(immed_double_const): Sign-extend constants when they

have the most significant bit set for the target.

From-SVN: r7027

diff --git a/gcc/varasm.c b/gcc/varasm.c
index 17117c0f8b48b223ec09f16bc1ecd2367c99eace..a09852acc93dec07caa1ab30ab32054cfa8473b3 100644 (file)
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -1785,6 +1785,19 @@ immed_double_const (i0, i1, mode)
        /* We cannot represent this value as a constant.  */
        abort ();
 
+      /* If this would be an entire word for the target, but is not for
+        the host, then sign-extend on the host so that the number will look
+        the same way on the host that it would on the target.
+
+        For example, when building a 64 bit alpha hosted 32 bit sparc
+        targeted compiler, then we want the 32 bit unsigned value -1 to be
+        represented as a 64 bit value -1, and not as 0x00000000ffffffff.
+        The later confuses the sparc backend.  */
+
+      if (BITS_PER_WORD < HOST_BITS_PER_WIDE_INT && BITS_PER_WORD == width
+         && (i0 & ((HOST_WIDE_INT) 1 << (width - 1))))
+       i0 |= ((HOST_WIDE_INT) (-1) << width);
+
       /* If MODE fits within HOST_BITS_PER_WIDE_INT, always use a CONST_INT.
 
         ??? Strictly speaking, this is wrong if we create a CONST_INT