/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "intrinsics_mips.h"

#include "arch/mips/instruction_set_features_mips.h"
#include "art_method.h"
#include "code_generator_mips.h"
#include "entrypoints/quick/quick_entrypoints.h"
#include "intrinsics.h"
#include "mirror/array-inl.h"
#include "mirror/string.h"
#include "thread.h"
#include "utils/mips/assembler_mips.h"
#include "utils/mips/constants_mips.h"

namespace art {

namespace mips {

IntrinsicLocationsBuilderMIPS::IntrinsicLocationsBuilderMIPS(CodeGeneratorMIPS* codegen)
  : arena_(codegen->GetGraph()->GetArena()) {
}

MipsAssembler* IntrinsicCodeGeneratorMIPS::GetAssembler() {
  return reinterpret_cast<MipsAssembler*>(codegen_->GetAssembler());
}

ArenaAllocator* IntrinsicCodeGeneratorMIPS::GetAllocator() {
  return codegen_->GetGraph()->GetArena();
}

#define __ codegen->GetAssembler()->

static void MoveFromReturnRegister(Location trg,
                                   Primitive::Type type,
                                   CodeGeneratorMIPS* codegen) {
  if (!trg.IsValid()) {
    DCHECK_EQ(type, Primitive::kPrimVoid);
    return;
  }

  DCHECK_NE(type, Primitive::kPrimVoid);

  if (Primitive::IsIntegralType(type) || type == Primitive::kPrimNot) {
    Register trg_reg = trg.AsRegister<Register>();
    if (trg_reg != V0) {
      __ Move(V0, trg_reg);
    }
  } else {
    FRegister trg_reg = trg.AsFpuRegister<FRegister>();
    if (trg_reg != F0) {
      if (type == Primitive::kPrimFloat) {
        __ MovS(F0, trg_reg);
      } else {
        __ MovD(F0, trg_reg);
      }
    }
  }
}

static void MoveArguments(HInvoke* invoke, CodeGeneratorMIPS* codegen) {
  InvokeDexCallingConventionVisitorMIPS calling_convention_visitor;
  IntrinsicVisitor::MoveArguments(invoke, codegen, &calling_convention_visitor);
}

// Slow-path for fallback (calling the managed code to handle the
// intrinsic) in an intrinsified call. This will copy the arguments
// into the positions for a regular call.
//
// Note: The actual parameters are required to be in the locations
//       given by the invoke's location summary. If an intrinsic
//       modifies those locations before a slowpath call, they must be
//       restored!
class IntrinsicSlowPathMIPS : public SlowPathCodeMIPS {
 public:
  explicit IntrinsicSlowPathMIPS(HInvoke* invoke) : invoke_(invoke) { }

  void EmitNativeCode(CodeGenerator* codegen_in) OVERRIDE {
    CodeGeneratorMIPS* codegen = down_cast<CodeGeneratorMIPS*>(codegen_in);

    __ Bind(GetEntryLabel());

    SaveLiveRegisters(codegen, invoke_->GetLocations());

    MoveArguments(invoke_, codegen);

    if (invoke_->IsInvokeStaticOrDirect()) {
      codegen->GenerateStaticOrDirectCall(invoke_->AsInvokeStaticOrDirect(),
                                          Location::RegisterLocation(A0));
      codegen->RecordPcInfo(invoke_, invoke_->GetDexPc(), this);
    } else {
      UNIMPLEMENTED(FATAL) << "Non-direct intrinsic slow-path not yet implemented";
      UNREACHABLE();
    }

    // Copy the result back to the expected output.
    Location out = invoke_->GetLocations()->Out();
    if (out.IsValid()) {
      DCHECK(out.IsRegister());  // TODO: Replace this when we support output in memory.
      DCHECK(!invoke_->GetLocations()->GetLiveRegisters()->ContainsCoreRegister(out.reg()));
      MoveFromReturnRegister(out, invoke_->GetType(), codegen);
    }

    RestoreLiveRegisters(codegen, invoke_->GetLocations());
    __ B(GetExitLabel());
  }

  const char* GetDescription() const OVERRIDE { return "IntrinsicSlowPathMIPS"; }

 private:
  // The instruction where this slow path is happening.
  HInvoke* const invoke_;

  DISALLOW_COPY_AND_ASSIGN(IntrinsicSlowPathMIPS);
};

#undef __

bool IntrinsicLocationsBuilderMIPS::TryDispatch(HInvoke* invoke) {
  Dispatch(invoke);
  LocationSummary* res = invoke->GetLocations();
  return res != nullptr && res->Intrinsified();
}

#define __ assembler->

// boolean java.lang.String.equals(Object anObject)
void IntrinsicLocationsBuilderMIPS::VisitStringEquals(HInvoke* invoke) {
  LocationSummary* locations = new (arena_) LocationSummary(invoke,
                                                            LocationSummary::kNoCall,
                                                            kIntrinsified);
  locations->SetInAt(0, Location::RequiresRegister());
  locations->SetInAt(1, Location::RequiresRegister());
  locations->SetOut(Location::RequiresRegister());

  // Temporary registers to store lengths of strings and for calculations.
  locations->AddTemp(Location::RequiresRegister());
  locations->AddTemp(Location::RequiresRegister());
  locations->AddTemp(Location::RequiresRegister());
}

void IntrinsicCodeGeneratorMIPS::VisitStringEquals(HInvoke* invoke) {
  MipsAssembler* assembler = GetAssembler();
  LocationSummary* locations = invoke->GetLocations();

  Register str = locations->InAt(0).AsRegister<Register>();
  Register arg = locations->InAt(1).AsRegister<Register>();
  Register out = locations->Out().AsRegister<Register>();

  Register temp1 = locations->GetTemp(0).AsRegister<Register>();
  Register temp2 = locations->GetTemp(1).AsRegister<Register>();
  Register temp3 = locations->GetTemp(2).AsRegister<Register>();

  MipsLabel loop;
  MipsLabel end;
  MipsLabel return_true;
  MipsLabel return_false;

  // Get offsets of count, value, and class fields within a string object.
  const uint32_t count_offset = mirror::String::CountOffset().Uint32Value();
  const uint32_t value_offset = mirror::String::ValueOffset().Uint32Value();
  const uint32_t class_offset = mirror::Object::ClassOffset().Uint32Value();

  // Note that the null check must have been done earlier.
  DCHECK(!invoke->CanDoImplicitNullCheckOn(invoke->InputAt(0)));

  // If the register containing the pointer to "this", and the register
  // containing the pointer to "anObject" are the same register then
  // "this", and "anObject" are the same object and we can
  // short-circuit the logic to a true result.
  if (str == arg) {
    __ LoadConst32(out, 1);
    return;
  }

  // Check if input is null, return false if it is.
  __ Beqz(arg, &return_false);

  // Reference equality check, return true if same reference.
  __ Beq(str, arg, &return_true);

  // Instanceof check for the argument by comparing class fields.
  // All string objects must have the same type since String cannot be subclassed.
  // Receiver must be a string object, so its class field is equal to all strings' class fields.
  // If the argument is a string object, its class field must be equal to receiver's class field.
  __ Lw(temp1, str, class_offset);
  __ Lw(temp2, arg, class_offset);
  __ Bne(temp1, temp2, &return_false);

  // Load lengths of this and argument strings.
  __ Lw(temp1, str, count_offset);
  __ Lw(temp2, arg, count_offset);
  // Check if lengths are equal, return false if they're not.
  __ Bne(temp1, temp2, &return_false);
  // Return true if both strings are empty.
  __ Beqz(temp1, &return_true);

  // Don't overwrite input registers
  __ Move(TMP, str);
  __ Move(temp3, arg);

  // Assertions that must hold in order to compare strings 2 characters at a time.
  DCHECK_ALIGNED(value_offset, 4);
  static_assert(IsAligned<4>(kObjectAlignment), "String of odd length is not zero padded");

  // Loop to compare strings 2 characters at a time starting at the beginning of the string.
  // Ok to do this because strings are zero-padded.
  __ Bind(&loop);
  __ Lw(out, TMP, value_offset);
  __ Lw(temp2, temp3, value_offset);
  __ Bne(out, temp2, &return_false);
  __ Addiu(TMP, TMP, 4);
  __ Addiu(temp3, temp3, 4);
  __ Addiu(temp1, temp1, -2);
  __ Bgtz(temp1, &loop);

  // Return true and exit the function.
  // If loop does not result in returning false, we return true.
  __ Bind(&return_true);
  __ LoadConst32(out, 1);
  __ B(&end);

  // Return false and exit the function.
  __ Bind(&return_false);
  __ LoadConst32(out, 0);
  __ Bind(&end);
}

// Unimplemented intrinsics.

#define UNIMPLEMENTED_INTRINSIC(Name)                                                  \
void IntrinsicLocationsBuilderMIPS::Visit ## Name(HInvoke* invoke ATTRIBUTE_UNUSED) { \
}                                                                                      \
void IntrinsicCodeGeneratorMIPS::Visit ## Name(HInvoke* invoke ATTRIBUTE_UNUSED) {    \
}

UNIMPLEMENTED_INTRINSIC(IntegerReverse)
UNIMPLEMENTED_INTRINSIC(LongReverse)
UNIMPLEMENTED_INTRINSIC(ShortReverseBytes)
UNIMPLEMENTED_INTRINSIC(IntegerReverseBytes)
UNIMPLEMENTED_INTRINSIC(LongReverseBytes)
UNIMPLEMENTED_INTRINSIC(LongNumberOfLeadingZeros)
UNIMPLEMENTED_INTRINSIC(IntegerNumberOfLeadingZeros)
UNIMPLEMENTED_INTRINSIC(FloatIntBitsToFloat)
UNIMPLEMENTED_INTRINSIC(DoubleLongBitsToDouble)
UNIMPLEMENTED_INTRINSIC(FloatFloatToRawIntBits)
UNIMPLEMENTED_INTRINSIC(DoubleDoubleToRawLongBits)
UNIMPLEMENTED_INTRINSIC(MathAbsDouble)
UNIMPLEMENTED_INTRINSIC(MathAbsFloat)
UNIMPLEMENTED_INTRINSIC(MathAbsInt)
UNIMPLEMENTED_INTRINSIC(MathAbsLong)
UNIMPLEMENTED_INTRINSIC(MathMinDoubleDouble)
UNIMPLEMENTED_INTRINSIC(MathMinFloatFloat)
UNIMPLEMENTED_INTRINSIC(MathMaxDoubleDouble)
UNIMPLEMENTED_INTRINSIC(MathMaxFloatFloat)
UNIMPLEMENTED_INTRINSIC(MathMinIntInt)
UNIMPLEMENTED_INTRINSIC(MathMinLongLong)
UNIMPLEMENTED_INTRINSIC(MathMaxIntInt)
UNIMPLEMENTED_INTRINSIC(MathMaxLongLong)
UNIMPLEMENTED_INTRINSIC(MathSqrt)
UNIMPLEMENTED_INTRINSIC(MathCeil)
UNIMPLEMENTED_INTRINSIC(MathFloor)
UNIMPLEMENTED_INTRINSIC(MathRint)
UNIMPLEMENTED_INTRINSIC(MathRoundDouble)
UNIMPLEMENTED_INTRINSIC(MathRoundFloat)
UNIMPLEMENTED_INTRINSIC(MemoryPeekByte)
UNIMPLEMENTED_INTRINSIC(MemoryPeekIntNative)
UNIMPLEMENTED_INTRINSIC(MemoryPeekLongNative)
UNIMPLEMENTED_INTRINSIC(MemoryPeekShortNative)
UNIMPLEMENTED_INTRINSIC(MemoryPokeByte)
UNIMPLEMENTED_INTRINSIC(MemoryPokeIntNative)
UNIMPLEMENTED_INTRINSIC(MemoryPokeLongNative)
UNIMPLEMENTED_INTRINSIC(MemoryPokeShortNative)
UNIMPLEMENTED_INTRINSIC(ThreadCurrentThread)
UNIMPLEMENTED_INTRINSIC(UnsafeGet)
UNIMPLEMENTED_INTRINSIC(UnsafeGetVolatile)
UNIMPLEMENTED_INTRINSIC(UnsafeGetLong)
UNIMPLEMENTED_INTRINSIC(UnsafeGetLongVolatile)
UNIMPLEMENTED_INTRINSIC(UnsafeGetObject)
UNIMPLEMENTED_INTRINSIC(UnsafeGetObjectVolatile)
UNIMPLEMENTED_INTRINSIC(UnsafePut)
UNIMPLEMENTED_INTRINSIC(UnsafePutOrdered)
UNIMPLEMENTED_INTRINSIC(UnsafePutVolatile)
UNIMPLEMENTED_INTRINSIC(UnsafePutObject)
UNIMPLEMENTED_INTRINSIC(UnsafePutObjectOrdered)
UNIMPLEMENTED_INTRINSIC(UnsafePutObjectVolatile)
UNIMPLEMENTED_INTRINSIC(UnsafePutLong)
UNIMPLEMENTED_INTRINSIC(UnsafePutLongOrdered)
UNIMPLEMENTED_INTRINSIC(UnsafePutLongVolatile)
UNIMPLEMENTED_INTRINSIC(UnsafeCASInt)
UNIMPLEMENTED_INTRINSIC(UnsafeCASLong)
UNIMPLEMENTED_INTRINSIC(UnsafeCASObject)
UNIMPLEMENTED_INTRINSIC(StringCharAt)
UNIMPLEMENTED_INTRINSIC(StringCompareTo)
UNIMPLEMENTED_INTRINSIC(StringIndexOf)
UNIMPLEMENTED_INTRINSIC(StringIndexOfAfter)
UNIMPLEMENTED_INTRINSIC(StringNewStringFromBytes)
UNIMPLEMENTED_INTRINSIC(StringNewStringFromChars)
UNIMPLEMENTED_INTRINSIC(StringNewStringFromString)
UNIMPLEMENTED_INTRINSIC(LongRotateLeft)
UNIMPLEMENTED_INTRINSIC(LongRotateRight)
UNIMPLEMENTED_INTRINSIC(LongNumberOfTrailingZeros)
UNIMPLEMENTED_INTRINSIC(IntegerRotateLeft)
UNIMPLEMENTED_INTRINSIC(IntegerRotateRight)
UNIMPLEMENTED_INTRINSIC(IntegerNumberOfTrailingZeros)

UNIMPLEMENTED_INTRINSIC(ReferenceGetReferent)
UNIMPLEMENTED_INTRINSIC(StringGetCharsNoCheck)
UNIMPLEMENTED_INTRINSIC(SystemArrayCopyChar)
UNIMPLEMENTED_INTRINSIC(SystemArrayCopy)

#undef UNIMPLEMENTED_INTRINSIC

#undef __

}  // namespace mips
}  // namespace art