include/llvm/Attributes.h

   1 //===-- llvm/Attributes.h - Container for Attributes ------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file contains the simple types necessary to represent the
  11 // attributes associated with functions and their calls.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_ATTRIBUTES_H
  16 #define LLVM_ATTRIBUTES_H
  17
  18 #include "llvm/Support/MathExtras.h"
  19 #include <cassert>
  20 #include <string>
  21
  22 namespace llvm {
  23 class Type;
  24
  25 /// Attributes - A bitset of attributes.
  26 typedef unsigned Attributes;
  27
  28 namespace Attribute {
  29
  30 /// Function parameters and results can have attributes to indicate how they
  31 /// should be treated by optimizations and code generation. This enumeration
  32 /// lists the attributes that can be associated with parameters, function
  33 /// results or the function itself.
  34 /// @brief Function attributes.
  35
  36 const Attributes None      = 0;     ///< No attributes have been set
  37 const Attributes ZExt      = 1<<0;  ///< Zero extended before/after call
  38 const Attributes SExt      = 1<<1;  ///< Sign extended before/after call
  39 const Attributes NoReturn  = 1<<2;  ///< Mark the function as not returning
  40 const Attributes InReg     = 1<<3;  ///< Force argument to be passed in register
  41 const Attributes StructRet = 1<<4;  ///< Hidden pointer to structure to return
  42 const Attributes NoUnwind  = 1<<5;  ///< Function doesn't unwind stack
  43 const Attributes NoAlias   = 1<<6;  ///< Considered to not alias after call
  44 const Attributes ByVal     = 1<<7;  ///< Pass structure by value
  45 const Attributes Nest      = 1<<8;  ///< Nested function static chain
  46 const Attributes ReadNone  = 1<<9;  ///< Function does not access memory
  47 const Attributes ReadOnly  = 1<<10; ///< Function only reads from memory
  48 const Attributes NoInline        = 1<<11; ///< inline=never
  49 const Attributes AlwaysInline    = 1<<12; ///< inline=always
  50 const Attributes OptimizeForSize = 1<<13; ///< opt_size
  51 const Attributes StackProtect    = 1<<14; ///< Stack protection.
  52 const Attributes StackProtectReq = 1<<15; ///< Stack protection required.
  53 const Attributes Alignment = 31<<16; ///< Alignment of parameter (5 bits)
  54                                      // stored as log2 of alignment with +1 bias
  55                                      // 0 means unaligned different from align 1
  56 const Attributes NoCapture = 1<<21; ///< Function creates no aliases of pointer
  57 const Attributes NoRedZone = 1<<22; /// disable redzone
  58 const Attributes NoImplicitFloat = 1<<23; /// disable implicit floating point
  59                                           /// instructions.
  60 const Attributes Naked           = 1<<24; ///< Naked function
  61 const Attributes InlineHint      = 1<<25; ///< source said inlining was
  62                                           ///desirable
  63 const Attributes StackAlignment  = 7<<26; ///< Alignment of stack for
  64                                           ///function (3 bits) stored as log2
  65                                           ///of alignment with +1 bias
  66                                           ///0 means unaligned (different from
  67                                           ///alignstack(1))
  68 const Attributes Hotpatch    = 1<<29;     ///< Function should have special
  69                                           ///'hotpatch' sequence in prologue
  70
  71 /// @brief Attributes that only apply to function parameters.
  72 const Attributes ParameterOnly = ByVal | Nest | StructRet | NoCapture;
  73
  74 /// @brief Attributes that may be applied to the function itself.  These cannot
  75 /// be used on return values or function parameters.
  76 const Attributes FunctionOnly = NoReturn | NoUnwind | ReadNone | ReadOnly |
  77   NoInline | AlwaysInline | OptimizeForSize | StackProtect | StackProtectReq |
  78   NoRedZone | NoImplicitFloat | Naked | InlineHint | StackAlignment |
  79   Hotpatch;
  80
  81 /// @brief Parameter attributes that do not apply to vararg call arguments.
  82 const Attributes VarArgsIncompatible = StructRet;
  83
  84 /// @brief Attributes that are mutually incompatible.
  85 const Attributes MutuallyIncompatible[4] = {
  86   ByVal | InReg | Nest | StructRet,
  87   ZExt  | SExt,
  88   ReadNone | ReadOnly,
  89   NoInline | AlwaysInline
  90 };
  91
  92 /// @brief Which attributes cannot be applied to a type.
  93 Attributes typeIncompatible(const Type *Ty);
  94
  95 /// This turns an int alignment (a power of 2, normally) into the
  96 /// form used internally in Attributes.
  97 inline Attributes constructAlignmentFromInt(unsigned i) {
  98   // Default alignment, allow the target to define how to align it.
  99   if (i == 0)
 100     return 0;
 101
 102   assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
 103   assert(i <= 0x40000000 && "Alignment too large.");
 104   return (Log2_32(i)+1) << 16;
 105 }
 106
 107 /// This returns the alignment field of an attribute as a byte alignment value.
 108 inline unsigned getAlignmentFromAttrs(Attributes A) {
 109   Attributes Align = A & Attribute::Alignment;
 110   if (Align == 0)
 111     return 0;
 112
 113   return 1U << ((Align >> 16) - 1);
 114 }
 115
 116 /// This turns an int stack alignment (which must be a power of 2) into
 117 /// the form used internally in Attributes.
 118 inline Attributes constructStackAlignmentFromInt(unsigned i) {
 119   // Default alignment, allow the target to define how to align it.
 120   if (i == 0)
 121     return 0;
 122
 123   assert(isPowerOf2_32(i) && "Alignment must be a power of two.");
 124   assert(i <= 0x100 && "Alignment too large.");
 125   return (Log2_32(i)+1) << 26;
 126 }
 127
 128 /// This returns the stack alignment field of an attribute as a byte alignment
 129 /// value.
 130 inline unsigned getStackAlignmentFromAttrs(Attributes A) {
 131   Attributes StackAlign = A & Attribute::StackAlignment;
 132   if (StackAlign == 0)
 133     return 0;
 134
 135   return 1U << ((StackAlign >> 26) - 1);
 136 }
 137
 138
 139 /// The set of Attributes set in Attributes is converted to a
 140 /// string of equivalent mnemonics. This is, presumably, for writing out
 141 /// the mnemonics for the assembly writer.
 142 /// @brief Convert attribute bits to text
 143 std::string getAsString(Attributes Attrs);
 144 } // end namespace Attribute
 145
 146 /// This is just a pair of values to associate a set of attributes
 147 /// with an index.
 148 struct AttributeWithIndex {
 149   Attributes Attrs; ///< The attributes that are set, or'd together.
 150   unsigned Index; ///< Index of the parameter for which the attributes apply.
 151                   ///< Index 0 is used for return value attributes.
 152                   ///< Index ~0U is used for function attributes.
 153
 154   static AttributeWithIndex get(unsigned Idx, Attributes Attrs) {
 155     AttributeWithIndex P;
 156     P.Index = Idx;
 157     P.Attrs = Attrs;
 158     return P;
 159   }
 160 };
 161
 162 //===----------------------------------------------------------------------===//
 163 // AttrListPtr Smart Pointer
 164 //===----------------------------------------------------------------------===//
 165
 166 class AttributeListImpl;
 167
 168 /// AttrListPtr - This class manages the ref count for the opaque
 169 /// AttributeListImpl object and provides accessors for it.
 170 class AttrListPtr {
 171   /// AttrList - The attributes that we are managing.  This can be null
 172   /// to represent the empty attributes list.
 173   AttributeListImpl *AttrList;
 174 public:
 175   AttrListPtr() : AttrList(0) {}
 176   AttrListPtr(const AttrListPtr &P);
 177   const AttrListPtr &operator=(const AttrListPtr &RHS);
 178   ~AttrListPtr();
 179
 180   //===--------------------------------------------------------------------===//
 181   // Attribute List Construction and Mutation
 182   //===--------------------------------------------------------------------===//
 183
 184   /// get - Return a Attributes list with the specified parameter in it.
 185   static AttrListPtr get(const AttributeWithIndex *Attr, unsigned NumAttrs);
 186
 187   /// get - Return a Attribute list with the parameters specified by the
 188   /// consecutive random access iterator range.
 189   template <typename Iter>
 190   static AttrListPtr get(const Iter &I, const Iter &E) {
 191     if (I == E) return AttrListPtr();  // Empty list.
 192     return get(&*I, static_cast<unsigned>(E-I));
 193   }
 194
 195   /// addAttr - Add the specified attribute at the specified index to this
 196   /// attribute list.  Since attribute lists are immutable, this
 197   /// returns the new list.
 198   AttrListPtr addAttr(unsigned Idx, Attributes Attrs) const;
 199
 200   /// removeAttr - Remove the specified attribute at the specified index from
 201   /// this attribute list.  Since attribute lists are immutable, this
 202   /// returns the new list.
 203   AttrListPtr removeAttr(unsigned Idx, Attributes Attrs) const;
 204
 205   //===--------------------------------------------------------------------===//
 206   // Attribute List Accessors
 207   //===--------------------------------------------------------------------===//
 208   /// getParamAttributes - The attributes for the specified index are
 209   /// returned.
 210   Attributes getParamAttributes(unsigned Idx) const {
 211     assert (Idx && Idx != ~0U && "Invalid parameter index!");
 212     return getAttributes(Idx);
 213   }
 214
 215   /// getRetAttributes - The attributes for the ret value are
 216   /// returned.
 217   Attributes getRetAttributes() const {
 218     return getAttributes(0);
 219   }
 220
 221   /// getFnAttributes - The function attributes are returned.
 222   Attributes getFnAttributes() const {
 223     return getAttributes(~0U);
 224   }
 225
 226   /// paramHasAttr - Return true if the specified parameter index has the
 227   /// specified attribute set.
 228   bool paramHasAttr(unsigned Idx, Attributes Attr) const {
 229     return (getAttributes(Idx) & Attr) != 0;
 230   }
 231
 232   /// getParamAlignment - Return the alignment for the specified function
 233   /// parameter.
 234   unsigned getParamAlignment(unsigned Idx) const {
 235     return Attribute::getAlignmentFromAttrs(getAttributes(Idx));
 236   }
 237
 238   /// hasAttrSomewhere - Return true if the specified attribute is set for at
 239   /// least one parameter or for the return value.
 240   bool hasAttrSomewhere(Attributes Attr) const;
 241
 242   /// operator==/!= - Provide equality predicates.
 243   bool operator==(const AttrListPtr &RHS) const
 244   { return AttrList == RHS.AttrList; }
 245   bool operator!=(const AttrListPtr &RHS) const
 246   { return AttrList != RHS.AttrList; }
 247
 248   void dump() const;
 249
 250   //===--------------------------------------------------------------------===//
 251   // Attribute List Introspection
 252   //===--------------------------------------------------------------------===//
 253
 254   /// getRawPointer - Return a raw pointer that uniquely identifies this
 255   /// attribute list.
 256   void *getRawPointer() const {
 257     return AttrList;
 258   }
 259
 260   // Attributes are stored as a dense set of slots, where there is one
 261   // slot for each argument that has an attribute.  This allows walking over the
 262   // dense set instead of walking the sparse list of attributes.
 263
 264   /// isEmpty - Return true if there are no attributes.
 265   ///
 266   bool isEmpty() const {
 267     return AttrList == 0;
 268   }
 269
 270   /// getNumSlots - Return the number of slots used in this attribute list.
 271   /// This is the number of arguments that have an attribute set on them
 272   /// (including the function itself).
 273   unsigned getNumSlots() const;
 274
 275   /// getSlot - Return the AttributeWithIndex at the specified slot.  This
 276   /// holds a index number plus a set of attributes.
 277   const AttributeWithIndex &getSlot(unsigned Slot) const;
 278
 279 private:
 280   explicit AttrListPtr(AttributeListImpl *L);
 281
 282   /// getAttributes - The attributes for the specified index are
 283   /// returned.  Attributes for the result are denoted with Idx = 0.
 284   Attributes getAttributes(unsigned Idx) const;
 285
 286 };
 287
 288 } // End llvm namespace
 289
 290 #endif