[turbofan] Pass NoContextConstant to stubs that don't need a context.

The generic implementations for typeof, strict equality and ToBoolean
don't need a context, so we can just pass the NoContextConstant (which
is Smi zero) instead, to reduce the live ranges for the context.

R=mvstanton@chromium.org

Review-Url: https://codereview.chromium.org/2400633002
Cr-Commit-Position: refs/heads/master@{#40027}

src/compiler/js-generic-lowering.cc

@@ -116,6 +116,8 @@ void JSGenericLowering::ReplaceWithRuntimeCall(Node* node,
 }
 
 void JSGenericLowering::LowerJSStrictEqual(Node* node) {
+  // The === operator doesn't need the current context.
+  NodeProperties::ReplaceContextInput(node, jsgraph()->NoContextConstant());
   Callable callable = CodeFactory::StrictEqual(isolate());
   node->RemoveInput(4);  // control
   ReplaceWithStubCall(node, callable, CallDescriptor::kNoFlags,
@@ -123,6 +125,8 @@ void JSGenericLowering::LowerJSStrictEqual(Node* node) {
 }
 
 void JSGenericLowering::LowerJSStrictNotEqual(Node* node) {
+  // The !== operator doesn't need the current context.
+  NodeProperties::ReplaceContextInput(node, jsgraph()->NoContextConstant());
   Callable callable = CodeFactory::StrictNotEqual(isolate());
   node->RemoveInput(4);  // control
   ReplaceWithStubCall(node, callable, CallDescriptor::kNoFlags,
@@ -130,6 +134,8 @@ void JSGenericLowering::LowerJSStrictNotEqual(Node* node) {
 }
 
 void JSGenericLowering::LowerJSToBoolean(Node* node) {
+  // The ToBoolean conversion doesn't need the current context.
+  NodeProperties::ReplaceContextInput(node, jsgraph()->NoContextConstant());
   Callable callable = CodeFactory::ToBoolean(isolate());
   node->AppendInput(zone(), graph()->start());
   ReplaceWithStubCall(node, callable, CallDescriptor::kNoAllocate,
@@ -137,6 +143,8 @@ void JSGenericLowering::LowerJSToBoolean(Node* node) {
 }
 
 void JSGenericLowering::LowerJSTypeOf(Node* node) {
+  // The typeof operator doesn't need the current context.
+  NodeProperties::ReplaceContextInput(node, jsgraph()->NoContextConstant());
   Callable callable = CodeFactory::Typeof(isolate());
   node->AppendInput(zone(), graph()->start());
   ReplaceWithStubCall(node, callable, CallDescriptor::kNoAllocate,