Attributes.h revision 19c874638d9478a5d5028854817a5ee72293bb2b 
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 <string>
19
20namespace llvm {
21class Type;
22
23/// Attributes - A bitset of attributes.
24typedef unsigned Attributes;
25
26namespace Attribute {
27
28/// Function parameters and results can have attributes to indicate how they
29/// should be treated by optimizations and code generation. This enumeration
30/// lists the attributes that can be associated with parameters, function
31/// results or the function itself.
32/// @brief Function attributes.
33
34const Attributes None      = 0;     ///< No attributes have been set
35const Attributes ZExt      = 1<<0;  ///< Zero extended before/after call
36const Attributes SExt      = 1<<1;  ///< Sign extended before/after call
37const Attributes NoReturn  = 1<<2;  ///< Mark the function as not returning
38const Attributes InReg     = 1<<3;  ///< Force argument to be passed in register
39const Attributes StructRet = 1<<4;  ///< Hidden pointer to structure to return
40const Attributes NoUnwind  = 1<<5;  ///< Function doesn't unwind stack
41const Attributes NoAlias   = 1<<6;  ///< Considered to not alias after call
42const Attributes ByVal     = 1<<7;  ///< Pass structure by value
43const Attributes Nest      = 1<<8;  ///< Nested function static chain
44const Attributes ReadNone  = 1<<9;  ///< Function does not access memory
45const Attributes ReadOnly  = 1<<10; ///< Function only reads from memory
46const Attributes NoInline        = 1<<11; // inline=never
47const Attributes AlwaysInline    = 1<<12; // inline=always
48const Attributes OptimizeForSize = 1<<13; // opt_size
49const Attributes Alignment = 0xffff<<16; ///< Alignment of parameter (16 bits)
50                                    // 0 = unknown, else in clear (not log)
51
52/// @brief Attributes that only apply to function parameters.
53const Attributes ParameterOnly = ByVal | Nest | StructRet;
54
55/// @brief Attributes that only apply to function return values.
56const Attributes ReturnOnly = NoReturn | NoUnwind | ReadNone | ReadOnly;
57
58/// @brief Parameter attributes that do not apply to vararg call arguments.
59const Attributes VarArgsIncompatible = StructRet;
60
61/// @brief Attributes that are mutually incompatible.
62const Attributes MutuallyIncompatible[3] = {
63  ByVal | InReg | Nest  | StructRet,
64  ZExt  | SExt,
65  ReadNone | ReadOnly
66};
67
68/// @brief Which attributes cannot be applied to a type.
69Attributes typeIncompatible(const Type *Ty);
70
71/// This turns an int alignment (a power of 2, normally) into the
72/// form used internally in Attributes.
73inline Attributes constructAlignmentFromInt(unsigned i) {
74  return (i << 16);
75}
76
77/// The set of Attributes set in Attributes is converted to a
78/// string of equivalent mnemonics. This is, presumably, for writing out
79/// the mnemonics for the assembly writer.
80/// @brief Convert attribute bits to text
81std::string getAsString(Attributes Attrs);
82} // end namespace Attribute
83
84namespace Attribute {
85} // end namespace Attribute
86
87/// This is just a pair of values to associate a set of attributes
88/// with an index.
89struct AttributeWithIndex {
90  Attributes Attrs; ///< The attributes that are set, or'd together.
91  unsigned Index; ///< Index of the parameter for which the attributes apply.
92                  ///< Index 0 is used for return value attributes.
93                  ///< Index ~0U is used for function attributes.
94
95  static AttributeWithIndex get(unsigned Idx, Attributes Attrs) {
96    AttributeWithIndex P;
97    P.Index = Idx;
98    P.Attrs = Attrs;
99    return P;
100  }
101};
102
103//===----------------------------------------------------------------------===//
104// AttrListPtr Smart Pointer
105//===----------------------------------------------------------------------===//
106
107class AttributeListImpl;
108
109/// AttrListPtr - This class manages the ref count for the opaque
110/// AttributeListImpl object and provides accessors for it.
111class AttrListPtr {
112  /// AttrList - The attributes that we are managing.  This can be null
113  /// to represent the empty attributes list.
114  AttributeListImpl *AttrList;
115public:
116  AttrListPtr() : AttrList(0) {}
117  AttrListPtr(const AttrListPtr &P);
118  const AttrListPtr &operator=(const AttrListPtr &RHS);
119  ~AttrListPtr();
120
121  //===--------------------------------------------------------------------===//
122  // Attribute List Construction and Mutation
123  //===--------------------------------------------------------------------===//
124
125  /// get - Return a Attributes list with the specified parameter in it.
126  static AttrListPtr get(const AttributeWithIndex *Attr, unsigned NumAttrs);
127
128  /// get - Return a Attribute list with the parameters specified by the
129  /// consecutive random access iterator range.
130  template <typename Iter>
131  static AttrListPtr get(const Iter &I, const Iter &E) {
132    if (I == E) return AttrListPtr();  // Empty list.
133    return get(&*I, static_cast<unsigned>(E-I));
134  }
135
136  /// addAttr - Add the specified attribute at the specified index to this
137  /// attribute list.  Since attribute lists are immutable, this
138  /// returns the new list.
139  AttrListPtr addAttr(unsigned Idx, Attributes Attrs) const;
140
141  /// removeAttr - Remove the specified attribute at the specified index from
142  /// this attribute list.  Since attribute lists are immutable, this
143  /// returns the new list.
144  AttrListPtr removeAttr(unsigned Idx, Attributes Attrs) const;
145
146  //===--------------------------------------------------------------------===//
147  // Attribute List Accessors
148  //===--------------------------------------------------------------------===//
149  /// getParamAttributes - The attributes for the specified index are
150  /// returned.
151  Attributes getParamAttributes(unsigned Idx) const {
152    assert (Idx && Idx != ~0U && "Invalid parameter index!");
153    return getAttributes(Idx);
154  }
155
156  /// getRetAttributes - The attributes for the ret value are
157  /// returned.
158  Attributes getRetAttributes() const {
159    return getAttributes(0);
160  }
161
162  /// getFnAttributes - The function attributes are  returned.
163  Attributes getFnAttributes() const {
164    return getAttributes(~0);
165  }
166
167  /// paramHasAttr - Return true if the specified parameter index has the
168  /// specified attribute set.
169  bool paramHasAttr(unsigned Idx, Attributes Attr) const {
170    return getAttributes(Idx) & Attr;
171  }
172
173  /// getParamAlignment - Return the alignment for the specified function
174  /// parameter.
175  unsigned getParamAlignment(unsigned Idx) const {
176    return (getAttributes(Idx) & Attribute::Alignment) >> 16;
177  }
178
179  /// hasAttrSomewhere - Return true if the specified attribute is set for at
180  /// least one parameter or for the return value.
181  bool hasAttrSomewhere(Attributes Attr) const;
182
183  /// operator==/!= - Provide equality predicates.
184  bool operator==(const AttrListPtr &RHS) const { return AttrList == RHS.AttrList; }
185  bool operator!=(const AttrListPtr &RHS) const { return AttrList != RHS.AttrList; }
186
187  void dump() const;
188
189  //===--------------------------------------------------------------------===//
190  // Attribute List Introspection
191  //===--------------------------------------------------------------------===//
192
193  /// getRawPointer - Return a raw pointer that uniquely identifies this
194  /// attribute list.
195  void *getRawPointer() const {
196    return AttrList;
197  }
198
199  // Attributes are stored as a dense set of slots, where there is one
200  // slot for each argument that has an attribute.  This allows walking over the
201  // dense set instead of walking the sparse list of attributes.
202
203  /// isEmpty - Return true if there are no attributes.
204  ///
205  bool isEmpty() const {
206    return AttrList == 0;
207  }
208
209  /// getNumSlots - Return the number of slots used in this attribute list.
210  /// This is the number of arguments that have an attribute set on them
211  /// (including the function itself).
212  unsigned getNumSlots() const;
213
214  /// getSlot - Return the AttributeWithIndex at the specified slot.  This
215  /// holds a index number plus a set of attributes.
216  const AttributeWithIndex &getSlot(unsigned Slot) const;
217
218private:
219  explicit AttrListPtr(AttributeListImpl *L);
220
221  /// getAttributes - The attributes for the specified index are
222  /// returned.  Attributes for the result are denoted with Idx = 0.
223  Attributes getAttributes(unsigned Idx) const;
224
225};
226
227} // End llvm namespace
228
229#endif
230