Merging r324308:

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r324308 | rtrieu | 2018-02-06 03:58:21 +0100 (Tue, 06 Feb 2018) | 4 lines

Fix crash on invalid.

Don't call a method when the pointer is null.

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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_60@325766 91177308-0d34-0410-b5e6-96231b3b80d8