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.

llvm-svn: 59940

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index e9c6490ebb7..5b65fb1199c 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -383,9 +383,9 @@ BasicAliasAnalysis::alias(const Value *V1, unsigned V1Size,
     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.