> On Mon, Nov 12, 2018 at 6:03 PM Eduardo Habkost <ehabk...@redhat.com> wrote:
> > On Mon, Nov 12, 2018 at 12:36:16AM +0100, Philippe Mathieu-Daudé wrote:
> > > Python internal representation is signed, so unsigned values
> > > bigger than 31-bit are interpreted as signed (and printed with
> > > a '-' signed).
> > > Mask out to force unsigned values.
> >
> > I don't understand this commit description. Python surely
> > supports integers larger than 2^31, and its internal
> > representation shouldn't matter at all:
> >
> > >>>
> > '0x{0:08x}'.format(0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff)
> >
> > '0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff'
>>> '0x{0:08x}'.format(-1)
'0x-0000001'
> >
> > Can you explain how the code ends up with a negative value in the
> > `self.thismask` or `b` variables? If `self.subs` contains
> > negative values, this is likely to break other parts of the code.
>
> I guess I misunderstood the error, thus the description is invalid.
>
> >
> > >
> > > Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org>
> > > ---
> > > TODO: display error encountered:
> > >
> > > case 0x-1:
> > > ....
> >
> > How can I reproduce it?
>
> $ scripts/decodetree.py /dev/null
>
> switch (insn & 0x-0000001) {
> }
>
> main() ->
> build_tree(patterns, 0, outermask = 0) ->
> innermask = ~outermask # = -1
> Tree(fullmask, innermask = -1) ->
> __init__(self, fm, tm = -1) ->
> self.thismask = tm # -1
> t.output_code(4, False, 0, 0) ->
> sh = is_contiguous(self.thismask) # -1
> output(ind, 'switch (', str_switch(self.thismask), ') {\n')
>
> with:
>
> def str_switch(b):
> return 'insn & 0x{0:08x}'.format(b)
>
> So the fix is rather:
>
> -- >8 --
> diff --git a/scripts/decodetree.py b/scripts/decodetree.py
> @@ -916,7 +916,7 @@ class Tree:
>
> def build_tree(pats, outerbits, outermask):
> # Find the intersection of all remaining fixedmask.
> - innermask = ~outermask
> + innermask = ~outermask & insnmask
> for i in pats:
> innermask &= i.fixedmask
> ---
