src/compiler/codegen/x86/X86/Gen.cc

/*
 * Copyright (C) 2012 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 X86 ISA and is intended to be
 * includes by:
 *
 *        Codegen-$(TARGET_ARCH_VARIANT).c
 *
 */

namespace art {

void genSpecialCase(CompilationUnit* cUnit, BasicBlock* bb, MIR* mir,
                    SpecialCaseHandler specialCase)
{
    // TODO
}

/*
 * Perform register memory operation.
 */
LIR* genRegMemCheck(CompilationUnit* cUnit, ConditionCode cCode,
                    int reg1, int base, int offset, MIR* mir, ThrowKind kind)
{
    LIR* tgt = rawLIR(cUnit, 0, kPseudoThrowTarget, kind,
                      mir ? mir->offset : 0, reg1, base, offset);
    opRegMem(cUnit, kOpCmp, reg1, base, offset);
    LIR* branch = opCondBranch(cUnit, cCode, tgt);
    // Remember branch target - will process later
    oatInsertGrowableList(cUnit, &cUnit->throwLaunchpads, (intptr_t)tgt);
    return branch;
}

/*
 * The lack of pc-relative loads on X86 presents somewhat of a challenge
 * for our PIC switch table strategy.  To materialize the current location
 * we'll do a dummy JAL and reference our tables using r_RA as the
 * base register.  Note that r_RA will be used both as the base to
 * locate the switch table data and as the reference base for the switch
 * target offsets stored in the table.  We'll use a special pseudo-instruction
 * to represent the jal and trigger the construction of the
 * switch table offsets (which will happen after final assembly and all
 * labels are fixed).
 *
 * The test loop will look something like:
 *
 *   ori   rEnd, r_ZERO, #tableSize  ; size in bytes
 *   jal   BaseLabel         ; stores "return address" (BaseLabel) in r_RA
 *   nop                     ; opportunistically fill
 * BaseLabel:
 *   addiu rBase, r_RA, <table> - <BaseLabel>  ; table relative to BaseLabel
     addu  rEnd, rEnd, rBase                   ; end of table
 *   lw    rVal, [rSP, vRegOff]                ; Test Value
 * loop:
 *   beq   rBase, rEnd, done
 *   lw    rKey, 0(rBase)
 *   addu  rBase, 8
 *   bne   rVal, rKey, loop
 *   lw    rDisp, -4(rBase)
 *   addu  r_RA, rDisp
 *   jr    r_RA
 * done:
 *
 */
void genSparseSwitch(CompilationUnit* cUnit, MIR* mir, RegLocation rlSrc)
{
    UNIMPLEMENTED(WARNING) << "genSparseSwitch";
    newLIR0(cUnit, kX86Bkpt);
    return;
#if 0
    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 elements = table[1];
    tabRec->targets = (LIR* *)oatNew(cUnit, elements * sizeof(LIR*), true,
                                     kAllocLIR);
    oatInsertGrowableList(cUnit, &cUnit->switchTables, (intptr_t)tabRec);

    // The table is composed of 8-byte key/disp pairs
    int byteSize = elements * 8;

    int sizeHi = byteSize >> 16;
    int sizeLo = byteSize & 0xffff;

    int rEnd = oatAllocTemp(cUnit);
    if (sizeHi) {
        newLIR2(cUnit, kX86Lui, rEnd, sizeHi);
    }
    // Must prevent code motion for the curr pc pair
    genBarrier(cUnit);  // Scheduling barrier
    newLIR0(cUnit, kX86CurrPC);  // Really a jal to .+8
    // Now, fill the branch delay slot
    if (sizeHi) {
        newLIR3(cUnit, kX86Ori, rEnd, rEnd, sizeLo);
    } else {
        newLIR3(cUnit, kX86Ori, rEnd, r_ZERO, sizeLo);
    }
    genBarrier(cUnit);  // Scheduling barrier

    // Construct BaseLabel and set up table base register
    LIR* baseLabel = newLIR0(cUnit, kPseudoTargetLabel);
    // Remember base label so offsets can be computed later
    tabRec->anchor = baseLabel;
    int rBase = oatAllocTemp(cUnit);
    newLIR4(cUnit, kX86Delta, rBase, 0, (intptr_t)baseLabel, (intptr_t)tabRec);
    opRegRegReg(cUnit, kOpAdd, rEnd, rEnd, rBase);

    // Grab switch test value
    rlSrc = loadValue(cUnit, rlSrc, kCoreReg);

    // Test loop
    int rKey = oatAllocTemp(cUnit);
    LIR* loopLabel = newLIR0(cUnit, kPseudoTargetLabel);
    LIR* exitBranch = opCmpBranch(cUnit , kCondEq, rBase, rEnd, NULL);
    loadWordDisp(cUnit, rBase, 0, rKey);
    opRegImm(cUnit, kOpAdd, rBase, 8);
    opCmpBranch(cUnit, kCondNe, rlSrc.lowReg, rKey, loopLabel);
    int rDisp = oatAllocTemp(cUnit);
    loadWordDisp(cUnit, rBase, -4, rDisp);
    opRegRegReg(cUnit, kOpAdd, r_RA, r_RA, rDisp);
    opReg(cUnit, kOpBx, r_RA);

    // Loop exit
    LIR* exitLabel = newLIR0(cUnit, kPseudoTargetLabel);
    exitBranch->target = exitLabel;
#endif
}

/*
 * Code pattern will look something like:
 *
 *   lw    rVal
 *   jal   BaseLabel         ; stores "return address" (BaseLabel) in r_RA
 *   nop                     ; opportunistically fill
 *   [subiu rVal, bias]      ; Remove bias if lowVal != 0
 *   bound check -> done
 *   lw    rDisp, [r_RA, rVal]
 *   addu  r_RA, rDisp
 *   jr    r_RA
 * done:
 */
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 startOfMethodReg = oatAllocTemp(cUnit);
  // Materialize a pointer to the switch table
  //newLIR0(cUnit, kX86Bkpt);
  newLIR1(cUnit, kX86StartOfMethod, startOfMethodReg);
  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);
  newLIR5(cUnit, kX86PcRelLoadRA, dispReg, startOfMethodReg, keyReg, 2, (intptr_t)tabRec);
  // Add displacement to start of method
  opRegReg(cUnit, kOpAdd, startOfMethodReg, dispReg);
  // ..and go!
  LIR* switchBranch = newLIR1(cUnit, kX86JmpR, startOfMethodReg);
  tabRec->anchor = switchBranch;

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

void callRuntimeHelperRegReg(CompilationUnit* cUnit, int helperOffset, int arg0, int arg1);
/*
 * 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, rARG0);
  // Materialize a pointer to the fill data image
  newLIR1(cUnit, kX86StartOfMethod, rARG2);
  newLIR2(cUnit, kX86PcRelAdr, rARG1, (intptr_t)tabRec);
  newLIR2(cUnit, kX86Add32RR, rARG1, rARG2);
  callRuntimeHelperRegReg(cUnit, ENTRYPOINT_OFFSET(pHandleFillArrayDataFromCode), rARG0, rARG1);
}

void genNegFloat(CompilationUnit *cUnit, RegLocation rlDest, RegLocation rlSrc)
{
    UNIMPLEMENTED(WARNING) << "genNegFloat";
    newLIR0(cUnit, kX86Bkpt);
#if 0
    RegLocation rlResult;
    rlSrc = loadValue(cUnit, rlSrc, kCoreReg);
    rlResult = oatEvalLoc(cUnit, rlDest, kCoreReg, true);
    opRegRegImm(cUnit, kOpAdd, rlResult.lowReg,
                rlSrc.lowReg, 0x80000000);
    storeValue(cUnit, rlDest, rlResult);
#endif
}

void genNegDouble(CompilationUnit *cUnit, RegLocation rlDest, RegLocation rlSrc)
{
    UNIMPLEMENTED(WARNING) << "genNegDouble";
    newLIR0(cUnit, kX86Bkpt);
#if 0
    RegLocation rlResult;
    rlSrc = loadValueWide(cUnit, rlSrc, kCoreReg);
    rlResult = oatEvalLoc(cUnit, rlDest, kCoreReg, true);
    opRegRegImm(cUnit, kOpAdd, rlResult.highReg, rlSrc.highReg,
                        0x80000000);
    opRegCopy(cUnit, rlResult.lowReg, rlSrc.lowReg);
    storeValueWide(cUnit, rlDest, rlResult);
#endif
}

LIR* genNullCheck(CompilationUnit* cUnit, int sReg, int mReg, MIR* mir);
void callRuntimeHelperReg(CompilationUnit* cUnit, int helperOffset, int arg0);

/*
 * TODO: implement fast path to short-circuit thin-lock case
 */
void genMonitorEnter(CompilationUnit* cUnit, MIR* mir, RegLocation rlSrc)
{
    oatFlushAllRegs(cUnit);
    loadValueDirectFixed(cUnit, rlSrc, rARG0);  // Get obj
    oatLockCallTemps(cUnit);  // Prepare for explicit register usage
    genNullCheck(cUnit, rlSrc.sRegLow, rARG0, mir);
    // Go expensive route - artLockObjectFromCode(self, obj);
    callRuntimeHelperReg(cUnit, ENTRYPOINT_OFFSET(pLockObjectFromCode), rARG0);
}

/*
 * TODO: implement fast path to short-circuit thin-lock case
 */
void genMonitorExit(CompilationUnit* cUnit, MIR* mir, RegLocation rlSrc)
{
    oatFlushAllRegs(cUnit);
    loadValueDirectFixed(cUnit, rlSrc, rARG0);  // Get obj
    oatLockCallTemps(cUnit);  // Prepare for explicit register usage
    genNullCheck(cUnit, rlSrc.sRegLow, rARG0, mir);
    // Go expensive route - UnlockObjectFromCode(obj);
    callRuntimeHelperReg(cUnit, ENTRYPOINT_OFFSET(pUnlockObjectFromCode), rARG0);
}

/*
 * Compare two 64-bit values
 *    x = y     return  0
 *    x < y     return -1
 *    x > y     return  1
 *
 *    slt   t0,  x.hi, y.hi;        # (x.hi < y.hi) ? 1:0
 *    sgt   t1,  x.hi, y.hi;        # (y.hi > x.hi) ? 1:0
 *    subu  res, t0, t1             # res = -1:1:0 for [ < > = ]
 *    bnez  res, finish
 *    sltu  t0, x.lo, y.lo
 *    sgtu  r1, x.lo, y.lo
 *    subu  res, t0, t1
 * finish:
 *
 */
void genCmpLong(CompilationUnit* cUnit, MIR* mir, RegLocation rlDest,
                RegLocation rlSrc1, RegLocation rlSrc2)
{
    oatFlushAllRegs(cUnit);
    oatLockCallTemps(cUnit);  // Prepare for explicit register usage
    loadValueDirectWideFixed(cUnit, rlSrc1, r0, r1);
    loadValueDirectWideFixed(cUnit, rlSrc1, 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
    opRegReg(cUnit, kOpOr, r0, r1);   // r0 = high | low - sets ZF
    newLIR2(cUnit, kX86Set8R, r0, kX86CondNz);  // r0 = (r1:r0) != (r2:r3) ? 1 : 0
    newLIR2(cUnit, kX86Movzx8RR, r0, r0);
    opRegImm(cUnit, kOpAsr, r1, 31);  // r1 = high >> 31
    opRegReg(cUnit, kOpOr, r0, r1);   // r0 holds result
    RegLocation rlResult = LOC_C_RETURN;
    storeValue(cUnit, rlDest, rlResult);
}

X86ConditionCode oatX86ConditionEncoding(ConditionCode cond) {
  switch (cond) {
    case kCondEq: return kX86CondEq;
    case kCondNe: return kX86CondNe;
    case kCondCs: return kX86CondC;
    case kCondCc: return kX86CondNc;
    case kCondMi: return kX86CondS;
    case kCondPl: return kX86CondNs;
    case kCondVs: return kX86CondO;
    case kCondVc: return kX86CondNo;
    case kCondHi: return kX86CondA;
    case kCondLs: return kX86CondBe;
    case kCondGe: return kX86CondGe;
    case kCondLt: return kX86CondL;
    case kCondGt: return kX86CondG;
    case kCondLe: return kX86CondLe;
    case kCondAl:
    case kCondNv: LOG(FATAL) << "Should not reach here";
  }
  return kX86CondO;
}

LIR* opCmpBranch(CompilationUnit* cUnit, ConditionCode cond, int src1, int src2, LIR* target)
{
  newLIR2(cUnit, kX86Cmp32RR, src1, src2);
  X86ConditionCode cc = oatX86ConditionEncoding(cond);
  LIR* branch = newLIR2(cUnit, kX86Jcc8, 0 /* lir operand for Jcc offset */ , cc);
  branch->target = target;
  return branch;
}

LIR* opCmpImmBranch(CompilationUnit* cUnit, ConditionCode cond, int reg,
                    int checkValue, LIR* target)
{
  if (false && (checkValue == 0) && (cond == kCondEq || cond == kCondNe)) {
    // TODO: when checkValue == 0 and reg is rCX, use the jcxz/nz opcode
    // newLIR2(cUnit, kX86Test32RR, reg, reg);
  } else {
    newLIR2(cUnit, kX86Cmp32RI, reg, checkValue);
  }
  X86ConditionCode cc = oatX86ConditionEncoding(cond);
  LIR* branch = newLIR2(cUnit, kX86Jcc8, 0 /* lir operand for Jcc offset */ , cc);
  branch->target = target;
  return branch;
}

LIR* opRegCopyNoInsert(CompilationUnit *cUnit, int rDest, int rSrc)
{
    if (FPREG(rDest) || FPREG(rSrc))
        return fpRegCopy(cUnit, rDest, rSrc);
    LIR* res = rawLIR(cUnit, cUnit->currentDalvikOffset, kX86Mov32RR,
                      rDest, rSrc);
    if (rDest == rSrc) {
        res->flags.isNop = true;
    }
    return res;
}

LIR* opRegCopy(CompilationUnit *cUnit, int rDest, int rSrc)
{
    LIR *res = opRegCopyNoInsert(cUnit, rDest, rSrc);
    oatAppendLIR(cUnit, 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);
  assert(FPREG(srcLo) == FPREG(srcHi));
  assert(FPREG(destLo) == FPREG(destHi));
  if (destFP) {
    if (srcFP) {
      opRegCopy(cUnit, S2D(destLo, destHi), S2D(srcLo, srcHi));
    } else {
      UNIMPLEMENTED(WARNING);
      newLIR0(cUnit, kX86Bkpt);
    }
  } else {
    if (srcFP) {
      UNIMPLEMENTED(WARNING);
      newLIR0(cUnit, kX86Bkpt);
    } else {
      // Handle overlap
      if (srcHi == destLo) {
        opRegCopy(cUnit, destHi, srcHi);
        opRegCopy(cUnit, destLo, srcLo);
      } else {
        opRegCopy(cUnit, destLo, srcLo);
        opRegCopy(cUnit, destHi, srcHi);
      }
    }
  }
}

}  // namespace art