Initial SIMDBC interpreter.

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 4b1124785de7ad9019f6e452420de901fca1c876..0de6fd68299469cef0baf4498c70e6f3a6887a2b 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -982,8 +982,13 @@ Isolate* Isolate::Init(const char* name_prefix,
 uword Isolate::GetCurrentStackPointer() {
   // Since AddressSanitizer's detect_stack_use_after_return instruments the
   // C++ code to give out fake stack addresses, we call a stub in that case.
-  uword (*func)() = reinterpret_cast<uword (*)()>(
-      StubCode::GetStackPointer_entry()->EntryPoint());
+  uword (*func)() =
+#if !defined(TARGET_ARCH_DBC)
+      reinterpret_cast<uword (*)()>(
+          StubCode::GetStackPointer_entry()->EntryPoint());
+#else
+      NULL;
+#endif
   // But for performance (and to support simulators), we normally use a local.
 #if defined(__has_feature)
 #if __has_feature(address_sanitizer)
@@ -1056,14 +1061,18 @@ void Isolate::BuildName(const char* name_prefix) {
 
 void Isolate::SetStackLimitFromStackBase(uword stack_base) {
   // Set stack limit.
+#if !defined(TARGET_ARCH_DBC)
 #if defined(USING_SIMULATOR)
   // Ignore passed-in native stack top and use Simulator stack top.
   Simulator* sim = Simulator::Current();  // May allocate a simulator.
   ASSERT(simulator() == sim);  // This isolate's simulator is the current one.
   stack_base = sim->StackTop();
   // The overflow area is accounted for by the simulator.
-#endif
+#endif  // defined(USING_SIMULATOR)
   SetStackLimit(stack_base - OSThread::GetSpecifiedStackSize());
+#else
+  SetStackLimit(Simulator::Current()->StackTop());
+#endif  // !defined(TARGET_ARCH_DBC)
 }
 
 
@@ -1502,7 +1511,11 @@ void Isolate::ScheduleInterrupts(uword interrupt_bits) {
   }
 
   if (stack_limit_ == saved_stack_limit_) {
+#if !defined(TARGET_ARCH_DBC)
     stack_limit_ = (~static_cast<uword>(0)) & ~kInterruptsMask;
+#else
+    stack_limit_ = 0;
+#endif
   }
   stack_limit_ |= interrupt_bits;
 }
@@ -1549,7 +1562,11 @@ void Isolate::RestoreOOBMessageInterrupts() {
   deferred_interrupts_mask_ = 0;
   if (deferred_interrupts_ != 0) {
     if (stack_limit_ == saved_stack_limit_) {
+#if !defined(TARGET_ARCH_DBC)
       stack_limit_ = (~static_cast<uword>(0)) & ~kInterruptsMask;
+#else
+      stack_limit_ = 0;
+#endif
     }
     stack_limit_ |= deferred_interrupts_;
     deferred_interrupts_ = 0;