Implement context cloning in new compiler.

runtime/vm/flow_graph_compiler_x64.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
@@ skipping 795 matching lines @@
   __ popq(RAX);
   // Chain the new context in RAX to its parent in CTX.
   __ StoreIntoObject(RAX,
                      FieldAddress(RAX, Context::parent_offset()),
                      CTX);
   // Set new context as current context.
   __ movq(CTX, RAX);
 }
 
 
+void FlowGraphCompiler::VisitCloneContext(CloneContextComp* comp) {
+  __ popq(RAX);  // Get context value from stack.
+  __ PushObject(Object::ZoneHandle());  // Make room for the result.
+  __ pushq(RAX);
+  GenerateCallRuntime(comp->node_id(),
+                      comp->token_index(),
+                      kCloneContextRuntimeEntry);
+  __ popq(RAX);  // Remove argument.
+  __ popq(RAX);  // Get result (cloned context).
+}
+
+
 void FlowGraphCompiler::VisitBlocks() {
   for (intptr_t i = 0; i < block_order_.length(); ++i) {
     // Compile the block entry.
     current_block_ = block_order_[i];
     Instruction* instr = current_block()->Accept(this);
     // Compile all successors until an exit, branch, or a block entry.
     while ((instr != NULL) && !instr->IsBlockEntry()) {
       instr = instr->Accept(this);
     }
 
@@ skipping 454 matching lines @@
 void FlowGraphCompiler::FinalizeExceptionHandlers(const Code& code) {
   // We don't compile exception handlers yet.
   code.set_exception_handlers(
       ExceptionHandlers::Handle(ExceptionHandlers::New(0)));
 }
 
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64