<li><a href="#dss_deque"><deque></a></li>
<li><a href="#dss_list"><list></a></li>
<li><a href="#dss_ilist">llvm/ADT/ilist</a></li>
+ <li><a href="#dss_other">Other Sequential Container Options</a></li>
</ul></li>
<li><a href="#ds_set">Set-Like Containers (std::set, SmallSet, SetVector, etc)</a>
<ul>
<li><a href="#dss_FoldingSet">"llvm/ADT/FoldingSet.h"</a></li>
<li><a href="#dss_set"><set></a></li>
<li><a href="#dss_setvector">"llvm/ADT/SetVector.h"</a></li>
- <li><a href="#dss_otherset">Other Options</a></li>
+ <li><a href="#dss_uniquevector">"llvm/ADT/UniqueVector.h"</a></li>
+ <li><a href="#dss_otherset">Other Set-Like ContainerOptions</a></li>
+ </ul></li>
+ <li><a href="#ds_map">Map-Like Containers (std::map, DenseMap, etc)</a>
+ <ul>
+ <li><a href="#dss_sortedvectormap">A sorted 'vector'</a></li>
+ <li><a href="#dss_stringmap">"llvm/ADT/StringMap.h"</a></li>
+ <li><a href="#dss_indexedmap">"llvm/ADT/IndexedMap.h"</a></li>
+ <li><a href="#dss_densemap">"llvm/ADT/DenseMap.h"</a></li>
+ <li><a href="#dss_map"><map></a></li>
+ <li><a href="#dss_othermap">Other Map-Like Container Options</a></li>
</ul></li>
- <li><a href="#ds_map">Map-Like Containers (std::map, DenseMap, etc)</a></li>
</ul>
</li>
<li><a href="#common">Helpful Hints for Common Operations</a>
<li><a href="#schanges_deleting">Deleting <tt>Instruction</tt>s</a> </li>
<li><a href="#schanges_replacing">Replacing an <tt>Instruction</tt>
with another <tt>Value</tt></a> </li>
+ <li><a href="#schanges_deletingGV">Deleting <tt>GlobalVariable</tt>s</a> </li>
</ul>
</li>
<!--
<li><a href="#AbstractTypeUser">The AbstractTypeUser Class</a></li>
</ul></li>
- <li><a href="#SymbolTable">The <tt>SymbolTable</tt> class </a></li>
+ <li><a href="#SymbolTable">The <tt>ValueSymbolTable</tt> and <tt>TypeSymbolTable</tt> classes </a></li>
</ul></li>
<li><a href="#coreclasses">The Core LLVM Class Hierarchy Reference</a>
<ul>
<li><a href="#Type">The <tt>Type</tt> class</a> </li>
+ <li><a href="#Module">The <tt>Module</tt> class</a></li>
<li><a href="#Value">The <tt>Value</tt> class</a>
+ <ul>
+ <li><a href="#User">The <tt>User</tt> class</a>
<ul>
- <li><a href="#User">The <tt>User</tt> class</a>
+ <li><a href="#Instruction">The <tt>Instruction</tt> class</a></li>
+ <li><a href="#Constant">The <tt>Constant</tt> class</a>
+ <ul>
+ <li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>
<ul>
- <li><a href="#Instruction">The <tt>Instruction</tt> class</a>
- <ul>
- <li><a href="#GetElementPtrInst">The <tt>GetElementPtrInst</tt> class</a></li>
- </ul>
- </li>
- <li><a href="#Module">The <tt>Module</tt> class</a></li>
- <li><a href="#Constant">The <tt>Constant</tt> class</a>
- <ul>
- <li><a href="#GlobalValue">The <tt>GlobalValue</tt> class</a>
- <ul>
- <li><a href="#BasicBlock">The <tt>BasicBlock</tt>class</a></li>
- <li><a href="#Function">The <tt>Function</tt> class</a></li>
- <li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class</a></li>
- </ul>
- </li>
- </ul>
- </li>
- </ul>
- </li>
- <li><a href="#Argument">The <tt>Argument</tt> class</a></li>
+ <li><a href="#Function">The <tt>Function</tt> class</a></li>
+ <li><a href="#GlobalVariable">The <tt>GlobalVariable</tt> class</a></li>
+ </ul>
+ </li>
+ </ul>
+ </li>
</ul>
+ </li>
+ <li><a href="#BasicBlock">The <tt>BasicBlock</tt> class</a></li>
+ <li><a href="#Argument">The <tt>Argument</tt> class</a></li>
+ </ul>
</li>
</ul>
</li>
</pre>
</div>
- <p> When running <tt>gccas</tt> on a C file from the SPEC benchmark
+ <p> When running <tt>opt</tt> on a C file from the SPEC benchmark
suite, it gives a report that looks like this:</p>
<div class="doc_code">
<pre>
- 7646 bytecodewriter - Number of normal instructions
- 725 bytecodewriter - Number of oversized instructions
- 129996 bytecodewriter - Number of bytecode bytes written
+ 7646 bitcodewriter - Number of normal instructions
+ 725 bitcodewriter - Number of oversized instructions
+ 129996 bitcodewriter - Number of bitcode bytes written
2817 raise - Number of insts DCEd or constprop'd
3213 raise - Number of cast-of-self removed
5046 raise - Number of expression trees converted
toolkit, and make sure 'dot' and 'gv' are in your path. If you are running on
Mac OS/X, download and install the Mac OS/X <a
href="http://www.pixelglow.com/graphviz/">Graphviz program</a>, and add
-<tt>/Applications/Graphviz.app/Contents/MacOS/</tt> (or whereever you install
+<tt>/Applications/Graphviz.app/Contents/MacOS/</tt> (or wherever you install
it) to your path. Once in your system and path are set up, rerun the LLVM
configure script and rebuild LLVM to enable this functionality.</p>
<p><tt>SelectionDAG</tt> has been extended to make it easier to locate
<i>interesting</i> nodes in large complex graphs. From gdb, if you
<tt>call DAG.setGraphColor(<i>node</i>, "<i>color</i>")</tt>, then the
-next <tt>call DAG.viewGraph()</tt> would hilight the node in the
+next <tt>call DAG.viewGraph()</tt> would highlight the node in the
specified color (choices of colors can be found at <a
href="http://www.graphviz.org/doc/info/colors.html">colors</a>.) More
complex node attributes can be provided with <tt>call
<div class="doc_text">
-<p>LLVM has a plethora of datastructures in the <tt>llvm/ADT/</tt> directory,
- and we commonly use STL datastructures. This section describes the tradeoffs
+<p>LLVM has a plethora of data structures in the <tt>llvm/ADT/</tt> directory,
+ and we commonly use STL data structures. This section describes the trade-offs
you should consider when you pick one.</p>
<p>
access the container. Based on that, you should use:</p>
<ul>
-<li>a <a href="#ds_map">map-like</a> container if you need efficient lookup
+<li>a <a href="#ds_map">map-like</a> container if you need efficient look-up
of an value based on another value. Map-like containers also support
efficient queries for containment (whether a key is in the map). Map-like
containers generally do not support efficient reverse mapping (values to
<li>a <a href="#ds_sequential">sequential</a> container provides
the most efficient way to add elements and keeps track of the order they are
added to the collection. They permit duplicates and support efficient
- iteration, but do not support efficient lookup based on a key.
+ iteration, but do not support efficient look-up based on a key.
</li>
</ul>
<p>
-Once the proper catagory of container is determined, you can fine tune the
+Once the proper category of container is determined, you can fine tune the
memory use, constant factors, and cache behaviors of access by intelligently
-picking a member of the catagory. Note that constant factors and cache behavior
+picking a member of the category. Note that constant factors and cache behavior
can be a big deal. If you have a vector that usually only contains a few
elements (but could contain many), for example, it's much better to use
<a href="#dss_smallvector">SmallVector</a> than <a href="#dss_vector">vector</a>
consider a <a href="#dss_smallvector">SmallVector</a>). The cost of a heap
allocated array is the cost of the new/delete (aka malloc/free). Also note that
if you are allocating an array of a type with a constructor, the constructor and
-destructors will be run for every element in the array (resizable vectors only
+destructors will be run for every element in the array (re-sizable vectors only
construct those elements actually used).</p>
</div>
itself (which would waste space for elements that aren't in the container).
vector is also useful when interfacing with code that expects vectors :).
</p>
+
+<p>One worthwhile note about std::vector: avoid code like this:</p>
+
+<div class="doc_code">
+<pre>
+for ( ... ) {
+ std::vector<foo> V;
+ use V;
+}
+</pre>
+</div>
+
+<p>Instead, write this as:</p>
+
+<div class="doc_code">
+<pre>
+std::vector<foo> V;
+for ( ... ) {
+ use V;
+ V.clear();
+}
+</pre>
+</div>
+
+<p>Doing so will save (at least) one heap allocation and free per iteration of
+the loop.</p>
+
</div>
<!-- _______________________________________________________________________ -->
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="dss_other">Other options</a>
+ <a name="dss_other">Other Sequential Container options</a>
</div>
<div class="doc_text">
<div class="doc_text">
-<p>If you have a set-like datastructure that is usually small and whose elements
+<p>If you have a set-like data structure that is usually small and whose elements
are reasonably small, a <tt>SmallSet<Type, N></tt> is a good choice. This set
has space for N elements in place (thus, if the set is dynamically smaller than
-N, no malloc traffic is required) and access them with a simple linear search.
-When the set grows beyond 'N', it allocates a more expensive representation that
+N, no malloc traffic is required) and accesses them with a simple linear search.
+When the set grows beyond 'N' elements, it allocates a more expensive representation that
guarantees efficient access (for most types, it falls back to std::set, but for
-pointers it uses something far better, see <a
+pointers it uses something far better, <a
href="#dss_smallptrset">SmallPtrSet</a>).</p>
<p>The magic of this class is that it handles small sets extremely efficiently,
<div class="doc_text">
<p>SmallPtrSet has all the advantages of SmallSet (and a SmallSet of pointers is
-transparently implemented with a SmallPtrSet), but also suports iterators. If
-more than 'N' allocations are performed, a single quadratically
+transparently implemented with a SmallPtrSet), but also supports iterators. If
+more than 'N' insertions are performed, a single quadratically
probed hash table is allocated and grows as needed, providing extremely
efficient access (constant time insertion/deleting/queries with low constant
factors) and is very stingy with malloc traffic.</p>
FoldingSet is an aggregate class that is really good at uniquing
expensive-to-create or polymorphic objects. It is a combination of a chained
hash table with intrusive links (uniqued objects are required to inherit from
-FoldingSetNode) that uses SmallVector as part of its ID process.</p>
+FoldingSetNode) that uses <a href="#dss_smallvector">SmallVector</a> as part of
+its ID process.</p>
-<p>Consider a case where you want to implement a "getorcreate_foo" method for
+<p>Consider a case where you want to implement a "getOrCreateFoo" method for
a complex object (for example, a node in the code generator). The client has a
description of *what* it wants to generate (it knows the opcode and all the
operands), but we don't want to 'new' a node, then try inserting it into a set
-only to find out it already exists (at which point we would have to delete it
-and return the node that already exists).
+only to find out it already exists, at which point we would have to delete it
+and return the node that already exists.
</p>
<p>To support this style of client, FoldingSet perform a query with a
FoldingSetNodeID (which wraps SmallVector) that can be used to describe the
element that we want to query for. The query either returns the element
matching the ID or it returns an opaque ID that indicates where insertion should
-take place.</p>
+take place. Construction of the ID usually does not require heap traffic.</p>
<p>Because FoldingSet uses intrusive links, it can support polymorphic objects
in the set (for example, you can have SDNode instances mixed with LoadSDNodes).
<div class="doc_text">
-<p>std::set is a reasonable all-around set class, which is good at many things
-but great at nothing. std::set allocates memory for each element
+<p><tt>std::set</tt> is a reasonable all-around set class, which is decent at
+many things but great at nothing. std::set allocates memory for each element
inserted (thus it is very malloc intensive) and typically stores three pointers
-with every element (thus adding a large amount of per-element space overhead).
-It offers guaranteed log(n) performance, which is not particularly fast.
-</p>
+per element in the set (thus adding a large amount of per-element space
+overhead). It offers guaranteed log(n) performance, which is not particularly
+fast from a complexity standpoint (particularly if the elements of the set are
+expensive to compare, like strings), and has extremely high constant factors for
+lookup, insertion and removal.</p>
-<p>The advantages of std::set is that its iterators are stable (deleting or
+<p>The advantages of std::set are that its iterators are stable (deleting or
inserting an element from the set does not affect iterators or pointers to other
elements) and that iteration over the set is guaranteed to be in sorted order.
If the elements in the set are large, then the relative overhead of the pointers
</div>
<div class="doc_text">
-<p>LLVM's SetVector<Type> is actually a combination of a set along with
-a <a href="#ds_sequential">Sequential Container</a>. The important property
+<p>LLVM's SetVector<Type> is an adapter class that combines your choice of
+a set-like container along with a <a href="#ds_sequential">Sequential
+Container</a>. The important property
that this provides is efficient insertion with uniquing (duplicate elements are
ignored) with iteration support. It implements this by inserting elements into
both a set-like container and the sequential container, using the set-like
iteration is guaranteed to match the order of insertion into the SetVector.
This property is really important for things like sets of pointers. Because
pointer values are non-deterministic (e.g. vary across runs of the program on
-different machines), iterating over the pointers in a std::set or other set will
+different machines), iterating over the pointers in the set will
not be in a well-defined order.</p>
<p>
set and has the sum of constant factors from the set-like container and the
sequential container that it uses. Use it *only* if you need to iterate over
the elements in a deterministic order. SetVector is also expensive to delete
-elements out of (linear time).
+elements out of (linear time), unless you use it's "pop_back" method, which is
+faster.
</p>
+<p>SetVector is an adapter class that defaults to using std::vector and std::set
+for the underlying containers, so it is quite expensive. However,
+<tt>"llvm/ADT/SetVector.h"</tt> also provides a SmallSetVector class, which
+defaults to using a SmallVector and SmallSet of a specified size. If you use
+this, and if your sets are dynamically smaller than N, you will save a lot of
+heap traffic.</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="dss_uniquevector">"llvm/ADT/UniqueVector.h"</a>
+</div>
+
+<div class="doc_text">
+
+<p>
+UniqueVector is similar to <a href="#dss_setvector">SetVector</a>, but it
+retains a unique ID for each element inserted into the set. It internally
+contains a map and a vector, and it assigns a unique ID for each value inserted
+into the set.</p>
+
+<p>UniqueVector is very expensive: its cost is the sum of the cost of
+maintaining both the map and vector, it has high complexity, high constant
+factors, and produces a lot of malloc traffic. It should be avoided.</p>
+
</div>
+
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="dss_otherset">Other Options</a>
+ <a name="dss_otherset">Other Set-Like Container Options</a>
</div>
<div class="doc_text">
<p>
The STL provides several other options, such as std::multiset and the various
-"hash_set" like containers (whether from C++TR1 or from the SGI library).</p>
+"hash_set" like containers (whether from C++ TR1 or from the SGI library).</p>
<p>std::multiset is useful if you're not interested in elimination of
-duplicates, but has all the drawbacks of std::set. A sorted vector or some
-other approach is almost always better.</p>
+duplicates, but has all the drawbacks of std::set. A sorted vector (where you
+don't delete duplicate entries) or some other approach is almost always
+better.</p>
<p>The various hash_set implementations (exposed portably by
-"llvm/ADT/hash_set") is a standard chained hashtable. This algorithm is malloc
-intensive like std::set (performing an allocation for each element inserted,
+"llvm/ADT/hash_set") is a simple chained hashtable. This algorithm is as malloc
+intensive as std::set (performing an allocation for each element inserted,
thus having really high constant factors) but (usually) provides O(1)
insertion/deletion of elements. This can be useful if your elements are large
-(thus making the constant-factor cost relatively low). Element iteration does
-not visit elements in a useful order.</p>
+(thus making the constant-factor cost relatively low) or if comparisons are
+expensive. Element iteration does not visit elements in a useful order.</p>
</div>
</div>
<div class="doc_text">
-sorted vector
-std::map
-DenseMap
-UniqueVector
-IndexedMap
-hash_map
-CStringMap
+Map-like containers are useful when you want to associate data to a key. As
+usual, there are a lot of different ways to do this. :)
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="dss_sortedvectormap">A sorted 'vector'</a>
+</div>
+
+<div class="doc_text">
+
+<p>
+If your usage pattern follows a strict insert-then-query approach, you can
+trivially use the same approach as <a href="#dss_sortedvectorset">sorted vectors
+for set-like containers</a>. The only difference is that your query function
+(which uses std::lower_bound to get efficient log(n) lookup) should only compare
+the key, not both the key and value. This yields the same advantages as sorted
+vectors for sets.
+</p>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="dss_stringmap">"llvm/ADT/StringMap.h"</a>
+</div>
+
+<div class="doc_text">
+
+<p>
+Strings are commonly used as keys in maps, and they are difficult to support
+efficiently: they are variable length, inefficient to hash and compare when
+long, expensive to copy, etc. StringMap is a specialized container designed to
+cope with these issues. It supports mapping an arbitrary range of bytes to an
+arbitrary other object.</p>
+
+<p>The StringMap implementation uses a quadratically-probed hash table, where
+the buckets store a pointer to the heap allocated entries (and some other
+stuff). The entries in the map must be heap allocated because the strings are
+variable length. The string data (key) and the element object (value) are
+stored in the same allocation with the string data immediately after the element
+object. This container guarantees the "<tt>(char*)(&Value+1)</tt>" points
+to the key string for a value.</p>
+
+<p>The StringMap is very fast for several reasons: quadratic probing is very
+cache efficient for lookups, the hash value of strings in buckets is not
+recomputed when lookup up an element, StringMap rarely has to touch the
+memory for unrelated objects when looking up a value (even when hash collisions
+happen), hash table growth does not recompute the hash values for strings
+already in the table, and each pair in the map is store in a single allocation
+(the string data is stored in the same allocation as the Value of a pair).</p>
+
+<p>StringMap also provides query methods that take byte ranges, so it only ever
+copies a string if a value is inserted into the table.</p>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="dss_indexedmap">"llvm/ADT/IndexedMap.h"</a>
+</div>
+
+<div class="doc_text">
+<p>
+IndexedMap is a specialized container for mapping small dense integers (or
+values that can be mapped to small dense integers) to some other type. It is
+internally implemented as a vector with a mapping function that maps the keys to
+the dense integer range.
+</p>
+
+<p>
+This is useful for cases like virtual registers in the LLVM code generator: they
+have a dense mapping that is offset by a compile-time constant (the first
+virtual register ID).</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="dss_densemap">"llvm/ADT/DenseMap.h"</a>
+</div>
+
+<div class="doc_text">
+
+<p>
+DenseMap is a simple quadratically probed hash table. It excels at supporting
+small keys and values: it uses a single allocation to hold all of the pairs that
+are currently inserted in the map. DenseMap is a great way to map pointers to
+pointers, or map other small types to each other.
+</p>
+
+<p>
+There are several aspects of DenseMap that you should be aware of, however. The
+iterators in a densemap are invalidated whenever an insertion occurs, unlike
+map. Also, because DenseMap allocates space for a large number of key/value
+pairs (it starts with 64 by default), it will waste a lot of space if your keys
+or values are large. Finally, you must implement a partial specialization of
+DenseMapInfo for the key that you want, if it isn't already supported. This
+is required to tell DenseMap about two special marker values (which can never be
+inserted into the map) that it needs internally.</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="dss_map"><map></a>
+</div>
+
+<div class="doc_text">
+
+<p>
+std::map has similar characteristics to <a href="#dss_set">std::set</a>: it uses
+a single allocation per pair inserted into the map, it offers log(n) lookup with
+an extremely large constant factor, imposes a space penalty of 3 pointers per
+pair in the map, etc.</p>
+
+<p>std::map is most useful when your keys or values are very large, if you need
+to iterate over the collection in sorted order, or if you need stable iterators
+into the map (i.e. they don't get invalidated if an insertion or deletion of
+another element takes place).</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="dss_othermap">Other Map-Like Container Options</a>
+</div>
+
+<div class="doc_text">
+
+<p>
+The STL provides several other options, such as std::multimap and the various
+"hash_map" like containers (whether from C++ TR1 or from the SGI library).</p>
+
+<p>std::multimap is useful if you want to map a key to multiple values, but has
+all the drawbacks of std::map. A sorted vector or some other approach is almost
+always better.</p>
+
+<p>The various hash_map implementations (exposed portably by
+"llvm/ADT/hash_map") are simple chained hash tables. This algorithm is as
+malloc intensive as std::map (performing an allocation for each element
+inserted, thus having really high constant factors) but (usually) provides O(1)
+insertion/deletion of elements. This can be useful if your elements are large
+(thus making the constant-factor cost relatively low) or if comparisons are
+expensive. Element iteration does not visit elements in a useful order.</p>
+
</div>
<pre>
#include "<a href="/doxygen/InstIterator_8h-source.html">llvm/Support/InstIterator.h</a>"
-// <i>F is a ptr to a Function instance</i>
+// <i>F is a pointer to a Function instance</i>
for (inst_iterator i = inst_begin(F), e = inst_end(F); i != e; ++i)
llvm::cerr << *i << "\n";
</pre>
</div>
<p>Easy, isn't it? You can also use <tt>InstIterator</tt>s to fill a
-worklist with its initial contents. For example, if you wanted to
-initialize a worklist to contain all instructions in a <tt>Function</tt>
+work list with its initial contents. For example, if you wanted to
+initialize a work list to contain all instructions in a <tt>Function</tt>
F, all you would need to do is something like:</p>
<div class="doc_code">
certain function (i.e., some <tt>Function</tt>*) is already in scope. As you'll
learn later, you may want to use an <tt>InstVisitor</tt> to accomplish this in a
much more straight-forward manner, but this example will allow us to explore how
-you'd do it if you didn't have <tt>InstVisitor</tt> around. In pseudocode, this
+you'd do it if you didn't have <tt>InstVisitor</tt> around. In pseudo-code, this
is what we want to do:</p>
<div class="doc_code">
</div>
<p>will create an <tt>AllocaInst</tt> instance that represents the allocation of
-one integer in the current stack frame, at runtime. Each <tt>Instruction</tt>
+one integer in the current stack frame, at run time. Each <tt>Instruction</tt>
subclass is likely to have varying default parameters which change the semantics
of the instruction, so refer to the <a
href="/doxygen/classllvm_1_1Instruction.html">doxygen documentation for the subclass of
associated with the results of instructions! By supplying a value for the
<tt>Name</tt> (default) parameter of the <tt>Instruction</tt> constructor, you
associate a logical name with the result of the instruction's execution at
-runtime. For example, say that I'm writing a transformation that dynamically
+run time. For example, say that I'm writing a transformation that dynamically
allocates space for an integer on the stack, and that integer is going to be
used as some kind of index by some other code. To accomplish this, I place an
<tt>AllocaInst</tt> at the first point in the first <tt>BasicBlock</tt> of some
</div>
<p>where <tt>indexLoc</tt> is now the logical name of the instruction's
-execution value, which is a pointer to an integer on the runtime stack.</p>
+execution value, which is a pointer to an integer on the run time stack.</p>
<p><i>Inserting instructions</i></p>
</div>
+<!--_______________________________________________________________________-->
+<div class="doc_subsubsection">
+ <a name="schanges_deletingGV">Deleting <tt>GlobalVariable</tt>s</a>
+</div>
+
+<div class="doc_text">
+
+<p>Deleting a global variable from a module is just as easy as deleting an
+Instruction. First, you must have a pointer to the global variable that you wish
+ to delete. You use this pointer to erase it from its parent, the module.
+ For example:</p>
+
+<div class="doc_code">
+<pre>
+<a href="#GlobalVariable">GlobalVariable</a> *GV = .. ;
+
+GV->eraseFromParent();
+</pre>
+</div>
+
+</div>
+
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="advanced">Advanced Topics</a>
difficult to handle. Fortunately, for the most part, our implementation makes
most clients able to be completely unaware of the nasty internal details. The
primary case where clients are exposed to the inner workings of it are when
-building a recursive type. In addition to this case, the LLVM bytecode reader,
+building a recursive type. In addition to this case, the LLVM bitcode reader,
assembly parser, and linker also have to be aware of the inner workings of this
system.
</p>
<p>
Some data structures need more to perform more complex updates when types get
-resolved. The <a href="#SymbolTable">SymbolTable</a> class, for example, needs
-move and potentially merge type planes in its representation when a pointer
-changes.</p>
-
-<p>
-To support this, a class can derive from the AbstractTypeUser class. This class
+resolved. To support this, a class can derive from the AbstractTypeUser class.
+This class
allows it to get callbacks when certain types are resolved. To register to get
callbacks for a particular type, the DerivedType::{add/remove}AbstractTypeUser
methods can be called on a type. Note that these methods only work for <i>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="SymbolTable">The <tt>SymbolTable</tt> class</a>
+ <a name="SymbolTable">The <tt>ValueSymbolTable</tt> and
+ <tt>TypeSymbolTable</tt> classes</a>
</div>
<div class="doc_text">
-<p>This class provides a symbol table that the <a
+<p>The <tt><a href="http://llvm.org/doxygen/classllvm_1_1ValueSymbolTable.html">
+ValueSymbolTable</a></tt> class provides a symbol table that the <a
href="#Function"><tt>Function</tt></a> and <a href="#Module">
-<tt>Module</tt></a> classes use for naming definitions. The symbol table can
-provide a name for any <a href="#Value"><tt>Value</tt></a>.
-<tt>SymbolTable</tt> is an abstract data type. It hides the data it contains
-and provides access to it through a controlled interface.</p>
+<tt>Module</tt></a> classes use for naming value definitions. The symbol table
+can provide a name for any <a href="#Value"><tt>Value</tt></a>.
+The <tt><a href="http://llvm.org/doxygen/classllvm_1_1TypeSymbolTable.html">
+TypeSymbolTable</a></tt> class is used by the <tt>Module</tt> class to store
+names for types.</p>
<p>Note that the <tt>SymbolTable</tt> class should not be directly accessed
by most clients. It should only be used when iteration over the symbol table
an empty name) do not exist in the symbol table.
</p>
-<p>To use the <tt>SymbolTable</tt> well, you need to understand the
-structure of the information it holds. The class contains two
-<tt>std::map</tt> objects. The first, <tt>pmap</tt>, is a map of
-<tt>Type*</tt> to maps of name (<tt>std::string</tt>) to <tt>Value*</tt>.
-Thus, Values are stored in two-dimensions and accessed by <tt>Type</tt> and
-name.</p>
-
-<p>The interface of this class provides three basic types of operations:
-<ol>
- <li><em>Accessors</em>. Accessors provide read-only access to information
- such as finding a value for a name with the
- <a href="#SymbolTable_lookup">lookup</a> method.</li>
- <li><em>Mutators</em>. Mutators allow the user to add information to the
- <tt>SymbolTable</tt> with methods like
- <a href="#SymbolTable_insert"><tt>insert</tt></a>.</li>
- <li><em>Iterators</em>. Iterators allow the user to traverse the content
- of the symbol table in well defined ways, such as the method
- <a href="#SymbolTable_plane_begin"><tt>plane_begin</tt></a>.</li>
-</ol>
-
-<h3>Accessors</h3>
-<dl>
- <dt><tt>Value* lookup(const Type* Ty, const std::string& name) const</tt>:
- </dt>
- <dd>The <tt>lookup</tt> method searches the type plane given by the
- <tt>Ty</tt> parameter for a <tt>Value</tt> with the provided <tt>name</tt>.
- If a suitable <tt>Value</tt> is not found, null is returned.</dd>
-
- <dt><tt>bool isEmpty() const</tt>:</dt>
- <dd>This function returns true if both the value and types maps are
- empty</dd>
-</dl>
-
-<h3>Mutators</h3>
-<dl>
- <dt><tt>void insert(Value *Val)</tt>:</dt>
- <dd>This method adds the provided value to the symbol table. The Value must
- have both a name and a type which are extracted and used to place the value
- in the correct type plane under the value's name.</dd>
-
- <dt><tt>void insert(const std::string& Name, Value *Val)</tt>:</dt>
- <dd> Inserts a constant or type into the symbol table with the specified
- name. There can be a many to one mapping between names and constants
- or types.</dd>
-
- <dt><tt>void remove(Value* Val)</tt>:</dt>
- <dd> This method removes a named value from the symbol table. The
- type and name of the Value are extracted from \p N and used to
- lookup the Value in the correct type plane. If the Value is
- not in the symbol table, this method silently ignores the
- request.</dd>
-
- <dt><tt>Value* remove(const std::string& Name, Value *Val)</tt>:</dt>
- <dd> Remove a constant or type with the specified name from the
- symbol table.</dd>
-
- <dt><tt>Value *remove(const value_iterator& It)</tt>:</dt>
- <dd> Removes a specific value from the symbol table.
- Returns the removed value.</dd>
-
- <dt><tt>bool strip()</tt>:</dt>
- <dd> This method will strip the symbol table of its names leaving
- the type and values. </dd>
-
- <dt><tt>void clear()</tt>:</dt>
- <dd>Empty the symbol table completely.</dd>
-</dl>
-
-<h3>Iteration</h3>
-<p>The following functions describe three types of iterators you can obtain
-the beginning or end of the sequence for both const and non-const. It is
-important to keep track of the different kinds of iterators. There are
-three idioms worth pointing out:</p>
-
-<table>
- <tr><th>Units</th><th>Iterator</th><th>Idiom</th></tr>
- <tr>
- <td align="left">Planes Of name/Value maps</td><td>PI</td>
- <td align="left"><pre><tt>
-for (SymbolTable::plane_const_iterator PI = ST.plane_begin(),
- PE = ST.plane_end(); PI != PE; ++PI ) {
- PI->first // <i>This is the Type* of the plane</i>
- PI->second // <i>This is the SymbolTable::ValueMap of name/Value pairs</i>
-}
- </tt></pre></td>
- </tr>
- <tr>
- <td align="left">name/Value pairs in a plane</td><td>VI</td>
- <td align="left"><pre><tt>
-for (SymbolTable::value_const_iterator VI = ST.value_begin(SomeType),
- VE = ST.value_end(SomeType); VI != VE; ++VI ) {
- VI->first // <i>This is the name of the Value</i>
- VI->second // <i>This is the Value* value associated with the name</i>
-}
- </tt></pre></td>
- </tr>
-</table>
-
-<p>Using the recommended iterator names and idioms will help you avoid
-making mistakes. Of particular note, make sure that whenever you use
-value_begin(SomeType) that you always compare the resulting iterator
-with value_end(SomeType) not value_end(SomeOtherType) or else you
-will loop infinitely.</p>
-
-<dl>
-
- <dt><tt>plane_iterator plane_begin()</tt>:</dt>
- <dd>Get an iterator that starts at the beginning of the type planes.
- The iterator will iterate over the Type/ValueMap pairs in the
- type planes. </dd>
-
- <dt><tt>plane_const_iterator plane_begin() const</tt>:</dt>
- <dd>Get a const_iterator that starts at the beginning of the type
- planes. The iterator will iterate over the Type/ValueMap pairs
- in the type planes. </dd>
-
- <dt><tt>plane_iterator plane_end()</tt>:</dt>
- <dd>Get an iterator at the end of the type planes. This serves as
- the marker for end of iteration over the type planes.</dd>
-
- <dt><tt>plane_const_iterator plane_end() const</tt>:</dt>
- <dd>Get a const_iterator at the end of the type planes. This serves as
- the marker for end of iteration over the type planes.</dd>
+<p>These symbol tables support iteration over the values/types in the symbol
+table with <tt>begin/end/iterator</tt> and supports querying to see if a
+specific name is in the symbol table (with <tt>lookup</tt>). The
+<tt>ValueSymbolTable</tt> class exposes no public mutator methods, instead,
+simply call <tt>setName</tt> on a value, which will autoinsert it into the
+appropriate symbol table. For types, use the Module::addTypeName method to
+insert entries into the symbol table.</p>
- <dt><tt>value_iterator value_begin(const Type *Typ)</tt>:</dt>
- <dd>Get an iterator that starts at the beginning of a type plane.
- The iterator will iterate over the name/value pairs in the type plane.
- Note: The type plane must already exist before using this.</dd>
-
- <dt><tt>value_const_iterator value_begin(const Type *Typ) const</tt>:</dt>
- <dd>Get a const_iterator that starts at the beginning of a type plane.
- The iterator will iterate over the name/value pairs in the type plane.
- Note: The type plane must already exist before using this.</dd>
-
- <dt><tt>value_iterator value_end(const Type *Typ)</tt>:</dt>
- <dd>Get an iterator to the end of a type plane. This serves as the marker
- for end of iteration of the type plane.
- Note: The type plane must already exist before using this.</dd>
-
- <dt><tt>value_const_iterator value_end(const Type *Typ) const</tt>:</dt>
- <dd>Get a const_iterator to the end of a type plane. This serves as the
- marker for end of iteration of the type plane.
- Note: the type plane must already exist before using this.</dd>
-
- <dt><tt>plane_const_iterator find(const Type* Typ ) const</tt>:</dt>
- <dd>This method returns a plane_const_iterator for iteration over
- the type planes starting at a specific plane, given by \p Ty.</dd>
-
- <dt><tt>plane_iterator find( const Type* Typ </tt>:</dt>
- <dd>This method returns a plane_iterator for iteration over the
- type planes starting at a specific plane, given by \p Ty.</dd>
-
-</dl>
</div>
</dd>
<dt><tt>PointerType</tt></dt>
<dd>Subclass of SequentialType for pointer types.</dd>
- <dt><tt>PackedType</tt></dt>
- <dd>Subclass of SequentialType for packed (vector) types. A
- packed type is similar to an ArrayType but is distinguished because it is
- a first class type wherease ArrayType is not. Packed types are used for
+ <dt><tt>VectorType</tt></dt>
+ <dd>Subclass of SequentialType for vector types. A
+ vector type is similar to an ArrayType but is distinguished because it is
+ a first class type wherease ArrayType is not. Vector types are used for
vector operations and are usually small vectors of of an integer or floating
point type.</dd>
<dt><tt>StructType</tt></dt>
<dd>Subclass of DerivedTypes for struct types.</dd>
- <dt><tt>FunctionType</tt></dt>
+ <dt><tt><a name="FunctionType">FunctionType</a></tt></dt>
<dd>Subclass of DerivedTypes for function types.
<ul>
<li><tt>bool isVarArg() const</tt>: Returns true if its a vararg
</dl>
</div>
+
+
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="Value">The <tt>Value</tt> class</a>
+ <a name="Module">The <tt>Module</tt> class</a>
</div>
-<div>
-
-<p><tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt>
-<br>
-doxygen info: <a href="/doxygen/classllvm_1_1Value.html">Value Class</a></p>
-
-<p>The <tt>Value</tt> class is the most important class in the LLVM Source
-base. It represents a typed value that may be used (among other things) as an
-operand to an instruction. There are many different types of <tt>Value</tt>s,
-such as <a href="#Constant"><tt>Constant</tt></a>s,<a
-href="#Argument"><tt>Argument</tt></a>s. Even <a
-href="#Instruction"><tt>Instruction</tt></a>s and <a
-href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.</p>
-
-<p>A particular <tt>Value</tt> may be used many times in the LLVM representation
-for a program. For example, an incoming argument to a function (represented
-with an instance of the <a href="#Argument">Argument</a> class) is "used" by
-every instruction in the function that references the argument. To keep track
-of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
-href="#User"><tt>User</tt></a>s that is using it (the <a
-href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
-graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
-def-use information in the program, and is accessible through the <tt>use_</tt>*
-methods, shown below.</p>
-
-<p>Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed,
-and this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
-method. In addition, all LLVM values can be named. The "name" of the
-<tt>Value</tt> is a symbolic string printed in the LLVM code:</p>
-
-<div class="doc_code">
-<pre>
-%<b>foo</b> = add i32 1, 2
-</pre>
-</div>
+<div class="doc_text">
-<p><a name="#nameWarning">The name of this instruction is "foo".</a> <b>NOTE</b>
-that the name of any value may be missing (an empty string), so names should
-<b>ONLY</b> be used for debugging (making the source code easier to read,
-debugging printouts), they should not be used to keep track of values or map
-between them. For this purpose, use a <tt>std::map</tt> of pointers to the
-<tt>Value</tt> itself instead.</p>
+<p><tt>#include "<a
+href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt><br> doxygen info:
+<a href="/doxygen/classllvm_1_1Module.html">Module Class</a></p>
-<p>One important aspect of LLVM is that there is no distinction between an SSA
-variable and the operation that produces it. Because of this, any reference to
-the value produced by an instruction (or the value available as an incoming
-argument, for example) is represented as a direct pointer to the instance of
-the class that
-represents this value. Although this may take some getting used to, it
-simplifies the representation and makes it easier to manipulate.</p>
+<p>The <tt>Module</tt> class represents the top level structure present in LLVM
+programs. An LLVM module is effectively either a translation unit of the
+original program or a combination of several translation units merged by the
+linker. The <tt>Module</tt> class keeps track of a list of <a
+href="#Function"><tt>Function</tt></a>s, a list of <a
+href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
+href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
+helpful member functions that try to make common operations easy.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="m_Value">Important Public Members of the <tt>Value</tt> class</a>
+ <a name="m_Module">Important Public Members of the <tt>Module</tt> class</a>
</div>
<div class="doc_text">
<ul>
- <li><tt>Value::use_iterator</tt> - Typedef for iterator over the
-use-list<br>
- <tt>Value::use_const_iterator</tt> - Typedef for const_iterator over
-the use-list<br>
- <tt>unsigned use_size()</tt> - Returns the number of users of the
-value.<br>
- <tt>bool use_empty()</tt> - Returns true if there are no users.<br>
- <tt>use_iterator use_begin()</tt> - Get an iterator to the start of
-the use-list.<br>
- <tt>use_iterator use_end()</tt> - Get an iterator to the end of the
-use-list.<br>
- <tt><a href="#User">User</a> *use_back()</tt> - Returns the last
-element in the list.
- <p> These methods are the interface to access the def-use
-information in LLVM. As with all other iterators in LLVM, the naming
-conventions follow the conventions defined by the <a href="#stl">STL</a>.</p>
- </li>
- <li><tt><a href="#Type">Type</a> *getType() const</tt>
- <p>This method returns the Type of the Value.</p>
- </li>
- <li><tt>bool hasName() const</tt><br>
- <tt>std::string getName() const</tt><br>
- <tt>void setName(const std::string &Name)</tt>
- <p> This family of methods is used to access and assign a name to a <tt>Value</tt>,
-be aware of the <a href="#nameWarning">precaution above</a>.</p>
- </li>
- <li><tt>void replaceAllUsesWith(Value *V)</tt>
-
- <p>This method traverses the use list of a <tt>Value</tt> changing all <a
- href="#User"><tt>User</tt>s</a> of the current value to refer to
- "<tt>V</tt>" instead. For example, if you detect that an instruction always
- produces a constant value (for example through constant folding), you can
- replace all uses of the instruction with the constant like this:</p>
+ <li><tt>Module::Module(std::string name = "")</tt></li>
+</ul>
-<div class="doc_code">
-<pre>
-Inst->replaceAllUsesWith(ConstVal);
-</pre>
-</div>
+<p>Constructing a <a href="#Module">Module</a> is easy. You can optionally
+provide a name for it (probably based on the name of the translation unit).</p>
-</ul>
+<ul>
+ <li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
+ <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
+
+ <tt>begin()</tt>, <tt>end()</tt>
+ <tt>size()</tt>, <tt>empty()</tt>
+
+ <p>These are forwarding methods that make it easy to access the contents of
+ a <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
+ list.</p></li>
+
+ <li><tt>Module::FunctionListType &getFunctionList()</tt>
+
+ <p> Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
+ necessary to use when you need to update the list or perform a complex
+ action that doesn't have a forwarding method.</p>
+
+ <p><!-- Global Variable --></p></li>
+</ul>
+
+<hr>
+
+<ul>
+ <li><tt>Module::global_iterator</tt> - Typedef for global variable list iterator<br>
+
+ <tt>Module::const_global_iterator</tt> - Typedef for const_iterator.<br>
+
+ <tt>global_begin()</tt>, <tt>global_end()</tt>
+ <tt>global_size()</tt>, <tt>global_empty()</tt>
+
+ <p> These are forwarding methods that make it easy to access the contents of
+ a <tt>Module</tt> object's <a
+ href="#GlobalVariable"><tt>GlobalVariable</tt></a> list.</p></li>
+
+ <li><tt>Module::GlobalListType &getGlobalList()</tt>
+
+ <p>Returns the list of <a
+ href="#GlobalVariable"><tt>GlobalVariable</tt></a>s. This is necessary to
+ use when you need to update the list or perform a complex action that
+ doesn't have a forwarding method.</p>
+
+ <p><!-- Symbol table stuff --> </p></li>
+</ul>
+
+<hr>
+
+<ul>
+ <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt>
+
+ <p>Return a reference to the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
+ for this <tt>Module</tt>.</p>
+
+ <p><!-- Convenience methods --></p></li>
+</ul>
+
+<hr>
+
+<ul>
+ <li><tt><a href="#Function">Function</a> *getFunction(const std::string
+ &Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt>
+
+ <p>Look up the specified function in the <tt>Module</tt> <a
+ href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
+ <tt>null</tt>.</p></li>
+
+ <li><tt><a href="#Function">Function</a> *getOrInsertFunction(const
+ std::string &Name, const <a href="#FunctionType">FunctionType</a> *T)</tt>
+
+ <p>Look up the specified function in the <tt>Module</tt> <a
+ href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
+ external declaration for the function and return it.</p></li>
+
+ <li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt>
+
+ <p>If there is at least one entry in the <a
+ href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
+ href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
+ string.</p></li>
+
+ <li><tt>bool addTypeName(const std::string &Name, const <a
+ href="#Type">Type</a> *Ty)</tt>
+
+ <p>Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
+ mapping <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this
+ name, true is returned and the <a
+ href="#SymbolTable"><tt>SymbolTable</tt></a> is not modified.</p></li>
+</ul>
+
+</div>
-</div>
+
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="Value">The <tt>Value</tt> class</a>
+</div>
+
+<div class="doc_text">
+
+<p><tt>#include "<a href="/doxygen/Value_8h-source.html">llvm/Value.h</a>"</tt>
+<br>
+doxygen info: <a href="/doxygen/classllvm_1_1Value.html">Value Class</a></p>
+
+<p>The <tt>Value</tt> class is the most important class in the LLVM Source
+base. It represents a typed value that may be used (among other things) as an
+operand to an instruction. There are many different types of <tt>Value</tt>s,
+such as <a href="#Constant"><tt>Constant</tt></a>s,<a
+href="#Argument"><tt>Argument</tt></a>s. Even <a
+href="#Instruction"><tt>Instruction</tt></a>s and <a
+href="#Function"><tt>Function</tt></a>s are <tt>Value</tt>s.</p>
+
+<p>A particular <tt>Value</tt> may be used many times in the LLVM representation
+for a program. For example, an incoming argument to a function (represented
+with an instance of the <a href="#Argument">Argument</a> class) is "used" by
+every instruction in the function that references the argument. To keep track
+of this relationship, the <tt>Value</tt> class keeps a list of all of the <a
+href="#User"><tt>User</tt></a>s that is using it (the <a
+href="#User"><tt>User</tt></a> class is a base class for all nodes in the LLVM
+graph that can refer to <tt>Value</tt>s). This use list is how LLVM represents
+def-use information in the program, and is accessible through the <tt>use_</tt>*
+methods, shown below.</p>
+
+<p>Because LLVM is a typed representation, every LLVM <tt>Value</tt> is typed,
+and this <a href="#Type">Type</a> is available through the <tt>getType()</tt>
+method. In addition, all LLVM values can be named. The "name" of the
+<tt>Value</tt> is a symbolic string printed in the LLVM code:</p>
+
+<div class="doc_code">
+<pre>
+%<b>foo</b> = add i32 1, 2
+</pre>
+</div>
+
+<p><a name="nameWarning">The name of this instruction is "foo".</a> <b>NOTE</b>
+that the name of any value may be missing (an empty string), so names should
+<b>ONLY</b> be used for debugging (making the source code easier to read,
+debugging printouts), they should not be used to keep track of values or map
+between them. For this purpose, use a <tt>std::map</tt> of pointers to the
+<tt>Value</tt> itself instead.</p>
+
+<p>One important aspect of LLVM is that there is no distinction between an SSA
+variable and the operation that produces it. Because of this, any reference to
+the value produced by an instruction (or the value available as an incoming
+argument, for example) is represented as a direct pointer to the instance of
+the class that
+represents this value. Although this may take some getting used to, it
+simplifies the representation and makes it easier to manipulate.</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="m_Value">Important Public Members of the <tt>Value</tt> class</a>
+</div>
+
+<div class="doc_text">
+
+<ul>
+ <li><tt>Value::use_iterator</tt> - Typedef for iterator over the
+use-list<br>
+ <tt>Value::use_const_iterator</tt> - Typedef for const_iterator over
+the use-list<br>
+ <tt>unsigned use_size()</tt> - Returns the number of users of the
+value.<br>
+ <tt>bool use_empty()</tt> - Returns true if there are no users.<br>
+ <tt>use_iterator use_begin()</tt> - Get an iterator to the start of
+the use-list.<br>
+ <tt>use_iterator use_end()</tt> - Get an iterator to the end of the
+use-list.<br>
+ <tt><a href="#User">User</a> *use_back()</tt> - Returns the last
+element in the list.
+ <p> These methods are the interface to access the def-use
+information in LLVM. As with all other iterators in LLVM, the naming
+conventions follow the conventions defined by the <a href="#stl">STL</a>.</p>
+ </li>
+ <li><tt><a href="#Type">Type</a> *getType() const</tt>
+ <p>This method returns the Type of the Value.</p>
+ </li>
+ <li><tt>bool hasName() const</tt><br>
+ <tt>std::string getName() const</tt><br>
+ <tt>void setName(const std::string &Name)</tt>
+ <p> This family of methods is used to access and assign a name to a <tt>Value</tt>,
+be aware of the <a href="#nameWarning">precaution above</a>.</p>
+ </li>
+ <li><tt>void replaceAllUsesWith(Value *V)</tt>
+
+ <p>This method traverses the use list of a <tt>Value</tt> changing all <a
+ href="#User"><tt>User</tt>s</a> of the current value to refer to
+ "<tt>V</tt>" instead. For example, if you detect that an instruction always
+ produces a constant value (for example through constant folding), you can
+ replace all uses of the instruction with the constant like this:</p>
+
+<div class="doc_code">
+<pre>
+Inst->replaceAllUsesWith(ConstVal);
+</pre>
+</div>
+
+</ul>
+
+</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
+ <a name="Constant">The <tt>Constant</tt> class and subclasses</a>
</div>
<div class="doc_text">
-<p><tt>#include "<a
-href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt><br>
-doxygen info: <a href="/doxygen/structllvm_1_1BasicBlock.html">BasicBlock
-Class</a><br>
-Superclass: <a href="#Value"><tt>Value</tt></a></p>
-
-<p>This class represents a single entry multiple exit section of the code,
-commonly known as a basic block by the compiler community. The
-<tt>BasicBlock</tt> class maintains a list of <a
-href="#Instruction"><tt>Instruction</tt></a>s, which form the body of the block.
-Matching the language definition, the last element of this list of instructions
-is always a terminator instruction (a subclass of the <a
-href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).</p>
-
-<p>In addition to tracking the list of instructions that make up the block, the
-<tt>BasicBlock</tt> class also keeps track of the <a
-href="#Function"><tt>Function</tt></a> that it is embedded into.</p>
-
-<p>Note that <tt>BasicBlock</tt>s themselves are <a
-href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
-like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
-<tt>label</tt>.</p>
+<p>Constant represents a base class for different types of constants. It
+is subclassed by ConstantInt, ConstantArray, etc. for representing
+the various types of Constants. <a href="#GlobalValue">GlobalValue</a> is also
+a subclass, which represents the address of a global variable or function.
+</p>
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="m_BasicBlock">Important Public Members of the <tt>BasicBlock</tt>
- class</a>
-</div>
-
+<div class="doc_subsubsection">Important Subclasses of Constant </div>
<div class="doc_text">
-
<ul>
-
-<li><tt>BasicBlock(const std::string &Name = "", </tt><tt><a
- href="#Function">Function</a> *Parent = 0)</tt>
-
-<p>The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
-insertion into a function. The constructor optionally takes a name for the new
-block, and a <a href="#Function"><tt>Function</tt></a> to insert it into. If
-the <tt>Parent</tt> parameter is specified, the new <tt>BasicBlock</tt> is
-automatically inserted at the end of the specified <a
-href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
-manually inserted into the <a href="#Function"><tt>Function</tt></a>.</p></li>
-
-<li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
-<tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
-<tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
-<tt>size()</tt>, <tt>empty()</tt>
-STL-style functions for accessing the instruction list.
-
-<p>These methods and typedefs are forwarding functions that have the same
-semantics as the standard library methods of the same names. These methods
-expose the underlying instruction list of a basic block in a way that is easy to
-manipulate. To get the full complement of container operations (including
-operations to update the list), you must use the <tt>getInstList()</tt>
-method.</p></li>
-
-<li><tt>BasicBlock::InstListType &getInstList()</tt>
-
-<p>This method is used to get access to the underlying container that actually
-holds the Instructions. This method must be used when there isn't a forwarding
-function in the <tt>BasicBlock</tt> class for the operation that you would like
-to perform. Because there are no forwarding functions for "updating"
-operations, you need to use this if you want to update the contents of a
-<tt>BasicBlock</tt>.</p></li>
-
-<li><tt><a href="#Function">Function</a> *getParent()</tt>
-
-<p> Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
-embedded into, or a null pointer if it is homeless.</p></li>
-
-<li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt>
-
-<p> Returns a pointer to the terminator instruction that appears at the end of
-the <tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
-instruction in the block is not a terminator, then a null pointer is
-returned.</p></li>
-
+ <li>ConstantInt : This subclass of Constant represents an integer constant of
+ any width.
+ <ul>
+ <li><tt>const APInt& getValue() const</tt>: Returns the underlying
+ value of this constant, an APInt value.</li>
+ <li><tt>int64_t getSExtValue() const</tt>: Converts the underlying APInt
+ value to an int64_t via sign extension. If the value (not the bit width)
+ of the APInt is too large to fit in an int64_t, an assertion will result.
+ For this reason, use of this method is discouraged.</li>
+ <li><tt>uint64_t getZExtValue() const</tt>: Converts the underlying APInt
+ value to a uint64_t via zero extension. IF the value (not the bit width)
+ of the APInt is too large to fit in a uint64_t, an assertion will result.
+ For this reason, use of this method is discouraged.</li>
+ <li><tt>static ConstantInt* get(const APInt& Val)</tt>: Returns the
+ ConstantInt object that represents the value provided by <tt>Val</tt>.
+ The type is implied as the IntegerType that corresponds to the bit width
+ of <tt>Val</tt>.</li>
+ <li><tt>static ConstantInt* get(const Type *Ty, uint64_t Val)</tt>:
+ Returns the ConstantInt object that represents the value provided by
+ <tt>Val</tt> for integer type <tt>Ty</tt>.</li>
+ </ul>
+ </li>
+ <li>ConstantFP : This class represents a floating point constant.
+ <ul>
+ <li><tt>double getValue() const</tt>: Returns the underlying value of
+ this constant. </li>
+ </ul>
+ </li>
+ <li>ConstantArray : This represents a constant array.
+ <ul>
+ <li><tt>const std::vector<Use> &getValues() const</tt>: Returns
+ a vector of component constants that makeup this array. </li>
+ </ul>
+ </li>
+ <li>ConstantStruct : This represents a constant struct.
+ <ul>
+ <li><tt>const std::vector<Use> &getValues() const</tt>: Returns
+ a vector of component constants that makeup this array. </li>
+ </ul>
+ </li>
+ <li>GlobalValue : This represents either a global variable or a function. In
+ either case, the value is a constant fixed address (after linking).
+ </li>
</ul>
-
</div>
+
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="GlobalValue">The <tt>GlobalValue</tt> class</a>
create and what type of linkage the function should have. The <a
href="#FunctionType"><tt>FunctionType</tt></a> argument
specifies the formal arguments and return value for the function. The same
- <a href="#FunctionTypel"><tt>FunctionType</tt></a> value can be used to
+ <a href="#FunctionType"><tt>FunctionType</tt></a> value can be used to
create multiple functions. The <tt>Parent</tt> argument specifies the Module
in which the function is defined. If this argument is provided, the function
will automatically be inserted into that module's list of
</div>
+
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="Module">The <tt>Module</tt> class</a>
+ <a name="BasicBlock">The <tt>BasicBlock</tt> class</a>
</div>
<div class="doc_text">
<p><tt>#include "<a
-href="/doxygen/Module_8h-source.html">llvm/Module.h</a>"</tt><br> doxygen info:
-<a href="/doxygen/classllvm_1_1Module.html">Module Class</a></p>
+href="/doxygen/BasicBlock_8h-source.html">llvm/BasicBlock.h</a>"</tt><br>
+doxygen info: <a href="/doxygen/structllvm_1_1BasicBlock.html">BasicBlock
+Class</a><br>
+Superclass: <a href="#Value"><tt>Value</tt></a></p>
-<p>The <tt>Module</tt> class represents the top level structure present in LLVM
-programs. An LLVM module is effectively either a translation unit of the
-original program or a combination of several translation units merged by the
-linker. The <tt>Module</tt> class keeps track of a list of <a
-href="#Function"><tt>Function</tt></a>s, a list of <a
-href="#GlobalVariable"><tt>GlobalVariable</tt></a>s, and a <a
-href="#SymbolTable"><tt>SymbolTable</tt></a>. Additionally, it contains a few
-helpful member functions that try to make common operations easy.</p>
+<p>This class represents a single entry multiple exit section of the code,
+commonly known as a basic block by the compiler community. The
+<tt>BasicBlock</tt> class maintains a list of <a
+href="#Instruction"><tt>Instruction</tt></a>s, which form the body of the block.
+Matching the language definition, the last element of this list of instructions
+is always a terminator instruction (a subclass of the <a
+href="#TerminatorInst"><tt>TerminatorInst</tt></a> class).</p>
+
+<p>In addition to tracking the list of instructions that make up the block, the
+<tt>BasicBlock</tt> class also keeps track of the <a
+href="#Function"><tt>Function</tt></a> that it is embedded into.</p>
+
+<p>Note that <tt>BasicBlock</tt>s themselves are <a
+href="#Value"><tt>Value</tt></a>s, because they are referenced by instructions
+like branches and can go in the switch tables. <tt>BasicBlock</tt>s have type
+<tt>label</tt>.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="m_Module">Important Public Members of the <tt>Module</tt> class</a>
+ <a name="m_BasicBlock">Important Public Members of the <tt>BasicBlock</tt>
+ class</a>
</div>
<div class="doc_text">
-
-<ul>
- <li><tt>Module::Module(std::string name = "")</tt></li>
-</ul>
-
-<p>Constructing a <a href="#Module">Module</a> is easy. You can optionally
-provide a name for it (probably based on the name of the translation unit).</p>
-
-<ul>
- <li><tt>Module::iterator</tt> - Typedef for function list iterator<br>
- <tt>Module::const_iterator</tt> - Typedef for const_iterator.<br>
-
- <tt>begin()</tt>, <tt>end()</tt>
- <tt>size()</tt>, <tt>empty()</tt>
-
- <p>These are forwarding methods that make it easy to access the contents of
- a <tt>Module</tt> object's <a href="#Function"><tt>Function</tt></a>
- list.</p></li>
-
- <li><tt>Module::FunctionListType &getFunctionList()</tt>
-
- <p> Returns the list of <a href="#Function"><tt>Function</tt></a>s. This is
- necessary to use when you need to update the list or perform a complex
- action that doesn't have a forwarding method.</p>
-
- <p><!-- Global Variable --></p></li>
-</ul>
-
-<hr>
-
-<ul>
- <li><tt>Module::global_iterator</tt> - Typedef for global variable list iterator<br>
-
- <tt>Module::const_global_iterator</tt> - Typedef for const_iterator.<br>
-
- <tt>global_begin()</tt>, <tt>global_end()</tt>
- <tt>global_size()</tt>, <tt>global_empty()</tt>
-
- <p> These are forwarding methods that make it easy to access the contents of
- a <tt>Module</tt> object's <a
- href="#GlobalVariable"><tt>GlobalVariable</tt></a> list.</p></li>
-
- <li><tt>Module::GlobalListType &getGlobalList()</tt>
-
- <p>Returns the list of <a
- href="#GlobalVariable"><tt>GlobalVariable</tt></a>s. This is necessary to
- use when you need to update the list or perform a complex action that
- doesn't have a forwarding method.</p>
-
- <p><!-- Symbol table stuff --> </p></li>
-</ul>
-
-<hr>
-
<ul>
- <li><tt><a href="#SymbolTable">SymbolTable</a> *getSymbolTable()</tt>
- <p>Return a reference to the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
- for this <tt>Module</tt>.</p>
+<li><tt>BasicBlock(const std::string &Name = "", </tt><tt><a
+ href="#Function">Function</a> *Parent = 0)</tt>
- <p><!-- Convenience methods --></p></li>
-</ul>
+<p>The <tt>BasicBlock</tt> constructor is used to create new basic blocks for
+insertion into a function. The constructor optionally takes a name for the new
+block, and a <a href="#Function"><tt>Function</tt></a> to insert it into. If
+the <tt>Parent</tt> parameter is specified, the new <tt>BasicBlock</tt> is
+automatically inserted at the end of the specified <a
+href="#Function"><tt>Function</tt></a>, if not specified, the BasicBlock must be
+manually inserted into the <a href="#Function"><tt>Function</tt></a>.</p></li>
-<hr>
+<li><tt>BasicBlock::iterator</tt> - Typedef for instruction list iterator<br>
+<tt>BasicBlock::const_iterator</tt> - Typedef for const_iterator.<br>
+<tt>begin()</tt>, <tt>end()</tt>, <tt>front()</tt>, <tt>back()</tt>,
+<tt>size()</tt>, <tt>empty()</tt>
+STL-style functions for accessing the instruction list.
-<ul>
- <li><tt><a href="#Function">Function</a> *getFunction(const std::string
- &Name, const <a href="#FunctionType">FunctionType</a> *Ty)</tt>
+<p>These methods and typedefs are forwarding functions that have the same
+semantics as the standard library methods of the same names. These methods
+expose the underlying instruction list of a basic block in a way that is easy to
+manipulate. To get the full complement of container operations (including
+operations to update the list), you must use the <tt>getInstList()</tt>
+method.</p></li>
- <p>Look up the specified function in the <tt>Module</tt> <a
- href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, return
- <tt>null</tt>.</p></li>
+<li><tt>BasicBlock::InstListType &getInstList()</tt>
- <li><tt><a href="#Function">Function</a> *getOrInsertFunction(const
- std::string &Name, const <a href="#FunctionType">FunctionType</a> *T)</tt>
+<p>This method is used to get access to the underlying container that actually
+holds the Instructions. This method must be used when there isn't a forwarding
+function in the <tt>BasicBlock</tt> class for the operation that you would like
+to perform. Because there are no forwarding functions for "updating"
+operations, you need to use this if you want to update the contents of a
+<tt>BasicBlock</tt>.</p></li>
- <p>Look up the specified function in the <tt>Module</tt> <a
- href="#SymbolTable"><tt>SymbolTable</tt></a>. If it does not exist, add an
- external declaration for the function and return it.</p></li>
+<li><tt><a href="#Function">Function</a> *getParent()</tt>
- <li><tt>std::string getTypeName(const <a href="#Type">Type</a> *Ty)</tt>
+<p> Returns a pointer to <a href="#Function"><tt>Function</tt></a> the block is
+embedded into, or a null pointer if it is homeless.</p></li>
- <p>If there is at least one entry in the <a
- href="#SymbolTable"><tt>SymbolTable</tt></a> for the specified <a
- href="#Type"><tt>Type</tt></a>, return it. Otherwise return the empty
- string.</p></li>
+<li><tt><a href="#TerminatorInst">TerminatorInst</a> *getTerminator()</tt>
- <li><tt>bool addTypeName(const std::string &Name, const <a
- href="#Type">Type</a> *Ty)</tt>
+<p> Returns a pointer to the terminator instruction that appears at the end of
+the <tt>BasicBlock</tt>. If there is no terminator instruction, or if the last
+instruction in the block is not a terminator, then a null pointer is
+returned.</p></li>
- <p>Insert an entry in the <a href="#SymbolTable"><tt>SymbolTable</tt></a>
- mapping <tt>Name</tt> to <tt>Ty</tt>. If there is already an entry for this
- name, true is returned and the <a
- href="#SymbolTable"><tt>SymbolTable</tt></a> is not modified.</p></li>
</ul>
</div>
-<!-- ======================================================================= -->
-<div class="doc_subsection">
- <a name="Constant">The <tt>Constant</tt> class and subclasses</a>
-</div>
-
-<div class="doc_text">
-
-<p>Constant represents a base class for different types of constants. It
-is subclassed by ConstantInt, ConstantArray, etc. for representing
-the various types of Constants.</p>
-
-</div>
-
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="m_Constant">Important Public Methods</a>
-</div>
-<div class="doc_text">
-</div>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">Important Subclasses of Constant </div>
-<div class="doc_text">
-<ul>
- <li>ConstantInt : This subclass of Constant represents an integer constant of
- any width, including boolean (1 bit integer).
- <ul>
- <li><tt>int64_t getSExtValue() const</tt>: Returns the underlying value of
- this constant as a sign extended signed integer value.</li>
- <li><tt>uint64_t getZExtValue() const</tt>: Returns the underlying value
- of this constant as a zero extended unsigned integer value.</li>
- <li><tt>static ConstantInt* get(const Type *Ty, uint64_t Val)</tt>:
- Returns the ConstantInt object that represents the value provided by
- <tt>Val</tt> for integer type <tt>Ty</tt>.</li>
- </ul>
- </li>
- <li>ConstantFP : This class represents a floating point constant.
- <ul>
- <li><tt>double getValue() const</tt>: Returns the underlying value of
- this constant. </li>
- </ul>
- </li>
- <li>ConstantArray : This represents a constant array.
- <ul>
- <li><tt>const std::vector<Use> &getValues() const</tt>: Returns
- a vector of component constants that makeup this array. </li>
- </ul>
- </li>
- <li>ConstantStruct : This represents a constant struct.
- <ul>
- <li><tt>const std::vector<Use> &getValues() const</tt>: Returns
- a vector of component constants that makeup this array. </li>
- </ul>
- </li>
- <li>GlobalValue : This represents either a global variable or a function. In
- either case, the value is a constant fixed address (after linking).
- </li>
-</ul>
-</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="Argument">The <tt>Argument</tt> class</a>
projects / oota-llvm.git / blobdiff