<li><a href="#ds_bit">BitVector-like containers</a>
<ul>
<li><a href="#dss_bitvector">A dense bitvector</a></li>
+ <li><a href="#dss_smallbitvector">A "small" dense bitvector</a></li>
<li><a href="#dss_sparsebitvector">A sparse bitvector</a></li>
</ul></li>
</ul>
<li><a href="#shutdown">Ending execution with <tt>llvm_shutdown()</tt></a></li>
<li><a href="#managedstatic">Lazy initialization with <tt>ManagedStatic</tt></a></li>
<li><a href="#llvmcontext">Achieving Isolation with <tt>LLVMContext</tt></a></li>
+ <li><a href="#jitthreading">Threads and the JIT</a></li>
</ul>
</li>
which points to temporary (stack allocated) objects. Twines can be implicitly
constructed as the result of the plus operator applied to strings (i.e., a C
strings, an <tt>std::string</tt>, or a <tt>StringRef</tt>). The twine delays the
-actual concatentation of strings until it is actually required, at which point
+actual concatenation of strings until it is actually required, at which point
it can be efficiently rendered directly into a character array. This avoids
unnecessary heap allocation involved in constructing the temporary results of
string concatenation. See
</div>
<div class="doc_text">
-<p><tt>ilist</tt>s have another speciality that must be considered. To be a good
+<p><tt>ilist</tt>s have another specialty that must be considered. To be a good
citizen in the C++ ecosystem, it needs to support the standard container
operations, such as <tt>begin</tt> and <tt>end</tt> iterators, etc. Also, the
<tt>operator--</tt> must work correctly on the <tt>end</tt> iterator in the
</div>
<div class="doc_text">
-<p> The BitVector container provides a fixed size set of bits for manipulation.
+<p> The BitVector container provides a dynamic size set of bits for manipulation.
It supports individual bit setting/testing, as well as set operations. The set
operations take time O(size of bitvector), but operations are performed one word
at a time, instead of one bit at a time. This makes the BitVector very fast for
</p>
</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="dss_smallbitvector">SmallBitVector</a>
+</div>
+
+<div class="doc_text">
+<p> The SmallBitVector container provides the same interface as BitVector, but
+it is optimized for the case where only a small number of bits, less than
+25 or so, are needed. It also transparently supports larger bit counts, but
+slightly less efficiently than a plain BitVector, so SmallBitVector should
+only be used when larger counts are rare.
+</p>
+
+<p>
+At this time, SmallBitVector does not support set operations (and, or, xor),
+and its operator[] does not provide an assignable lvalue.
+</p>
+</div>
+
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
<a name="dss_sparsebitvector">SparseBitVector</a>
LLVM was built without multithreading support, typically because GCC atomic
intrinsics were not found in your system compiler. In this case, the LLVM API
will not be safe for concurrent calls. However, it <em>will</em> be safe for
-hosting threaded applications in the JIT, though care must be taken to ensure
-that side exits and the like do not accidentally result in concurrent LLVM API
-calls.
+hosting threaded applications in the JIT, though <a href="#jitthreading">care
+must be taken</a> to ensure that side exits and the like do not accidentally
+result in concurrent LLVM API calls.
</p>
</div>
</p>
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="jitthreading">Threads and the JIT</a>
+</div>
+
+<div class="doc_text">
+<p>
+LLVM's "eager" JIT compiler is safe to use in threaded programs. Multiple
+threads can call <tt>ExecutionEngine::getPointerToFunction()</tt> or
+<tt>ExecutionEngine::runFunction()</tt> concurrently, and multiple threads can
+run code output by the JIT concurrently. The user must still ensure that only
+one thread accesses IR in a given <tt>LLVMContext</tt> while another thread
+might be modifying it. One way to do that is to always hold the JIT lock while
+accessing IR outside the JIT (the JIT <em>modifies</em> the IR by adding
+<tt>CallbackVH</tt>s). Another way is to only
+call <tt>getPointerToFunction()</tt> from the <tt>LLVMContext</tt>'s thread.
+</p>
+
+<p>When the JIT is configured to compile lazily (using
+<tt>ExecutionEngine::DisableLazyCompilation(false)</tt>), there is currently a
+<a href="http://llvm.org/bugs/show_bug.cgi?id=5184">race condition</a> in
+updating call sites after a function is lazily-jitted. It's still possible to
+use the lazy JIT in a threaded program if you ensure that only one thread at a
+time can call any particular lazy stub and that the JIT lock guards any IR
+access, but we suggest using only the eager JIT in threaded programs.
+</p>
+</div>
+
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="advanced">Advanced Topics</a>
<div class="doc_text">
<ul>
- <li><tt>bool isInteger() const</tt>: Returns true for any integer type.</li>
+ <li><tt>bool isIntegerTy() const</tt>: Returns true for any integer type.</li>
- <li><tt>bool isFloatingPoint()</tt>: Return true if this is one of the two
+ <li><tt>bool isFloatingPointTy()</tt>: Return true if this is one of the five
floating point types.</li>
<li><tt>bool isAbstract()</tt>: Return true if the type is abstract (contains
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