Use (more) xor on FP register to load it with 0.0.

runtime/vm/intermediate_language_arm64.cc

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_ARM64.
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 278 matching lines @@
   const intptr_t kNumInputs = 0;
   return LocationSummary::Make(isolate,
                                kNumInputs,
                                Location::RequiresFpuRegister(),
                                LocationSummary::kNoCall);
 }
 
 
 void UnboxedConstantInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   if (!locs()->out(0).IsInvalid()) {
-    const VRegister dst = locs()->out(0).fpu_reg();
-    __ LoadDImmediate(dst, Double::Cast(value()).value(), PP);
+    if (Utils::DoublesBitEqual(Double::Cast(value()).value(), 0.0)) {
+      const VRegister dst = locs()->out(0).fpu_reg();
+      __ veor(dst, dst, dst);
+    } else {
+      const VRegister dst = locs()->out(0).fpu_reg();
+      __ LoadDImmediate(dst, Double::Cast(value()).value(), PP);
+    }
   }
 }
 
 
 LocationSummary* AssertAssignableInstr::MakeLocationSummary(Isolate* isolate,
                                                             bool opt) const {
   const intptr_t kNumInputs = 3;
   const intptr_t kNumTemps = 0;
   LocationSummary* summary = new(isolate) LocationSummary(
       isolate, kNumInputs, kNumTemps, LocationSummary::kCall);
@@ skipping 5001 matching lines @@
   compiler->GenerateCall(token_pos(), &label, stub_kind_, locs());
 #if defined(DEBUG)
   __ LoadImmediate(R4, kInvalidObjectPointer, kNoPP);
   __ LoadImmediate(R5, kInvalidObjectPointer, kNoPP);
 #endif
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64