On 10/23/2013 08:13 AM, Richard Biener wrote:
On Wed, 23 Oct 2013, Richard Sandiford wrote:
Richard Biener <rguent...@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.
Yes, I was looking at the matched interpret variant though to see
what we do.
the wide_int_to_tree really needs to canonicalize the value before
making it into a tree.
the calls to tree_fits*_p (the successor to host_integer_p) depend on
this being clean.
Otherwise, these functions will have to clean the short integers and
they get called all over the place.
AIUI it's used for VIEW_CONVERT_EXPRs, so I thought the upper bits
might get used.
Yeah, that might happen, but still relying on the upper bits in any
way would be brittle here.
Richard.