Merge "Check that the String class is not movable in String.equals intrinsics."

1 files changed, 8 insertions, 0 deletions

diff --git a/compiler/optimizing/intrinsics_arm_vixl.cc b/compiler/optimizing/intrinsics_arm_vixl.cc
index 396ff62a16..f0aa92e981 100644
--- a/compiler/optimizing/intrinsics_arm_vixl.cc
+++ b/compiler/optimizing/intrinsics_arm_vixl.cc
@@ -1529,8 +1529,16 @@ void IntrinsicCodeGeneratorARMVIXL::VisitStringEquals(HInvoke* invoke) {
     // All string objects must have the same type since String cannot be subclassed.
     // Receiver must be a string object, so its class field is equal to all strings' class fields.
     // If the argument is a string object, its class field must be equal to receiver's class field.
+    //
+    // As the String class is expected to be non-movable, we can read the class
+    // field from String.equals' arguments without read barriers.
+    AssertNonMovableStringClass();
+    // /* HeapReference<Class> */ temp = str->klass_
     __ Ldr(temp, MemOperand(str, class_offset));
+    // /* HeapReference<Class> */ out = arg->klass_
     __ Ldr(out, MemOperand(arg, class_offset));
+    // Also, because we use the previously loaded class references only in the
+    // following comparison, we don't need to unpoison them.
     __ Cmp(temp, out);
     __ B(ne, &return_false, /* is_far_target= */ false);
   }