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 Parameter attributes that do not apply to vararg call arguments.
56 const uint16_t VarArgsIncompatible = StructRet;
58 /// @brief Attributes that are mutually incompatible.
59 const uint16_t MutuallyIncompatible[3] = {
60 ByVal | InReg | Nest | StructRet,
65 /// @brief Which attributes cannot be applied to a type.
66 uint16_t typeIncompatible (const Type *Ty);
68 } // end namespace ParamAttr
70 /// This is just a pair of values to associate a set of parameter attributes
71 /// with a parameter index.
72 /// @brief ParameterAttributes with a parameter index.
73 struct ParamAttrsWithIndex {
74 uint16_t attrs; ///< The attributes that are set, or'd together
75 uint16_t index; ///< Index of the parameter for which the attributes apply
77 static ParamAttrsWithIndex get(uint16_t idx, uint16_t attrs) {
78 ParamAttrsWithIndex P;
85 /// @brief A vector of attribute/index pairs.
86 typedef SmallVector<ParamAttrsWithIndex,4> ParamAttrsVector;
88 /// @brief A more friendly way to reference the attributes.
89 typedef ParamAttr::Attributes ParameterAttributes;
91 /// This class represents a list of attribute/index pairs for parameter
92 /// attributes. Each entry in the list contains the index of a function
93 /// parameter and the associated ParameterAttributes. If a parameter's index is
94 /// not present in the list, then no attributes are set for that parameter. The
95 /// list may also be empty, but this does not occur in practice. An item in
96 /// the list with an index of 0 refers to the function as a whole or its result.
97 /// To construct a ParamAttrsList, you must first fill a ParamAttrsVector with
98 /// the attribute/index pairs you wish to set. The list of attributes can be
99 /// turned into a string of mnemonics suitable for LLVM Assembly output.
100 /// Various accessors are provided to obtain information about the attributes.
101 /// Note that objects of this class are "uniqued". The \p get method can return
102 /// the pointer of an existing and identical instance. Consequently, reference
103 /// counting is necessary in order to determine when the last reference to a
104 /// ParamAttrsList of a given shape is dropped. Users of this class should use
105 /// the addRef and dropRef methods to add/drop references. When the reference
106 /// count goes to zero, the ParamAttrsList object is deleted.
107 /// This class is used by Function, CallInst and InvokeInst to represent their
108 /// sets of parameter attributes.
109 /// @brief A List of ParameterAttributes.
110 class ParamAttrsList : public FoldingSetNode {
111 /// @name Construction
114 // ParamAttrsList is uniqued, these should not be publicly available
115 void operator=(const ParamAttrsList &); // Do not implement
116 ParamAttrsList(const ParamAttrsList &); // Do not implement
117 ~ParamAttrsList(); // Private implementation
119 /// Only the \p get method can invoke this when it wants to create a
121 /// @brief Construct an ParamAttrsList from a ParamAttrsVector
122 explicit ParamAttrsList(const ParamAttrsVector &attrVec);
125 /// This method ensures the uniqueness of ParamAttrsList instances. The
126 /// argument is a vector of attribute/index pairs as represented by the
127 /// ParamAttrsWithIndex structure. The index values must be in strictly
128 /// increasing order and ParamAttr::None is not allowed. The vector is
129 /// used to construct the ParamAttrsList instance. If an instance with
130 /// identical vector pairs exists, it will be returned instead of creating
132 /// @brief Get a ParamAttrsList instance.
133 static const ParamAttrsList *get(const ParamAttrsVector &attrVec);
135 /// Returns the ParamAttrsList obtained by modifying PAL using the supplied
136 /// list of attribute/index pairs. Any existing attributes for the given
137 /// index are replaced by the given attributes. If there were no attributes
138 /// then the new ones are inserted. Attributes can be deleted by replacing
139 /// them with ParamAttr::None. Index values must be strictly increasing.
140 /// @brief Get a new ParamAttrsList instance by modifying an existing one.
141 static const ParamAttrsList *getModified(const ParamAttrsList *PAL,
142 const ParamAttrsVector &modVec);
144 /// @brief Add the specified attributes to those in PAL at index idx.
145 static const ParamAttrsList *includeAttrs(const ParamAttrsList *PAL,
146 uint16_t idx, uint16_t attrs);
148 /// @brief Remove the specified attributes from those in PAL at index idx.
149 static const ParamAttrsList *excludeAttrs(const ParamAttrsList *PAL,
150 uint16_t idx, uint16_t attrs);
156 /// The parameter attributes for the \p indexth parameter are returned.
157 /// The 0th parameter refers to the return type of the function. Note that
158 /// the \p param_index is an index into the function's parameters, not an
159 /// index into this class's list of attributes. The result of getParamIndex
160 /// is always suitable input to this function.
161 /// @returns The all the ParameterAttributes for the \p indexth parameter
162 /// as a uint16_t of enumeration values OR'd together.
163 /// @brief Get the attributes for a parameter
164 uint16_t getParamAttrs(uint16_t param_index) const;
166 /// This checks to see if the \p ith function parameter has the parameter
167 /// attribute given by \p attr set.
168 /// @returns true if the parameter attribute is set
169 /// @brief Determine if a ParameterAttributes is set
170 bool paramHasAttr(uint16_t i, ParameterAttributes attr) const {
171 return getParamAttrs(i) & attr;
174 /// This returns whether the given attribute is set for at least one
175 /// parameter or for the return value.
176 /// @returns true if the parameter attribute is set somewhere
177 /// @brief Determine if a ParameterAttributes is set somewhere
178 bool hasAttrSomewhere(ParameterAttributes attr) const;
180 /// The set of ParameterAttributes set in Attributes is converted to a
181 /// string of equivalent mnemonics. This is, presumably, for writing out
182 /// the mnemonics for the assembly writer.
183 /// @brief Convert parameter attribute bits to text
184 static std::string getParamAttrsText(uint16_t Attributes);
186 /// The \p Indexth parameter attribute is converted to string.
187 /// @brief Get the text for the parmeter attributes for one parameter.
188 std::string getParamAttrsTextByIndex(uint16_t Index) const {
189 return getParamAttrsText(getParamAttrs(Index));
192 /// @brief Comparison operator for ParamAttrsList
193 bool operator < (const ParamAttrsList& that) const {
194 if (this->attrs.size() < that.attrs.size())
196 if (this->attrs.size() > that.attrs.size())
198 for (unsigned i = 0; i < attrs.size(); ++i) {
199 if (attrs[i].index < that.attrs[i].index)
201 if (attrs[i].index > that.attrs[i].index)
203 if (attrs[i].attrs < that.attrs[i].attrs)
205 if (attrs[i].attrs > that.attrs[i].attrs)
211 /// Returns the parameter index of a particular parameter attribute in this
212 /// list of attributes. Note that the attr_index is an index into this
213 /// class's list of attributes, not the index of a parameter. The result
214 /// is the index of the parameter. Clients generally should not use this
215 /// method. It is used internally by LLVM.
216 /// @brief Get a parameter index
217 uint16_t getParamIndex(unsigned attr_index) const {
218 return attrs[attr_index].index;
221 uint16_t getParamAttrsAtIndex(unsigned attr_index) const {
222 return attrs[attr_index].attrs;
225 /// Determines how many parameter attributes are set in this ParamAttrsList.
226 /// This says nothing about how many parameters the function has. It also
227 /// says nothing about the highest parameter index that has attributes.
228 /// Clients generally should not use this method. It is used internally by
230 /// @returns the number of parameter attributes in this ParamAttrsList.
231 /// @brief Return the number of parameter attributes this type has.
232 unsigned size() const { return attrs.size(); }
234 /// @brief Return the number of references to this ParamAttrsList.
235 unsigned numRefs() const { return refCount; }
241 /// Classes retaining references to ParamAttrsList objects should call this
242 /// method to increment the reference count. This ensures that the
243 /// ParamAttrsList object will not disappear until the class drops it.
244 /// @brief Add a reference to this instance.
245 void addRef() const { refCount++; }
247 /// Classes retaining references to ParamAttrsList objects should call this
248 /// method to decrement the reference count and possibly delete the
249 /// ParamAttrsList object. This ensures that ParamAttrsList objects are
250 /// cleaned up only when the last reference to them is dropped.
251 /// @brief Drop a reference to this instance.
252 void dropRef() const {
253 assert(refCount != 0 && "dropRef without addRef");
259 /// @name Implementation Details
262 void Profile(FoldingSetNodeID &ID) const {
265 static void Profile(FoldingSetNodeID &ID, const ParamAttrsVector &Attrs);
272 ParamAttrsVector attrs; ///< The list of attributes
273 mutable unsigned refCount; ///< The number of references to this object
277 } // End llvm namespace