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update symtab section to reflect recent changes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34340 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner
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@ -129,7 +129,7 @@ with another <tt>Value</tt></a> </li>
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<li><a href="#AbstractTypeUser">The AbstractTypeUser Class</a></li>
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</ul></li>
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<li><a href="#SymbolTable">The <tt>SymbolTable</tt> class </a></li>
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<li><a href="#SymbolTable">The <tt>ValueSymbolTable</tt> and <tt>TypeSymbolTable</tt> classes </a></li>
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</ul></li>
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<li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
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@ -2045,12 +2045,8 @@ Type is maintained by PATypeHolder objects.
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<p>
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Some data structures need more to perform more complex updates when types get
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resolved. The <a href="#SymbolTable">SymbolTable</a> class, for example, needs
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move and potentially merge type planes in its representation when a pointer
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changes.</p>
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<p>
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To support this, a class can derive from the AbstractTypeUser class. This class
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resolved. To support this, a class can derive from the AbstractTypeUser class.
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This class
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allows it to get callbacks when certain types are resolved. To register to get
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callbacks for a particular type, the DerivedType::{add/remove}AbstractTypeUser
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methods can be called on a type. Note that these methods only work for <i>
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@ -2062,16 +2058,19 @@ objects) can never be refined.
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<!-- ======================================================================= -->
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<div class="doc_subsection">
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<a name="SymbolTable">The <tt>SymbolTable</tt> class</a>
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<a name="SymbolTable">The <tt>ValueSymbolTable</tt> and
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<tt>TypeSymbolTable</tt> classes</a>
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</div>
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<div class="doc_text">
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<p>This class provides a symbol table that the <a
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<p>The <tt><a href="http://llvm.org/doxygen/classllvm_1_1ValueSymbolTable.html">
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ValueSymbolTable</a></tt> class provides a symbol table that the <a
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href="#Function"><tt>Function</tt></a> and <a href="#Module">
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<tt>Module</tt></a> classes use for naming definitions. The symbol table can
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provide a name for any <a href="#Value"><tt>Value</tt></a>.
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<tt>SymbolTable</tt> is an abstract data type. It hides the data it contains
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and provides access to it through a controlled interface.</p>
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<tt>Module</tt></a> classes use for naming value definitions. The symbol table
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can provide a name for any <a href="#Value"><tt>Value</tt></a>.
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The <tt><a href="http://llvm.org/doxygen/classllvm_1_1TypeSymbolTable.html">
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TypeSymbolTable</a></tt> class is used by the <tt>Module</tt> class to store
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names for types.</p>
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<p>Note that the <tt>SymbolTable</tt> class should not be directly accessed
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by most clients. It should only be used when iteration over the symbol table
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@ -2081,140 +2080,14 @@ all LLVM
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an empty name) do not exist in the symbol table.
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</p>
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<p>To use the <tt>SymbolTable</tt> well, you need to understand the
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structure of the information it holds. The class contains two
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<tt>std::map</tt> objects. The first, <tt>pmap</tt>, is a map of
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<tt>Type*</tt> to maps of name (<tt>std::string</tt>) to <tt>Value*</tt>.
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Thus, Values are stored in two-dimensions and accessed by <tt>Type</tt> and
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name.</p>
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<p>These symbol tables support iteration over the values/types in the symbol
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table with <tt>begin/end/iterator</tt> and supports querying to see if a
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specific name is in the symbol table (with <tt>lookup</tt>). The
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<tt>ValueSymbolTable</tt> class exposes no public mutator methods, instead,
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simply call <tt>setName</tt> on a value, which will autoinsert it into the
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appropriate symbol table. For types, use the Module::addTypeName method to
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insert entries into the symbol table.</p>
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<p>The interface of this class provides three basic types of operations:
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<ol>
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<li><em>Accessors</em>. Accessors provide read-only access to information
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such as finding a value for a name with the
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<a href="#SymbolTable_lookup">lookup</a> method.</li>
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<li><em>Mutators</em>. Mutators allow the user to add information to the
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<tt>SymbolTable</tt> with methods like
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<a href="#SymbolTable_insert"><tt>insert</tt></a>.</li>
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<li><em>Iterators</em>. Iterators allow the user to traverse the content
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of the symbol table in well defined ways, such as the method
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<a href="#SymbolTable_plane_begin"><tt>plane_begin</tt></a>.</li>
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</ol>
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<h3>Accessors</h3>
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<dl>
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<dt><tt>Value* lookup(const Type* Ty, const std::string& name) const</tt>:
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</dt>
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<dd>The <tt>lookup</tt> method searches the type plane given by the
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<tt>Ty</tt> parameter for a <tt>Value</tt> with the provided <tt>name</tt>.
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If a suitable <tt>Value</tt> is not found, null is returned.</dd>
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<dt><tt>bool isEmpty() const</tt>:</dt>
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<dd>This function returns true if both the value and types maps are
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empty</dd>
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</dl>
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<h3>Mutators</h3>
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<dl>
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<dt><tt>void insert(Value *Val)</tt>:</dt>
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<dd>This method adds the provided value to the symbol table. The Value must
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have both a name and a type which are extracted and used to place the value
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in the correct type plane under the value's name.</dd>
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<dt><tt>void remove(Value* Val)</tt>:</dt>
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<dd> This method removes a named value from the symbol table. The
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type and name of the Value are extracted from \p N and used to
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lookup the Value in the correct type plane. If the Value is
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not in the symbol table, this method silently ignores the
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request.</dd>
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</dl>
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<h3>Iteration</h3>
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<p>The following functions describe three types of iterators you can obtain
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the beginning or end of the sequence for both const and non-const. It is
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important to keep track of the different kinds of iterators. There are
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three idioms worth pointing out:</p>
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<table>
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<tr><th>Units</th><th>Iterator</th><th>Idiom</th></tr>
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<tr>
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<td align="left">Planes Of name/Value maps</td><td>PI</td>
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<td align="left"><pre><tt>
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for (SymbolTable::plane_const_iterator PI = ST.plane_begin(),
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PE = ST.plane_end(); PI != PE; ++PI ) {
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PI->first // <i>This is the Type* of the plane</i>
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PI->second // <i>This is the SymbolTable::ValueMap of name/Value pairs</i>
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}
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</tt></pre></td>
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</tr>
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<tr>
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<td align="left">name/Value pairs in a plane</td><td>VI</td>
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<td align="left"><pre><tt>
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for (SymbolTable::value_const_iterator VI = ST.value_begin(SomeType),
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VE = ST.value_end(SomeType); VI != VE; ++VI ) {
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VI->first // <i>This is the name of the Value</i>
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VI->second // <i>This is the Value* value associated with the name</i>
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}
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</tt></pre></td>
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</tr>
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</table>
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<p>Using the recommended iterator names and idioms will help you avoid
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making mistakes. Of particular note, make sure that whenever you use
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value_begin(SomeType) that you always compare the resulting iterator
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with value_end(SomeType) not value_end(SomeOtherType) or else you
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will loop infinitely.</p>
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<dl>
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<dt><tt>plane_iterator plane_begin()</tt>:</dt>
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<dd>Get an iterator that starts at the beginning of the type planes.
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The iterator will iterate over the Type/ValueMap pairs in the
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type planes. </dd>
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<dt><tt>plane_const_iterator plane_begin() const</tt>:</dt>
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<dd>Get a const_iterator that starts at the beginning of the type
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planes. The iterator will iterate over the Type/ValueMap pairs
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in the type planes. </dd>
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<dt><tt>plane_iterator plane_end()</tt>:</dt>
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<dd>Get an iterator at the end of the type planes. This serves as
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the marker for end of iteration over the type planes.</dd>
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<dt><tt>plane_const_iterator plane_end() const</tt>:</dt>
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<dd>Get a const_iterator at the end of the type planes. This serves as
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the marker for end of iteration over the type planes.</dd>
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<dt><tt>value_iterator value_begin(const Type *Typ)</tt>:</dt>
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<dd>Get an iterator that starts at the beginning of a type plane.
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The iterator will iterate over the name/value pairs in the type plane.
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Note: The type plane must already exist before using this.</dd>
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<dt><tt>value_const_iterator value_begin(const Type *Typ) const</tt>:</dt>
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<dd>Get a const_iterator that starts at the beginning of a type plane.
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The iterator will iterate over the name/value pairs in the type plane.
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Note: The type plane must already exist before using this.</dd>
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<dt><tt>value_iterator value_end(const Type *Typ)</tt>:</dt>
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<dd>Get an iterator to the end of a type plane. This serves as the marker
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for end of iteration of the type plane.
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Note: The type plane must already exist before using this.</dd>
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<dt><tt>value_const_iterator value_end(const Type *Typ) const</tt>:</dt>
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<dd>Get a const_iterator to the end of a type plane. This serves as the
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marker for end of iteration of the type plane.
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Note: the type plane must already exist before using this.</dd>
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<dt><tt>plane_const_iterator find(const Type* Typ ) const</tt>:</dt>
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<dd>This method returns a plane_const_iterator for iteration over
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the type planes starting at a specific plane, given by \p Ty.</dd>
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<dt><tt>plane_iterator find( const Type* Typ </tt>:</dt>
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<dd>This method returns a plane_iterator for iteration over the
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type planes starting at a specific plane, given by \p Ty.</dd>
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</dl>
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</div>
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