[liveedit] reimplement frame restarting.

src/arm64/macro-assembler-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 2880 matching lines @@
 
 
 void MacroAssembler::DebugBreak() {
   Mov(x0, 0);
   Mov(x1, ExternalReference(Runtime::kHandleDebuggerStatement, isolate()));
   CEntryStub ces(isolate(), 1);
   DCHECK(AllowThisStubCall(&ces));
   Call(ces.GetCode(), RelocInfo::DEBUGGER_STATEMENT);
 }
 
+void MacroAssembler::MaybeDropFrames() {
+  // Check whether we need to drop frames to restart a function on the stack.
+  ExternalReference restart_fp =
+      ExternalReference::debug_restart_fp_address(isolate());
+  Mov(x1, Operand(restart_fp));
+  Ldr(x1, MemOperand(x1));
+  Tst(x1, x1);
+  Jump(isolate()->builtins()->FrameDropperTrampoline(), RelocInfo::CODE_TARGET,
+       ne);
+}
 
 void MacroAssembler::PushStackHandler() {
   DCHECK(jssp.Is(StackPointer()));
   // Adjust this code if the asserts don't hold.
   STATIC_ASSERT(StackHandlerConstants::kSize == 1 * kPointerSize);
   STATIC_ASSERT(StackHandlerConstants::kNextOffset == 0 * kPointerSize);
 
   // For the JSEntry handler, we must preserve the live registers x0-x4.
   // (See JSEntryStub::GenerateBody().)
 
@@ skipping 1757 matching lines @@
 }
 
 
 #undef __
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM64