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Date: Wed, 09 Jun 2010 18:44:00 -0000
From: Jan Kratochvil <jan.kratochvil@redhat.com>
To: Tom Tromey <tromey@redhat.com>
Cc: gdb-patches@sourceware.org
Subject: Re: RFC: optimized-out pieces
Message-ID: <20100609184356.GA23679@host0.dyn.jankratochvil.net>
References: <m3typivc5b.fsf@fleche.redhat.com> <20100607223524.GA2897@host0.dyn.jankratochvil.net> <m3ocfljrsb.fsf@fleche.redhat.com> <20100608184224.GA6814@host0.dyn.jankratochvil.net> <m3iq5tjqsj.fsf@fleche.redhat.com>
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> +static int
> +check_pieced_value_validity (const struct value *value, int bit_offset,
> +			     int bit_length)
> +{
> +  struct piece_closure *c
> +    = (struct piece_closure *) value_computed_closure (value);
> +  int i;
> +
> +  bit_offset += 8 * value_offset (value);

I miss some `value_bitpos (value)' possibility here.


> +  for (i = 0; i < c->n_pieces && bit_length > 0; i++)
> +    {
> +      struct dwarf_expr_piece *p = &c->pieces[i];
> +      size_t this_size_bits = p->size;
> +
> +      if (bit_offset > 0)
> +	{
> +	  if (bit_offset >= this_size_bits)
> +	    {
> +	      bit_offset -= this_size_bits;
> +	      continue;
> +	    }
> +
> +	  bit_length -= bit_offset;

Here should be `bit_length -= this_size_bits - bit_offset'.

If we heve:
	this_size_bits = 8
	bit_offset = 7
	bit_length = 2
then your code does
	bit_length -= 7; bit_length = -5;
while for the next piece it should be:
	bit_length -= 1; bit_length = 1;


> +	  bit_offset = 0;
> +	}
> +      else
> +	bit_length -= this_size_bits;
> +
> +      if (p->location == DWARF_VALUE_OPTIMIZED_OUT)
> +	return 0;
> +    }
> +
> +  return 1;
> +}


Thanks,
Jan