/*
 * Copyright (C) 2011 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.
 */

/* This file contains x86-specific codegen factory support. */

namespace art {

bool genAddLong(CompilationUnit* cUnit, RegLocation rlDest,
                RegLocation rlSrc1, RegLocation rlSrc2)
{
  oatFlushAllRegs(cUnit);
  oatLockCallTemps(cUnit);  // Prepare for explicit register usage
  loadValueDirectWideFixed(cUnit, rlSrc1, r0, r1);
  loadValueDirectWideFixed(cUnit, rlSrc2, r2, r3);
  // Compute (r1:r0) = (r1:r0) + (r2:r3)
  opRegReg(cUnit, kOpAdd, r0, r2);  // r0 = r0 + r2
  opRegReg(cUnit, kOpAdc, r1, r3);  // r1 = r1 + r3 + CF
  RegLocation rlResult = {kLocPhysReg, 1, 0, 0, 0, 0, 0, 0, 1, r0, r1,
                          INVALID_SREG, INVALID_SREG};
  storeValueWide(cUnit, rlDest, rlResult);
  return false;
}

bool genSubLong(CompilationUnit* cUnit, RegLocation rlDest,
                RegLocation rlSrc1, RegLocation rlSrc2)
{
  oatFlushAllRegs(cUnit);
  oatLockCallTemps(cUnit);  // Prepare for explicit register usage
  loadValueDirectWideFixed(cUnit, rlSrc1, r0, r1);
  loadValueDirectWideFixed(cUnit, rlSrc2, r2, r3);
  // Compute (r1:r0) = (r1:r0) + (r2:r3)
  opRegReg(cUnit, kOpSub, r0, r2);  // r0 = r0 - r2
  opRegReg(cUnit, kOpSbc, r1, r3);  // r1 = r1 - r3 - CF
  RegLocation rlResult = {kLocPhysReg, 1, 0, 0, 0, 0, 0, 0, 1, r0, r1,
                          INVALID_SREG, INVALID_SREG};
  storeValueWide(cUnit, rlDest, rlResult);
  return false;
}

bool genAndLong(CompilationUnit* cUnit, RegLocation rlDest,
                RegLocation rlSrc1, RegLocation rlSrc2)
{
  oatFlushAllRegs(cUnit);
  oatLockCallTemps(cUnit);  // Prepare for explicit register usage
  loadValueDirectWideFixed(cUnit, rlSrc1, r0, r1);
  loadValueDirectWideFixed(cUnit, rlSrc2, r2, r3);
  // Compute (r1:r0) = (r1:r0) + (r2:r3)
  opRegReg(cUnit, kOpAnd, r0, r2);  // r0 = r0 - r2
  opRegReg(cUnit, kOpAnd, r1, r3);  // r1 = r1 - r3 - CF
  RegLocation rlResult = {kLocPhysReg, 1, 0, 0, 0, 0, 0, 0, 1, r0, r1,
                          INVALID_SREG, INVALID_SREG};
  storeValueWide(cUnit, rlDest, rlResult);
  return false;
}

bool genOrLong(CompilationUnit* cUnit, RegLocation rlDest,
               RegLocation rlSrc1, RegLocation rlSrc2)
{
  oatFlushAllRegs(cUnit);
  oatLockCallTemps(cUnit);  // Prepare for explicit register usage
  loadValueDirectWideFixed(cUnit, rlSrc1, r0, r1);
  loadValueDirectWideFixed(cUnit, rlSrc2, r2, r3);
  // Compute (r1:r0) = (r1:r0) + (r2:r3)
  opRegReg(cUnit, kOpOr, r0, r2);  // r0 = r0 - r2
  opRegReg(cUnit, kOpOr, r1, r3);  // r1 = r1 - r3 - CF
  RegLocation rlResult = {kLocPhysReg, 1, 0, 0, 0, 0, 0, 0, 1, r0, r1,
                          INVALID_SREG, INVALID_SREG};
  storeValueWide(cUnit, rlDest, rlResult);
  return false;
}

bool genXorLong(CompilationUnit* cUnit, RegLocation rlDest,
                RegLocation rlSrc1, RegLocation rlSrc2)
{
  oatFlushAllRegs(cUnit);
  oatLockCallTemps(cUnit);  // Prepare for explicit register usage
  loadValueDirectWideFixed(cUnit, rlSrc1, r0, r1);
  loadValueDirectWideFixed(cUnit, rlSrc2, r2, r3);
  // Compute (r1:r0) = (r1:r0) + (r2:r3)
  opRegReg(cUnit, kOpXor, r0, r2);  // r0 = r0 - r2
  opRegReg(cUnit, kOpXor, r1, r3);  // r1 = r1 - r3 - CF
  RegLocation rlResult = {kLocPhysReg, 1, 0, 0, 0, 0, 0, 0, 1, r0, r1,
                          INVALID_SREG, INVALID_SREG};
  storeValueWide(cUnit, rlDest, rlResult);
  return false;
}

bool genNegLong(CompilationUnit* cUnit, RegLocation rlDest,
                RegLocation rlSrc)
{
  oatFlushAllRegs(cUnit);
  oatLockCallTemps(cUnit);  // Prepare for explicit register usage
  loadValueDirectWideFixed(cUnit, rlSrc, r0, r1);
  // Compute (r1:r0) = -(r1:r0)
  opRegReg(cUnit, kOpNeg, r0, r0);  // r0 = -r0
  opRegImm(cUnit, kOpAdc, r1, 0);   // r1 = r1 + CF
  opRegReg(cUnit, kOpNeg, r1, r1);  // r1 = -r1
  RegLocation rlResult = {kLocPhysReg, 1, 0, 0, 0, 0, 0, 0, 1, r0, r1,
                          INVALID_SREG, INVALID_SREG};
  storeValueWide(cUnit, rlDest, rlResult);
  return false;
}

void spillCoreRegs(CompilationUnit* cUnit) {
  if (cUnit->numCoreSpills == 0) {
    return;
  }
  // Spill mask not including fake return address register
  uint32_t mask = cUnit->coreSpillMask & ~(1 << rRET);
  int offset = cUnit->frameSize - (4 * cUnit->numCoreSpills);
  for (int reg = 0; mask; mask >>= 1, reg++) {
    if (mask & 0x1) {
      storeWordDisp(cUnit, rSP, offset, reg);
      offset += 4;
    }
  }
}

void unSpillCoreRegs(CompilationUnit* cUnit) {
  if (cUnit->numCoreSpills == 0) {
    return;
  }
  // Spill mask not including fake return address register
  uint32_t mask = cUnit->coreSpillMask & ~(1 << rRET);
  int offset = cUnit->frameSize - (4 * cUnit->numCoreSpills);
  for (int reg = 0; mask; mask >>= 1, reg++) {
    if (mask & 0x1) {
      loadWordDisp(cUnit, rSP, offset, reg);
      offset += 4;
    }
  }
}

void opRegThreadMem(CompilationUnit* cUnit, OpKind op, int rDest, int threadOffset) {
  X86OpCode opcode = kX86Bkpt;
  switch (op) {
  case kOpCmp: opcode = kX86Cmp32RT;  break;
  default:
    LOG(FATAL) << "Bad opcode: " << op;
    break;
  }
  newLIR2(cUnit, opcode, rDest, threadOffset);
}

void genEntrySequence(CompilationUnit* cUnit, RegLocation* argLocs,
                      RegLocation rlMethod)
{
  /*
   * On entry, rARG0, rARG1, rARG2 are live.  Let the register
   * allocation mechanism know so it doesn't try to use any of them when
   * expanding the frame or flushing.  This leaves the utility
   * code with no spare temps.
   */
  oatLockTemp(cUnit, rARG0);
  oatLockTemp(cUnit, rARG1);
  oatLockTemp(cUnit, rARG2);

  /* Build frame, return address already on stack */
  opRegImm(cUnit, kOpSub, rSP, cUnit->frameSize - 4);

  /*
   * We can safely skip the stack overflow check if we're
   * a leaf *and* our frame size < fudge factor.
   */
  bool skipOverflowCheck = ((cUnit->attrs & METHOD_IS_LEAF) &&
                ((size_t)cUnit->frameSize <
                Thread::kStackOverflowReservedBytes));
  newLIR0(cUnit, kPseudoMethodEntry);
  /* Spill core callee saves */
  spillCoreRegs(cUnit);
  /* NOTE: promotion of FP regs currently unsupported, thus no FP spill */
  DCHECK_EQ(cUnit->numFPSpills, 0);
  if (!skipOverflowCheck) {
    // cmp rSP, fs:[stack_end_]; jcc throw_launchpad
    LIR* tgt = rawLIR(cUnit, 0, kPseudoThrowTarget, kThrowStackOverflow, 0, 0, 0, 0);
    opRegThreadMem(cUnit, kOpCmp, rSP, Thread::StackEndOffset().Int32Value());
    opCondBranch(cUnit, kCondUlt, tgt);
    // Remember branch target - will process later
    oatInsertGrowableList(cUnit, &cUnit->throwLaunchpads, (intptr_t)tgt);
  }

  flushIns(cUnit, argLocs, rlMethod);

  oatFreeTemp(cUnit, rARG0);
  oatFreeTemp(cUnit, rARG1);
  oatFreeTemp(cUnit, rARG2);
}

void genExitSequence(CompilationUnit* cUnit) {
  /*
   * In the exit path, rRET0/rRET1 are live - make sure they aren't
   * allocated by the register utilities as temps.
   */
  oatLockTemp(cUnit, rRET0);
  oatLockTemp(cUnit, rRET1);

  newLIR0(cUnit, kPseudoMethodExit);
  unSpillCoreRegs(cUnit);
  /* Remove frame except for return address */
  opRegImm(cUnit, kOpAdd, rSP, cUnit->frameSize - 4);
  newLIR0(cUnit, kX86Ret);
}

/*
 * Nop any unconditional branches that go to the next instruction.
 * Note: new redundant branches may be inserted later, and we'll
 * use a check in final instruction assembly to nop those out.
 */
void removeRedundantBranches(CompilationUnit* cUnit) {
  LIR* thisLIR;

  for (thisLIR = (LIR*) cUnit->firstLIRInsn;
    thisLIR != (LIR*) cUnit->lastLIRInsn;
    thisLIR = NEXT_LIR(thisLIR)) {

  /* Branch to the next instruction */
  if (thisLIR->opcode == kX86Jmp8 || thisLIR->opcode == kX86Jmp32) {
    LIR* nextLIR = thisLIR;

    while (true) {
      nextLIR = NEXT_LIR(nextLIR);

      /*
       * Is the branch target the next instruction?
       */
      if (nextLIR == (LIR*) thisLIR->target) {
        thisLIR->flags.isNop = true;
        break;
      }

      /*
       * Found real useful stuff between the branch and the target.
       * Need to explicitly check the lastLIRInsn here because it
       * might be the last real instruction.
       */
      if (!isPseudoOpcode(nextLIR->opcode) ||
          (nextLIR = (LIR*) cUnit->lastLIRInsn))
        break;
      }
    }
  }
}


/* Common initialization routine for an architecture family */
bool oatArchInit() {
  int i;

  for (i = 0; i < kX86Last; i++) {
    if (EncodingMap[i].opcode != i) {
      LOG(FATAL) << "Encoding order for " << EncodingMap[i].name
                 << " is wrong: expecting " << i << ", seeing "
                 << (int)EncodingMap[i].opcode;
    }
  }

  return oatArchVariantInit();
}

// Not used in x86
int loadHelper(CompilationUnit* cUnit, int offset)
{
  LOG(FATAL) << "Unexpected use of loadHelper in x86";
  return INVALID_REG;
}


}  // namespace art