<tr><td><a href="#adce">-adce</a></td><td>Aggressive Dead Code Elimination</td></tr>
<tr><td><a href="#always-inline">-always-inline</a></td><td>Inliner for always_inline functions</td></tr>
<tr><td><a href="#argpromotion">-argpromotion</a></td><td>Promote 'by reference' arguments to scalars</td></tr>
+<tr><td><a href="#bb-vectorize">-bb-vectorize</a></td><td>Combine instructions to form vector instructions within basic blocks</td></tr>
<tr><td><a href="#block-placement">-block-placement</a></td><td>Profile Guided Basic Block Placement</td></tr>
<tr><td><a href="#break-crit-edges">-break-crit-edges</a></td><td>Break critical edges in CFG</td></tr>
<tr><td><a href="#codegenprepare">-codegenprepare</a></td><td>Optimize for code generation</td></tr>
<tr><td><a href="#loop-unswitch">-loop-unswitch</a></td><td>Unswitch loops</td></tr>
<tr><td><a href="#loweratomic">-loweratomic</a></td><td>Lower atomic intrinsics to non-atomic form</td></tr>
<tr><td><a href="#lowerinvoke">-lowerinvoke</a></td><td>Lower invoke and unwind, for unwindless code generators</td></tr>
-<tr><td><a href="#lowersetjmp">-lowersetjmp</a></td><td>Lower Set Jump</td></tr>
<tr><td><a href="#lowerswitch">-lowerswitch</a></td><td>Lower SwitchInst's to branches</td></tr>
<tr><td><a href="#mem2reg">-mem2reg</a></td><td>Promote Memory to Register</td></tr>
<tr><td><a href="#memcpyopt">-memcpyopt</a></td><td>MemCpy Optimization</td></tr>
<a name="basicaa">-basicaa: Basic Alias Analysis (stateless AA impl)</a>
</h3>
<div>
- <p>
- This is the default implementation of the Alias Analysis interface
- that simply implements a few identities (two different globals cannot alias,
- etc), but otherwise does no analysis.
- </p>
+ <p>A basic alias analysis pass that implements identities (two different
+ globals cannot alias, etc), but does no stateful analysis.</p>
</div>
<!-------------------------------------------------------------------------- -->
</h3>
<div>
<p>
- Always returns "I don't know" for alias queries. NoAA is unlike other alias
- analysis implementations, in that it does not chain to a previous analysis. As
- such it doesn't follow many of the rules that other alias analyses must.
+ This is the default implementation of the Alias Analysis interface. It always
+ returns "I don't know" for alias queries. NoAA is unlike other alias analysis
+ implementations, in that it does not chain to a previous analysis. As such it
+ doesn't follow many of the rules that other alias analyses must.
</p>
</div>
</p>
</div>
+<!-------------------------------------------------------------------------- -->
+<h3>
+ <a name="bb-vectorize">-bb-vectorize: Basic-Block Vectorization</a>
+</h3>
+<div>
+ <p>This pass combines instructions inside basic blocks to form vector
+ instructions. It iterates over each basic block, attempting to pair
+ compatible instructions, repeating this process until no additional
+ pairs are selected for vectorization. When the outputs of some pair
+ of compatible instructions are used as inputs by some other pair of
+ compatible instructions, those pairs are part of a potential
+ vectorization chain. Instruction pairs are only fused into vector
+ instructions when they are part of a chain longer than some
+ threshold length. Moreover, the pass attempts to find the best
+ possible chain for each pair of compatible instructions. These
+ heuristics are intended to prevent vectorization in cases where
+ it would not yield a performance increase of the resulting code.
+ </p>
+</div>
+
<!-------------------------------------------------------------------------- -->
<h3>
<a name="block-placement">-block-placement: Profile Guided Basic Block Placement</a>
</p>
</div>
-<!-------------------------------------------------------------------------- -->
-<h3>
- <a name="lowersetjmp">-lowersetjmp: Lower Set Jump</a>
-</h3>
-<div>
- <p>
- Lowers <tt>setjmp</tt> and <tt>longjmp</tt> to use the LLVM invoke and unwind
- instructions as necessary.
- </p>
-
- <p>
- Lowering of <tt>longjmp</tt> is fairly trivial. We replace the call with a
- call to the LLVM library function <tt>__llvm_sjljeh_throw_longjmp()</tt>.
- This unwinds the stack for us calling all of the destructors for
- objects allocated on the stack.
- </p>
-
- <p>
- At a <tt>setjmp</tt> call, the basic block is split and the <tt>setjmp</tt>
- removed. The calls in a function that have a <tt>setjmp</tt> are converted to
- invoke where the except part checks to see if it's a <tt>longjmp</tt>
- exception and, if so, if it's handled in the function. If it is, then it gets
- the value returned by the <tt>longjmp</tt> and goes to where the basic block
- was split. <tt>invoke</tt> instructions are handled in a similar fashion with
- the original except block being executed if it isn't a <tt>longjmp</tt>
- except that is handled by that function.
- </p>
-</div>
-
<!-------------------------------------------------------------------------- -->
<h3>
<a name="lowerswitch">-lowerswitch: Lower SwitchInst's to branches</a>