Make allocation of Dart parameters and local variables architecture independent.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 20045)
+++ runtime/vm/parser.cc	(working copy)
@@ -158,10 +158,10 @@
   // Compute start indices to parameters and locals, and the number of
   // parameters to copy.
   if (num_opt_params == 0) {
-    // Parameter i will be at fp[1 + num_params - i] and local variable
-    // j will be at fp[kFirstLocalSlotIndex - j].
+    // Parameter i will be at fp[kLastParamSlotIndex + num_params - 1 - i] and
+    // local variable j will be at fp[kFirstLocalSlotIndex - j].
     ASSERT(GetSavedArgumentsDescriptorVar() == NULL);
-    first_parameter_index_ = 1 + num_params;
+    first_parameter_index_ = kLastParamSlotIndex + num_params - 1;

[zra, 2013/03/14 21:14:20]

It's a little surprising that the parser has to know something about the stack
layout.

[regis, 2013/03/14 21:32:22]

Yes, indeed. Allocating variables was moved out of the old code generator when
the new optimizing code generator was written. This allocation is actually
fairly high level. We just assign a slot index to parameters and locals. It does
not prevent locals to be ultimately allocated in registers, for example. The
index reflects more the position of parameters and position of local variables
in their respective scopes (or contexts, if captured) than their actual memory
address or register.  

     first_stack_local_index_ = kFirstLocalSlotIndex;
     num_copied_params_ = 0;
   } else {