Re: [patch] avoid printing leading 0 in widest_int hex dumps

[Richard Sandiford <richard dot sandiford at linaro dot org>]

Aldy Hernandez <aldyh@redhat.com> writes:
> Hi folks!
>
> Calling print_hex() on a widest_int with the most significant bit turned 
> on can lead to a leading zero being printed (0x0ffff....). This produces 
> confusing dumps to say the least, especially when you incorrectly assume 
> an integer is NOT signed :).

That's the intended behaviour though.  wide_int-based types only use as
many HWIs as they need to store their current value, with any other bits
in the value being a sign extension of the top bit.  So if the most
significant HWI in a widest_int is zero, that HWI is there to say that
the previous HWI should be zero- rather than sign-extended.

So:

   0x0ffffffff  -> (1 << 32) - 1 to infinite precision
		   (i.e. a positive value)
   0xffffffff   -> -1

Thanks,
Richard