Implement rewind: drop one or more frames from the debugger.

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 519 matching lines @@
   __ 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(R2, ASR, kSmiTagSize));
-  __ Ret();
+  // The caller is responsible for emitting the return instruction.
 }
 
 
 // R0: result, must be preserved
 void StubCode::GenerateDeoptimizeLazyFromReturnStub(Assembler* assembler) {
   // Push zap value instead of CODE_REG for lazy deopt.
-  __ LoadImmediate(IP, 0xf1f1f1f1);
+  __ LoadImmediate(IP, kZapCodeReg);
   __ Push(IP);
   // Return address for "call" to deopt stub.
-  __ LoadImmediate(LR, 0xe1e1e1e1);
+  __ LoadImmediate(LR, kZapReturnAddress);
   __ ldr(CODE_REG, Address(THR, Thread::lazy_deopt_from_return_stub_offset()));
   GenerateDeoptimizationSequence(assembler, kLazyDeoptFromReturn);
+  __ Ret();
 }
 
 
 // R0: exception, must be preserved
 // R1: stacktrace, must be preserved
 void StubCode::GenerateDeoptimizeLazyFromThrowStub(Assembler* assembler) {
   // Push zap value instead of CODE_REG for lazy deopt.
-  __ LoadImmediate(IP, 0xf1f1f1f1);
+  __ LoadImmediate(IP, kZapCodeReg);
   __ Push(IP);
   // Return address for "call" to deopt stub.
-  __ LoadImmediate(LR, 0xe1e1e1e1);
+  __ LoadImmediate(LR, kZapReturnAddress);
   __ ldr(CODE_REG, Address(THR, Thread::lazy_deopt_from_throw_stub_offset()));
   GenerateDeoptimizationSequence(assembler, kLazyDeoptFromThrow);
+  __ Ret();
 }
 
 
 void StubCode::GenerateDeoptimizeStub(Assembler* assembler) {
   GenerateDeoptimizationSequence(assembler, kEagerDeopt);
+  __ Ret();
 }
 
 
 static void GenerateDispatcherCode(Assembler* assembler,
                                    Label* call_target_function) {
   __ Comment("NoSuchMethodDispatch");
   // When lazily generated invocation dispatchers are disabled, the
   // miss-handler may return null.
   __ CompareObject(R0, Object::null_object());
   __ b(call_target_function, NE);
@@ skipping 1311 matching lines @@
   __ StoreToOffset(kWord, R2, THR, Thread::active_exception_offset());
 
   // Stacktrace object.
   __ LoadFromOffset(kWord, R1, THR, Thread::active_stacktrace_offset());
   __ StoreToOffset(kWord, R2, THR, Thread::active_stacktrace_offset());
 
   __ bx(LR);  // Jump to the exception handler code.
 }
 
 
+// Deoptimize a frame on the call stack before rewinding.
+// The arguments are stored in the Thread object.
+// No result.
+void StubCode::GenerateDeoptForRewindStub(Assembler* assembler) {
+  // Push zap value instead of CODE_REG.
+  __ LoadImmediate(IP, kZapCodeReg);
+  __ Push(IP);
+
+  // Load the deopt pc into LR.
+  __ LoadFromOffset(kWord, LR, THR, Thread::resume_pc_offset());
+  GenerateDeoptimizationSequence(assembler, kEagerDeopt);
+
+  // After we have deoptimized, jump to the correct frame.
+  __ EnterStubFrame();
+  __ CallRuntime(kRewindPostDeoptRuntimeEntry, 0);
+  __ LeaveStubFrame();
+  __ bkpt(0);
+}
+
+
 // Calls to the runtime to optimize the given function.
 // R8: function to be reoptimized.
 // R4: argument descriptor (preserved).
 void StubCode::GenerateOptimizeFunctionStub(Assembler* assembler) {
   __ EnterStubFrame();
   __ Push(R4);
   __ LoadImmediate(IP, 0);
   __ Push(IP);  // Setup space on stack for return value.
   __ Push(R8);
   __ CallRuntime(kOptimizeInvokedFunctionRuntimeEntry, 1);
@@ skipping 346 matching lines @@
 }
 
 
 void StubCode::GenerateFrameAwaitingMaterializationStub(Assembler* assembler) {
   __ bkpt(0);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM