Make allocation of Dart parameters and local variables architecture independent.

runtime/vm/flow_graph_compiler_x64.cc

Index: runtime/vm/flow_graph_compiler_x64.cc
===================================================================
--- runtime/vm/flow_graph_compiler_x64.cc	(revision 20045)
+++ runtime/vm/flow_graph_compiler_x64.cc	(working copy)
@@ -651,8 +651,7 @@
   const int num_params =
       num_fixed_params + num_opt_pos_params + num_opt_named_params;
   ASSERT(function.NumParameters() == num_params);
-  ASSERT(parsed_function().first_parameter_index() ==
-         ParsedFunction::kFirstLocalSlotIndex);
+  ASSERT(parsed_function().first_parameter_index() == kFirstLocalSlotIndex);
 
   // Check that min_num_pos_args <= num_pos_args <= max_num_pos_args,
   // where num_pos_args is the number of positional arguments passed in.
@@ -670,25 +669,24 @@
   __ j(GREATER, &wrong_num_arguments);
 
   // Copy positional arguments.
-  // Argument i passed at fp[1 + num_args - i] is copied
-  // to fp[ParsedFunction::kFirstLocalSlotIndex - i].
+  // Argument i passed at fp[kLastParamSlotIndex + num_args - 1 - i] is copied
+  // to fp[kFirstLocalSlotIndex - i].
 
   __ movq(RBX, FieldAddress(R10, ArgumentsDescriptor::count_offset()));
   // Since RBX and RCX are Smi, use TIMES_4 instead of TIMES_8.
   // Let RBX point to the last passed positional argument, i.e. to
-  // fp[1 + num_args - (num_pos_args - 1)].
+  // fp[kLastParamSlotIndex + num_args - 1 - (num_pos_args - 1)].
   __ subq(RBX, RCX);
-  __ leaq(RBX, Address(RBP, RBX, TIMES_4, 2 * kWordSize));
+  __ leaq(RBX, Address(RBP, RBX, TIMES_4, kLastParamSlotIndex * kWordSize));
 
   // Let RDI point to the last copied positional argument, i.e. to
-  // fp[ParsedFunction::kFirstLocalSlotIndex - (num_pos_args - 1)].
-  const int index = ParsedFunction::kFirstLocalSlotIndex + 1;
+  // fp[kFirstLocalSlotIndex - (num_pos_args - 1)].
   __ SmiUntag(RCX);
   __ movq(RAX, RCX);
   __ negq(RAX);
   // -num_pos_args is in RAX.
-  // (ParsedFunction::kFirstLocalSlotIndex + 1) is in index.
-  __ leaq(RDI, Address(RBP, RAX, TIMES_8, (index * kWordSize)));
+  __ leaq(RDI,
+          Address(RBP, RAX, TIMES_8, (kFirstLocalSlotIndex + 1) * kWordSize));
   Label loop, loop_condition;
   __ jmp(&loop_condition, Assembler::kNearJump);
   // We do not use the final allocation index of the variable here, i.e.
@@ -762,12 +760,11 @@
               param_pos - num_fixed_params));
       __ LoadObject(RAX, value);
       __ Bind(&assign_optional_parameter);
-      // Assign RAX to fp[ParsedFunction::kFirstLocalSlotIndex - param_pos].
+      // 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 =
-          ParsedFunction::kFirstLocalSlotIndex - param_pos;
+      const intptr_t computed_param_pos = kFirstLocalSlotIndex - param_pos;
       const Address param_addr(RBP, (computed_param_pos * kWordSize));
       __ movq(param_addr, RAX);
       __ Bind(&next_parameter);
@@ -794,12 +791,11 @@
       const Object& value = Object::ZoneHandle(
           parsed_function().default_parameter_values().At(i));
       __ LoadObject(RAX, value);
-      // Assign RAX to fp[ParsedFunction::kFirstLocalSlotIndex - param_pos].
+      // 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 =
-          ParsedFunction::kFirstLocalSlotIndex - param_pos;
+      const intptr_t computed_param_pos = kFirstLocalSlotIndex - param_pos;
       const Address param_addr(RBP, (computed_param_pos * kWordSize));
       __ movq(param_addr, RAX);
       __ Bind(&next_parameter);