VM: Improve loading of large immediates on ARM64.

runtime/vm/assembler_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"  // NOLINT
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/longjump.h"
@@ skipping 475 matching lines @@
   movz(reg, Immediate(h0), 0);
   movk(reg, Immediate(h1), 1);
   movk(reg, Immediate(h2), 2);
   movk(reg, Immediate(h3), 3);
 }
 
 
 void Assembler::LoadImmediate(Register reg, int64_t imm, Register pp) {
   Comment("LoadImmediate");
   if (CanLoadImmediateFromPool(imm, pp)) {
-    // It's a 64-bit constant and we're not in the VM isolate, so load from
-    // object pool.
-    // Save the bits that must be masked-off for the SmiTag
-    int64_t val_smi_tag = imm & kSmiTagMask;
-    imm &= ~kSmiTagMask;  // Mask off the tag bits.
     const int32_t offset = ObjectPool::element_offset(FindImmediate(imm));
     LoadWordFromPoolOffset(reg, pp, offset);
-    if (val_smi_tag != 0) {
-      // Add back the tag bits.
-      orri(reg, reg, Immediate(val_smi_tag));
-    }
   } else {
     // 0. Is it 0?
     if (imm == 0) {
       movz(reg, Immediate(0), 0);
       return;
     }
 
     // 1. Can we use one orri operation?
     Operand op;
     Operand::OperandType ot;
@@ skipping 940 matching lines @@
     add(base, array, Operand(index, LSL, shift));
   }
   const OperandSize size = Address::OperandSizeFor(cid);
   ASSERT(Address::CanHoldOffset(offset, Address::Offset, size));
   return Address(base, offset, Address::Offset, size);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64