Generalized division via multiplication.

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/base/bits.h"
+#include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
 #include "src/cpu-profiler.h"
 #include "src/debug.h"
 #include "src/isolate-inl.h"
 #include "src/runtime.h"
 
 namespace v8 {
 namespace internal {
 
@@ skipping 5305 matching lines @@
          isolate->code_aging_helper()->IsOld(sequence));
   return is_young;
 }
 
 
 void MacroAssembler::TruncatingDiv(Register result,
                                    Register dividend,
                                    int32_t divisor) {
   DCHECK(!AreAliased(result, dividend));
   DCHECK(result.Is32Bits() && dividend.Is32Bits());
-  MultiplierAndShift ms(divisor);
-  Mov(result, ms.multiplier());
+  base::MagicNumbersForDivision<uint32_t> mag =
+      base::SignedDivisionByConstant(static_cast<uint32_t>(divisor));
+  Mov(result, mag.multiplier);
   Smull(result.X(), dividend, result);
   Asr(result.X(), result.X(), 32);
-  if (divisor > 0 && ms.multiplier() < 0) Add(result, result, dividend);
-  if (divisor < 0 && ms.multiplier() > 0) Sub(result, result, dividend);
-  if (ms.shift() > 0) Asr(result, result, ms.shift());
+  bool neg = (mag.multiplier & (static_cast<uint32_t>(1) << 31)) != 0;
+  if (divisor > 0 && neg) Add(result, result, dividend);
+  if (divisor < 0 && !neg && mag.multiplier > 0) Sub(result, result, dividend);
+  if (mag.shift > 0) Asr(result, result, mag.shift);
   Add(result, result, Operand(dividend, LSR, 31));
 }
 
 
 #undef __
 
 
 UseScratchRegisterScope::~UseScratchRegisterScope() {
   available_->set_list(old_available_);
   availablefp_->set_list(old_availablefp_);
@@ skipping 73 matching lines @@
   }
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64