[llvm-commits] [llvm] r107544 - in /llvm/trunk/docs: AliasAnalysis.html LangRef.html

[Dan Gohman]

Author: djg
Date: Fri Jul  2 18:46:54 2010
New Revision: 107544

URL: http://llvm.org/viewvc/llvm-project?rev=107544&view=rev
Log:
Describe which dependencies are relevant to noalias, and document how
AliasAnalyses have the choice to respect noalias.

Modified:
    llvm/trunk/docs/AliasAnalysis.html
    llvm/trunk/docs/LangRef.html

Modified: llvm/trunk/docs/AliasAnalysis.html
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/AliasAnalysis.html?rev=107544&r1=107543&r2=107544&view=diff
==============================================================================
--- llvm/trunk/docs/AliasAnalysis.html (original)
+++ llvm/trunk/docs/AliasAnalysis.html Fri Jul  2 18:46:54 2010
@@ -201,6 +201,11 @@
 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. AliasAnalysis
+implementations may choose to ignore the "irrelevant" dependencies, provided
+their clients do not need to be aware of these dependencies for correctness.</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>

Modified: llvm/trunk/docs/LangRef.html
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.html?rev=107544&r1=107543&r2=107544&view=diff
==============================================================================
--- llvm/trunk/docs/LangRef.html (original)
+++ llvm/trunk/docs/LangRef.html Fri Jul  2 18:46:54 2010
@@ -1053,7 +1053,12 @@
   <dt><tt><b><a name="noalias">noalias</a></b></tt></dt>
   <dd>This indicates that pointer values
       <a href="#pointeraliasing"><i>based</i></a> on the argument or return
-      value do not alias pointer values which are not <i>based</i> on it.
+      value do not alias pointer values which are not <i>based</i> on it,
+      ignoring certain "irrelevant" dependencies.
+      For a call to the parent function, dependencies between memory
+      references from before or after the call and from those during the call
+      are "irrelevant" to the <tt>noalias</tt> keyword for the arguments and
+      return value used in that call.
       The caller shares the responsibility with the callee for ensuring that
       these requirements are met.
       For further details, please see the discussion of the NoAlias response in