C++ RegionInfo类代码示例

  std::string getEdgeAttributes(RegionNode *srcNode,
                                GraphTraits<RegionInfo *>::ChildIteratorType CI,
                                ScopDetection *SD) {
    RegionNode *destNode = *CI;

    if (srcNode->isSubRegion() || destNode->isSubRegion())
      return "";

    // In case of a backedge, do not use it to define the layout of the nodes.
    BasicBlock *srcBB = srcNode->getNodeAs<BasicBlock>();
    BasicBlock *destBB = destNode->getNodeAs<BasicBlock>();

    RegionInfo *RI = SD->getRI();
    Region *R = RI->getRegionFor(destBB);

    while (R && R->getParent())
      if (R->getParent()->getEntry() == destBB)
        R = R->getParent();
      else
        break;

    if (R && R->getEntry() == destBB && R->contains(srcBB))
      return "constraint=false";

    return "";
  }

RegionInfo RegionInfoAnalysis::run(Function &F, FunctionAnalysisManager &AM) {
  RegionInfo RI;
  auto *DT = &AM.getResult<DominatorTreeAnalysis>(F);
  auto *PDT = &AM.getResult<PostDominatorTreeAnalysis>(F);
  auto *DF = &AM.getResult<DominanceFrontierAnalysis>(F);

  RI.recalculate(F, DT, PDT, DF);
  return RI;
}

/// \brief Analyze the predecessors of each block and build up predicates
void StructurizeCFG::gatherPredicates(RegionNode *N) {
  RegionInfo *RI = ParentRegion->getRegionInfo();
  BasicBlock *BB = N->getEntry();
  BBPredicates &Pred = Predicates[BB];
  BBPredicates &LPred = LoopPreds[BB];

  for (BasicBlock *P : predecessors(BB)) {
    // Ignore it if it's a branch from outside into our region entry
    if (!ParentRegion->contains(P))
      continue;

    Region *R = RI->getRegionFor(P);
    if (R == ParentRegion) {
      // It's a top level block in our region
      BranchInst *Term = cast<BranchInst>(P->getTerminator());
      for (unsigned i = 0, e = Term->getNumSuccessors(); i != e; ++i) {
        BasicBlock *Succ = Term->getSuccessor(i);
        if (Succ != BB)
          continue;

        if (Visited.count(P)) {
          // Normal forward edge
          if (Term->isConditional()) {
            // Try to treat it like an ELSE block
            BasicBlock *Other = Term->getSuccessor(!i);
            if (Visited.count(Other) && !Loops.count(Other) &&
                !Pred.count(Other) && !Pred.count(P)) {

              Pred[Other] = BoolFalse;
              Pred[P] = BoolTrue;
              continue;
            }
          }
          Pred[P] = buildCondition(Term, i, false);
        } else {
          // Back edge
          LPred[P] = buildCondition(Term, i, true);
        }
      }
    } else {
      // It's an exit from a sub region
      while (R->getParent() != ParentRegion)
        R = R->getParent();

      // Edge from inside a subregion to its entry, ignore it
      if (*R == *N)
        continue;

      BasicBlock *Entry = R->getEntry();
      if (Visited.count(Entry))
        Pred[Entry] = BoolTrue;
      else
        LPred[Entry] = BoolFalse;
    }
  }
}

  // Print the cluster of the subregions. This groups the single basic blocks
  // and adds a different background color for each group.
  static void printRegionCluster(const ScopDetection *SD, const Region *R,
                                 raw_ostream &O, unsigned depth = 0) {
    O.indent(2 * depth) << "subgraph cluster_" << static_cast<const void *>(R)
                        << " {\n";
    unsigned LineBegin, LineEnd;
    std::string FileName;

    getDebugLocation(R, LineBegin, LineEnd, FileName);

    std::string Location;
    if (LineBegin != (unsigned)-1) {
      Location = escapeString(FileName + ":" + std::to_string(LineBegin) + "-" +
                              std::to_string(LineEnd) + "\n");
    }

    std::string ErrorMessage = SD->regionIsInvalidBecause(R);
    ErrorMessage = escapeString(ErrorMessage);
    O.indent(2 * (depth + 1)) << "label = \"" << Location << ErrorMessage
                              << "\";\n";

    if (SD->isMaxRegionInScop(*R)) {
      O.indent(2 * (depth + 1)) << "style = filled;\n";

      // Set color to green.
      O.indent(2 * (depth + 1)) << "color = 3";
    } else {
      O.indent(2 * (depth + 1)) << "style = solid;\n";

      int color = (R->getDepth() * 2 % 12) + 1;

      // We do not want green again.
      if (color == 3)
        color = 6;

      O.indent(2 * (depth + 1)) << "color = " << color << "\n";
    }

    for (const auto &SubRegion : *R)
      printRegionCluster(SD, SubRegion.get(), O, depth + 1);

    RegionInfo *RI = R->getRegionInfo();

    for (const auto &BB : R->blocks())
      if (RI->getRegionFor(BB) == R)
        O.indent(2 * (depth + 1))
            << "Node"
            << static_cast<void *>(RI->getTopLevelRegion()->getBBNode(BB))
            << ";\n";

    O.indent(2 * depth) << "}\n";
  }

		void JSEdgeRemovalPass::padExitBlocks(RegionInfo& ri) {
			Region* top = ri.getTopLevelRegion();
			if(top != 0) {
				padExitBlocks(ri, top);
			}
		}

void TempScopInfo::buildCondition(BasicBlock *BB, Region &R) {
  BasicBlock *RegionEntry = R.getEntry();
  BBCond Cond;

  DomTreeNode *BBNode = DT->getNode(BB), *EntryNode = DT->getNode(RegionEntry);
  assert(BBNode && EntryNode && "Get null node while building condition!");

  // Walk up the dominance tree until reaching the entry node. Collect all
  // branching blocks on the path to BB except if BB postdominates the block
  // containing the condition.
  SmallVector<BasicBlock *, 4> DominatorBrBlocks;
  while (BBNode != EntryNode) {
    BasicBlock *CurBB = BBNode->getBlock();
    BBNode = BBNode->getIDom();
    assert(BBNode && "BBNode should not reach the root node!");

    if (PDT->dominates(CurBB, BBNode->getBlock()))
      continue;

    BranchInst *Br = dyn_cast<BranchInst>(BBNode->getBlock()->getTerminator());
    assert(Br && "A Valid Scop should only contain branch instruction");

    if (Br->isUnconditional())
      continue;

    DominatorBrBlocks.push_back(BBNode->getBlock());
  }

  RegionInfo *RI = R.getRegionInfo();
  // Iterate in reverse order over the dominating blocks.  Until a non-affine
  // branch was encountered add all conditions collected. If a non-affine branch
  // was encountered, stop as we overapproximate from here on anyway.
  for (auto BIt = DominatorBrBlocks.rbegin(), BEnd = DominatorBrBlocks.rend();
       BIt != BEnd; BIt++) {

    BasicBlock *BBNode = *BIt;
    BranchInst *Br = dyn_cast<BranchInst>(BBNode->getTerminator());
    assert(Br && "A Valid Scop should only contain branch instruction");
    assert(Br->isConditional() && "Assumed a conditional branch");

    if (SD->isNonAffineSubRegion(RI->getRegionFor(BBNode), &R))
      break;

    BasicBlock *TrueBB = Br->getSuccessor(0), *FalseBB = Br->getSuccessor(1);

    // Is BB on the ELSE side of the branch?
    bool inverted = DT->dominates(FalseBB, BB);

    // If both TrueBB and FalseBB dominate BB, one of them must be the target of
    // a back-edge, i.e. a loop header.
    if (inverted && DT->dominates(TrueBB, BB)) {
      assert(
          (DT->dominates(TrueBB, FalseBB) || DT->dominates(FalseBB, TrueBB)) &&
          "One of the successors should be the loop header and dominate the"
          "other!");

      // It is not an invert if the FalseBB is the header.
      if (DT->dominates(FalseBB, TrueBB))
        inverted = false;
    }

    Comparison *Cmp;
    buildAffineCondition(*(Br->getCondition()), inverted, &Cmp);
    Cond.push_back(*Cmp);
  }

  if (!Cond.empty())
    BBConds[BB] = Cond;
}

std::pair<polly::BBPair, BranchInst *>
polly::executeScopConditionally(Scop &S, Value *RTC, DominatorTree &DT,
                                RegionInfo &RI, LoopInfo &LI) {
  Region &R = S.getRegion();
  PollyIRBuilder Builder(S.getEntry());

  // Before:
  //
  //      \   /      //
  //    EnteringBB   //
  //   _____|_____   //
  //  /  EntryBB  \  //
  //  |  (region) |  //
  //  \_ExitingBB_/  //
  //        |        //
  //      ExitBB     //
  //      /    \     //

  // Create a fork block.
  BasicBlock *EnteringBB = S.getEnteringBlock();
  BasicBlock *EntryBB = S.getEntry();
  assert(EnteringBB && "Must be a simple region");
  BasicBlock *SplitBlock =
      splitEdge(EnteringBB, EntryBB, ".split_new_and_old", &DT, &LI, &RI);
  SplitBlock->setName("polly.split_new_and_old");

  // If EntryBB is the exit block of the region that includes Prev, exclude
  // SplitBlock from that region by making it itself the exit block. This is
  // trivially possible because there is just one edge to EnteringBB.
  // This is necessary because we will add an outgoing edge from SplitBlock,
  // which would violate the single exit block requirement of PrevRegion.
  Region *PrevRegion = RI.getRegionFor(EnteringBB);
  while (PrevRegion->getExit() == EntryBB) {
    PrevRegion->replaceExit(SplitBlock);
    PrevRegion = PrevRegion->getParent();
  }
  RI.setRegionFor(SplitBlock, PrevRegion);

  // Create a join block
  BasicBlock *ExitingBB = S.getExitingBlock();
  BasicBlock *ExitBB = S.getExit();
  assert(ExitingBB && "Must be a simple region");
  BasicBlock *MergeBlock =
      splitEdge(ExitingBB, ExitBB, ".merge_new_and_old", &DT, &LI, &RI);
  MergeBlock->setName("polly.merge_new_and_old");

  // Exclude the join block from the region.
  R.replaceExitRecursive(MergeBlock);
  RI.setRegionFor(MergeBlock, R.getParent());

  //      \   /      //
  //    EnteringBB   //
  //        |        //
  //    SplitBlock   //
  //   _____|_____   //
  //  /  EntryBB  \  //
  //  |  (region) |  //
  //  \_ExitingBB_/  //
  //        |        //
  //    MergeBlock   //
  //        |        //
  //      ExitBB     //
  //      /    \     //

  // Create the start and exiting block.
  Function *F = SplitBlock->getParent();
  BasicBlock *StartBlock =
      BasicBlock::Create(F->getContext(), "polly.start", F);
  BasicBlock *ExitingBlock =
      BasicBlock::Create(F->getContext(), "polly.exiting", F);
  SplitBlock->getTerminator()->eraseFromParent();
  Builder.SetInsertPoint(SplitBlock);
  BranchInst *CondBr = Builder.CreateCondBr(RTC, StartBlock, S.getEntry());

  if (Loop *L = LI.getLoopFor(SplitBlock)) {
    L->addBasicBlockToLoop(StartBlock, LI);
    L->addBasicBlockToLoop(ExitingBlock, LI);
  }
  DT.addNewBlock(StartBlock, SplitBlock);
  DT.addNewBlock(ExitingBlock, StartBlock);
  RI.setRegionFor(StartBlock, RI.getRegionFor(SplitBlock));
  RI.setRegionFor(ExitingBlock, RI.getRegionFor(SplitBlock));

  //      \   /                    //
  //    EnteringBB                 //
  //        |                      //
  //    SplitBlock---------\       //
  //   _____|_____         |       //
  //  /  EntryBB  \    StartBlock  //
  //  |  (region) |        |       //
  //  \_ExitingBB_/   ExitingBlock //
  //        |                      //
  //    MergeBlock                 //
  //        |                      //
  //      ExitBB                   //
  //      /    \                   //

  // Connect start block to exiting block.
  Builder.SetInsertPoint(StartBlock);
  Builder.CreateBr(ExitingBlock);
//.........这里部分代码省略.........