CDSPass.cpp

   1 //===-- CDSPass.cpp - xxx -------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 // This file is distributed under the University of Illinois Open Source
   7 // License. See LICENSE.TXT for details.
   8 //
   9 //===----------------------------------------------------------------------===//
  10 //
  11 // This file is a modified version of ThreadSanitizer.cpp, a part of a race detector.
  12 //
  13 // The tool is under development, for the details about previous versions see
  14 // http://code.google.com/p/data-race-test
  15 //
  16 // The instrumentation phase is quite simple:
  17 //   - Insert calls to run-time library before every memory access.
  18 //      - Optimizations may apply to avoid instrumenting some of the accesses.
  19 //   - Insert calls at function entry/exit.
  20 // The rest is handled by the run-time library.
  21 //===----------------------------------------------------------------------===//
  22
  23 #include "llvm/ADT/Statistic.h"
  24 #include "llvm/ADT/StringExtras.h"
  25 #include "llvm/ADT/SmallString.h"
  26 #include "llvm/Analysis/ValueTracking.h"
  27 #include "llvm/Analysis/CaptureTracking.h"
  28 #include "llvm/IR/BasicBlock.h"
  29 #include "llvm/IR/Function.h"
  30 #include "llvm/IR/IRBuilder.h"
  31 #include "llvm/IR/Instructions.h"
  32 #include "llvm/IR/LLVMContext.h"
  33 #include "llvm/IR/LegacyPassManager.h"
  34 #include "llvm/IR/Module.h"
  35 #include "llvm/IR/PassManager.h"
  36 #include "llvm/Pass.h"
  37 #include "llvm/ProfileData/InstrProf.h"
  38 #include "llvm/Support/raw_ostream.h"
  39 #include "llvm/Support/AtomicOrdering.h"
  40 #include "llvm/Support/Debug.h"
  41 #include "llvm/Transforms/Scalar.h"
  42 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
  43 #include "llvm/Transforms/Utils/EscapeEnumerator.h"
  44 // #include "llvm/Transforms/Utils/ModuleUtils.h"
  45 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
  46 #include <vector>
  47
  48 using namespace llvm;
  49
  50 #define DEBUG_TYPE "CDS"
  51 #include <llvm/IR/DebugLoc.h>
  52
  53 Value *getPosition( Instruction * I, IRBuilder <> IRB, bool print = false)
  54 {
  55         const DebugLoc & debug_location = I->getDebugLoc ();
  56         std::string position_string;
  57         {
  58                 llvm::raw_string_ostream position_stream (position_string);
  59                 debug_location . print (position_stream);
  60         }
  61
  62         if (print) {
  63                 errs() << position_string << "\n";
  64         }
  65
  66         return IRB.CreateGlobalStringPtr (position_string);
  67 }
  68
  69 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
  70 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
  71 STATISTIC(NumOmittedReadsBeforeWrite,
  72           "Number of reads ignored due to following writes");
  73 STATISTIC(NumAccessesWithBadSize, "Number of accesses with bad size");
  74 // STATISTIC(NumInstrumentedVtableWrites, "Number of vtable ptr writes");
  75 // STATISTIC(NumInstrumentedVtableReads, "Number of vtable ptr reads");
  76 STATISTIC(NumOmittedReadsFromConstantGlobals,
  77           "Number of reads from constant globals");
  78 STATISTIC(NumOmittedReadsFromVtable, "Number of vtable reads");
  79 STATISTIC(NumOmittedNonCaptured, "Number of accesses ignored due to capturing");
  80
  81 // static const char *const kCDSModuleCtorName = "cds.module_ctor";
  82 // static const char *const kCDSInitName = "cds_init";
  83
  84 Type * OrdTy;
  85 Type * IntPtrTy;
  86 Type * Int8PtrTy;
  87 Type * Int16PtrTy;
  88 Type * Int32PtrTy;
  89 Type * Int64PtrTy;
  90
  91 Type * VoidTy;
  92
  93 static const size_t kNumberOfAccessSizes = 4;
  94
  95 int getAtomicOrderIndex(AtomicOrdering order) {
  96         switch (order) {
  97                 case AtomicOrdering::Monotonic:
  98                         return (int)AtomicOrderingCABI::relaxed;
  99                 //  case AtomicOrdering::Consume:         // not specified yet
 100                 //    return AtomicOrderingCABI::consume;
 101                 case AtomicOrdering::Acquire:
 102                         return (int)AtomicOrderingCABI::acquire;
 103                 case AtomicOrdering::Release:
 104                         return (int)AtomicOrderingCABI::release;
 105                 case AtomicOrdering::AcquireRelease:
 106                         return (int)AtomicOrderingCABI::acq_rel;
 107                 case AtomicOrdering::SequentiallyConsistent:
 108                         return (int)AtomicOrderingCABI::seq_cst;
 109                 default:
 110                         // unordered or Not Atomic
 111                         return -1;
 112         }
 113 }
 114
 115 AtomicOrderingCABI indexToAtomicOrder(int index) {
 116         switch (index) {
 117                 case 0:
 118                         return AtomicOrderingCABI::relaxed;
 119                 case 1:
 120                         return AtomicOrderingCABI::consume;
 121                 case 2:
 122                         return AtomicOrderingCABI::acquire;
 123                 case 3:
 124                         return AtomicOrderingCABI::release;
 125                 case 4:
 126                         return AtomicOrderingCABI::acq_rel;
 127                 case 5:
 128                         return AtomicOrderingCABI::seq_cst;
 129                 default:
 130                         errs() << "Bad Atomic index\n";
 131                         return AtomicOrderingCABI::seq_cst;
 132         }
 133 }
 134
 135 /* According to atomic_base.h: __cmpexch_failure_order */
 136 int AtomicCasFailureOrderIndex(int index) {
 137         AtomicOrderingCABI succ_order = indexToAtomicOrder(index);
 138         AtomicOrderingCABI fail_order;
 139         if (succ_order == AtomicOrderingCABI::acq_rel)
 140                 fail_order = AtomicOrderingCABI::acquire;
 141         else if (succ_order == AtomicOrderingCABI::release)
 142                 fail_order = AtomicOrderingCABI::relaxed;
 143         else
 144                 fail_order = succ_order;
 145
 146         return (int) fail_order;
 147 }
 148
 149 /* The original function checkSanitizerInterfaceFunction was defined
 150  * in llvm/Transforms/Utils/ModuleUtils.h
 151  */
 152 static Function * checkCDSPassInterfaceFunction(Constant *FuncOrBitcast) {
 153         if (isa<Function>(FuncOrBitcast))
 154                 return cast<Function>(FuncOrBitcast);
 155         FuncOrBitcast->print(errs());
 156         errs() << '\n';
 157         std::string Err;
 158         raw_string_ostream Stream(Err);
 159         Stream << "CDSPass interface function redefined: " << *FuncOrBitcast;
 160         report_fatal_error(Err);
 161 }
 162
 163 namespace {
 164         struct CDSPass : public FunctionPass {
 165                 CDSPass() : FunctionPass(ID) {}
 166                 StringRef getPassName() const override;
 167                 bool runOnFunction(Function &F) override;
 168                 bool doInitialization(Module &M) override;
 169                 static char ID;
 170
 171         private:
 172                 void initializeCallbacks(Module &M);
 173                 bool instrumentLoadOrStore(Instruction *I, const DataLayout &DL);
 174                 bool instrumentVolatile(Instruction *I, const DataLayout &DL);
 175                 bool isAtomicCall(Instruction *I);
 176                 bool instrumentAtomic(Instruction *I, const DataLayout &DL);
 177                 bool instrumentAtomicCall(CallInst *CI, const DataLayout &DL);
 178                 void chooseInstructionsToInstrument(SmallVectorImpl<Instruction *> &Local,
 179                                                                                         SmallVectorImpl<Instruction *> &All,
 180                                                                                         const DataLayout &DL);
 181                 bool addrPointsToConstantData(Value *Addr);
 182                 int getMemoryAccessFuncIndex(Value *Addr, const DataLayout &DL);
 183
 184                 Function * CDSFuncEntry;
 185                 Function * CDSFuncExit;
 186
 187                 Function * CDSLoad[kNumberOfAccessSizes];
 188                 Function * CDSStore[kNumberOfAccessSizes];
 189                 Function * CDSVolatileLoad[kNumberOfAccessSizes];
 190                 Function * CDSVolatileStore[kNumberOfAccessSizes];
 191                 Function * CDSAtomicInit[kNumberOfAccessSizes];
 192                 Function * CDSAtomicLoad[kNumberOfAccessSizes];
 193                 Function * CDSAtomicStore[kNumberOfAccessSizes];
 194                 Function * CDSAtomicRMW[AtomicRMWInst::LAST_BINOP + 1][kNumberOfAccessSizes];
 195                 Function * CDSAtomicCAS_V1[kNumberOfAccessSizes];
 196                 Function * CDSAtomicCAS_V2[kNumberOfAccessSizes];
 197                 Function * CDSAtomicThreadFence;
 198                 Function * CDSCtorFunction;
 199
 200                 std::vector<StringRef> AtomicFuncNames;
 201                 std::vector<StringRef> PartialAtomicFuncNames;
 202         };
 203 }
 204
 205 StringRef CDSPass::getPassName() const {
 206         return "CDSPass";
 207 }
 208
 209 void CDSPass::initializeCallbacks(Module &M) {
 210         LLVMContext &Ctx = M.getContext();
 211
 212         Type * Int1Ty = Type::getInt1Ty(Ctx);
 213         OrdTy = Type::getInt32Ty(Ctx);
 214
 215         Int8PtrTy  = Type::getInt8PtrTy(Ctx);
 216         Int16PtrTy = Type::getInt16PtrTy(Ctx);
 217         Int32PtrTy = Type::getInt32PtrTy(Ctx);
 218         Int64PtrTy = Type::getInt64PtrTy(Ctx);
 219
 220         VoidTy = Type::getVoidTy(Ctx);
 221
 222         CDSFuncEntry = checkCDSPassInterfaceFunction(
 223                                                 M.getOrInsertFunction("cds_func_entry",
 224                                                 VoidTy, Int8PtrTy));
 225         CDSFuncExit = checkCDSPassInterfaceFunction(
 226                                                 M.getOrInsertFunction("cds_func_exit",
 227                                                 VoidTy, Int8PtrTy));
 228
 229         // Get the function to call from our untime library.
 230         for (unsigned i = 0; i < kNumberOfAccessSizes; i++) {
 231                 const unsigned ByteSize = 1U << i;
 232                 const unsigned BitSize = ByteSize * 8;
 233
 234                 std::string ByteSizeStr = utostr(ByteSize);
 235                 std::string BitSizeStr = utostr(BitSize);
 236
 237                 Type *Ty = Type::getIntNTy(Ctx, BitSize);
 238                 Type *PtrTy = Ty->getPointerTo();
 239
 240                 // uint8_t cds_atomic_load8 (void * obj, int atomic_index)
 241                 // void cds_atomic_store8 (void * obj, int atomic_index, uint8_t val)
 242                 SmallString<32> LoadName("cds_load" + BitSizeStr);
 243                 SmallString<32> StoreName("cds_store" + BitSizeStr);
 244                 SmallString<32> VolatileLoadName("cds_volatile_load" + BitSizeStr);
 245                 SmallString<32> VolatileStoreName("cds_volatile_store" + BitSizeStr);
 246                 SmallString<32> AtomicInitName("cds_atomic_init" + BitSizeStr);
 247                 SmallString<32> AtomicLoadName("cds_atomic_load" + BitSizeStr);
 248                 SmallString<32> AtomicStoreName("cds_atomic_store" + BitSizeStr);
 249
 250                 CDSLoad[i]  = checkCDSPassInterfaceFunction(
 251                                                         M.getOrInsertFunction(LoadName, VoidTy, PtrTy));
 252                 CDSStore[i] = checkCDSPassInterfaceFunction(
 253                                                         M.getOrInsertFunction(StoreName, VoidTy, PtrTy));
 254                 CDSVolatileLoad[i]  = checkCDSPassInterfaceFunction(
 255                                                                 M.getOrInsertFunction(VolatileLoadName,
 256                                                                 Ty, PtrTy, Int8PtrTy));
 257                 CDSVolatileStore[i] = checkCDSPassInterfaceFunction(
 258                                                                 M.getOrInsertFunction(VolatileStoreName,
 259                                                                 VoidTy, PtrTy, Ty, Int8PtrTy));
 260                 CDSAtomicInit[i] = checkCDSPassInterfaceFunction(
 261                                                         M.getOrInsertFunction(AtomicInitName,
 262                                                         VoidTy, PtrTy, Ty, Int8PtrTy));
 263                 CDSAtomicLoad[i]  = checkCDSPassInterfaceFunction(
 264                                                                 M.getOrInsertFunction(AtomicLoadName,
 265                                                                 Ty, PtrTy, OrdTy, Int8PtrTy));
 266                 CDSAtomicStore[i] = checkCDSPassInterfaceFunction(
 267                                                                 M.getOrInsertFunction(AtomicStoreName,
 268                                                                 VoidTy, PtrTy, Ty, OrdTy, Int8PtrTy));
 269
 270                 for (int op = AtomicRMWInst::FIRST_BINOP;
 271                         op <= AtomicRMWInst::LAST_BINOP; ++op) {
 272                         CDSAtomicRMW[op][i] = nullptr;
 273                         std::string NamePart;
 274
 275                         if (op == AtomicRMWInst::Xchg)
 276                                 NamePart = "_exchange";
 277                         else if (op == AtomicRMWInst::Add)
 278                                 NamePart = "_fetch_add";
 279                         else if (op == AtomicRMWInst::Sub)
 280                                 NamePart = "_fetch_sub";
 281                         else if (op == AtomicRMWInst::And)
 282                                 NamePart = "_fetch_and";
 283                         else if (op == AtomicRMWInst::Or)
 284                                 NamePart = "_fetch_or";
 285                         else if (op == AtomicRMWInst::Xor)
 286                                 NamePart = "_fetch_xor";
 287                         else
 288                                 continue;
 289
 290                         SmallString<32> AtomicRMWName("cds_atomic" + NamePart + BitSizeStr);
 291                         CDSAtomicRMW[op][i] = checkCDSPassInterfaceFunction(
 292                                                                         M.getOrInsertFunction(AtomicRMWName,
 293                                                                         Ty, PtrTy, Ty, OrdTy, Int8PtrTy));
 294                 }
 295
 296                 // only supportes strong version
 297                 SmallString<32> AtomicCASName_V1("cds_atomic_compare_exchange" + BitSizeStr + "_v1");
 298                 SmallString<32> AtomicCASName_V2("cds_atomic_compare_exchange" + BitSizeStr + "_v2");
 299                 CDSAtomicCAS_V1[i] = checkCDSPassInterfaceFunction(
 300                                                                 M.getOrInsertFunction(AtomicCASName_V1,
 301                                                                 Ty, PtrTy, Ty, Ty, OrdTy, OrdTy, Int8PtrTy));
 302                 CDSAtomicCAS_V2[i] = checkCDSPassInterfaceFunction(
 303                                                                 M.getOrInsertFunction(AtomicCASName_V2,
 304                                                                 Int1Ty, PtrTy, PtrTy, Ty, OrdTy, OrdTy, Int8PtrTy));
 305         }
 306
 307         CDSAtomicThreadFence = checkCDSPassInterfaceFunction(
 308                                                                 M.getOrInsertFunction("cds_atomic_thread_fence",
 309                                                                 VoidTy, OrdTy, Int8PtrTy));
 310 }
 311
 312 bool CDSPass::doInitialization(Module &M) {
 313         const DataLayout &DL = M.getDataLayout();
 314         IntPtrTy = DL.getIntPtrType(M.getContext());
 315
 316         // createSanitizerCtorAndInitFunctions is defined in "llvm/Transforms/Utils/ModuleUtils.h"
 317         // We do not support it yet
 318         /*
 319         std::tie(CDSCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
 320                         M, kCDSModuleCtorName, kCDSInitName, {}, {});
 321
 322         appendToGlobalCtors(M, CDSCtorFunction, 0);
 323         */
 324
 325         AtomicFuncNames =
 326         {
 327                 "atomic_init", "atomic_load", "atomic_store",
 328                 "atomic_fetch_", "atomic_exchange", "atomic_compare_exchange_"
 329         };
 330
 331         PartialAtomicFuncNames =
 332         {
 333                 "load", "store", "fetch", "exchange", "compare_exchange_"
 334         };
 335
 336         return true;
 337 }
 338
 339 static bool isVtableAccess(Instruction *I) {
 340         if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa))
 341                 return Tag->isTBAAVtableAccess();
 342         return false;
 343 }
 344
 345 // Do not instrument known races/"benign races" that come from compiler
 346 // instrumentatin. The user has no way of suppressing them.
 347 static bool shouldInstrumentReadWriteFromAddress(const Module *M, Value *Addr) {
 348         // Peel off GEPs and BitCasts.
 349         Addr = Addr->stripInBoundsOffsets();
 350
 351         if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
 352                 if (GV->hasSection()) {
 353                         StringRef SectionName = GV->getSection();
 354                         // Check if the global is in the PGO counters section.
 355                         auto OF = Triple(M->getTargetTriple()).getObjectFormat();
 356                         if (SectionName.endswith(
 357                               getInstrProfSectionName(IPSK_cnts, OF, /*AddSegmentInfo=*/false)))
 358                                 return false;
 359                 }
 360
 361                 // Check if the global is private gcov data.
 362                 if (GV->getName().startswith("__llvm_gcov") ||
 363                 GV->getName().startswith("__llvm_gcda"))
 364                 return false;
 365         }
 366
 367         // Do not instrument acesses from different address spaces; we cannot deal
 368         // with them.
 369         if (Addr) {
 370                 Type *PtrTy = cast<PointerType>(Addr->getType()->getScalarType());
 371                 if (PtrTy->getPointerAddressSpace() != 0)
 372                         return false;
 373         }
 374
 375         return true;
 376 }
 377
 378 bool CDSPass::addrPointsToConstantData(Value *Addr) {
 379         // If this is a GEP, just analyze its pointer operand.
 380         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Addr))
 381                 Addr = GEP->getPointerOperand();
 382
 383         if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
 384                 if (GV->isConstant()) {
 385                         // Reads from constant globals can not race with any writes.
 386                         NumOmittedReadsFromConstantGlobals++;
 387                         return true;
 388                 }
 389         } else if (LoadInst *L = dyn_cast<LoadInst>(Addr)) {
 390                 if (isVtableAccess(L)) {
 391                         // Reads from a vtable pointer can not race with any writes.
 392                         NumOmittedReadsFromVtable++;
 393                         return true;
 394                 }
 395         }
 396         return false;
 397 }
 398
 399 void CDSPass::chooseInstructionsToInstrument(
 400         SmallVectorImpl<Instruction *> &Local, SmallVectorImpl<Instruction *> &All,
 401         const DataLayout &DL) {
 402         SmallPtrSet<Value*, 8> WriteTargets;
 403         // Iterate from the end.
 404         for (Instruction *I : reverse(Local)) {
 405                 if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
 406                         Value *Addr = Store->getPointerOperand();
 407                         if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
 408                                 continue;
 409                         WriteTargets.insert(Addr);
 410                 } else {
 411                         LoadInst *Load = cast<LoadInst>(I);
 412                         Value *Addr = Load->getPointerOperand();
 413                         if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
 414                                 continue;
 415                         if (WriteTargets.count(Addr)) {
 416                                 // We will write to this temp, so no reason to analyze the read.
 417                                 NumOmittedReadsBeforeWrite++;
 418                                 continue;
 419                         }
 420                         if (addrPointsToConstantData(Addr)) {
 421                                 // Addr points to some constant data -- it can not race with any writes.
 422                                 continue;
 423                         }
 424                 }
 425                 Value *Addr = isa<StoreInst>(*I)
 426                         ? cast<StoreInst>(I)->getPointerOperand()
 427                         : cast<LoadInst>(I)->getPointerOperand();
 428                 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
 429                                 !PointerMayBeCaptured(Addr, true, true)) {
 430                         // The variable is addressable but not captured, so it cannot be
 431                         // referenced from a different thread and participate in a data race
 432                         // (see llvm/Analysis/CaptureTracking.h for details).
 433                         NumOmittedNonCaptured++;
 434                         continue;
 435                 }
 436                 All.push_back(I);
 437         }
 438         Local.clear();
 439 }
 440
 441 /* Not implemented
 442 void CDSPass::InsertRuntimeIgnores(Function &F) {
 443         IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
 444         IRB.CreateCall(CDSIgnoreBegin);
 445         EscapeEnumerator EE(F, "cds_ignore_cleanup", ClHandleCxxExceptions);
 446         while (IRBuilder<> *AtExit = EE.Next()) {
 447                 AtExit->CreateCall(CDSIgnoreEnd);
 448         }
 449 }*/
 450
 451 bool CDSPass::runOnFunction(Function &F) {
 452         if (F.getName() == "main") {
 453                 F.setName("user_main");
 454                 errs() << "main replaced by user_main\n";
 455         }
 456
 457         initializeCallbacks( *F.getParent() );
 458         SmallVector<Instruction*, 8> AllLoadsAndStores;
 459         SmallVector<Instruction*, 8> LocalLoadsAndStores;
 460         SmallVector<Instruction*, 8> VolatileLoadsAndStores;
 461         SmallVector<Instruction*, 8> AtomicAccesses;
 462
 463         bool Res = false;
 464         bool HasCall = false;
 465         bool HasAtomic = false;
 466         bool HasVolatile = false;
 467         const DataLayout &DL = F.getParent()->getDataLayout();
 468
 469         for (auto &BB : F) {
 470                 for (auto &Inst : BB) {
 471                         if ( (&Inst)->isAtomic() || isAtomicCall(&Inst) ) {
 472                                 AtomicAccesses.push_back(&Inst);
 473                                 HasAtomic = true;
 474                         } else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst)) {
 475                                 LoadInst *LI = dyn_cast<LoadInst>(&Inst);
 476                                 StoreInst *SI = dyn_cast<StoreInst>(&Inst);
 477                                 bool isVolatile = ( LI ? LI->isVolatile() : SI->isVolatile() );
 478
 479                                 if (isVolatile) {
 480                                         VolatileLoadsAndStores.push_back(&Inst);
 481                                         HasVolatile = true;
 482                                 } else
 483                                         LocalLoadsAndStores.push_back(&Inst);
 484                         } else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) {
 485                                 /* TODO: To be added
 486                                 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
 487                                         maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
 488                                 if (isa<MemIntrinsic>(Inst))
 489                                         MemIntrinCalls.push_back(&Inst);
 490                                 HasCalls = true;
 491                                 chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores,
 492                                         DL);
 493                                 */
 494                         }
 495                 }
 496
 497                 chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores, DL);
 498         }
 499
 500         for (auto Inst : AllLoadsAndStores) {
 501                 Res |= instrumentLoadOrStore(Inst, DL);
 502         }
 503
 504         for (auto Inst : VolatileLoadsAndStores) {
 505                 Res |= instrumentVolatile(Inst, DL);
 506         }
 507
 508         for (auto Inst : AtomicAccesses) {
 509                 Res |= instrumentAtomic(Inst, DL);
 510         }
 511
 512         /* TODO
 513         for (auto Inst : MemIntrinCalls) {
 514                 Res |= instrumentMemIntrinsic(Inst);
 515         }
 516         */
 517
 518         // Only instrument functions that contain atomics or volatiles
 519         if (Res && ( HasAtomic || HasVolatile) ) {
 520                 IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
 521                 /* Unused for now
 522                 Value *ReturnAddress = IRB.CreateCall(
 523                         Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
 524                         IRB.getInt32(0));
 525                 */
 526
 527                 Value * FuncName = IRB.CreateGlobalStringPtr(F.getName());
 528                 IRB.CreateCall(CDSFuncEntry, FuncName);
 529
 530                 EscapeEnumerator EE(F, "cds_cleanup", true);
 531                 while (IRBuilder<> *AtExit = EE.Next()) {
 532                   AtExit->CreateCall(CDSFuncExit, FuncName);
 533                 }
 534
 535                 Res = true;
 536         }
 537
 538         return false;
 539 }
 540
 541 bool CDSPass::instrumentLoadOrStore(Instruction *I,
 542                                                                         const DataLayout &DL) {
 543         IRBuilder<> IRB(I);
 544         bool IsWrite = isa<StoreInst>(*I);
 545         Value *Addr = IsWrite
 546                 ? cast<StoreInst>(I)->getPointerOperand()
 547                 : cast<LoadInst>(I)->getPointerOperand();
 548
 549         // swifterror memory addresses are mem2reg promoted by instruction selection.
 550         // As such they cannot have regular uses like an instrumentation function and
 551         // it makes no sense to track them as memory.
 552         if (Addr->isSwiftError())
 553         return false;
 554
 555         int Idx = getMemoryAccessFuncIndex(Addr, DL);
 556         if (Idx < 0)
 557                 return false;
 558
 559 //  not supported by CDS yet
 560 /*  if (IsWrite && isVtableAccess(I)) {
 561     LLVM_DEBUG(dbgs() << "  VPTR : " << *I << "\n");
 562     Value *StoredValue = cast<StoreInst>(I)->getValueOperand();
 563     // StoredValue may be a vector type if we are storing several vptrs at once.
 564     // In this case, just take the first element of the vector since this is
 565     // enough to find vptr races.
 566     if (isa<VectorType>(StoredValue->getType()))
 567       StoredValue = IRB.CreateExtractElement(
 568           StoredValue, ConstantInt::get(IRB.getInt32Ty(), 0));
 569     if (StoredValue->getType()->isIntegerTy())
 570       StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
 571     // Call TsanVptrUpdate.
 572     IRB.CreateCall(TsanVptrUpdate,
 573                    {IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
 574                     IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy())});
 575     NumInstrumentedVtableWrites++;
 576     return true;
 577   }
 578
 579   if (!IsWrite && isVtableAccess(I)) {
 580     IRB.CreateCall(TsanVptrLoad,
 581                    IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
 582     NumInstrumentedVtableReads++;
 583     return true;
 584   }
 585 */
 586
 587         Value *OnAccessFunc = nullptr;
 588         OnAccessFunc = IsWrite ? CDSStore[Idx] : CDSLoad[Idx];
 589
 590         Type *ArgType = IRB.CreatePointerCast(Addr, Addr->getType())->getType();
 591
 592         if ( ArgType != Int8PtrTy && ArgType != Int16PtrTy &&
 593                         ArgType != Int32PtrTy && ArgType != Int64PtrTy ) {
 594                 // if other types of load or stores are passed in
 595                 return false;
 596         }
 597
 598         IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, Addr->getType()));
 599         if (IsWrite) NumInstrumentedWrites++;
 600         else         NumInstrumentedReads++;
 601         return true;
 602 }
 603
 604 bool CDSPass::instrumentVolatile(Instruction * I, const DataLayout &DL) {
 605         IRBuilder<> IRB(I);
 606         Value *position = getPosition(I, IRB);
 607
 608         if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
 609                 assert( LI->isVolatile() );
 610                 Value *Addr = LI->getPointerOperand();
 611                 int Idx=getMemoryAccessFuncIndex(Addr, DL);
 612                 if (Idx < 0)
 613                         return false;
 614
 615                 Value *args[] = {Addr, position};
 616                 Instruction* funcInst = CallInst::Create(CDSVolatileLoad[Idx], args);
 617                 ReplaceInstWithInst(LI, funcInst);
 618         } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
 619                 assert( SI->isVolatile() );
 620                 Value *Addr = SI->getPointerOperand();
 621                 int Idx=getMemoryAccessFuncIndex(Addr, DL);
 622                 if (Idx < 0)
 623                         return false;
 624
 625                 Value *val = SI->getValueOperand();
 626                 Value *args[] = {Addr, val, position};
 627                 Instruction* funcInst = CallInst::Create(CDSVolatileStore[Idx], args);
 628                 ReplaceInstWithInst(SI, funcInst);
 629         } else {
 630                 return false;
 631         }
 632
 633         return true;
 634 }
 635
 636 bool CDSPass::instrumentAtomic(Instruction * I, const DataLayout &DL) {
 637         IRBuilder<> IRB(I);
 638
 639         if (auto *CI = dyn_cast<CallInst>(I)) {
 640                 return instrumentAtomicCall(CI, DL);
 641         }
 642
 643         Value *position = getPosition(I, IRB);
 644
 645         if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
 646                 Value *Addr = LI->getPointerOperand();
 647                 int Idx=getMemoryAccessFuncIndex(Addr, DL);
 648                 if (Idx < 0)
 649                         return false;
 650
 651                 int atomic_order_index = getAtomicOrderIndex(LI->getOrdering());
 652                 Value *order = ConstantInt::get(OrdTy, atomic_order_index);
 653                 Value *args[] = {Addr, order, position};
 654                 Instruction* funcInst = CallInst::Create(CDSAtomicLoad[Idx], args);
 655                 ReplaceInstWithInst(LI, funcInst);
 656         } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
 657                 Value *Addr = SI->getPointerOperand();
 658                 int Idx=getMemoryAccessFuncIndex(Addr, DL);
 659                 if (Idx < 0)
 660                         return false;
 661
 662                 int atomic_order_index = getAtomicOrderIndex(SI->getOrdering());
 663                 Value *val = SI->getValueOperand();
 664                 Value *order = ConstantInt::get(OrdTy, atomic_order_index);
 665                 Value *args[] = {Addr, val, order, position};
 666                 Instruction* funcInst = CallInst::Create(CDSAtomicStore[Idx], args);
 667                 ReplaceInstWithInst(SI, funcInst);
 668         } else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I)) {
 669                 Value *Addr = RMWI->getPointerOperand();
 670                 int Idx=getMemoryAccessFuncIndex(Addr, DL);
 671                 if (Idx < 0)
 672                         return false;
 673
 674                 int atomic_order_index = getAtomicOrderIndex(RMWI->getOrdering());
 675                 Value *val = RMWI->getValOperand();
 676                 Value *order = ConstantInt::get(OrdTy, atomic_order_index);
 677                 Value *args[] = {Addr, val, order, position};
 678                 Instruction* funcInst = CallInst::Create(CDSAtomicRMW[RMWI->getOperation()][Idx], args);
 679                 ReplaceInstWithInst(RMWI, funcInst);
 680         } else if (AtomicCmpXchgInst *CASI = dyn_cast<AtomicCmpXchgInst>(I)) {
 681                 IRBuilder<> IRB(CASI);
 682
 683                 Value *Addr = CASI->getPointerOperand();
 684                 int Idx=getMemoryAccessFuncIndex(Addr, DL);
 685                 if (Idx < 0)
 686                         return false;
 687
 688                 const unsigned ByteSize = 1U << Idx;
 689                 const unsigned BitSize = ByteSize * 8;
 690                 Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
 691                 Type *PtrTy = Ty->getPointerTo();
 692
 693                 Value *CmpOperand = IRB.CreateBitOrPointerCast(CASI->getCompareOperand(), Ty);
 694                 Value *NewOperand = IRB.CreateBitOrPointerCast(CASI->getNewValOperand(), Ty);
 695
 696                 int atomic_order_index_succ = getAtomicOrderIndex(CASI->getSuccessOrdering());
 697                 int atomic_order_index_fail = getAtomicOrderIndex(CASI->getFailureOrdering());
 698                 Value *order_succ = ConstantInt::get(OrdTy, atomic_order_index_succ);
 699                 Value *order_fail = ConstantInt::get(OrdTy, atomic_order_index_fail);
 700
 701                 Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
 702                                                  CmpOperand, NewOperand,
 703                                                  order_succ, order_fail, position};
 704
 705                 CallInst *funcInst = IRB.CreateCall(CDSAtomicCAS_V1[Idx], Args);
 706                 Value *Success = IRB.CreateICmpEQ(funcInst, CmpOperand);
 707
 708                 Value *OldVal = funcInst;
 709                 Type *OrigOldValTy = CASI->getNewValOperand()->getType();
 710                 if (Ty != OrigOldValTy) {
 711                         // The value is a pointer, so we need to cast the return value.
 712                         OldVal = IRB.CreateIntToPtr(funcInst, OrigOldValTy);
 713                 }
 714
 715                 Value *Res =
 716                   IRB.CreateInsertValue(UndefValue::get(CASI->getType()), OldVal, 0);
 717                 Res = IRB.CreateInsertValue(Res, Success, 1);
 718
 719                 I->replaceAllUsesWith(Res);
 720                 I->eraseFromParent();
 721         } else if (FenceInst *FI = dyn_cast<FenceInst>(I)) {
 722                 int atomic_order_index = getAtomicOrderIndex(FI->getOrdering());
 723                 Value *order = ConstantInt::get(OrdTy, atomic_order_index);
 724                 Value *Args[] = {order, position};
 725
 726                 CallInst *funcInst = CallInst::Create(CDSAtomicThreadFence, Args);
 727                 ReplaceInstWithInst(FI, funcInst);
 728                 // errs() << "Thread Fences replaced\n";
 729         }
 730         return true;
 731 }
 732
 733 bool CDSPass::isAtomicCall(Instruction *I) {
 734         if ( auto *CI = dyn_cast<CallInst>(I) ) {
 735                 Function *fun = CI->getCalledFunction();
 736                 if (fun == NULL)
 737                         return false;
 738
 739                 StringRef funName = fun->getName();
 740
 741                 // todo: come up with better rules for function name checking
 742                 for (StringRef name : AtomicFuncNames) {
 743                         if ( funName.contains(name) )
 744                                 return true;
 745                 }
 746
 747                 for (StringRef PartialName : PartialAtomicFuncNames) {
 748                         if (funName.contains(PartialName) &&
 749                                         funName.contains("atomic") )
 750                                 return true;
 751                 }
 752         }
 753
 754         return false;
 755 }
 756
 757 bool CDSPass::instrumentAtomicCall(CallInst *CI, const DataLayout &DL) {
 758         IRBuilder<> IRB(CI);
 759         Function *fun = CI->getCalledFunction();
 760         StringRef funName = fun->getName();
 761         std::vector<Value *> parameters;
 762
 763         User::op_iterator begin = CI->arg_begin();
 764         User::op_iterator end = CI->arg_end();
 765         for (User::op_iterator it = begin; it != end; ++it) {
 766                 Value *param = *it;
 767                 parameters.push_back(param);
 768         }
 769
 770         // obtain source line number of the CallInst
 771         Value *position = getPosition(CI, IRB);
 772
 773         // the pointer to the address is always the first argument
 774         Value *OrigPtr = parameters[0];
 775
 776         int Idx = getMemoryAccessFuncIndex(OrigPtr, DL);
 777         if (Idx < 0)
 778                 return false;
 779
 780         const unsigned ByteSize = 1U << Idx;
 781         const unsigned BitSize = ByteSize * 8;
 782         Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
 783         Type *PtrTy = Ty->getPointerTo();
 784
 785         // atomic_init; args = {obj, order}
 786         if (funName.contains("atomic_init")) {
 787                 Value *OrigVal = parameters[1];
 788
 789                 Value *ptr = IRB.CreatePointerCast(OrigPtr, PtrTy);
 790                 Value *val;
 791                 if (OrigVal->getType()->isPtrOrPtrVectorTy())
 792                         val = IRB.CreatePointerCast(OrigVal, Ty);
 793                 else
 794                         val = IRB.CreateIntCast(OrigVal, Ty, true);
 795
 796                 Value *args[] = {ptr, val, position};
 797
 798                 Instruction* funcInst = CallInst::Create(CDSAtomicInit[Idx], args);
 799                 ReplaceInstWithInst(CI, funcInst);
 800
 801                 return true;
 802         }
 803
 804         // atomic_load; args = {obj, order}
 805         if (funName.contains("atomic_load")) {
 806                 bool isExplicit = funName.contains("atomic_load_explicit");
 807
 808                 Value *ptr = IRB.CreatePointerCast(OrigPtr, PtrTy);
 809                 Value *order;
 810                 if (isExplicit)
 811                         order = IRB.CreateBitOrPointerCast(parameters[1], OrdTy);
 812                 else
 813                         order = ConstantInt::get(OrdTy,
 814                                                         (int) AtomicOrderingCABI::seq_cst);
 815                 Value *args[] = {ptr, order, position};
 816
 817                 Instruction* funcInst = CallInst::Create(CDSAtomicLoad[Idx], args);
 818                 ReplaceInstWithInst(CI, funcInst);
 819
 820                 return true;
 821         } else if (funName.contains("atomic") &&
 822                                         funName.contains("load") ) {
 823                 // does this version of call always have an atomic order as an argument?
 824                 Value *ptr = IRB.CreatePointerCast(OrigPtr, PtrTy);
 825                 Value *order = IRB.CreateBitOrPointerCast(parameters[1], OrdTy);
 826                 Value *args[] = {ptr, order, position};
 827
 828                 if (!CI->getType()->isPointerTy()) {
 829                         return false;
 830                 }
 831
 832                 CallInst *funcInst = IRB.CreateCall(CDSAtomicLoad[Idx], args);
 833                 Value *RetVal = IRB.CreateIntToPtr(funcInst, CI->getType());
 834
 835                 CI->replaceAllUsesWith(RetVal);
 836                 CI->eraseFromParent();
 837
 838                 return true;
 839         }
 840
 841         // atomic_store; args = {obj, val, order}
 842         if (funName.contains("atomic_store")) {
 843                 bool isExplicit = funName.contains("atomic_store_explicit");
 844                 Value *OrigVal = parameters[1];
 845
 846                 Value *ptr = IRB.CreatePointerCast(OrigPtr, PtrTy);
 847                 Value *val = IRB.CreatePointerCast(OrigVal, Ty);
 848                 Value *order;
 849                 if (isExplicit)
 850                         order = IRB.CreateBitOrPointerCast(parameters[2], OrdTy);
 851                 else
 852                         order = ConstantInt::get(OrdTy,
 853                                                         (int) AtomicOrderingCABI::seq_cst);
 854                 Value *args[] = {ptr, val, order, position};
 855
 856                 Instruction* funcInst = CallInst::Create(CDSAtomicStore[Idx], args);
 857                 ReplaceInstWithInst(CI, funcInst);
 858
 859                 return true;
 860         } else if (funName.contains("atomic") &&
 861                                         funName.contains("store") ) {
 862                 // does this version of call always have an atomic order as an argument?
 863                 Value *OrigVal = parameters[1];
 864
 865                 Value *ptr = IRB.CreatePointerCast(OrigPtr, PtrTy);
 866                 Value *val;
 867                 if (OrigVal->getType()->isPtrOrPtrVectorTy())
 868                         val = IRB.CreatePointerCast(OrigVal, Ty);
 869                 else
 870                         val = IRB.CreateIntCast(OrigVal, Ty, true);
 871
 872                 Value *order = IRB.CreateBitOrPointerCast(parameters[2], OrdTy);
 873                 Value *args[] = {ptr, val, order, position};
 874
 875                 Instruction* funcInst = CallInst::Create(CDSAtomicStore[Idx], args);
 876                 ReplaceInstWithInst(CI, funcInst);
 877
 878                 return true;
 879         }
 880
 881         // atomic_fetch_*; args = {obj, val, order}
 882         if (funName.contains("atomic_fetch_") ||
 883                 funName.contains("atomic_exchange")) {
 884
 885                 /* TODO: implement stricter function name checking */
 886                 if (funName.contains("non"))
 887                         return false;
 888
 889                 bool isExplicit = funName.contains("_explicit");
 890                 Value *OrigVal = parameters[1];
 891
 892                 int op;
 893                 if ( funName.contains("_fetch_add") )
 894                         op = AtomicRMWInst::Add;
 895                 else if ( funName.contains("_fetch_sub") )
 896                         op = AtomicRMWInst::Sub;
 897                 else if ( funName.contains("_fetch_and") )
 898                         op = AtomicRMWInst::And;
 899                 else if ( funName.contains("_fetch_or") )
 900                         op = AtomicRMWInst::Or;
 901                 else if ( funName.contains("_fetch_xor") )
 902                         op = AtomicRMWInst::Xor;
 903                 else if ( funName.contains("atomic_exchange") )
 904                         op = AtomicRMWInst::Xchg;
 905                 else {
 906                         errs() << "Unknown atomic read-modify-write operation\n";
 907                         return false;
 908                 }
 909
 910                 Value *ptr = IRB.CreatePointerCast(OrigPtr, PtrTy);
 911                 Value *val;
 912                 if (OrigVal->getType()->isPtrOrPtrVectorTy())
 913                         val = IRB.CreatePointerCast(OrigVal, Ty);
 914                 else
 915                         val = IRB.CreateIntCast(OrigVal, Ty, true);
 916
 917                 Value *order;
 918                 if (isExplicit)
 919                         order = IRB.CreateBitOrPointerCast(parameters[2], OrdTy);
 920                 else
 921                         order = ConstantInt::get(OrdTy,
 922                                                         (int) AtomicOrderingCABI::seq_cst);
 923                 Value *args[] = {ptr, val, order, position};
 924
 925                 Instruction* funcInst = CallInst::Create(CDSAtomicRMW[op][Idx], args);
 926                 ReplaceInstWithInst(CI, funcInst);
 927
 928                 return true;
 929         } else if (funName.contains("fetch")) {
 930                 errs() << "atomic fetch captured. Not implemented yet. ";
 931                 errs() << "See source file :";
 932                 getPosition(CI, IRB, true);
 933                 return false;
 934         } else if (funName.contains("exchange") &&
 935                         !funName.contains("compare_exchange") ) {
 936                 if (CI->getType()->isPointerTy()) {
 937                         // Can not deal with this now
 938                         errs() << "atomic exchange captured. Not implemented yet. ";
 939                         errs() << "See source file :";
 940                         getPosition(CI, IRB, true);
 941
 942                         return false;
 943                 }
 944
 945                 Value *OrigVal = parameters[1];
 946
 947                 Value *ptr = IRB.CreatePointerCast(OrigPtr, PtrTy);
 948                 Value *val;
 949                 if (OrigVal->getType()->isPtrOrPtrVectorTy())
 950                         val = IRB.CreatePointerCast(OrigVal, Ty);
 951                 else
 952                         val = IRB.CreateIntCast(OrigVal, Ty, true);
 953
 954                 Value *order = IRB.CreateBitOrPointerCast(parameters[2], OrdTy);
 955                 Value *args[] = {ptr, val, order, position};
 956                 int op = AtomicRMWInst::Xchg;
 957
 958                 Instruction* funcInst = CallInst::Create(CDSAtomicRMW[op][Idx], args);
 959                 ReplaceInstWithInst(CI, funcInst);
 960         }
 961
 962         /* atomic_compare_exchange_*;
 963            args = {obj, expected, new value, order1, order2}
 964         */
 965         if ( funName.contains("atomic_compare_exchange_") ) {
 966                 bool isExplicit = funName.contains("_explicit");
 967
 968                 Value *Addr = IRB.CreatePointerCast(OrigPtr, PtrTy);
 969                 Value *CmpOperand = IRB.CreatePointerCast(parameters[1], PtrTy);
 970                 Value *NewOperand = IRB.CreateBitOrPointerCast(parameters[2], Ty);
 971
 972                 Value *order_succ, *order_fail;
 973                 if (isExplicit) {
 974                         order_succ = IRB.CreateBitOrPointerCast(parameters[3], OrdTy);
 975
 976                         if (parameters.size() > 4) {
 977                                 order_fail = IRB.CreateBitOrPointerCast(parameters[4], OrdTy);
 978                         } else {
 979                                 /* The failure order is not provided */
 980                                 order_fail = order_succ;
 981                                 ConstantInt * order_succ_cast = dyn_cast<ConstantInt>(order_succ);
 982                                 int index = order_succ_cast->getSExtValue();
 983
 984                                 order_fail = ConstantInt::get(OrdTy,
 985                                                                 AtomicCasFailureOrderIndex(index));
 986                         }
 987                 } else  {
 988                         order_succ = ConstantInt::get(OrdTy,
 989                                                         (int) AtomicOrderingCABI::seq_cst);
 990                         order_fail = ConstantInt::get(OrdTy,
 991                                                         (int) AtomicOrderingCABI::seq_cst);
 992                 }
 993
 994                 Value *args[] = {Addr, CmpOperand, NewOperand,
 995                                                         order_succ, order_fail, position};
 996
 997                 Instruction* funcInst = CallInst::Create(CDSAtomicCAS_V2[Idx], args);
 998                 ReplaceInstWithInst(CI, funcInst);
 999
1000                 return true;
1001         } else if ( funName.contains("compare_exchange_strong") ||
1002                                 funName.contains("compare_exchange_weak") ) {
1003                 Value *Addr = IRB.CreatePointerCast(OrigPtr, PtrTy);
1004                 Value *CmpOperand = IRB.CreatePointerCast(parameters[1], PtrTy);
1005                 Value *NewOperand = IRB.CreateBitOrPointerCast(parameters[2], Ty);
1006
1007                 Value *order_succ, *order_fail;
1008                 order_succ = IRB.CreateBitOrPointerCast(parameters[3], OrdTy);
1009
1010                 if (parameters.size() > 4) {
1011                         order_fail = IRB.CreateBitOrPointerCast(parameters[4], OrdTy);
1012                 } else {
1013                         /* The failure order is not provided */
1014                         order_fail = order_succ;
1015                         ConstantInt * order_succ_cast = dyn_cast<ConstantInt>(order_succ);
1016                         int index = order_succ_cast->getSExtValue();
1017
1018                         order_fail = ConstantInt::get(OrdTy,
1019                                                         AtomicCasFailureOrderIndex(index));
1020                 }
1021
1022                 Value *args[] = {Addr, CmpOperand, NewOperand,
1023                                                         order_succ, order_fail, position};
1024                 Instruction* funcInst = CallInst::Create(CDSAtomicCAS_V2[Idx], args);
1025                 ReplaceInstWithInst(CI, funcInst);
1026
1027                 return true;
1028         }
1029
1030         return false;
1031 }
1032
1033 int CDSPass::getMemoryAccessFuncIndex(Value *Addr,
1034                                                                                 const DataLayout &DL) {
1035         Type *OrigPtrTy = Addr->getType();
1036         Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
1037         assert(OrigTy->isSized());
1038         uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
1039         if (TypeSize != 8  && TypeSize != 16 &&
1040                 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
1041                 NumAccessesWithBadSize++;
1042                 // Ignore all unusual sizes.
1043                 return -1;
1044         }
1045         size_t Idx = countTrailingZeros(TypeSize / 8);
1046         //assert(Idx < kNumberOfAccessSizes);
1047         if (Idx >= kNumberOfAccessSizes) {
1048                 return -1;
1049         }
1050         return Idx;
1051 }
1052
1053
1054 char CDSPass::ID = 0;
1055
1056 // Automatically enable the pass.
1057 static void registerCDSPass(const PassManagerBuilder &,
1058                                                         legacy::PassManagerBase &PM) {
1059         PM.add(new CDSPass());
1060 }
1061
1062 /* Enable the pass when opt level is greater than 0 */
1063 static RegisterStandardPasses
1064         RegisterMyPass1(PassManagerBuilder::EP_OptimizerLast,
1065 registerCDSPass);
1066
1067 /* Enable the pass when opt level is 0 */
1068 static RegisterStandardPasses
1069         RegisterMyPass2(PassManagerBuilder::EP_EnabledOnOptLevel0,
1070 registerCDSPass);