[wide-int] Make trees more like rtxes

[Richard Sandiford]

Richard Biener <rguenther@suse.de> writes:
>> The patch does that by adding:
>> 
>>   wi::address (t)
>> 
>> for when we want to extend tree t to addr_wide_int precision and:
>> 
>>   wi::extend (t)
>> 
>> for when we want to extend it to max_wide_int precision.  (Better names
>> welcome.)  These act just like addr_wide_int (t) and max_wide_int (t)
>> would on current sources, except that they use the tree representation
>> directly, so there's no copying.
>
> Good.  Better names - ah well, wi::to_max_wide_int (t) and
> wi::to_addr_wide_int (t)?  Btw, "addr_wide_int" is an odd name as it
> has at least the precision of the maximum _bit_ offset possible, right?
> So more like [bit_]offset_wide_int?  Or just [bit_]offset_int?
> And then wi::to_offset (t) and wi::to_max (t)?

offset_int, max_int, wi::to_offset and wi::to_max sound OK to me.
Kenny?  Mike?

>> Most of the patch is mechanical and many of the "wi::address (...)"s
>> and "wi::extend (...)"s reinstate "addr_wide_int (...)"s and
>> "max_wide_int (...)"s from the initial implementation.  Sorry for the
>> run-around on this.
>> 
>> One change I'd like to point out though is:
>> 
>> @@ -7287,7 +7287,9 @@ native_encode_int (const_tree expr, unsi
>>    for (byte = 0; byte < total_bytes; byte++)
>>      {
>>        int bitpos = byte * BITS_PER_UNIT;
>> -      value = wi::extract_uhwi (expr, bitpos, BITS_PER_UNIT);
>> +      /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
>> +	 number of bytes.  */
>> +      value = wi::extract_uhwi (wi::extend (expr), bitpos, BITS_PER_UNIT);
>>  
>>        if (total_bytes > UNITS_PER_WORD)
>>  	{
>> 
>> I think this preserves the existing trunk behaviour but I wasn't sure
>> whether it was supposed to work like that or whether upper bits should
>> be zero.
>
> I think the upper bits are undefined, the trunk native_interpret_int
> does
>
>   result = double_int::from_buffer (ptr, total_bytes);
>
>   return double_int_to_tree (type, result);
>
> where the call to double_int_to_tree re-extends according to the types
> precision and sign.  wide_int_to_tree doesn't though?

This is native_encode_int rather than native_interpret_int though.
AIUI it's used for VIEW_CONVERT_EXPRs, so I thought the upper bits
might get used.

Thanks,
Richard