[MLIR][Linalg] Fix assertion in dependency analysis

[frgossen]

Summary

The assertion falsely expected ranked memrefs only. Now both, ranked and
unranked memrefs are allowed.

[nicolasvasilache]

What does it mean for a linalg op to take unranked memref?
In particular, a linalg op has indexing_maps. of fixed rank.
How would that work with unranked stuff ?

[pifon2a]

In D88080#2287348, @nicolasvasilache wrote:

What does it mean for a linalg op to take unranked memref?
In particular, a linalg op has indexing_maps. of fixed rank.
How would that work with unranked stuff ?

I don't think it really takes unranked memref here. We have reshape op that changes descriptor from unranked to ranked and this op has ViewLikeOpInterface. But we hit this assert if we use the output of this op. Or maybe i am missing smth.

mlir/lib/Dialect/Linalg/Analysis/DependenceAnalysis.cpp

 using llvm::dbgs;
 
 Value Aliases::find(Value v) {
   if (v.isa<BlockArgument>())
     return v;
 
   auto it = aliases.find(v);
   if (it != aliases.end()) {
-    assert(it->getSecond().getType().isa<MemRefType>() && "Memref expected");
+    assert(it->getSecond().getType().isa<BaseMemRefType>() &&
+           "Memref expected");
     return it->getSecond();
   }
 
   while (true) {
     if (v.isa<BlockArgument>())
       return v;
 
     Operation *defOp = v.getDefiningOp();