Revert "Disable optimization of Atomic::LoadJavaData for x86 targets."

This reverts commit fbd5118c1c36900910cabe89e3a73d598160e629.

Reason for revert: <INSERT REASONING HERE>

Change-Id: If7aac5e7f4e5376167e896c40f8bf30287f81dd1
diff --git a/runtime/atomic.h b/runtime/atomic.h
index 090e56a..e2a7259 100644
--- a/runtime/atomic.h
+++ b/runtime/atomic.h
@@ -201,11 +201,6 @@
     return this->load(std::memory_order_acquire);
   }
 
-  // Disable optimizations for Atomic::LoadJavaData on x86 devices.
-  // Bug: http://b/34287931
-#if defined(DISABLE_LOAD_JAVA_DATA_OPTIMIZATIONS)
-  #pragma clang optimize off
-#endif
   // Word tearing allowed, but may race.
   // TODO: Optimize?
   // There has been some discussion of eventually disallowing word
@@ -213,9 +208,6 @@
   T LoadJavaData() const {
     return this->load(std::memory_order_relaxed);
   }
-#if defined(DISABLE_LOAD_JAVA_DATA_OPTIMIZATIONS)
-  #pragma clang optimize on
-#endif
 
   // Load from memory with a total ordering.
   // Corresponds exactly to a Java volatile load.
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 0abea9f..035cead 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -14,12 +14,6 @@
  * limitations under the License.
  */
 
-// Disable optimizations for Atomic::LoadJavaData on x86 devices.
-// Bug: http://b/34287931
-#if defined(__i386__)
-#define DISABLE_LOAD_JAVA_DATA_OPTIMIZATIONS
-#endif
-
 #include "class_linker.h"
 
 #include <algorithm>