[Refactor] Buffer flatten (#340)

include/tvm/tir/expr.h

@@ -639,6 +639,7 @@ class BufferLoad : public PrimExpr {
  public:
   TVM_DLL explicit BufferLoad(Buffer buffer, Array<PrimExpr> indices, Span span = Span());
   TVM_DEFINE_OBJECT_REF_METHODS(BufferLoad, PrimExpr, BufferLoadNode);
+  TVM_DEFINE_OBJECT_REF_COW_METHOD(BufferLoadNode);
 };
 
 /*!

src/meta_schedule/utils.h

@@ -338,23 +338,8 @@ inline std::ostream& StdCout(int verbose, int setting = 1) {
 
 /**************** String Manipulation ****************/
 
-/*!
- * \brief Find all positions that the specific char occurs in the string
- * \param str The string to be examined
- * \param c The specific char
- * \return A list of integers indicating the occurrence position
- */
-inline std::vector<int> FindCharPos(const String& str, char c) {
-  std::vector<int> result;
-  const char* data = str.data();
-  int n = str.length();
-  for (int i = 0; i < n; ++i) {
-    if (data[i] == c) {
-      result.push_back(i);
-    }
-  }
-  return result;
-}
+using tir::FindCharPos;
+using tir::StartsWith;
 
 /**************** Target Hardware Concurrency ****************/
 

src/tir/schedule/analysis.cc

@@ -54,6 +54,17 @@ bool ContainsVar(const ObjectRef& stmt_or_expr, const std::unordered_set<const V
   return found;
 }
 
+std::unordered_set<const VarNode*> Vars(const ObjectRef& stmt_or_expr) {
+  std::unordered_set<const VarNode*> result;
+  auto f_visit = [&result](const ObjectRef& obj) -> void {
+    if (const auto* var = obj.as<VarNode>()) {
+      result.insert(var);
+    }
+  };
+  PostOrderVisit(stmt_or_expr, f_visit);
+  return result;
+}
+
 bool ValidateBlockBinding(const BlockRealize& realize, const Map<Var, Range>& loop_var_ranges) {
   arith::Analyzer analyzer;
   Array<arith::IterSumExpr> results = arith::DetectIterMap(

src/tir/schedule/analysis.h

@@ -45,6 +45,12 @@ bool ContainsVar(const ObjectRef& stmt_or_expr, const Var& var);
  * \return A boolean indicating if any var in the list is found in stmt/expr
  */
 bool ContainsVar(const ObjectRef& stmt_or_expr, const std::unordered_set<const VarNode*>& var);
+/*!
+ * \brief Collect the variables that appear in the specific Stmt or Expr
+ * \param stmt_or_expr The Stmt or Expr
+ * \return All variables that appear
+ */
+std::unordered_set<const VarNode*> Vars(const ObjectRef& stmt_or_expr);
 
 /******** Verification ********/
 /*!

src/tir/schedule/transform.cc

@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+#include "./utils.h"
+
+namespace tvm {
+namespace tir {
+
+Stmt RealizeInitBlock(const Stmt& init, const Array<IterVar>& iter_vars) {
+  std::vector<PrimExpr> conditions;
+  for (const IterVar& var : iter_vars) {
+    if (var->iter_type == IterVarType::kCommReduce) {
+      conditions.push_back(equal(var->var, var->dom->min));
+    }
+  }
+  int n = conditions.size();
+  // Handle the case where there is no condition
+  if (n == 0) {
+    return init;
+  }
+  // Concate the conditions with logical and (&&)
+  PrimExpr cond = conditions[0];
+  for (int i = 1; i < n; ++i) {
+    cond = logical_and(cond, conditions[i]);
+  }
+  return IfThenElse(cond, init);
+}
+
+}  // namespace tir
+}  // namespace tvm

src/tir/schedule/transform.h

@@ -0,0 +1,40 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+#ifndef TVM_TIR_SCHEDULE_TRANSFORM_H_
+#define TVM_TIR_SCHEDULE_TRANSFORM_H_
+
+#include <tvm/tir/stmt.h>
+
+#include <unordered_set>
+
+namespace tvm {
+namespace tir {
+
+/*!
+ * \brief Transform the init block into actual computation
+ * \param init The init block
+ * \param iter_vars The block variables
+ * \return The actual computation
+ */
+Stmt RealizeInitBlock(const Stmt& init, const Array<IterVar>& iter_vars);
+
+}  // namespace tir
+}  // namespace tvm
+
+#endif  // TVM_TIR_SCHEDULE_TRANSFORM_H_

src/tir/schedule/utils.h

@@ -20,6 +20,7 @@
 #define TVM_TIR_SCHEDULE_SCHEDULE_COMMON_H_
 
 #include <tvm/arith/analyzer.h>
+#include <tvm/arith/int_set.h>
 #include <tvm/arith/iter_affine_map.h>
 #include <tvm/tir/analysis.h>
 #include <tvm/tir/op.h>
@@ -35,6 +36,7 @@
 #include <vector>
 
 #include "./analysis.h"
+#include "./transform.h"
 
 namespace tvm {
 namespace tir {
@@ -455,6 +457,46 @@ static DefaultReducer default_reducers[4] = {
 
 }  // namespace default_reducer
 
+/**************** String ****************/
+
+/*!
+ * \brief Find all positions that the specific char occurs in the string
+ * \param str The string to be examined
+ * \param c The specific char
+ * \return A list of integers indicating the occurrence position
+ */
+inline std::vector<int> FindCharPos(const String& str, char c) {
+  std::vector<int> result;
+  const char* data = str.data();
+  int n = str.length();
+  for (int i = 0; i < n; ++i) {
+    if (data[i] == c) {
+      result.push_back(i);
+    }
+  }
+  return result;
+}
+
+inline bool StartsWith(const String& str, const String& prefix) {
+  int n = prefix.size();
+  if (static_cast<int>(str.size()) < n) {
+    return false;
+  }
+  const char* data = str.data();
+  return std::equal(data, data + n, prefix.data());
+}
+
+inline bool StartsWith(const String& str, const char* prefix) {
+  int n = strlen(prefix);
+  if (static_cast<int>(str.size()) < n) {
+    return false;
+  }
+  const char* data = str.data();
+  return std::equal(data, data + n, prefix);
+}
+
+/**************** Loop extents ****************/
+
 inline int64_t GetLoopIntExtent(const ForNode* loop) {
   const auto* int_extent = loop->extent.as<IntImmNode>();
   return int_extent ? int_extent->value : -1;