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author | Reid Spencer <rspencer@reidspencer.com> | 2007-04-22 17:28:03 +0000 |
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committer | Reid Spencer <rspencer@reidspencer.com> | 2007-04-22 17:28:03 +0000 |
commit | b90909e40536db17665727f5ca1c618e485464c3 (patch) | |
tree | 770b735b61c9866050ceb8d3705dc80a582d70a8 /include/llvm/ParameterAttributes.h | |
parent | 7aaa4a5c09d7c9a53ccf2c856c8ba6fe31f14302 (diff) | |
download | external_llvm-b90909e40536db17665727f5ca1c618e485464c3.zip external_llvm-b90909e40536db17665727f5ca1c618e485464c3.tar.gz external_llvm-b90909e40536db17665727f5ca1c618e485464c3.tar.bz2 |
For PR1136:
Add reference counting to ParamAttrsList and make use of it in Function,
CallInst and InvokeInst classes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36346 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'include/llvm/ParameterAttributes.h')
-rw-r--r-- | include/llvm/ParameterAttributes.h | 68 |
1 files changed, 50 insertions, 18 deletions
diff --git a/include/llvm/ParameterAttributes.h b/include/llvm/ParameterAttributes.h index 4c4b0c7..86287e0 100644 --- a/include/llvm/ParameterAttributes.h +++ b/include/llvm/ParameterAttributes.h @@ -21,13 +21,13 @@ #include "llvm/ADT/FoldingSet.h" namespace llvm { - -/// Function parameters can have attributes to indicate how they should be -/// treated by optimizations and code generation. This enumeration lists the -/// attributes that can be associated with parameters or function results. -/// @brief Function parameter attributes. namespace ParamAttr { +/// Function parameters and results can have attributes to indicate how they +/// should be treated by optimizations and code generation. This enumeration +/// lists the attributes that can be associated with parameters or function +/// results. +/// @brief Function parameter attributes. enum Attributes { None = 0, ///< No attributes have been set ZExt = 1 << 0, ///< zero extended before/after call @@ -41,7 +41,7 @@ enum Attributes { } /// This is just a pair of values to associate a set of parameter attributes -/// with a parameter index. +/// with a parameter index. /// @brief ParameterAttributes with a parameter index. struct ParamAttrsWithIndex { uint16_t attrs; ///< The attributes that are set, |'d together @@ -51,29 +51,43 @@ struct ParamAttrsWithIndex { /// @brief A vector of attribute/index pairs. typedef SmallVector<ParamAttrsWithIndex,4> ParamAttrsVector; +/// @brief A more friendly way to reference the attributes. typedef ParamAttr::Attributes ParameterAttributes; -/// This class is used by Function and CallInst to represent the set of -/// parameter attributes used. It represents a list of pairs of uint16_t, one -/// for the parameter index, and one a set of ParameterAttributes bits. -/// Parameters that have no attributes are not present in the list. The list -/// may also be empty, but this doesn't occur in practice. The list constructs -/// as empty and is filled by the insert method. The list can be turned into -/// a string of mnemonics suitable for LLVM Assembly output. Various accessors -/// are provided to obtain information about the attributes. +/// This class represents a list of attribute/index pairs for parameter +/// attributes. Each entry in the list contains the index of a function +/// parameter and the associated ParameterAttributes. If a parameter's index is +/// not present in the list, then no attributes are set for that parameter. The +/// list may also be empty, but this does not occur in practice. An item in +/// the list with an index of 0 refers to the function as a whole or its result. +/// To construct a ParamAttrsList, you must first fill a ParamAttrsVector with +/// the attribute/index pairs you wish to set. The list of attributes can be +/// turned into a string of mnemonics suitable for LLVM Assembly output. +/// Various accessors are provided to obtain information about the attributes. +/// Note that objects of this class are "uniqued". The \p get method can return +/// the pointer of an existing and identical instance. Consequently, reference +/// counting is necessary in order to determine when the last reference to a +/// ParamAttrsList of a given shape is dropped. Users of this class should use +/// the addRef and dropRef methods to add/drop references. When the reference +/// count goes to zero, the ParamAttrsList object is deleted. +/// This class is used by Function, CallInst and InvokeInst to represent their +/// sets of parameter attributes. /// @brief A List of ParameterAttributes. class ParamAttrsList : public FoldingSetNode { /// @name Construction /// @{ private: - // ParamAttrsList is uniqued, thes should not be publicly available + // ParamAttrsList is uniqued, these should not be publicly available void operator=(const ParamAttrsList &); // Do not implement ParamAttrsList(const ParamAttrsList &); // Do not implement ParamAttrsList(); // Do not implement - ~ParamAttrsList() {} // Not public! + ~ParamAttrsList(); // Private implementation + /// Only the \p get method can invoke this when it wants to create a + /// new instance. /// @brief Construct an ParamAttrsList from a ParamAttrsVector - explicit ParamAttrsList(const ParamAttrsVector &attrVec) : attrs(attrVec) {} + explicit ParamAttrsList(const ParamAttrsVector &attrVec) + : attrs(attrVec), refCount(0) {} public: /// This method ensures the uniqueness of ParamAttrsList instances. The @@ -156,6 +170,23 @@ class ParamAttrsList : public FoldingSetNode { /// @brief Return the number of parameter attributes this type has. unsigned size() const { return attrs.size(); } + /// Classes retaining references to ParamAttrsList objects should call this + /// method to increment the reference count. This ensures that the + /// ParamAttrsList object will not disappear until the class drops it. + /// @brief Add a reference to this instance. + void addRef() const { refCount++; } + + /// Classes retaining references to ParamAttrsList objects should call this + /// method to decrement the reference count and possibly delete the + /// ParamAttrsList object. This ensures that ParamAttrsList objects are + /// cleaned up only when the last reference to them is dropped. + /// @brief Drop a reference to this instance. + void dropRef() const { + assert(refCount != 0 && "dropRef without addRef"); + if (--refCount == 0) + delete this; + } + /// @} /// @name Implementation Details /// @{ @@ -167,7 +198,8 @@ class ParamAttrsList : public FoldingSetNode { /// @name Data /// @{ private: - ParamAttrsVector attrs; ///< The list of attributes + ParamAttrsVector attrs; ///< The list of attributes + mutable unsigned refCount; ///< The number of references to this object /// @} }; |