Lazy deopt without code patching.

runtime/vm/stub_code_arm.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_ARM)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/cpu.h"
@@ skipping 504 matching lines @@
   if (kind == kLazyDeoptFromReturn) {
     __ Push(R1);  // Preserve result, it will be GC-d here.
   } else if (kind == kLazyDeoptFromThrow) {
     __ Push(R1);  // Preserve exception, it will be GC-d here.
     __ Push(R2);  // Preserve stacktrace, it will be GC-d here.
   }
   __ PushObject(Smi::ZoneHandle());  // Space for the result.
   __ CallRuntime(kDeoptimizeMaterializeRuntimeEntry, 0);
   // Result tells stub how many bytes to remove from the expression stack
   // of the bottom-most frame. They were used as materialization arguments.
-  __ Pop(R1);
+  __ Pop(R2);
   if (kind == kLazyDeoptFromReturn) {
     __ Pop(R0);  // Restore result.
   } else if (kind == kLazyDeoptFromThrow) {
     __ Pop(R1);  // Restore stacktrace.
     __ Pop(R0);  // Restore exception.
   }
   __ LeaveStubFrame();
   // Remove materialization arguments.
-  __ add(SP, SP, Operand(R1, ASR, kSmiTagSize));
+  __ add(SP, SP, Operand(R2, ASR, kSmiTagSize));
   __ Ret();
 }
 
 
-// LR: return address + call-instruction-size
 // R0: result, must be preserved
 void StubCode::GenerateDeoptimizeLazyFromReturnStub(Assembler* assembler) {
-  // Correct return address to point just after the call that is being
-  // deoptimized.
-  __ AddImmediate(LR, -CallPattern::DeoptCallPatternLengthInBytes());
   // Push zap value instead of CODE_REG for lazy deopt.
   __ LoadImmediate(IP, 0xf1f1f1f1);
   __ Push(IP);
+  // Return address for "call" to deopt stub.
+  __ LoadImmediate(LR, 0xe1e1e1e1);
+  __ ldr(CODE_REG, Address(THR, Thread::lazy_deopt_from_return_stub_offset()));
   GenerateDeoptimizationSequence(assembler, kLazyDeoptFromReturn);
 }
 
 
-// LR: return address + call-instruction-size
 // R0: exception, must be preserved
 // R1: stacktrace, must be preserved
 void StubCode::GenerateDeoptimizeLazyFromThrowStub(Assembler* assembler) {
-  // Correct return address to point just after the call that is being
-  // deoptimized.
-  __ AddImmediate(LR, -CallPattern::DeoptCallPatternLengthInBytes());
   // Push zap value instead of CODE_REG for lazy deopt.
   __ LoadImmediate(IP, 0xf1f1f1f1);
   __ Push(IP);
+  // Return address for "call" to deopt stub.
+  __ LoadImmediate(LR, 0xe1e1e1e1);
+  __ ldr(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 1684 matching lines @@
 }
 
 
 void StubCode::GenerateFrameAwaitingMaterializationStub(Assembler* assembler) {
   __ bkpt(0);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM