[Layout] Support layout forward with multi dimension (#867)

* Enhance LayoutNode::Forward method to handle variable transformations more robustly

- Updated the method to check for a minimum number of input dimensions.
- Introduced a mechanism to transform the last InputDim() elements of the input variables.
- Concatenated transformed variables with the remaining input variables for a comprehensive output.

* Refactor LayoutNode::Forward method for improved readability

- Removed unnecessary whitespace to enhance code clarity.
- Maintained existing functionality while streamlining the transformation process of input variables.

Author: LeiWang1999

src/layout/layout.cc

@@ -115,13 +115,32 @@ Array<PrimExpr> LayoutNode::OutputShape() const {
 Array<PrimExpr> LayoutNode::Forward(const Array<PrimExpr> &vars) const {
   if (vars.empty())
     return forward_index_;
-  ICHECK_EQ(vars.size(), InputDim());
+  ICHECK_GE(vars.size(), InputDim());
+
+  // Take the last InputDim() elements for transformation
+  Array<PrimExpr> transform_vars;
+  for (size_t i = vars.size() - InputDim(); i < vars.size(); i++) {
+    transform_vars.push_back(vars[i]);
+  }
+
   Map<Var, PrimExpr> vmap;
   for (size_t i = 0; i < InputDim(); i++) {
-    vmap.Set(InputPlaceholder(i), vars[i]);
+    vmap.Set(InputPlaceholder(i), transform_vars[i]);
   }
-  return forward_index_.Map(
+
+  Array<PrimExpr> transformed = forward_index_.Map(
       [&](const PrimExpr &e) { return Substitute(e, vmap); });
+
+  // Concatenate with the remaining elements from vars
+  Array<PrimExpr> result;
+  for (size_t i = 0; i < vars.size() - InputDim(); i++) {
+    result.push_back(vars[i]);
+  }
+  for (const auto &expr : transformed) {
+    result.push_back(expr);
+  }
+
+  return result;
 }
 
 Fragment FragmentNode::Repeat(const Array<PrimExpr> &repeats,