wide-int: Fix up set_bit_large

> >> wide_int new_lb = wi::set_bit (r.lower_bound (0), 127)
> >>
> >> and creates the value:
> >>
> >> p new_lb
> >> {<wide_int_storage> = {val = {-65535, -1, 0}, len = 2, precision = 128},
> >> static is_sign_extended = true}
> >
> > This is non-canonical and so invalid, if the low HWI has the MSB set
> > and the high HWI is -1, it should have been just
> > val = {-65535}, len = 1, precision = 128}
> >
> > I guess the bug is that wi::set_bit_large doesn't call canonize.
>
> Yeah, looks like a micro-optimisation gone wrong.

2020-10-28  Jakub Jelinek  <jakub@redhat.com>

	* wide-int.cc (wi::set_bit_large): Call canonize unless setting
	msb bit and clearing bits above it.

diff --git a/gcc/wide-int.cc b/gcc/wide-int.cc
index 03be0074816dd50ea56afffd442a1935010f8836..4c29ef832457b48bb0370eeeab024ef2318c643d 100644 (file)
--- a/gcc/wide-int.cc
+++ b/gcc/wide-int.cc
@@ -702,8 +702,11 @@ wi::set_bit_large (HOST_WIDE_INT *val, const HOST_WIDE_INT *xval,
       /* If the bit we just set is at the msb of the block, make sure
         that any higher bits are zeros.  */
       if (bit + 1 < precision && subbit == HOST_BITS_PER_WIDE_INT - 1)
-       val[len++] = 0;
-      return len;
+       {
+         val[len++] = 0;
+         return len;
+       }
+      return canonize (val, len, precision);
     }
   else
     {