+
+
+<p>In addition, many APIs have changed in this release. Some of the major LLVM
+API changes are:</p>
+
+<ul>
+<li>All uses of <tt>hash_set</tt> and <tt>hash_map</tt> have been removed from
+ the LLVM tree and the wrapper headers have been removed.</li>
+<li>The llvm/Streams.h and <tt>DOUT</tt> member of Debug.h have been removed. The
+ <tt>llvm::Ostream</tt> class has been completely removed and replaced with
+ uses of <tt>raw_ostream</tt>.</li>
+<li>LLVM's global uniquing tables for <tt>Type</tt>s and <tt>Constant</tt>s have
+ been privatized into members of an <tt>LLVMContext</tt>. A number of APIs
+ now take an <tt>LLVMContext</tt> as a parameter. To smooth the transition
+ for clients that will only ever use a single context, the new
+ <tt>getGlobalContext()</tt> API can be used to access a default global
+ context which can be passed in any and all cases where a context is
+ required.
+<li>The <tt>getABITypeSize</tt> methods are now called <tt>getAllocSize</tt>.</li>
+<li>The <tt>Add</tt>, <tt>Sub</tt> and <tt>Mul</tt> operators are no longer
+ overloaded for floating-point types. Floating-point addition, subtraction
+ and multiplication are now represented with new operators <tt>FAdd</tt>,
+ <tt>FSub</tt> and <tt>FMul</tt>. In the <tt>IRBuilder</tt> API,
+ <tt>CreateAdd</tt>, <tt>CreateSub</tt>, <tt>CreateMul</tt> and
+ <tt>CreateNeg</tt> should only be used for integer arithmetic now;
+ <tt>CreateFAdd</tt>, <tt>CreateFSub</tt>, <tt>CreateFMul</tt> and
+ <tt>CreateFNeg</tt> should now be used for floating-point arithmetic.</li>
+<li>The <tt>DynamicLibrary</tt> class can no longer be constructed, its functionality has
+ moved to static member functions.</li>
+<li><tt>raw_fd_ostream</tt>'s constructor for opening a given filename now
+ takes an extra <tt>Force</tt> argument. If <tt>Force</tt> is set to
+ <tt>false</tt>, an error will be reported if a file with the given name
+ already exists. If <tt>Force</tt> is set to <tt>true</tt>, the file will
+ be silently truncated (which is the behavior before this flag was
+ added).</li>
+<li><tt>SCEVHandle</tt> no longer exists, because reference counting is no
+ longer done for <tt>SCEV*</tt> objects, instead <tt>const SCEV*</tt>
+ should be used.</li>
+
+<li>Many APIs, notably <tt>llvm::Value</tt>, now use the <tt>StringRef</tt>
+and <tt>Twine</tt> classes instead of passing <tt>const char*</tt>
+or <tt>std::string</tt>, as described in
+the <a href="ProgrammersManual.html#string_apis">Programmer's Manual</a>. Most
+clients should be unaffected by this transition, unless they are used to
+<tt>Value::getName()</tt> returning a string. Here are some tips on updating to
+2.6:
+ <ul>
+ <li><tt>getNameStr()</tt> is still available, and matches the old
+ behavior. Replacing <tt>getName()</tt> calls with this is an safe option,
+ although more efficient alternatives are now possible.</li>
+
+ <li>If you were just relying on <tt>getName()</tt> being able to be sent to
+ a <tt>std::ostream</tt>, consider migrating
+ to <tt>llvm::raw_ostream</tt>.</li>
+
+ <li>If you were using <tt>getName().c_str()</tt> to get a <tt>const
+ char*</tt> pointer to the name, you can use <tt>getName().data()</tt>.
+ Note that this string (as before), may not be the entire name if the
+ name contains embedded null characters.</li>
+
+ <li>If you were using <tt>operator +</tt> on the result of <tt>getName()</tt> and
+ treating the result as an <tt>std::string</tt>, you can either
+ use <tt>Twine::str</tt> to get the result as an <tt>std::string</tt>, or
+ could move to a <tt>Twine</tt> based design.</li>
+
+ <li><tt>isName()</tt> should be replaced with comparison
+ against <tt>getName()</tt> (this is now efficient).
+ </ul>
+</li>
+
+<li>The registration interfaces for backend Targets has changed (what was
+previously <tt>TargetMachineRegistry</tt>). For backend authors, see the <a
+href="WritingAnLLVMBackend.html#TargetRegistration">Writing An LLVM Backend</a>
+guide. For clients, the notable API changes are:
+ <ul>
+ <li><tt>TargetMachineRegistry</tt> has been renamed
+ to <tt>TargetRegistry</tt>.</li>
+
+ <li>Clients should move to using the <tt>TargetRegistry::lookupTarget()</tt>
+ function to find targets.</li>
+ </ul>
+</li>
+</ul>
+