Lazy deoptimization for comparisons in Turbofan.

src/compiler/js-generic-lowering.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/code-stubs.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph-inl.h"
 #include "src/compiler/js-generic-lowering.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-aux-data-inl.h"
@@ skipping 282 matching lines @@
     result |= CallDescriptor::kNeedsFrameState;
   }
   return result;
 }
 
 
 void JSGenericLowering::ReplaceWithCompareIC(Node* node, Token::Value token,
                                              bool pure) {
   BinaryOpICStub stub(isolate(), Token::ADD);  // TODO(mstarzinger): Hack.
   CodeStubInterfaceDescriptor* d = stub.GetInterfaceDescriptor();
+  bool has_frame_state = OperatorProperties::HasFrameStateInput(node->op());
   CallDescriptor* desc_compare = linkage()->GetStubCallDescriptor(
-      d, 0, CallDescriptor::kPatchableCallSiteWithNop);
+      d, 0, CallDescriptor::kPatchableCallSiteWithNop | FlagsForNode(node));
   Handle<Code> ic = CompareIC::GetUninitialized(isolate(), token);
-  Node* compare;
+  NodeVector inputs(zone());
+  inputs.reserve(node->InputCount() + 1);
+  inputs.push_back(CodeConstant(ic));
+  inputs.push_back(NodeProperties::GetValueInput(node, 0));
+  inputs.push_back(NodeProperties::GetValueInput(node, 1));
+  inputs.push_back(NodeProperties::GetContextInput(node));
   if (pure) {
-    // A pure (strict) comparison doesn't have an effect or control.
-    // But for the graph, we need to add these inputs.
-    compare = graph()->NewNode(common()->Call(desc_compare), CodeConstant(ic),
-                               NodeProperties::GetValueInput(node, 0),
-                               NodeProperties::GetValueInput(node, 1),
-                               NodeProperties::GetContextInput(node),
-                               graph()->start(), graph()->start());
+    DCHECK(!has_frame_state);

[Michael Starzinger, 2014/09/01 23:10:46]

Ouch, this is getting complex, but we can always clean it up later. But could we
preserve the comment about why we add effect and control for pure nodes?

+    inputs.push_back(graph()->start());
+    inputs.push_back(graph()->start());
   } else {
-    compare = graph()->NewNode(common()->Call(desc_compare), CodeConstant(ic),
-                               NodeProperties::GetValueInput(node, 0),
-                               NodeProperties::GetValueInput(node, 1),
-                               NodeProperties::GetContextInput(node),
-                               NodeProperties::GetEffectInput(node),
-                               NodeProperties::GetControlInput(node));
+    DCHECK(has_frame_state == FLAG_turbo_deoptimization);
+    if (FLAG_turbo_deoptimization) {
+      inputs.push_back(NodeProperties::GetFrameStateInput(node));
+    }
+    inputs.push_back(NodeProperties::GetEffectInput(node));
+    inputs.push_back(NodeProperties::GetControlInput(node));
   }
+  Node* compare = graph()->NewNode(common()->Call(desc_compare), inputs.size(),
+                                   &inputs.front());
+
   node->ReplaceInput(0, compare);
   node->ReplaceInput(1, SmiConstant(token));
+
+  if (has_frame_state) {
+    // Remove the frame state from inputs.
+    // TODO(jarin) This should use Node::RemoveInput (which does not exist yet).
+    int dest = NodeProperties::FirstFrameStateIndex(node);
+    for (int i = NodeProperties::PastFrameStateIndex(node);
+         i < node->InputCount(); i++) {
+      node->ReplaceInput(dest, node->InputAt(i));
+      dest++;
+    }
+    node->TrimInputCount(dest);
+  }
+
   ReplaceWithRuntimeCall(node, Runtime::kBooleanize);
 }
 
 
 void JSGenericLowering::ReplaceWithStubCall(Node* node, HydrogenCodeStub* stub,
                                             CallDescriptor::Flags flags) {
   CodeStubInterfaceDescriptor* d = stub->GetInterfaceDescriptor();
   CallDescriptor* desc =
       linkage()->GetStubCallDescriptor(d, 0, flags | FlagsForNode(node));
   Node* stub_code = CodeConstant(stub->GetCode());
@@ skipping 19 matching lines @@
   PatchOperator(node, common()->Call(desc));
 }
 
 
 void JSGenericLowering::ReplaceWithRuntimeCall(Node* node,
                                                Runtime::FunctionId f,
                                                int nargs_override) {
   Operator::Property props = node->op()->properties();
   const Runtime::Function* fun = Runtime::FunctionForId(f);
   int nargs = (nargs_override < 0) ? fun->nargs : nargs_override;
-  CallDescriptor* desc =
-      linkage()->GetRuntimeCallDescriptor(f, nargs, props, FlagsForNode(node));
+  CallDescriptor* desc = linkage()->GetRuntimeCallDescriptor(f, nargs, props);
+  Operator* new_op = common()->Call(desc);

[Michael Starzinger, 2014/09/01 23:10:46]

nit: Please keep this consistent with the other ReplaceWithFoo helpers, let's
either hoist the operator into a local variable everywhere or undo this change
here.

   Node* ref = ExternalConstant(ExternalReference(f, isolate()));
   Node* arity = Int32Constant(nargs);
   if (!centrystub_constant_.is_set()) {
     centrystub_constant_.set(CodeConstant(CEntryStub(isolate(), 1).GetCode()));
   }
   PatchInsertInput(node, 0, centrystub_constant_.get());
   PatchInsertInput(node, nargs + 1, ref);
   PatchInsertInput(node, nargs + 2, arity);
-  PatchOperator(node, common()->Call(desc));
+  PatchOperator(node, new_op);
 }
 
 
 Node* JSGenericLowering::LowerBranch(Node* node) {
   if (!info()->is_typing_enabled()) {
     // TODO(mstarzinger): If typing is enabled then simplified lowering will
     // have inserted the correct ChangeBoolToBit, otherwise we need to perform
     // poor-man's representation inference here and insert manual change.
     Node* test = graph()->NewNode(machine()->WordEqual(), node->InputAt(0),
                                   jsgraph()->TrueConstant());
@@ skipping 154 matching lines @@
 Node* JSGenericLowering::LowerJSCallRuntime(Node* node) {
   Runtime::FunctionId function = OpParameter<Runtime::FunctionId>(node);
   int arity = OperatorProperties::GetValueInputCount(node->op());
   ReplaceWithRuntimeCall(node, function, arity);
   return node;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8