Reapply "Lazy deopt without code patching."

runtime/vm/stub_code_x64.cc

 // Copyright (c) 2013, 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"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 479 matching lines @@
   }
   __ LeaveStubFrame();
 
   __ popq(RCX);  // Pop return address.
   __ addq(RSP, RBX);  // Remove materialization arguments.
   __ pushq(RCX);  // Push return address.
   __ ret();
 }
 
 
-// TOS: return address + call-instruction-size (5 bytes).
 // RAX: result, must be preserved
 void StubCode::GenerateDeoptimizeLazyFromReturnStub(Assembler* assembler) {
-  // Correct return address to point just after the call that is being
-  // deoptimized.
-  __ popq(RBX);
-  __ subq(RBX, Immediate(ShortCallPattern::pattern_length_in_bytes()));
   // Push zap value instead of CODE_REG for lazy deopt.
   __ pushq(Immediate(0xf1f1f1f1));
-  __ pushq(RBX);
+  // Return address for "call" to deopt stub.
+  __ pushq(Immediate(0xe1e1e1e1));
+  __ movq(CODE_REG, Address(THR, Thread::lazy_deopt_from_return_stub_offset()));
   GenerateDeoptimizationSequence(assembler, kLazyDeoptFromReturn);
 }
 
 
-// TOS: return address + call-instruction-size (5 bytes).
 // RAX: exception, must be preserved
 // RDX: stacktrace, must be preserved
 void StubCode::GenerateDeoptimizeLazyFromThrowStub(Assembler* assembler) {
-  // Correct return address to point just after the call that is being
-  // deoptimized.
-  __ popq(RBX);
-  __ subq(RBX, Immediate(ShortCallPattern::pattern_length_in_bytes()));
   // Push zap value instead of CODE_REG for lazy deopt.
   __ pushq(Immediate(0xf1f1f1f1));
-  __ pushq(RBX);
+  // Return address for "call" to deopt stub.
+  __ pushq(Immediate(0xe1e1e1e1));
+  __ movq(CODE_REG, Address(THR, Thread::lazy_deopt_from_throw_stub_offset()));
   GenerateDeoptimizationSequence(assembler, kLazyDeoptFromThrow);
 }
 
 
 void StubCode::GenerateDeoptimizeStub(Assembler* assembler) {
   GenerateDeoptimizationSequence(assembler, kEagerDeopt);
 }
 
 
 static void GenerateDispatcherCode(Assembler* assembler,
@@ skipping 1748 matching lines @@
 }
 
 
 void StubCode::GenerateFrameAwaitingMaterializationStub(Assembler* assembler) {
   __ int3();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64