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3a3465b71d
optimizations when emitting calls to the function; instead those calls may use faster relocations which require the function to be immediately resolved upon loading the dynamic object featuring the call. This is useful when it is known that the function will be called frequently and pervasively and therefore there is no merit in delaying binding of the function. Currently only implemented for x86-64, where it turns into a call through the global offset table. Patch by Dan Gohman, who assures me that he's going to add LangRef documentation for this once it's committed. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133080 91177308-0d34-0410-b5e6-96231b3b80d8
308 lines
12 KiB
C++
308 lines
12 KiB
C++
//===-- llvm/Attributes.h - Container for Attributes ------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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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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//===----------------------------------------------------------------------===//
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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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//===----------------------------------------------------------------------===//
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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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#include <cassert>
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#include <string>
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namespace llvm {
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class Type;
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/// Attributes - A bitset of attributes.
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typedef unsigned Attributes;
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namespace Attribute {
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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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/// instructions.
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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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///desirable
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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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///alignstack(1))
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const Attributes Hotpatch = 1<<29; ///< Function should have special
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///'hotpatch' sequence in prologue
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const Attributes UWTable = 1<<30; ///< Function must be in a unwind
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///table
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const Attributes NonLazyBind = 1U<<31; ///< Function is called early and/or
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/// often, so lazy binding isn't
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/// worthwhile.
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/// Note that uwtable is about the ABI or the user mandating an entry in the
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/// unwind table. The nounwind attribute is about an exception passing by the
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/// function.
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/// In a theoretical system that uses tables for profiling and sjlj for
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/// exceptions, they would be fully independent. In a normal system that
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/// uses tables for both, the semantics are:
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/// nil = Needs an entry because an exception might pass by.
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/// nounwind = No need for an entry
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/// uwtable = Needs an entry because the ABI says so and because
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/// an exception might pass by.
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/// uwtable + nounwind = Needs an entry because the ABI says so.
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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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Hotpatch | UWTable | NonLazyBind;
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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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ZExt | SExt,
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ReadNone | ReadOnly,
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NoInline | AlwaysInline
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};
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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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if (i == 0)
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return 0;
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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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}
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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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if (Align == 0)
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return 0;
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return 1U << ((Align >> 16) - 1);
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}
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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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if (i == 0)
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return 0;
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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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}
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/// This returns the stack alignment field of an attribute as a byte alignment
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/// value.
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inline unsigned getStackAlignmentFromAttrs(Attributes A) {
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Attributes StackAlign = A & Attribute::StackAlignment;
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if (StackAlign == 0)
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return 0;
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return 1U << ((StackAlign >> 26) - 1);
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}
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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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/// with an index.
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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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P.Index = Idx;
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P.Attrs = Attrs;
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return P;
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}
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};
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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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class AttrListPtr {
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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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public:
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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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~AttrListPtr();
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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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}
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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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/// returned.
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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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}
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/// getRetAttributes - The attributes for the ret value are
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/// returned.
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Attributes getRetAttributes() const {
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return getAttributes(0);
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}
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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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}
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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) != 0;
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}
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/// getParamAlignment - Return the alignment for the specified function
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/// parameter.
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unsigned getParamAlignment(unsigned Idx) const {
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return Attribute::getAlignmentFromAttrs(getAttributes(Idx));
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}
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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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void dump() const;
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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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/// attribute list.
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void *getRawPointer() const {
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return AttrList;
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}
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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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///
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bool isEmpty() const {
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return AttrList == 0;
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}
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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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private:
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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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};
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} // End llvm namespace
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#endif
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