1 //===-- llvm/ParameterAttributes.h - Container for ParamAttrs ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Reid Spencer and is distributed under the
6 // University of Illinois Open Source 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"
26 /// Function parameters and results can have attributes to indicate how they
27 /// should be treated by optimizations and code generation. This enumeration
28 /// lists the attributes that can be associated with parameters or function
30 /// @brief Function parameter attributes.
32 None = 0, ///< No attributes have been set
33 ZExt = 1 << 0, ///< Zero extended before/after call
34 SExt = 1 << 1, ///< Sign extended before/after call
35 NoReturn = 1 << 2, ///< Mark the function as not returning
36 InReg = 1 << 3, ///< Force argument to be passed in register
37 StructRet = 1 << 4, ///< Hidden pointer to structure to return
38 NoUnwind = 1 << 5, ///< Function doesn't unwind stack
39 NoAlias = 1 << 6, ///< Considered to not alias after call
40 ByVal = 1 << 7, ///< Pass structure by value
41 Nest = 1 << 8, ///< Nested function static chain
42 Pure = 1 << 9, ///< Function is pure
43 Const = 1 << 10 ///< Function is const
48 /// This is just a pair of values to associate a set of parameter attributes
49 /// with a parameter index.
50 /// @brief ParameterAttributes with a parameter index.
51 struct ParamAttrsWithIndex {
52 uint16_t attrs; ///< The attributes that are set, |'d together
53 uint16_t index; ///< Index of the parameter for which the attributes apply
55 static ParamAttrsWithIndex get(uint16_t idx, uint16_t attrs) {
56 ParamAttrsWithIndex P;
63 /// @brief A vector of attribute/index pairs.
64 typedef SmallVector<ParamAttrsWithIndex,4> ParamAttrsVector;
66 /// @brief A more friendly way to reference the attributes.
67 typedef ParamAttr::Attributes ParameterAttributes;
69 /// This class represents a list of attribute/index pairs for parameter
70 /// attributes. Each entry in the list contains the index of a function
71 /// parameter and the associated ParameterAttributes. If a parameter's index is
72 /// not present in the list, then no attributes are set for that parameter. The
73 /// list may also be empty, but this does not occur in practice. An item in
74 /// the list with an index of 0 refers to the function as a whole or its result.
75 /// To construct a ParamAttrsList, you must first fill a ParamAttrsVector with
76 /// the attribute/index pairs you wish to set. The list of attributes can be
77 /// turned into a string of mnemonics suitable for LLVM Assembly output.
78 /// Various accessors are provided to obtain information about the attributes.
79 /// Note that objects of this class are "uniqued". The \p get method can return
80 /// the pointer of an existing and identical instance. Consequently, reference
81 /// counting is necessary in order to determine when the last reference to a
82 /// ParamAttrsList of a given shape is dropped. Users of this class should use
83 /// the addRef and dropRef methods to add/drop references. When the reference
84 /// count goes to zero, the ParamAttrsList object is deleted.
85 /// This class is used by Function, CallInst and InvokeInst to represent their
86 /// sets of parameter attributes.
87 /// @brief A List of ParameterAttributes.
88 class ParamAttrsList : public FoldingSetNode {
89 /// @name Construction
92 // ParamAttrsList is uniqued, these should not be publicly available
93 void operator=(const ParamAttrsList &); // Do not implement
94 ParamAttrsList(const ParamAttrsList &); // Do not implement
95 ParamAttrsList(); // Do not implement
96 ~ParamAttrsList(); // Private implementation
98 /// Only the \p get method can invoke this when it wants to create a
100 /// @brief Construct an ParamAttrsList from a ParamAttrsVector
101 explicit ParamAttrsList(const ParamAttrsVector &attrVec)
102 : attrs(attrVec), refCount(0) {}
105 /// This method ensures the uniqueness of ParamAttrsList instances. The
106 /// argument is a vector of attribute/index pairs as represented by the
107 /// ParamAttrsWithIndex structure. The vector is used in the construction of
108 /// the ParamAttrsList instance. If an instance with identical vector pairs
109 /// exists, it will be returned instead of creating a new instance.
110 /// @brief Get a ParamAttrsList instance.
111 static ParamAttrsList *get(const ParamAttrsVector &attrVec);
117 /// The parameter attributes for the \p indexth parameter are returned.
118 /// The 0th parameter refers to the return type of the function. Note that
119 /// the \p param_index is an index into the function's parameters, not an
120 /// index into this class's list of attributes. The result of getParamIndex
121 /// is always suitable input to this function.
122 /// @returns The all the ParameterAttributes for the \p indexth parameter
123 /// as a uint16_t of enumeration values OR'd together.
124 /// @brief Get the attributes for a parameter
125 uint16_t getParamAttrs(uint16_t param_index) const;
127 /// This checks to see if the \p ith function parameter has the parameter
128 /// attribute given by \p attr set.
129 /// @returns true if the parameter attribute is set
130 /// @brief Determine if a ParameterAttributes is set
131 bool paramHasAttr(uint16_t i, ParameterAttributes attr) const {
132 return getParamAttrs(i) & attr;
135 /// The set of ParameterAttributes set in Attributes is converted to a
136 /// string of equivalent mnemonics. This is, presumably, for writing out
137 /// the mnemonics for the assembly writer.
138 /// @brief Convert parameter attribute bits to text
139 static std::string getParamAttrsText(uint16_t Attributes);
141 /// The \p Indexth parameter attribute is converted to string.
142 /// @brief Get the text for the parmeter attributes for one parameter.
143 std::string getParamAttrsTextByIndex(uint16_t Index) const {
144 return getParamAttrsText(getParamAttrs(Index));
147 /// @brief Comparison operator for ParamAttrsList
148 bool operator < (const ParamAttrsList& that) const {
149 if (this->attrs.size() < that.attrs.size())
151 if (this->attrs.size() > that.attrs.size())
153 for (unsigned i = 0; i < attrs.size(); ++i) {
154 if (attrs[i].index < that.attrs[i].index)
156 if (attrs[i].index > that.attrs[i].index)
158 if (attrs[i].attrs < that.attrs[i].attrs)
160 if (attrs[i].attrs > that.attrs[i].attrs)
166 /// Returns the parameter index of a particular parameter attribute in this
167 /// list of attributes. Note that the attr_index is an index into this
168 /// class's list of attributes, not the index of a parameter. The result
169 /// is the index of the parameter. Clients generally should not use this
170 /// method. It is used internally by LLVM.
171 /// @brief Get a parameter index
172 uint16_t getParamIndex(unsigned attr_index) const {
173 return attrs[attr_index].index;
176 uint16_t getParamAttrsAtIndex(unsigned attr_index) const {
177 return attrs[attr_index].attrs;
180 /// Determines how many parameter attributes are set in this ParamAttrsList.
181 /// This says nothing about how many parameters the function has. It also
182 /// says nothing about the highest parameter index that has attributes.
183 /// Clients generally should not use this method. It is used internally by
185 /// @returns the number of parameter attributes in this ParamAttrsList.
186 /// @brief Return the number of parameter attributes this type has.
187 unsigned size() const { return attrs.size(); }
189 /// Classes retaining references to ParamAttrsList objects should call this
190 /// method to increment the reference count. This ensures that the
191 /// ParamAttrsList object will not disappear until the class drops it.
192 /// @brief Add a reference to this instance.
193 void addRef() const { refCount++; }
195 /// Classes retaining references to ParamAttrsList objects should call this
196 /// method to decrement the reference count and possibly delete the
197 /// ParamAttrsList object. This ensures that ParamAttrsList objects are
198 /// cleaned up only when the last reference to them is dropped.
199 /// @brief Drop a reference to this instance.
200 void dropRef() const {
201 assert(refCount != 0 && "dropRef without addRef");
207 /// @name Implementation Details
210 void Profile(FoldingSetNodeID &ID) const;
217 ParamAttrsVector attrs; ///< The list of attributes
218 mutable unsigned refCount; ///< The number of references to this object
222 } // End llvm namespace