[PATCH] tile: Fix up corner cases with signed relocations

[Rich Felker]

On Fri, Sep 05, 2014 at 11:40:20PM +0200, Andreas Schwab wrote:
> Chris Metcalf <cmetcalf@tilera.com> writes:
> 
> > On 9/5/2014 4:33 PM, Andreas Schwab wrote:
> >> Chris Metcalf <cmetcalf@tilera.com> writes:
> >>
> >>> @@ -686,13 +686,17 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc,
> >>>     tile_bundle_bits *p = (tile_bundle_bits *) reloc_addr;
> >>>     tile_bundle_bits bits = *p;
> >>>   -#define MUNGE(func) do {
> >>> \
> >>> +#define MUNGE_SIGNED(func, length) do {                             \
> >>>       bits = ((bits & ~create_##func (-1)) | create_##func (value));  \
> >>> -    if (get_##func (bits) != value)                                 \
> >>> +    ElfW(Addr) result = (long) get_##func (bits)                    \
> >>> +      << (__WORDSIZE - length) >> (__WORDSIZE - length);            \
> >> Left shifting a negative value has undefined value.
> >
> > The shift is always a non-negative value less than __WORDSIZE
> > here, by intention. Are you seeing something I'm missing?
> 
> I'm talking about the value, not the shift amount.

In general, this issue should always be solvable, in cases where
overflow won't happen, by replacing a<<b with a*(1<<b).

Rich