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+//===--------- llvm/DataLayout.h - Data size & alignment info ---*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines layout properties related to datatype size/offset/alignment
+// information. It uses lazy annotations to cache information about how
+// structure types are laid out and used.
+//
+// This structure should be created once, filled in if the defaults are not
+// correct and then passed around by const&. None of the members functions
+// require modification to the object.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DATALAYOUT_H
+#define LLVM_DATALAYOUT_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/DataTypes.h"
+
+namespace llvm {
+
+class Value;
+class Type;
+class IntegerType;
+class StructType;
+class StructLayout;
+class GlobalVariable;
+class LLVMContext;
+template<typename T>
+class ArrayRef;
+
+/// Enum used to categorize the alignment types stored by LayoutAlignElem
+enum AlignTypeEnum {
+ INVALID_ALIGN = 0, ///< An invalid alignment
+ INTEGER_ALIGN = 'i', ///< Integer type alignment
+ VECTOR_ALIGN = 'v', ///< Vector type alignment
+ FLOAT_ALIGN = 'f', ///< Floating point type alignment
+ AGGREGATE_ALIGN = 'a', ///< Aggregate alignment
+ STACK_ALIGN = 's' ///< Stack objects alignment
+};
+
+/// Layout alignment element.
+///
+/// Stores the alignment data associated with a given alignment type (integer,
+/// vector, float) and type bit width.
+///
+/// @note The unusual order of elements in the structure attempts to reduce
+/// padding and make the structure slightly more cache friendly.
+struct LayoutAlignElem {
+ unsigned AlignType : 8; ///< Alignment type (AlignTypeEnum)
+ unsigned TypeBitWidth : 24; ///< Type bit width
+ unsigned ABIAlign : 16; ///< ABI alignment for this type/bitw
+ unsigned PrefAlign : 16; ///< Pref. alignment for this type/bitw
+
+ /// Initializer
+ static LayoutAlignElem get(AlignTypeEnum align_type, unsigned abi_align,
+ unsigned pref_align, uint32_t bit_width);
+ /// Equality predicate
+ bool operator==(const LayoutAlignElem &rhs) const;
+};
+
+/// Layout pointer alignment element.
+///
+/// Stores the alignment data associated with a given pointer and address space.
+///
+/// @note The unusual order of elements in the structure attempts to reduce
+/// padding and make the structure slightly more cache friendly.
+struct PointerAlignElem {
+ unsigned ABIAlign; ///< ABI alignment for this type/bitw
+ unsigned PrefAlign; ///< Pref. alignment for this type/bitw
+ uint32_t TypeBitWidth; ///< Type bit width
+ uint32_t AddressSpace; ///< Address space for the pointer type
+
+ /// Initializer
+ static PointerAlignElem get(uint32_t addr_space, unsigned abi_align,
+ unsigned pref_align, uint32_t bit_width);
+ /// Equality predicate
+ bool operator==(const PointerAlignElem &rhs) const;
+};
+
+
+/// DataLayout - This class holds a parsed version of the target data layout
+/// string in a module and provides methods for querying it. The target data
+/// layout string is specified *by the target* - a frontend generating LLVM IR
+/// is required to generate the right target data for the target being codegen'd
+/// to. If some measure of portability is desired, an empty string may be
+/// specified in the module.
+class DataLayout : public ImmutablePass {
+private:
+ bool LittleEndian; ///< Defaults to false
+ unsigned StackNaturalAlign; ///< Stack natural alignment
+
+ SmallVector<unsigned char, 8> LegalIntWidths; ///< Legal Integers.
+
+ /// Alignments- Where the primitive type alignment data is stored.
+ ///
+ /// @sa init().
+ /// @note Could support multiple size pointer alignments, e.g., 32-bit
+ /// pointers vs. 64-bit pointers by extending LayoutAlignment, but for now,
+ /// we don't.
+ SmallVector<LayoutAlignElem, 16> Alignments;
+ DenseMap<unsigned, PointerAlignElem> Pointers;
+
+ /// InvalidAlignmentElem - This member is a signal that a requested alignment
+ /// type and bit width were not found in the SmallVector.
+ static const LayoutAlignElem InvalidAlignmentElem;
+
+ /// InvalidPointerElem - This member is a signal that a requested pointer
+ /// type and bit width were not found in the DenseSet.
+ static const PointerAlignElem InvalidPointerElem;
+
+ // The StructType -> StructLayout map.
+ mutable void *LayoutMap;
+
+ //! Set/initialize target alignments
+ void setAlignment(AlignTypeEnum align_type, unsigned abi_align,
+ unsigned pref_align, uint32_t bit_width);
+ unsigned getAlignmentInfo(AlignTypeEnum align_type, uint32_t bit_width,
+ bool ABIAlign, Type *Ty) const;
+
+ //! Set/initialize pointer alignments
+ void setPointerAlignment(uint32_t addr_space, unsigned abi_align,
+ unsigned pref_align, uint32_t bit_width);
+
+ //! Internal helper method that returns requested alignment for type.
+ unsigned getAlignment(Type *Ty, bool abi_or_pref) const;
+
+ /// Valid alignment predicate.
+ ///
+ /// Predicate that tests a LayoutAlignElem reference returned by get() against
+ /// InvalidAlignmentElem.
+ bool validAlignment(const LayoutAlignElem &align) const {
+ return &align != &InvalidAlignmentElem;
+ }
+
+ /// Valid pointer predicate.
+ ///
+ /// Predicate that tests a PointerAlignElem reference returned by get() against
+ /// InvalidPointerElem.
+ bool validPointer(const PointerAlignElem &align) const {
+ return &align != &InvalidPointerElem;
+ }
+
+ /// Parses a target data specification string. Assert if the string is
+ /// malformed.
+ void parseSpecifier(StringRef LayoutDescription);
+
+public:
+ /// Default ctor.
+ ///
+ /// @note This has to exist, because this is a pass, but it should never be
+ /// used.
+ DataLayout();
+
+ /// Constructs a DataLayout from a specification string. See init().
+ explicit DataLayout(StringRef LayoutDescription)
+ : ImmutablePass(ID) {
+ init(LayoutDescription);
+ }
+
+ /// Initialize target data from properties stored in the module.
+ explicit DataLayout(const Module *M);
+
+ DataLayout(const DataLayout &TD) :
+ ImmutablePass(ID),
+ LittleEndian(TD.isLittleEndian()),
+ LegalIntWidths(TD.LegalIntWidths),
+ Alignments(TD.Alignments),
+ Pointers(TD.Pointers),
+ LayoutMap(0)
+ { }
+
+ ~DataLayout(); // Not virtual, do not subclass this class
+
+ /// Parse a data layout string (with fallback to default values). Ensure that
+ /// the data layout pass is registered.
+ void init(StringRef LayoutDescription);
+
+ /// Layout endianness...
+ bool isLittleEndian() const { return LittleEndian; }
+ bool isBigEndian() const { return !LittleEndian; }
+
+ /// getStringRepresentation - Return the string representation of the
+ /// DataLayout. This representation is in the same format accepted by the
+ /// string constructor above.
+ std::string getStringRepresentation() const;
+
+ /// isLegalInteger - This function returns true if the specified type is
+ /// known to be a native integer type supported by the CPU. For example,
+ /// i64 is not native on most 32-bit CPUs and i37 is not native on any known
+ /// one. This returns false if the integer width is not legal.
+ ///
+ /// The width is specified in bits.
+ ///
+ bool isLegalInteger(unsigned Width) const {
+ for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
+ if (LegalIntWidths[i] == Width)
+ return true;
+ return false;
+ }
+
+ bool isIllegalInteger(unsigned Width) const {
+ return !isLegalInteger(Width);
+ }
+
+ /// Returns true if the given alignment exceeds the natural stack alignment.
+ bool exceedsNaturalStackAlignment(unsigned Align) const {
+ return (StackNaturalAlign != 0) && (Align > StackNaturalAlign);
+ }
+
+ /// fitsInLegalInteger - This function returns true if the specified type fits
+ /// in a native integer type supported by the CPU. For example, if the CPU
+ /// only supports i32 as a native integer type, then i27 fits in a legal
+ // integer type but i45 does not.
+ bool fitsInLegalInteger(unsigned Width) const {
+ for (unsigned i = 0, e = (unsigned)LegalIntWidths.size(); i != e; ++i)
+ if (Width <= LegalIntWidths[i])
+ return true;
+ return false;
+ }
+
+ /// Layout pointer alignment
+ /// FIXME: The defaults need to be removed once all of
+ /// the backends/clients are updated.
+ unsigned getPointerABIAlignment(unsigned AS = 0) const {
+ DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
+ if (val == Pointers.end()) {
+ val = Pointers.find(0);
+ }
+ return val->second.ABIAlign;
+ }
+ /// Return target's alignment for stack-based pointers
+ /// FIXME: The defaults need to be removed once all of
+ /// the backends/clients are updated.
+ unsigned getPointerPrefAlignment(unsigned AS = 0) const {
+ DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
+ if (val == Pointers.end()) {
+ val = Pointers.find(0);
+ }
+ return val->second.PrefAlign;
+ }
+ /// Layout pointer size
+ /// FIXME: The defaults need to be removed once all of
+ /// the backends/clients are updated.
+ unsigned getPointerSize(unsigned AS = 0) const {
+ DenseMap<unsigned, PointerAlignElem>::const_iterator val = Pointers.find(AS);
+ if (val == Pointers.end()) {
+ val = Pointers.find(0);
+ }
+ return val->second.TypeBitWidth;
+ }
+ /// Layout pointer size, in bits
+ /// FIXME: The defaults need to be removed once all of
+ /// the backends/clients are updated.
+ unsigned getPointerSizeInBits(unsigned AS = 0) const {
+ return getPointerSize(AS) * 8;
+ }
+ /// Size examples:
+ ///
+ /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*]
+ /// ---- ---------- --------------- ---------------
+ /// i1 1 8 8
+ /// i8 8 8 8
+ /// i19 19 24 32
+ /// i32 32 32 32
+ /// i100 100 104 128
+ /// i128 128 128 128
+ /// Float 32 32 32
+ /// Double 64 64 64
+ /// X86_FP80 80 80 96
+ ///
+ /// [*] The alloc size depends on the alignment, and thus on the target.
+ /// These values are for x86-32 linux.
+
+ /// getTypeSizeInBits - Return the number of bits necessary to hold the
+ /// specified type. For example, returns 36 for i36 and 80 for x86_fp80.
+ /// The type passed must have a size (Type::isSized() must return true).
+ uint64_t getTypeSizeInBits(Type* Ty) const;
+
+ /// getTypeStoreSize - Return the maximum number of bytes that may be
+ /// overwritten by storing the specified type. For example, returns 5
+ /// for i36 and 10 for x86_fp80.
+ uint64_t getTypeStoreSize(Type *Ty) const {
+ return (getTypeSizeInBits(Ty)+7)/8;
+ }
+
+ /// getTypeStoreSizeInBits - Return the maximum number of bits that may be
+ /// overwritten by storing the specified type; always a multiple of 8. For
+ /// example, returns 40 for i36 and 80 for x86_fp80.
+ uint64_t getTypeStoreSizeInBits(Type *Ty) const {
+ return 8*getTypeStoreSize(Ty);
+ }
+
+ /// getTypeAllocSize - Return the offset in bytes between successive objects
+ /// of the specified type, including alignment padding. This is the amount
+ /// that alloca reserves for this type. For example, returns 12 or 16 for
+ /// x86_fp80, depending on alignment.
+ uint64_t getTypeAllocSize(Type* Ty) const {
+ // Round up to the next alignment boundary.
+ return RoundUpAlignment(getTypeStoreSize(Ty), getABITypeAlignment(Ty));
+ }
+
+ /// getTypeAllocSizeInBits - Return the offset in bits between successive
+ /// objects of the specified type, including alignment padding; always a
+ /// multiple of 8. This is the amount that alloca reserves for this type.
+ /// For example, returns 96 or 128 for x86_fp80, depending on alignment.
+ uint64_t getTypeAllocSizeInBits(Type* Ty) const {
+ return 8*getTypeAllocSize(Ty);
+ }
+
+ /// getABITypeAlignment - Return the minimum ABI-required alignment for the
+ /// specified type.
+ unsigned getABITypeAlignment(Type *Ty) const;
+
+ /// getABIIntegerTypeAlignment - Return the minimum ABI-required alignment for
+ /// an integer type of the specified bitwidth.
+ unsigned getABIIntegerTypeAlignment(unsigned BitWidth) const;
+
+
+ /// getCallFrameTypeAlignment - Return the minimum ABI-required alignment
+ /// for the specified type when it is part of a call frame.
+ unsigned getCallFrameTypeAlignment(Type *Ty) const;
+
+
+ /// getPrefTypeAlignment - Return the preferred stack/global alignment for
+ /// the specified type. This is always at least as good as the ABI alignment.
+ unsigned getPrefTypeAlignment(Type *Ty) const;
+
+ /// getPreferredTypeAlignmentShift - Return the preferred alignment for the
+ /// specified type, returned as log2 of the value (a shift amount).
+ ///
+ unsigned getPreferredTypeAlignmentShift(Type *Ty) const;
+
+ /// getIntPtrType - Return an integer type with size at least as big as that
+ /// of a pointer in the given address space.
+ IntegerType *getIntPtrType(LLVMContext &C, unsigned AddressSpace = 0) const;
+
+ /// getIntPtrType - Return an integer (vector of integer) type with size at
+ /// least as big as that of a pointer of the given pointer (vector of pointer)
+ /// type.
+ Type *getIntPtrType(Type *) const;
+
+ /// getIndexedOffset - return the offset from the beginning of the type for
+ /// the specified indices. This is used to implement getelementptr.
+ ///
+ uint64_t getIndexedOffset(Type *Ty, ArrayRef<Value *> Indices) const;
+
+ /// getStructLayout - Return a StructLayout object, indicating the alignment
+ /// of the struct, its size, and the offsets of its fields. Note that this
+ /// information is lazily cached.
+ const StructLayout *getStructLayout(StructType *Ty) const;
+
+ /// getPreferredAlignment - Return the preferred alignment of the specified
+ /// global. This includes an explicitly requested alignment (if the global
+ /// has one).
+ unsigned getPreferredAlignment(const GlobalVariable *GV) const;
+
+ /// getPreferredAlignmentLog - Return the preferred alignment of the
+ /// specified global, returned in log form. This includes an explicitly
+ /// requested alignment (if the global has one).
+ unsigned getPreferredAlignmentLog(const GlobalVariable *GV) const;
+
+ /// RoundUpAlignment - Round the specified value up to the next alignment
+ /// boundary specified by Alignment. For example, 7 rounded up to an
+ /// alignment boundary of 4 is 8. 8 rounded up to the alignment boundary of 4
+ /// is 8 because it is already aligned.
+ template <typename UIntTy>
+ static UIntTy RoundUpAlignment(UIntTy Val, unsigned Alignment) {
+ assert((Alignment & (Alignment-1)) == 0 && "Alignment must be power of 2!");
+ return (Val + (Alignment-1)) & ~UIntTy(Alignment-1);
+ }
+
+ static char ID; // Pass identification, replacement for typeid
+};
+
+/// StructLayout - used to lazily calculate structure layout information for a
+/// target machine, based on the DataLayout structure.
+///
+class StructLayout {
+ uint64_t StructSize;
+ unsigned StructAlignment;
+ unsigned NumElements;
+ uint64_t MemberOffsets[1]; // variable sized array!
+public:
+
+ uint64_t getSizeInBytes() const {
+ return StructSize;
+ }
+
+ uint64_t getSizeInBits() const {
+ return 8*StructSize;
+ }
+
+ unsigned getAlignment() const {
+ return StructAlignment;
+ }
+
+ /// getElementContainingOffset - Given a valid byte offset into the structure,
+ /// return the structure index that contains it.
+ ///
+ unsigned getElementContainingOffset(uint64_t Offset) const;
+
+ uint64_t getElementOffset(unsigned Idx) const {
+ assert(Idx < NumElements && "Invalid element idx!");
+ return MemberOffsets[Idx];
+ }
+
+ uint64_t getElementOffsetInBits(unsigned Idx) const {
+ return getElementOffset(Idx)*8;
+ }
+
+private:
+ friend class DataLayout; // Only DataLayout can create this class
+ StructLayout(StructType *ST, const DataLayout &TD);
+};
+
+} // End llvm namespace
+
+#endif
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