1 //===-- llvm/ParameterAttributes.h - Container for ParamAttrs ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the types necessary to represent the parameter attributes
11 // associated with functions and their calls.
13 // The implementations of these classes live in lib/VMCore/Function.cpp.
15 //===----------------------------------------------------------------------===//
17 #ifndef LLVM_PARAMETER_ATTRIBUTES_H
18 #define LLVM_PARAMETER_ATTRIBUTES_H
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/FoldingSet.h"
29 /// Function parameters and results can have attributes to indicate how they
30 /// should be treated by optimizations and code generation. This enumeration
31 /// lists the attributes that can be associated with parameters or function
33 /// @brief Function parameter attributes.
35 None = 0, ///< No attributes have been set
36 ZExt = 1 << 0, ///< Zero extended before/after call
37 SExt = 1 << 1, ///< Sign extended before/after call
38 NoReturn = 1 << 2, ///< Mark the function as not returning
39 InReg = 1 << 3, ///< Force argument to be passed in register
40 StructRet = 1 << 4, ///< Hidden pointer to structure to return
41 NoUnwind = 1 << 5, ///< Function doesn't unwind stack
42 NoAlias = 1 << 6, ///< Considered to not alias after call
43 ByVal = 1 << 7, ///< Pass structure by value
44 Nest = 1 << 8, ///< Nested function static chain
45 ReadNone = 1 << 9, ///< Function does not access memory
46 ReadOnly = 1 << 10 ///< Function only reads from memory
49 /// @brief Attributes that only apply to function parameters.
50 const uint16_t ParameterOnly = ByVal | InReg | Nest | StructRet;
52 /// @brief Attributes that only apply to function return values.
53 const uint16_t ReturnOnly = NoReturn | NoUnwind | ReadNone | ReadOnly;
55 /// @brief Attributes that only apply to integers.
56 const uint16_t IntegerTypeOnly = SExt | ZExt;
58 /// @brief Attributes that only apply to pointers.
59 const uint16_t PointerTypeOnly = ByVal | Nest | NoAlias | StructRet;
61 /// @brief Attributes that are mutually incompatible.
62 const uint16_t MutuallyIncompatible[3] = {
63 ByVal | InReg | Nest | StructRet,
68 /// @brief Which of the given attributes do not apply to the type.
69 uint16_t incompatibleWithType (const Type *Ty, uint16_t attrs);
71 } // end namespace ParamAttr
73 /// This is just a pair of values to associate a set of parameter attributes
74 /// with a parameter index.
75 /// @brief ParameterAttributes with a parameter index.
76 struct ParamAttrsWithIndex {
77 uint16_t attrs; ///< The attributes that are set, or'd together
78 uint16_t index; ///< Index of the parameter for which the attributes apply
80 static ParamAttrsWithIndex get(uint16_t idx, uint16_t attrs) {
81 ParamAttrsWithIndex P;
88 /// @brief A vector of attribute/index pairs.
89 typedef SmallVector<ParamAttrsWithIndex,4> ParamAttrsVector;
91 /// @brief A more friendly way to reference the attributes.
92 typedef ParamAttr::Attributes ParameterAttributes;
94 /// This class represents a list of attribute/index pairs for parameter
95 /// attributes. Each entry in the list contains the index of a function
96 /// parameter and the associated ParameterAttributes. If a parameter's index is
97 /// not present in the list, then no attributes are set for that parameter. The
98 /// list may also be empty, but this does not occur in practice. An item in
99 /// the list with an index of 0 refers to the function as a whole or its result.
100 /// To construct a ParamAttrsList, you must first fill a ParamAttrsVector with
101 /// the attribute/index pairs you wish to set. The list of attributes can be
102 /// turned into a string of mnemonics suitable for LLVM Assembly output.
103 /// Various accessors are provided to obtain information about the attributes.
104 /// Note that objects of this class are "uniqued". The \p get method can return
105 /// the pointer of an existing and identical instance. Consequently, reference
106 /// counting is necessary in order to determine when the last reference to a
107 /// ParamAttrsList of a given shape is dropped. Users of this class should use
108 /// the addRef and dropRef methods to add/drop references. When the reference
109 /// count goes to zero, the ParamAttrsList object is deleted.
110 /// This class is used by Function, CallInst and InvokeInst to represent their
111 /// sets of parameter attributes.
112 /// @brief A List of ParameterAttributes.
113 class ParamAttrsList : public FoldingSetNode {
114 /// @name Construction
117 // ParamAttrsList is uniqued, these should not be publicly available
118 void operator=(const ParamAttrsList &); // Do not implement
119 ParamAttrsList(const ParamAttrsList &); // Do not implement
120 ~ParamAttrsList(); // Private implementation
122 /// Only the \p get method can invoke this when it wants to create a
124 /// @brief Construct an ParamAttrsList from a ParamAttrsVector
125 explicit ParamAttrsList(const ParamAttrsVector &attrVec);
128 /// This method ensures the uniqueness of ParamAttrsList instances. The
129 /// argument is a vector of attribute/index pairs as represented by the
130 /// ParamAttrsWithIndex structure. The index values must be in strictly
131 /// increasing order and ParamAttr::None is not allowed. The vector is
132 /// used to construct the ParamAttrsList instance. If an instance with
133 /// identical vector pairs exists, it will be returned instead of creating
135 /// @brief Get a ParamAttrsList instance.
136 static const ParamAttrsList *get(const ParamAttrsVector &attrVec);
138 /// Returns the ParamAttrsList obtained by modifying PAL using the supplied
139 /// list of attribute/index pairs. Any existing attributes for the given
140 /// index are replaced by the given attributes. If there were no attributes
141 /// then the new ones are inserted. Attributes can be deleted by replacing
142 /// them with ParamAttr::None. Index values must be strictly increasing.
143 /// @brief Get a new ParamAttrsList instance by modifying an existing one.
144 static const ParamAttrsList *getModified(const ParamAttrsList *PAL,
145 const ParamAttrsVector &modVec);
147 /// @brief Add the specified attributes to those in PAL at index idx.
148 static const ParamAttrsList *includeAttrs(const ParamAttrsList *PAL,
149 uint16_t idx, uint16_t attrs);
151 /// @brief Remove the specified attributes from those in PAL at index idx.
152 static const ParamAttrsList *excludeAttrs(const ParamAttrsList *PAL,
153 uint16_t idx, uint16_t attrs);
159 /// The parameter attributes for the \p indexth parameter are returned.
160 /// The 0th parameter refers to the return type of the function. Note that
161 /// the \p param_index is an index into the function's parameters, not an
162 /// index into this class's list of attributes. The result of getParamIndex
163 /// is always suitable input to this function.
164 /// @returns The all the ParameterAttributes for the \p indexth parameter
165 /// as a uint16_t of enumeration values OR'd together.
166 /// @brief Get the attributes for a parameter
167 uint16_t getParamAttrs(uint16_t param_index) const;
169 /// This checks to see if the \p ith function parameter has the parameter
170 /// attribute given by \p attr set.
171 /// @returns true if the parameter attribute is set
172 /// @brief Determine if a ParameterAttributes is set
173 bool paramHasAttr(uint16_t i, ParameterAttributes attr) const {
174 return getParamAttrs(i) & attr;
177 /// The set of ParameterAttributes set in Attributes is converted to a
178 /// string of equivalent mnemonics. This is, presumably, for writing out
179 /// the mnemonics for the assembly writer.
180 /// @brief Convert parameter attribute bits to text
181 static std::string getParamAttrsText(uint16_t Attributes);
183 /// The \p Indexth parameter attribute is converted to string.
184 /// @brief Get the text for the parmeter attributes for one parameter.
185 std::string getParamAttrsTextByIndex(uint16_t Index) const {
186 return getParamAttrsText(getParamAttrs(Index));
189 /// @brief Comparison operator for ParamAttrsList
190 bool operator < (const ParamAttrsList& that) const {
191 if (this->attrs.size() < that.attrs.size())
193 if (this->attrs.size() > that.attrs.size())
195 for (unsigned i = 0; i < attrs.size(); ++i) {
196 if (attrs[i].index < that.attrs[i].index)
198 if (attrs[i].index > that.attrs[i].index)
200 if (attrs[i].attrs < that.attrs[i].attrs)
202 if (attrs[i].attrs > that.attrs[i].attrs)
208 /// Returns the parameter index of a particular parameter attribute in this
209 /// list of attributes. Note that the attr_index is an index into this
210 /// class's list of attributes, not the index of a parameter. The result
211 /// is the index of the parameter. Clients generally should not use this
212 /// method. It is used internally by LLVM.
213 /// @brief Get a parameter index
214 uint16_t getParamIndex(unsigned attr_index) const {
215 return attrs[attr_index].index;
218 uint16_t getParamAttrsAtIndex(unsigned attr_index) const {
219 return attrs[attr_index].attrs;
222 /// Determines how many parameter attributes are set in this ParamAttrsList.
223 /// This says nothing about how many parameters the function has. It also
224 /// says nothing about the highest parameter index that has attributes.
225 /// Clients generally should not use this method. It is used internally by
227 /// @returns the number of parameter attributes in this ParamAttrsList.
228 /// @brief Return the number of parameter attributes this type has.
229 unsigned size() const { return attrs.size(); }
231 /// @brief Return the number of references to this ParamAttrsList.
232 unsigned numRefs() const { return refCount; }
238 /// Classes retaining references to ParamAttrsList objects should call this
239 /// method to increment the reference count. This ensures that the
240 /// ParamAttrsList object will not disappear until the class drops it.
241 /// @brief Add a reference to this instance.
242 void addRef() const { refCount++; }
244 /// Classes retaining references to ParamAttrsList objects should call this
245 /// method to decrement the reference count and possibly delete the
246 /// ParamAttrsList object. This ensures that ParamAttrsList objects are
247 /// cleaned up only when the last reference to them is dropped.
248 /// @brief Drop a reference to this instance.
249 void dropRef() const {
250 assert(refCount != 0 && "dropRef without addRef");
256 /// @name Implementation Details
259 void Profile(FoldingSetNodeID &ID) const {
262 static void Profile(FoldingSetNodeID &ID, const ParamAttrsVector &Attrs);
269 ParamAttrsVector attrs; ///< The list of attributes
270 mutable unsigned refCount; ///< The number of references to this object
274 } // End llvm namespace