C++ StoreInst::getDebugLoc方法代码示例

///   store {atomic|volatile} T %val, T* %ptr memory_order, align sizeof(T)
/// becomes:
///   call void @llvm.nacl.atomic.store.i<size>(%val, %ptr, memory_order)
void AtomicVisitor::visitStoreInst(StoreInst &I) {
  return; // XXX EMSCRIPTEN
  if (I.isSimple())
    return;
  PointerHelper<StoreInst> PH(*this, I);
  const NaCl::AtomicIntrinsics::AtomicIntrinsic *Intrinsic =
      findAtomicIntrinsic(I, Intrinsic::nacl_atomic_store, PH.PET);
  checkAlignment(I, I.getAlignment(), PH.BitSize / CHAR_BIT);
  Value *V = I.getValueOperand();
  if (!V->getType()->isIntegerTy()) {
    // The store isn't of an integer type. We define atomics in terms of
    // integers, so bitcast the value to store to an integer of the
    // proper width.
    CastInst *Cast = createCast(I, V, Type::getIntNTy(C, PH.BitSize),
                                V->getName() + ".cast");
    Cast->setDebugLoc(I.getDebugLoc());
    V = Cast;
  }
  checkSizeMatchesType(I, PH.BitSize, V->getType());
  Value *Args[] = {V, PH.P, freezeMemoryOrder(I, I.getOrdering())};
  replaceInstructionWithIntrinsicCall(I, Intrinsic, PH.OriginalPET, PH.PET,
                                      Args);
}

//.........这里部分代码省略.........
  if (++PI != pred_end(DestBB))
    return false;

  // Bail out if all the relevant blocks aren't distinct (this can happen,
  // for example, if SI is in an infinite loop)
  if (StoreBB == DestBB || OtherBB == DestBB)
    return false;

  // Verify that the other block ends in a branch and is not otherwise empty.
  BasicBlock::iterator BBI(OtherBB->getTerminator());
  BranchInst *OtherBr = dyn_cast<BranchInst>(BBI);
  if (!OtherBr || BBI == OtherBB->begin())
    return false;

  // If the other block ends in an unconditional branch, check for the 'if then
  // else' case.  there is an instruction before the branch.
  StoreInst *OtherStore = nullptr;
  if (OtherBr->isUnconditional()) {
    --BBI;
    // Skip over debugging info.
    while (isa<DbgInfoIntrinsic>(BBI) ||
           (isa<BitCastInst>(BBI) && BBI->getType()->isPointerTy())) {
      if (BBI==OtherBB->begin())
        return false;
      --BBI;
    }
    // If this isn't a store, isn't a store to the same location, or is not the
    // right kind of store, bail out.
    OtherStore = dyn_cast<StoreInst>(BBI);
    if (!OtherStore || OtherStore->getOperand(1) != SI.getOperand(1) ||
        !SI.isSameOperationAs(OtherStore))
      return false;
  } else {
    // Otherwise, the other block ended with a conditional branch. If one of the
    // destinations is StoreBB, then we have the if/then case.
    if (OtherBr->getSuccessor(0) != StoreBB &&
        OtherBr->getSuccessor(1) != StoreBB)
      return false;

    // Okay, we know that OtherBr now goes to Dest and StoreBB, so this is an
    // if/then triangle.  See if there is a store to the same ptr as SI that
    // lives in OtherBB.
    for (;; --BBI) {
      // Check to see if we find the matching store.
      if ((OtherStore = dyn_cast<StoreInst>(BBI))) {
        if (OtherStore->getOperand(1) != SI.getOperand(1) ||
            !SI.isSameOperationAs(OtherStore))
          return false;
        break;
      }
      // If we find something that may be using or overwriting the stored
      // value, or if we run out of instructions, we can't do the xform.
      if (BBI->mayReadFromMemory() || BBI->mayWriteToMemory() ||
          BBI == OtherBB->begin())
        return false;
    }

    // In order to eliminate the store in OtherBr, we have to
    // make sure nothing reads or overwrites the stored value in
    // StoreBB.
    for (BasicBlock::iterator I = StoreBB->begin(); &*I != &SI; ++I) {
      // FIXME: This should really be AA driven.
      if (I->mayReadFromMemory() || I->mayWriteToMemory())
        return false;
    }
  }

  // Insert a PHI node now if we need it.
  Value *MergedVal = OtherStore->getOperand(0);
  if (MergedVal != SI.getOperand(0)) {
    PHINode *PN = PHINode::Create(MergedVal->getType(), 2, "storemerge");
    PN->addIncoming(SI.getOperand(0), SI.getParent());
    PN->addIncoming(OtherStore->getOperand(0), OtherBB);
    MergedVal = InsertNewInstBefore(PN, DestBB->front());
  }

  // Advance to a place where it is safe to insert the new store and
  // insert it.
  BBI = DestBB->getFirstInsertionPt();
  StoreInst *NewSI = new StoreInst(MergedVal, SI.getOperand(1),
                                   SI.isVolatile(),
                                   SI.getAlignment(),
                                   SI.getOrdering(),
                                   SI.getSynchScope());
  InsertNewInstBefore(NewSI, *BBI);
  NewSI->setDebugLoc(OtherStore->getDebugLoc());

  // If the two stores had AA tags, merge them.
  AAMDNodes AATags;
  SI.getAAMetadata(AATags);
  if (AATags) {
    OtherStore->getAAMetadata(AATags, /* Merge = */ true);
    NewSI->setAAMetadata(AATags);
  }

  // Nuke the old stores.
  EraseInstFromFunction(SI);
  EraseInstFromFunction(*OtherStore);
  return true;
}

/// Attempt to merge an objc_release with a store, load, and objc_retain to form
/// an objc_storeStrong. An objc_storeStrong:
///
///   objc_storeStrong(i8** %old_ptr, i8* new_value)
///
/// is equivalent to the following IR sequence:
///
///   ; Load old value.
///   %old_value = load i8** %old_ptr               (1)
///
///   ; Increment the new value and then release the old value. This must occur
///   ; in order in case old_value releases new_value in its destructor causing
///   ; us to potentially have a dangling ptr.
///   tail call i8* @objc_retain(i8* %new_value)    (2)
///   tail call void @objc_release(i8* %old_value)  (3)
///
///   ; Store the new_value into old_ptr
///   store i8* %new_value, i8** %old_ptr           (4)
///
/// The safety of this optimization is based around the following
/// considerations:
///
///  1. We are forming the store strong at the store. Thus to perform this
///     optimization it must be safe to move the retain, load, and release to
///     (4).
///  2. We need to make sure that any re-orderings of (1), (2), (3), (4) are
///     safe.
void ObjCARCContract::tryToContractReleaseIntoStoreStrong(Instruction *Release,
                                                          inst_iterator &Iter) {
  // See if we are releasing something that we just loaded.
  auto *Load = dyn_cast<LoadInst>(GetArgRCIdentityRoot(Release));
  if (!Load || !Load->isSimple())
    return;

  // For now, require everything to be in one basic block.
  BasicBlock *BB = Release->getParent();
  if (Load->getParent() != BB)
    return;

  // First scan down the BB from Load, looking for a store of the RCIdentityRoot
  // of Load's
  StoreInst *Store =
      findSafeStoreForStoreStrongContraction(Load, Release, PA, AA);
  // If we fail, bail.
  if (!Store)
    return;

  // Then find what new_value's RCIdentity Root is.
  Value *New = GetRCIdentityRoot(Store->getValueOperand());

  // Then walk up the BB and look for a retain on New without any intervening
  // instructions which conservatively might decrement ref counts.
  Instruction *Retain =
      findRetainForStoreStrongContraction(New, Store, Release, PA);

  // If we fail, bail.
  if (!Retain)
    return;

  Changed = true;
  ++NumStoreStrongs;

  DEBUG(
      llvm::dbgs() << "    Contracting retain, release into objc_storeStrong.\n"
                   << "        Old:\n"
                   << "            Store:   " << *Store << "\n"
                   << "            Release: " << *Release << "\n"
                   << "            Retain:  " << *Retain << "\n"
                   << "            Load:    " << *Load << "\n");

  LLVMContext &C = Release->getContext();
  Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
  Type *I8XX = PointerType::getUnqual(I8X);

  Value *Args[] = { Load->getPointerOperand(), New };
  if (Args[0]->getType() != I8XX)
    Args[0] = new BitCastInst(Args[0], I8XX, "", Store);
  if (Args[1]->getType() != I8X)
    Args[1] = new BitCastInst(Args[1], I8X, "", Store);
  Constant *Decl = EP.get(ARCRuntimeEntryPointKind::StoreStrong);
  CallInst *StoreStrong = CallInst::Create(Decl, Args, "", Store);
  StoreStrong->setDoesNotThrow();
  StoreStrong->setDebugLoc(Store->getDebugLoc());

  // We can't set the tail flag yet, because we haven't yet determined
  // whether there are any escaping allocas. Remember this call, so that
  // we can set the tail flag once we know it's safe.
  StoreStrongCalls.insert(StoreStrong);

  DEBUG(llvm::dbgs() << "        New Store Strong: " << *StoreStrong << "\n");

  if (&*Iter == Store) ++Iter;
  Store->eraseFromParent();
  Release->eraseFromParent();
  EraseInstruction(Retain);
  if (Load->use_empty())
    Load->eraseFromParent();
}

/// Attempt to merge an objc_release with a store, load, and objc_retain to form
/// an objc_storeStrong. This can be a little tricky because the instructions
/// don't always appear in order, and there may be unrelated intervening
/// instructions.
void ObjCARCContract::ContractRelease(Instruction *Release,
                                      inst_iterator &Iter) {
  LoadInst *Load = dyn_cast<LoadInst>(GetObjCArg(Release));
  if (!Load || !Load->isSimple()) return;

  // For now, require everything to be in one basic block.
  BasicBlock *BB = Release->getParent();
  if (Load->getParent() != BB) return;

  // Walk down to find the store and the release, which may be in either order.
  BasicBlock::iterator I = Load, End = BB->end();
  ++I;
  AliasAnalysis::Location Loc = AA->getLocation(Load);
  StoreInst *Store = 0;
  bool SawRelease = false;
  for (; !Store || !SawRelease; ++I) {
    if (I == End)
      return;

    Instruction *Inst = I;
    if (Inst == Release) {
      SawRelease = true;
      continue;
    }

    InstructionClass Class = GetBasicInstructionClass(Inst);

    // Unrelated retains are harmless.
    if (IsRetain(Class))
      continue;

    if (Store) {
      // The store is the point where we're going to put the objc_storeStrong,
      // so make sure there are no uses after it.
      if (CanUse(Inst, Load, PA, Class))
        return;
    } else if (AA->getModRefInfo(Inst, Loc) & AliasAnalysis::Mod) {
      // We are moving the load down to the store, so check for anything
      // else which writes to the memory between the load and the store.
      Store = dyn_cast<StoreInst>(Inst);
      if (!Store || !Store->isSimple()) return;
      if (Store->getPointerOperand() != Loc.Ptr) return;
    }
  }

  Value *New = StripPointerCastsAndObjCCalls(Store->getValueOperand());

  // Walk up to find the retain.
  I = Store;
  BasicBlock::iterator Begin = BB->begin();
  while (I != Begin && GetBasicInstructionClass(I) != IC_Retain)
    --I;
  Instruction *Retain = I;
  if (GetBasicInstructionClass(Retain) != IC_Retain) return;
  if (GetObjCArg(Retain) != New) return;

  Changed = true;
  ++NumStoreStrongs;

  LLVMContext &C = Release->getContext();
  Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
  Type *I8XX = PointerType::getUnqual(I8X);

  Value *Args[] = { Load->getPointerOperand(), New };
  if (Args[0]->getType() != I8XX)
    Args[0] = new BitCastInst(Args[0], I8XX, "", Store);
  if (Args[1]->getType() != I8X)
    Args[1] = new BitCastInst(Args[1], I8X, "", Store);
  CallInst *StoreStrong =
    CallInst::Create(getStoreStrongCallee(BB->getParent()->getParent()),
                     Args, "", Store);
  StoreStrong->setDoesNotThrow();
  StoreStrong->setDebugLoc(Store->getDebugLoc());

  // We can't set the tail flag yet, because we haven't yet determined
  // whether there are any escaping allocas. Remember this call, so that
  // we can set the tail flag once we know it's safe.
  StoreStrongCalls.insert(StoreStrong);

  if (&*Iter == Store) ++Iter;
  Store->eraseFromParent();
  Release->eraseFromParent();
  EraseInstruction(Retain);
  if (Load->use_empty())
    Load->eraseFromParent();
}