Re: [PATCH v2 03/19] PR gdb/21226: Take DWARF stack value pieces from LSB end

[Yao Qi <qiyaoltc@gmail.com>]

Andreas Arnez <arnez@linux.vnet.ibm.com> writes:

> * DW_OP_piece shall take the piece from the LSB end as well;
>

My understanding is that this is true for a given arch or ABI.  This
change will affect other big-endian architectures, like mips.

> @@ -1866,26 +1870,30 @@ read_pieced_value (struct value *v)
>  			     p->v.mem.in_stack_memory,
>  			     p->v.mem.addr + source_offset,
>  			     buffer.data (), this_size);
> +	  copy_bitwise (contents, dest_offset_bits,
> +			intermediate_buffer, source_offset_bits % 8,
> +			this_size_bits, bits_big_endian);
>  	  break;
>  
>  	case DWARF_VALUE_STACK:
>  	  {
> -	    size_t n = this_size;
> +	    struct objfile *objfile = dwarf2_per_cu_objfile (c->per_cu);
> +	    struct gdbarch *objfile_gdbarch = get_objfile_arch (objfile);
> +	    ULONGEST stack_value_size_bits
> +	      = 8 * TYPE_LENGTH (value_type (p->v.value));
>  
> -	    if (n > c->addr_size - source_offset)
> -	      n = (c->addr_size >= source_offset
> -		   ? c->addr_size - source_offset
> -		   : 0);
> -	    if (n == 0)
> -	      {
> -		/* Nothing.  */
> -	      }
> -	    else
> -	      {
> -		const gdb_byte *val_bytes = value_contents_all (p->v.value);
> +	    /* Use zeroes if piece reaches beyond stack value.  */
> +	    if (p->size > stack_value_size_bits)
> +	      break;

Does this indicate something wrong in DWARF producer?  Does GDB need to
emit a complaint?

-- 
Yao (齐尧)