Seriously strengthen the guarantee offered by noalias on a function's return
value. It must now be as if the pointer were allocated and has not escaped to
the caller. Thanks to Dan Gohman for pointing out the error in the original
and helping devise this definition.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59940 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/LangRef.html b/docs/LangRef.html
index bc3b40b..b469022 100644
--- a/docs/LangRef.html
+++ b/docs/LangRef.html
@@ -892,9 +892,9 @@
<dt><tt>noalias</tt></dt>
<dd>This indicates that the pointer does not alias any global or any other
parameter. The caller is responsible for ensuring that this is the
- case. Additionally, on a function return value <tt>noalias</tt> indicates
- that the pointer does not alias the return value from other calls of
- itself or other noalias functions.</dd>
+ case. On a function return value, <tt>noalias</tt> additionally indicates
+ that the pointer does not alias any other pointers visible to the
+ caller.</dd>
<dt><tt>nest</tt></dt>
<dd>This indicates that the pointer parameter can be excised using the
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index e9c6490..5b65fb1 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -383,9 +383,9 @@
if (isIdentifiedObject(O1) && isIdentifiedObject(O2))
return NoAlias;
- // Local allocations can't alias with arguments or noalias functions.
- if ((isa<AllocationInst>(O1) && (isa<Argument>(O2) || isNoAliasCall(O2))) ||
- (isa<AllocationInst>(O2) && (isa<Argument>(O1) || isNoAliasCall(O1))))
+ // Arguments can't alias with local allocations or noalias calls.
+ if ((isa<Argument>(O1) && (isa<AllocationInst>(O2) || isNoAliasCall(O2))) ||
+ (isa<Argument>(O2) && (isa<AllocationInst>(O1) || isNoAliasCall(O1))))
return NoAlias;
// Most objects can't alias null.