path: root/js/src/jit/mips32/Lowering-mips32.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "jit/mips32/Lowering-mips32.h"

#include "jit/Lowering.h"
#include "jit/mips32/Assembler-mips32.h"
#include "jit/MIR.h"

#include "jit/shared/Lowering-shared-inl.h"

using namespace js;
using namespace js::jit;

LBoxAllocation LIRGeneratorMIPS::useBoxFixed(MDefinition* mir, Register reg1,
                                             Register reg2, bool useAtStart) {
  MOZ_ASSERT(mir->type() == MIRType::Value);
  MOZ_ASSERT(reg1 != reg2);

  ensureDefined(mir);
  return LBoxAllocation(LUse(reg1, mir->virtualRegister(), useAtStart),
                        LUse(reg2, VirtualRegisterOfPayload(mir), useAtStart));
}

void LIRGenerator::visitBox(MBox* box) {
  MDefinition* inner = box->getOperand(0);

  // If the box wrapped a double, it needs a new register.
  if (IsFloatingPointType(inner->type())) {
    defineBox(new (alloc()) LBoxFloatingPoint(
                  useRegisterAtStart(inner), tempCopy(inner, 0), inner->type()),
              box);
    return;
  }

  if (box->canEmitAtUses()) {
    emitAtUses(box);
    return;
  }

  if (inner->isConstant()) {
    defineBox(new (alloc()) LValue(inner->toConstant()->toJSValue()), box);
    return;
  }

  LBox* lir = new (alloc()) LBox(use(inner), inner->type());

  // Otherwise, we should not define a new register for the payload portion
  // of the output, so bypass defineBox().
  uint32_t vreg = getVirtualRegister();

  // Note that because we're using BogusTemp(), we do not change the type of
  // the definition. We also do not define the first output as "TYPE",
  // because it has no corresponding payload at (vreg + 1). Also note that
  // although we copy the input's original type for the payload half of the
  // definition, this is only for clarity. BogusTemp() definitions are
  // ignored.
  lir->setDef(0, LDefinition(vreg, LDefinition::GENERAL));
  lir->setDef(1, LDefinition::BogusTemp());
  box->setVirtualRegister(vreg);
  add(lir);
}

void LIRGenerator::visitUnbox(MUnbox* unbox) {
  MDefinition* inner = unbox->getOperand(0);

  // An unbox on mips reads in a type tag (either in memory or a register) and
  // a payload. Unlike most instructions consuming a box, we ask for the type
  // second, so that the result can re-use the first input.
  MOZ_ASSERT(inner->type() == MIRType::Value);

  ensureDefined(inner);

  if (IsFloatingPointType(unbox->type())) {
    LUnboxFloatingPoint* lir =
        new (alloc()) LUnboxFloatingPoint(useBox(inner), unbox->type());
    if (unbox->fallible()) {
      assignSnapshot(lir, unbox->bailoutKind());
    }
    define(lir, unbox);
    return;
  }

  // Swap the order we use the box pieces so we can re-use the payload
  // register.
  LUnbox* lir = new (alloc()) LUnbox;
  lir->setOperand(0, usePayloadInRegisterAtStart(inner));
  lir->setOperand(1, useType(inner, LUse::REGISTER));

  if (unbox->fallible()) {
    assignSnapshot(lir, unbox->bailoutKind());
  }

  // Types and payloads form two separate intervals. If the type becomes dead
  // before the payload, it could be used as a Value without the type being
  // recoverable. Unbox's purpose is to eagerly kill the definition of a type
  // tag, so keeping both alive (for the purpose of gcmaps) is unappealing.
  // Instead, we create a new virtual register.
  defineReuseInput(lir, unbox, 0);
}

void LIRGenerator::visitReturnImpl(MDefinition* opd, bool isGenerator) {
  MOZ_ASSERT(opd->type() == MIRType::Value);

  LReturn* ins = new (alloc()) LReturn(isGenerator);
  ins->setOperand(0, LUse(JSReturnReg_Type));
  ins->setOperand(1, LUse(JSReturnReg_Data));
  fillBoxUses(ins, 0, opd);
  add(ins);
}

void LIRGeneratorMIPS::lowerUntypedPhiInput(MPhi* phi, uint32_t inputPosition,
                                            LBlock* block, size_t lirIndex) {
  MDefinition* operand = phi->getOperand(inputPosition);
  LPhi* type = block->getPhi(lirIndex + VREG_TYPE_OFFSET);
  LPhi* payload = block->getPhi(lirIndex + VREG_DATA_OFFSET);
  type->setOperand(
      inputPosition,
      LUse(operand->virtualRegister() + VREG_TYPE_OFFSET, LUse::ANY));
  payload->setOperand(inputPosition,
                      LUse(VirtualRegisterOfPayload(operand), LUse::ANY));
}

void LIRGeneratorMIPS::defineInt64Phi(MPhi* phi, size_t lirIndex) {
  LPhi* low = current->getPhi(lirIndex + INT64LOW_INDEX);
  LPhi* high = current->getPhi(lirIndex + INT64HIGH_INDEX);

  uint32_t lowVreg = getVirtualRegister();

  phi->setVirtualRegister(lowVreg);

  uint32_t highVreg = getVirtualRegister();
  MOZ_ASSERT(lowVreg + INT64HIGH_INDEX == highVreg + INT64LOW_INDEX);

  low->setDef(0, LDefinition(lowVreg, LDefinition::INT32));
  high->setDef(0, LDefinition(highVreg, LDefinition::INT32));
  annotate(high);
  annotate(low);
}

void LIRGeneratorMIPS::lowerInt64PhiInput(MPhi* phi, uint32_t inputPosition,
                                          LBlock* block, size_t lirIndex) {
  MDefinition* operand = phi->getOperand(inputPosition);
  LPhi* low = block->getPhi(lirIndex + INT64LOW_INDEX);
  LPhi* high = block->getPhi(lirIndex + INT64HIGH_INDEX);
  low->setOperand(inputPosition,
                  LUse(operand->virtualRegister() + INT64LOW_INDEX, LUse::ANY));
  high->setOperand(
      inputPosition,
      LUse(operand->virtualRegister() + INT64HIGH_INDEX, LUse::ANY));
}

void LIRGeneratorMIPS::lowerTruncateDToInt32(MTruncateToInt32* ins) {
  MDefinition* opd = ins->input();
  MOZ_ASSERT(opd->type() == MIRType::Double);

  define(new (alloc())
             LTruncateDToInt32(useRegister(opd), LDefinition::BogusTemp()),
         ins);
}

void LIRGeneratorMIPS::lowerTruncateFToInt32(MTruncateToInt32* ins) {
  MDefinition* opd = ins->input();
  MOZ_ASSERT(opd->type() == MIRType::Float32);

  define(new (alloc())
             LTruncateFToInt32(useRegister(opd), LDefinition::BogusTemp()),
         ins);
}

void LIRGeneratorMIPS::lowerDivI64(MDiv* div) {
  if (div->isUnsigned()) {
    lowerUDivI64(div);
    return;
  }

  LDivOrModI64* lir = new (alloc()) LDivOrModI64(
      useInt64RegisterAtStart(div->lhs()), useInt64RegisterAtStart(div->rhs()));

  defineReturn(lir, div);
}

void LIRGeneratorMIPS::lowerWasmBuiltinDivI64(MWasmBuiltinDivI64* div) {
  MOZ_CRASH("We don't use runtime div for this architecture");
}

void LIRGeneratorMIPS::lowerModI64(MMod* mod) {
  if (mod->isUnsigned()) {
    lowerUModI64(mod);
    return;
  }

  LDivOrModI64* lir = new (alloc()) LDivOrModI64(
      useInt64RegisterAtStart(mod->lhs()), useInt64RegisterAtStart(mod->rhs()));

  defineReturn(lir, mod);
}

void LIRGeneratorMIPS::lowerWasmBuiltinModI64(MWasmBuiltinModI64* mod) {
  MOZ_CRASH("We don't use runtime mod for this architecture");
}

void LIRGeneratorMIPS::lowerUDivI64(MDiv* div) {
  LUDivOrModI64* lir = new (alloc()) LUDivOrModI64(
      useInt64RegisterAtStart(div->lhs()), useInt64RegisterAtStart(div->rhs()));
  defineReturn(lir, div);
}

void LIRGeneratorMIPS::lowerUModI64(MMod* mod) {
  LUDivOrModI64* lir = new (alloc()) LUDivOrModI64(
      useInt64RegisterAtStart(mod->lhs()), useInt64RegisterAtStart(mod->rhs()));
  defineReturn(lir, mod);
}

void LIRGeneratorMIPS::lowerBigIntDiv(MBigIntDiv* ins) {
  auto* lir = new (alloc()) LBigIntDiv(useRegister(ins->lhs()),
                                       useRegister(ins->rhs()), temp(), temp());
  define(lir, ins);
  assignSafepoint(lir, ins);
}

void LIRGeneratorMIPS::lowerBigIntMod(MBigIntMod* ins) {
  auto* lir = new (alloc()) LBigIntMod(useRegister(ins->lhs()),
                                       useRegister(ins->rhs()), temp(), temp());
  define(lir, ins);
  assignSafepoint(lir, ins);
}

void LIRGenerator::visitWasmTruncateToInt64(MWasmTruncateToInt64* ins) {
  MDefinition* opd = ins->input();
  MOZ_ASSERT(opd->type() == MIRType::Double || opd->type() == MIRType::Float32);

  defineReturn(new (alloc()) LWasmTruncateToInt64(useRegisterAtStart(opd)),
               ins);
}

void LIRGeneratorMIPS::lowerWasmBuiltinTruncateToInt64(
    MWasmBuiltinTruncateToInt64* ins) {
  MOZ_CRASH("We don't use it for this architecture");
}

void LIRGenerator::visitInt64ToFloatingPoint(MInt64ToFloatingPoint* ins) {
  MDefinition* opd = ins->input();
  MOZ_ASSERT(opd->type() == MIRType::Int64);
  MOZ_ASSERT(IsFloatingPointType(ins->type()));

  defineReturn(
      new (alloc()) LInt64ToFloatingPoint(useInt64RegisterAtStart(opd)), ins);
}

void LIRGeneratorMIPS::lowerBuiltinInt64ToFloatingPoint(
    MBuiltinInt64ToFloatingPoint* ins) {
  MOZ_CRASH("We don't use it for this architecture");
}