示例#1
0
bool Loop::isAnnotatedParallel() const {
  MDNode *desiredLoopIdMetadata = getLoopID();

  if (!desiredLoopIdMetadata)
      return false;

  // The loop branch contains the parallel loop metadata. In order to ensure
  // that any parallel-loop-unaware optimization pass hasn't added loop-carried
  // dependencies (thus converted the loop back to a sequential loop), check
  // that all the memory instructions in the loop contain parallelism metadata
  // that point to the same unique "loop id metadata" the loop branch does.
  for (block_iterator BB = block_begin(), BE = block_end(); BB != BE; ++BB) {
    for (BasicBlock::iterator II = (*BB)->begin(), EE = (*BB)->end();
         II != EE; II++) {

      if (!II->mayReadOrWriteMemory())
        continue;

      // The memory instruction can refer to the loop identifier metadata
      // directly or indirectly through another list metadata (in case of
      // nested parallel loops). The loop identifier metadata refers to
      // itself so we can check both cases with the same routine.
      MDNode *loopIdMD =
          II->getMetadata(LLVMContext::MD_mem_parallel_loop_access);

      if (!loopIdMD)
        return false;

      bool loopIdMDFound = false;
      for (unsigned i = 0, e = loopIdMD->getNumOperands(); i < e; ++i) {
        if (loopIdMD->getOperand(i) == desiredLoopIdMetadata) {
          loopIdMDFound = true;
          break;
        }
      }

      if (!loopIdMDFound)
        return false;
    }
  }
  return true;
}
示例#2
0
Value *BoUpSLP::isUnsafeToSink(Instruction *Src, Instruction *Dst) {
  assert(Src->getParent() == Dst->getParent() && "Not the same BB");
  BasicBlock::iterator I = Src, E = Dst;
  /// Scan all of the instruction from SRC to DST and check if
  /// the source may alias.
  for (++I; I != E; ++I) {
    // Ignore store instructions that are marked as 'ignore'.
    if (MemBarrierIgnoreList.count(I)) continue;
    if (Src->mayWriteToMemory()) /* Write */ {
      if (!I->mayReadOrWriteMemory()) continue;
    } else /* Read */ {
      if (!I->mayWriteToMemory()) continue;
    }
    AliasAnalysis::Location A = getLocation(&*I);
    AliasAnalysis::Location B = getLocation(Src);

    if (!A.Ptr || !B.Ptr || AA->alias(A, B))
      return I;
  }
  return 0;
}