Handle non-constant divisor in MathFloorOfDiv, on ia32/x64

src/x64/lithium-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1210 matching lines @@
 }
 
 
 HValue* LChunkBuilder::SimplifiedDivisorForMathFloorOfDiv(HValue* divisor) {
   if (divisor->IsConstant() &&
       HConstant::cast(divisor)->HasInteger32Value()) {
     HConstant* constant_val = HConstant::cast(divisor);
     return constant_val->CopyToRepresentation(Representation::Integer32(),
                                               divisor->block()->zone());
   }
+  // A value with an integer representation does not need to be transformed.
+  if (divisor->representation().IsInteger32())
+    return divisor;
+  // A change from an integer32 can be replaced by the integer32 value.
+  else if (divisor->IsChange() &&
+             HChange::cast(divisor)->from().IsInteger32())

[Yang, 2012/12/27 14:41:53]

Please indent the second line of the if-condition like we do in line 1226, and
add brackets for the if-body.

+    return HChange::cast(divisor)->value();
   return NULL;
 }
 
 
 LInstruction* LChunkBuilder::DoMathFloorOfDiv(HMathFloorOfDiv* instr) {
   HValue* right = instr->right();
+  if (!right->IsConstant()) {
+    ASSERT(right->representation().IsInteger32());
+    // The temporary operand is necessary to ensure that right is not allocated
+    // into rdx.
+    LOperand* temp = FixedTemp(rdx);
+    LOperand* dividend = UseFixed(instr->left(), rax);
+    LOperand* divisor = UseRegister(instr->right());
+    LDivI* flooring_div = new(zone()) LDivI(dividend, divisor, temp);
+    return AssignEnvironment(DefineFixed(flooring_div, rax));
+  }
+
   ASSERT(right->IsConstant() && HConstant::cast(right)->HasInteger32Value());
   LOperand* divisor = chunk_->DefineConstantOperand(HConstant::cast(right));
   int32_t divisor_si = HConstant::cast(right)->Integer32Value();
   if (divisor_si == 0) {
     LOperand* dividend = UseRegister(instr->left());
     return AssignEnvironment(DefineAsRegister(
         new(zone()) LMathFloorOfDiv(dividend, divisor, NULL)));
   } else if (IsPowerOf2(abs(divisor_si))) {
     LOperand* dividend = UseRegisterAtStart(instr->left());
     LInstruction* result = DefineAsRegister(
@@ skipping 1080 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64