[PATCH v4 1/6] fpu/softfloat: Silence 'bitwise negation of boolean expression' warning

[Richard Henderson <richard.henderson@linaro.org>]

From: Philippe Mathieu-Daudé <philmd@redhat.com>

When building with clang version 10.0.0-4ubuntu1, we get:

    CC      lm32-softmmu/fpu/softfloat.o
  fpu/softfloat.c:3365:13: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
      absZ &= ~ ( ( ( roundBits ^ 0x40 ) == 0 ) & roundNearestEven );
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  fpu/softfloat.c:3423:18: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
          absZ0 &= ~ ( ( (uint64_t) ( absZ1<<1 ) == 0 ) & roundNearestEven );
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  ...

  fpu/softfloat.c:4273:18: error: bitwise negation of a boolean expression; did you mean logical negation? [-Werror,-Wbool-operation]
          zSig1 &= ~ ( ( zSig2 + zSig2 == 0 ) & roundNearestEven );
                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix by rewriting the fishy bitwise AND of two bools as an int.

Suggested-by: Eric Blake <eblake@redhat.com>
Buglink: https://bugs.launchpad.net/bugs/1881004
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200528155420.9802-1-philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 fpu/softfloat.c | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 6c8f2d597a..5e9746c287 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -3362,7 +3362,9 @@ static int32_t roundAndPackInt32(bool zSign, uint64_t absZ,
     }
     roundBits = absZ & 0x7F;
     absZ = ( absZ + roundIncrement )>>7;
-    absZ &= ~ ( ( ( roundBits ^ 0x40 ) == 0 ) & roundNearestEven );
+    if (!(roundBits ^ 0x40) && roundNearestEven) {
+        absZ &= ~1;
+    }
     z = absZ;
     if ( zSign ) z = - z;
     if ( ( absZ>>32 ) || ( z && ( ( z < 0 ) ^ zSign ) ) ) {
@@ -3420,7 +3422,9 @@ static int64_t roundAndPackInt64(bool zSign, uint64_t absZ0, uint64_t absZ1,
     if ( increment ) {
         ++absZ0;
         if ( absZ0 == 0 ) goto overflow;
-        absZ0 &= ~ ( ( (uint64_t) ( absZ1<<1 ) == 0 ) & roundNearestEven );
+        if (!(absZ1 << 1) && roundNearestEven) {
+            absZ0 &= ~1;
+        }
     }
     z = absZ0;
     if ( zSign ) z = - z;
@@ -3480,7 +3484,9 @@ static int64_t roundAndPackUint64(bool zSign, uint64_t absZ0,
             float_raise(float_flag_invalid, status);
             return UINT64_MAX;
         }
-        absZ0 &= ~(((uint64_t)(absZ1<<1) == 0) & roundNearestEven);
+        if (!(absZ1 << 1) && roundNearestEven) {
+            absZ0 &= ~1;
+        }
     }
 
     if (zSign && absZ0) {
@@ -3603,7 +3609,9 @@ static float32 roundAndPackFloat32(bool zSign, int zExp, uint32_t zSig,
         status->float_exception_flags |= float_flag_inexact;
     }
     zSig = ( zSig + roundIncrement )>>7;
-    zSig &= ~ ( ( ( roundBits ^ 0x40 ) == 0 ) & roundNearestEven );
+    if (!(roundBits ^ 0x40) && roundNearestEven) {
+        zSig &= ~1;
+    }
     if ( zSig == 0 ) zExp = 0;
     return packFloat32( zSign, zExp, zSig );
 
@@ -3757,7 +3765,9 @@ static float64 roundAndPackFloat64(bool zSign, int zExp, uint64_t zSig,
         status->float_exception_flags |= float_flag_inexact;
     }
     zSig = ( zSig + roundIncrement )>>10;
-    zSig &= ~ ( ( ( roundBits ^ 0x200 ) == 0 ) & roundNearestEven );
+    if (!(roundBits ^ 0x200) && roundNearestEven) {
+        zSig &= ~1;
+    }
     if ( zSig == 0 ) zExp = 0;
     return packFloat64( zSign, zExp, zSig );
 
@@ -3983,8 +3993,9 @@ floatx80 roundAndPackFloatx80(int8_t roundingPrecision, bool zSign,
             }
             if ( increment ) {
                 ++zSig0;
-                zSig0 &=
-                    ~ ( ( (uint64_t) ( zSig1<<1 ) == 0 ) & roundNearestEven );
+                if (!(zSig1 << 1) && roundNearestEven) {
+                    zSig0 &= ~1;
+                }
                 if ( (int64_t) zSig0 < 0 ) zExp = 1;
             }
             return packFloatx80( zSign, zExp, zSig0 );
@@ -4000,7 +4011,9 @@ floatx80 roundAndPackFloatx80(int8_t roundingPrecision, bool zSign,
             zSig0 = UINT64_C(0x8000000000000000);
         }
         else {
-            zSig0 &= ~ ( ( (uint64_t) ( zSig1<<1 ) == 0 ) & roundNearestEven );
+            if (!(zSig1 << 1) && roundNearestEven) {
+                zSig0 &= ~1;
+            }
         }
     }
     else {
@@ -4270,7 +4283,9 @@ static float128 roundAndPackFloat128(bool zSign, int32_t zExp,
     }
     if ( increment ) {
         add128( zSig0, zSig1, 0, 1, &zSig0, &zSig1 );
-        zSig1 &= ~ ( ( zSig2 + zSig2 == 0 ) & roundNearestEven );
+        if ((zSig2 + zSig2 == 0) && roundNearestEven) {
+            zSig1 &= ~1;
+        }
     }
     else {
         if ( ( zSig0 | zSig1 ) == 0 ) zExp = 0;
-- 
2.25.1