Class fields, part 3 (backends)

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

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/full-codegen/full-codegen.h"
 #include "src/ast/compile-time-value.h"
 #include "src/ast/scopes.h"
 #include "src/code-factory.h"
@@ skipping 1870 matching lines @@
   __ bind(&done);
   context()->Plug(rax);
 }
 
 
 void FullCodeGenerator::EmitClassDefineProperties(ClassLiteral* lit) {
   for (int i = 0; i < lit->properties()->length(); i++) {
     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 {
       PushOperand(Operand(rsp, 0));  // prototype
     }
     EmitPropertyKey(property, lit->GetIdForProperty(i));
 
     // The static prototype property is read only. We handle the non computed
     // property name case in the parser. Since this is the only case where we
     // need to check for an own read only property we special case this so we do
@@ skipping 19 matching lines @@
         PushOperand(Smi::FromInt(DONT_ENUM));
         CallRuntimeWithOperands(Runtime::kDefineGetterPropertyUnchecked);
         break;
 
       case ClassLiteral::Property::SETTER:
         PushOperand(Smi::FromInt(DONT_ENUM));
         CallRuntimeWithOperands(Runtime::kDefineSetterPropertyUnchecked);
         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;
     }
   }
 }
 
 
 void FullCodeGenerator::EmitBinaryOp(BinaryOperation* expr, Token::Value op) {
   PopOperand(rdx);
   Handle<Code> code = CodeFactory::BinaryOpIC(isolate(), op).code();
   JumpPatchSite patch_site(masm_);    // unbound, signals no inlined smi code.
   CallIC(code, expr->BinaryOperationFeedbackId());
@@ skipping 1676 matching lines @@
   DCHECK_EQ(
       isolate->builtins()->OnStackReplacement()->entry(),
       Assembler::target_address_at(call_target_address, unoptimized_code));
   return ON_STACK_REPLACEMENT;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64