void CSDataRando::findArgNodes(Module &M) {
  // Create function equivalence classes from the global equivalence classes.
  EquivalenceClasses<const GlobalValue*> &GlobalECs = DSA->getGlobalECs();
  EquivalenceClasses<const Function*> FunctionECs;

  for (auto ei = GlobalECs.begin(), ee = GlobalECs.end(); ei != ee; ei++) {
    // Ignore non-leader values.
    if (!ei->isLeader()) { continue; }

    const Function *Leader = nullptr;
    for (auto mi = GlobalECs.member_begin(ei), me = GlobalECs.member_end();
         mi != me;
         mi++) {
      // Only look at functions.
      if (const Function *F = dyn_cast<Function>(*mi)) {
        if (Leader) {
          FunctionECs.unionSets(Leader, F);
        } else {
          Leader = FunctionECs.getOrInsertLeaderValue(F);
        }
      }
    }
  }

  // Make sure all Functions are part of an equivalence class. This is important
  // since non-address taken functions may not appear in GlobalECs.
  for (Function &F : M) {
    if (!F.isDeclaration()) {
      FunctionECs.insert(&F);
    }
  }

  // Go through all equivalence classes and determine the additional
  // arguments.
  for (auto ei = FunctionECs.begin(), ee = FunctionECs.end();ei != ee; ei++) {
    if (ei->isLeader()) {
      NumFunctionECs++;
      std::vector<const Function*> Functions;
      Functions.insert(Functions.end(), FunctionECs.member_begin(ei), FunctionECs.member_end());

      // If we can't safely replace uses of the function's address with its
      // clone's address then we can't safely transform indirect calls to this
      // equivalence class. We still find the arg nodes for each function to
      // replace direct calls to these functions.
      if (!DSA->canReplaceAddress(ei->getData())) {
        NumFunECsWithExternal++;
        for (const Function *F : Functions) {
          if (!F->isDeclaration()) {
            findFunctionArgNodes(F);
            FunctionInfo[F].CanReplaceAddress = false;
          }
        }
      } else {
        findFunctionArgNodes(Functions);
      }
    }
  }
}
Exemplo n.º 2
0
MapVector<Instruction *, uint64_t>
llvm::computeMinimumValueSizes(ArrayRef<BasicBlock *> Blocks, DemandedBits &DB,
                               const TargetTransformInfo *TTI) {

  // DemandedBits will give us every value's live-out bits. But we want
  // to ensure no extra casts would need to be inserted, so every DAG
  // of connected values must have the same minimum bitwidth.
  EquivalenceClasses<Value *> ECs;
  SmallVector<Value *, 16> Worklist;
  SmallPtrSet<Value *, 4> Roots;
  SmallPtrSet<Value *, 16> Visited;
  DenseMap<Value *, uint64_t> DBits;
  SmallPtrSet<Instruction *, 4> InstructionSet;
  MapVector<Instruction *, uint64_t> MinBWs;

  // Determine the roots. We work bottom-up, from truncs or icmps.
  bool SeenExtFromIllegalType = false;
  for (auto *BB : Blocks)
    for (auto &I : *BB) {
      InstructionSet.insert(&I);

      if (TTI && (isa<ZExtInst>(&I) || isa<SExtInst>(&I)) &&
          !TTI->isTypeLegal(I.getOperand(0)->getType()))
        SeenExtFromIllegalType = true;

      // Only deal with non-vector integers up to 64-bits wide.
      if ((isa<TruncInst>(&I) || isa<ICmpInst>(&I)) &&
          !I.getType()->isVectorTy() &&
          I.getOperand(0)->getType()->getScalarSizeInBits() <= 64) {
        // Don't make work for ourselves. If we know the loaded type is legal,
        // don't add it to the worklist.
        if (TTI && isa<TruncInst>(&I) && TTI->isTypeLegal(I.getType()))
          continue;

        Worklist.push_back(&I);
        Roots.insert(&I);
      }
    }
  // Early exit.
  if (Worklist.empty() || (TTI && !SeenExtFromIllegalType))
    return MinBWs;

  // Now proceed breadth-first, unioning values together.
  while (!Worklist.empty()) {
    Value *Val = Worklist.pop_back_val();
    Value *Leader = ECs.getOrInsertLeaderValue(Val);

    if (Visited.count(Val))
      continue;
    Visited.insert(Val);

    // Non-instructions terminate a chain successfully.
    if (!isa<Instruction>(Val))
      continue;
    Instruction *I = cast<Instruction>(Val);

    // If we encounter a type that is larger than 64 bits, we can't represent
    // it so bail out.
    if (DB.getDemandedBits(I).getBitWidth() > 64)
      return MapVector<Instruction *, uint64_t>();

    uint64_t V = DB.getDemandedBits(I).getZExtValue();
    DBits[Leader] |= V;
    DBits[I] = V;

    // Casts, loads and instructions outside of our range terminate a chain
    // successfully.
    if (isa<SExtInst>(I) || isa<ZExtInst>(I) || isa<LoadInst>(I) ||
        !InstructionSet.count(I))
      continue;

    // Unsafe casts terminate a chain unsuccessfully. We can't do anything
    // useful with bitcasts, ptrtoints or inttoptrs and it'd be unsafe to
    // transform anything that relies on them.
    if (isa<BitCastInst>(I) || isa<PtrToIntInst>(I) || isa<IntToPtrInst>(I) ||
        !I->getType()->isIntegerTy()) {
      DBits[Leader] |= ~0ULL;
      continue;
    }

    // We don't modify the types of PHIs. Reductions will already have been
    // truncated if possible, and inductions' sizes will have been chosen by
    // indvars.
    if (isa<PHINode>(I))
      continue;

    if (DBits[Leader] == ~0ULL)
      // All bits demanded, no point continuing.
      continue;

    for (Value *O : cast<User>(I)->operands()) {
      ECs.unionSets(Leader, O);
      Worklist.push_back(O);
    }
  }

  // Now we've discovered all values, walk them to see if there are
  // any users we didn't see. If there are, we can't optimize that
  // chain.
  for (auto &I : DBits)
    for (auto *U : I.first->users())
      if (U->getType()->isIntegerTy() && DBits.count(U) == 0)
        DBits[ECs.getOrInsertLeaderValue(I.first)] |= ~0ULL;

  for (auto I = ECs.begin(), E = ECs.end(); I != E; ++I) {
    uint64_t LeaderDemandedBits = 0;
    for (auto MI = ECs.member_begin(I), ME = ECs.member_end(); MI != ME; ++MI)
      LeaderDemandedBits |= DBits[*MI];

    uint64_t MinBW = (sizeof(LeaderDemandedBits) * 8) -
                     llvm::countLeadingZeros(LeaderDemandedBits);
    // Round up to a power of 2
    if (!isPowerOf2_64((uint64_t)MinBW))
      MinBW = NextPowerOf2(MinBW);

    // We don't modify the types of PHIs. Reductions will already have been
    // truncated if possible, and inductions' sizes will have been chosen by
    // indvars.
    // If we are required to shrink a PHI, abandon this entire equivalence class.
    bool Abort = false;
    for (auto MI = ECs.member_begin(I), ME = ECs.member_end(); MI != ME; ++MI)
      if (isa<PHINode>(*MI) && MinBW < (*MI)->getType()->getScalarSizeInBits()) {
        Abort = true;
        break;
      }
    if (Abort)
      continue;

    for (auto MI = ECs.member_begin(I), ME = ECs.member_end(); MI != ME; ++MI) {
      if (!isa<Instruction>(*MI))
        continue;
      Type *Ty = (*MI)->getType();
      if (Roots.count(*MI))
        Ty = cast<Instruction>(*MI)->getOperand(0)->getType();
      if (MinBW < Ty->getScalarSizeInBits())
        MinBWs[cast<Instruction>(*MI)] = MinBW;
    }
  }

  return MinBWs;
}
Exemplo n.º 3
0
bool AArch64A57FPLoadBalancing::runOnBasicBlock(MachineBasicBlock &MBB) {
  bool Changed = false;
  DEBUG(dbgs() << "Running on MBB: " << MBB << " - scanning instructions...\n");

  // First, scan the basic block producing a set of chains.

  // The currently "active" chains - chains that can be added to and haven't
  // been killed yet. This is keyed by register - all chains can only have one
  // "link" register between each inst in the chain.
  std::map<unsigned, Chain*> ActiveChains;
  std::set<Chain*> AllChains;
  unsigned Idx = 0;
  for (auto &MI : MBB)
    scanInstruction(&MI, Idx++, ActiveChains, AllChains);

  DEBUG(dbgs() << "Scan complete, "<< AllChains.size() << " chains created.\n");

  // Group the chains into disjoint sets based on their liveness range. This is
  // a poor-man's version of graph coloring. Ideally we'd create an interference
  // graph and perform full-on graph coloring on that, but;
  //   (a) That's rather heavyweight for only two colors.
  //   (b) We expect multiple disjoint interference regions - in practice the live
  //       range of chains is quite small and they are clustered between loads
  //       and stores.
  EquivalenceClasses<Chain*> EC;
  for (auto *I : AllChains)
    EC.insert(I);

  for (auto *I : AllChains) {
    for (auto *J : AllChains) {
      if (I != J && I->rangeOverlapsWith(J))
        EC.unionSets(I, J);
    }
  }
  DEBUG(dbgs() << "Created " << EC.getNumClasses() << " disjoint sets.\n");

  // Now we assume that every member of an equivalence class interferes
  // with every other member of that class, and with no members of other classes.

  // Convert the EquivalenceClasses to a simpler set of sets.
  std::vector<std::vector<Chain*> > V;
  for (auto I = EC.begin(), E = EC.end(); I != E; ++I) {
    std::vector<Chain*> Cs(EC.member_begin(I), EC.member_end());
    if (Cs.empty()) continue;
    V.push_back(Cs);
  }

  // Now we have a set of sets, order them by start address so
  // we can iterate over them sequentially.
  std::sort(V.begin(), V.end(),
            [](const std::vector<Chain*> &A,
               const std::vector<Chain*> &B) {
      return A.front()->startsBefore(B.front());
    });

  // As we only have two colors, we can track the global (BB-level) balance of
  // odds versus evens. We aim to keep this near zero to keep both execution
  // units fed.
  // Positive means we're even-heavy, negative we're odd-heavy.
  //
  // FIXME: If chains have interdependencies, for example:
  //   mul r0, r1, r2
  //   mul r3, r0, r1
  // We do not model this and may color each one differently, assuming we'll
  // get ILP when we obviously can't. This hasn't been seen to be a problem
  // in practice so far, so we simplify the algorithm by ignoring it.
  int Parity = 0;

  for (auto &I : V)
    Changed |= colorChainSet(I, MBB, Parity);

  for (auto *C : AllChains)
    delete C;

  return Changed;
}