Removed unnecessary checks, added TODO note.

Author: vzakhari

flang/lib/Optimizer/HLFIR/Transforms/OptimizedBufferization.cpp

@@ -338,35 +338,20 @@ ElementalAssignBufferization::findMatch(hlfir::ElementalOp elemental) {
   if (!fir::isa_trivial(eleTy))
     return std::nullopt;
 
-  // The array must have the same shape as the elemental. CSE should have
-  // deduplicated the fir.shape operations where they are provably the same
-  // so we just have to check for the same ssa value.
+  // The array must have the same shape as the elemental.
   //
   // f2018 10.2.1.2 (3) requires the lhs and rhs of an assignment to be
   // conformable unless the lhs is an allocatable array. In HLFIR we can
   // see this from the presence or absence of the realloc attribute on
   // hlfir.assign. If it is not a realloc assignment, we can trust that
   // the shapes do conform.
-  if (match.assign.getRealloc()) {
-    mlir::Value arrayShape;
-    if (match.array.getDefiningOp())
-      arrayShape =
-          mlir::TypeSwitch<mlir::Operation *, mlir::Value>(
-              match.array.getDefiningOp())
-              .Case([](hlfir::DesignateOp designate) {
-                return designate.getShape();
-              })
-              .Case([](hlfir::DeclareOp declare) { return declare.getShape(); })
-              .Default([](mlir::Operation *) { return mlir::Value{}; });
-    if (!arrayShape) {
-      // TODO: add more ways of getting the shape of the array
-      LLVM_DEBUG(llvm::dbgs() << "Can't get shape of " << match.array << " at "
-                              << elemental->getLoc() << "\n");
-      return std::nullopt;
-    }
-    if (arrayShape != elemental.getShape())
-      return std::nullopt;
-  }
+  //
+  // TODO: the lhs's shape is dynamic, so it is hard to prove that
+  // there is no reallocation of the lhs due to the assignment.
+  // We can probably try generating multiple versions of the code
+  // with checking for the shape match, length parameters match, etc.
+  if (match.assign.getRealloc())
+    return std::nullopt;
 
   // the transformation wants to apply the elemental in a do-loop at the
   // hlfir.assign, check there are no effects which make this unsafe