[llvm-commits] CVS: llvm/docs/ExtendingLLVM.html llvm.css
Misha Brukman
brukman at cs.uiuc.edu
Mon Apr 5 22:54:01 PDT 2004
Changes in directory llvm/docs:
ExtendingLLVM.html added (r1.1)
llvm.css updated: 1.11 -> 1.12
---
Log message:
Added notes on extending LLVM with new instructions, intrinsics, types, etc.
---
Diffs of the changes: (+214 -0)
Index: llvm/docs/ExtendingLLVM.html
diff -c /dev/null llvm/docs/ExtendingLLVM.html:1.1
*** /dev/null Mon Apr 5 22:53:59 2004
--- llvm/docs/ExtendingLLVM.html Mon Apr 5 22:53:49 2004
***************
*** 0 ****
--- 1,213 ----
+ <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
+ "http://www.w3.org/TR/html4/strict.dtd">
+ <html>
+ <head>
+ <title>Extending LLVM: Adding instructions, intrinsics, types, etc.</title>
+ <link rel="stylesheet" href="llvm.css" type="text/css">
+ </head>
+
+ <body>
+
+ <div class="doc_title">
+ Extending LLVM: Adding instructions, intrinsics, types, etc.
+ </div>
+
+ <ol>
+ <li><a href="#introduction">Introduction and Warning</a></li>
+ <li><a href="#instruction">Adding a new instruction</a></li>
+ <li><a href="#intrinsic">Adding a new intrinsic function</a></li>
+ <li><a href="#type">Adding a new type</a>
+ <ol>
+ <li><a href="#fund_type">Adding a new fundamental type</a></li>
+ <li><a href="#derived_type">Adding a new derived type</a></li>
+ </ol></li>
+ </ol>
+
+ <div class="doc_text">
+ <p><b>Written by <a href="http://misha.brukman.net">Misha Brukman</a></b></p>
+ </div>
+
+ <!-- *********************************************************************** -->
+ <div class="doc_section">
+ <a name="introduction">Introduction and Warning</a>
+ </div>
+ <!-- *********************************************************************** -->
+
+ <div class="doc_text">
+
+ <p>During the course of using LLVM, you may wish to customize it for your
+ research project or for experimentation. At this point, you may realize that
+ you need to add something to LLVM, whether it be a new fundamental type, a new
+ intrinsic function, or a whole new instruction.</p>
+
+ <p>When you come to this realization, stop and think. Do you really need to
+ extend LLVM? Is it a new fundamental capability that LLVM does not support at
+ its current incarnation or can it be synthesized from already pre-existing LLVM
+ elements? If you are not sure, ask on the <a
+ href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM-dev</a> list. The
+ reason is that extending LLVM will get involved as you need to update all the
+ different passes that you intend to use with your extension, and there are
+ <em>many</em> LLVM analyses and transformations, so it may be quite a bit of
+ work.</p>
+
+ <p>Before you invest a significant amount of effort into a non-trivial
+ extension, <span class="doc_warning">ask on the list</span> if what you are
+ looking to do can be done with already-existing infrastructure, or if maybe
+ 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>
+
+ <!-- *********************************************************************** -->
+ <div class="doc_section">
+ <a name="instruction">Adding a new instruction</a>
+ </div>
+ <!-- *********************************************************************** -->
+
+ <div class="doc_text">
+
+ <p><span class="doc_warning">WARNING: adding instructions changes the bytecode
+ format, and will break compatibility with currently-existing LLVM
+ installations.</span> Only add an instruction if it is absolutely
+ necessary.</p>
+
+ <ol>
+ <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>:
+ add a definition for the class that will represent your instruction</li>
+
+ <li><tt>llvm/include/llvm/Support/InstVisitor.h</tt>:
+ add a prototype for a visitor to your new instruction type</li>
+
+ <li><tt>llvm/lib/AsmParser/Lexer.l</tt>:
+ add a new token to parse your instruction from assembly text file</li>
+
+ <li><tt>llvm/lib/AsmParser/llvmAsmParser.y</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>:
+ 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>
+
+ </ol>
+
+ <p>Also, you need to implement (or modify) any analyses or passes that you want
+ to understand this new instruction.</p>
+
+ </div>
+
+ <!-- *********************************************************************** -->
+ <div class="doc_section">
+ <a name="intrinsic">Adding a new intrinsic function</a>
+ </div>
+ <!-- *********************************************************************** -->
+
+ <div class="doc_text">
+
+ <p>Adding an intrinsic function is easier than adding an instruction, and is
+ transparent to optimization passes which treat it as an unanalyzable function.
+ If your added functionality can be expressed as a function call, an intrinsic
+ function is the method of choice for LLVM extension.</p>
+
+ <ol>
+
+ <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>:
+ handle the new intrinsic</li>
+
+ <li><tt>llvm/lib/VMCore/Function.cpp</tt>:
+ handle the new intrinsic</li>
+
+ </ol>
+
+ </div>
+
+ <!-- *********************************************************************** -->
+ <div class="doc_section">
+ <a name="type">Adding a new type</a>
+ </div>
+ <!-- *********************************************************************** -->
+
+ <div class="doc_text">
+
+ <p><span class="doc_warning">WARNING: adding new types changes the bytecode
+ format, and will break compatibility with currently-existing LLVM
+ installations.</span> Only add new types if it is absolutely necessary.</p>
+
+ </div>
+
+ <!-- ======================================================================= -->
+ <div class="doc_subsection">
+ <a name="fund_type">Adding a fundamental type</a>
+ </div>
+
+ <div class="doc_text">
+
+ <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>
+
+ <li><tt>llvm/lib/VMCore/Type.cpp</tt>:
+ add mapping from <tt>TypeID</tt> => <tt>Type*</tt>;
+ initialize the static <tt>Type*</tt></li>
+
+ <li><tt>llvm/lib/AsmReader/Lexer.l</tt>:
+ add ability to parse in the type from text assembly</li>
+
+ <li><tt>llvm/lib/AsmReader/llvmAsmParser.y</tt>:
+ add a token for that type</li>
+
+ </ol>
+
+ </div>
+
+ <!-- ======================================================================= -->
+ <div class="doc_subsection">
+ <a name="derived_type">Adding a derived type</a>
+ </div>
+
+ <div class="doc_text">
+
+ <p>TODO</p>
+
+ </div>
+
+ <!-- *********************************************************************** -->
+
+ <hr>
+ <address>
+ <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
+ src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
+ <a href="http://validator.w3.org/check/referer"><img
+ src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
+
+ <a href="http://misha.brukman.net">Misha Brukman</a><br>
+ <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
+ <br>
+ Last modified: $Date: 2004/04/06 03:53:49 $
+ </address>
+
+ </body>
+ </html>
Index: llvm/docs/llvm.css
diff -u llvm/docs/llvm.css:1.11 llvm/docs/llvm.css:1.12
--- llvm/docs/llvm.css:1.11 Wed Jan 14 18:13:59 2004
+++ llvm/docs/llvm.css Mon Apr 5 22:53:49 2004
@@ -50,3 +50,4 @@
.doc_table { text-align: center; width: 90%;
padding: 1px 1px 1px 1px; border: 1px; }
+.doc_warning { color: red; font-weight: bold }
More information about the llvm-commits
mailing list