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author | NAKAMURA Takumi <geek4civic@gmail.com> | 2011-04-23 00:30:22 +0000 |
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committer | NAKAMURA Takumi <geek4civic@gmail.com> | 2011-04-23 00:30:22 +0000 |
commit | f5af6ada3b0570db1afc19029cad8fb8320676ef (patch) | |
tree | 4df12ad7fe5c5902fd8601d164291a94fa078f10 /docs/GarbageCollection.html | |
parent | 624dc1d4abf26a3ccd474f85a39058a99a9053ca (diff) | |
download | external_llvm-f5af6ada3b0570db1afc19029cad8fb8320676ef.zip external_llvm-f5af6ada3b0570db1afc19029cad8fb8320676ef.tar.gz external_llvm-f5af6ada3b0570db1afc19029cad8fb8320676ef.tar.bz2 |
docs: Introduce cascading style <div> and <p> continued on <h[2-5]>.
<h2>Section Example</h2>
<div> <!-- h2+div is applied -->
<p>Section preamble.</p>
<h3>Subsection Example</h3>
<p> <!-- h3+p is applied -->
Subsection body
</p>
<!-- End of section body -->
</div>
FIXME: Care H5 better.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130040 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/GarbageCollection.html')
-rw-r--r-- | docs/GarbageCollection.html | 59 |
1 files changed, 29 insertions, 30 deletions
diff --git a/docs/GarbageCollection.html b/docs/GarbageCollection.html index aa83a2d..761e1d0 100644 --- a/docs/GarbageCollection.html +++ b/docs/GarbageCollection.html @@ -84,7 +84,7 @@ </h2> <!-- *********************************************************************** --> -<div class="doc_text"> +<div> <p>Garbage collection is a widely used technique that frees the programmer from having to know the lifetimes of heap objects, making software easier to produce @@ -124,14 +124,12 @@ techniques dominates any low-level losses.</p> <p>This document describes the mechanisms and interfaces provided by LLVM to support accurate garbage collection.</p> -</div> - <!-- ======================================================================= --> <h3> <a name="feature">Goals and non-goals</a> </h3> -<div class="doc_text"> +<div> <p>LLVM's intermediate representation provides <a href="#intrinsics">garbage collection intrinsics</a> that offer support for a broad class of @@ -198,13 +196,15 @@ compiler matures.</p> </div> +</div> + <!-- *********************************************************************** --> <h2> <a name="quickstart">Getting started</a> </h2> <!-- *********************************************************************** --> -<div class="doc_text"> +<div> <p>Using a GC with LLVM implies many things, for example:</p> @@ -246,14 +246,12 @@ compiler matures.</p> includes a highly portable, built-in ShadowStack code generator. It is compiled into <tt>llc</tt> and works even with the interpreter and C backends.</p> -</div> - <!-- ======================================================================= --> <h3> <a name="quickstart-compiler">In your compiler</a> </h3> -<div class="doc_text"> +<div> <p>To turn the shadow stack on for your functions, first call:</p> @@ -280,7 +278,7 @@ switching to a more advanced GC.</p> <a name="quickstart-runtime">In your runtime</a> </h3> -<div class="doc_text"> +<div> <p>The shadow stack doesn't imply a memory allocation algorithm. A semispace collector or building atop <tt>malloc</tt> are great places to start, and can @@ -347,7 +345,7 @@ void visitGCRoots(void (*Visitor)(void **Root, const void *Meta)) { <a name="shadow-stack">About the shadow stack</a> </h3> -<div class="doc_text"> +<div> <p>Unlike many GC algorithms which rely on a cooperative code generator to compile stack maps, this algorithm carefully maintains a linked list of stack @@ -372,13 +370,15 @@ in order to improve performance.</p> </div> +</div> + <!-- *********************************************************************** --> <h2> <a name="core">IR features</a><a name="intrinsics"></a> </h2> <!-- *********************************************************************** --> -<div class="doc_text"> +<div> <p>This section describes the garbage collection facilities provided by the <a href="LangRef.html">LLVM intermediate representation</a>. The exact behavior @@ -390,8 +390,6 @@ intended to be a complete interface to any garbage collector. A program will need to interface with the GC library using the facilities provided by that program.</p> -</div> - <!-- ======================================================================= --> <h3> <a name="gcattr">Specifying GC code generation: <tt>gc "..."</tt></a> @@ -401,7 +399,7 @@ program.</p> define <i>ty</i> @<i>name</i>(...) <span style="text-decoration: underline">gc "<i>name</i>"</span> { ... </tt></div> -<div class="doc_text"> +<div> <p>The <tt>gc</tt> function attribute is used to specify the desired GC style to the compiler. Its programmatic equivalent is the <tt>setGC</tt> method of @@ -426,7 +424,7 @@ programs that use different garbage collection algorithms (or none at all).</p> void @llvm.gcroot(i8** %ptrloc, i8* %metadata) </tt></div> -<div class="doc_text"> +<div> <p>The <tt>llvm.gcroot</tt> intrinsic is used to inform LLVM that a stack variable references an object on the heap and is to be tracked for garbage @@ -498,7 +496,7 @@ CodeBlock: <a name="barriers">Reading and writing references in the heap</a> </h3> -<div class="doc_text"> +<div> <p>Some collectors need to be informed when the mutator (the program that needs garbage collection) either reads a pointer from or writes a pointer to a field @@ -534,8 +532,6 @@ require the corresponding barrier. Such a GC plugin will replace the intrinsic calls with the corresponding <tt>load</tt> or <tt>store</tt> instruction if they are used.</p> -</div> - <!-- ======================================================================= --> <h4> <a name="gcwrite">Write barrier: <tt>llvm.gcwrite</tt></a> @@ -545,7 +541,7 @@ are used.</p> void @llvm.gcwrite(i8* %value, i8* %object, i8** %derived) </tt></div> -<div class="doc_text"> +<div> <p>For write barriers, LLVM provides the <tt>llvm.gcwrite</tt> intrinsic function. It has exactly the same semantics as a non-volatile <tt>store</tt> to @@ -567,7 +563,7 @@ implement reference counting.</p> i8* @llvm.gcread(i8* %object, i8** %derived)<br> </tt></div> -<div class="doc_text"> +<div> <p>For read barriers, LLVM provides the <tt>llvm.gcread</tt> intrinsic function. It has exactly the same semantics as a non-volatile <tt>load</tt> from the @@ -580,13 +576,17 @@ writes.</p> </div> +</div> + +</div> + <!-- *********************************************************************** --> <h2> <a name="plugin">Implementing a collector plugin</a> </h2> <!-- *********************************************************************** --> -<div class="doc_text"> +<div> <p>User code specifies which GC code generation to use with the <tt>gc</tt> function attribute or, equivalently, with the <tt>setGC</tt> method of @@ -666,14 +666,12 @@ $ llvm-as < sample.ll | llc -load=MyGC.so</pre></blockquote> <p>It is also possible to statically link the collector plugin into tools, such as a language-specific compiler front-end.</p> -</div> - <!-- ======================================================================= --> <h3> <a name="collector-algos">Overview of available features</a> </h3> -<div class="doc_text"> +<div> <p><tt>GCStrategy</tt> provides a range of features through which a plugin may do useful work. Some of these are callbacks, some are algorithms that can @@ -962,7 +960,7 @@ interest.</p> <a name="stack-map">Computing stack maps</a> </h3> -<div class="doc_text"> +<div> <p>LLVM automatically computes a stack map. One of the most important features of a <tt>GCStrategy</tt> is to compile this information into the executable in @@ -1018,7 +1016,7 @@ for collector plugins which implement reference counting or a shadow stack.</p> <a name="init-roots">Initializing roots to null: <tt>InitRoots</tt></a> </h3> -<div class="doc_text"> +<div> <blockquote><pre >MyGC::MyGC() { @@ -1044,7 +1042,7 @@ this feature should be used by all GC plugins. It is enabled by default.</p> <tt>CustomReadBarriers</tt>, and <tt>CustomWriteBarriers</tt></a> </h3> -<div class="doc_text"> +<div> <p>For GCs which use barriers or unusual treatment of stack roots, these flags allow the collector to perform arbitrary transformations of the LLVM @@ -1133,7 +1131,7 @@ bool MyGC::performCustomLowering(Function &F) { <a name="safe-points">Generating safe points: <tt>NeededSafePoints</tt></a> </h3> -<div class="doc_text"> +<div> <p>LLVM can compute four kinds of safe points:</p> @@ -1197,7 +1195,7 @@ safe point (because only the topmost function has been patched).</p> <a name="assembly">Emitting assembly code: <tt>GCMetadataPrinter</tt></a> </h3> -<div class="doc_text"> +<div> <p>LLVM allows a plugin to print arbitrary assembly code before and after the rest of a module's assembly code. At the end of the module, the GC can compile @@ -1341,6 +1339,7 @@ void MyGCPrinter::finishAssembly(std::ostream &OS, AsmPrinter &AP, </div> +</div> <!-- *********************************************************************** --> <h2> @@ -1348,7 +1347,7 @@ void MyGCPrinter::finishAssembly(std::ostream &OS, AsmPrinter &AP, </h2> <!-- *********************************************************************** --> -<div class="doc_text"> +<div> <p><a name="appel89">[Appel89]</a> Runtime Tags Aren't Necessary. Andrew W. Appel. Lisp and Symbolic Computation 19(7):703-705, July 1989.</p> |