VM: Implement closure calls as instance calls.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 34916)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -5414,31 +5414,53 @@
 
 
 LocationSummary* ClosureCallInstr::MakeLocationSummary(bool opt) const {
-  const intptr_t kNumInputs = 0;
-  const intptr_t kNumTemps = 1;
-  LocationSummary* result =
-      new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kCall);
-  result->set_out(0, Location::RegisterLocation(RAX));
-  result->set_temp(0, Location::RegisterLocation(R10));  // Arg. descriptor.
-  return result;
+  return MakeCallSummary();
 }
 
 
 void ClosureCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  // The arguments to the stub include the closure, as does the arguments
-  // descriptor.
-  Register temp_reg = locs()->temp(0).reg();
-  int argument_count = ArgumentCount();
+  // Load closure object (first argument) in R13.
+  intptr_t argument_count = ArgumentCount();
+  __ movq(R13, Address(RSP, (argument_count - 1) * kWordSize));
+
+  // Arguments descriptor is expected in R10.
   const Array& arguments_descriptor =
       Array::ZoneHandle(ArgumentsDescriptor::New(argument_count,
                                                  argument_names()));
-  __ LoadObject(temp_reg, arguments_descriptor, PP);
-  ASSERT(temp_reg == R10);
-  compiler->GenerateDartCall(deopt_id(),
-                             token_pos(),
-                             &StubCode::CallClosureFunctionLabel(),
-                             PcDescriptors::kClosureCall,
-                             locs());
+  __ LoadObject(R10, arguments_descriptor, PP);
+
+  // Load the actual closure function.
+  __ movq(RAX, FieldAddress(R13, Closure::function_offset()));
+
+  // Load closure context in CTX; note that CTX has already been preserved.
+  __ movq(CTX, FieldAddress(R13, Closure::context_offset()));
+
+  // Load closure function code in RAX.
+  __ movq(RCX, FieldAddress(RAX, Function::code_offset()));
+
+  // RAX: Function.
+  // R10: Arguments descriptor array.
+  // RBX: Smi 0 (no IC data; the lazy-compile stub expects a GC-safe value).
+  __ xorq(RBX, RBX);
+  __ movq(RCX, FieldAddress(RCX, Code::instructions_offset()));
+  __ addq(RCX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
+  __ call(RCX);
+  compiler->AddCurrentDescriptor(PcDescriptors::kClosureCall,
+                                 deopt_id(),
+                                 token_pos());
+  compiler->RecordSafepoint(locs());
+  // Marks either the continuation point in unoptimized code or the
+  // deoptimization point in optimized code, after call.
+  const intptr_t deopt_id_after = Isolate::ToDeoptAfter(deopt_id());
+  if (compiler->is_optimizing()) {
+    compiler->AddDeoptIndexAtCall(deopt_id_after, token_pos());
+  } else {
+    // Add deoptimization continuation point after the call and before the
+    // arguments are removed.
+    compiler->AddCurrentDescriptor(PcDescriptors::kDeopt,
+                                   deopt_id_after,
+                                   token_pos());
+  }
   __ Drop(argument_count);
 }