Use the inner deoptimization frame when setting incoming arguments.

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 543db79fad6bbfe0b1b48e47c90b039ca767c9d1..40b7259b8a8bef75543fbbb5d0c5f49f38da4db1 100644
--- a/runtime/vm/flow_graph_compiler.cc
+++ b/runtime/vm/flow_graph_compiler.cc
@@ -77,39 +77,56 @@ RawDeoptInfo* CompilerDeoptInfo::CreateDeoptInfo(FlowGraphCompiler* compiler) {
 
   intptr_t slot_ix = 0;
   Environment* env = deoptimization_env_;
-  while (env != NULL) {
-    const Function& function = env->function();
-    const intptr_t fixed_parameter_count = env->fixed_parameter_count();
 
-    if (slot_ix == 0) {
-      // For the innermost environment call the virtual return builder.
-      BuildReturnAddress(&builder, function, slot_ix++);
-    } else {
-      // For any outer environment the deopt id is that of the call instruction
-      // which is recorded in the outer environment.
-      builder.AddReturnAddressAfter(function, env->deopt_id(), slot_ix++);
-    }
+  // For the innermost environment, call the virtual return builder.
+  BuildReturnAddress(&builder, env->function(), slot_ix++);
+
+  // For the innermost environment, set outgoing arguments and the locals.
+  for (intptr_t i = env->Length() - 1; i >= env->fixed_parameter_count(); i--) {
+    builder.AddCopy(env->LocationAt(i), *env->ValueAt(i), slot_ix++);
+  }
 
-    for (intptr_t i = env->Length() - 1; i >= fixed_parameter_count; i--) {
+  // PC marker and caller FP.
+  builder.AddPcMarker(env->function(), slot_ix++);
+  builder.AddCallerFp(slot_ix++);
+
+  while (env->outer() != NULL) {
+    const Environment* outer = env->outer();
+
+    // For any outer environment the deopt id is that of the call instruction
+    // which is recorded in the outer environment.
+    builder.AddReturnAddressAfter(outer->function(),
+                                  outer->deopt_id(),
+                                  slot_ix++);
+
+    // Set incoming arguments from the inner frame.

[Vyacheslav Egorov (Google), 2012/09/21 14:38:30]

Please add a comment that clarifies that values of incoming arguments can be
changed by the inner function and thus they have to be taken from the inner
frame.

[zerny-google, 2012/09/21 14:55:47]

Done.

+    for (intptr_t i = env->fixed_parameter_count() - 1; i >= 0; i--) {
       builder.AddCopy(env->LocationAt(i), *env->ValueAt(i), slot_ix++);
     }
 
+    // Set the locals, not including the outgoing arguments.

[Vyacheslav Egorov (Google), 2012/09/21 14:38:30]

I would add an assertion here that outer->Length() is bigger than
inner->fixed_parameter_count().

[zerny-google, 2012/09/21 14:55:47]

Done.

+    for (intptr_t i = outer->Length() - env->fixed_parameter_count() - 1;
+         i >= outer->fixed_parameter_count();
+         i--) {
+      builder.AddCopy(outer->LocationAt(i), *outer->ValueAt(i), slot_ix++);
+    }
+
     // PC marker and caller FP.
-    builder.AddPcMarker(function, slot_ix++);
+    builder.AddPcMarker(outer->function(), slot_ix++);
     builder.AddCallerFp(slot_ix++);
 
-    // On the outermost environment set caller PC and incoming arguments.
-    if (env->outer() == NULL) {
-      builder.AddCallerPc(slot_ix++);
-      for (intptr_t i = fixed_parameter_count - 1; i >= 0; i--) {
-        builder.AddCopy(env->LocationAt(i), *env->ValueAt(i), slot_ix++);
-      }
-    }
-
     // Iterate on the outer environment.
     env = env->outer();
   }
 
+  // For the outermost environment, set caller PC.
+  builder.AddCallerPc(slot_ix++);
+
+  // For the outermost environment, set the incoming arguments.
+  for (intptr_t i = env->fixed_parameter_count() - 1; i >= 0; i--) {
+    builder.AddCopy(env->LocationAt(i), *env->ValueAt(i), slot_ix++);
+  }
+
   const DeoptInfo& deopt_info = DeoptInfo::Handle(builder.CreateDeoptInfo());
   return deopt_info.raw();
 }