1 //===-- TargetData.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 target 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/Target/TargetData.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/System/Mutex.h"
29 #include "llvm/ADT/DenseMap.h"
34 // Handle the Pass registration stuff necessary to use TargetData's.
36 // Register the default SparcV9 implementation...
37 static RegisterPass<TargetData> X("targetdata", "Target Data Layout", false,
39 char TargetData::ID = 0;
41 //===----------------------------------------------------------------------===//
42 // Support for StructLayout
43 //===----------------------------------------------------------------------===//
45 StructLayout::StructLayout(const StructType *ST, const TargetData &TD) {
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 const 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 = TargetData::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 = TargetData::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 // TargetAlignElem, TargetAlign support
98 //===----------------------------------------------------------------------===//
101 TargetAlignElem::get(AlignTypeEnum align_type, unsigned char abi_align,
102 unsigned char pref_align, uint32_t bit_width) {
103 assert(abi_align <= pref_align && "Preferred alignment worse than ABI!");
104 TargetAlignElem retval;
105 retval.AlignType = align_type;
106 retval.ABIAlign = abi_align;
107 retval.PrefAlign = pref_align;
108 retval.TypeBitWidth = bit_width;
113 TargetAlignElem::operator==(const TargetAlignElem &rhs) const {
114 return (AlignType == rhs.AlignType
115 && ABIAlign == rhs.ABIAlign
116 && PrefAlign == rhs.PrefAlign
117 && TypeBitWidth == rhs.TypeBitWidth);
120 const TargetAlignElem TargetData::InvalidAlignmentElem =
121 TargetAlignElem::get((AlignTypeEnum) -1, 0, 0, 0);
123 //===----------------------------------------------------------------------===//
124 // TargetData Class Implementation
125 //===----------------------------------------------------------------------===//
127 /// getInt - Get an integer ignoring errors.
128 static unsigned getInt(StringRef R) {
130 R.getAsInteger(10, Result);
134 void TargetData::init(StringRef Desc) {
136 LittleEndian = false;
139 PointerPrefAlign = PointerABIAlign;
141 // Default alignments
142 setAlignment(INTEGER_ALIGN, 1, 1, 1); // i1
143 setAlignment(INTEGER_ALIGN, 1, 1, 8); // i8
144 setAlignment(INTEGER_ALIGN, 2, 2, 16); // i16
145 setAlignment(INTEGER_ALIGN, 4, 4, 32); // i32
146 setAlignment(INTEGER_ALIGN, 4, 8, 64); // i64
147 setAlignment(FLOAT_ALIGN, 4, 4, 32); // float
148 setAlignment(FLOAT_ALIGN, 8, 8, 64); // double
149 setAlignment(VECTOR_ALIGN, 8, 8, 64); // v2i32, v1i64, ...
150 setAlignment(VECTOR_ALIGN, 16, 16, 128); // v16i8, v8i16, v4i32, ...
151 setAlignment(AGGREGATE_ALIGN, 0, 8, 0); // struct
153 while (!Desc.empty()) {
154 std::pair<StringRef, StringRef> Split = Desc.split('-');
155 StringRef Token = Split.first;
161 Split = Token.split(':');
162 StringRef Specifier = Split.first;
163 Token = Split.second;
165 assert(!Specifier.empty() && "Can't be empty here");
167 switch (Specifier[0]) {
169 LittleEndian = false;
175 Split = Token.split(':');
176 PointerMemSize = getInt(Split.first) / 8;
177 Split = Split.second.split(':');
178 PointerABIAlign = getInt(Split.first) / 8;
179 Split = Split.second.split(':');
180 PointerPrefAlign = getInt(Split.first) / 8;
181 if (PointerPrefAlign == 0)
182 PointerPrefAlign = PointerABIAlign;
189 AlignTypeEnum AlignType;
190 switch (Specifier[0]) {
192 case 'i': AlignType = INTEGER_ALIGN; break;
193 case 'v': AlignType = VECTOR_ALIGN; break;
194 case 'f': AlignType = FLOAT_ALIGN; break;
195 case 'a': AlignType = AGGREGATE_ALIGN; break;
196 case 's': AlignType = STACK_ALIGN; break;
198 unsigned Size = getInt(Specifier.substr(1));
199 Split = Token.split(':');
200 unsigned char ABIAlign = getInt(Split.first) / 8;
202 Split = Split.second.split(':');
203 unsigned char PrefAlign = getInt(Split.first) / 8;
205 PrefAlign = ABIAlign;
206 setAlignment(AlignType, ABIAlign, PrefAlign, Size);
209 case 'n': // Native integer types.
210 Specifier = Specifier.substr(1);
212 if (unsigned Width = getInt(Specifier))
213 LegalIntWidths.push_back(Width);
214 Split = Token.split(':');
215 Specifier = Split.first;
216 Token = Split.second;
217 } while (!Specifier.empty() || !Token.empty());
228 /// @note This has to exist, because this is a pass, but it should never be
230 TargetData::TargetData() : ImmutablePass(&ID) {
231 llvm_report_error("Bad TargetData ctor used. "
232 "Tool did not specify a TargetData to use?");
235 TargetData::TargetData(const Module *M)
236 : ImmutablePass(&ID) {
237 init(M->getDataLayout());
241 TargetData::setAlignment(AlignTypeEnum align_type, unsigned char abi_align,
242 unsigned char pref_align, uint32_t bit_width) {
243 assert(abi_align <= pref_align && "Preferred alignment worse than ABI!");
244 for (unsigned i = 0, e = Alignments.size(); i != e; ++i) {
245 if (Alignments[i].AlignType == align_type &&
246 Alignments[i].TypeBitWidth == bit_width) {
247 // Update the abi, preferred alignments.
248 Alignments[i].ABIAlign = abi_align;
249 Alignments[i].PrefAlign = pref_align;
254 Alignments.push_back(TargetAlignElem::get(align_type, abi_align,
255 pref_align, bit_width));
258 /// getAlignmentInfo - Return the alignment (either ABI if ABIInfo = true or
259 /// preferred if ABIInfo = false) the target wants for the specified datatype.
260 unsigned TargetData::getAlignmentInfo(AlignTypeEnum AlignType,
261 uint32_t BitWidth, bool ABIInfo,
262 const Type *Ty) const {
263 // Check to see if we have an exact match and remember the best match we see.
264 int BestMatchIdx = -1;
266 for (unsigned i = 0, e = Alignments.size(); i != e; ++i) {
267 if (Alignments[i].AlignType == AlignType &&
268 Alignments[i].TypeBitWidth == BitWidth)
269 return ABIInfo ? Alignments[i].ABIAlign : Alignments[i].PrefAlign;
271 // The best match so far depends on what we're looking for.
272 if (AlignType == VECTOR_ALIGN && Alignments[i].AlignType == VECTOR_ALIGN) {
273 // If this is a specification for a smaller vector type, we will fall back
274 // to it. This happens because <128 x double> can be implemented in terms
275 // of 64 <2 x double>.
276 if (Alignments[i].TypeBitWidth < BitWidth) {
277 // Verify that we pick the biggest of the fallbacks.
278 if (BestMatchIdx == -1 ||
279 Alignments[BestMatchIdx].TypeBitWidth < Alignments[i].TypeBitWidth)
282 } else if (AlignType == INTEGER_ALIGN &&
283 Alignments[i].AlignType == INTEGER_ALIGN) {
284 // The "best match" for integers is the smallest size that is larger than
285 // the BitWidth requested.
286 if (Alignments[i].TypeBitWidth > BitWidth && (BestMatchIdx == -1 ||
287 Alignments[i].TypeBitWidth < Alignments[BestMatchIdx].TypeBitWidth))
289 // However, if there isn't one that's larger, then we must use the
290 // largest one we have (see below)
291 if (LargestInt == -1 ||
292 Alignments[i].TypeBitWidth > Alignments[LargestInt].TypeBitWidth)
297 // Okay, we didn't find an exact solution. Fall back here depending on what
298 // is being looked for.
299 if (BestMatchIdx == -1) {
300 // If we didn't find an integer alignment, fall back on most conservative.
301 if (AlignType == INTEGER_ALIGN) {
302 BestMatchIdx = LargestInt;
304 assert(AlignType == VECTOR_ALIGN && "Unknown alignment type!");
306 // If we didn't find a vector size that is smaller or equal to this type,
307 // then we will end up scalarizing this to its element type. Just return
308 // the alignment of the element.
309 return getAlignment(cast<VectorType>(Ty)->getElementType(), ABIInfo);
313 // Since we got a "best match" index, just return it.
314 return ABIInfo ? Alignments[BestMatchIdx].ABIAlign
315 : Alignments[BestMatchIdx].PrefAlign;
320 class StructLayoutMap : public AbstractTypeUser {
321 typedef DenseMap<const StructType*, StructLayout*> LayoutInfoTy;
322 LayoutInfoTy LayoutInfo;
324 void RemoveEntry(LayoutInfoTy::iterator I, bool WasAbstract) {
325 I->second->~StructLayout();
328 I->first->removeAbstractTypeUser(this);
333 /// refineAbstractType - The callback method invoked when an abstract type is
334 /// resolved to another type. An object must override this method to update
335 /// its internal state to reference NewType instead of OldType.
337 virtual void refineAbstractType(const DerivedType *OldTy,
339 LayoutInfoTy::iterator I = LayoutInfo.find(cast<const StructType>(OldTy));
340 assert(I != LayoutInfo.end() && "Using type but not in map?");
341 RemoveEntry(I, true);
344 /// typeBecameConcrete - The other case which AbstractTypeUsers must be aware
345 /// of is when a type makes the transition from being abstract (where it has
346 /// clients on its AbstractTypeUsers list) to concrete (where it does not).
347 /// This method notifies ATU's when this occurs for a type.
349 virtual void typeBecameConcrete(const DerivedType *AbsTy) {
350 LayoutInfoTy::iterator I = LayoutInfo.find(cast<const StructType>(AbsTy));
351 assert(I != LayoutInfo.end() && "Using type but not in map?");
352 RemoveEntry(I, true);
356 virtual ~StructLayoutMap() {
357 // Remove any layouts.
358 for (LayoutInfoTy::iterator
359 I = LayoutInfo.begin(), E = LayoutInfo.end(); I != E; ++I) {
360 const Type *Key = I->first;
361 StructLayout *Value = I->second;
363 if (Key->isAbstract())
364 Key->removeAbstractTypeUser(this);
366 Value->~StructLayout();
371 void InvalidateEntry(const StructType *Ty) {
372 LayoutInfoTy::iterator I = LayoutInfo.find(Ty);
373 if (I == LayoutInfo.end()) return;
374 RemoveEntry(I, Ty->isAbstract());
377 StructLayout *&operator[](const StructType *STy) {
378 return LayoutInfo[STy];
382 virtual void dump() const {}
385 } // end anonymous namespace
387 TargetData::~TargetData() {
388 delete static_cast<StructLayoutMap*>(LayoutMap);
391 const StructLayout *TargetData::getStructLayout(const StructType *Ty) const {
393 LayoutMap = new StructLayoutMap();
395 StructLayoutMap *STM = static_cast<StructLayoutMap*>(LayoutMap);
396 StructLayout *&SL = (*STM)[Ty];
399 // Otherwise, create the struct layout. Because it is variable length, we
400 // malloc it, then use placement new.
401 int NumElts = Ty->getNumElements();
403 (StructLayout *)malloc(sizeof(StructLayout)+(NumElts-1) * sizeof(uint64_t));
405 // Set SL before calling StructLayout's ctor. The ctor could cause other
406 // entries to be added to TheMap, invalidating our reference.
409 new (L) StructLayout(Ty, *this);
411 if (Ty->isAbstract())
412 Ty->addAbstractTypeUser(STM);
417 /// InvalidateStructLayoutInfo - TargetData speculatively caches StructLayout
418 /// objects. If a TargetData object is alive when types are being refined and
419 /// removed, this method must be called whenever a StructType is removed to
420 /// avoid a dangling pointer in this cache.
421 void TargetData::InvalidateStructLayoutInfo(const StructType *Ty) const {
422 if (!LayoutMap) return; // No cache.
424 static_cast<StructLayoutMap*>(LayoutMap)->InvalidateEntry(Ty);
427 std::string TargetData::getStringRepresentation() const {
429 raw_string_ostream OS(Result);
431 OS << (LittleEndian ? "e" : "E")
432 << "-p:" << PointerMemSize*8 << ':' << PointerABIAlign*8
433 << ':' << PointerPrefAlign*8;
434 for (unsigned i = 0, e = Alignments.size(); i != e; ++i) {
435 const TargetAlignElem &AI = Alignments[i];
436 OS << '-' << (char)AI.AlignType << AI.TypeBitWidth << ':'
437 << AI.ABIAlign*8 << ':' << AI.PrefAlign*8;
440 if (!LegalIntWidths.empty()) {
441 OS << "-n" << (unsigned)LegalIntWidths[0];
443 for (unsigned i = 1, e = LegalIntWidths.size(); i != e; ++i)
444 OS << ':' << (unsigned)LegalIntWidths[i];
450 uint64_t TargetData::getTypeSizeInBits(const Type *Ty) const {
451 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
452 switch (Ty->getTypeID()) {
453 case Type::LabelTyID:
454 case Type::PointerTyID:
455 return getPointerSizeInBits();
456 case Type::ArrayTyID: {
457 const ArrayType *ATy = cast<ArrayType>(Ty);
458 return getTypeSizeInBits(ATy->getElementType())*ATy->getNumElements();
460 case Type::StructTyID:
461 // Get the layout annotation... which is lazily created on demand.
462 return getStructLayout(cast<StructType>(Ty))->getSizeInBits();
463 case Type::IntegerTyID:
464 return cast<IntegerType>(Ty)->getBitWidth();
467 case Type::FloatTyID:
469 case Type::DoubleTyID:
471 case Type::PPC_FP128TyID:
472 case Type::FP128TyID:
474 // In memory objects this is always aligned to a higher boundary, but
475 // only 80 bits contain information.
476 case Type::X86_FP80TyID:
478 case Type::VectorTyID:
479 return cast<VectorType>(Ty)->getBitWidth();
481 llvm_unreachable("TargetData::getTypeSizeInBits(): Unsupported type");
487 /// getTypeStoreSize - Return the maximum number of bytes that may be
488 /// overwritten by storing the specified type. For example, returns 5
489 /// for i36 and 10 for x86_fp80.
490 uint64_t TargetData::getTypeStoreSize(const Type *Ty) const {
491 // Arrays and vectors are allocated as sequences of elements.
492 if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
493 if (ATy->getNumElements() == 0)
495 const Type *ElementType = ATy->getElementType();
496 return getTypeAllocSize(ElementType) * (ATy->getNumElements() - 1) +
497 getTypeStoreSize(ElementType);
499 if (const VectorType *VTy = dyn_cast<VectorType>(Ty)) {
500 const Type *ElementType = VTy->getElementType();
501 return getTypeAllocSize(ElementType) * (VTy->getNumElements() - 1) +
502 getTypeStoreSize(ElementType);
505 return (getTypeSizeInBits(Ty)+7)/8;
508 /// getTypeAllocSize - Return the offset in bytes between successive objects
509 /// of the specified type, including alignment padding. This is the amount
510 /// that alloca reserves for this type. For example, returns 12 or 16 for
511 /// x86_fp80, depending on alignment.
512 uint64_t TargetData::getTypeAllocSize(const Type* Ty) const {
513 // Arrays and vectors are allocated as sequences of elements.
514 // Note that this means that things like vectors-of-i1 are not bit-packed
515 // in memory (except on a hypothetical bit-addressable machine). If
516 // someone builds hardware with native vector-of-i1 stores and the idiom
517 // of bitcasting vectors to integers in order to bitpack them for storage
518 // isn't sufficient, TargetData may need new "size" concept.
519 if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty))
520 return getTypeAllocSize(ATy->getElementType()) * ATy->getNumElements();
521 if (const VectorType *VTy = dyn_cast<VectorType>(Ty))
522 return getTypeAllocSize(VTy->getElementType()) * VTy->getNumElements();
524 // Round up to the next alignment boundary.
525 return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
529 \param abi_or_pref Flag that determines which alignment is returned. true
530 returns the ABI alignment, false returns the preferred alignment.
531 \param Ty The underlying type for which alignment is determined.
533 Get the ABI (\a abi_or_pref == true) or preferred alignment (\a abi_or_pref
534 == false) for the requested type \a Ty.
536 unsigned char TargetData::getAlignment(const Type *Ty, bool abi_or_pref) const {
539 assert(Ty->isSized() && "Cannot getTypeInfo() on a type that is unsized!");
540 switch (Ty->getTypeID()) {
541 // Early escape for the non-numeric types.
542 case Type::LabelTyID:
543 case Type::PointerTyID:
545 ? getPointerABIAlignment()
546 : getPointerPrefAlignment());
547 case Type::ArrayTyID:
548 return getAlignment(cast<ArrayType>(Ty)->getElementType(), abi_or_pref);
550 case Type::StructTyID: {
551 // Packed structure types always have an ABI alignment of one.
552 if (cast<StructType>(Ty)->isPacked() && abi_or_pref)
555 // Get the layout annotation... which is lazily created on demand.
556 const StructLayout *Layout = getStructLayout(cast<StructType>(Ty));
557 unsigned Align = getAlignmentInfo(AGGREGATE_ALIGN, 0, abi_or_pref, Ty);
558 return std::max(Align, (unsigned)Layout->getAlignment());
560 case Type::IntegerTyID:
562 AlignType = INTEGER_ALIGN;
564 case Type::FloatTyID:
565 case Type::DoubleTyID:
566 // PPC_FP128TyID and FP128TyID have different data contents, but the
567 // same size and alignment, so they look the same here.
568 case Type::PPC_FP128TyID:
569 case Type::FP128TyID:
570 case Type::X86_FP80TyID:
571 AlignType = FLOAT_ALIGN;
573 case Type::VectorTyID:
574 AlignType = VECTOR_ALIGN;
577 llvm_unreachable("Bad type for getAlignment!!!");
581 return getAlignmentInfo((AlignTypeEnum)AlignType, getTypeSizeInBits(Ty),
585 unsigned char TargetData::getABITypeAlignment(const Type *Ty) const {
586 return getAlignment(Ty, true);
589 /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for
590 /// an integer type of the specified bitwidth.
591 unsigned char TargetData::getABIIntegerTypeAlignment(unsigned BitWidth) const {
592 return getAlignmentInfo(INTEGER_ALIGN, BitWidth, true, 0);
596 unsigned char TargetData::getCallFrameTypeAlignment(const Type *Ty) const {
597 for (unsigned i = 0, e = Alignments.size(); i != e; ++i)
598 if (Alignments[i].AlignType == STACK_ALIGN)
599 return Alignments[i].ABIAlign;
601 return getABITypeAlignment(Ty);
604 unsigned char TargetData::getPrefTypeAlignment(const Type *Ty) const {
605 return getAlignment(Ty, false);
608 unsigned char TargetData::getPreferredTypeAlignmentShift(const Type *Ty) const {
609 unsigned Align = (unsigned) getPrefTypeAlignment(Ty);
610 assert(!(Align & (Align-1)) && "Alignment is not a power of two!");
611 return Log2_32(Align);
614 /// getIntPtrType - Return an unsigned integer type that is the same size or
615 /// greater to the host pointer size.
616 const IntegerType *TargetData::getIntPtrType(LLVMContext &C) const {
617 return IntegerType::get(C, getPointerSizeInBits());
621 uint64_t TargetData::getIndexedOffset(const Type *ptrTy, Value* const* Indices,
622 unsigned NumIndices) const {
623 const Type *Ty = ptrTy;
624 assert(Ty->isPointerTy() && "Illegal argument for getIndexedOffset()");
627 generic_gep_type_iterator<Value* const*>
628 TI = gep_type_begin(ptrTy, Indices, Indices+NumIndices);
629 for (unsigned CurIDX = 0; CurIDX != NumIndices; ++CurIDX, ++TI) {
630 if (const StructType *STy = dyn_cast<StructType>(*TI)) {
631 assert(Indices[CurIDX]->getType() ==
632 Type::getInt32Ty(ptrTy->getContext()) &&
633 "Illegal struct idx");
634 unsigned FieldNo = cast<ConstantInt>(Indices[CurIDX])->getZExtValue();
636 // Get structure layout information...
637 const StructLayout *Layout = getStructLayout(STy);
639 // Add in the offset, as calculated by the structure layout info...
640 Result += Layout->getElementOffset(FieldNo);
642 // Update Ty to refer to current element
643 Ty = STy->getElementType(FieldNo);
645 // Update Ty to refer to current element
646 Ty = cast<SequentialType>(Ty)->getElementType();
648 // Get the array index and the size of each array element.
649 int64_t arrayIdx = cast<ConstantInt>(Indices[CurIDX])->getSExtValue();
650 Result += arrayIdx * (int64_t)getTypeAllocSize(Ty);
657 /// getPreferredAlignment - Return the preferred alignment of the specified
658 /// global. This includes an explicitly requested alignment (if the global
660 unsigned TargetData::getPreferredAlignment(const GlobalVariable *GV) const {
661 const Type *ElemType = GV->getType()->getElementType();
662 unsigned Alignment = getPrefTypeAlignment(ElemType);
663 if (GV->getAlignment() > Alignment)
664 Alignment = GV->getAlignment();
666 if (GV->hasInitializer()) {
667 if (Alignment < 16) {
668 // If the global is not external, see if it is large. If so, give it a
670 if (getTypeSizeInBits(ElemType) > 128)
671 Alignment = 16; // 16-byte alignment.
677 /// getPreferredAlignmentLog - Return the preferred alignment of the
678 /// specified global, returned in log form. This includes an explicitly
679 /// requested alignment (if the global has one).
680 unsigned TargetData::getPreferredAlignmentLog(const GlobalVariable *GV) const {
681 return Log2_32(getPreferredAlignment(GV));