C++ SILGenFunction::emitManagedLoadCopy方法代码示例

/// Specialized emitter for Builtin.reinterpretCast.
static ManagedValue emitBuiltinReinterpretCast(SILGenFunction &SGF,
                                         SILLocation loc,
                                         SubstitutionMap substitutions,
                                         ArrayRef<ManagedValue> args,
                                         SGFContext C) {
  assert(args.size() == 1 && "reinterpretCast should be given one argument");
  assert(substitutions.getReplacementTypes().size() == 2 &&
         "reinterpretCast should have two subs");
  
  auto &fromTL = SGF.getTypeLowering(substitutions.getReplacementTypes()[0]);
  auto &toTL = SGF.getTypeLowering(substitutions.getReplacementTypes()[1]);
  
  // If casting between address types, cast the address.
  if (fromTL.isAddress() || toTL.isAddress()) {
    SILValue fromAddr;

    // If the from value is not an address, move it to a buffer.
    if (!fromTL.isAddress()) {
      fromAddr = SGF.emitTemporaryAllocation(loc, args[0].getValue()->getType());
      fromTL.emitStore(SGF.B, loc, args[0].getValue(), fromAddr,
                       StoreOwnershipQualifier::Init);
    } else {
      fromAddr = args[0].getValue();
    }
    auto toAddr = SGF.B.createUncheckedAddrCast(loc, fromAddr,
                                      toTL.getLoweredType().getAddressType());
    
    // Load and retain the destination value if it's loadable. Leave the cleanup
    // on the original value since we don't know anything about it's type.
    if (!toTL.isAddress()) {
      return SGF.emitManagedLoadCopy(loc, toAddr, toTL);
    }
    // Leave the cleanup on the original value.
    if (toTL.isTrivial())
      return ManagedValue::forUnmanaged(toAddr);

    // Initialize the +1 result buffer without taking the incoming value. The
    // source and destination cleanups will be independent.
    return SGF.B.bufferForExpr(
        loc, toTL.getLoweredType(), toTL, C,
        [&](SILValue bufferAddr) {
          SGF.B.createCopyAddr(loc, toAddr, bufferAddr, IsNotTake,
                               IsInitialization);
        });
  }
  // Create the appropriate bitcast based on the source and dest types.
  ManagedValue in = args[0];
  SILType resultTy = toTL.getLoweredType();
  if (resultTy.isTrivial(SGF.F))
    return SGF.B.createUncheckedTrivialBitCast(loc, in, resultTy);

  // If we can perform a ref cast, just return.
  if (auto refCast = SGF.B.tryCreateUncheckedRefCast(loc, in, resultTy))
    return refCast;

  // Otherwise leave the original cleanup and retain the cast value.
  SILValue out = SGF.B.createUncheckedBitwiseCast(loc, in.getValue(), resultTy);
  return SGF.emitManagedRetain(loc, out, toTL);
}

/// Specialized emitter for Builtin.reinterpretCast.
static ManagedValue emitBuiltinReinterpretCast(SILGenFunction &gen,
                                         SILLocation loc,
                                         SubstitutionList substitutions,
                                         ArrayRef<ManagedValue> args,
                                         CanFunctionType formalApplyType,
                                         SGFContext C) {
  assert(args.size() == 1 && "reinterpretCast should be given one argument");
  assert(substitutions.size() == 2 && "reinterpretCast should have two subs");
  
  auto &fromTL = gen.getTypeLowering(substitutions[0].getReplacement());
  auto &toTL = gen.getTypeLowering(substitutions[1].getReplacement());
  
  // If casting between address-only types, cast the address.
  if (!fromTL.isLoadable() || !toTL.isLoadable()) {
    SILValue fromAddr;

    // If the from value is loadable, move it to a buffer.
    if (fromTL.isLoadable()) {
      fromAddr = gen.emitTemporaryAllocation(loc, args[0].getValue()->getType());
      fromTL.emitStore(gen.B, loc, args[0].getValue(), fromAddr,
                       StoreOwnershipQualifier::Init);
    } else {
      fromAddr = args[0].getValue();
    }
    auto toAddr = gen.B.createUncheckedAddrCast(loc, fromAddr,
                                      toTL.getLoweredType().getAddressType());
    
    // Load and retain the destination value if it's loadable. Leave the cleanup
    // on the original value since we don't know anything about it's type.
    if (toTL.isLoadable()) {
      return gen.emitManagedLoadCopy(loc, toAddr, toTL);
    }
    // Leave the cleanup on the original value.
    if (toTL.isTrivial())
      return ManagedValue::forUnmanaged(toAddr);

    // Initialize the +1 result buffer without taking the incoming value. The
    // source and destination cleanups will be independent.
    return gen.B.bufferForExpr(
        loc, toTL.getLoweredType(), toTL, C,
        [&](SILValue bufferAddr) {
          gen.B.createCopyAddr(loc, toAddr, bufferAddr, IsNotTake,
                               IsInitialization);
        });
  }
  // Create the appropriate bitcast based on the source and dest types.
  auto &in = args[0];
  SILValue out = gen.B.createUncheckedBitCast(loc, in.getValue(),
                                              toTL.getLoweredType());

  // If the cast reduces to unchecked_ref_cast, then the source and dest
  // have identical cleanup, so just forward the cleanup as an optimization.
  if (isa<UncheckedRefCastInst>(out))
    return ManagedValue(out, in.getCleanup());

  // Otherwise leave the original cleanup and retain the cast value.
  return gen.emitManagedRetain(loc, out, toTL);
}