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diff --git a/chromium/buildtools/third_party/libc++/trunk/www/atomic_design.html b/chromium/buildtools/third_party/libc++/trunk/www/atomic_design.html new file mode 100644 index 00000000000..67021b8736e --- /dev/null +++ b/chromium/buildtools/third_party/libc++/trunk/www/atomic_design.html @@ -0,0 +1,92 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" + "http://www.w3.org/TR/html4/strict.dtd"> +<!-- Material used from: HTML 4.01 specs: http://www.w3.org/TR/html401/ --> +<html> +<head> + <META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> + <title><atomic> design</title> + <link type="text/css" rel="stylesheet" href="menu.css"> + <link type="text/css" rel="stylesheet" href="content.css"> +</head> + +<body> +<div id="menu"> + <div> + <a href="http://llvm.org/">LLVM Home</a> + </div> + + <div class="submenu"> + <label>libc++ Info</label> + <a href="/index.html">About</a> + </div> + + <div class="submenu"> + <label>Quick Links</label> + <a href="http://lists.llvm.org/mailman/listinfo/cfe-dev">cfe-dev</a> + <a href="http://lists.llvm.org/mailman/listinfo/cfe-commits">cfe-commits</a> + <a href="http://llvm.org/bugs/">Bug Reports</a> + <a href="http://llvm.org/svn/llvm-project/libcxx/trunk/">Browse SVN</a> + <a href="http://llvm.org/viewvc/llvm-project/libcxx/trunk/">Browse ViewVC</a> + </div> +</div> + +<div id="content"> + <!--*********************************************************************--> + <h1><atomic> design</h1> + <!--*********************************************************************--> + +<p> +There are currently 3 designs under consideration. They differ in where most +of the implementation work is done. The functionality exposed to the customer +should be identical (and conforming) for all three designs. +</p> + +<ol type="A"> +<li> +<a href="atomic_design_a.html">Minimal work for the library</a> +</li> +<li> +<a href="atomic_design_b.html">Something in between</a> +</li> +<li> +<a href="atomic_design_c.html">Minimal work for the front end</a> +</li> +</ol> + +<p> +With any design, the (back end) compiler writer should note: +</p> + +<blockquote> +<p> +The decision to implement lock-free operations on any given type (or not) is an +ABI-binding decision. One can not change from treating a type as not lock free, +to lock free (or vice-versa) without breaking your ABI. +</p> + +<p> +Example: +</p> + +<blockquote><pre> +TU1.cc +----------- +extern atomic<long long> A; +int foo() { return A.compare_exchange_strong(w, x); } + +TU2.cc +----------- +extern atomic<long long> A; +void bar() { return A.compare_exchange_strong(y, z); } +</pre></blockquote> +</blockquote> + +<p> +If only <em>one</em> of these calls to <tt>compare_exchange_strong</tt> is +implemented with mutex-locked code, then that mutex-locked code will not be +executed mutually exclusively of the one implemented in a lock-free manner. +</p> + +</div> +</body> +</html> |