VariOCL/ImplicitConditionalBarriers.cpp at master · JiadingGai/VariOCL · GitHub

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//#include "config.h"

#include "ImplicitConditionalBarriers.h"
#include "barrier_inst.h"
#include "barrier_utils.h"
//#include "BarrierBlock.h"
//#include "Workgroup.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"

#include <iostream>

namespace SpmdKernel {

using namespace llvm;

namespace Coarsening {

  char ImplicitConditionalBarriers::ID = 0;

  namespace {
    static
    RegisterPass<ImplicitConditionalBarriers>
      X("implicit-cond-barriers", "Adds implicit barriers to branches.");
  }

  void
  ImplicitConditionalBarriers::getAnalysisUsage(AnalysisUsage &AU) const
  {
    AU.addRequired<PostDominatorTree>();
    AU.addPreserved<PostDominatorTree>();
    AU.addRequired<DominatorTree>();
    AU.addPreserved<DominatorTree>();
  }

  BasicBlock*
  ImplicitConditionalBarriers::firstNonBackedgePredecessor(BasicBlock *bb)
  {
#if 0
    DominatorTree *DT = &getAnalysis<DominatorTree>();
    pred_iterator I = pred_begin(bb), E = pred_end(bb);

    if (I == E) {
      return NULL;
    }

    while (DT->dominates(bb, *I) && I != E) {
      ++I;
    }

    if (I == E) {
      return NULL;
    }
    else {
      return *I;
    }
#else
    DominatorTree *DT = &getAnalysis<DominatorTree>();
    BasicBlock *APred = NULL;
    std::vector<BasicBlock*> PredBlocks;
    for (pred_iterator I = pred_begin(bb), E = pred_end(bb); I != E; ++I) {
      BasicBlock *P = *I;
      PredBlocks.push_back(P);
    }

    for (std::vector<BasicBlock*>::iterator I = PredBlocks.begin(),
         E = PredBlocks.end(); I != E; ++I) {
      BasicBlock *PBlock = *I;

      if (!(DT->dominates(bb, PBlock))) {
        APred = PBlock;
        break;
      }
    }

    return APred;
#endif
  }

  bool
  ImplicitConditionalBarriers::runOnFunction(Function &F)
  {
    bool changed = false;

    //if (!Workgroup::isKernelToProcess(F))
    //  return false;

    BasicBlock *Fentry = &(F.getEntryBlock());
    PDT = &getAnalysis<PostDominatorTree>();

    typedef std::vector<BasicBlock*> BarrierBlockIndex;
    BarrierBlockIndex CondBarrierBBs;
    for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
      BasicBlock *BB = I;

      bool HasBarrier = BarrierInst::hasBarrier(BB);
      bool IsConditionalBarrier = !(PDT->dominates(BB, Fentry));

      if (HasBarrier && IsConditionalBarrier) {
        CondBarrierBBs.push_back(BB);
      }
    }

    for (BarrierBlockIndex::const_iterator i = CondBarrierBBs.begin(),
         e = CondBarrierBBs.end(); i != e; ++i) {
      BasicBlock *b = *i;
      BasicBlock *pos = b;

      BasicBlock *pred = firstNonBackedgePredecessor(b);

      // Locate the basic block that makes the barrier conditional.
      while (!containsJustABarrier(pred) && PDT->dominates(b, pred)) {
        pos = pred;
        pred = firstNonBackedgePredecessor(pred);

        if (pred == b)
          break;
      }

      if (containsJustABarrier(pos))
        continue;

      LLVMContext &LC = F.getContext();
      IntegerType * IntTy = IntegerType::get(LC, 32);
      Value *Args = ConstantInt::get(IntTy, 0);
      Instruction *CondAuxBarrierInst =
        BarrierInst::createBarrier(Args, pos->getFirstNonPHI());

      MDNode* CondAuxBarrierInfo =
        MDNode::get(LC, MDString::get(LC, "aux conditional barrier"));
      CondAuxBarrierInst->setMetadata("aux.cond.barrier", CondAuxBarrierInfo);

      changed = true;
    }

    return changed;
  }

}
}