)7) << 59;
+            ret |= (uint64_t)extract32(arg, 0, 30) << 29;
+        }
     } else {
         /* Zero or Denormalized operand.  */
         ret = (uint64_t)extract32(arg, 31, 1) << 63;
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH] ppc: Fix emulated INFINITY and NAN conversions

[Richard Henderson]

On 8/19/19 12:19 PM, Paul A. Clarke wrote:
> From: "Paul A. Clarke" <pc@us.ibm.com>
> 
> helper_todouble() was not properly converting INFINITY from 32 bit
> float to 64 bit double.
> 
> (Normalized operand conversion is unchanged, other than indentation.)
> 
> Signed-off-by: Paul A. Clarke <pc@us.ibm.com>
> ---
>  target/ppc/fpu_helper.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~

Re: [Qemu-devel] [PATCH] ppc: Fix emulated INFINITY and NAN conversions

[David Gibson]

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On Mon, Aug 19, 2019 at 01:57:42PM -0700, Richard Henderson wrote:
> On 8/19/19 12:19 PM, Paul A. Clarke wrote:
> > From: "Paul A. Clarke" <pc@us.ibm.com>
> > 
> > helper_todouble() was not properly converting INFINITY from 32 bit
> > float to 64 bit double.
> > 
> > (Normalized operand conversion is unchanged, other than indentation.)
> > 
> > Signed-off-by: Paul A. Clarke <pc@us.ibm.com>
> > ---
> >  target/ppc/fpu_helper.c | 15 +++++++++++----
> >  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Applied to ppc-for-4.2, thanks.

> 
> 
> r~
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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