[turbofan] Introduce CheckString simplified operator.

src/compiler/effect-control-linearizer.cc

 // Copyright 2015 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/effect-control-linearizer.h"
 
 #include "src/code-factory.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/linkage.h"
@@ skipping 607 matching lines @@
       break;
     case IrOpcode::kTruncateTaggedToFloat64:
       state = LowerTruncateTaggedToFloat64(node, *effect, *control);
       break;
     case IrOpcode::kCheckBounds:
       state = LowerCheckBounds(node, frame_state, *effect, *control);
       break;
     case IrOpcode::kCheckNumber:
       state = LowerCheckNumber(node, frame_state, *effect, *control);
       break;
+    case IrOpcode::kCheckString:
+      state = LowerCheckString(node, frame_state, *effect, *control);
+      break;
     case IrOpcode::kCheckIf:
       state = LowerCheckIf(node, frame_state, *effect, *control);
       break;
     case IrOpcode::kCheckTaggedPointer:
       state = LowerCheckTaggedPointer(node, frame_state, *effect, *control);
       break;
     case IrOpcode::kCheckTaggedSigned:
       state = LowerCheckTaggedSigned(node, frame_state, *effect, *control);
       break;
     case IrOpcode::kCheckedInt32Add:
@@ skipping 399 matching lines @@
         frame_state, efalse0, if_false0);
   }
 
   control = graph()->NewNode(common()->Merge(2), if_true0, if_false0);
   effect = graph()->NewNode(common()->EffectPhi(2), etrue0, efalse0, control);
 
   return ValueEffectControl(value, effect, control);
 }
 
 EffectControlLinearizer::ValueEffectControl
+EffectControlLinearizer::LowerCheckString(Node* node, Node* frame_state,
+                                          Node* effect, Node* control) {
+  Node* value = node->InputAt(0);
+
+  Node* check0 = ObjectIsSmi(value);
+  control = effect =
+      graph()->NewNode(common()->DeoptimizeIf(DeoptimizeReason::kSmi), check0,
+                       frame_state, effect, control);
+
+  Node* value_map = effect = graph()->NewNode(
+      simplified()->LoadField(AccessBuilder::ForMap()), value, effect, control);
+  Node* value_instance_type = effect = graph()->NewNode(
+      simplified()->LoadField(AccessBuilder::ForMapInstanceType()), value_map,
+      effect, control);
+
+  Node* check1 =
+      graph()->NewNode(machine()->Uint32LessThan(), value_instance_type,
+                       jsgraph()->Uint32Constant(FIRST_NONSTRING_TYPE));
+  control = effect = graph()->NewNode(
+      common()->DeoptimizeUnless(DeoptimizeReason::kWrongInstanceType), check1,
+      frame_state, effect, control);
+
+  return ValueEffectControl(value, effect, control);
+}
+
+EffectControlLinearizer::ValueEffectControl
 EffectControlLinearizer::LowerCheckIf(Node* node, Node* frame_state,
                                       Node* effect, Node* control) {
   Node* value = node->InputAt(0);
 
   control = effect =
       graph()->NewNode(common()->DeoptimizeUnless(DeoptimizeReason::kNoReason),
                        value, frame_state, effect, control);
 
   return ValueEffectControl(value, effect, control);
 }
@@ skipping 1142 matching lines @@
         isolate(), graph()->zone(), callable.descriptor(), 0, flags,
         Operator::kNoThrow);
     to_number_operator_.set(common()->Call(desc));
   }
   return to_number_operator_.get();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8