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
46 /// This is just a pair of values to associate a set of parameter attributes
47 /// with a parameter index.
48 /// @brief ParameterAttributes with a parameter index.
49 struct ParamAttrsWithIndex {
50 uint16_t attrs; ///< The attributes that are set, |'d together
51 uint16_t index; ///< Index of the parameter for which the attributes apply
53 static ParamAttrsWithIndex get(uint16_t idx, uint16_t attrs) {
54 ParamAttrsWithIndex P;
61 /// @brief A vector of attribute/index pairs.
62 typedef SmallVector<ParamAttrsWithIndex,4> ParamAttrsVector;
64 /// @brief A more friendly way to reference the attributes.
65 typedef ParamAttr::Attributes ParameterAttributes;
67 /// This class represents a list of attribute/index pairs for parameter
68 /// attributes. Each entry in the list contains the index of a function
69 /// parameter and the associated ParameterAttributes. If a parameter's index is
70 /// not present in the list, then no attributes are set for that parameter. The
71 /// list may also be empty, but this does not occur in practice. An item in
72 /// the list with an index of 0 refers to the function as a whole or its result.
73 /// To construct a ParamAttrsList, you must first fill a ParamAttrsVector with
74 /// the attribute/index pairs you wish to set. The list of attributes can be
75 /// turned into a string of mnemonics suitable for LLVM Assembly output.
76 /// Various accessors are provided to obtain information about the attributes.
77 /// Note that objects of this class are "uniqued". The \p get method can return
78 /// the pointer of an existing and identical instance. Consequently, reference
79 /// counting is necessary in order to determine when the last reference to a
80 /// ParamAttrsList of a given shape is dropped. Users of this class should use
81 /// the addRef and dropRef methods to add/drop references. When the reference
82 /// count goes to zero, the ParamAttrsList object is deleted.
83 /// This class is used by Function, CallInst and InvokeInst to represent their
84 /// sets of parameter attributes.
85 /// @brief A List of ParameterAttributes.
86 class ParamAttrsList : public FoldingSetNode {
87 /// @name Construction
90 // ParamAttrsList is uniqued, these should not be publicly available
91 void operator=(const ParamAttrsList &); // Do not implement
92 ParamAttrsList(const ParamAttrsList &); // Do not implement
93 ParamAttrsList(); // Do not implement
94 ~ParamAttrsList(); // Private implementation
96 /// Only the \p get method can invoke this when it wants to create a
98 /// @brief Construct an ParamAttrsList from a ParamAttrsVector
99 explicit ParamAttrsList(const ParamAttrsVector &attrVec)
100 : attrs(attrVec), refCount(0) {}
103 /// This method ensures the uniqueness of ParamAttrsList instances. The
104 /// argument is a vector of attribute/index pairs as represented by the
105 /// ParamAttrsWithIndex structure. The vector is used in the construction of
106 /// the ParamAttrsList instance. If an instance with identical vector pairs
107 /// exists, it will be returned instead of creating a new instance.
108 /// @brief Get a ParamAttrsList instance.
109 static ParamAttrsList *get(const ParamAttrsVector &attrVec);
115 /// The parameter attributes for the \p indexth parameter are returned.
116 /// The 0th parameter refers to the return type of the function. Note that
117 /// the \p param_index is an index into the function's parameters, not an
118 /// index into this class's list of attributes. The result of getParamIndex
119 /// is always suitable input to this function.
120 /// @returns The all the ParameterAttributes for the \p indexth parameter
121 /// as a uint16_t of enumeration values OR'd together.
122 /// @brief Get the attributes for a parameter
123 uint16_t getParamAttrs(uint16_t param_index) const;
125 /// This checks to see if the \p ith function parameter has the parameter
126 /// attribute given by \p attr set.
127 /// @returns true if the parameter attribute is set
128 /// @brief Determine if a ParameterAttributes is set
129 bool paramHasAttr(uint16_t i, ParameterAttributes attr) const {
130 return getParamAttrs(i) & attr;
133 /// The set of ParameterAttributes set in Attributes is converted to a
134 /// string of equivalent mnemonics. This is, presumably, for writing out
135 /// the mnemonics for the assembly writer.
136 /// @brief Convert parameter attribute bits to text
137 static std::string getParamAttrsText(uint16_t Attributes);
139 /// The \p Indexth parameter attribute is converted to string.
140 /// @brief Get the text for the parmeter attributes for one parameter.
141 std::string getParamAttrsTextByIndex(uint16_t Index) const {
142 return getParamAttrsText(getParamAttrs(Index));
145 /// @brief Comparison operator for ParamAttrsList
146 bool operator < (const ParamAttrsList& that) const {
147 if (this->attrs.size() < that.attrs.size())
149 if (this->attrs.size() > that.attrs.size())
151 for (unsigned i = 0; i < attrs.size(); ++i) {
152 if (attrs[i].index < that.attrs[i].index)
154 if (attrs[i].index > that.attrs[i].index)
156 if (attrs[i].attrs < that.attrs[i].attrs)
158 if (attrs[i].attrs > that.attrs[i].attrs)
164 /// Returns the parameter index of a particular parameter attribute in this
165 /// list of attributes. Note that the attr_index is an index into this
166 /// class's list of attributes, not the index of a parameter. The result
167 /// is the index of the parameter. Clients generally should not use this
168 /// method. It is used internally by LLVM.
169 /// @brief Get a parameter index
170 uint16_t getParamIndex(unsigned attr_index) const {
171 return attrs[attr_index].index;
174 uint16_t getParamAttrsAtIndex(unsigned attr_index) const {
175 return attrs[attr_index].attrs;
178 /// Determines how many parameter attributes are set in this ParamAttrsList.
179 /// This says nothing about how many parameters the function has. It also
180 /// says nothing about the highest parameter index that has attributes.
181 /// Clients generally should not use this method. It is used internally by
183 /// @returns the number of parameter attributes in this ParamAttrsList.
184 /// @brief Return the number of parameter attributes this type has.
185 unsigned size() const { return attrs.size(); }
187 /// Classes retaining references to ParamAttrsList objects should call this
188 /// method to increment the reference count. This ensures that the
189 /// ParamAttrsList object will not disappear until the class drops it.
190 /// @brief Add a reference to this instance.
191 void addRef() const { refCount++; }
193 /// Classes retaining references to ParamAttrsList objects should call this
194 /// method to decrement the reference count and possibly delete the
195 /// ParamAttrsList object. This ensures that ParamAttrsList objects are
196 /// cleaned up only when the last reference to them is dropped.
197 /// @brief Drop a reference to this instance.
198 void dropRef() const {
199 assert(refCount != 0 && "dropRef without addRef");
205 /// @name Implementation Details
208 void Profile(FoldingSetNodeID &ID) const;
215 ParamAttrsVector attrs; ///< The list of attributes
216 mutable unsigned refCount; ///< The number of references to this object
220 } // End llvm namespace