Add nonnull in CodeGen for __attribute__((returns_nonnull))

As a follow-up to r212835, also add the LLVM nonnull function attribute when
__attribute__((returns_nonnull)) is provided.

llvm-svn: 212874

clang/lib/CodeGen/CGCall.cpp

@@ -1107,6 +1107,8 @@ void CodeGenModule::ConstructAttributeList(const CGFunctionInfo &FI,
     }
     if (TargetDecl->hasAttr<MallocAttr>())
       RetAttrs.addAttribute(llvm::Attribute::NoAlias);
+    if (TargetDecl->hasAttr<ReturnsNonNullAttr>())
+      RetAttrs.addAttribute(llvm::Attribute::NonNull);
   }
 
   if (CodeGenOpts.OptimizeSize)

clang/test/CodeGen/nonnull.c

@@ -15,3 +15,9 @@ void bar2(int * x, int * y) __attribute__((nonnull(2)))  {
   *x = 0;
 }
 
+static int a;
+// CHECK: define nonnull i32* @bar3()
+int * bar3() __attribute__((returns_nonnull))  {
+  return &a;
+}
+