[turbofan] Implement OSR for outer loops.

src/compiler/graph-builder.cc

 // Copyright 2013 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/graph-builder.h"
 
 #include "src/bit-vector.h"
 #include "src/compiler.h"
 #include "src/compiler/graph-visualizer.h"
 #include "src/compiler/node.h"
@@ skipping 150 matching lines @@
   UpdateEffectDependency(effect);
 
   // Introduce Phi nodes for values that have differing input at merge points,
   // potentially extending an existing Phi node if possible.
   for (int i = 0; i < static_cast<int>(values_.size()); ++i) {
     values_[i] = builder_->MergeValue(values_[i], other->values_[i], control);
   }
 }
 
 
-void StructuredGraphBuilder::Environment::PrepareForLoop(BitVector* assigned) {
-  Node* control = GetControlDependency();
+void StructuredGraphBuilder::Environment::PrepareForLoop(BitVector* assigned,
+                                                         bool is_osr) {
   int size = static_cast<int>(values()->size());
-  if (assigned == NULL) {
+
+  Node* control = builder_->NewLoop();
+  if (assigned == nullptr) {
     // Assume that everything is updated in the loop.
     for (int i = 0; i < size; ++i) {
       Node* phi = builder_->NewPhi(1, values()->at(i), control);
       values()->at(i) = phi;
     }
   } else {
     // Only build phis for those locals assigned in this loop.
     for (int i = 0; i < size; ++i) {
       if (i < assigned->length() && !assigned->Contains(i)) continue;
       Node* phi = builder_->NewPhi(1, values()->at(i), control);
       values()->at(i) = phi;
     }
   }
   Node* effect = builder_->NewEffectPhi(1, GetEffectDependency(), control);
   UpdateEffectDependency(effect);
+
+  if (is_osr) {
+    // Merge OSR values as inputs to the phis of the loop.
+    Graph* graph = builder_->graph();
+    Node* osr_loop_entry = builder_->graph()->NewNode(
+        builder_->common()->OsrLoopEntry(), graph->start(), graph->start());
+
+    builder_->MergeControl(control, osr_loop_entry);
+    builder_->MergeEffect(effect, osr_loop_entry, control);
+
+    for (int i = 0; i < size; ++i) {
+      Node* val = values()->at(i);
+      // TODO(titzer): use IrOpcode::IsConstant() or similar.
+      if (val->opcode() == IrOpcode::kNumberConstant ||
+          val->opcode() == IrOpcode::kInt32Constant ||
+          val->opcode() == IrOpcode::kInt64Constant ||
+          val->opcode() == IrOpcode::kFloat64Constant ||
+          val->opcode() == IrOpcode::kHeapConstant)
+        continue;
+      Node* osr_value =
+          graph->NewNode(builder_->common()->OsrValue(i), osr_loop_entry);
+      values()->at(i) = builder_->MergeValue(val, osr_value, control);
+    }
+  }
 }
 
 
 Node* StructuredGraphBuilder::NewPhi(int count, Node* input, Node* control) {
   const Operator* phi_op = common()->Phi(kMachAnyTagged, count);
   Node** buffer = EnsureInputBufferSize(count + 1);
   MemsetPointer(buffer, input, count);
   buffer[count] = control;
   return graph()->NewNode(phi_op, count + 1, buffer, true);
 }
@@ skipping 70 matching lines @@
   if (!dead_control_.is_set()) {
     Node* dead_node = graph()->NewNode(common_->Dead());
     dead_control_.set(dead_node);
     return dead_node;
   }
   return dead_control_.get();
 }
 }
 }
 }  // namespace v8::internal::compiler