1 //===--- SwiftCallingConv.cpp - Lowering for the Swift calling convention -===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // Implementation of the abstract lowering for the Swift calling convention.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "clang/CodeGen/SwiftCallingConv.h"
14 #include "clang/Basic/TargetInfo.h"
15 #include "CodeGenModule.h"
16 #include "TargetInfo.h"
17
18 using namespace clang;
19 using namespace CodeGen;
20 using namespace swiftcall;
21
getSwiftABIInfo(CodeGenModule & CGM)22 static const SwiftABIInfo &getSwiftABIInfo(CodeGenModule &CGM) {
23 return cast<SwiftABIInfo>(CGM.getTargetCodeGenInfo().getABIInfo());
24 }
25
isPowerOf2(unsigned n)26 static bool isPowerOf2(unsigned n) {
27 return n == (n & -n);
28 }
29
30 /// Given two types with the same size, try to find a common type.
getCommonType(llvm::Type * first,llvm::Type * second)31 static llvm::Type *getCommonType(llvm::Type *first, llvm::Type *second) {
32 assert(first != second);
33
34 // Allow pointers to merge with integers, but prefer the integer type.
35 if (first->isIntegerTy()) {
36 if (second->isPointerTy()) return first;
37 } else if (first->isPointerTy()) {
38 if (second->isIntegerTy()) return second;
39 if (second->isPointerTy()) return first;
40
41 // Allow two vectors to be merged (given that they have the same size).
42 // This assumes that we never have two different vector register sets.
43 } else if (auto firstVecTy = dyn_cast<llvm::VectorType>(first)) {
44 if (auto secondVecTy = dyn_cast<llvm::VectorType>(second)) {
45 if (auto commonTy = getCommonType(firstVecTy->getElementType(),
46 secondVecTy->getElementType())) {
47 return (commonTy == firstVecTy->getElementType() ? first : second);
48 }
49 }
50 }
51
52 return nullptr;
53 }
54
getTypeStoreSize(CodeGenModule & CGM,llvm::Type * type)55 static CharUnits getTypeStoreSize(CodeGenModule &CGM, llvm::Type *type) {
56 return CharUnits::fromQuantity(CGM.getDataLayout().getTypeStoreSize(type));
57 }
58
getTypeAllocSize(CodeGenModule & CGM,llvm::Type * type)59 static CharUnits getTypeAllocSize(CodeGenModule &CGM, llvm::Type *type) {
60 return CharUnits::fromQuantity(CGM.getDataLayout().getTypeAllocSize(type));
61 }
62
addTypedData(QualType type,CharUnits begin)63 void SwiftAggLowering::addTypedData(QualType type, CharUnits begin) {
64 // Deal with various aggregate types as special cases:
65
66 // Record types.
67 if (auto recType = type->getAs<RecordType>()) {
68 addTypedData(recType->getDecl(), begin);
69
70 // Array types.
71 } else if (type->isArrayType()) {
72 // Incomplete array types (flexible array members?) don't provide
73 // data to lay out, and the other cases shouldn't be possible.
74 auto arrayType = CGM.getContext().getAsConstantArrayType(type);
75 if (!arrayType) return;
76
77 QualType eltType = arrayType->getElementType();
78 auto eltSize = CGM.getContext().getTypeSizeInChars(eltType);
79 for (uint64_t i = 0, e = arrayType->getSize().getZExtValue(); i != e; ++i) {
80 addTypedData(eltType, begin + i * eltSize);
81 }
82
83 // Complex types.
84 } else if (auto complexType = type->getAs<ComplexType>()) {
85 auto eltType = complexType->getElementType();
86 auto eltSize = CGM.getContext().getTypeSizeInChars(eltType);
87 auto eltLLVMType = CGM.getTypes().ConvertType(eltType);
88 addTypedData(eltLLVMType, begin, begin + eltSize);
89 addTypedData(eltLLVMType, begin + eltSize, begin + 2 * eltSize);
90
91 // Member pointer types.
92 } else if (type->getAs<MemberPointerType>()) {
93 // Just add it all as opaque.
94 addOpaqueData(begin, begin + CGM.getContext().getTypeSizeInChars(type));
95
96 // Everything else is scalar and should not convert as an LLVM aggregate.
97 } else {
98 // We intentionally convert as !ForMem because we want to preserve
99 // that a type was an i1.
100 auto llvmType = CGM.getTypes().ConvertType(type);
101 addTypedData(llvmType, begin);
102 }
103 }
104
addTypedData(const RecordDecl * record,CharUnits begin)105 void SwiftAggLowering::addTypedData(const RecordDecl *record, CharUnits begin) {
106 addTypedData(record, begin, CGM.getContext().getASTRecordLayout(record));
107 }
108
addTypedData(const RecordDecl * record,CharUnits begin,const ASTRecordLayout & layout)109 void SwiftAggLowering::addTypedData(const RecordDecl *record, CharUnits begin,
110 const ASTRecordLayout &layout) {
111 // Unions are a special case.
112 if (record->isUnion()) {
113 for (auto field : record->fields()) {
114 if (field->isBitField()) {
115 addBitFieldData(field, begin, 0);
116 } else {
117 addTypedData(field->getType(), begin);
118 }
119 }
120 return;
121 }
122
123 // Note that correctness does not rely on us adding things in
124 // their actual order of layout; it's just somewhat more efficient
125 // for the builder.
126
127 // With that in mind, add "early" C++ data.
128 auto cxxRecord = dyn_cast<CXXRecordDecl>(record);
129 if (cxxRecord) {
130 // - a v-table pointer, if the class adds its own
131 if (layout.hasOwnVFPtr()) {
132 addTypedData(CGM.Int8PtrTy, begin);
133 }
134
135 // - non-virtual bases
136 for (auto &baseSpecifier : cxxRecord->bases()) {
137 if (baseSpecifier.isVirtual()) continue;
138
139 auto baseRecord = baseSpecifier.getType()->getAsCXXRecordDecl();
140 addTypedData(baseRecord, begin + layout.getBaseClassOffset(baseRecord));
141 }
142
143 // - a vbptr if the class adds its own
144 if (layout.hasOwnVBPtr()) {
145 addTypedData(CGM.Int8PtrTy, begin + layout.getVBPtrOffset());
146 }
147 }
148
149 // Add fields.
150 for (auto field : record->fields()) {
151 auto fieldOffsetInBits = layout.getFieldOffset(field->getFieldIndex());
152 if (field->isBitField()) {
153 addBitFieldData(field, begin, fieldOffsetInBits);
154 } else {
155 addTypedData(field->getType(),
156 begin + CGM.getContext().toCharUnitsFromBits(fieldOffsetInBits));
157 }
158 }
159
160 // Add "late" C++ data:
161 if (cxxRecord) {
162 // - virtual bases
163 for (auto &vbaseSpecifier : cxxRecord->vbases()) {
164 auto baseRecord = vbaseSpecifier.getType()->getAsCXXRecordDecl();
165 addTypedData(baseRecord, begin + layout.getVBaseClassOffset(baseRecord));
166 }
167 }
168 }
169
addBitFieldData(const FieldDecl * bitfield,CharUnits recordBegin,uint64_t bitfieldBitBegin)170 void SwiftAggLowering::addBitFieldData(const FieldDecl *bitfield,
171 CharUnits recordBegin,
172 uint64_t bitfieldBitBegin) {
173 assert(bitfield->isBitField());
174 auto &ctx = CGM.getContext();
175 auto width = bitfield->getBitWidthValue(ctx);
176
177 // We can ignore zero-width bit-fields.
178 if (width == 0) return;
179
180 // toCharUnitsFromBits rounds down.
181 CharUnits bitfieldByteBegin = ctx.toCharUnitsFromBits(bitfieldBitBegin);
182
183 // Find the offset of the last byte that is partially occupied by the
184 // bit-field; since we otherwise expect exclusive ends, the end is the
185 // next byte.
186 uint64_t bitfieldBitLast = bitfieldBitBegin + width - 1;
187 CharUnits bitfieldByteEnd =
188 ctx.toCharUnitsFromBits(bitfieldBitLast) + CharUnits::One();
189 addOpaqueData(recordBegin + bitfieldByteBegin,
190 recordBegin + bitfieldByteEnd);
191 }
192
addTypedData(llvm::Type * type,CharUnits begin)193 void SwiftAggLowering::addTypedData(llvm::Type *type, CharUnits begin) {
194 assert(type && "didn't provide type for typed data");
195 addTypedData(type, begin, begin + getTypeStoreSize(CGM, type));
196 }
197
addTypedData(llvm::Type * type,CharUnits begin,CharUnits end)198 void SwiftAggLowering::addTypedData(llvm::Type *type,
199 CharUnits begin, CharUnits end) {
200 assert(type && "didn't provide type for typed data");
201 assert(getTypeStoreSize(CGM, type) == end - begin);
202
203 // Legalize vector types.
204 if (auto vecTy = dyn_cast<llvm::VectorType>(type)) {
205 SmallVector<llvm::Type*, 4> componentTys;
206 legalizeVectorType(CGM, end - begin, vecTy, componentTys);
207 assert(componentTys.size() >= 1);
208
209 // Walk the initial components.
210 for (size_t i = 0, e = componentTys.size(); i != e - 1; ++i) {
211 llvm::Type *componentTy = componentTys[i];
212 auto componentSize = getTypeStoreSize(CGM, componentTy);
213 assert(componentSize < end - begin);
214 addLegalTypedData(componentTy, begin, begin + componentSize);
215 begin += componentSize;
216 }
217
218 return addLegalTypedData(componentTys.back(), begin, end);
219 }
220
221 // Legalize integer types.
222 if (auto intTy = dyn_cast<llvm::IntegerType>(type)) {
223 if (!isLegalIntegerType(CGM, intTy))
224 return addOpaqueData(begin, end);
225 }
226
227 // All other types should be legal.
228 return addLegalTypedData(type, begin, end);
229 }
230
addLegalTypedData(llvm::Type * type,CharUnits begin,CharUnits end)231 void SwiftAggLowering::addLegalTypedData(llvm::Type *type,
232 CharUnits begin, CharUnits end) {
233 // Require the type to be naturally aligned.
234 if (!begin.isZero() && !begin.isMultipleOf(getNaturalAlignment(CGM, type))) {
235
236 // Try splitting vector types.
237 if (auto vecTy = dyn_cast<llvm::VectorType>(type)) {
238 auto split = splitLegalVectorType(CGM, end - begin, vecTy);
239 auto eltTy = split.first;
240 auto numElts = split.second;
241
242 auto eltSize = (end - begin) / numElts;
243 assert(eltSize == getTypeStoreSize(CGM, eltTy));
244 for (size_t i = 0, e = numElts; i != e; ++i) {
245 addLegalTypedData(eltTy, begin, begin + eltSize);
246 begin += eltSize;
247 }
248 assert(begin == end);
249 return;
250 }
251
252 return addOpaqueData(begin, end);
253 }
254
255 addEntry(type, begin, end);
256 }
257
addEntry(llvm::Type * type,CharUnits begin,CharUnits end)258 void SwiftAggLowering::addEntry(llvm::Type *type,
259 CharUnits begin, CharUnits end) {
260 assert((!type ||
261 (!isa<llvm::StructType>(type) && !isa<llvm::ArrayType>(type))) &&
262 "cannot add aggregate-typed data");
263 assert(!type || begin.isMultipleOf(getNaturalAlignment(CGM, type)));
264
265 // Fast path: we can just add entries to the end.
266 if (Entries.empty() || Entries.back().End <= begin) {
267 Entries.push_back({begin, end, type});
268 return;
269 }
270
271 // Find the first existing entry that ends after the start of the new data.
272 // TODO: do a binary search if Entries is big enough for it to matter.
273 size_t index = Entries.size() - 1;
274 while (index != 0) {
275 if (Entries[index - 1].End <= begin) break;
276 --index;
277 }
278
279 // The entry ends after the start of the new data.
280 // If the entry starts after the end of the new data, there's no conflict.
281 if (Entries[index].Begin >= end) {
282 // This insertion is potentially O(n), but the way we generally build
283 // these layouts makes that unlikely to matter: we'd need a union of
284 // several very large types.
285 Entries.insert(Entries.begin() + index, {begin, end, type});
286 return;
287 }
288
289 // Otherwise, the ranges overlap. The new range might also overlap
290 // with later ranges.
291 restartAfterSplit:
292
293 // Simplest case: an exact overlap.
294 if (Entries[index].Begin == begin && Entries[index].End == end) {
295 // If the types match exactly, great.
296 if (Entries[index].Type == type) return;
297
298 // If either type is opaque, make the entry opaque and return.
299 if (Entries[index].Type == nullptr) {
300 return;
301 } else if (type == nullptr) {
302 Entries[index].Type = nullptr;
303 return;
304 }
305
306 // If they disagree in an ABI-agnostic way, just resolve the conflict
307 // arbitrarily.
308 if (auto entryType = getCommonType(Entries[index].Type, type)) {
309 Entries[index].Type = entryType;
310 return;
311 }
312
313 // Otherwise, make the entry opaque.
314 Entries[index].Type = nullptr;
315 return;
316 }
317
318 // Okay, we have an overlapping conflict of some sort.
319
320 // If we have a vector type, split it.
321 if (auto vecTy = dyn_cast_or_null<llvm::VectorType>(type)) {
322 auto eltTy = vecTy->getElementType();
323 CharUnits eltSize = (end - begin) / vecTy->getNumElements();
324 assert(eltSize == getTypeStoreSize(CGM, eltTy));
325 for (unsigned i = 0, e = vecTy->getNumElements(); i != e; ++i) {
326 addEntry(eltTy, begin, begin + eltSize);
327 begin += eltSize;
328 }
329 assert(begin == end);
330 return;
331 }
332
333 // If the entry is a vector type, split it and try again.
334 if (Entries[index].Type && Entries[index].Type->isVectorTy()) {
335 splitVectorEntry(index);
336 goto restartAfterSplit;
337 }
338
339 // Okay, we have no choice but to make the existing entry opaque.
340
341 Entries[index].Type = nullptr;
342
343 // Stretch the start of the entry to the beginning of the range.
344 if (begin < Entries[index].Begin) {
345 Entries[index].Begin = begin;
346 assert(index == 0 || begin >= Entries[index - 1].End);
347 }
348
349 // Stretch the end of the entry to the end of the range; but if we run
350 // into the start of the next entry, just leave the range there and repeat.
351 while (end > Entries[index].End) {
352 assert(Entries[index].Type == nullptr);
353
354 // If the range doesn't overlap the next entry, we're done.
355 if (index == Entries.size() - 1 || end <= Entries[index + 1].Begin) {
356 Entries[index].End = end;
357 break;
358 }
359
360 // Otherwise, stretch to the start of the next entry.
361 Entries[index].End = Entries[index + 1].Begin;
362
363 // Continue with the next entry.
364 index++;
365
366 // This entry needs to be made opaque if it is not already.
367 if (Entries[index].Type == nullptr)
368 continue;
369
370 // Split vector entries unless we completely subsume them.
371 if (Entries[index].Type->isVectorTy() &&
372 end < Entries[index].End) {
373 splitVectorEntry(index);
374 }
375
376 // Make the entry opaque.
377 Entries[index].Type = nullptr;
378 }
379 }
380
381 /// Replace the entry of vector type at offset 'index' with a sequence
382 /// of its component vectors.
splitVectorEntry(unsigned index)383 void SwiftAggLowering::splitVectorEntry(unsigned index) {
384 auto vecTy = cast<llvm::VectorType>(Entries[index].Type);
385 auto split = splitLegalVectorType(CGM, Entries[index].getWidth(), vecTy);
386
387 auto eltTy = split.first;
388 CharUnits eltSize = getTypeStoreSize(CGM, eltTy);
389 auto numElts = split.second;
390 Entries.insert(Entries.begin() + index + 1, numElts - 1, StorageEntry());
391
392 CharUnits begin = Entries[index].Begin;
393 for (unsigned i = 0; i != numElts; ++i) {
394 Entries[index].Type = eltTy;
395 Entries[index].Begin = begin;
396 Entries[index].End = begin + eltSize;
397 begin += eltSize;
398 }
399 }
400
401 /// Given a power-of-two unit size, return the offset of the aligned unit
402 /// of that size which contains the given offset.
403 ///
404 /// In other words, round down to the nearest multiple of the unit size.
getOffsetAtStartOfUnit(CharUnits offset,CharUnits unitSize)405 static CharUnits getOffsetAtStartOfUnit(CharUnits offset, CharUnits unitSize) {
406 assert(isPowerOf2(unitSize.getQuantity()));
407 auto unitMask = ~(unitSize.getQuantity() - 1);
408 return CharUnits::fromQuantity(offset.getQuantity() & unitMask);
409 }
410
areBytesInSameUnit(CharUnits first,CharUnits second,CharUnits chunkSize)411 static bool areBytesInSameUnit(CharUnits first, CharUnits second,
412 CharUnits chunkSize) {
413 return getOffsetAtStartOfUnit(first, chunkSize)
414 == getOffsetAtStartOfUnit(second, chunkSize);
415 }
416
isMergeableEntryType(llvm::Type * type)417 static bool isMergeableEntryType(llvm::Type *type) {
418 // Opaquely-typed memory is always mergeable.
419 if (type == nullptr) return true;
420
421 // Pointers and integers are always mergeable. In theory we should not
422 // merge pointers, but (1) it doesn't currently matter in practice because
423 // the chunk size is never greater than the size of a pointer and (2)
424 // Swift IRGen uses integer types for a lot of things that are "really"
425 // just storing pointers (like Optional<SomePointer>). If we ever have a
426 // target that would otherwise combine pointers, we should put some effort
427 // into fixing those cases in Swift IRGen and then call out pointer types
428 // here.
429
430 // Floating-point and vector types should never be merged.
431 // Most such types are too large and highly-aligned to ever trigger merging
432 // in practice, but it's important for the rule to cover at least 'half'
433 // and 'float', as well as things like small vectors of 'i1' or 'i8'.
434 return (!type->isFloatingPointTy() && !type->isVectorTy());
435 }
436
shouldMergeEntries(const StorageEntry & first,const StorageEntry & second,CharUnits chunkSize)437 bool SwiftAggLowering::shouldMergeEntries(const StorageEntry &first,
438 const StorageEntry &second,
439 CharUnits chunkSize) {
440 // Only merge entries that overlap the same chunk. We test this first
441 // despite being a bit more expensive because this is the condition that
442 // tends to prevent merging.
443 if (!areBytesInSameUnit(first.End - CharUnits::One(), second.Begin,
444 chunkSize))
445 return false;
446
447 return (isMergeableEntryType(first.Type) &&
448 isMergeableEntryType(second.Type));
449 }
450
finish()451 void SwiftAggLowering::finish() {
452 if (Entries.empty()) {
453 Finished = true;
454 return;
455 }
456
457 // We logically split the layout down into a series of chunks of this size,
458 // which is generally the size of a pointer.
459 const CharUnits chunkSize = getMaximumVoluntaryIntegerSize(CGM);
460
461 // First pass: if two entries should be merged, make them both opaque
462 // and stretch one to meet the next.
463 // Also, remember if there are any opaque entries.
464 bool hasOpaqueEntries = (Entries[0].Type == nullptr);
465 for (size_t i = 1, e = Entries.size(); i != e; ++i) {
466 if (shouldMergeEntries(Entries[i - 1], Entries[i], chunkSize)) {
467 Entries[i - 1].Type = nullptr;
468 Entries[i].Type = nullptr;
469 Entries[i - 1].End = Entries[i].Begin;
470 hasOpaqueEntries = true;
471
472 } else if (Entries[i].Type == nullptr) {
473 hasOpaqueEntries = true;
474 }
475 }
476
477 // The rest of the algorithm leaves non-opaque entries alone, so if we
478 // have no opaque entries, we're done.
479 if (!hasOpaqueEntries) {
480 Finished = true;
481 return;
482 }
483
484 // Okay, move the entries to a temporary and rebuild Entries.
485 auto orig = std::move(Entries);
486 assert(Entries.empty());
487
488 for (size_t i = 0, e = orig.size(); i != e; ++i) {
489 // Just copy over non-opaque entries.
490 if (orig[i].Type != nullptr) {
491 Entries.push_back(orig[i]);
492 continue;
493 }
494
495 // Scan forward to determine the full extent of the next opaque range.
496 // We know from the first pass that only contiguous ranges will overlap
497 // the same aligned chunk.
498 auto begin = orig[i].Begin;
499 auto end = orig[i].End;
500 while (i + 1 != e &&
501 orig[i + 1].Type == nullptr &&
502 end == orig[i + 1].Begin) {
503 end = orig[i + 1].End;
504 i++;
505 }
506
507 // Add an entry per intersected chunk.
508 do {
509 // Find the smallest aligned storage unit in the maximal aligned
510 // storage unit containing 'begin' that contains all the bytes in
511 // the intersection between the range and this chunk.
512 CharUnits localBegin = begin;
513 CharUnits chunkBegin = getOffsetAtStartOfUnit(localBegin, chunkSize);
514 CharUnits chunkEnd = chunkBegin + chunkSize;
515 CharUnits localEnd = std::min(end, chunkEnd);
516
517 // Just do a simple loop over ever-increasing unit sizes.
518 CharUnits unitSize = CharUnits::One();
519 CharUnits unitBegin, unitEnd;
520 for (; ; unitSize *= 2) {
521 assert(unitSize <= chunkSize);
522 unitBegin = getOffsetAtStartOfUnit(localBegin, unitSize);
523 unitEnd = unitBegin + unitSize;
524 if (unitEnd >= localEnd) break;
525 }
526
527 // Add an entry for this unit.
528 auto entryTy =
529 llvm::IntegerType::get(CGM.getLLVMContext(),
530 CGM.getContext().toBits(unitSize));
531 Entries.push_back({unitBegin, unitEnd, entryTy});
532
533 // The next chunk starts where this chunk left off.
534 begin = localEnd;
535 } while (begin != end);
536 }
537
538 // Okay, finally finished.
539 Finished = true;
540 }
541
enumerateComponents(EnumerationCallback callback) const542 void SwiftAggLowering::enumerateComponents(EnumerationCallback callback) const {
543 assert(Finished && "haven't yet finished lowering");
544
545 for (auto &entry : Entries) {
546 callback(entry.Begin, entry.End, entry.Type);
547 }
548 }
549
550 std::pair<llvm::StructType*, llvm::Type*>
getCoerceAndExpandTypes() const551 SwiftAggLowering::getCoerceAndExpandTypes() const {
552 assert(Finished && "haven't yet finished lowering");
553
554 auto &ctx = CGM.getLLVMContext();
555
556 if (Entries.empty()) {
557 auto type = llvm::StructType::get(ctx);
558 return { type, type };
559 }
560
561 SmallVector<llvm::Type*, 8> elts;
562 CharUnits lastEnd = CharUnits::Zero();
563 bool hasPadding = false;
564 bool packed = false;
565 for (auto &entry : Entries) {
566 if (entry.Begin != lastEnd) {
567 auto paddingSize = entry.Begin - lastEnd;
568 assert(!paddingSize.isNegative());
569
570 auto padding = llvm::ArrayType::get(llvm::Type::getInt8Ty(ctx),
571 paddingSize.getQuantity());
572 elts.push_back(padding);
573 hasPadding = true;
574 }
575
576 if (!packed && !entry.Begin.isMultipleOf(
577 CharUnits::fromQuantity(
578 CGM.getDataLayout().getABITypeAlignment(entry.Type))))
579 packed = true;
580
581 elts.push_back(entry.Type);
582
583 lastEnd = entry.Begin + getTypeAllocSize(CGM, entry.Type);
584 assert(entry.End <= lastEnd);
585 }
586
587 // We don't need to adjust 'packed' to deal with possible tail padding
588 // because we never do that kind of access through the coercion type.
589 auto coercionType = llvm::StructType::get(ctx, elts, packed);
590
591 llvm::Type *unpaddedType = coercionType;
592 if (hasPadding) {
593 elts.clear();
594 for (auto &entry : Entries) {
595 elts.push_back(entry.Type);
596 }
597 if (elts.size() == 1) {
598 unpaddedType = elts[0];
599 } else {
600 unpaddedType = llvm::StructType::get(ctx, elts, /*packed*/ false);
601 }
602 } else if (Entries.size() == 1) {
603 unpaddedType = Entries[0].Type;
604 }
605
606 return { coercionType, unpaddedType };
607 }
608
shouldPassIndirectly(bool asReturnValue) const609 bool SwiftAggLowering::shouldPassIndirectly(bool asReturnValue) const {
610 assert(Finished && "haven't yet finished lowering");
611
612 // Empty types don't need to be passed indirectly.
613 if (Entries.empty()) return false;
614
615 // Avoid copying the array of types when there's just a single element.
616 if (Entries.size() == 1) {
617 return getSwiftABIInfo(CGM).shouldPassIndirectlyForSwift(
618 Entries.back().Type,
619 asReturnValue);
620 }
621
622 SmallVector<llvm::Type*, 8> componentTys;
623 componentTys.reserve(Entries.size());
624 for (auto &entry : Entries) {
625 componentTys.push_back(entry.Type);
626 }
627 return getSwiftABIInfo(CGM).shouldPassIndirectlyForSwift(componentTys,
628 asReturnValue);
629 }
630
shouldPassIndirectly(CodeGenModule & CGM,ArrayRef<llvm::Type * > componentTys,bool asReturnValue)631 bool swiftcall::shouldPassIndirectly(CodeGenModule &CGM,
632 ArrayRef<llvm::Type*> componentTys,
633 bool asReturnValue) {
634 return getSwiftABIInfo(CGM).shouldPassIndirectlyForSwift(componentTys,
635 asReturnValue);
636 }
637
getMaximumVoluntaryIntegerSize(CodeGenModule & CGM)638 CharUnits swiftcall::getMaximumVoluntaryIntegerSize(CodeGenModule &CGM) {
639 // Currently always the size of an ordinary pointer.
640 return CGM.getContext().toCharUnitsFromBits(
641 CGM.getContext().getTargetInfo().getPointerWidth(0));
642 }
643
getNaturalAlignment(CodeGenModule & CGM,llvm::Type * type)644 CharUnits swiftcall::getNaturalAlignment(CodeGenModule &CGM, llvm::Type *type) {
645 // For Swift's purposes, this is always just the store size of the type
646 // rounded up to a power of 2.
647 auto size = (unsigned long long) getTypeStoreSize(CGM, type).getQuantity();
648 if (!isPowerOf2(size)) {
649 size = 1ULL << (llvm::findLastSet(size, llvm::ZB_Undefined) + 1);
650 }
651 assert(size >= CGM.getDataLayout().getABITypeAlignment(type));
652 return CharUnits::fromQuantity(size);
653 }
654
isLegalIntegerType(CodeGenModule & CGM,llvm::IntegerType * intTy)655 bool swiftcall::isLegalIntegerType(CodeGenModule &CGM,
656 llvm::IntegerType *intTy) {
657 auto size = intTy->getBitWidth();
658 switch (size) {
659 case 1:
660 case 8:
661 case 16:
662 case 32:
663 case 64:
664 // Just assume that the above are always legal.
665 return true;
666
667 case 128:
668 return CGM.getContext().getTargetInfo().hasInt128Type();
669
670 default:
671 return false;
672 }
673 }
674
isLegalVectorType(CodeGenModule & CGM,CharUnits vectorSize,llvm::VectorType * vectorTy)675 bool swiftcall::isLegalVectorType(CodeGenModule &CGM, CharUnits vectorSize,
676 llvm::VectorType *vectorTy) {
677 return isLegalVectorType(CGM, vectorSize, vectorTy->getElementType(),
678 vectorTy->getNumElements());
679 }
680
isLegalVectorType(CodeGenModule & CGM,CharUnits vectorSize,llvm::Type * eltTy,unsigned numElts)681 bool swiftcall::isLegalVectorType(CodeGenModule &CGM, CharUnits vectorSize,
682 llvm::Type *eltTy, unsigned numElts) {
683 assert(numElts > 1 && "illegal vector length");
684 return getSwiftABIInfo(CGM)
685 .isLegalVectorTypeForSwift(vectorSize, eltTy, numElts);
686 }
687
688 std::pair<llvm::Type*, unsigned>
splitLegalVectorType(CodeGenModule & CGM,CharUnits vectorSize,llvm::VectorType * vectorTy)689 swiftcall::splitLegalVectorType(CodeGenModule &CGM, CharUnits vectorSize,
690 llvm::VectorType *vectorTy) {
691 auto numElts = vectorTy->getNumElements();
692 auto eltTy = vectorTy->getElementType();
693
694 // Try to split the vector type in half.
695 if (numElts >= 4 && isPowerOf2(numElts)) {
696 if (isLegalVectorType(CGM, vectorSize / 2, eltTy, numElts / 2))
697 return {llvm::FixedVectorType::get(eltTy, numElts / 2), 2};
698 }
699
700 return {eltTy, numElts};
701 }
702
legalizeVectorType(CodeGenModule & CGM,CharUnits origVectorSize,llvm::VectorType * origVectorTy,llvm::SmallVectorImpl<llvm::Type * > & components)703 void swiftcall::legalizeVectorType(CodeGenModule &CGM, CharUnits origVectorSize,
704 llvm::VectorType *origVectorTy,
705 llvm::SmallVectorImpl<llvm::Type*> &components) {
706 // If it's already a legal vector type, use it.
707 if (isLegalVectorType(CGM, origVectorSize, origVectorTy)) {
708 components.push_back(origVectorTy);
709 return;
710 }
711
712 // Try to split the vector into legal subvectors.
713 auto numElts = origVectorTy->getNumElements();
714 auto eltTy = origVectorTy->getElementType();
715 assert(numElts != 1);
716
717 // The largest size that we're still considering making subvectors of.
718 // Always a power of 2.
719 unsigned logCandidateNumElts = llvm::findLastSet(numElts, llvm::ZB_Undefined);
720 unsigned candidateNumElts = 1U << logCandidateNumElts;
721 assert(candidateNumElts <= numElts && candidateNumElts * 2 > numElts);
722
723 // Minor optimization: don't check the legality of this exact size twice.
724 if (candidateNumElts == numElts) {
725 logCandidateNumElts--;
726 candidateNumElts >>= 1;
727 }
728
729 CharUnits eltSize = (origVectorSize / numElts);
730 CharUnits candidateSize = eltSize * candidateNumElts;
731
732 // The sensibility of this algorithm relies on the fact that we never
733 // have a legal non-power-of-2 vector size without having the power of 2
734 // also be legal.
735 while (logCandidateNumElts > 0) {
736 assert(candidateNumElts == 1U << logCandidateNumElts);
737 assert(candidateNumElts <= numElts);
738 assert(candidateSize == eltSize * candidateNumElts);
739
740 // Skip illegal vector sizes.
741 if (!isLegalVectorType(CGM, candidateSize, eltTy, candidateNumElts)) {
742 logCandidateNumElts--;
743 candidateNumElts /= 2;
744 candidateSize /= 2;
745 continue;
746 }
747
748 // Add the right number of vectors of this size.
749 auto numVecs = numElts >> logCandidateNumElts;
750 components.append(numVecs,
751 llvm::FixedVectorType::get(eltTy, candidateNumElts));
752 numElts -= (numVecs << logCandidateNumElts);
753
754 if (numElts == 0) return;
755
756 // It's possible that the number of elements remaining will be legal.
757 // This can happen with e.g. <7 x float> when <3 x float> is legal.
758 // This only needs to be separately checked if it's not a power of 2.
759 if (numElts > 2 && !isPowerOf2(numElts) &&
760 isLegalVectorType(CGM, eltSize * numElts, eltTy, numElts)) {
761 components.push_back(llvm::FixedVectorType::get(eltTy, numElts));
762 return;
763 }
764
765 // Bring vecSize down to something no larger than numElts.
766 do {
767 logCandidateNumElts--;
768 candidateNumElts /= 2;
769 candidateSize /= 2;
770 } while (candidateNumElts > numElts);
771 }
772
773 // Otherwise, just append a bunch of individual elements.
774 components.append(numElts, eltTy);
775 }
776
mustPassRecordIndirectly(CodeGenModule & CGM,const RecordDecl * record)777 bool swiftcall::mustPassRecordIndirectly(CodeGenModule &CGM,
778 const RecordDecl *record) {
779 // FIXME: should we not rely on the standard computation in Sema, just in
780 // case we want to diverge from the platform ABI (e.g. on targets where
781 // that uses the MSVC rule)?
782 return !record->canPassInRegisters();
783 }
784
classifyExpandedType(SwiftAggLowering & lowering,bool forReturn,CharUnits alignmentForIndirect)785 static ABIArgInfo classifyExpandedType(SwiftAggLowering &lowering,
786 bool forReturn,
787 CharUnits alignmentForIndirect) {
788 if (lowering.empty()) {
789 return ABIArgInfo::getIgnore();
790 } else if (lowering.shouldPassIndirectly(forReturn)) {
791 return ABIArgInfo::getIndirect(alignmentForIndirect, /*byval*/ false);
792 } else {
793 auto types = lowering.getCoerceAndExpandTypes();
794 return ABIArgInfo::getCoerceAndExpand(types.first, types.second);
795 }
796 }
797
classifyType(CodeGenModule & CGM,CanQualType type,bool forReturn)798 static ABIArgInfo classifyType(CodeGenModule &CGM, CanQualType type,
799 bool forReturn) {
800 if (auto recordType = dyn_cast<RecordType>(type)) {
801 auto record = recordType->getDecl();
802 auto &layout = CGM.getContext().getASTRecordLayout(record);
803
804 if (mustPassRecordIndirectly(CGM, record))
805 return ABIArgInfo::getIndirect(layout.getAlignment(), /*byval*/ false);
806
807 SwiftAggLowering lowering(CGM);
808 lowering.addTypedData(recordType->getDecl(), CharUnits::Zero(), layout);
809 lowering.finish();
810
811 return classifyExpandedType(lowering, forReturn, layout.getAlignment());
812 }
813
814 // Just assume that all of our target ABIs can support returning at least
815 // two integer or floating-point values.
816 if (isa<ComplexType>(type)) {
817 return (forReturn ? ABIArgInfo::getDirect() : ABIArgInfo::getExpand());
818 }
819
820 // Vector types may need to be legalized.
821 if (isa<VectorType>(type)) {
822 SwiftAggLowering lowering(CGM);
823 lowering.addTypedData(type, CharUnits::Zero());
824 lowering.finish();
825
826 CharUnits alignment = CGM.getContext().getTypeAlignInChars(type);
827 return classifyExpandedType(lowering, forReturn, alignment);
828 }
829
830 // Member pointer types need to be expanded, but it's a simple form of
831 // expansion that 'Direct' can handle. Note that CanBeFlattened should be
832 // true for this to work.
833
834 // 'void' needs to be ignored.
835 if (type->isVoidType()) {
836 return ABIArgInfo::getIgnore();
837 }
838
839 // Everything else can be passed directly.
840 return ABIArgInfo::getDirect();
841 }
842
classifyReturnType(CodeGenModule & CGM,CanQualType type)843 ABIArgInfo swiftcall::classifyReturnType(CodeGenModule &CGM, CanQualType type) {
844 return classifyType(CGM, type, /*forReturn*/ true);
845 }
846
classifyArgumentType(CodeGenModule & CGM,CanQualType type)847 ABIArgInfo swiftcall::classifyArgumentType(CodeGenModule &CGM,
848 CanQualType type) {
849 return classifyType(CGM, type, /*forReturn*/ false);
850 }
851
computeABIInfo(CodeGenModule & CGM,CGFunctionInfo & FI)852 void swiftcall::computeABIInfo(CodeGenModule &CGM, CGFunctionInfo &FI) {
853 auto &retInfo = FI.getReturnInfo();
854 retInfo = classifyReturnType(CGM, FI.getReturnType());
855
856 for (unsigned i = 0, e = FI.arg_size(); i != e; ++i) {
857 auto &argInfo = FI.arg_begin()[i];
858 argInfo.info = classifyArgumentType(CGM, argInfo.type);
859 }
860 }
861
862 // Is swifterror lowered to a register by the target ABI.
isSwiftErrorLoweredInRegister(CodeGenModule & CGM)863 bool swiftcall::isSwiftErrorLoweredInRegister(CodeGenModule &CGM) {
864 return getSwiftABIInfo(CGM).isSwiftErrorInRegister();
865 }
866