MIPS: Generalized division via multiplication.

src/mips64/macro-assembler-mips64.cc

 // Copyright 2012 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 <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_MIPS64
 
+#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 6062 matching lines @@
   masm_.emit(instr);
 }
 
 
 void MacroAssembler::TruncatingDiv(Register result,
                                    Register dividend,
                                    int32_t divisor) {
   DCHECK(!dividend.is(result));
   DCHECK(!dividend.is(at));
   DCHECK(!result.is(at));
-  MultiplierAndShift ms(divisor);
-  li(at, Operand(ms.multiplier()));
+  base::MagicNumbersForDivision<uint32_t> mag =
+  base::SignedDivisionByConstant(static_cast<uint32_t>(divisor));
+  li(at, Operand(mag.multiplier));
   Mulh(result, dividend, Operand(at));
-  if (divisor > 0 && ms.multiplier() < 0) {
+  bool neg = (mag.multiplier & (static_cast<uint32_t>(1) << 31)) != 0;
+  if (divisor > 0 && neg) {
     Addu(result, result, Operand(dividend));
   }
-  if (divisor < 0 && ms.multiplier() > 0) {
+  if (divisor < 0 && !neg && mag.multiplier > 0) {
     Subu(result, result, Operand(dividend));
   }
-  if (ms.shift() > 0) sra(result, result, ms.shift());
+  if (mag.shift > 0) sra(result, result, mag.shift);
   srl(at, dividend, 31);
   Addu(result, result, Operand(at));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_MIPS64