Move SimulatorHelper into V8 out of profiler clients.

src/profiler/tick-sample.cc

Index: src/profiler/tick-sample.cc
diff --git a/src/profiler/tick-sample.cc b/src/profiler/tick-sample.cc
index 8b7fe2c73ac6aceb20a324925a1331042a0f727b..fb5cdbff78eeaec5362b69f764db53380a87c49c 100644
--- a/src/profiler/tick-sample.cc
+++ b/src/profiler/tick-sample.cc
@@ -11,7 +11,6 @@
 #include "src/vm-state-inl.h"
 
 namespace v8 {
-
 namespace {
 
 bool IsSamePage(i::byte* ptr1, i::byte* ptr2) {
@@ -77,6 +76,73 @@ bool IsNoFrameRegion(i::Address address) {
 
 }  // namespace
 
+namespace internal {
+namespace {
+
+#if defined(USE_SIMULATOR)
+class SimulatorHelper {
+ public:
+  // Returns true if register values were successfully retrieved
+  // from the simulator, otherwise returns false.
+  static bool FillRegisters(Isolate* isolate, v8::RegisterState* state);
+};
+
+bool SimulatorHelper::FillRegisters(Isolate* isolate,
+                                    v8::RegisterState* state) {
+  Simulator* simulator = isolate->thread_local_top()->simulator_;
+  // Check if there is active simulator.
+  if (simulator == NULL) return false;
+#if V8_TARGET_ARCH_ARM
+  if (!simulator->has_bad_pc()) {
+    state->pc = reinterpret_cast<Address>(simulator->get_pc());
+  }
+  state->sp = reinterpret_cast<Address>(simulator->get_register(Simulator::sp));
+  state->fp =
+      reinterpret_cast<Address>(simulator->get_register(Simulator::r11));
+#elif V8_TARGET_ARCH_ARM64
+  state->pc = reinterpret_cast<Address>(simulator->pc());
+  state->sp = reinterpret_cast<Address>(simulator->sp());
+  state->fp = reinterpret_cast<Address>(simulator->fp());
+#elif V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
+  if (!simulator->has_bad_pc()) {
+    state->pc = reinterpret_cast<Address>(simulator->get_pc());
+  }
+  state->sp = reinterpret_cast<Address>(simulator->get_register(Simulator::sp));
+  state->fp = reinterpret_cast<Address>(simulator->get_register(Simulator::fp));
+#elif V8_TARGET_ARCH_PPC
+  if (!simulator->has_bad_pc()) {
+    state->pc = reinterpret_cast<Address>(simulator->get_pc());
+  }
+  state->sp = reinterpret_cast<Address>(simulator->get_register(Simulator::sp));
+  state->fp = reinterpret_cast<Address>(simulator->get_register(Simulator::fp));
+#elif V8_TARGET_ARCH_S390
+  if (!simulator->has_bad_pc()) {
+    state->pc = reinterpret_cast<Address>(simulator->get_pc());
+  }
+  state->sp = reinterpret_cast<Address>(simulator->get_register(Simulator::sp));
+  state->fp = reinterpret_cast<Address>(simulator->get_register(Simulator::fp));
+#endif
+  if (state->sp == 0 || state->fp == 0) {
+    // It possible that the simulator is interrupted while it is updating
+    // the sp or fp register. ARM64 simulator does this in two steps:
+    // first setting it to zero and then setting it to the new value.
+    // Bailout if sp/fp doesn't contain the new value.
+    //
+    // FIXME: The above doesn't really solve the issue.
+    // If a 64-bit target is executed on a 32-bit host even the final
+    // write is non-atomic, so it might obtain a half of the result.
+    // Moreover as long as the register set code uses memcpy (as of now),
+    // it is not guaranteed to be atomic even when both host and target
+    // are of same bitness.
+    return false;
+  }
+  return true;
+}
+#endif  // USE_SIMULATOR
+
+}  // namespace
+}  // namespace internal
+
 //
 // StackTracer implementation
 //
@@ -85,35 +151,33 @@ DISABLE_ASAN void TickSample::Init(Isolate* v8_isolate,
                                    RecordCEntryFrame record_c_entry_frame,
                                    bool update_stats) {
   this->update_stats = update_stats;
-
   SampleInfo info;
-  if (GetStackSample(v8_isolate, const_cast<RegisterState&>(regs),
-                     record_c_entry_frame, reinterpret_cast<void**>(&stack[0]),
-                     kMaxFramesCount, &info)) {
-    state = info.vm_state;
-    pc = regs.pc;
-    frames_count = static_cast<unsigned>(info.frames_count);
-    has_external_callback = info.external_callback_entry != nullptr;
-    if (has_external_callback) {
-      external_callback_entry = info.external_callback_entry;
-    } else if (frames_count) {
-      // sp register may point at an arbitrary place in memory, make
-      // sure MSAN doesn't complain about it.
-      MSAN_MEMORY_IS_INITIALIZED(regs.sp, sizeof(void*));
-      // Sample potential return address value for frameless invocation of
-      // stubs (we'll figure out later, if this value makes sense).
-      tos = i::Memory::Address_at(reinterpret_cast<i::Address>(regs.sp));
-    } else {
-      tos = nullptr;
-    }
-  } else {
+  if (!GetStackSample(v8_isolate, regs, record_c_entry_frame, stack,
+                      kMaxFramesCount, &info)) {
     // It is executing JS but failed to collect a stack trace.
     // Mark the sample as spoiled.
     pc = nullptr;
+    return;
+  }
+  state = info.vm_state;
+  pc = regs.pc;
+  frames_count = static_cast<unsigned>(info.frames_count);
+  has_external_callback = info.external_callback_entry != nullptr;
+  if (has_external_callback) {
+    external_callback_entry = info.external_callback_entry;
+  } else if (frames_count) {
+    // sp register may point at an arbitrary place in memory, make
+    // sure MSAN doesn't complain about it.
+    MSAN_MEMORY_IS_INITIALIZED(regs.sp, sizeof(void*));
+    // Sample potential return address value for frameless invocation of
+    // stubs (we'll figure out later, if this value makes sense).
+    tos = i::Memory::Address_at(reinterpret_cast<i::Address>(regs.sp));
+  } else {
+    tos = nullptr;
   }
 }
 
-bool TickSample::GetStackSample(Isolate* v8_isolate, const RegisterState& regs,
+bool TickSample::GetStackSample(Isolate* v8_isolate, const RegisterState& state,
                                 RecordCEntryFrame record_c_entry_frame,
                                 void** frames, size_t frames_limit,
                                 v8::SampleInfo* sample_info) {
@@ -125,10 +189,17 @@ bool TickSample::GetStackSample(Isolate* v8_isolate, const RegisterState& regs,
 
   i::Address js_entry_sp = isolate->js_entry_sp();
   if (js_entry_sp == nullptr) return true;  // Not executing JS now.
+
+#if defined(USE_SIMULATOR)
+  v8::RegisterState regs;
+  if (!i::SimulatorHelper::FillRegisters(isolate, &regs)) return false;
+#else
+  const v8::RegisterState& regs = state;
+#endif
   DCHECK(regs.sp);
 
   if (regs.pc && IsNoFrameRegion(static_cast<i::Address>(regs.pc))) {
-    // Can't collect stack.
+    // The frame is not setup, so it'd be hard to iterate the stack. Bailout.
     return false;
   }
 
@@ -183,59 +254,5 @@ void TickSample::Init(Isolate* isolate, const v8::RegisterState& state,
   timestamp = base::TimeTicks::HighResolutionNow();
 }
 
-#if defined(USE_SIMULATOR)
-bool SimulatorHelper::FillRegisters(Isolate* isolate,
-                                    v8::RegisterState* state) {
-  Simulator* simulator = isolate->thread_local_top()->simulator_;
-  // Check if there is active simulator.
-  if (simulator == NULL) return false;
-#if V8_TARGET_ARCH_ARM
-  if (!simulator->has_bad_pc()) {
-    state->pc = reinterpret_cast<Address>(simulator->get_pc());
-  }
-  state->sp = reinterpret_cast<Address>(simulator->get_register(Simulator::sp));
-  state->fp =
-      reinterpret_cast<Address>(simulator->get_register(Simulator::r11));
-#elif V8_TARGET_ARCH_ARM64
-  state->pc = reinterpret_cast<Address>(simulator->pc());
-  state->sp = reinterpret_cast<Address>(simulator->sp());
-  state->fp = reinterpret_cast<Address>(simulator->fp());
-#elif V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
-  if (!simulator->has_bad_pc()) {
-    state->pc = reinterpret_cast<Address>(simulator->get_pc());
-  }
-  state->sp = reinterpret_cast<Address>(simulator->get_register(Simulator::sp));
-  state->fp = reinterpret_cast<Address>(simulator->get_register(Simulator::fp));
-#elif V8_TARGET_ARCH_PPC
-  if (!simulator->has_bad_pc()) {
-    state->pc = reinterpret_cast<Address>(simulator->get_pc());
-  }
-  state->sp = reinterpret_cast<Address>(simulator->get_register(Simulator::sp));
-  state->fp = reinterpret_cast<Address>(simulator->get_register(Simulator::fp));
-#elif V8_TARGET_ARCH_S390
-  if (!simulator->has_bad_pc()) {
-    state->pc = reinterpret_cast<Address>(simulator->get_pc());
-  }
-  state->sp = reinterpret_cast<Address>(simulator->get_register(Simulator::sp));
-  state->fp = reinterpret_cast<Address>(simulator->get_register(Simulator::fp));
-#endif
-  if (state->sp == 0 || state->fp == 0) {
-    // It possible that the simulator is interrupted while it is updating
-    // the sp or fp register. ARM64 simulator does this in two steps:
-    // first setting it to zero and then setting it to the new value.
-    // Bailout if sp/fp doesn't contain the new value.
-    //
-    // FIXME: The above doesn't really solve the issue.
-    // If a 64-bit target is executed on a 32-bit host even the final
-    // write is non-atomic, so it might obtain a half of the result.
-    // Moreover as long as the register set code uses memcpy (as of now),
-    // it is not guaranteed to be atomic even when both host and target
-    // are of same bitness.
-    return false;
-  }
-  return true;
-}
-#endif  // USE_SIMULATOR
-
 }  // namespace internal
 }  // namespace v8