</ol>
<div class="doc_author">
- <p>Written by <a href="http://misha.brukman.net">Misha Brukman</a></p>
+ <p>Written by <a href="http://misha.brukman.net">Misha Brukman</a>,
+ Brad Jones, and <a href="http://nondot.org/sabre">Chris Lattner</a></p>
</div>
<!-- *********************************************************************** -->
someone else is already working on it. You will save yourself a lot of time and
effort by doing so.</p>
-<p>Finally, these are my notes, and since my extensions are not complete, I may
-be missing steps. If you find some omissions, please let me know <a
-href="http://misha.brukman.net/contact.html">directly</a> or post on <a
-href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM-dev</a>.</p>
-
</div>
<!-- *********************************************************************** -->
<li><tt>llvm/include/llvm/Intrinsics.h</tt>:
add an enum in the <tt>llvm::Intrinsic</tt> namespace</li>
-<li><tt>llvm/lib/VMCore/IntrinsicLowering.cpp</tt>:
- implement the lowering for this intrinsic</li>
-
<li><tt>llvm/lib/VMCore/Verifier.cpp</tt>:
Add code to check the invariants of the intrinsic are respected.</li>
that you added.</li>
<li><tt>llvm/lib/Analysis/BasicAliasAnalysis.cpp</tt>: If the new intrinsic does
- not access memory, or does not write to memory, add it to the relevant list
+ not access memory or does not write to memory, add it to the relevant list
of functions.</li>
<li><tt>llvm/lib/Transforms/Utils/Local.cpp</tt>: If it is possible to constant
- propagate your intrinsic, add support to it in the
- <tt>canConstantFoldCallTo</tt> and <tt>ConstantFoldCall</tt> functions.</li>
+fold your intrinsic, add support to it in the <tt>canConstantFoldCallTo</tt> and
+<tt>ConstantFoldCall</tt> functions.</li>
<li>Test your intrinsic</li>
-<li><tt>llvm/test/Regression/*</tt>: add your test cases to the test suite.</li>
+
+<li><tt>llvm/test/Regression/*</tt>: add your test cases to the test suite</li>
</ol>
-<p>If this intrinsic requires code generator support (ie, it cannot be lowered).
-You should also add support to the code generator in question.</p>
+<p>Once the intrinsic has been added to the system, you must add code generator
+support for it. Generally you must do the following steps:</p>
+
+<dl>
+<dt>Add support to the C backend in <tt>lib/Target/CBackend/</tt></dt>
+
+<dd>Depending on the intrinsic, there are a few ways to implement this. First,
+if it makes sense to lower the intrinsic to an expanded sequence of C code in
+all cases, just emit the expansion in <tt>visitCallInst</tt>. Second, if the
+intrinsic has some way to express it with GCC (or any other compiler)
+extensions, it can be conditionally supported based on the compiler compiling
+the CBE output (see llvm.prefetch for an example). Third, if the intrinsic
+really has no way to be lowered, just have the code generator emit code that
+prints an error message and calls abort if executed.
+</dd>
+
+<dt>Add a enum value for the SelectionDAG node in
+<tt>include/llvm/CodeGen/SelectionDAGNodes.h</tt></dt>
+
+<dd>Also, add code to <tt>lib/CodeGen/SelectionDAG/SelectionDAG.cpp</tt> (and
+<tt>SelectionDAGPrinter.cpp</tt>) to print the node.</dd>
+
+<dt>Add code to <tt>SelectionDAG/SelectionDAGISel.cpp</tt> to recognize the
+intrinsic.</dt>
+
+<dd>Presumably the intrinsic should be recognized and turned into the node you
+added above.</dd>
+
+<dt>Add code to <tt>SelectionDAG/LegalizeDAG.cpp</tt> to <a
+href="CodeGenerator.html#selectiondag_legalize">legalize, promote, and
+expand</a> the node as necessary.</dt>
+
+<dd>If the intrinsic can be expanded to primitive operations, legalize can break
+the node down into other elementary operations that are be supported.</dd>
+
+<dt>Add target-specific support to specific code generators.</dt>
+
+<dd>Extend the code generators you are interested in to recognize and support
+the node, emitting the code you want.</dd>
+</dl>
+
+<p>
+Unfortunately, the process of extending the code generator to support a new node
+is not extremely well documented. As such, it is often helpful to look at other
+intrinsics (e.g. <tt>llvm.ctpop</tt>) to see how they are recognized and turned
+into a node by <tt>SelectionDAGISel.cpp</tt>, legalized by
+<tt>LegalizeDAG.cpp</tt>, then finally emitted by the various code generators.
+</p>
</div>
<li><tt>llvm/include/llvm/Instruction.def</tt>:
add a number for your instruction and an enum name</li>
-<li><tt>llvm/include/llvm/i*.h</tt>:
+<li><tt>llvm/include/llvm/Instructions.h</tt>:
add a definition for the class that will represent your instruction</li>
<li><tt>llvm/include/llvm/Support/InstVisitor.h</tt>:
add the grammar on how your instruction can be read and what it will
construct as a result</li>
-<li><tt>llvm/lib/Bytecode/Reader/InstructionReader.cpp</tt>:
+<li><tt>llvm/lib/Bytecode/Reader/Reader.cpp</tt>:
add a case for your instruction and how it will be parsed from bytecode</li>
<li><tt>llvm/lib/VMCore/Instruction.cpp</tt>:
add a case for how your instruction will be printed out to assembly</li>
-<li><tt>llvm/lib/VMCore/i*.cpp</tt>:
- implement the class you defined in <tt>llvm/include/llvm/i*.h</tt></li>
+<li><tt>llvm/lib/VMCore/Instructions.cpp</tt>:
+ implement the class you defined in
+ <tt>llvm/include/llvm/Instructions.h</tt></li>
+
+<li>Test your instruction</li>
+
+<li><tt>llvm/lib/Target/*</tt>:
+ Add support for your instruction to code generators, or add a lowering
+ pass.</li>
+
+<li><tt>llvm/test/Regression/*</tt>: add your test cases to the test suite.</li>
</ol>
<ol>
-<li><tt>llvm/include/llvm/Type.def</tt>:
- add enum for the type</li>
-
<li><tt>llvm/include/llvm/Type.h</tt>:
- add ID number for the new type; add static <tt>Type*</tt> for this type</li>
+ add enum for the new type; add static <tt>Type*</tt> for this type</li>
<li><tt>llvm/lib/VMCore/Type.cpp</tt>:
add mapping from <tt>TypeID</tt> => <tt>Type*</tt>;
<div class="doc_text">
-<p>TODO</p>
+<ol>
+<li><tt>llvm/include/llvm/Type.h</tt>:
+ add enum for the new type; add a forward declaration of the type
+ also</li>
+
+<li><tt>llvm/include/llvm/DerivedTypes.h</tt>:
+ add new class to represent new class in the hierarchy; add forward
+ declaration to the TypeMap value type</li>
+
+<li><tt>llvm/lib/VMCore/Type.cpp</tt>:
+ add support for derived type to:
+<div class="doc_code">
+<pre>
+std::string getTypeDescription(const Type &Ty,
+ std::vector<const Type*> &TypeStack)
+bool TypesEqual(const Type *Ty, const Type *Ty2,
+ std::map<const Type*, const Type*> & EqTypes)
+</pre>
+</div>
+ add necessary member functions for type, and factory methods</li>
+
+<li><tt>llvm/lib/AsmReader/Lexer.l</tt>:
+ add ability to parse in the type from text assembly</li>
+
+<li><tt>llvm/lib/ByteCode/Writer/Writer.cpp</tt>:
+ modify <tt>void BytecodeWriter::outputType(const Type *T)</tt> to serialize
+ your type</li>
+
+<li><tt>llvm/lib/ByteCode/Reader/Reader.cpp</tt>:
+ modify <tt>const Type *BytecodeReader::ParseType()</tt> to read your data
+ type</li>
+
+<li><tt>llvm/lib/VMCore/AsmWriter.cpp</tt>:
+ modify
+<div class="doc_code">
+<pre>
+void calcTypeName(const Type *Ty,
+ std::vector<const Type*> &TypeStack,
+ std::map<const Type*,std::string> &TypeNames,
+ std::string & Result)
+</pre>
+</div>
+ to output the new derived type
+</li>
+
+
+</ol>
</div>
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