Implement flooring division by a constant via truncating division by a constant.

src/a64/lithium-a64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
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@@ skipping 1744 matching lines @@
   return result;
 }
 
 
 LInstruction* LChunkBuilder::DoFlooringDivByConstI(HMathFloorOfDiv* instr) {
   ASSERT(instr->representation().IsInteger32());
   ASSERT(instr->left()->representation().Equals(instr->representation()));
   ASSERT(instr->right()->representation().Equals(instr->representation()));
   LOperand* dividend = UseRegister(instr->left());
   int32_t divisor = instr->right()->GetInteger32Constant();
-  LInstruction* result =
-      DefineAsRegister(new(zone()) LFlooringDivByConstI(dividend, divisor));
-  bool can_deopt =
-      divisor == 0 ||
-      (instr->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0);
-  return can_deopt ? AssignEnvironment(result) : result;
+  LOperand* temp =
+      ((divisor > 0 && !instr->CheckFlag(HValue::kLeftCanBeNegative)) ||
+       (divisor < 0 && !instr->CheckFlag(HValue::kLeftCanBePositive))) ?
+      NULL : TempRegister();
+  LInstruction* result = DefineAsRegister(
+      new(zone()) LFlooringDivByConstI(dividend, divisor, temp));
+  if (divisor == 0 ||
+      (instr->CheckFlag(HValue::kBailoutOnMinusZero) && divisor < 0)) {
+    result = AssignEnvironment(result);
+  }
+  return result;
 }
 
 
 LInstruction* LChunkBuilder::DoFlooringDivI(HMathFloorOfDiv* instr) {
   LOperand* dividend = UseRegister(instr->left());
   LOperand* divisor = UseRegister(instr->right());
   LOperand* remainder = TempRegister();
   LInstruction* result =
       DefineAsRegister(new(zone()) LFlooringDivI(dividend, divisor, remainder));
   return AssignEnvironment(result);
 }
 
 
 LInstruction* LChunkBuilder::DoMathFloorOfDiv(HMathFloorOfDiv* instr) {
   if (instr->RightIsPowerOf2()) {
     return DoFlooringDivByPowerOf2I(instr);
-  } else if (false && instr->right()->IsConstant()) {
-    return DoFlooringDivByConstI(instr);  // TODO(svenpanne) Fix and re-enable.
+  } else if (instr->right()->IsConstant()) {
+    return DoFlooringDivByConstI(instr);
   } else {
     return DoFlooringDivI(instr);
   }
 }
 
 
 LInstruction* LChunkBuilder::DoMathMinMax(HMathMinMax* instr) {
   LOperand* left = NULL;
   LOperand* right = NULL;
   if (instr->representation().IsSmiOrInteger32()) {
@@ skipping 757 matching lines @@
 
 LInstruction* LChunkBuilder::DoWrapReceiver(HWrapReceiver* instr) {
   LOperand* receiver = UseRegister(instr->receiver());
   LOperand* function = UseRegister(instr->function());
   LWrapReceiver* result = new(zone()) LWrapReceiver(receiver, function);
   return AssignEnvironment(DefineAsRegister(result));
 }
 
 
 } }  // namespace v8::internal