src/compiler/codegen/arm/Thumb2/Gen.cc

/*
 * 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 codegen for the Thumb2 ISA and is intended to be
 * includes by:
 *
 *        Codegen-$(TARGET_ARCH_VARIANT).c
 *
 */

#include "oat_compilation_unit.h"
#include "oat/runtime/oat_support_entrypoints.h"

namespace art {


/* Return the position of an ssa name within the argument list */
int inPosition(CompilationUnit* cUnit, int sReg)
{
  int vReg = SRegToVReg(cUnit, sReg);
  return vReg - cUnit->numRegs;
}

/*
 * Describe an argument.  If it's already in an arg register, just leave it
 * there.  NOTE: all live arg registers must be locked prior to this call
 * to avoid having them allocated as a temp by downstream utilities.
 */
RegLocation argLoc(CompilationUnit* cUnit, RegLocation loc)
{
  int argNum = inPosition(cUnit, loc.sRegLow);
  if (loc.wide) {
    if (argNum == 2) {
      // Bad case - half in register, half in frame.  Just punt
      loc.location = kLocInvalid;
    } else if (argNum < 2) {
      loc.lowReg = rARG1 + argNum;
      loc.highReg = loc.lowReg + 1;
      loc.location = kLocPhysReg;
    } else {
      loc.location = kLocDalvikFrame;
    }
  } else {
    if (argNum < 3) {
      loc.lowReg = rARG1 + argNum;
      loc.location = kLocPhysReg;
    } else {
      loc.location = kLocDalvikFrame;
    }
  }
  return loc;
}

/*
 * Load an argument.  If already in a register, just return.  If in
 * the frame, we can't use the normal loadValue() because it assumed
 * a proper frame - and we're frameless.
 */
RegLocation loadArg(CompilationUnit* cUnit, RegLocation loc)
{
  if (loc.location == kLocDalvikFrame) {
    int start = (inPosition(cUnit, loc.sRegLow) + 1) * sizeof(uint32_t);
    loc.lowReg = oatAllocTemp(cUnit);
    loadWordDisp(cUnit, rSP, start, loc.lowReg);
    if (loc.wide) {
      loc.highReg = oatAllocTemp(cUnit);
      loadWordDisp(cUnit, rSP, start + sizeof(uint32_t), loc.highReg);
    }
    loc.location = kLocPhysReg;
  }
  return loc;
}

/* Lock any referenced arguments that arrive in registers */
void lockLiveArgs(CompilationUnit* cUnit, MIR* mir)
{
  int firstIn = cUnit->numRegs;
  const int numArgRegs = 3;  // TODO: generalize & move to RegUtil.cc
  for (int i = 0; i < mir->ssaRep->numUses; i++) {
    int vReg = SRegToVReg(cUnit, mir->ssaRep->uses[i]);
    int inPosition = vReg - firstIn;
    if (inPosition < numArgRegs) {
      oatLockTemp(cUnit, rARG1 + inPosition);
    }
  }
}

/* Find the next MIR, which may be in a following basic block */
MIR* getNextMir(CompilationUnit* cUnit, BasicBlock** pBb, MIR* mir)
{
  BasicBlock* bb = *pBb;
  MIR* origMir = mir;
  while (bb != NULL) {
    if (mir != NULL) {
      mir = mir->next;
    }
    if (mir != NULL) {
      return mir;
    } else {
      bb = bb->fallThrough;
      *pBb = bb;
      if (bb) {
         mir = bb->firstMIRInsn;
         if (mir != NULL) {
           return mir;
         }
      }
    }
  }
  return origMir;
}

/* Used for the "printMe" listing */
void genPrintLabel(CompilationUnit *cUnit, MIR* mir)
{
  LIR* boundaryLIR;
  /* Mark the beginning of a Dalvik instruction for line tracking */
  char* instStr = cUnit->printMe ?
     oatGetDalvikDisassembly(cUnit, mir->dalvikInsn, "") : NULL;
  boundaryLIR = newLIR1(cUnit, kPseudoDalvikByteCodeBoundary,
     (intptr_t) instStr);
  cUnit->boundaryMap.Put(mir->offset, boundaryLIR);
  /* Don't generate the SSA annotation unless verbose mode is on */
  if (cUnit->printMe && mir->ssaRep) {
    char* ssaString = oatGetSSAString(cUnit, mir->ssaRep);
    newLIR1(cUnit, kPseudoSSARep, (int) ssaString);
  }
}

MIR* specialIGet(CompilationUnit* cUnit, BasicBlock** bb, MIR* mir,
                 OpSize size, bool longOrDouble, bool isObject)
{
  int fieldOffset;
  bool isVolatile;
  uint32_t fieldIdx = mir->dalvikInsn.vC;
  bool fastPath = fastInstance(cUnit, fieldIdx, fieldOffset, isVolatile, false);
  if (!fastPath || !(mir->optimizationFlags & MIR_IGNORE_NULL_CHECK)) {
    return NULL;
  }
  RegLocation rlObj = oatGetSrc(cUnit, mir, 0);
  lockLiveArgs(cUnit, mir);
  rlObj = argLoc(cUnit, rlObj);
  RegLocation rlDest;
  if (longOrDouble) {
    rlDest = oatGetReturnWide(cUnit, false);
  } else {
    rlDest = oatGetReturn(cUnit, false);
  }
  // Point of no return - no aborts after this
  genPrintLabel(cUnit, mir);
  rlObj = loadArg(cUnit, rlObj);
  genIGet(cUnit, mir, size, rlDest, rlObj, longOrDouble, isObject);
  return getNextMir(cUnit, bb, mir);
}

MIR* specialIPut(CompilationUnit* cUnit, BasicBlock** bb, MIR* mir,
                 OpSize size, bool longOrDouble, bool isObject)
{
  int fieldOffset;
  bool isVolatile;
  uint32_t fieldIdx = mir->dalvikInsn.vC;
  bool fastPath = fastInstance(cUnit, fieldIdx, fieldOffset, isVolatile, false);
  if (!fastPath || !(mir->optimizationFlags & MIR_IGNORE_NULL_CHECK)) {
    return NULL;
  }
  RegLocation rlSrc;
  RegLocation rlObj;
  lockLiveArgs(cUnit, mir);
  if (longOrDouble) {
    rlSrc = oatGetSrcWide(cUnit, mir, 0, 1);
    rlObj = oatGetSrc(cUnit, mir, 2);
  } else {
    rlSrc = oatGetSrc(cUnit, mir, 0);
    rlObj = oatGetSrc(cUnit, mir, 1);
  }
  rlSrc = argLoc(cUnit, rlSrc);
  rlObj = argLoc(cUnit, rlObj);
  // Reject if source is split across registers & frame
  if (rlObj.location == kLocInvalid) {
    oatResetRegPool(cUnit);
    return NULL;
  }
  // Point of no return - no aborts after this
  genPrintLabel(cUnit, mir);
  rlObj = loadArg(cUnit, rlObj);
  rlSrc = loadArg(cUnit, rlSrc);
  genIPut(cUnit, mir, size, rlSrc, rlObj, longOrDouble, isObject);
  return getNextMir(cUnit, bb, mir);
}

MIR* specialIdentity(CompilationUnit* cUnit, MIR* mir)
{
  RegLocation rlSrc;
  RegLocation rlDest;
  bool wide = (mir->ssaRep->numUses == 2);
  if (wide) {
    rlSrc = oatGetSrcWide(cUnit, mir, 0, 1);
    rlDest = oatGetReturnWide(cUnit, false);
  } else {
    rlSrc = oatGetSrc(cUnit, mir, 0);
    rlDest = oatGetReturn(cUnit, false);
  }
  lockLiveArgs(cUnit, mir);
  rlSrc = argLoc(cUnit, rlSrc);
  if (rlSrc.location == kLocInvalid) {
    oatResetRegPool(cUnit);
    return NULL;
  }
  // Point of no return - no aborts after this
  genPrintLabel(cUnit, mir);
  rlSrc = loadArg(cUnit, rlSrc);
  if (wide) {
    storeValueWide(cUnit, rlDest, rlSrc);
  } else {
    storeValue(cUnit, rlDest, rlSrc);
  }
  return mir;
}

/*
 * Special-case code genration for simple non-throwing leaf methods.
 */
void genSpecialCase(CompilationUnit* cUnit, BasicBlock* bb, MIR* mir,
          SpecialCaseHandler specialCase)
{
   cUnit->currentDalvikOffset = mir->offset;
   MIR* nextMir = NULL;
   switch (specialCase) {
     case kNullMethod:
       DCHECK(mir->dalvikInsn.opcode == Instruction::RETURN_VOID);
       nextMir = mir;
       break;
     case kConstFunction:
       genPrintLabel(cUnit, mir);
       loadConstant(cUnit, rRET0, mir->dalvikInsn.vB);
       nextMir = getNextMir(cUnit, &bb, mir);
       break;
     case kIGet:
       nextMir = specialIGet(cUnit, &bb, mir, kWord, false, false);
       break;
     case kIGetBoolean:
     case kIGetByte:
       nextMir = specialIGet(cUnit, &bb, mir, kUnsignedByte, false, false);
       break;
     case kIGetObject:
       nextMir = specialIGet(cUnit, &bb, mir, kWord, false, true);
       break;
     case kIGetChar:
       nextMir = specialIGet(cUnit, &bb, mir, kUnsignedHalf, false, false);
       break;
     case kIGetShort:
       nextMir = specialIGet(cUnit, &bb, mir, kSignedHalf, false, false);
       break;
     case kIGetWide:
       nextMir = specialIGet(cUnit, &bb, mir, kLong, true, false);
       break;
     case kIPut:
       nextMir = specialIPut(cUnit, &bb, mir, kWord, false, false);
       break;
     case kIPutBoolean:
     case kIPutByte:
       nextMir = specialIPut(cUnit, &bb, mir, kUnsignedByte, false, false);
       break;
     case kIPutObject:
       nextMir = specialIPut(cUnit, &bb, mir, kWord, false, true);
       break;
     case kIPutChar:
       nextMir = specialIPut(cUnit, &bb, mir, kUnsignedHalf, false, false);
       break;
     case kIPutShort:
       nextMir = specialIPut(cUnit, &bb, mir, kSignedHalf, false, false);
       break;
     case kIPutWide:
       nextMir = specialIPut(cUnit, &bb, mir, kLong, true, false);
       break;
     case kIdentity:
       nextMir = specialIdentity(cUnit, mir);
       break;
     default:
       return;
   }
   if (nextMir != NULL) {
    cUnit->currentDalvikOffset = nextMir->offset;
    if (specialCase != kIdentity) {
      genPrintLabel(cUnit, nextMir);
    }
    newLIR1(cUnit, kThumbBx, rLR);
    cUnit->coreSpillMask = 0;
    cUnit->numCoreSpills = 0;
    cUnit->fpSpillMask = 0;
    cUnit->numFPSpills = 0;
    cUnit->frameSize = 0;
    cUnit->coreVmapTable.clear();
    cUnit->fpVmapTable.clear();
  }
}

/*
 * Generate a Thumb2 IT instruction, which can nullify up to
 * four subsequent instructions based on a condition and its
 * inverse.  The condition applies to the first instruction, which
 * is executed if the condition is met.  The string "guide" consists
 * of 0 to 3 chars, and applies to the 2nd through 4th instruction.
 * A "T" means the instruction is executed if the condition is
 * met, and an "E" means the instruction is executed if the condition
 * is not met.
 */
LIR* opIT(CompilationUnit* cUnit, ArmConditionCode code, const char* guide)
{
  int mask;
  int condBit = code & 1;
  int altBit = condBit ^ 1;
  int mask3 = 0;
  int mask2 = 0;
  int mask1 = 0;

  //Note: case fallthroughs intentional
  switch (strlen(guide)) {
    case 3:
      mask1 = (guide[2] == 'T') ? condBit : altBit;
    case 2:
      mask2 = (guide[1] == 'T') ? condBit : altBit;
    case 1:
      mask3 = (guide[0] == 'T') ? condBit : altBit;
      break;
    case 0:
      break;
    default:
      LOG(FATAL) << "OAT: bad case in opIT";
  }
  mask = (mask3 << 3) | (mask2 << 2) | (mask1 << 1) |
       (1 << (3 - strlen(guide)));
  return newLIR2(cUnit, kThumb2It, code, mask);
}

/*
 * The sparse table in the literal pool is an array of <key,displacement>
 * pairs.  For each set, we'll load them as a pair using ldmia.
 * This means that the register number of the temp we use for the key
 * must be lower than the reg for the displacement.
 *
 * The test loop will look something like:
 *
 *   adr   rBase, <table>
 *   ldr   rVal, [rSP, vRegOff]
 *   mov   rIdx, #tableSize
 * lp:
 *   ldmia rBase!, {rKey, rDisp}
 *   sub   rIdx, #1
 *   cmp   rVal, rKey
 *   ifeq
 *   add   rPC, rDisp   ; This is the branch from which we compute displacement
 *   cbnz  rIdx, lp
 */
void genSparseSwitch(CompilationUnit* cUnit, MIR* mir, RegLocation rlSrc,
                     LIR* labelList)
{
  const u2* table = cUnit->insns + mir->offset + mir->dalvikInsn.vB;
  if (cUnit->printMe) {
    dumpSparseSwitchTable(table);
  }
  // Add the table to the list - we'll process it later
  SwitchTable *tabRec = (SwitchTable *)oatNew(cUnit, sizeof(SwitchTable),
                                              true, kAllocData);
  tabRec->table = table;
  tabRec->vaddr = mir->offset;
  int size = table[1];
  tabRec->targets = (LIR* *)oatNew(cUnit, size * sizeof(LIR*), true, kAllocLIR);
  oatInsertGrowableList(cUnit, &cUnit->switchTables, (intptr_t)tabRec);

  // Get the switch value
  rlSrc = loadValue(cUnit, rlSrc, kCoreReg);
  int rBase = oatAllocTemp(cUnit);
  /* Allocate key and disp temps */
  int rKey = oatAllocTemp(cUnit);
  int rDisp = oatAllocTemp(cUnit);
  // Make sure rKey's register number is less than rDisp's number for ldmia
  if (rKey > rDisp) {
    int tmp = rDisp;
    rDisp = rKey;
    rKey = tmp;
  }
  // Materialize a pointer to the switch table
  newLIR3(cUnit, kThumb2Adr, rBase, 0, (intptr_t)tabRec);
  // Set up rIdx
  int rIdx = oatAllocTemp(cUnit);
  loadConstant(cUnit, rIdx, size);
  // Establish loop branch target
  LIR* target = newLIR0(cUnit, kPseudoTargetLabel);
  // Load next key/disp
  newLIR2(cUnit, kThumb2LdmiaWB, rBase, (1 << rKey) | (1 << rDisp));
  opRegReg(cUnit, kOpCmp, rKey, rlSrc.lowReg);
  // Go if match. NOTE: No instruction set switch here - must stay Thumb2
  opIT(cUnit, kArmCondEq, "");
  LIR* switchBranch = newLIR1(cUnit, kThumb2AddPCR, rDisp);
  tabRec->anchor = switchBranch;
  // Needs to use setflags encoding here
  newLIR3(cUnit, kThumb2SubsRRI12, rIdx, rIdx, 1);
  opCondBranch(cUnit, kCondNe, target);
}


void genPackedSwitch(CompilationUnit* cUnit, MIR* mir, RegLocation rlSrc)
{
  const u2* table = cUnit->insns + mir->offset + mir->dalvikInsn.vB;
  if (cUnit->printMe) {
    dumpPackedSwitchTable(table);
  }
  // Add the table to the list - we'll process it later
  SwitchTable *tabRec = (SwitchTable *)oatNew(cUnit, sizeof(SwitchTable),
                                              true, kAllocData);
  tabRec->table = table;
  tabRec->vaddr = mir->offset;
  int size = table[1];
  tabRec->targets = (LIR* *)oatNew(cUnit, size * sizeof(LIR*), true, kAllocLIR);
  oatInsertGrowableList(cUnit, &cUnit->switchTables, (intptr_t)tabRec);

  // Get the switch value
  rlSrc = loadValue(cUnit, rlSrc, kCoreReg);
  int tableBase = oatAllocTemp(cUnit);
  // Materialize a pointer to the switch table
  newLIR3(cUnit, kThumb2Adr, tableBase, 0, (intptr_t)tabRec);
  int lowKey = s4FromSwitchData(&table[2]);
  int keyReg;
  // Remove the bias, if necessary
  if (lowKey == 0) {
    keyReg = rlSrc.lowReg;
  } else {
    keyReg = oatAllocTemp(cUnit);
    opRegRegImm(cUnit, kOpSub, keyReg, rlSrc.lowReg, lowKey);
  }
  // Bounds check - if < 0 or >= size continue following switch
  opRegImm(cUnit, kOpCmp, keyReg, size-1);
  LIR* branchOver = opCondBranch(cUnit, kCondHi, NULL);

  // Load the displacement from the switch table
  int dispReg = oatAllocTemp(cUnit);
  loadBaseIndexed(cUnit, tableBase, keyReg, dispReg, 2, kWord);

  // ..and go! NOTE: No instruction set switch here - must stay Thumb2
  LIR* switchBranch = newLIR1(cUnit, kThumb2AddPCR, dispReg);
  tabRec->anchor = switchBranch;

  /* branchOver target here */
  LIR* target = newLIR0(cUnit, kPseudoTargetLabel);
  branchOver->target = (LIR*)target;
}

/*
 * Array data table format:
 *  ushort ident = 0x0300   magic value
 *  ushort width            width of each element in the table
 *  uint   size             number of elements in the table
 *  ubyte  data[size*width] table of data values (may contain a single-byte
 *                          padding at the end)
 *
 * Total size is 4+(width * size + 1)/2 16-bit code units.
 */
void genFillArrayData(CompilationUnit* cUnit, MIR* mir, RegLocation rlSrc)
{
  const u2* table = cUnit->insns + mir->offset + mir->dalvikInsn.vB;
  // Add the table to the list - we'll process it later
  FillArrayData *tabRec = (FillArrayData *)
     oatNew(cUnit, sizeof(FillArrayData), true, kAllocData);
  tabRec->table = table;
  tabRec->vaddr = mir->offset;
  u2 width = tabRec->table[1];
  u4 size = tabRec->table[2] | (((u4)tabRec->table[3]) << 16);
  tabRec->size = (size * width) + 8;

  oatInsertGrowableList(cUnit, &cUnit->fillArrayData, (intptr_t)tabRec);

  // Making a call - use explicit registers
  oatFlushAllRegs(cUnit);   /* Everything to home location */
  loadValueDirectFixed(cUnit, rlSrc, r0);
  loadWordDisp(cUnit, rSELF, ENTRYPOINT_OFFSET(pHandleFillArrayDataFromCode),
               rLR);
  // Materialize a pointer to the fill data image
  newLIR3(cUnit, kThumb2Adr, r1, 0, (intptr_t)tabRec);
  oatClobberCalleeSave(cUnit);
  opReg(cUnit, kOpBlx, rLR);
}

void genNegFloat(CompilationUnit* cUnit, RegLocation rlDest, RegLocation rlSrc)
{
  RegLocation rlResult;
  rlSrc = loadValue(cUnit, rlSrc, kFPReg);
  rlResult = oatEvalLoc(cUnit, rlDest, kFPReg, true);
  newLIR2(cUnit, kThumb2Vnegs, rlResult.lowReg, rlSrc.lowReg);
  storeValue(cUnit, rlDest, rlResult);
}

void genNegDouble(CompilationUnit* cUnit, RegLocation rlDest, RegLocation rlSrc)
{
  RegLocation rlResult;
  rlSrc = loadValueWide(cUnit, rlSrc, kFPReg);
  rlResult = oatEvalLoc(cUnit, rlDest, kFPReg, true);
  newLIR2(cUnit, kThumb2Vnegd, S2D(rlResult.lowReg, rlResult.highReg),
          S2D(rlSrc.lowReg, rlSrc.highReg));
  storeValueWide(cUnit, rlDest, rlResult);
}

/*
 * Handle simple case (thin lock) inline.  If it's complicated, bail
 * out to the heavyweight lock/unlock routines.  We'll use dedicated
 * registers here in order to be in the right position in case we
 * to bail to dvm[Lock/Unlock]Object(self, object)
 *
 * r0 -> self pointer [arg0 for dvm[Lock/Unlock]Object
 * r1 -> object [arg1 for dvm[Lock/Unlock]Object
 * r2 -> intial contents of object->lock, later result of strex
 * r3 -> self->threadId
 * r12 -> allow to be used by utilities as general temp
 *
 * The result of the strex is 0 if we acquire the lock.
 *
 * See comments in Sync.c for the layout of the lock word.
 * Of particular interest to this code is the test for the
 * simple case - which we handle inline.  For monitor enter, the
 * simple case is thin lock, held by no-one.  For monitor exit,
 * the simple case is thin lock, held by the unlocking thread with
 * a recurse count of 0.
 *
 * A minor complication is that there is a field in the lock word
 * unrelated to locking: the hash state.  This field must be ignored, but
 * preserved.
 *
 */
void genMonitorEnter(CompilationUnit* cUnit, MIR* mir, RegLocation rlSrc)
{
  oatFlushAllRegs(cUnit);
  DCHECK_EQ(LW_SHAPE_THIN, 0);
  loadValueDirectFixed(cUnit, rlSrc, r0);  // Get obj
  oatLockCallTemps(cUnit);  // Prepare for explicit register usage
  genNullCheck(cUnit, rlSrc.sRegLow, r0, mir);
  loadWordDisp(cUnit, rSELF, Thread::ThinLockIdOffset().Int32Value(), r2);
  newLIR3(cUnit, kThumb2Ldrex, r1, r0,
          Object::MonitorOffset().Int32Value() >> 2); // Get object->lock
  // Align owner
  opRegImm(cUnit, kOpLsl, r2, LW_LOCK_OWNER_SHIFT);
  // Is lock unheld on lock or held by us (==threadId) on unlock?
  newLIR4(cUnit, kThumb2Bfi, r2, r1, 0, LW_LOCK_OWNER_SHIFT - 1);
  newLIR3(cUnit, kThumb2Bfc, r1, LW_HASH_STATE_SHIFT, LW_LOCK_OWNER_SHIFT - 1);
  opRegImm(cUnit, kOpCmp, r1, 0);
  opIT(cUnit, kArmCondEq, "");
  newLIR4(cUnit, kThumb2Strex, r1, r2, r0,
          Object::MonitorOffset().Int32Value() >> 2);
  opRegImm(cUnit, kOpCmp, r1, 0);
  opIT(cUnit, kArmCondNe, "T");
  // Go expensive route - artLockObjectFromCode(self, obj);
  loadWordDisp(cUnit, rSELF, ENTRYPOINT_OFFSET(pLockObjectFromCode), rLR);
  oatClobberCalleeSave(cUnit);
  opReg(cUnit, kOpBlx, rLR);
  oatGenMemBarrier(cUnit, kSY);
}

/*
 * For monitor unlock, we don't have to use ldrex/strex.  Once
 * we've determined that the lock is thin and that we own it with
 * a zero recursion count, it's safe to punch it back to the
 * initial, unlock thin state with a store word.
 */
void genMonitorExit(CompilationUnit* cUnit, MIR* mir, RegLocation rlSrc)
{
  DCHECK_EQ(LW_SHAPE_THIN, 0);
  oatFlushAllRegs(cUnit);
  loadValueDirectFixed(cUnit, rlSrc, r0);  // Get obj
  oatLockCallTemps(cUnit);  // Prepare for explicit register usage
  genNullCheck(cUnit, rlSrc.sRegLow, r0, mir);
  loadWordDisp(cUnit, r0, Object::MonitorOffset().Int32Value(), r1); // Get lock
  loadWordDisp(cUnit, rSELF, Thread::ThinLockIdOffset().Int32Value(), r2);
  // Is lock unheld on lock or held by us (==threadId) on unlock?
  opRegRegImm(cUnit, kOpAnd, r3, r1,
              (LW_HASH_STATE_MASK << LW_HASH_STATE_SHIFT));
  // Align owner
  opRegImm(cUnit, kOpLsl, r2, LW_LOCK_OWNER_SHIFT);
  newLIR3(cUnit, kThumb2Bfc, r1, LW_HASH_STATE_SHIFT, LW_LOCK_OWNER_SHIFT - 1);
  opRegReg(cUnit, kOpSub, r1, r2);
  opIT(cUnit, kArmCondEq, "EE");
  storeWordDisp(cUnit, r0, Object::MonitorOffset().Int32Value(), r3);
  // Go expensive route - UnlockObjectFromCode(obj);
  loadWordDisp(cUnit, rSELF, ENTRYPOINT_OFFSET(pUnlockObjectFromCode), rLR);
  oatClobberCalleeSave(cUnit);
  opReg(cUnit, kOpBlx, rLR);
  oatGenMemBarrier(cUnit, kSY);
}

/*
 * 64-bit 3way compare function.
 *     mov   rX, #-1
 *     cmp   op1hi, op2hi
 *     blt   done
 *     bgt   flip
 *     sub   rX, op1lo, op2lo (treat as unsigned)
 *     beq   done
 *     ite   hi
 *     mov(hi)   rX, #-1
 *     mov(!hi)  rX, #1
 * flip:
 *     neg   rX
 * done:
 */
void genCmpLong(CompilationUnit* cUnit, MIR* mir, RegLocation rlDest,
        RegLocation rlSrc1, RegLocation rlSrc2)
{
  LIR* target1;
  LIR* target2;
  rlSrc1 = loadValueWide(cUnit, rlSrc1, kCoreReg);
  rlSrc2 = loadValueWide(cUnit, rlSrc2, kCoreReg);
  int tReg = oatAllocTemp(cUnit);
  loadConstant(cUnit, tReg, -1);
  opRegReg(cUnit, kOpCmp, rlSrc1.highReg, rlSrc2.highReg);
  LIR* branch1 = opCondBranch(cUnit, kCondLt, NULL);
  LIR* branch2 = opCondBranch(cUnit, kCondGt, NULL);
  opRegRegReg(cUnit, kOpSub, tReg, rlSrc1.lowReg, rlSrc2.lowReg);
  LIR* branch3 = opCondBranch(cUnit, kCondEq, NULL);

  opIT(cUnit, kArmCondHi, "E");
  newLIR2(cUnit, kThumb2MovImmShift, tReg, modifiedImmediate(-1));
  loadConstant(cUnit, tReg, 1);
  genBarrier(cUnit);

  target2 = newLIR0(cUnit, kPseudoTargetLabel);
  opRegReg(cUnit, kOpNeg, tReg, tReg);

  target1 = newLIR0(cUnit, kPseudoTargetLabel);

  RegLocation rlTemp = LOC_C_RETURN; // Just using as template, will change
  rlTemp.lowReg = tReg;
  storeValue(cUnit, rlDest, rlTemp);
  oatFreeTemp(cUnit, tReg);

  branch1->target = (LIR*)target1;
  branch2->target = (LIR*)target2;
  branch3->target = branch1->target;
}

void genFusedLongCmpBranch(CompilationUnit* cUnit, BasicBlock* bb, MIR* mir)
{
  LIR* labelList = (LIR*)cUnit->blockLabelList;
  LIR* taken = &labelList[bb->taken->id];
  LIR* notTaken = &labelList[bb->fallThrough->id];
  RegLocation rlSrc1 = oatGetSrcWide(cUnit, mir, 0, 1);
  RegLocation rlSrc2 = oatGetSrcWide(cUnit, mir, 2, 3);
  rlSrc1 = loadValueWide(cUnit, rlSrc1, kCoreReg);
  rlSrc2 = loadValueWide(cUnit, rlSrc2, kCoreReg);
  ConditionCode ccode = static_cast<ConditionCode>(mir->dalvikInsn.arg[0]);
  opRegReg(cUnit, kOpCmp, rlSrc1.highReg, rlSrc2.highReg);
  switch(ccode) {
    case kCondEq:
      opCondBranch(cUnit, kCondNe, notTaken);
      break;
    case kCondNe:
      opCondBranch(cUnit, kCondNe, taken);
      break;
    case kCondLt:
      opCondBranch(cUnit, kCondLt, taken);
      opCondBranch(cUnit, kCondGt, notTaken);
      ccode = kCondCc;
      break;
    case kCondLe:
      opCondBranch(cUnit, kCondLt, taken);
      opCondBranch(cUnit, kCondGt, notTaken);
      ccode = kCondLs;
      break;
    case kCondGt:
      opCondBranch(cUnit, kCondGt, taken);
      opCondBranch(cUnit, kCondLt, notTaken);
      ccode = kCondHi;
      break;
    case kCondGe:
      opCondBranch(cUnit, kCondGt, taken);
      opCondBranch(cUnit, kCondLt, notTaken);
      ccode = kCondCs;
      break;
    default:
      LOG(FATAL) << "Unexpected ccode: " << (int)ccode;
  }
  opRegReg(cUnit, kOpCmp, rlSrc1.lowReg, rlSrc2.lowReg);
  opCondBranch(cUnit, ccode, taken);
}

/*
 * Generate a register comparison to an immediate and branch.  Caller
 * is responsible for setting branch target field.
 */
LIR* opCmpImmBranch(CompilationUnit* cUnit, ConditionCode cond, int reg,
          int checkValue, LIR* target)
{
  LIR* branch;
  int modImm;
  ArmConditionCode armCond = oatArmConditionEncoding(cond);
  if ((LOWREG(reg)) && (checkValue == 0) &&
     ((armCond == kArmCondEq) || (armCond == kArmCondNe))) {
    branch = newLIR2(cUnit, (armCond == kArmCondEq) ? kThumb2Cbz : kThumb2Cbnz,
                     reg, 0);
  } else {
    modImm = modifiedImmediate(checkValue);
    if (LOWREG(reg) && ((checkValue & 0xff) == checkValue)) {
      newLIR2(cUnit, kThumbCmpRI8, reg, checkValue);
    } else if (modImm >= 0) {
      newLIR2(cUnit, kThumb2CmpRI8, reg, modImm);
    } else {
      int tReg = oatAllocTemp(cUnit);
      loadConstant(cUnit, tReg, checkValue);
      opRegReg(cUnit, kOpCmp, reg, tReg);
    }
    branch = newLIR2(cUnit, kThumbBCond, 0, armCond);
  }
  branch->target = target;
  return branch;
}
LIR* opRegCopyNoInsert(CompilationUnit* cUnit, int rDest, int rSrc)
{
  LIR* res;
  ArmOpcode opcode;
  if (FPREG(rDest) || FPREG(rSrc))
    return fpRegCopy(cUnit, rDest, rSrc);
  if (LOWREG(rDest) && LOWREG(rSrc))
    opcode = kThumbMovRR;
  else if (!LOWREG(rDest) && !LOWREG(rSrc))
     opcode = kThumbMovRR_H2H;
  else if (LOWREG(rDest))
     opcode = kThumbMovRR_H2L;
  else
     opcode = kThumbMovRR_L2H;
  res = rawLIR(cUnit, cUnit->currentDalvikOffset, opcode, rDest, rSrc);
  if (!(cUnit->disableOpt & (1 << kSafeOptimizations)) && rDest == rSrc) {
    res->flags.isNop = true;
  }
  return res;
}

LIR* opRegCopy(CompilationUnit* cUnit, int rDest, int rSrc)
{
  LIR* res = opRegCopyNoInsert(cUnit, rDest, rSrc);
  oatAppendLIR(cUnit, (LIR*)res);
  return res;
}

void opRegCopyWide(CompilationUnit* cUnit, int destLo, int destHi,
               int srcLo, int srcHi)
{
  bool destFP = FPREG(destLo) && FPREG(destHi);
  bool srcFP = FPREG(srcLo) && FPREG(srcHi);
  DCHECK_EQ(FPREG(srcLo), FPREG(srcHi));
  DCHECK_EQ(FPREG(destLo), FPREG(destHi));
  if (destFP) {
    if (srcFP) {
      opRegCopy(cUnit, S2D(destLo, destHi), S2D(srcLo, srcHi));
    } else {
      newLIR3(cUnit, kThumb2Fmdrr, S2D(destLo, destHi), srcLo, srcHi);
    }
  } else {
    if (srcFP) {
      newLIR3(cUnit, kThumb2Fmrrd, destLo, destHi, S2D(srcLo, srcHi));
    } else {
      // Handle overlap
      if (srcHi == destLo) {
        opRegCopy(cUnit, destHi, srcHi);
        opRegCopy(cUnit, destLo, srcLo);
      } else {
        opRegCopy(cUnit, destLo, srcLo);
        opRegCopy(cUnit, destHi, srcHi);
      }
    }
  }
}

// Table of magic divisors
enum DividePattern {
  DivideNone,
  Divide3,
  Divide5,
  Divide7,
};

struct MagicTable {
  uint32_t magic;
  uint32_t shift;
  DividePattern pattern;
};

static const MagicTable magicTable[] = {
  {0, 0, DivideNone},        // 0
  {0, 0, DivideNone},        // 1
  {0, 0, DivideNone},        // 2
  {0x55555556, 0, Divide3},  // 3
  {0, 0, DivideNone},        // 4
  {0x66666667, 1, Divide5},  // 5
  {0x2AAAAAAB, 0, Divide3},  // 6
  {0x92492493, 2, Divide7},  // 7
  {0, 0, DivideNone},        // 8
  {0x38E38E39, 1, Divide5},  // 9
  {0x66666667, 2, Divide5},  // 10
  {0x2E8BA2E9, 1, Divide5},  // 11
  {0x2AAAAAAB, 1, Divide5},  // 12
  {0x4EC4EC4F, 2, Divide5},  // 13
  {0x92492493, 3, Divide7},  // 14
  {0x88888889, 3, Divide7},  // 15
};

// Integer division by constant via reciprocal multiply (Hacker's Delight, 10-4)
bool smallLiteralDivide(CompilationUnit* cUnit, Instruction::Code dalvikOpcode,
                        RegLocation rlSrc, RegLocation rlDest, int lit)
{
  if ((lit < 0) || (lit >= (int)(sizeof(magicTable)/sizeof(magicTable[0])))) {
    return false;
  }
  DividePattern pattern = magicTable[lit].pattern;
  if (pattern == DivideNone) {
    return false;
  }
  // Tuning: add rem patterns
  if (dalvikOpcode != Instruction::DIV_INT_LIT8) {
    return false;
  }

  int rMagic = oatAllocTemp(cUnit);
  loadConstant(cUnit, rMagic, magicTable[lit].magic);
  rlSrc = loadValue(cUnit, rlSrc, kCoreReg);
  RegLocation rlResult = oatEvalLoc(cUnit, rlDest, kCoreReg, true);
  int rHi = oatAllocTemp(cUnit);
  int rLo = oatAllocTemp(cUnit);
  newLIR4(cUnit, kThumb2Smull, rLo, rHi, rMagic, rlSrc.lowReg);
  switch(pattern) {
    case Divide3:
      opRegRegRegShift(cUnit, kOpSub, rlResult.lowReg, rHi,
               rlSrc.lowReg, encodeShift(kArmAsr, 31));
      break;
    case Divide5:
      opRegRegImm(cUnit, kOpAsr, rLo, rlSrc.lowReg, 31);
      opRegRegRegShift(cUnit, kOpRsub, rlResult.lowReg, rLo, rHi,
               encodeShift(kArmAsr, magicTable[lit].shift));
      break;
    case Divide7:
      opRegReg(cUnit, kOpAdd, rHi, rlSrc.lowReg);
      opRegRegImm(cUnit, kOpAsr, rLo, rlSrc.lowReg, 31);
      opRegRegRegShift(cUnit, kOpRsub, rlResult.lowReg, rLo, rHi,
               encodeShift(kArmAsr, magicTable[lit].shift));
      break;
    default:
      LOG(FATAL) << "Unexpected pattern: " << (int)pattern;
  }
  storeValue(cUnit, rlDest, rlResult);
  return true;
}

}  // namespace art