1 //===-- DataLayout.cpp - Data size & alignment routines --------------------==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines layout properties related to datatype size/offset/alignment
13 // This structure should be created once, filled in if the defaults are not
14 // correct and then passed around by const&. None of the members functions
15 // require modification to the object.
17 //===----------------------------------------------------------------------===//
19 #include "llvm/DataLayout.h"
20 #include "llvm/Constants.h"
21 #include "llvm/DerivedTypes.h"
22 #include "llvm/Module.h"
23 #include "llvm/Support/GetElementPtrTypeIterator.h"
24 #include "llvm/Support/MathExtras.h"
25 #include "llvm/Support/ManagedStatic.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Support/raw_ostream.h"
28 #include "llvm/Support/Mutex.h"
29 #include "llvm/ADT/DenseMap.h"
34 // Handle the Pass registration stuff necessary to use DataLayout's.
36 // Register the default SparcV9 implementation...
37 INITIALIZE_PASS(DataLayout, "datalayout", "Data Layout", false, true)
38 char DataLayout::ID = 0;
40 //===----------------------------------------------------------------------===//
41 // Support for StructLayout
42 //===----------------------------------------------------------------------===//
44 StructLayout::StructLayout(StructType *ST, const DataLayout &TD) {
45 assert(!ST->isOpaque() && "Cannot get layout of opaque structs");
48 NumElements = ST->getNumElements();
50 // Loop over each of the elements, placing them in memory.
51 for (unsigned i = 0, e = NumElements; i != e; ++i) {
52 Type *Ty = ST->getElementType(i);
53 unsigned TyAlign = ST->isPacked() ? 1 : TD.getABITypeAlignment(Ty);
55 // Add padding if necessary to align the data element properly.
56 if ((StructSize & (TyAlign-1)) != 0)
57 StructSize = DataLayout::RoundUpAlignment(StructSize, TyAlign);
59 // Keep track of maximum alignment constraint.
60 StructAlignment = std::max(TyAlign, StructAlignment);
62 MemberOffsets[i] = StructSize;
63 StructSize += TD.getTypeAllocSize(Ty); // Consume space for this data item
66 // Empty structures have alignment of 1 byte.
67 if (StructAlignment == 0) StructAlignment = 1;
69 // Add padding to the end of the struct so that it could be put in an array
70 // and all array elements would be aligned correctly.
71 if ((StructSize & (StructAlignment-1)) != 0)
72 StructSize = DataLayout::RoundUpAlignment(StructSize, StructAlignment);
76 /// getElementContainingOffset - Given a valid offset into the structure,
77 /// return the structure index that contains it.
78 unsigned StructLayout::getElementContainingOffset(uint64_t Offset) const {
80 std::upper_bound(&MemberOffsets[0], &MemberOffsets[NumElements], Offset);
81 assert(SI != &MemberOffsets[0] && "Offset not in structure type!");
83 assert(*SI <= Offset && "upper_bound didn't work");
84 assert((SI == &MemberOffsets[0] || *(SI-1) <= Offset) &&
85 (SI+1 == &MemberOffsets[NumElements] || *(SI+1) > Offset) &&
86 "Upper bound didn't work!");
88 // Multiple fields can have the same offset if any of them are zero sized.
89 // For example, in { i32, [0 x i32], i32 }, searching for offset 4 will stop
90 // at the i32 element, because it is the last element at that offset. This is
91 // the right one to return, because anything after it will have a higher
92 // offset, implying that this element is non-empty.
93 return SI-&MemberOffsets[0];
96 //===----------------------------------------------------------------------===//
97 // LayoutAlignElem, LayoutAlign support
98 //===----------------------------------------------------------------------===//
101 LayoutAlignElem::get(AlignTypeEnum align_type, unsigned abi_align,
102 unsigned pref_align, uint32_t bit_width) {
103 assert(abi_align <= pref_align && "Preferred alignment worse than ABI!");
104 LayoutAlignElem retval;
105 retval.AlignType = align_type;
106 retval.ABIAlign = abi_align;
107 retval.PrefAlign = pref_align;
108 retval.TypeBitWidth = bit_width;
113 LayoutAlignElem::operator==(const LayoutAlignElem &rhs) const {
114 return (AlignType == rhs.AlignType
115 && ABIAlign == rhs.ABIAlign
116 && PrefAlign == rhs.PrefAlign
117 && TypeBitWidth == rhs.TypeBitWidth);
120 const LayoutAlignElem
121 DataLayout::InvalidAlignmentElem =
122 LayoutAlignElem::get((AlignTypeEnum) -1, 0, 0, 0);
124 //===----------------------------------------------------------------------===//
125 // PointerAlignElem, PointerAlign support
126 //===----------------------------------------------------------------------===//
129 PointerAlignElem::get(uint32_t addr_space, unsigned abi_align,
130 unsigned pref_align, uint32_t bit_width) {
131 assert(abi_align <= pref_align && "Preferred alignment worse than ABI!");
132 PointerAlignElem retval;
133 retval.AddressSpace = addr_space;
134 retval.ABIAlign = abi_align;
135 retval.PrefAlign = pref_align;
136 retval.TypeBitWidth = bit_width;
141 PointerAlignElem::operator==(const PointerAlignElem &rhs) const {
142 return (ABIAlign == rhs.ABIAlign
143 && AddressSpace == rhs.AddressSpace
144 && PrefAlign == rhs.PrefAlign
145 && TypeBitWidth == rhs.TypeBitWidth);
148 const PointerAlignElem
149 DataLayout::InvalidPointerElem = PointerAlignElem::get(~0U, 0U, 0U, 0U);
151 //===----------------------------------------------------------------------===//
152 // DataLayout Class Implementation
153 //===----------------------------------------------------------------------===//
155 /// getInt - Get an integer ignoring errors.
156 static int getInt(StringRef R) {
158 R.getAsInteger(10, Result);
162 void DataLayout::init() {
163 initializeDataLayoutPass(*PassRegistry::getPassRegistry());
166 LittleEndian = false;
167 StackNaturalAlign = 0;
169 // Default alignments
170 setAlignment(INTEGER_ALIGN, 1, 1, 1); // i1
171 setAlignment(INTEGER_ALIGN, 1, 1, 8); // i8
172 setAlignment(INTEGER_ALIGN, 2, 2, 16); // i16
173 setAlignment(INTEGER_ALIGN, 4, 4, 32); // i32
174 setAlignment(INTEGER_ALIGN, 4, 8, 64); // i64
175 setAlignment(FLOAT_ALIGN, 2, 2, 16); // half
176 setAlignment(FLOAT_ALIGN, 4, 4, 32); // float
177 setAlignment(FLOAT_ALIGN, 8, 8, 64); // double
178 setAlignment(FLOAT_ALIGN, 16, 16, 128); // ppcf128, quad, ...
179 setAlignment(VECTOR_ALIGN, 8, 8, 64); // v2i32, v1i64, ...
180 setAlignment(VECTOR_ALIGN, 16, 16, 128); // v16i8, v8i16, v4i32, ...
181 setAlignment(AGGREGATE_ALIGN, 0, 8, 0); // struct
182 setPointerAlignment(0, 8, 8, 8);
185 std::string DataLayout::parseSpecifier(StringRef Desc, DataLayout *td) {
190 while (!Desc.empty()) {
191 std::pair<StringRef, StringRef> Split = Desc.split('-');
192 StringRef Token = Split.first;
198 Split = Token.split(':');
199 StringRef Specifier = Split.first;
200 Token = Split.second;
202 assert(!Specifier.empty() && "Can't be empty here");
204 switch (Specifier[0]) {
207 td->LittleEndian = false;
211 td->LittleEndian = true;
215 if (Specifier.size() > 1) {
216 AddrSpace = getInt(Specifier.substr(1));
217 if (AddrSpace < 0 || AddrSpace > (1 << 24))
218 return "Invalid address space, must be a positive 24bit integer";
220 Split = Token.split(':');
221 int PointerMemSizeBits = getInt(Split.first);
222 if (PointerMemSizeBits < 0 || PointerMemSizeBits % 8 != 0)
223 return "invalid pointer size, must be a positive 8-bit multiple";
225 // Pointer ABI alignment.
226 Split = Split.second.split(':');
227 int PointerABIAlignBits = getInt(Split.first);
228 if (PointerABIAlignBits < 0 || PointerABIAlignBits % 8 != 0) {
229 return "invalid pointer ABI alignment, "
230 "must be a positive 8-bit multiple";
233 // Pointer preferred alignment.
234 Split = Split.second.split(':');
235 int PointerPrefAlignBits = getInt(Split.first);
236 if (PointerPrefAlignBits < 0 || PointerPrefAlignBits % 8 != 0) {
237 return "invalid pointer preferred alignment, "
238 "must be a positive 8-bit multiple";
241 if (PointerPrefAlignBits == 0)
242 PointerPrefAlignBits = PointerABIAlignBits;
244 td->setPointerAlignment(AddrSpace, PointerABIAlignBits/8,
245 PointerPrefAlignBits/8, PointerMemSizeBits/8);
253 AlignTypeEnum AlignType;
254 char field = Specifier[0];
257 case 'i': AlignType = INTEGER_ALIGN; break;
258 case 'v': AlignType = VECTOR_ALIGN; break;
259 case 'f': AlignType = FLOAT_ALIGN; break;
260 case 'a': AlignType = AGGREGATE_ALIGN; break;
261 case 's': AlignType = STACK_ALIGN; break;
263 int Size = getInt(Specifier.substr(1));
265 return std::string("invalid ") + field + "-size field, "
269 Split = Token.split(':');
270 int ABIAlignBits = getInt(Split.first);
271 if (ABIAlignBits < 0 || ABIAlignBits % 8 != 0) {
272 return std::string("invalid ") + field +"-abi-alignment field, "
273 "must be a positive 8-bit multiple";
275 unsigned ABIAlign = ABIAlignBits / 8;
277 Split = Split.second.split(':');
279 int PrefAlignBits = getInt(Split.first);
280 if (PrefAlignBits < 0 || PrefAlignBits % 8 != 0) {
281 return std::string("invalid ") + field +"-preferred-alignment field, "
282 "must be a positive 8-bit multiple";
284 unsigned PrefAlign = PrefAlignBits / 8;
286 PrefAlign = ABIAlign;
289 td->setAlignment(AlignType, ABIAlign, PrefAlign, Size);
292 case 'n': // Native integer types.
293 Specifier = Specifier.substr(1);
295 int Width = getInt(Specifier);
297 return std::string("invalid native integer size \'") +
298 Specifier.str() + "\', must be a positive integer.";
300 if (td && Width != 0)
301 td->LegalIntWidths.push_back(Width);
302 Split = Token.split(':');
303 Specifier = Split.first;
304 Token = Split.second;
305 } while (!Specifier.empty() || !Token.empty());
307 case 'S': { // Stack natural alignment.
308 int StackNaturalAlignBits = getInt(Specifier.substr(1));
309 if (StackNaturalAlignBits < 0 || StackNaturalAlignBits % 8 != 0) {
310 return "invalid natural stack alignment (S-field), "
311 "must be a positive 8-bit multiple";
314 td->StackNaturalAlign = StackNaturalAlignBits / 8;
327 /// @note This has to exist, because this is a pass, but it should never be
329 DataLayout::DataLayout() : ImmutablePass(ID) {
330 report_fatal_error("Bad DataLayout ctor used. "
331 "Tool did not specify a DataLayout to use?");
334 DataLayout::DataLayout(const Module *M)
335 : ImmutablePass(ID) {
336 std::string errMsg = parseSpecifier(M->getDataLayout(), this);
337 assert(errMsg == "" && "Module M has malformed data layout string.");
342 DataLayout::setAlignment(AlignTypeEnum align_type, unsigned abi_align,
343 unsigned pref_align, uint32_t bit_width) {
344 assert(abi_align <= pref_align && "Preferred alignment worse than ABI!");
345 assert(pref_align < (1 << 16) && "Alignment doesn't fit in bitfield");
346 assert(bit_width < (1 << 24) && "Bit width doesn't fit in bitfield");
347 for (unsigned i = 0, e = Alignments.size(); i != e; ++i) {
348 if (Alignments[i].AlignType == (unsigned)align_type &&
349 Alignments[i].TypeBitWidth == bit_width) {
350 // Update the abi, preferred alignments.
351 Alignments[i].ABIAlign = abi_align;
352 Alignments[i].PrefAlign = pref_align;
357 Alignments.push_back(LayoutAlignElem::get(align_type, abi_align,
358 pref_align, bit_width));
362 DataLayout::setPointerAlignment(uint32_t addr_space, unsigned abi_align,
363 unsigned pref_align, uint32_t bit_width) {
364 assert(abi_align <= pref_align && "Preferred alignment worse than ABI!");
365 DenseMap<unsigned,PointerAlignElem>::iterator val = Pointers.find(addr_space);
366 if (val == Pointers.end()) {
367 Pointers[addr_space] = PointerAlignElem::get(addr_space,
368 abi_align, pref_align, bit_width);
370 val->second.ABIAlign = abi_align;
371 val->second.PrefAlign = pref_align;
372 val->second.TypeBitWidth = bit_width;
376 /// getAlignmentInfo - Return the alignment (either ABI if ABIInfo = true or
377 /// preferred if ABIInfo = false) the layout wants for the specified datatype.
378 unsigned DataLayout::getAlignmentInfo(AlignTypeEnum AlignType,
379 uint32_t BitWidth, bool ABIInfo,
381 // Check to see if we have an exact match and remember the best match we see.
382 int BestMatchIdx = -1;
384 for (unsigned i = 0, e = Alignments.size(); i != e; ++i) {
385 if (Alignments[i].AlignType == (unsigned)AlignType &&
386 Alignments[i].TypeBitWidth == BitWidth)
387 return ABIInfo ? Alignments[i].ABIAlign : Alignments[i].PrefAlign;
389 // The best match so far depends on what we're looking for.
390 if (AlignType == INTEGER_ALIGN &&
391 Alignments[i].AlignType == INTEGER_ALIGN) {
392 // The "best match" for integers is the smallest size that is larger than
393 // the BitWidth requested.
394 if (Alignments[i].TypeBitWidth > BitWidth && (BestMatchIdx == -1 ||
395 Alignments[i].TypeBitWidth < Alignments[BestMatchIdx].TypeBitWidth))
397 // However, if there isn't one that's larger, then we must use the
398 // largest one we have (see below)
399 if (LargestInt == -1 ||
400 Alignments[i].TypeBitWidth > Alignments[LargestInt].TypeBitWidth)
405 // Okay, we didn't find an exact solution. Fall back here depending on what
406 // is being looked for.
407 if (BestMatchIdx == -1) {
408 // If we didn't find an integer alignment, fall back on most conservative.
409 if (AlignType == INTEGER_ALIGN) {
410 BestMatchIdx = LargestInt;
412 assert(AlignType == VECTOR_ALIGN && "Unknown alignment type!");
414 // By default, use natural alignment for vector types. This is consistent
415 // with what clang and llvm-gcc do.
416 unsigned Align = getTypeAllocSize(cast<VectorType>(Ty)->getElementType());
417 Align *= cast<VectorType>(Ty)->getNumElements();
418 // If the alignment is not a power of 2, round up to the next power of 2.
419 // This happens for non-power-of-2 length vectors.
420 if (Align & (Align-1))
421 Align = NextPowerOf2(Align);
426 // Since we got a "best match" index, just return it.
427 return ABIInfo ? Alignments[BestMatchIdx].ABIAlign
428 : Alignments[BestMatchIdx].PrefAlign;
433 class StructLayoutMap {
434 typedef DenseMap<StructType*, StructLayout*> LayoutInfoTy;
435 LayoutInfoTy LayoutInfo;
438 virtual ~StructLayoutMap() {
439 // Remove any layouts.
440 for (LayoutInfoTy::iterator I = LayoutInfo.begin(), E = LayoutInfo.end();
442 StructLayout *Value = I->second;
443 Value->~StructLayout();
448 StructLayout *&operator[](StructType *STy) {
449 return LayoutInfo[STy];
453 virtual void dump() const {}
456 } // end anonymous namespace
458 DataLayout::~DataLayout() {
459 delete static_cast<StructLayoutMap*>(LayoutMap);
462 const StructLayout *DataLayout::getStructLayout(StructType *Ty) const {
464 LayoutMap = new StructLayoutMap();
466 StructLayoutMap *STM = static_cast<StructLayoutMap*>(LayoutMap);
467 StructLayout *&SL = (*STM)[Ty];
470 // Otherwise, create the struct layout. Because it is variable length, we
471 // malloc it, then use placement new.
472 int NumElts = Ty->getNumElements();
474 (StructLayout *)malloc(sizeof(StructLayout)+(NumElts-1) * sizeof(uint64_t));
476 // Set SL before calling StructLayout's ctor. The ctor could cause other
477 // entries to be added to TheMap, invalidating our reference.
480 new (L) StructLayout(Ty, *this);
485 std::string DataLayout::getStringRepresentation() const {
487 raw_string_ostream OS(Result);
489 OS << (LittleEndian ? "e" : "E");
490 SmallVector<unsigned, 8> addrSpaces;
491 // Lets get all of the known address spaces and sort them
492 // into increasing order so that we can emit the string
493 // in a cleaner format.
494 for (DenseMap<unsigned, PointerAlignElem>::const_iterator
495 pib = Pointers.begin(), pie = Pointers.end();
497 addrSpaces.push_back(pib->first);
499 std::sort(addrSpaces.begin(), addrSpaces.end());
500 for (SmallVector<unsigned, 8>::iterator asb = addrSpaces.begin(),
501 ase = addrSpaces.end(); asb != ase; ++asb) {
502 const PointerAlignElem &PI = Pointers.find(*asb)->second;
504 if (PI.AddressSpace) {
505 OS << PI.AddressSpace;
507 OS << ":" << PI.TypeBitWidth*8 << ':' << PI.ABIAlign*8
508 << ':' << PI.PrefAlign*8;
510 OS << "-S" << StackNaturalAlign*8;
512 for (unsigned i = 0, e = Alignments.size(); i != e; ++i) {
513 const LayoutAlignElem &AI = Alignments[i];
514 OS << '-' << (char)AI.AlignType << AI.TypeBitWidth << ':'
515 << AI.ABIAlign*8 << ':' << AI.PrefAlign*8;
518 if (!LegalIntWidths.empty()) {
519 OS << "-n" << (unsigned)LegalIntWidths[0];
521 for (unsigned i = 1, e = LegalIntWidths.size(); i != e; ++i)
522 OS << ':' << (unsigned)LegalIntWidths[i];
528 uint64_t DataLayout::getTypeSizeInBits(Type *Ty) const {
529 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
530 switch (Ty->getTypeID()) {
531 case Type::LabelTyID:
532 return getPointerSizeInBits(0);
533 case Type::PointerTyID: {
534 unsigned AS = dyn_cast<PointerType>(Ty)->getAddressSpace();
535 return getPointerSizeInBits(AS);
537 case Type::ArrayTyID: {
538 ArrayType *ATy = cast<ArrayType>(Ty);
539 return getTypeAllocSizeInBits(ATy->getElementType())*ATy->getNumElements();
541 case Type::StructTyID:
542 // Get the layout annotation... which is lazily created on demand.
543 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
544 case Type::IntegerTyID:
545 return cast<IntegerType>(Ty)->getBitWidth();
550 case Type::FloatTyID:
552 case Type::DoubleTyID:
553 case Type::X86_MMXTyID:
555 case Type::PPC_FP128TyID:
556 case Type::FP128TyID:
558 // In memory objects this is always aligned to a higher boundary, but
559 // only 80 bits contain information.
560 case Type::X86_FP80TyID:
562 case Type::VectorTyID: {
563 VectorType *VTy = cast<VectorType>(Ty);
564 return VTy->getNumElements()*getTypeSizeInBits(VTy->getElementType());
567 llvm_unreachable("DataLayout::getTypeSizeInBits(): Unsupported type");
572 \param abi_or_pref Flag that determines which alignment is returned. true
573 returns the ABI alignment, false returns the preferred alignment.
574 \param Ty The underlying type for which alignment is determined.
576 Get the ABI (\a abi_or_pref == true) or preferred alignment (\a abi_or_pref
577 == false) for the requested type \a Ty.
579 unsigned DataLayout::getAlignment(Type *Ty, bool abi_or_pref) const {
582 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
583 switch (Ty->getTypeID()) {
584 // Early escape for the non-numeric types.
585 case Type::LabelTyID:
587 ? getPointerABIAlignment(0)
588 : getPointerPrefAlignment(0));
589 case Type::PointerTyID: {
590 unsigned AS = dyn_cast<PointerType>(Ty)->getAddressSpace();
592 ? getPointerABIAlignment(AS)
593 : getPointerPrefAlignment(AS));
595 case Type::ArrayTyID:
596 return getAlignment(cast<ArrayType>(Ty)->getElementType(), abi_or_pref);
598 case Type::StructTyID: {
599 // Packed structure types always have an ABI alignment of one.
600 if (cast<StructType>(Ty)->isPacked() && abi_or_pref)
603 // Get the layout annotation... which is lazily created on demand.
604 const StructLayout *Layout = getStructLayout(cast<StructType>(Ty));
605 unsigned Align = getAlignmentInfo(AGGREGATE_ALIGN, 0, abi_or_pref, Ty);
606 return std::max(Align, Layout->getAlignment());
608 case Type::IntegerTyID:
610 AlignType = INTEGER_ALIGN;
613 case Type::FloatTyID:
614 case Type::DoubleTyID:
615 // PPC_FP128TyID and FP128TyID have different data contents, but the
616 // same size and alignment, so they look the same here.
617 case Type::PPC_FP128TyID:
618 case Type::FP128TyID:
619 case Type::X86_FP80TyID:
620 AlignType = FLOAT_ALIGN;
622 case Type::X86_MMXTyID:
623 case Type::VectorTyID:
624 AlignType = VECTOR_ALIGN;
627 llvm_unreachable("Bad type for getAlignment!!!");
630 return getAlignmentInfo((AlignTypeEnum)AlignType, getTypeSizeInBits(Ty),
634 unsigned DataLayout::getABITypeAlignment(Type *Ty) const {
635 return getAlignment(Ty, true);
638 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for
639 /// an integer type of the specified bitwidth.
640 unsigned DataLayout::getABIIntegerTypeAlignment(unsigned BitWidth) const {
641 return getAlignmentInfo(INTEGER_ALIGN, BitWidth, true, 0);
645 unsigned DataLayout::getCallFrameTypeAlignment(Type *Ty) const {
646 for (unsigned i = 0, e = Alignments.size(); i != e; ++i)
647 if (Alignments[i].AlignType == STACK_ALIGN)
648 return Alignments[i].ABIAlign;
650 return getABITypeAlignment(Ty);
653 unsigned DataLayout::getPrefTypeAlignment(Type *Ty) const {
654 return getAlignment(Ty, false);
657 unsigned DataLayout::getPreferredTypeAlignmentShift(Type *Ty) const {
658 unsigned Align = getPrefTypeAlignment(Ty);
659 assert(!(Align & (Align-1)) && "Alignment is not a power of two!");
660 return Log2_32(Align);
663 /// getIntPtrType - Return an integer type with size at least as big as that
664 /// of a pointer in the given address space.
665 IntegerType *DataLayout::getIntPtrType(LLVMContext &C,
666 unsigned AddressSpace) const {
667 return IntegerType::get(C, getPointerSizeInBits(AddressSpace));
670 /// getIntPtrType - Return an integer (vector of integer) type with size at
671 /// least as big as that of a pointer of the given pointer (vector of pointer)
673 Type *DataLayout::getIntPtrType(Type *Ty) const {
674 assert(Ty->isPtrOrPtrVectorTy() &&
675 "Expected a pointer or pointer vector type.");
676 unsigned NumBits = getTypeSizeInBits(Ty->getScalarType());
677 IntegerType *IntTy = IntegerType::get(Ty->getContext(), NumBits);
678 if (VectorType *VecTy = dyn_cast<VectorType>(Ty))
679 return VectorType::get(IntTy, VecTy->getNumElements());
683 uint64_t DataLayout::getIndexedOffset(Type *ptrTy,
684 ArrayRef<Value *> Indices) const {
686 assert(Ty->isPointerTy() && "Illegal argument for getIndexedOffset()");
689 generic_gep_type_iterator<Value* const*>
690 TI = gep_type_begin(ptrTy, Indices);
691 for (unsigned CurIDX = 0, EndIDX = Indices.size(); CurIDX != EndIDX;
693 if (StructType *STy = dyn_cast<StructType>(*TI)) {
694 assert(Indices[CurIDX]->getType() ==
695 Type::getInt32Ty(ptrTy->getContext()) &&
696 "Illegal struct idx");
697 unsigned FieldNo = cast<ConstantInt>(Indices[CurIDX])->getZExtValue();
699 // Get structure layout information...
700 const StructLayout *Layout = getStructLayout(STy);
702 // Add in the offset, as calculated by the structure layout info...
703 Result += Layout->getElementOffset(FieldNo);
705 // Update Ty to refer to current element
706 Ty = STy->getElementType(FieldNo);
708 // Update Ty to refer to current element
709 Ty = cast<SequentialType>(Ty)->getElementType();
711 // Get the array index and the size of each array element.
712 if (int64_t arrayIdx = cast<ConstantInt>(Indices[CurIDX])->getSExtValue())
713 Result += (uint64_t)arrayIdx * getTypeAllocSize(Ty);
720 /// getPreferredAlignment - Return the preferred alignment of the specified
721 /// global. This includes an explicitly requested alignment (if the global
723 unsigned DataLayout::getPreferredAlignment(const GlobalVariable *GV) const {
724 Type *ElemType = GV->getType()->getElementType();
725 unsigned Alignment = getPrefTypeAlignment(ElemType);
726 unsigned GVAlignment = GV->getAlignment();
727 if (GVAlignment >= Alignment) {
728 Alignment = GVAlignment;
729 } else if (GVAlignment != 0) {
730 Alignment = std::max(GVAlignment, getABITypeAlignment(ElemType));
733 if (GV->hasInitializer() && GVAlignment == 0) {
734 if (Alignment < 16) {
735 // If the global is not external, see if it is large. If so, give it a
737 if (getTypeSizeInBits(ElemType) > 128)
738 Alignment = 16; // 16-byte alignment.
744 /// getPreferredAlignmentLog - Return the preferred alignment of the
745 /// specified global, returned in log form. This includes an explicitly
746 /// requested alignment (if the global has one).
747 unsigned DataLayout::getPreferredAlignmentLog(const GlobalVariable *GV) const {
748 return Log2_32(getPreferredAlignment(GV));