Fix a possible null pointer dereference found by the analyzer.
Fix a possible null pointer dereference found by the analyzer.

When computing the other parameters, ‘op’ is checked for being null before it’s dereferenced.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@180271 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang