Fix for PR1741.

llvm-svn: 43326

2 files changed, 17 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index 018102112c1..d986adec01f 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -339,8 +339,9 @@ BasicAliasAnalysis::alias(const Value *V1, unsigned V1Size,
           
         // Otherwise, nothing is known...
       } else if (O1 != O2) {
-        // If they are two different objects, we know that we have no alias...
-        return NoAlias;
+        if (!isa<Argument>(O1))
+          // If they are two different objects, we know that we have no alias...
+          return NoAlias;
       }
 
       // If they are the same object, they we can look at the indexes.  If they
diff --git a/llvm/test/Analysis/BasicAA/2007-10-24-ArgumentsGlobals.ll b/llvm/test/Analysis/BasicAA/2007-10-24-ArgumentsGlobals.ll
new file mode 100644
index 00000000000..61ab80d5475
--- /dev/null
+++ b/llvm/test/Analysis/BasicAA/2007-10-24-ArgumentsGlobals.ll
@@ -0,0 +1,14 @@
+; RUN: llvm-as < %s | opt -basicaa -gvn -dce | llvm-dis | grep tmp7
+
+        %struct.A = type { i32 }
+        %struct.B = type { %struct.A }
+@a = global %struct.B zeroinitializer           ; <%struct.B*> [#uses=2]
+
+define i32 @_Z3fooP1A(%struct.A* %b) {
+entry:
+        store i32 1, i32* getelementptr (%struct.B* @a, i32 0, i32 0, i32 0), align 8
+        %tmp4 = getelementptr %struct.A* %b, i32 0, i32 0               ;<i32*> [#uses=1]
+        store i32 0, i32* %tmp4, align 4
+        %tmp7 = load i32* getelementptr (%struct.B* @a, i32 0, i32 0, i32 0), align 8           ; <i32> [#uses=1]
+        ret i32 %tmp7
+}