[TIR] Add schedule primitive ReIndex

Author: vinx13

include/tvm/tir/schedule/schedule.h

@@ -364,6 +364,19 @@ class ScheduleNode : public runtime::Object {
    */
   virtual BlockRV CacheWrite(const BlockRV& block_rv, int write_buffer_index,
                              const String& storage_scope) = 0;
+  /*!
+   * \brief Create a block that read/write a buffer region into a read/write cache with reindexing.
+   * The layout of the cache will be the same as by the iterators of the block that reads/writes the
+   * buffer. It requires:
+   * 1) There is only one block who reads/writes the target buffer
+   * 2) There is only one buffer load/store of this buffer in the block
+   * \param block_rv The block operates on the target buffer.
+   * \param buffer_index The index of the buffer in block's read or write region.
+   * \param buffer_index_type The type of the buffer index, kRead or kWrite.
+   * \return The reindex stage block.
+   */
+  virtual BlockRV ReIndex(const BlockRV& block_rv, int buffer_index,
+                          BufferIndexType buffer_index_type) = 0;
   /******** Schedule: Compute location ********/
   /*!
    * \brief Move a producer block under the specific loop, and regenerate the

python/tvm/tir/schedule/schedule.py

@@ -1056,6 +1056,79 @@ def after_cache_write(a: T.handle, b: T.handle) -> None:
             self, block, write_buffer_index, storage_scope
         )
 
+    @type_checked
+    def reindex(self, block: BlockRV, buffer_index: int, buffer_index_type: str) -> BlockRV:
+        """Create a block that read/write a buffer region into a read/write cache with reindexing.
+        The layout of the cache will be the same as by the iterators of the block that reads/writes
+        the buffer. It requires:
+        1) There is only one block who reads/writes the target buffer
+        2) There is only one buffer load/store of this buffer in the block
+
+        Parameters
+        ----------
+        block: BlockRV
+            The block that accesses the target buffer
+        buffer_index: int
+            The index of the buffer in block's read or write region
+        buffer_index_type : str
+            Type of the buffer index, "read" or "write"
+
+        Returns
+        -------
+        reindex_block : BlockRV
+            The block of the reindex stage
+
+        Examples
+        --------
+
+        Before transform_layout, in TensorIR, the IR is:
+
+        .. code-block:: python
+
+            @T.prim_func
+            def before_reindex(
+                A: T.Buffer[(128, 128), "float32"],
+                B: T.Buffer[(128, 128), "float32"]
+            ) -> None:
+                for i, j in T.grid(128, 128):
+                    with T.block("B"):
+                        vi, vj = T.axis.remap("SS", [i, j])
+                        B[vi, vj] = A[vj, vi] * 2.0
+
+        Create the schedule and do transform_layout:
+
+        .. code-block:: python
+
+            sch = tir.Schedule(before_reindex)
+            block = sch.get_block("B")
+            sch.reindex(block, 0, "read)
+
+        After applying reindex, the IR becomes:
+
+        .. code-block:: python
+
+            @T.prim_func
+            def after_reindex(
+                A: T.Buffer[(128, 128), "float32"],
+                B: T.Buffer[(128, 128), "float32"]
+            ) -> None:
+                A_reindex = T.alloc_buffer((128, 128), "float32")
+                for i, j in T.grid(128, 128):
+                    with T.block("A_reindex"):
+                        vi, vj = T.axis.remap("SS", [i, j])
+                        A_reindex[vi, vj] = A[vj, vi]
+                for i, j in T.grid(128, 128):
+                    with T.block("B"):
+                        vi, vj = T.axis.remap("SS", [i, j])
+                        B[vi, vj] = A_reindex[vi, vj] * 2.0
+
+        """
+        assert buffer_index_type in ["read", "write"], "Invalid buffer_index_type"
+        buffer_index_type_enum = 0 if buffer_index_type == "read" else 1
+        return _ffi_api.ScheduleReIndex(  # type: ignore # pylint: disable=no-member
+            self, block, buffer_index, buffer_index_type_enum
+        )
+
     ########## Schedule: Compute location ##########
 
     @type_checked

src/tir/schedule/concrete_schedule.cc

@@ -511,6 +511,16 @@ BlockRV ConcreteScheduleNode::CacheWrite(const BlockRV& block_rv, int write_buff
   return CreateRV<BlockRV>(result);
 }
 
+BlockRV ConcreteScheduleNode::ReIndex(const BlockRV& block_rv, int buffer_index,
+                                      BufferIndexType buffer_index_type) {
+  StmtSRef result{nullptr};
+  TVM_TIR_SCHEDULE_BEGIN();
+  result = tir::ReIndex(state_, this->GetSRef(block_rv), buffer_index, buffer_index_type);
+  TVM_TIR_SCHEDULE_END("reindex", this->error_render_level_);
+  this->state_->DebugVerify();
+  return CreateRV<BlockRV>(result);
+}
+
 /******** Schedule: Compute location ********/
 
 void ConcreteScheduleNode::ComputeAt(const BlockRV& block_rv, const LoopRV& loop_rv,

src/tir/schedule/concrete_schedule.h

@@ -109,6 +109,8 @@ class ConcreteScheduleNode : public ScheduleNode {
                     const String& storage_scope) override;
   BlockRV CacheWrite(const BlockRV& block_rv, int write_buffer_index,
                      const String& storage_scope) override;
+  BlockRV ReIndex(const BlockRV& block_rv, int buffer_index,
+                  BufferIndexType buffer_index_type) override;
   /******** Schedule: Compute location ********/
   void ComputeAt(const BlockRV& block_rv, const LoopRV& loop_rv, bool preserve_unit_loops) override;
   void ReverseComputeAt(const BlockRV& block_rv, const LoopRV& loop_rv,

src/tir/schedule/primitive.h

@@ -253,6 +253,21 @@ TVM_DLL StmtSRef CacheRead(ScheduleState self, const StmtSRef& block_sref, int r
  */
 TVM_DLL StmtSRef CacheWrite(ScheduleState self, const StmtSRef& block_sref, int write_buffer_index,
                             const String& storage_scope);
+/*!
+ *!
+ * \brief Create a block that read/write a buffer region into a read/write cache with reindexing.
+ * The layout of the cache will be the same as by the iterators of the block that reads/writes the
+ * buffer. It requires:
+ * 1) There is only one block who reads/writes the target buffer
+ * 2) There is only one buffer load/store of this buffer in the block
+ * \param self The state of the schedule
+ * \param block_rv The block operates on the target buffer.
+ * \param buffer_index The index of the buffer in block's read or write region.
+ * \param buffer_index_type The type of the buffer index, kRead or kWrite.
+ * \return The reindex stage block.
+ */
+TVM_DLL StmtSRef ReIndex(ScheduleState self, const StmtSRef& block_sref, int buffer_index,
+                         BufferIndexType buffer_index_type);
 /******** Schedule: Compute location ********/
 /*!
  * \brief Move a producer block under the specific loop, and regenerate the