C++ ApplySite::getArguments方法代码示例

/// Generate a new apply of a function_ref to replace an apply of a
/// witness_method when we've determined the actual function we'll end
/// up calling.
static ApplySite
devirtualizeWitnessMethod(ApplySite AI, SILFunction *F,
                          ProtocolConformanceRef C, OptRemark::Emitter *ORE) {
  // We know the witness thunk and the corresponding set of substitutions
  // required to invoke the protocol method at this point.
  auto &Module = AI.getModule();

  // Collect all the required substitutions.
  //
  // The complete set of substitutions may be different, e.g. because the found
  // witness thunk F may have been created by a specialization pass and have
  // additional generic parameters.
  auto SubMap = getWitnessMethodSubstitutions(Module, AI, F, C);

  // Figure out the exact bound type of the function to be called by
  // applying all substitutions.
  auto CalleeCanType = F->getLoweredFunctionType();
  auto SubstCalleeCanType = CalleeCanType->substGenericArgs(Module, SubMap);

  // Collect arguments from the apply instruction.
  auto Arguments = SmallVector<SILValue, 4>();

  // Iterate over the non self arguments and add them to the
  // new argument list, upcasting when required.
  SILBuilderWithScope B(AI.getInstruction());
  SILFunctionConventions substConv(SubstCalleeCanType, Module);
  unsigned substArgIdx = AI.getCalleeArgIndexOfFirstAppliedArg();
  for (auto arg : AI.getArguments()) {
    auto paramType = substConv.getSILArgumentType(substArgIdx++);
    if (arg->getType() != paramType)
      arg = castValueToABICompatibleType(&B, AI.getLoc(), arg,
                                         arg->getType(), paramType);
    Arguments.push_back(arg);
  }
  assert(substArgIdx == substConv.getNumSILArguments());

  // Replace old apply instruction by a new apply instruction that invokes
  // the witness thunk.
  SILBuilderWithScope Builder(AI.getInstruction());
  SILLocation Loc = AI.getLoc();
  FunctionRefInst *FRI = Builder.createFunctionRef(Loc, F);

  ApplySite SAI = replaceApplySite(Builder, Loc, AI, FRI, SubMap, Arguments,
                                   substConv);

  if (ORE)
    ORE->emit([&]() {
        using namespace OptRemark;
        return RemarkPassed("WitnessMethodDevirtualized", *AI.getInstruction())
               << "Devirtualized call to " << NV("Method", F);
      });
  NumWitnessDevirt++;
  return SAI;
}

/// Recursively check for conflicts with in-progress accesses at the given
/// apply.
///
/// Any captured variable accessed by a noescape closure is considered to be
/// accessed at the point that the closure is fully applied. This includes
/// variables captured by address by the noescape closure being applied or by
/// any other noescape closure that is itself passed as an argument to that
/// closure.
///
/// (1) Use AccessSummaryAnalysis to check each argument for statically
/// enforced accesses nested within the callee.
///
/// (2) If an applied argument is itself a function type, recursively check for
/// violations on the closure being passed as an argument.
///
/// (3) Walk up the chain of partial applies to recursively visit all arguments.
///
/// Note: This handles closures that are called immediately:
///  var i = 7
///  ({ (p: inout Int) in i = 8})(&i) // Overlapping access to 'i'
///
/// Note: This handles chains of partial applies:
///   pa1 = partial_apply f(c) : $(a, b, c)
///   pa2 = partial_apply pa1(b) : $(a, b)
///   apply pa2(a)
static void checkForViolationAtApply(ApplySite Apply, AccessState &State) {
  // First, check access to variables immediately captured at this apply site.
  checkCaptureAccess(Apply, State);

  // Next, recursively check any noescape closures passed as arguments at this
  // apply site.
  TinyPtrVector<PartialApplyInst *> partialApplies;
  for (SILValue Argument : Apply.getArguments()) {
    auto FnType = getSILFunctionTypeForValue(Argument);
    if (!FnType || !FnType->isNoEscape())
      continue;

    findClosuresForFunctionValue(Argument, partialApplies);
  }
  // Continue recursively walking up the chain of applies if necessary.
  findClosuresForFunctionValue(Apply.getCallee(), partialApplies);

  for (auto *PAI : partialApplies)
    checkForViolationAtApply(ApplySite(PAI), State);
}

/// Generate a new apply of a function_ref to replace an apply of a
/// witness_method when we've determined the actual function we'll end
/// up calling.
static ApplySite devirtualizeWitnessMethod(ApplySite AI, SILFunction *F,
                                           ProtocolConformanceRef C) {
  // We know the witness thunk and the corresponding set of substitutions
  // required to invoke the protocol method at this point.
  auto &Module = AI.getModule();

  // Collect all the required substitutions.
  //
  // The complete set of substitutions may be different, e.g. because the found
  // witness thunk F may have been created by a specialization pass and have
  // additional generic parameters.
  SmallVector<Substitution, 4> NewSubs;

  getWitnessMethodSubstitutions(AI, F, C, NewSubs);

  // Figure out the exact bound type of the function to be called by
  // applying all substitutions.
  auto CalleeCanType = F->getLoweredFunctionType();
  auto SubstCalleeCanType = CalleeCanType->substGenericArgs(Module, NewSubs);

  // Collect arguments from the apply instruction.
  auto Arguments = SmallVector<SILValue, 4>();

  // Iterate over the non self arguments and add them to the
  // new argument list, upcasting when required.
  SILBuilderWithScope B(AI.getInstruction());
  SILFunctionConventions substConv(SubstCalleeCanType, Module);
  unsigned substArgIdx = AI.getCalleeArgIndexOfFirstAppliedArg();
  for (auto arg : AI.getArguments()) {
    auto paramType = substConv.getSILArgumentType(substArgIdx++);
    if (arg->getType() != paramType)
      arg = castValueToABICompatibleType(&B, AI.getLoc(), arg,
                                         arg->getType(), paramType);
    Arguments.push_back(arg);
  }
  assert(substArgIdx == substConv.getNumSILArguments());

  // Replace old apply instruction by a new apply instruction that invokes
  // the witness thunk.
  SILBuilderWithScope Builder(AI.getInstruction());
  SILLocation Loc = AI.getLoc();
  FunctionRefInst *FRI = Builder.createFunctionRef(Loc, F);

  auto SubstCalleeSILType = SILType::getPrimitiveObjectType(SubstCalleeCanType);
  auto ResultSILType = substConv.getSILResultType();
  ApplySite SAI;

  if (auto *A = dyn_cast<ApplyInst>(AI))
    SAI = Builder.createApply(Loc, FRI, SubstCalleeSILType,
                              ResultSILType, NewSubs, Arguments,
                              A->isNonThrowing());
  if (auto *TAI = dyn_cast<TryApplyInst>(AI))
    SAI = Builder.createTryApply(Loc, FRI, SubstCalleeSILType,
                                 NewSubs, Arguments,
                                 TAI->getNormalBB(), TAI->getErrorBB());
  if (auto *PAI = dyn_cast<PartialApplyInst>(AI))
    SAI = Builder.createPartialApply(Loc, FRI, SubstCalleeSILType,
                                     NewSubs, Arguments, PAI->getType());

  NumWitnessDevirt++;
  return SAI;
}