Deoptimization can occur at Dart calls (includes native calls to C) but not at runtime calls. This …

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2012, 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/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 268 matching lines @@
   locs->set_out(Location::RegisterLocation(RAX));
   return locs;
 }
 
 
 static void EmitEqualityAsInstanceCall(FlowGraphCompiler* compiler,
                                        intptr_t deopt_id,
                                        intptr_t token_pos,
                                        Token::Kind kind,
                                        LocationSummary* locs) {
-  compiler->AddCurrentDescriptor(PcDescriptors::kDeopt,
+  compiler->AddCurrentDescriptor(PcDescriptors::kDeoptBefore,
                                  deopt_id,
                                  token_pos);
   const String& operator_name = String::ZoneHandle(Symbols::New("=="));
   const int kNumberOfArguments = 2;
   const Array& kNoArgumentNames = Array::Handle();
   const int kNumArgumentsChecked = 2;
 
   Label done, false_label, true_label;
   Register left = locs->in(0).reg();
   Register right = locs->in(1).reg();
@@ skipping 447 matching lines @@
                               kNumArguments,
                               Array::Handle(),  // No named arguments.
                               deopt,  // Deoptimize target.
                               deopt_id(),
                               token_pos(),
                               locs());
     return;
   }
   const String& function_name =
       String::ZoneHandle(Symbols::New(Token::Str(kind())));
-  compiler->AddCurrentDescriptor(PcDescriptors::kDeopt,
+  compiler->AddCurrentDescriptor(PcDescriptors::kDeoptBefore,
                                  deopt_id(),
                                  token_pos());
   const intptr_t kNumArguments = 2;
   const intptr_t kNumArgsChecked = 2;  // Type-feedback.
   compiler->GenerateInstanceCall(deopt_id(),
                                  token_pos(),
                                  function_name,
                                  kNumArguments,
                                  Array::ZoneHandle(),  // No optional arguments.
                                  kNumArgsChecked,
@@ skipping 1465 matching lines @@
   }
   __ j(ABOVE_EQUAL, deopt);
 }
 
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64