[PATCH] Add if-chain to switch conversion pass.

[Martin Liška]

On 10/2/20 4:19 PM, Andrew MacLeod wrote:
> On 10/2/20 9:26 AM, Martin Liška wrote:
>>> Yes, you simply get all sorts of conditions that hold when a condition is
>>> true, not just those based on the SSA name you put in.  But it occured
>>> to me that the use-case is somewhat different - for switch-conversion
>>> you want to know whether the test _exactly_ matches a range test,
>>> the VRP worker will not tell you that.  For example if you had
>>> if (x &&  a > 3 && a < 7) then it will give you 'a in [4, 6]' and it might
>>> not give you 'x in [1, 1]' (for example if x is float).  But that's required
>>> for correctness.
>>
>> Hello.
>>
>> Adding Ranger guys. Is it something that can be handled by the upcoming changes in VRP?
> 
> Presumably. It depends on exactly how the code lays out.  We dont process floats, so we wont know anything about the float (at least this release :-).  We will sort through complex logicals and tell you what we do know, so if x is integral
> 
> 
>     if (x &&  a > 3 && a < 7)
> 
> will give you, on the final true edge:
> 
> x_5(D)  int [-INF, -1][1, +INF]
> a_6(D)  int [4, 6]
> 
> 
> IF x is a float, then we wont give you anything for x obviously, but on the eventual true edge we'd still give you
> a_6(D)  int [4, 6]

Which is an acceptable limitation for me.

However, I can't convince ranger to give me a proper ranges for. I'm using the following
code snippet:

   outgoing_range query;

   edge e;
   edge_iterator ei;
   FOR_EACH_EDGE (e, ei, bb->succs)
     {
       int_range_max range;
       if (query.edge_range_p (range, e))
	{
	  if (dump_file)
	    {
	  fprintf (dump_file, "%d->%d: ", e->src->index, e->dest->index);
	  range.dump(dump_file);
	  fprintf (dump_file, "\n");
	    }
	}
     }


if (9 <= index && index <= 123)
     return 123;

   <bb 2> :
   index.0_1 = (unsigned int) index_5(D);
   _2 = index.0_1 + 4294967287;
   if (_2 <= 114)
     goto <bb 3>; [INV]
   else
     goto <bb 4>; [INV]

I get:

2->3: _Bool [1, 1]
2->4: _Bool [0, 0]

Can I get to index_5 [9, 123] ?
Thanks,
Martin

> 
> 
> Andrew
> 
> 
>