ARM: Don't generate memory instructions with writeback where the data and address registers are the…

runtime/vm/assembler_arm.h

Index: runtime/vm/assembler_arm.h
diff --git a/runtime/vm/assembler_arm.h b/runtime/vm/assembler_arm.h
index 349a50e672956d7d07ed38676a49e45d41bf686c..80b888bc62e248afb71a9209927257463713d5f8 100644
--- a/runtime/vm/assembler_arm.h
+++ b/runtime/vm/assembler_arm.h
@@ -321,6 +321,11 @@ class Address : public ValueObject {
 
   Mode mode() const { return static_cast<Mode>(encoding() & kModeMask); }
 
+  bool has_writeback() const {
+    return (mode() == PreIndex) || (mode() == PostIndex) ||
+           (mode() == NegPreIndex) || (mode() == NegPostIndex);
+  }
+
   uint32_t encoding() const { return encoding_; }
 
   // Encoding for addressing mode 3.