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llvm-project/clang/lib/CodeGen/SwiftCallingConv.cpp

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//===--- SwiftCallingConv.cpp - Lowering for the Swift calling convention -===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// 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));
}
static CharUnits getTypeAllocSize(CodeGenModule &CGM, llvm::Type *type) {
return CharUnits::fromQuantity(CGM.getDataLayout().getTypeAllocSize(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.begin() + 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);
}
static bool isMergeableEntryType(llvm::Type *type) {
// Opaquely-typed memory is always mergeable.
if (type == nullptr) return true;
// Pointers and integers are always mergeable. In theory we should not
// merge pointers, but (1) it doesn't currently matter in practice because
// the chunk size is never greater than the size of a pointer and (2)
// Swift IRGen uses integer types for a lot of things that are "really"
// just storing pointers (like Optional<SomePointer>). If we ever have a
// target that would otherwise combine pointers, we should put some effort
// into fixing those cases in Swift IRGen and then call out pointer types
// here.
// Floating-point and vector types should never be merged.
// Most such types are too large and highly-aligned to ever trigger merging
// in practice, but it's important for the rule to cover at least 'half'
// and 'float', as well as things like small vectors of 'i1' or 'i8'.
return (!type->isFloatingPointTy() && !type->isVectorTy());
}
bool SwiftAggLowering::shouldMergeEntries(const StorageEntry &first,
const StorageEntry &second,
CharUnits chunkSize) {
// Only merge entries that overlap the same chunk. We test this first
// despite being a bit more expensive because this is the condition that
// tends to prevent merging.
if (!areBytesInSameUnit(first.End - CharUnits::One(), second.Begin,
chunkSize))
return false;
return (isMergeableEntryType(first.Type) &&
isMergeableEntryType(second.Type));
}
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 should be merged, make them both opaque
// and stretch one to meet the next.
// Also, remember if there are any opaque entries.
bool hasOpaqueEntries = (Entries[0].Type == nullptr);
for (size_t i = 1, e = Entries.size(); i != e; ++i) {
if (shouldMergeEntries(Entries[i - 1], Entries[i], 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.End, 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.Begin + getTypeAllocSize(CGM, entry.Type);
assert(entry.End <= lastEnd);
}
// 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;
// Avoid copying the array of types when there's just a single element.
if (Entries.size() == 1) {
return getSwiftABIInfo(CGM).shouldPassIndirectlyForSwift(
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(componentTys,
asReturnValue);
}
bool swiftcall::shouldPassIndirectly(CodeGenModule &CGM,
ArrayRef<llvm::Type*> componentTys,
bool asReturnValue) {
return getSwiftABIInfo(CGM).shouldPassIndirectlyForSwift(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::mustPassRecordIndirectly(CodeGenModule &CGM,
const RecordDecl *record) {
// FIXME: should we not rely on the standard computation in Sema, just in
// case we want to diverge from the platform ABI (e.g. on targets where
// that uses the MSVC rule)?
return !record->canPassInRegisters();
}
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 (mustPassRecordIndirectly(CGM, record))
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);
}
}
// Is swifterror lowered to a register by the target ABI.
bool swiftcall::isSwiftErrorLoweredInRegister(CodeGenModule &CGM) {
return getSwiftABIInfo(CGM).isSwiftErrorInRegister();
}
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