fold() can't fold simple expressions?

[Andrew MacLeod]

On 09/14/2016 03:29 PM, Richard Biener wrote:
> On September 14, 2016 6:39:14 PM GMT+02:00, Jeff Law <law@redhat.com> wrote:
>> On 09/14/2016 08:08 AM, Andrew MacLeod wrote:
>>> range generator understands, we just thought it would be handy to
>>> leverage the folder during the proof of concept stage.
>> It's also worth noting that a backwards substitution based threading,
>> redundancy elimination, etc pass would need similar capabilities.
>>
>> Essentially you start with some gimple expression, say a + b.  You then
>>
>> start walking backwards substituting the RHS of defining statements
>> into
>> the expression and simplifying as you go.
> It's what match-and-simplify does as well.
>
> I question the need to build GENERIC here though.  M-a-s happily gets you a simplified expression as sequence of GIMPLE statements.  (But does not yet provide a way to build a simplified GENERIC expression from GIMPLE IL)
>
>
>

I'm considering alternatives and we may be able to avoid it by marking 
and delaying some evaluations...  it was just an easy way to an ends for 
prototyping.

Andrew