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Re: wide-int, C++ front end

On Mon, Nov 25, 2013 at 9:05 PM, Richard Sandiford
<> wrote:
> Jason Merrill <> writes:
>> On 11/23/2013 02:20 PM, Mike Stump wrote:
>>> @@ -2605,8 +2606,7 @@ cp_tree_equal (tree t1, tree t2)
>>>     switch (code1)
>>>       {
>>>       case INTEGER_CST:
>>> -      return TREE_INT_CST_LOW (t1) == TREE_INT_CST_LOW (t2)
>>> -    && TREE_INT_CST_HIGH (t1) == TREE_INT_CST_HIGH (t2);
>>> +      return wi::to_widest (t1) == wi::to_widest (t2);
>> Why not use wi::eq_p like you do in the C front end?
> Thanks for noticing the difference.  I think c_tree_equal should change
> to use to_widest too.
> wi::eq_p (t1, t2) asserts that t1 and t2 are the same precision and
> ignores signedness; it just tests whether they are the same bitstring.
> wi::to_widest (t1) == wi::to_widest (t2) compares them as logical numbers,
> taking sign into account and allowing different types.  I think that's
> what the original TREE_INT_CST_LOW and TREE_INT_CST_HIGH tests did too.

Though in this case (comparing two INTEGER_CSTs) it would be better
to use a tree abstraction - thus tree_int_cst_equal.  It saves us from
making the decision on what to map this in wide-int to multiple times.

Note that tree_int_cst_equal tests for "same constant value" - in tree
terms this includes sign information and thus requires to_widest.


> Richard

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