Attempt to reduce performance penalty for logging and profiling

src/log.cc

Index: src/log.cc
===================================================================
--- src/log.cc	(revision 2260)
+++ src/log.cc	(working copy)
@@ -31,9 +31,7 @@
 
 #include "bootstrapper.h"
 #include "log.h"
-#include "log-utils.h"
 #include "macro-assembler.h"
-#include "platform.h"
 #include "serialize.h"
 #include "string-stream.h"
 
@@ -304,6 +302,7 @@
 SlidingStateWindow* Logger::sliding_state_window_ = NULL;
 const char** Logger::log_events_ = NULL;
 CompressionHelper* Logger::compression_helper_ = NULL;
+bool Logger::is_logging_ = false;
 
 #define DECLARE_LONG_EVENT(ignore1, long_name, ignore2) long_name,
 const char* kLongLogEventsNames[Logger::NUMBER_OF_LOG_EVENTS] = {
@@ -318,11 +317,6 @@
 #undef DECLARE_SHORT_EVENT
 
 
-bool Logger::IsEnabled() {
-  return Log::IsEnabled();
-}
-
-
 void Logger::ProfilerBeginEvent() {
   if (!Log::IsEnabled()) return;
   LogMessageBuilder msg;
@@ -946,6 +940,7 @@
     // Must be the same message as Log::kDynamicBufferSeal.
     LOG(UncheckedStringEvent("profiler", "pause"));
   }
+  is_logging_ = false;
 }
 
 
@@ -953,6 +948,7 @@
   if (!profiler_->paused() || !Log::IsEnabled()) {
     return;
   }
+  is_logging_ = true;
   if (FLAG_prof_lazy) {
     LOG(UncheckedStringEvent("profiler", "resume"));
     FLAG_log_code = true;
@@ -1069,10 +1065,12 @@
     FLAG_prof_auto = false;
   }
 
-  bool open_log_file = FLAG_log || FLAG_log_runtime || FLAG_log_api
+  bool start_logging = FLAG_log || FLAG_log_runtime || FLAG_log_api
       || FLAG_log_code || FLAG_log_gc || FLAG_log_handles || FLAG_log_suspect
-      || FLAG_log_regexp || FLAG_log_state_changes || FLAG_prof_lazy;
+      || FLAG_log_regexp || FLAG_log_state_changes;
 
+  bool open_log_file = start_logging || FLAG_prof_lazy;
+
   // If we're logging anything, we need to open the log file.
   if (open_log_file) {
     if (strcmp(FLAG_logfile, "-") == 0) {
@@ -1134,10 +1132,15 @@
     compression_helper_ = new CompressionHelper(kCompressionWindowSize);
   }
 
+  is_logging_ = start_logging;
+
   if (FLAG_prof) {
     profiler_ = new Profiler();
-    if (!FLAG_prof_auto)
+    if (!FLAG_prof_auto) {
       profiler_->pause();
+    } else {
+      is_logging_ = true;
+    }
     profiler_->Engage();
   }
 
@@ -1195,85 +1198,4 @@
 }
 
 
-//
-// VMState class implementation.  A simple stack of VM states held by the
-// logger and partially threaded through the call stack.  States are pushed by
-// VMState construction and popped by destruction.
-//
-#ifdef ENABLE_LOGGING_AND_PROFILING
-static const char* StateToString(StateTag state) {
-  switch (state) {
-    case JS:
-      return "JS";
-    case GC:
-      return "GC";
-    case COMPILER:
-      return "COMPILER";
-    case OTHER:
-      return "OTHER";
-    default:
-      UNREACHABLE();
-      return NULL;
-  }
-}
-
-VMState::VMState(StateTag state) {
-#if !defined(ENABLE_HEAP_PROTECTION)
-  // When not protecting the heap, there is no difference between
-  // EXTERNAL and OTHER.  As an optimization in that case, we will not
-  // perform EXTERNAL->OTHER transitions through the API.  We thus
-  // compress the two states into one.
-  if (state == EXTERNAL) state = OTHER;
-#endif
-  state_ = state;
-  previous_ = Logger::current_state_;
-  Logger::current_state_ = this;
-
-  if (FLAG_log_state_changes) {
-    LOG(UncheckedStringEvent("Entering", StateToString(state_)));
-    if (previous_ != NULL) {
-      LOG(UncheckedStringEvent("From", StateToString(previous_->state_)));
-    }
-  }
-
-#ifdef ENABLE_HEAP_PROTECTION
-  if (FLAG_protect_heap && previous_ != NULL) {
-    if (state_ == EXTERNAL) {
-      // We are leaving V8.
-      ASSERT(previous_->state_ != EXTERNAL);
-      Heap::Protect();
-    } else if (previous_->state_ == EXTERNAL) {
-      // We are entering V8.
-      Heap::Unprotect();
-    }
-  }
-#endif
-}
-
-
-VMState::~VMState() {
-  Logger::current_state_ = previous_;
-
-  if (FLAG_log_state_changes) {
-    LOG(UncheckedStringEvent("Leaving", StateToString(state_)));
-    if (previous_ != NULL) {
-      LOG(UncheckedStringEvent("To", StateToString(previous_->state_)));
-    }
-  }
-
-#ifdef ENABLE_HEAP_PROTECTION
-  if (FLAG_protect_heap && previous_ != NULL) {
-    if (state_ == EXTERNAL) {
-      // We are reentering V8.
-      ASSERT(previous_->state_ != EXTERNAL);
-      Heap::Unprotect();
-    } else if (previous_->state_ == EXTERNAL) {
-      // We are leaving V8.
-      Heap::Protect();
-    }
-  }
-#endif
-}
-#endif
-
 } }  // namespace v8::internal