Fix FlooringDivByPowerOf2I on ARM/ARM64

src/arm/lithium-codegen-arm.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 "v8.h"
 
 #include "arm/lithium-codegen-arm.h"
 #include "arm/lithium-gap-resolver-arm.h"
 #include "code-stubs.h"
 #include "stub-cache.h"
@@ skipping 1417 matching lines @@
 
   __ vmls(minuend, multiplier, multiplicand);
 }
 
 
 void LCodeGen::DoFlooringDivByPowerOf2I(LFlooringDivByPowerOf2I* instr) {
   Register dividend = ToRegister(instr->dividend());
   Register result = ToRegister(instr->result());
   int32_t divisor = instr->divisor();
 
+  // If the divisor is 1, return the dividend.
+  if (divisor == 1) {
+    __ Move(result, dividend);
+    return;
+  }
+
   // If the divisor is positive, things are easy: There can be no deopts and we
   // can simply do an arithmetic right shift.
-  if (divisor == 1) return;
   int32_t shift = WhichPowerOf2Abs(divisor);
   if (divisor > 1) {
     __ mov(result, Operand(dividend, ASR, shift));
     return;
   }
 
   // If the divisor is negative, we have to negate and handle edge cases.
   __ rsb(result, dividend, Operand::Zero(), SetCC);
   if (instr->hydrogen()->CheckFlag(HValue::kBailoutOnMinusZero)) {
     DeoptimizeIf(eq, instr->environment());
@@ skipping 4402 matching lines @@
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal