ARM64: improve Adr patching

src/arm64/macro-assembler-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 595 matching lines @@
 void MacroAssembler::Adr(const Register& rd, Label* label, AdrHint hint) {
   ASSERT(allow_macro_instructions_);
   ASSERT(!rd.IsZero());
 
   if (hint == kAdrNear) {
     adr(rd, label);
     return;
   }
 
   ASSERT(hint == kAdrFar);
-  UseScratchRegisterScope temps(this);
-  Register scratch = temps.AcquireX();
-  ASSERT(!AreAliased(rd, scratch));
-
   if (label->is_bound()) {
     int label_offset = label->pos() - pc_offset();
     if (Instruction::IsValidPCRelOffset(label_offset)) {
       adr(rd, label);
     } else {
       ASSERT(label_offset <= 0);
       int min_adr_offset = -(1 << (Instruction::ImmPCRelRangeBitwidth - 1));
       adr(rd, min_adr_offset);
       Add(rd, rd, label_offset - min_adr_offset);
     }
   } else {
+    UseScratchRegisterScope temps(this);
+    Register scratch = temps.AcquireX();
+
     InstructionAccurateScope scope(
         this, PatchingAssembler::kAdrFarPatchableNInstrs);
     adr(rd, label);
     for (int i = 0; i < PatchingAssembler::kAdrFarPatchableNNops; ++i) {
       nop(ADR_FAR_NOP);
     }
     movz(scratch, 0);
-    add(rd, rd, scratch);
   }
 }
 
 
 void MacroAssembler::B(Label* label, BranchType type, Register reg, int bit) {
   ASSERT((reg.Is(NoReg) || type >= kBranchTypeFirstUsingReg) &&
          (bit == -1 || type >= kBranchTypeFirstUsingBit));
   if (kBranchTypeFirstCondition <= type && type <= kBranchTypeLastCondition) {
     B(static_cast<Condition>(type), label);
   } else {
@@ skipping 4666 matching lines @@
   }
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64