[PATCH v3 07/12] softfloat: Fix BAD_SHIFT from normalizeFloatx80Subnormal

[Alex Bennée]

From: Richard Henderson <address@hidden>

All other calls to normalize*Subnormal detect zero input before
the call -- this is the only outlier.  This case can happen with
+0.0 + +0.0 = +0.0 or -0.0 + -0.0 = -0.0, so return a zero of
the correct sign.

Reported-by: Coverity (CID 1421991)
Signed-off-by: Richard Henderson <address@hidden>
Signed-off-by: Alex Bennée <address@hidden>
Message-Id: <address@hidden>
---
 fpu/softfloat.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 301ce3b537b..ae6ba718540 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -5856,6 +5856,9 @@ static floatx80 addFloatx80Sigs(floatx80 a, floatx80 b, 
flag zSign,
         zSig1 = 0;
         zSig0 = aSig + bSig;
         if ( aExp == 0 ) {
+            if (zSig0 == 0) {
+                return packFloatx80(zSign, 0, 0);
+            }
             normalizeFloatx80Subnormal( zSig0, &zExp, &zSig0 );
             goto roundAndPack;
         }
-- 
2.20.1