Adding 'isolates' argument to LOG to get rid of multiple TLS fetches in profiling.

src/platform-linux.cc

Index: src/platform-linux.cc
diff --git a/src/platform-linux.cc b/src/platform-linux.cc
index 1de74164479f4a20230a52194b0f9f65cf5fe41a..c5bd89eac0775a9360f88311a783cf4ff12780a2 100644
--- a/src/platform-linux.cc
+++ b/src/platform-linux.cc
@@ -257,7 +257,7 @@ void* OS::Allocate(const size_t requested,
   int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
   void* mbase = mmap(NULL, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
   if (mbase == MAP_FAILED) {
-    LOG(StringEvent("OS::Allocate", "mmap failed"));
+    LOG(ISOLATE,StringEvent("OS::Allocate", "mmap failed"));
     return NULL;
   }
   *allocated = msize;
@@ -378,6 +378,7 @@ void OS::LogSharedLibraryAddresses() {
   const int kLibNameLen = FILENAME_MAX + 1;
   char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen));
 
+  i::Isolate* isolate = ISOLATE;
   // This loop will terminate once the scanning hits an EOF.
   while (true) {
     uintptr_t start, end;
@@ -411,7 +412,7 @@ void OS::LogSharedLibraryAddresses() {
         snprintf(lib_name, kLibNameLen,
                  "%08" V8PRIxPTR "-%08" V8PRIxPTR, start, end);
       }
-      LOG(SharedLibraryEvent(lib_name, start, end));
+      LOG(isolate, SharedLibraryEvent(lib_name, start, end));
     } else {
       // Entry not describing executable data. Skip to end of line to setup
       // reading the next entry.