commit 2f311075b7a74124098effc72290767b02869561
author Richard Henderson <richard.henderson@linaro.org> Fri Apr 03 20:11:45 2020 +0100
committer Alex Bennée <alex.bennee@linaro.org> Tue Apr 07 16:19:49 2020 +0100
tree 1f4030db3d55cb7c3dffe2e034b3d5fb4060f920
parent 076b2fadb582e4734a879f843885dad38cf91526

softfloat: Fix BAD_SHIFT from normalizeFloatx80Subnormal

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 <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200327232042.10008-1-richard.henderson@linaro.org>
Message-Id: <20200403191150.863-8-alex.bennee@linaro.org>

fpu/softfloat.c

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 301ce3b..ae6ba71 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -5856,6 +5856,9 @@
         zSig1 = 0;
         zSig0 = aSig + bSig;
         if ( aExp == 0 ) {
+            if (zSig0 == 0) {
+                return packFloatx80(zSign, 0, 0);
+            }
             normalizeFloatx80Subnormal( zSig0, &zExp, &zSig0 );
             goto roundAndPack;
         }