vendor/clang/clang-release_39-r276489

1 files changed, 830 insertions, 0 deletions

diff --git a/lib/CodeGen/SwiftCallingConv.cpp b/lib/CodeGen/SwiftCallingConv.cpp
new file mode 100644
index 000000000000..6c20f8c9d3e9
--- /dev/null
+++ b/lib/CodeGen/SwiftCallingConv.cpp
@@ -0,0 +1,830 @@
+//===--- SwiftCallingConv.cpp - Lowering for the Swift calling convention -===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implementation of the abstract lowering for the Swift calling convention.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/CodeGen/SwiftCallingConv.h"
+#include "clang/Basic/TargetInfo.h"
+#include "CodeGenModule.h"
+#include "TargetInfo.h"
+
+using namespace clang;
+using namespace CodeGen;
+using namespace swiftcall;
+
+static const SwiftABIInfo &getSwiftABIInfo(CodeGenModule &CGM) {
+  return cast<SwiftABIInfo>(CGM.getTargetCodeGenInfo().getABIInfo());
+}
+
+static bool isPowerOf2(unsigned n) {
+  return n == (n & -n);
+}
+
+/// Given two types with the same size, try to find a common type.
+static llvm::Type *getCommonType(llvm::Type *first, llvm::Type *second) {
+  assert(first != second);
+
+  // Allow pointers to merge with integers, but prefer the integer type.
+  if (first->isIntegerTy()) {
+    if (second->isPointerTy()) return first;
+  } else if (first->isPointerTy()) {
+    if (second->isIntegerTy()) return second;
+    if (second->isPointerTy()) return first;
+
+  // Allow two vectors to be merged (given that they have the same size).
+  // This assumes that we never have two different vector register sets.
+  } else if (auto firstVecTy = dyn_cast<llvm::VectorType>(first)) {
+    if (auto secondVecTy = dyn_cast<llvm::VectorType>(second)) {
+      if (auto commonTy = getCommonType(firstVecTy->getElementType(),
+                                        secondVecTy->getElementType())) {
+        return (commonTy == firstVecTy->getElementType() ? first : second);
+      }
+    }
+  }
+
+  return nullptr;
+}
+
+static CharUnits getTypeStoreSize(CodeGenModule &CGM, llvm::Type *type) {
+  return CharUnits::fromQuantity(CGM.getDataLayout().getTypeStoreSize(type));
+}
+
+void SwiftAggLowering::addTypedData(QualType type, CharUnits begin) {
+  // Deal with various aggregate types as special cases:
+
+  // Record types.
+  if (auto recType = type->getAs<RecordType>()) {
+    addTypedData(recType->getDecl(), begin);
+
+  // Array types.
+  } else if (type->isArrayType()) {
+    // Incomplete array types (flexible array members?) don't provide
+    // data to lay out, and the other cases shouldn't be possible.
+    auto arrayType = CGM.getContext().getAsConstantArrayType(type);
+    if (!arrayType) return;
+
+    QualType eltType = arrayType->getElementType();
+    auto eltSize = CGM.getContext().getTypeSizeInChars(eltType);
+    for (uint64_t i = 0, e = arrayType->getSize().getZExtValue(); i != e; ++i) {
+      addTypedData(eltType, begin + i * eltSize);
+    }
+
+  // Complex types.
+  } else if (auto complexType = type->getAs<ComplexType>()) {
+    auto eltType = complexType->getElementType();
+    auto eltSize = CGM.getContext().getTypeSizeInChars(eltType);
+    auto eltLLVMType = CGM.getTypes().ConvertType(eltType);
+    addTypedData(eltLLVMType, begin, begin + eltSize);
+    addTypedData(eltLLVMType, begin + eltSize, begin + 2 * eltSize);
+
+  // Member pointer types.
+  } else if (type->getAs<MemberPointerType>()) {
+    // Just add it all as opaque.
+    addOpaqueData(begin, begin + CGM.getContext().getTypeSizeInChars(type));
+
+  // Everything else is scalar and should not convert as an LLVM aggregate.
+  } else {
+    // We intentionally convert as !ForMem because we want to preserve
+    // that a type was an i1.
+    auto llvmType = CGM.getTypes().ConvertType(type);
+    addTypedData(llvmType, begin);
+  }
+}
+
+void SwiftAggLowering::addTypedData(const RecordDecl *record, CharUnits begin) {
+  addTypedData(record, begin, CGM.getContext().getASTRecordLayout(record));
+}
+
+void SwiftAggLowering::addTypedData(const RecordDecl *record, CharUnits begin,
+                                    const ASTRecordLayout &layout) {
+  // Unions are a special case.
+  if (record->isUnion()) {
+    for (auto field : record->fields()) {
+      if (field->isBitField()) {
+        addBitFieldData(field, begin, 0);
+      } else {
+        addTypedData(field->getType(), begin);
+      }
+    }
+    return;
+  }
+
+  // Note that correctness does not rely on us adding things in
+  // their actual order of layout; it's just somewhat more efficient
+  // for the builder.
+
+  // With that in mind, add "early" C++ data.
+  auto cxxRecord = dyn_cast<CXXRecordDecl>(record);
+  if (cxxRecord) {
+    //   - a v-table pointer, if the class adds its own
+    if (layout.hasOwnVFPtr()) {
+      addTypedData(CGM.Int8PtrTy, begin);
+    }
+
+    //   - non-virtual bases
+    for (auto &baseSpecifier : cxxRecord->bases()) {
+      if (baseSpecifier.isVirtual()) continue;
+
+      auto baseRecord = baseSpecifier.getType()->getAsCXXRecordDecl();
+      addTypedData(baseRecord, begin + layout.getBaseClassOffset(baseRecord));
+    }
+
+    //   - a vbptr if the class adds its own
+    if (layout.hasOwnVBPtr()) {
+      addTypedData(CGM.Int8PtrTy, begin + layout.getVBPtrOffset());
+    }
+  }
+
+  // Add fields.
+  for (auto field : record->fields()) {
+    auto fieldOffsetInBits = layout.getFieldOffset(field->getFieldIndex());
+    if (field->isBitField()) {
+      addBitFieldData(field, begin, fieldOffsetInBits);
+    } else {
+      addTypedData(field->getType(),
+              begin + CGM.getContext().toCharUnitsFromBits(fieldOffsetInBits));
+    }
+  }
+
+  // Add "late" C++ data:
+  if (cxxRecord) {
+    //   - virtual bases
+    for (auto &vbaseSpecifier : cxxRecord->vbases()) {
+      auto baseRecord = vbaseSpecifier.getType()->getAsCXXRecordDecl();
+      addTypedData(baseRecord, begin + layout.getVBaseClassOffset(baseRecord));      
+    }
+  }
+}
+
+void SwiftAggLowering::addBitFieldData(const FieldDecl *bitfield,
+                                       CharUnits recordBegin,
+                                       uint64_t bitfieldBitBegin) {
+  assert(bitfield->isBitField());
+  auto &ctx = CGM.getContext();
+  auto width = bitfield->getBitWidthValue(ctx);
+
+  // We can ignore zero-width bit-fields.
+  if (width == 0) return;
+
+  // toCharUnitsFromBits rounds down.
+  CharUnits bitfieldByteBegin = ctx.toCharUnitsFromBits(bitfieldBitBegin);
+
+  // Find the offset of the last byte that is partially occupied by the
+  // bit-field; since we otherwise expect exclusive ends, the end is the
+  // next byte.
+  uint64_t bitfieldBitLast = bitfieldBitBegin + width - 1;
+  CharUnits bitfieldByteEnd =
+    ctx.toCharUnitsFromBits(bitfieldBitLast) + CharUnits::One();
+  addOpaqueData(recordBegin + bitfieldByteBegin,
+                recordBegin + bitfieldByteEnd);
+}
+
+void SwiftAggLowering::addTypedData(llvm::Type *type, CharUnits begin) {
+  assert(type && "didn't provide type for typed data");
+  addTypedData(type, begin, begin + getTypeStoreSize(CGM, type));
+}
+
+void SwiftAggLowering::addTypedData(llvm::Type *type,
+                                    CharUnits begin, CharUnits end) {
+  assert(type && "didn't provide type for typed data");
+  assert(getTypeStoreSize(CGM, type) == end - begin);
+
+  // Legalize vector types.
+  if (auto vecTy = dyn_cast<llvm::VectorType>(type)) {
+    SmallVector<llvm::Type*, 4> componentTys;
+    legalizeVectorType(CGM, end - begin, vecTy, componentTys);
+    assert(componentTys.size() >= 1);
+
+    // Walk the initial components.
+    for (size_t i = 0, e = componentTys.size(); i != e - 1; ++i) {
+      llvm::Type *componentTy = componentTys[i];
+      auto componentSize = getTypeStoreSize(CGM, componentTy);
+      assert(componentSize < end - begin);
+      addLegalTypedData(componentTy, begin, begin + componentSize);
+      begin += componentSize;
+    }
+
+    return addLegalTypedData(componentTys.back(), begin, end);
+  }
+
+  // Legalize integer types.
+  if (auto intTy = dyn_cast<llvm::IntegerType>(type)) {
+    if (!isLegalIntegerType(CGM, intTy))
+      return addOpaqueData(begin, end);
+  }
+
+  // All other types should be legal.
+  return addLegalTypedData(type, begin, end);
+}
+
+void SwiftAggLowering::addLegalTypedData(llvm::Type *type,
+                                         CharUnits begin, CharUnits end) {
+  // Require the type to be naturally aligned.
+  if (!begin.isZero() && !begin.isMultipleOf(getNaturalAlignment(CGM, type))) {
+
+    // Try splitting vector types.
+    if (auto vecTy = dyn_cast<llvm::VectorType>(type)) {
+      auto split = splitLegalVectorType(CGM, end - begin, vecTy);
+      auto eltTy = split.first;
+      auto numElts = split.second;
+
+      auto eltSize = (end - begin) / numElts;
+      assert(eltSize == getTypeStoreSize(CGM, eltTy));
+      for (size_t i = 0, e = numElts; i != e; ++i) {
+        addLegalTypedData(eltTy, begin, begin + eltSize);
+        begin += eltSize;
+      }
+      assert(begin == end);
+      return;
+    }
+
+    return addOpaqueData(begin, end);
+  }
+
+  addEntry(type, begin, end);
+}
+
+void SwiftAggLowering::addEntry(llvm::Type *type,
+                                CharUnits begin, CharUnits end) {
+  assert((!type ||
+          (!isa<llvm::StructType>(type) && !isa<llvm::ArrayType>(type))) &&
+         "cannot add aggregate-typed data");
+  assert(!type || begin.isMultipleOf(getNaturalAlignment(CGM, type)));
+
+  // Fast path: we can just add entries to the end.
+  if (Entries.empty() || Entries.back().End <= begin) {
+    Entries.push_back({begin, end, type});
+    return;
+  }
+
+  // Find the first existing entry that ends after the start of the new data.
+  // TODO: do a binary search if Entries is big enough for it to matter.
+  size_t index = Entries.size() - 1;
+  while (index != 0) {
+    if (Entries[index - 1].End <= begin) break;
+    --index;
+  }
+
+  // The entry ends after the start of the new data.
+  // If the entry starts after the end of the new data, there's no conflict.
+  if (Entries[index].Begin >= end) {
+    // This insertion is potentially O(n), but the way we generally build
+    // these layouts makes that unlikely to matter: we'd need a union of
+    // several very large types.
+    Entries.insert(Entries.begin() + index, {begin, end, type});
+    return;
+  }
+
+  // Otherwise, the ranges overlap.  The new range might also overlap
+  // with later ranges.
+restartAfterSplit:
+
+  // Simplest case: an exact overlap.
+  if (Entries[index].Begin == begin && Entries[index].End == end) {
+    // If the types match exactly, great.
+    if (Entries[index].Type == type) return;
+
+    // If either type is opaque, make the entry opaque and return.
+    if (Entries[index].Type == nullptr) {
+      return;
+    } else if (type == nullptr) {
+      Entries[index].Type = nullptr;
+      return;
+    }
+
+    // If they disagree in an ABI-agnostic way, just resolve the conflict
+    // arbitrarily.
+    if (auto entryType = getCommonType(Entries[index].Type, type)) {
+      Entries[index].Type = entryType;
+      return;
+    }
+
+    // Otherwise, make the entry opaque.
+    Entries[index].Type = nullptr;
+    return;
+  }
+
+  // Okay, we have an overlapping conflict of some sort.
+
+  // If we have a vector type, split it.
+  if (auto vecTy = dyn_cast_or_null<llvm::VectorType>(type)) {
+    auto eltTy = vecTy->getElementType();
+    CharUnits eltSize = (end - begin) / vecTy->getNumElements();
+    assert(eltSize == getTypeStoreSize(CGM, eltTy));
+    for (unsigned i = 0, e = vecTy->getNumElements(); i != e; ++i) {
+      addEntry(eltTy, begin, begin + eltSize);
+      begin += eltSize;
+    }
+    assert(begin == end);
+    return;
+  }
+
+  // If the entry is a vector type, split it and try again.
+  if (Entries[index].Type && Entries[index].Type->isVectorTy()) {
+    splitVectorEntry(index);
+    goto restartAfterSplit;
+  }
+
+  // Okay, we have no choice but to make the existing entry opaque.
+
+  Entries[index].Type = nullptr;
+
+  // Stretch the start of the entry to the beginning of the range.
+  if (begin < Entries[index].Begin) {
+    Entries[index].Begin = begin;
+    assert(index == 0 || begin >= Entries[index - 1].End);
+  }
+
+  // Stretch the end of the entry to the end of the range; but if we run
+  // into the start of the next entry, just leave the range there and repeat.
+  while (end > Entries[index].End) {
+    assert(Entries[index].Type == nullptr);
+
+    // If the range doesn't overlap the next entry, we're done.
+    if (index == Entries.size() - 1 || end <= Entries[index + 1].Begin) {
+      Entries[index].End = end;
+      break;
+    }
+
+    // Otherwise, stretch to the start of the next entry.
+    Entries[index].End = Entries[index + 1].Begin;
+
+    // Continue with the next entry.
+    index++;
+
+    // This entry needs to be made opaque if it is not already.
+    if (Entries[index].Type == nullptr)
+      continue;
+
+    // Split vector entries unless we completely subsume them.
+    if (Entries[index].Type->isVectorTy() &&
+        end < Entries[index].End) {
+      splitVectorEntry(index);
+    }
+
+    // Make the entry opaque.
+    Entries[index].Type = nullptr;
+  }
+}
+
+/// Replace the entry of vector type at offset 'index' with a sequence
+/// of its component vectors.
+void SwiftAggLowering::splitVectorEntry(unsigned index) {
+  auto vecTy = cast<llvm::VectorType>(Entries[index].Type);
+  auto split = splitLegalVectorType(CGM, Entries[index].getWidth(), vecTy);
+
+  auto eltTy = split.first;
+  CharUnits eltSize = getTypeStoreSize(CGM, eltTy);
+  auto numElts = split.second;
+  Entries.insert(&Entries[index + 1], numElts - 1, StorageEntry());
+
+  CharUnits begin = Entries[index].Begin;
+  for (unsigned i = 0; i != numElts; ++i) {
+    Entries[index].Type = eltTy;
+    Entries[index].Begin = begin;
+    Entries[index].End = begin + eltSize;
+    begin += eltSize;
+  }
+}
+
+/// Given a power-of-two unit size, return the offset of the aligned unit
+/// of that size which contains the given offset.
+///
+/// In other words, round down to the nearest multiple of the unit size.
+static CharUnits getOffsetAtStartOfUnit(CharUnits offset, CharUnits unitSize) {
+  assert(isPowerOf2(unitSize.getQuantity()));
+  auto unitMask = ~(unitSize.getQuantity() - 1);
+  return CharUnits::fromQuantity(offset.getQuantity() & unitMask);
+}
+
+static bool areBytesInSameUnit(CharUnits first, CharUnits second,
+                               CharUnits chunkSize) {
+  return getOffsetAtStartOfUnit(first, chunkSize)
+      == getOffsetAtStartOfUnit(second, chunkSize);
+}
+
+void SwiftAggLowering::finish() {
+  if (Entries.empty()) {
+    Finished = true;
+    return;
+  }
+
+  // We logically split the layout down into a series of chunks of this size,
+  // which is generally the size of a pointer.
+  const CharUnits chunkSize = getMaximumVoluntaryIntegerSize(CGM);
+
+  // First pass: if two entries share a chunk, make them both opaque
+  // and stretch one to meet the next.
+  bool hasOpaqueEntries = (Entries[0].Type == nullptr);
+  for (size_t i = 1, e = Entries.size(); i != e; ++i) {
+    if (areBytesInSameUnit(Entries[i - 1].End - CharUnits::One(),
+                           Entries[i].Begin, chunkSize)) {
+      Entries[i - 1].Type = nullptr;
+      Entries[i].Type = nullptr;
+      Entries[i - 1].End = Entries[i].Begin;
+      hasOpaqueEntries = true;
+
+    } else if (Entries[i].Type == nullptr) {
+      hasOpaqueEntries = true;
+    }
+  }
+
+  // The rest of the algorithm leaves non-opaque entries alone, so if we
+  // have no opaque entries, we're done.
+  if (!hasOpaqueEntries) {
+    Finished = true;
+    return;
+  }
+
+  // Okay, move the entries to a temporary and rebuild Entries.
+  auto orig = std::move(Entries);
+  assert(Entries.empty());
+
+  for (size_t i = 0, e = orig.size(); i != e; ++i) {
+    // Just copy over non-opaque entries.
+    if (orig[i].Type != nullptr) {
+      Entries.push_back(orig[i]);
+      continue;
+    }
+
+    // Scan forward to determine the full extent of the next opaque range.
+    // We know from the first pass that only contiguous ranges will overlap
+    // the same aligned chunk.
+    auto begin = orig[i].Begin;
+    auto end = orig[i].End;
+    while (i + 1 != e &&
+           orig[i + 1].Type == nullptr &&
+           end == orig[i + 1].Begin) {
+      end = orig[i + 1].End;
+      i++;
+    }
+
+    // Add an entry per intersected chunk.
+    do {
+      // Find the smallest aligned storage unit in the maximal aligned
+      // storage unit containing 'begin' that contains all the bytes in
+      // the intersection between the range and this chunk.
+      CharUnits localBegin = begin;
+      CharUnits chunkBegin = getOffsetAtStartOfUnit(localBegin, chunkSize);
+      CharUnits chunkEnd = chunkBegin + chunkSize;
+      CharUnits localEnd = std::min(end, chunkEnd);
+
+      // Just do a simple loop over ever-increasing unit sizes.
+      CharUnits unitSize = CharUnits::One();
+      CharUnits unitBegin, unitEnd;
+      for (; ; unitSize *= 2) {
+        assert(unitSize <= chunkSize);
+        unitBegin = getOffsetAtStartOfUnit(localBegin, unitSize);
+        unitEnd = unitBegin + unitSize;
+        if (unitEnd >= localEnd) break;
+      }
+
+      // Add an entry for this unit.
+      auto entryTy =
+        llvm::IntegerType::get(CGM.getLLVMContext(),
+                               CGM.getContext().toBits(unitSize));
+      Entries.push_back({unitBegin, unitEnd, entryTy});
+
+      // The next chunk starts where this chunk left off.
+      begin = localEnd;
+    } while (begin != end);
+  }
+
+  // Okay, finally finished.
+  Finished = true;
+}
+
+void SwiftAggLowering::enumerateComponents(EnumerationCallback callback) const {
+  assert(Finished && "haven't yet finished lowering");
+
+  for (auto &entry : Entries) {
+    callback(entry.Begin, entry.Type);
+  }
+}
+
+std::pair<llvm::StructType*, llvm::Type*>
+SwiftAggLowering::getCoerceAndExpandTypes() const {
+  assert(Finished && "haven't yet finished lowering");
+
+  auto &ctx = CGM.getLLVMContext();
+
+  if (Entries.empty()) {
+    auto type = llvm::StructType::get(ctx);
+    return { type, type };
+  }
+
+  SmallVector<llvm::Type*, 8> elts;
+  CharUnits lastEnd = CharUnits::Zero();
+  bool hasPadding = false;
+  bool packed = false;
+  for (auto &entry : Entries) {
+    if (entry.Begin != lastEnd) {
+      auto paddingSize = entry.Begin - lastEnd;
+      assert(!paddingSize.isNegative());
+
+      auto padding = llvm::ArrayType::get(llvm::Type::getInt8Ty(ctx),
+                                          paddingSize.getQuantity());
+      elts.push_back(padding);
+      hasPadding = true;
+    }
+
+    if (!packed && !entry.Begin.isMultipleOf(
+          CharUnits::fromQuantity(
+            CGM.getDataLayout().getABITypeAlignment(entry.Type))))
+      packed = true;
+
+    elts.push_back(entry.Type);
+    lastEnd = entry.End;
+  }
+
+  // We don't need to adjust 'packed' to deal with possible tail padding
+  // because we never do that kind of access through the coercion type.
+  auto coercionType = llvm::StructType::get(ctx, elts, packed);
+
+  llvm::Type *unpaddedType = coercionType;
+  if (hasPadding) {
+    elts.clear();
+    for (auto &entry : Entries) {
+      elts.push_back(entry.Type);
+    }
+    if (elts.size() == 1) {
+      unpaddedType = elts[0];
+    } else {
+      unpaddedType = llvm::StructType::get(ctx, elts, /*packed*/ false);
+    }
+  } else if (Entries.size() == 1) {
+    unpaddedType = Entries[0].Type;
+  }
+
+  return { coercionType, unpaddedType };
+}
+
+bool SwiftAggLowering::shouldPassIndirectly(bool asReturnValue) const {
+  assert(Finished && "haven't yet finished lowering");
+
+  // Empty types don't need to be passed indirectly.
+  if (Entries.empty()) return false;
+
+  CharUnits totalSize = Entries.back().End;
+
+  // Avoid copying the array of types when there's just a single element.
+  if (Entries.size() == 1) {
+    return getSwiftABIInfo(CGM).shouldPassIndirectlyForSwift(totalSize,
+                                                           Entries.back().Type,
+                                                             asReturnValue);    
+  }
+
+  SmallVector<llvm::Type*, 8> componentTys;
+  componentTys.reserve(Entries.size());
+  for (auto &entry : Entries) {
+    componentTys.push_back(entry.Type);
+  }
+  return getSwiftABIInfo(CGM).shouldPassIndirectlyForSwift(totalSize,
+                                                           componentTys,
+                                                           asReturnValue);
+}
+
+CharUnits swiftcall::getMaximumVoluntaryIntegerSize(CodeGenModule &CGM) {
+  // Currently always the size of an ordinary pointer.
+  return CGM.getContext().toCharUnitsFromBits(
+           CGM.getContext().getTargetInfo().getPointerWidth(0));
+}
+
+CharUnits swiftcall::getNaturalAlignment(CodeGenModule &CGM, llvm::Type *type) {
+  // For Swift's purposes, this is always just the store size of the type
+  // rounded up to a power of 2.
+  auto size = (unsigned long long) getTypeStoreSize(CGM, type).getQuantity();
+  if (!isPowerOf2(size)) {
+    size = 1ULL << (llvm::findLastSet(size, llvm::ZB_Undefined) + 1);
+  }
+  assert(size >= CGM.getDataLayout().getABITypeAlignment(type));
+  return CharUnits::fromQuantity(size);
+}
+
+bool swiftcall::isLegalIntegerType(CodeGenModule &CGM,
+                                   llvm::IntegerType *intTy) {
+  auto size = intTy->getBitWidth();
+  switch (size) {
+  case 1:
+  case 8:
+  case 16:
+  case 32:
+  case 64:
+    // Just assume that the above are always legal.
+    return true;
+
+  case 128:
+    return CGM.getContext().getTargetInfo().hasInt128Type();
+
+  default:
+    return false;
+  }
+}
+
+bool swiftcall::isLegalVectorType(CodeGenModule &CGM, CharUnits vectorSize,
+                                  llvm::VectorType *vectorTy) {
+  return isLegalVectorType(CGM, vectorSize, vectorTy->getElementType(),
+                           vectorTy->getNumElements());
+}
+
+bool swiftcall::isLegalVectorType(CodeGenModule &CGM, CharUnits vectorSize,
+                                  llvm::Type *eltTy, unsigned numElts) {
+  assert(numElts > 1 && "illegal vector length");
+  return getSwiftABIInfo(CGM)
+           .isLegalVectorTypeForSwift(vectorSize, eltTy, numElts);
+}
+
+std::pair<llvm::Type*, unsigned>
+swiftcall::splitLegalVectorType(CodeGenModule &CGM, CharUnits vectorSize,
+                                llvm::VectorType *vectorTy) {
+  auto numElts = vectorTy->getNumElements();
+  auto eltTy = vectorTy->getElementType();
+
+  // Try to split the vector type in half.
+  if (numElts >= 4 && isPowerOf2(numElts)) {
+    if (isLegalVectorType(CGM, vectorSize / 2, eltTy, numElts / 2))
+      return {llvm::VectorType::get(eltTy, numElts / 2), 2};
+  }
+
+  return {eltTy, numElts};
+}
+
+void swiftcall::legalizeVectorType(CodeGenModule &CGM, CharUnits origVectorSize,
+                                   llvm::VectorType *origVectorTy,
+                             llvm::SmallVectorImpl<llvm::Type*> &components) {
+  // If it's already a legal vector type, use it.
+  if (isLegalVectorType(CGM, origVectorSize, origVectorTy)) {
+    components.push_back(origVectorTy);
+    return;
+  }
+
+  // Try to split the vector into legal subvectors.
+  auto numElts = origVectorTy->getNumElements();
+  auto eltTy = origVectorTy->getElementType();
+  assert(numElts != 1);
+
+  // The largest size that we're still considering making subvectors of.
+  // Always a power of 2.
+  unsigned logCandidateNumElts = llvm::findLastSet(numElts, llvm::ZB_Undefined);
+  unsigned candidateNumElts = 1U << logCandidateNumElts;
+  assert(candidateNumElts <= numElts && candidateNumElts * 2 > numElts);
+
+  // Minor optimization: don't check the legality of this exact size twice.
+  if (candidateNumElts == numElts) {
+    logCandidateNumElts--;
+    candidateNumElts >>= 1;
+  }
+
+  CharUnits eltSize = (origVectorSize / numElts);
+  CharUnits candidateSize = eltSize * candidateNumElts;
+
+  // The sensibility of this algorithm relies on the fact that we never
+  // have a legal non-power-of-2 vector size without having the power of 2
+  // also be legal.
+  while (logCandidateNumElts > 0) {
+    assert(candidateNumElts == 1U << logCandidateNumElts);
+    assert(candidateNumElts <= numElts);
+    assert(candidateSize == eltSize * candidateNumElts);
+
+    // Skip illegal vector sizes.
+    if (!isLegalVectorType(CGM, candidateSize, eltTy, candidateNumElts)) {
+      logCandidateNumElts--;
+      candidateNumElts /= 2;
+      candidateSize /= 2;
+      continue;
+    }
+
+    // Add the right number of vectors of this size.
+    auto numVecs = numElts >> logCandidateNumElts;
+    components.append(numVecs, llvm::VectorType::get(eltTy, candidateNumElts));
+    numElts -= (numVecs << logCandidateNumElts);
+
+    if (numElts == 0) return;
+
+    // It's possible that the number of elements remaining will be legal.
+    // This can happen with e.g. <7 x float> when <3 x float> is legal.
+    // This only needs to be separately checked if it's not a power of 2.
+    if (numElts > 2 && !isPowerOf2(numElts) &&
+        isLegalVectorType(CGM, eltSize * numElts, eltTy, numElts)) {
+      components.push_back(llvm::VectorType::get(eltTy, numElts));
+      return;
+    }
+
+    // Bring vecSize down to something no larger than numElts.
+    do {
+      logCandidateNumElts--;
+      candidateNumElts /= 2;
+      candidateSize /= 2;
+    } while (candidateNumElts > numElts);
+  }
+
+  // Otherwise, just append a bunch of individual elements.
+  components.append(numElts, eltTy);
+}
+
+bool swiftcall::shouldPassCXXRecordIndirectly(CodeGenModule &CGM,
+                                              const CXXRecordDecl *record) {
+  // Following a recommendation from Richard Smith, pass a C++ type
+  // indirectly only if the destructor is non-trivial or *all* of the
+  // copy/move constructors are deleted or non-trivial.
+
+  if (record->hasNonTrivialDestructor())
+    return true;
+
+  // It would be nice if this were summarized on the CXXRecordDecl.
+  for (auto ctor : record->ctors()) {
+    if (ctor->isCopyOrMoveConstructor() && !ctor->isDeleted() &&
+        ctor->isTrivial()) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+static ABIArgInfo classifyExpandedType(SwiftAggLowering &lowering,
+                                       bool forReturn,
+                                       CharUnits alignmentForIndirect) {
+  if (lowering.empty()) {
+    return ABIArgInfo::getIgnore();
+  } else if (lowering.shouldPassIndirectly(forReturn)) {
+    return ABIArgInfo::getIndirect(alignmentForIndirect, /*byval*/ false);
+  } else {
+    auto types = lowering.getCoerceAndExpandTypes();
+    return ABIArgInfo::getCoerceAndExpand(types.first, types.second);
+  }
+}
+
+static ABIArgInfo classifyType(CodeGenModule &CGM, CanQualType type,
+                               bool forReturn) {
+  if (auto recordType = dyn_cast<RecordType>(type)) {
+    auto record = recordType->getDecl();
+    auto &layout = CGM.getContext().getASTRecordLayout(record);
+
+    if (auto cxxRecord = dyn_cast<CXXRecordDecl>(record)) {
+      if (shouldPassCXXRecordIndirectly(CGM, cxxRecord))
+        return ABIArgInfo::getIndirect(layout.getAlignment(), /*byval*/ false);
+    }
+
+    SwiftAggLowering lowering(CGM);
+    lowering.addTypedData(recordType->getDecl(), CharUnits::Zero(), layout);
+    lowering.finish();
+
+    return classifyExpandedType(lowering, forReturn, layout.getAlignment());
+  }
+
+  // Just assume that all of our target ABIs can support returning at least
+  // two integer or floating-point values.
+  if (isa<ComplexType>(type)) {
+    return (forReturn ? ABIArgInfo::getDirect() : ABIArgInfo::getExpand());
+  }
+
+  // Vector types may need to be legalized.
+  if (isa<VectorType>(type)) {
+    SwiftAggLowering lowering(CGM);
+    lowering.addTypedData(type, CharUnits::Zero());
+    lowering.finish();
+
+    CharUnits alignment = CGM.getContext().getTypeAlignInChars(type);
+    return classifyExpandedType(lowering, forReturn, alignment);
+  }
+
+  // Member pointer types need to be expanded, but it's a simple form of
+  // expansion that 'Direct' can handle.  Note that CanBeFlattened should be
+  // true for this to work.
+
+  // 'void' needs to be ignored.
+  if (type->isVoidType()) {
+    return ABIArgInfo::getIgnore();
+  }
+
+  // Everything else can be passed directly.
+  return ABIArgInfo::getDirect();
+}
+
+ABIArgInfo swiftcall::classifyReturnType(CodeGenModule &CGM, CanQualType type) {
+  return classifyType(CGM, type, /*forReturn*/ true);
+}
+
+ABIArgInfo swiftcall::classifyArgumentType(CodeGenModule &CGM,
+                                           CanQualType type) {
+  return classifyType(CGM, type, /*forReturn*/ false);
+}
+
+void swiftcall::computeABIInfo(CodeGenModule &CGM, CGFunctionInfo &FI) {
+  auto &retInfo = FI.getReturnInfo();
+  retInfo = classifyReturnType(CGM, FI.getReturnType());
+
+  for (unsigned i = 0, e = FI.arg_size(); i != e; ++i) {
+    auto &argInfo = FI.arg_begin()[i];
+    argInfo.info = classifyArgumentType(CGM, argInfo.type);
+  }
+}