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//===-- llvm/Attributes.h - Container for Attributes ------------*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file contains the simple types necessary to represent the
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// attributes associated with functions and their calls.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ATTRIBUTES_H
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#define LLVM_ATTRIBUTES_H
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#include "llvm/Support/MathExtras.h"
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/// Attributes - A bitset of attributes.
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typedef unsigned Attributes;
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/// Function parameters and results can have attributes to indicate how they
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/// should be treated by optimizations and code generation. This enumeration
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/// lists the attributes that can be associated with parameters, function
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/// results or the function itself.
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/// @brief Function attributes.
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const Attributes None = 0; ///< No attributes have been set
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const Attributes ZExt = 1<<0; ///< Zero extended before/after call
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const Attributes SExt = 1<<1; ///< Sign extended before/after call
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const Attributes NoReturn = 1<<2; ///< Mark the function as not returning
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const Attributes InReg = 1<<3; ///< Force argument to be passed in register
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const Attributes StructRet = 1<<4; ///< Hidden pointer to structure to return
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const Attributes NoUnwind = 1<<5; ///< Function doesn't unwind stack
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const Attributes NoAlias = 1<<6; ///< Considered to not alias after call
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const Attributes ByVal = 1<<7; ///< Pass structure by value
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const Attributes Nest = 1<<8; ///< Nested function static chain
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const Attributes ReadNone = 1<<9; ///< Function does not access memory
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const Attributes ReadOnly = 1<<10; ///< Function only reads from memory
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const Attributes NoInline = 1<<11; ///< inline=never
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const Attributes AlwaysInline = 1<<12; ///< inline=always
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const Attributes OptimizeForSize = 1<<13; ///< opt_size
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const Attributes StackProtect = 1<<14; ///< Stack protection.
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const Attributes StackProtectReq = 1<<15; ///< Stack protection required.
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const Attributes Alignment = 31<<16; ///< Alignment of parameter (5 bits)
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// stored as log2 of alignment with +1 bias
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// 0 means unaligned different from align 1
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const Attributes NoCapture = 1<<21; ///< Function creates no aliases of pointer
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const Attributes NoRedZone = 1<<22; /// disable redzone
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const Attributes NoImplicitFloat = 1<<23; /// disable implicit floating point
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const Attributes Naked = 1<<24; ///< Naked function
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const Attributes InlineHint = 1<<25; ///< source said inlining was
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const Attributes StackAlignment = 7<<26; ///< Alignment of stack for
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///function (3 bits) stored as log2
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///of alignment with +1 bias
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///0 means unaligned (different from
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/// @brief Attributes that only apply to function parameters.
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const Attributes ParameterOnly = ByVal | Nest | StructRet | NoCapture;
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/// @brief Attributes that may be applied to the function itself. These cannot
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/// be used on return values or function parameters.
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const Attributes FunctionOnly = NoReturn | NoUnwind | ReadNone | ReadOnly |
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NoInline | AlwaysInline | OptimizeForSize | StackProtect | StackProtectReq |
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NoRedZone | NoImplicitFloat | Naked | InlineHint | StackAlignment;
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/// @brief Parameter attributes that do not apply to vararg call arguments.
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const Attributes VarArgsIncompatible = StructRet;
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/// @brief Attributes that are mutually incompatible.
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const Attributes MutuallyIncompatible[4] = {
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ByVal | InReg | Nest | StructRet,
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NoInline | AlwaysInline
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/// @brief Which attributes cannot be applied to a type.
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Attributes typeIncompatible(const Type *Ty);
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/// This turns an int alignment (a power of 2, normally) into the
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/// form used internally in Attributes.
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inline Attributes constructAlignmentFromInt(unsigned i) {
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// Default alignment, allow the target to define how to align it.
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assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
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assert(i <= 0x40000000 && "Alignment too large.");
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return (Log2_32(i)+1) << 16;
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/// This returns the alignment field of an attribute as a byte alignment value.
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inline unsigned getAlignmentFromAttrs(Attributes A) {
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Attributes Align = A & Attribute::Alignment;
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return 1U << ((Align >> 16) - 1);
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/// This turns an int stack alignment (which must be a power of 2) into
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/// the form used internally in Attributes.
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inline Attributes constructStackAlignmentFromInt(unsigned i) {
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// Default alignment, allow the target to define how to align it.
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assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
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assert(i <= 0x100 && "Alignment too large.");
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return (Log2_32(i)+1) << 26;
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/// This returns the stack alignment field of an attribute as a byte alignment
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inline unsigned getStackAlignmentFromAttrs(Attributes A) {
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Attributes StackAlign = A & Attribute::StackAlignment;
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return 1U << ((StackAlign >> 26) - 1);
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/// The set of Attributes set in Attributes is converted to a
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/// string of equivalent mnemonics. This is, presumably, for writing out
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/// the mnemonics for the assembly writer.
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/// @brief Convert attribute bits to text
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std::string getAsString(Attributes Attrs);
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} // end namespace Attribute
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/// This is just a pair of values to associate a set of attributes
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struct AttributeWithIndex {
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Attributes Attrs; ///< The attributes that are set, or'd together.
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unsigned Index; ///< Index of the parameter for which the attributes apply.
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///< Index 0 is used for return value attributes.
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///< Index ~0U is used for function attributes.
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static AttributeWithIndex get(unsigned Idx, Attributes Attrs) {
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AttributeWithIndex P;
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//===----------------------------------------------------------------------===//
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// AttrListPtr Smart Pointer
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//===----------------------------------------------------------------------===//
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class AttributeListImpl;
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/// AttrListPtr - This class manages the ref count for the opaque
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/// AttributeListImpl object and provides accessors for it.
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/// AttrList - The attributes that we are managing. This can be null
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/// to represent the empty attributes list.
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AttributeListImpl *AttrList;
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AttrListPtr() : AttrList(0) {}
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AttrListPtr(const AttrListPtr &P);
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const AttrListPtr &operator=(const AttrListPtr &RHS);
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//===--------------------------------------------------------------------===//
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// Attribute List Construction and Mutation
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//===--------------------------------------------------------------------===//
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/// get - Return a Attributes list with the specified parameter in it.
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static AttrListPtr get(const AttributeWithIndex *Attr, unsigned NumAttrs);
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/// get - Return a Attribute list with the parameters specified by the
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/// consecutive random access iterator range.
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template <typename Iter>
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static AttrListPtr get(const Iter &I, const Iter &E) {
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if (I == E) return AttrListPtr(); // Empty list.
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return get(&*I, static_cast<unsigned>(E-I));
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/// addAttr - Add the specified attribute at the specified index to this
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/// attribute list. Since attribute lists are immutable, this
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/// returns the new list.
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AttrListPtr addAttr(unsigned Idx, Attributes Attrs) const;
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/// removeAttr - Remove the specified attribute at the specified index from
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/// this attribute list. Since attribute lists are immutable, this
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/// returns the new list.
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AttrListPtr removeAttr(unsigned Idx, Attributes Attrs) const;
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//===--------------------------------------------------------------------===//
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// Attribute List Accessors
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//===--------------------------------------------------------------------===//
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/// getParamAttributes - The attributes for the specified index are
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Attributes getParamAttributes(unsigned Idx) const {
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assert (Idx && Idx != ~0U && "Invalid parameter index!");
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return getAttributes(Idx);
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/// getRetAttributes - The attributes for the ret value are
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Attributes getRetAttributes() const {
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return getAttributes(0);
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/// getFnAttributes - The function attributes are returned.
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Attributes getFnAttributes() const {
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return getAttributes(~0U);
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/// paramHasAttr - Return true if the specified parameter index has the
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/// specified attribute set.
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bool paramHasAttr(unsigned Idx, Attributes Attr) const {
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return getAttributes(Idx) & Attr;
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/// getParamAlignment - Return the alignment for the specified function
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unsigned getParamAlignment(unsigned Idx) const {
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return Attribute::getAlignmentFromAttrs(getAttributes(Idx));
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/// hasAttrSomewhere - Return true if the specified attribute is set for at
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/// least one parameter or for the return value.
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bool hasAttrSomewhere(Attributes Attr) const;
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/// operator==/!= - Provide equality predicates.
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bool operator==(const AttrListPtr &RHS) const
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{ return AttrList == RHS.AttrList; }
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bool operator!=(const AttrListPtr &RHS) const
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{ return AttrList != RHS.AttrList; }
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//===--------------------------------------------------------------------===//
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// Attribute List Introspection
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//===--------------------------------------------------------------------===//
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/// getRawPointer - Return a raw pointer that uniquely identifies this
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void *getRawPointer() const {
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// Attributes are stored as a dense set of slots, where there is one
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// slot for each argument that has an attribute. This allows walking over the
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// dense set instead of walking the sparse list of attributes.
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/// isEmpty - Return true if there are no attributes.
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bool isEmpty() const {
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return AttrList == 0;
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/// getNumSlots - Return the number of slots used in this attribute list.
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/// This is the number of arguments that have an attribute set on them
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/// (including the function itself).
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unsigned getNumSlots() const;
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/// getSlot - Return the AttributeWithIndex at the specified slot. This
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/// holds a index number plus a set of attributes.
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const AttributeWithIndex &getSlot(unsigned Slot) const;
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explicit AttrListPtr(AttributeListImpl *L);
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/// getAttributes - The attributes for the specified index are
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/// returned. Attributes for the result are denoted with Idx = 0.
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Attributes getAttributes(unsigned Idx) const;
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} // End llvm namespace