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