[turbofan] Implement OSR for outer loops.

src/compiler/osr.cc

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/compiler.h"
+#include "src/compiler/common-operator.h"
+#include "src/compiler/frame.h"
+#include "src/compiler/graph.h"
+#include "src/compiler/node.h"
+#include "src/compiler/osr.h"
+#include "src/scopes.h"
+
+namespace v8 {
+namespace internal {
+namespace compiler {
+
+OsrHelper::OsrHelper(CompilationInfo* info)
+    : parameter_count_(info->scope()->num_parameters()),
+      stack_slot_count_(info->scope()->num_stack_slots()) {}
+
+
+void OsrHelper::Deconstruct(Graph* graph, CommonOperatorBuilder* common,
+                            Zone* tmp_zone) {
+  NodeDeque queue(tmp_zone);
+  NodeMarker<bool> marker(graph, 2);
+  queue.push_back(graph->end());
+  marker.Set(graph->end(), true);
+
+  while (!queue.empty()) {
+    Node* node = queue.front();
+    queue.pop_front();
+
+    // Rewrite OSR-related nodes.
+    switch (node->opcode()) {
+      case IrOpcode::kOsrNormalEntry:
+        node->ReplaceUses(graph->NewNode(common->Dead()));
+        break;
+      case IrOpcode::kOsrLoopEntry:
+        node->ReplaceUses(graph->start());
+        break;
+      default:
+        break;
+    }
+    for (Node* const input : node->inputs()) {
+      if (!marker.Get(input)) {
+        marker.Set(input, true);
+        queue.push_back(input);
+      }
+    }
+  }
+}
+
+
+void OsrHelper::SetupFrame(Frame* frame) {
+  // The optimized frame will subsume the unoptimized frame. Do so by reserving
+  // the first spill slots.
+  frame->ReserveSpillSlots(UnoptimizedFrameSlots());
+}
+
+
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8