Revert "Enable Load Store Elimination for ARM and ARM64"

On extended testing, I'm seeing a CHECK failure at utility_arm.cc:1201.

This reverts commit fcc36ba2a2b8fd10e6eebd21ecb6329606443ded.

Change-Id: Icae3d49cd7c8fcab09f2f989cbcb1d7e5c6d137a
diff --git a/compiler/dex/frontend.cc b/compiler/dex/frontend.cc
index bff7dff..51446f6 100644
--- a/compiler/dex/frontend.cc
+++ b/compiler/dex/frontend.cc
@@ -42,7 +42,7 @@
 
 /* Default optimizer/debug setting for the compiler. */
 static uint32_t kCompilerOptimizerDisableFlags = 0 |  // Disable specific optimizations
-  // (1 << kLoadStoreElimination) |
+  (1 << kLoadStoreElimination) |  // TODO: this pass has been broken for awhile - fix or delete.
   // (1 << kLoadHoisting) |
   // (1 << kSuppressLoads) |
   // (1 << kNullCheckElimination) |
@@ -96,12 +96,12 @@
     ~0U,
     // 1 = kArm, unused (will use kThumb2).
     ~0U,
-    // 2 = kArm64.
+    // 2 = kArm64.     TODO(Arm64): enable optimizations once backend is mature enough.
+    (1 << kLoadStoreElimination) |
     0,
     // 3 = kThumb2.
     0,
     // 4 = kX86.
-    (1 << kLoadStoreElimination) |
     0,
     // 5 = kX86_64.
     (1 << kLoadStoreElimination) |