x86/x64 port of Math.floor(x/y) to use integer division for specific divisor

src/ia32/lithium-ia32.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 1329 matching lines @@
     LOperand* divisor = UseRegister(instr->right());
     LDivI* result = new(zone()) LDivI(dividend, divisor, temp);
     return AssignEnvironment(DefineFixed(result, eax));
   } else {
     ASSERT(instr->representation().IsTagged());
     return DoArithmeticT(Token::DIV, instr);
   }
 }
 
 
+HValue* LChunkBuilder::SimplifiedDividendForMathFloorOfDiv(HValue* dividend) {
+  // A value with an integer representation does not need to be transformed.
+  if (dividend->representation().IsInteger32()) {
+    return dividend;
+  // A change from an integer32 can be replaced by the integer32 value.
+  } else if (dividend->IsChange() &&
+      HChange::cast(dividend)->from().IsInteger32()) {
+    return HChange::cast(dividend)->value();
+  }
+  return NULL;
+}
+
+
+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());
+  }
+  return NULL;
+}
+
+
 LInstruction* LChunkBuilder::DoMathFloorOfDiv(HMathFloorOfDiv* instr) {
-  UNIMPLEMENTED();
-  return NULL;
+  HValue* right = instr->right();
+  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))) {
+    // use dividend as temp if divisor < 0 && divisor != -1
+    LOperand* dividend = divisor_si < -1 ? UseTempRegister(instr->left()) :
+                         UseRegisterAtStart(instr->left());
+    LInstruction* result = DefineAsRegister(
+        new(zone()) LMathFloorOfDiv(dividend, divisor, NULL));
+    return divisor_si < 0 ? AssignEnvironment(result) : result;
+  } else {
+    // needs edx:eax, plus a temp
+    LOperand* dividend = UseFixed(instr->left(), eax);
+    LOperand* temp = TempRegister();
+    LInstruction* result = DefineFixed(
+        new(zone()) LMathFloorOfDiv(dividend, divisor, temp), edx);
+    return divisor_si < 0 ? AssignEnvironment(result) : result;
+  }
 }
 
 
 LInstruction* LChunkBuilder::DoMod(HMod* instr) {
   if (instr->representation().IsInteger32()) {
     ASSERT(instr->left()->representation().IsInteger32());
     ASSERT(instr->right()->representation().IsInteger32());
 
     LInstruction* result;
     if (instr->HasPowerOf2Divisor()) {
@@ skipping 1085 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_IA32