[mlir] Added the dialect inliner to the SCF dialect

[liufengdb]

Summary

Currently no restrictions are added to the destination regions.

[liufengdb]

Add the terminator op handling

[ftynse]

mlir/lib/Dialect/SCF/SCF.cpp

54

Please use camelCase

[liufengdb]

fix the typo

mlir/lib/Dialect/SCF/SCF.cpp

 #include "mlir/IR/Function.h"
 #include "mlir/IR/Matchers.h"
 #include "mlir/IR/Module.h"
 #include "mlir/IR/OpImplementation.h"
 #include "mlir/IR/PatternMatch.h"
 #include "mlir/IR/StandardTypes.h"
 #include "mlir/IR/Value.h"
 #include "mlir/Support/MathExtras.h"
+#include "mlir/Transforms/InliningUtils.h"
 
 using namespace mlir;
 using namespace mlir::scf;
 
 //===----------------------------------------------------------------------===//
+// SCFDialect Dialect Interfaces
+//===----------------------------------------------------------------------===//
+
+namespace {
+struct SCFInlinerInterface : public DialectInlinerInterface {
+  using DialectInlinerInterface::DialectInlinerInterface;
+  // We don't have any special restrictions on what can be inlined into
+  // destination regions (e.g. while/conditional bodies). Always allow it.
+  bool isLegalToInline(Region *dest, Region *src,
+                       BlockAndValueMapping &valueMapping) const final {
+    return true;
+  }
+  // Operations in scf dialect are always legal to inline since they are
+  // pure.
+  bool isLegalToInline(Operation *, Region *,
+                       BlockAndValueMapping &) const final {
+    return true;
+  }
+  // Handle the given inlined terminator by replacing it with a new operation
+  // as necessary. Required when the region has only one block.
+  void handleTerminator(Operation *op,
+                        ArrayRef<Value> valuesToRepl) const final {
+    auto retValOp = dyn_cast<YieldOp>(op);
+    if (!retValOp)
+      return;
+
+    for (auto ret_value : llvm::zip(valuesToRepl, retValOp.getOperands())) {
+      std::get<0>(ret_value).replaceAllUsesWith(std::get<1>(ret_value));
+    }
+  }
+};
+} // end anonymous namespace
+
+//===----------------------------------------------------------------------===//
 // SCFDialect
 //===----------------------------------------------------------------------===//
 
 SCFDialect::SCFDialect(MLIRContext *context)
     : Dialect(getDialectNamespace(), context) {
   addOperations<
 #define GET_OP_LIST
 #include "mlir/Dialect/SCF/SCFOps.cpp.inc"
       >();
+  addInterfaces<SCFInlinerInterface>();
 }
 
 /// Default callback for IfOp builders. Inserts a yield without arguments.
 void mlir::scf::buildTerminatedBody(OpBuilder &builder, Location loc) {
   builder.create<scf::YieldOp>(loc);
 }
 
 //===----------------------------------------------------------------------===//