[Unity][Layout] Add layout transformation analysis for PrimFunc (#14066)

* [Layout] Add layout transformation analysis for PrimFunc.

This change adds a PrimFunc level analysis to suggest layout transformations to block and buffers in the PrimFunc based on the layout transformations to PrimFunc outputs.

* Add support for multiple blocks such as split op.

* Add negative tests and increase coverage.

* fix warning message

* fix lint

* remove unused header

* Address comments.
Moved some utility functions to support/array.h
improve doc

* fix deprecation warn T.var("int64") to T.int64()

* address comments

include/tvm/relax/analysis.h

@@ -403,6 +403,19 @@ TVM_DLL bool HasReshapePattern(const tir::PrimFunc& func);
  */
 TVM_DLL bool WellFormed(IRModule m, bool check_struct_info = true);
 
+/*!
+ * \brief Using the layout transforms on the outputs, suggest layout transformation on the blocks
+ * and buffers for the PrimFunc.
+ *
+ * \param fn The PrimFunc to be analyzed.
+ * \param write_buffer_transformations Array of IndexMap transformations on PrimFunc outputs.
+ * \return Suggested transforms per block in `fn`. For each block the returned value is a map
+ * from the object (block or buffer) to it's index map transformation.
+ */
+
+TVM_DLL Map<tir::Block, Map<ObjectRef, tir::IndexMap>> SuggestLayoutTransforms(
+    const Function& fn, Array<tir::IndexMap> write_buffer_transformations);
+
 }  // namespace relax
 }  // namespace tvm
 

python/tvm/relax/analysis/analysis.py

@@ -21,14 +21,15 @@
 configuring the passes and scripting them in Python.
 """
 
-from typing import Dict, List
+from typing import Dict, List, Union, Callable
 from enum import IntEnum
 
 from tvm import tir
 from tvm import IRModule
 from tvm.relax.ty import Type
 from tvm.relax.struct_info import StructInfo, FuncStructInfo
 from tvm.relax.expr import DataflowBlock, Var, Expr, Function, Call, Binding
+from tvm.tir import IndexMap, PrimFunc, Block, Buffer
 from . import _ffi_api
 
 
@@ -289,3 +290,32 @@ def well_formed(mod: IRModule, check_struct_info: bool = True) -> bool:
     will be well tested and will not be blocked by not having structure info.
     """
     return _ffi_api.well_formed(mod, check_struct_info)  # type: ignore
+
+
+def suggest_layout_transforms(
+    func: PrimFunc, write_buffer_transforms: List[Union[IndexMap, Callable]]
+) -> Dict[Block, Dict[Union[Block, Buffer], IndexMap]]:
+    """Suggest Layout transformations of blocks and buffers in a PrimFunc.
+
+    Parameters
+    ----------
+    func: PrimFunc
+        PrimFunc on which analysis will be performed and transformations suggested.
+
+    write_buffer_transforms: List[Union[IndexMap, Callable]
+        List of layout transformations on the output buffers. The number of layout
+        transformations must match the number of outputs of the PrimFunc.
+
+    Returns
+    -------
+    ret: Dict[Block, Dict[Union[Block, Buffer], IndexMap]]
+         Suggested transforms per block in `func`. For each block the returned value is a map
+         from the object (block or buffer) to it's index map transformation.
+    """
+    write_buffer_index_maps = []
+    for transform in write_buffer_transforms:
+        if callable(transform):
+            transform = IndexMap.from_func(transform)
+        assert isinstance(transform, IndexMap)
+        write_buffer_index_maps.append(transform)
+    return _ffi_api.suggest_layout_transforms(func, write_buffer_index_maps)  # type: ignore