Implement optional parameter handling in ARM vm.

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 "lib/error.h"
@@ skipping 716 matching lines @@
         opt_param_position[i + 1] = opt_param_position[i];
       }
       opt_param[i + 1] = parameter;
       opt_param_position[i + 1] = pos;
     }
     // Generate code handling each optional parameter in alphabetical order.
     __ movq(RBX, FieldAddress(R10, ArgumentsDescriptor::count_offset()));
     __ movq(RCX,
             FieldAddress(R10, ArgumentsDescriptor::positional_count_offset()));
     __ SmiUntag(RCX);
-    // Let RBX point to the first passed argument, i.e. to fp[1 + argc - 0].
-    __ leaq(RBX, Address(RBP, RBX, TIMES_4, kWordSize));  // RBX is Smi.
+    // Let RBX point to the first passed argument, i.e. to
+    // fp[kLastParamSlotIndex + num_args - 1]; num_args (RBX) is Smi.
+    __ leaq(RBX,
+            Address(RBP, RBX, TIMES_4, (kLastParamSlotIndex - 1) * kWordSize));
     // Let RDI point to the entry of the first named argument.
     __ leaq(RDI,
             FieldAddress(R10, ArgumentsDescriptor::first_named_entry_offset()));
     for (int i = 0; i < num_opt_named_params; i++) {
-      Label load_default_value, assign_optional_parameter, next_parameter;
+      Label load_default_value, assign_optional_parameter;
       const int param_pos = opt_param_position[i];
       // Check if this named parameter was passed in.
       // Load RAX with the name of the argument.
       __ movq(RAX, Address(RDI, ArgumentsDescriptor::name_offset()));
       ASSERT(opt_param[i]->name().IsSymbol());
       __ CompareObject(RAX, opt_param[i]->name());
       __ j(NOT_EQUAL, &load_default_value, Assembler::kNearJump);
       // Load RAX with passed-in argument at provided arg_pos, i.e. at
-      // fp[1 + argc - arg_pos].
+      // fp[kLastParamSlotIndex + num_args - 1 - arg_pos].
       __ movq(RAX, Address(RDI, ArgumentsDescriptor::position_offset()));
       // RAX is arg_pos as Smi.
       // Point to next named entry.
       __ addq(RDI, Immediate(ArgumentsDescriptor::named_entry_size()));
       __ negq(RAX);
       Address argument_addr(RBX, RAX, TIMES_4, 0);  // RAX is a negative Smi.
       __ movq(RAX, argument_addr);
       __ jmp(&assign_optional_parameter, Assembler::kNearJump);
       __ Bind(&load_default_value);
       // Load RAX with default argument.
       const Object& value = Object::ZoneHandle(
           parsed_function().default_parameter_values().At(
               param_pos - num_fixed_params));
       __ LoadObject(RAX, value);
       __ Bind(&assign_optional_parameter);
       // Assign RAX to fp[kFirstLocalSlotIndex - param_pos].
       // We do not use the final allocation index of the variable here, i.e.
       // scope->VariableAt(i)->index(), because captured variables still need
       // to be copied to the context that is not yet allocated.
       const intptr_t computed_param_pos = kFirstLocalSlotIndex - param_pos;
-      const Address param_addr(RBP, (computed_param_pos * kWordSize));
+      const Address param_addr(RBP, computed_param_pos * kWordSize);
       __ movq(param_addr, RAX);
-      __ Bind(&next_parameter);
     }
     delete[] opt_param;
     delete[] opt_param_position;
     // Check that RDI now points to the null terminator in the array descriptor.
     __ cmpq(Address(RDI, 0), raw_null);
     __ j(EQUAL, &all_arguments_processed, Assembler::kNearJump);
   } else {
     ASSERT(num_opt_pos_params > 0);
     __ movq(RCX,
             FieldAddress(R10, ArgumentsDescriptor::positional_count_offset()));
     __ SmiUntag(RCX);
     for (int i = 0; i < num_opt_pos_params; i++) {
       Label next_parameter;
-      // Handle this optional positonal parameter only if k or fewer positional
+      // Handle this optional positional parameter only if k or fewer positional
       // arguments have been passed, where k is param_pos, the position of this
       // optional parameter in the formal parameter list.
       const int param_pos = num_fixed_params + i;
       __ cmpq(RCX, Immediate(param_pos));
       __ j(GREATER, &next_parameter, Assembler::kNearJump);
       // Load RAX with default argument.
       const Object& value = Object::ZoneHandle(
           parsed_function().default_parameter_values().At(i));
       __ LoadObject(RAX, value);
       // Assign RAX to fp[kFirstLocalSlotIndex - param_pos].
       // We do not use the final allocation index of the variable here, i.e.
       // scope->VariableAt(i)->index(), because captured variables still need
       // to be copied to the context that is not yet allocated.
       const intptr_t computed_param_pos = kFirstLocalSlotIndex - param_pos;
-      const Address param_addr(RBP, (computed_param_pos * kWordSize));
+      const Address param_addr(RBP, computed_param_pos * kWordSize);
       __ movq(param_addr, RAX);
       __ Bind(&next_parameter);
     }
     __ movq(RBX, FieldAddress(R10, ArgumentsDescriptor::count_offset()));
     __ SmiUntag(RBX);
     // Check that RCX equals RBX, i.e. no named arguments passed.
     __ cmpq(RCX, RBX);
     __ j(EQUAL, &all_arguments_processed, Assembler::kNearJump);
   }
 
@@ skipping 38 matching lines @@
   // checked, otherwise noSuchMethod would not see their original values.
   // This step can be skipped in case we decide that formal parameters are
   // implicitly final, since garbage collecting the unmodified value is not
   // an issue anymore.
 
   // R10 : arguments descriptor array.
   __ movq(RCX, FieldAddress(R10, ArgumentsDescriptor::count_offset()));
   __ SmiUntag(RCX);
   Label null_args_loop, null_args_loop_condition;
   __ jmp(&null_args_loop_condition, Assembler::kNearJump);
-  const Address original_argument_addr(RBP, RCX, TIMES_8, 2 * kWordSize);
+  const Address original_argument_addr(
+      RBP, RCX, TIMES_8, kLastParamSlotIndex * kWordSize);
   __ Bind(&null_args_loop);
   __ movq(original_argument_addr, raw_null);
   __ Bind(&null_args_loop_condition);
   __ decq(RCX);
   __ j(POSITIVE, &null_args_loop, Assembler::kNearJump);
 }
 
 
 void FlowGraphCompiler::GenerateInlinedGetter(intptr_t offset) {
   // TOS: return address.
@@ skipping 815 matching lines @@
 void ParallelMoveResolver::Exchange(const Address& mem1, const Address& mem2) {
   __ Exchange(mem1, mem2);
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64