Class fields, part 3 (backends)

src/full-codegen/x64/full-codegen-x64.cc

Index: src/full-codegen/x64/full-codegen-x64.cc
diff --git a/src/full-codegen/x64/full-codegen-x64.cc b/src/full-codegen/x64/full-codegen-x64.cc
index 2529b745b6b380202128741adafcbc456f5325bc..351879c1cadd071f9ac7ed9e5419ed7c562c02d7 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -1888,6 +1888,30 @@ void FullCodeGenerator::EmitClassDefineProperties(ClassLiteral* lit) {
     ClassLiteral::Property* property = lit->properties()->at(i);
     Expression* value = property->value();
 
+    if (property->kind() == ClassLiteral::Property::FIELD &&
+        !property->is_static()) {
+      // Non-static properties produced by the parser have as their 'key' an
+      // expression producing their name and as their 'value' a variable which
+      // is refered to by the synthetic initializer function in order to
+      // determine the name during class instantiation. This is necessary
+      // because computed names must only be evaluated once, at class definition
+      // time.
+      // That is, code which looks like `class C { [f()] = 1; }` is desugared
+      // into something like
+      // class C { constructor(){ this.[.class-field-0-name] = 1; } };
+      // let .class-field-0-name = f();
+      // except that the assignment to .class-field-name-0 occurs interleaved
+      // with the rest of the class body; it is performed by the block in which
+      // this comment appears.
+      DCHECK(property->value()->IsVariableProxy());
+      Variable* variable = property->value()->AsVariableProxy()->var();
+      VisitForStackValue(property->key());
+      EmitVariableAssignment(variable, Token::INIT,
+                             FeedbackVectorSlot::Invalid());
+      DropOperands(1);
+      continue;
+    }
+
     if (property->is_static()) {
       PushOperand(Operand(rsp, kPointerSize));  // constructor
     } else {
@@ -1927,8 +1951,11 @@ void FullCodeGenerator::EmitClassDefineProperties(ClassLiteral* lit) {
         break;
 
       case ClassLiteral::Property::FIELD:
-      default:
-        UNREACHABLE();
+        DCHECK(property->is_static());
+        PushOperand(Smi::FromInt(DONT_ENUM));
+        PushOperand(Smi::FromInt(property->NeedsSetFunctionName()));
+        CallRuntimeWithOperands(Runtime::kDefineDataPropertyInLiteral);
+        break;
     }
   }
 }