Re: [PATCH] PR32219, weak hidden reference segfault

[Chung-Lin Tang <cltang at codesourcery dot com>]

On 13/5/10 6:37 PM, Richard Sandiford wrote:
> Chung-Lin Tang <cltang@codesourcery.com> writes:
>> +    case UNSPEC:
>> +      /* Reach for a contained symbol.  */
>> +      return nonzero_address_p (XVECEXP (x, 0, 0));
> 
> I don't think this is safe.  UNSPECs really are unspecified :-),
> so we can't assume that (unspec X) is nonzero simply because X is.

Attached is a modified patch (not yet tested but just for demonstration)
with a more specific test, hopefully regarded as more safe.

The point is in recognizing (const (unspec [symbol] XYZ)) offsets in PIC
references, which seems quite idiomatic across all targets by now.

I would suggest that this probably means there should be a new, more
specific construct in RTL to represent relocation values of this kind,
instead of (const (unspec)) serving an unofficial role; possibly some
real support for reasoning about PIC references could also be considered.

Chung-Lin

Attachment: pr32219-2.patch
Description: Text document