Add support for fixed parameters in the register allocator.

runtime/vm/flow_graph_compiler.cc

Index: runtime/vm/flow_graph_compiler.cc
diff --git a/runtime/vm/flow_graph_compiler.cc b/runtime/vm/flow_graph_compiler.cc
index 29c2fe05e5adcc1c4c609fdbe4617d13b65bffb0..4509ea81b026d1deaa40d7f2b60b1f41d39bf4b9 100644
--- a/runtime/vm/flow_graph_compiler.cc
+++ b/runtime/vm/flow_graph_compiler.cc
@@ -141,8 +141,12 @@ void FlowGraphCompiler::Bailout(const char* reason) {
 
 
 intptr_t FlowGraphCompiler::StackSize() const {
-  return parsed_function_.stack_local_count() +
-      parsed_function_.copied_parameter_count();
+  if (is_ssa_) {
+    return block_order_[0]->AsGraphEntry()->spill_slot_count();

[Kevin Millikin (Google), 2012/07/26 09:29:08]

I think it's a little weird that the spill slot count is in the graph entry. 
It's not really a property of the graph, but of a certain register allocation. 
It seems like it belongs in the compiler, or the register allocator.

[Vyacheslav Egorov (Google), 2012/07/26 11:33:53]

Discussed offline. My reasoning is that each instruction in the graph already
owns locations (register and spill slots) at this point so attaching spill slot
count to the graph itself seems logical. 

+  } else {
+    return parsed_function_.stack_local_count() +
+        parsed_function_.copied_parameter_count();
+  }
 }