Don't load arguments descriptor for optimized static calls.

runtime/vm/flow_graph_compiler_x64.cc

 // Copyright (c) 2013, 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 1039 matching lines @@
 
   const int num_fixed_params = function.num_fixed_parameters();
   const int num_copied_params = parsed_function().num_copied_params();
   const int num_locals = parsed_function().num_stack_locals();
 
   // We check the number of passed arguments when we have to copy them due to
   // the presence of optional parameters.
   // No such checking code is generated if only fixed parameters are declared,
   // unless we are in debug mode or unless we are compiling a closure.
   if (num_copied_params == 0) {
-#ifdef DEBUG
-    ASSERT(!parsed_function().function().HasOptionalParameters());
-    const bool check_arguments = !flow_graph().IsCompiledForOsr();
-#else
     const bool check_arguments =
         function.IsClosureFunction() && !flow_graph().IsCompiledForOsr();
-#endif
     if (check_arguments) {
       __ Comment("Check argument count");
       // Check that exactly num_fixed arguments are passed in.
       Label correct_num_arguments, wrong_num_arguments;
       __ movq(RAX, FieldAddress(R10, ArgumentsDescriptor::count_offset()));
       __ CompareImmediate(RAX, Immediate(Smi::RawValue(num_fixed_params)));
       __ j(NOT_EQUAL, &wrong_num_arguments, Assembler::kNearJump);
       __ cmpq(RAX,
               FieldAddress(R10,
                            ArgumentsDescriptor::positional_count_offset()));
       __ j(EQUAL, &correct_num_arguments, Assembler::kNearJump);
 
       __ Bind(&wrong_num_arguments);
-      if (function.IsClosureFunction()) {
-        __ LeaveDartFrame(kKeepCalleePP);  // Leave arguments on the stack.
-        __ Jmp(*StubCode::CallClosureNoSuchMethod_entry());
-        // The noSuchMethod call may return to the caller, but not here.
-      } else {
-        __ Stop("Wrong number of arguments");
-      }
+      __ LeaveDartFrame(kKeepCalleePP);  // Leave arguments on the stack.
+      __ Jmp(*StubCode::CallClosureNoSuchMethod_entry());
+      // The noSuchMethod call may return to the caller, but not here.
       __ Bind(&correct_num_arguments);
     }
   } else if (!flow_graph().IsCompiledForOsr()) {
     CopyParameters();
   }
 
   if (function.IsClosureFunction() && !flow_graph().IsCompiledForOsr()) {
     // Load context from the closure object (first argument).
     LocalScope* scope = parsed_function().node_sequence()->scope();
     LocalVariable* closure_parameter = scope->VariableAt(0);
@@ skipping 311 matching lines @@
 }
 
 
 void FlowGraphCompiler::EmitOptimizedStaticCall(
     const Function& function,
     const Array& arguments_descriptor,
     intptr_t argument_count,
     intptr_t deopt_id,
     TokenPosition token_pos,
     LocationSummary* locs) {
-  __ LoadObject(R10, arguments_descriptor);
+  ASSERT(!function.IsClosureFunction());
+  if (function.HasOptionalParameters()) {
+    __ LoadObject(R10, arguments_descriptor);
+  } else {
+    __ xorq(R10, R10);  // GC safe smi zero because of stub.
+  }
   // Do not use the code from the function, but let the code be patched so that
   // we can record the outgoing edges to other code.
   GenerateStaticDartCall(deopt_id,
                          token_pos,
                          *StubCode::CallStaticFunction_entry(),
                          RawPcDescriptors::kOther,
                          locs,
                          function);
   __ Drop(argument_count, RCX);
 }
@@ skipping 434 matching lines @@
   __ movups(reg, Address(RSP, 0));
   __ AddImmediate(RSP, Immediate(kFpuRegisterSize));
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64