A64: Implement LMathFloorOfDiv and enable the instruction in hydrogen

src/hydrogen-instructions.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1508 matching lines @@
     // with its input. This happens before the representation changes are
     // introduced.
 
     // TODO(2205): The above comment is lying. All of this happens
     // *after* representation changes are introduced. We should check
     // for value->IsChange() and react accordingly if yes.
 
     if (value()->representation().IsInteger32()) return value();
 
 #if defined(V8_TARGET_ARCH_ARM) || defined(V8_TARGET_ARCH_IA32) || \
-        defined(V8_TARGET_ARCH_X64)
+        defined(V8_TARGET_ARCH_X64) || defined(V8_TARGET_ARCH_A64)
     if (value()->IsDiv() && (value()->UseCount() == 1)) {
       // TODO(2038): Implement this optimization for non ARM architectures.
       HDiv* hdiv = HDiv::cast(value());
       HValue* left = hdiv->left();
       HValue* right = hdiv->right();
       // Try to simplify left and right values of the division.
       HValue* new_left =
         LChunkBuilder::SimplifiedDividendForMathFloorOfDiv(left);
       HValue* new_right =
         LChunkBuilder::SimplifiedDivisorForMathFloorOfDiv(right);
@@ skipping 2317 matching lines @@
     case kBackingStore:
       if (!name_.is_null()) stream->Add(*String::cast(*name_)->ToCString());
       stream->Add("[backing-store]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal