C++ InlineCost::getCostDelta方法代码示例

bool PartialInlinerImpl::shouldPartialInline(
    CallSite CS, FunctionCloner &Cloner, BlockFrequency WeightedOutliningRcost,
    OptimizationRemarkEmitter &ORE) {

  using namespace ore;
  if (SkipCostAnalysis)
    return true;

  Instruction *Call = CS.getInstruction();
  Function *Callee = CS.getCalledFunction();
  assert(Callee == Cloner.ClonedFunc);

  Function *Caller = CS.getCaller();
  auto &CalleeTTI = (*GetTTI)(*Callee);
  InlineCost IC = getInlineCost(CS, getInlineParams(), CalleeTTI,
                                *GetAssumptionCache, GetBFI, PSI, &ORE);

  if (IC.isAlways()) {
    ORE.emit(OptimizationRemarkAnalysis(DEBUG_TYPE, "AlwaysInline", Call)
             << NV("Callee", Cloner.OrigFunc)
             << " should always be fully inlined, not partially");
    return false;
  }

  if (IC.isNever()) {
    ORE.emit(OptimizationRemarkMissed(DEBUG_TYPE, "NeverInline", Call)
             << NV("Callee", Cloner.OrigFunc) << " not partially inlined into "
             << NV("Caller", Caller)
             << " because it should never be inlined (cost=never)");
    return false;
  }

  if (!IC) {
    ORE.emit(OptimizationRemarkAnalysis(DEBUG_TYPE, "TooCostly", Call)
             << NV("Callee", Cloner.OrigFunc) << " not partially inlined into "
             << NV("Caller", Caller) << " because too costly to inline (cost="
             << NV("Cost", IC.getCost()) << ", threshold="
             << NV("Threshold", IC.getCostDelta() + IC.getCost()) << ")");
    return false;
  }
  const DataLayout &DL = Caller->getParent()->getDataLayout();

  // The savings of eliminating the call:
  int NonWeightedSavings = getCallsiteCost(CS, DL);
  BlockFrequency NormWeightedSavings(NonWeightedSavings);

  // Weighted saving is smaller than weighted cost, return false
  if (NormWeightedSavings < WeightedOutliningRcost) {
    ORE.emit(
        OptimizationRemarkAnalysis(DEBUG_TYPE, "OutliningCallcostTooHigh", Call)
        << NV("Callee", Cloner.OrigFunc) << " not partially inlined into "
        << NV("Caller", Caller) << " runtime overhead (overhead="
        << NV("Overhead", (unsigned)WeightedOutliningRcost.getFrequency())
        << ", savings="
        << NV("Savings", (unsigned)NormWeightedSavings.getFrequency()) << ")"
        << " of making the outlined call is too high");

    return false;
  }

  ORE.emit(OptimizationRemarkAnalysis(DEBUG_TYPE, "CanBePartiallyInlined", Call)
           << NV("Callee", Cloner.OrigFunc) << " can be partially inlined into "
           << NV("Caller", Caller) << " with cost=" << NV("Cost", IC.getCost())
           << " (threshold="
           << NV("Threshold", IC.getCostDelta() + IC.getCost()) << ")");
  return true;
}

/// Return true if the inliner should attempt to inline at the given CallSite.
bool Inliner::shouldInline(CallSite CS) {
  InlineCost IC = getInlineCost(CS);
  
  if (IC.isAlways()) {
    DEBUG(dbgs() << "    Inlining: cost=always"
          << ", Call: " << *CS.getInstruction() << "\n");
    emitAnalysis(CS, Twine(CS.getCalledFunction()->getName()) +
                         " should always be inlined (cost=always)");
    return true;
  }
  
  if (IC.isNever()) {
    DEBUG(dbgs() << "    NOT Inlining: cost=never"
          << ", Call: " << *CS.getInstruction() << "\n");
    emitAnalysis(CS, Twine(CS.getCalledFunction()->getName() +
                           " should never be inlined (cost=never)"));
    return false;
  }
  
  Function *Caller = CS.getCaller();
  if (!IC) {
    DEBUG(dbgs() << "    NOT Inlining: cost=" << IC.getCost()
          << ", thres=" << (IC.getCostDelta() + IC.getCost())
          << ", Call: " << *CS.getInstruction() << "\n");
    emitAnalysis(CS, Twine(CS.getCalledFunction()->getName() +
                           " too costly to inline (cost=") +
                         Twine(IC.getCost()) + ", threshold=" +
                         Twine(IC.getCostDelta() + IC.getCost()) + ")");
    return false;
  }
  
  // Try to detect the case where the current inlining candidate caller (call
  // it B) is a static or linkonce-ODR function and is an inlining candidate
  // elsewhere, and the current candidate callee (call it C) is large enough
  // that inlining it into B would make B too big to inline later. In these
  // circumstances it may be best not to inline C into B, but to inline B into
  // its callers.
  //
  // This only applies to static and linkonce-ODR functions because those are
  // expected to be available for inlining in the translation units where they
  // are used. Thus we will always have the opportunity to make local inlining
  // decisions. Importantly the linkonce-ODR linkage covers inline functions
  // and templates in C++.
  //
  // FIXME: All of this logic should be sunk into getInlineCost. It relies on
  // the internal implementation of the inline cost metrics rather than
  // treating them as truly abstract units etc.
  if (Caller->hasLocalLinkage() || Caller->hasLinkOnceODRLinkage()) {
    int TotalSecondaryCost = 0;
    // The candidate cost to be imposed upon the current function.
    int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1);
    // This bool tracks what happens if we do NOT inline C into B.
    bool callerWillBeRemoved = Caller->hasLocalLinkage();
    // This bool tracks what happens if we DO inline C into B.
    bool inliningPreventsSomeOuterInline = false;
    for (User *U : Caller->users()) {
      CallSite CS2(U);

      // If this isn't a call to Caller (it could be some other sort
      // of reference) skip it.  Such references will prevent the caller
      // from being removed.
      if (!CS2 || CS2.getCalledFunction() != Caller) {
        callerWillBeRemoved = false;
        continue;
      }

      InlineCost IC2 = getInlineCost(CS2);
      ++NumCallerCallersAnalyzed;
      if (!IC2) {
        callerWillBeRemoved = false;
        continue;
      }
      if (IC2.isAlways())
        continue;

      // See if inlining or original callsite would erase the cost delta of
      // this callsite. We subtract off the penalty for the call instruction,
      // which we would be deleting.
      if (IC2.getCostDelta() <= CandidateCost) {
        inliningPreventsSomeOuterInline = true;
        TotalSecondaryCost += IC2.getCost();
      }
    }
    // If all outer calls to Caller would get inlined, the cost for the last
    // one is set very low by getInlineCost, in anticipation that Caller will
    // be removed entirely.  We did not account for this above unless there
    // is only one caller of Caller.
    if (callerWillBeRemoved && !Caller->use_empty())
      TotalSecondaryCost += InlineConstants::LastCallToStaticBonus;

    if (inliningPreventsSomeOuterInline && TotalSecondaryCost < IC.getCost()) {
      DEBUG(dbgs() << "    NOT Inlining: " << *CS.getInstruction() <<
           " Cost = " << IC.getCost() <<
           ", outer Cost = " << TotalSecondaryCost << '\n');
      emitAnalysis(
          CS, Twine("Not inlining. Cost of inlining " +
                    CS.getCalledFunction()->getName() +
                    " increases the cost of inlining " +
                    CS.getCaller()->getName() + " in other contexts"));
//.........这里部分代码省略.........

/// Return true if the inliner should attempt to inline at the given CallSite.
static bool shouldInline(CallSite CS,
                         function_ref<InlineCost(CallSite CS)> GetInlineCost,
                         OptimizationRemarkEmitter &ORE) {
  using namespace ore;
  InlineCost IC = GetInlineCost(CS);
  Instruction *Call = CS.getInstruction();
  Function *Callee = CS.getCalledFunction();

  if (IC.isAlways()) {
    DEBUG(dbgs() << "    Inlining: cost=always"
                 << ", Call: " << *CS.getInstruction() << "\n");
    ORE.emit(OptimizationRemarkAnalysis(DEBUG_TYPE, "AlwaysInline", Call)
             << NV("Callee", Callee)
             << " should always be inlined (cost=always)");
    return true;
  }

  if (IC.isNever()) {
    DEBUG(dbgs() << "    NOT Inlining: cost=never"
                 << ", Call: " << *CS.getInstruction() << "\n");
    ORE.emit(OptimizationRemarkAnalysis(DEBUG_TYPE, "NeverInline", Call)
             << NV("Callee", Callee)
             << " should never be inlined (cost=never)");
    return false;
  }

  Function *Caller = CS.getCaller();
  if (!IC) {
    DEBUG(dbgs() << "    NOT Inlining: cost=" << IC.getCost()
                 << ", thres=" << (IC.getCostDelta() + IC.getCost())
                 << ", Call: " << *CS.getInstruction() << "\n");
    ORE.emit(OptimizationRemarkAnalysis(DEBUG_TYPE, "TooCostly", Call)
             << NV("Callee", Callee) << " too costly to inline (cost="
             << NV("Cost", IC.getCost()) << ", threshold="
             << NV("Threshold", IC.getCostDelta() + IC.getCost()) << ")");
    return false;
  }

  int TotalSecondaryCost = 0;
  if (shouldBeDeferred(Caller, CS, IC, TotalSecondaryCost, GetInlineCost)) {
    DEBUG(dbgs() << "    NOT Inlining: " << *CS.getInstruction()
                 << " Cost = " << IC.getCost()
                 << ", outer Cost = " << TotalSecondaryCost << '\n');
    ORE.emit(OptimizationRemarkAnalysis(DEBUG_TYPE,
                                        "IncreaseCostInOtherContexts", Call)
             << "Not inlining. Cost of inlining " << NV("Callee", Callee)
             << " increases the cost of inlining " << NV("Caller", Caller)
             << " in other contexts");
    return false;
  }

  DEBUG(dbgs() << "    Inlining: cost=" << IC.getCost()
               << ", thres=" << (IC.getCostDelta() + IC.getCost())
               << ", Call: " << *CS.getInstruction() << '\n');
  ORE.emit(OptimizationRemarkAnalysis(DEBUG_TYPE, "CanBeInlined", Call)
           << NV("Callee", Callee) << " can be inlined into "
           << NV("Caller", Caller) << " with cost=" << NV("Cost", IC.getCost())
           << " (threshold="
           << NV("Threshold", IC.getCostDelta() + IC.getCost()) << ")");
  return true;
}