Scaffolding for convertToCFG pass that replaces all instances of ML functions with equivalent CFG functions. Traverses module MLIR, generates CFG functions (empty for now) and removes ML functions. Adds Transforms library and tests.
PiperOrigin-RevId: 205848367
diff --git a/lib/IR/Builders.cpp b/lib/IR/Builders.cpp
index dc5b8e2..d5b85cc 100644
--- a/lib/IR/Builders.cpp
+++ b/lib/IR/Builders.cpp
@@ -141,7 +141,19 @@
}
//===----------------------------------------------------------------------===//
-// Statements
+// CFG function elements.
+//===----------------------------------------------------------------------===//
+
+// Basic block.
+BasicBlock *CFGFuncBuilder::createBlock() {
+ BasicBlock *b = new BasicBlock();
+ function->push_back(b);
+ setInsertionPoint(b);
+ return b;
+}
+
+//===----------------------------------------------------------------------===//
+// Statements.
//===----------------------------------------------------------------------===//
ForStmt *MLFuncBuilder::createFor(AffineConstantExpr *lowerBound,
@@ -149,7 +161,7 @@
AffineConstantExpr *step) {
if (!step)
step = getConstantExpr(1);
- auto stmt = new ForStmt(lowerBound, upperBound, step);
+ auto *stmt = new ForStmt(lowerBound, upperBound, step);
block->getStatements().push_back(stmt);
return stmt;
}
diff --git a/lib/IR/Statement.cpp b/lib/IR/Statement.cpp
index dd73a87..b469482 100644
--- a/lib/IR/Statement.cpp
+++ b/lib/IR/Statement.cpp
@@ -30,16 +30,16 @@
}
/// Destroy this statement or one of its subclasses.
-void Statement::destroy(Statement *stmt) {
- switch (stmt->getKind()) {
+void Statement::destroy() {
+ switch (this->getKind()) {
case Kind::Operation:
- delete cast<OperationStmt>(stmt);
+ delete cast<OperationStmt>(this);
break;
case Kind::For:
- delete cast<ForStmt>(stmt);
+ delete cast<ForStmt>(this);
break;
case Kind::If:
- delete cast<IfStmt>(stmt);
+ delete cast<IfStmt>(this);
break;
}
}
@@ -102,7 +102,6 @@
//===----------------------------------------------------------------------===//
IfStmt::~IfStmt() {
- // TODO: correctly delete StmtBlocks under then and else clauses
delete thenClause;
if (elseClause != nullptr)
delete elseClause;
diff --git a/lib/Transforms/ConvertToCFG.cpp b/lib/Transforms/ConvertToCFG.cpp
new file mode 100644
index 0000000..0a98e2b
--- /dev/null
+++ b/lib/Transforms/ConvertToCFG.cpp
@@ -0,0 +1,166 @@
+//===- ConvertToCFG.cpp - ML function to CFG function converstion ---------===//
+//
+// Copyright 2019 The MLIR Authors.
+//
+// Licensed 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.
+// =============================================================================
+//
+// This file implements APIs to convert ML functions into CFG functions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Transforms/ConvertToCFG.h"
+#include "mlir/IR/Builders.h"
+#include "mlir/IR/CFGFunction.h"
+#include "mlir/IR/MLFunction.h"
+#include "mlir/IR/Module.h"
+#include "llvm/ADT/DenseSet.h"
+using namespace mlir;
+
+//===----------------------------------------------------------------------===//
+// ML function converter
+//===----------------------------------------------------------------------===//
+
+namespace {
+// Generates CFG function equivalent to the given ML function.
+class FunctionConverter {
+public:
+ FunctionConverter(CFGFunction *cfgFunc)
+ : cfgFunc(cfgFunc), builder(cfgFunc) {}
+ CFGFunction *convert(const MLFunction *mlFunc);
+
+private:
+ CFGFunction *cfgFunc;
+ CFGFuncBuilder builder;
+};
+} // namespace
+
+CFGFunction *FunctionConverter::convert(const MLFunction *mlFunc) {
+ builder.createBlock();
+
+ // Creates return instruction with no operands.
+ // TODO: convert return operands.
+ builder.createReturnInst({});
+
+ // TODO: convert ML function body.
+
+ return cfgFunc;
+}
+
+//===----------------------------------------------------------------------===//
+// Module converter
+//===----------------------------------------------------------------------===//
+namespace {
+// ModuleConverter class does CFG conversion for the whole module.
+class ModuleConverter {
+public:
+ explicit ModuleConverter(Module *module) : module(module) {}
+ void run();
+
+private:
+ // Generates CFG functions for all ML functions in the module.
+ void convertMLFunctions();
+ // Generates CFG function for the given ML function.
+ CFGFunction *convert(const MLFunction *mlFunc);
+ // Replaces all ML function references in the module
+ // with references to the generated CFG functions.
+ void replaceReferences();
+ // Replaces function references in the given function.
+ void replaceReferences(CFGFunction *cfgFunc);
+ void replaceReferences(MLFunction *mlFunc);
+ // Removes all ML funtions from the module.
+ void removeMLFunctions();
+
+ // Map from ML functions to generated CFG functions.
+ llvm::DenseMap<const MLFunction *, CFGFunction *> generatedFuncs;
+ Module *module;
+};
+} // end anonymous namespace
+
+// Iterates over all functions in the module generating CFG functions
+// equivalent to ML functions and replacing references to ML functions
+// with references to the generated ML functions.
+void ModuleConverter::run() {
+ convertMLFunctions();
+ replaceReferences();
+}
+
+void ModuleConverter::convertMLFunctions() {
+ for (Function *fn : module->functionList) {
+ if (auto mlFunc = dyn_cast<MLFunction>(fn))
+ generatedFuncs[mlFunc] = convert(mlFunc);
+ }
+}
+
+// Creates CFG function equivalent to the given ML function.
+CFGFunction *ModuleConverter::convert(const MLFunction *mlFunc) {
+ // TODO: ensure that CFG function name is unique.
+ CFGFunction *cfgFunc =
+ new CFGFunction(mlFunc->getName() + "_cfg", mlFunc->getType());
+ module->functionList.push_back(cfgFunc);
+
+ // Generates the body of the CFG function.
+ return FunctionConverter(cfgFunc).convert(mlFunc);
+}
+
+void ModuleConverter::replaceReferences() {
+ for (Function *fn : module->functionList) {
+ switch (fn->getKind()) {
+ case Function::Kind::CFGFunc:
+ replaceReferences(cast<CFGFunction>(fn));
+ break;
+ case Function::Kind::MLFunc:
+ replaceReferences(cast<MLFunction>(fn));
+ break;
+ case Function::Kind::ExtFunc:
+ // nothing to do for external functions
+ break;
+ }
+ }
+}
+
+void ModuleConverter::replaceReferences(CFGFunction *func) {
+ // TODO: NOP for now since function attributes are not yet implemented.
+}
+
+void ModuleConverter::replaceReferences(MLFunction *func) {
+ // TODO: NOP for now since function attributes are not yet implemented.
+}
+
+// Removes all ML functions from the module.
+void ModuleConverter::removeMLFunctions() {
+ std::vector<Function *> &fnList = module->functionList;
+
+ // Delete ML functions and its data.
+ for (auto &fn : fnList) {
+ if (auto mlFunc = dyn_cast<MLFunction>(fn)) {
+ delete mlFunc;
+ fn = nullptr;
+ }
+ }
+
+ // Remove ML functions from the function list.
+ fnList.erase(std::remove_if(fnList.begin(), fnList.end(),
+ [](Function *fn) { return !fn; }),
+ fnList.end());
+}
+
+//===----------------------------------------------------------------------===//
+// Entry point method
+//===----------------------------------------------------------------------===//
+
+void mlir::convertToCFG(Module *module) {
+ ModuleConverter moduleConverter(module);
+ moduleConverter.run();
+ module->verify();
+}