reuse result of operator*, it is expensive to recompute

[oota-llvm.git] / docs / AliasAnalysis.html

diff --git a/docs/AliasAnalysis.html b/docs/AliasAnalysis.html
index 5e931d77a8930fb8f8be5147af3e26c763b10637..c6330a946956edd771204f0dade2b71a268889c9 100644 (file)
--- a/docs/AliasAnalysis.html
+++ b/docs/AliasAnalysis.html
@@ -117,6 +117,11 @@ as the actual <tt>call</tt> or <tt>invoke</tt> instructions that performs the
 call.  The <tt>AliasAnalysis</tt> interface also exposes some helper methods
 which allow you to get mod/ref information for arbitrary instructions.</p>
 
+<p>All <tt>AliasAnalysis</tt> interfaces require that in queries involving
+multiple values, values which are not
+<a href="LangRef.html#constants">constants</a> are all defined within the
+same function.</p>
+
 </div>
 
 <!-- ======================================================================= -->
@@ -181,9 +186,13 @@ that the accesses alias.</p>
 </div>
   
 <div class="doc_text">
-The <tt>alias</tt> method is the primary interface used to determine whether or
-not two memory objects alias each other.  It takes two memory objects as input
-and returns MustAlias, MayAlias, or NoAlias as appropriate.
+<p>The <tt>alias</tt> method is the primary interface used to determine whether
+or not two memory objects alias each other.  It takes two memory objects as
+input and returns MustAlias, MayAlias, or NoAlias as appropriate.</p>
+
+<p>Like all <tt>AliasAnalysis</tt> interfaces, the <tt>alias</tt> method requires
+that either the two pointer values be defined within the same function, or at
+least one of the values is a <a href="LangRef.html#constants">constant</a>.</p>
 </div>
 
 <!-- _______________________________________________________________________ -->
@@ -201,6 +210,10 @@ freed and reallocated between accesses through one pointer and accesses through
 the other -- in this case, there is a dependence, but it's mediated by the free
 and reallocation.</p>
 
+<p>As an exception to this is with the
+<a href="LangRef.html#noalias"><tt>noalias</tt></a> keyword; the "irrelevant"
+dependencies are ignored.</p>
+
 <p>The MayAlias response is used whenever the two pointers might refer to the
 same object.  If the two memory objects overlap, but do not start at the same
 location, return MayAlias.</p>