Add support for -fsanitize-blacklist and default blacklists for DFSan.
Also add some documentation.

Differential Revision: http://llvm-reviews.chandlerc.com/D1346

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188403 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/BackendUtil.cpp b/lib/CodeGen/BackendUtil.cpp
index 1edd065..9943287 100644
--- a/lib/CodeGen/BackendUtil.cpp
+++ b/lib/CodeGen/BackendUtil.cpp
@@ -208,7 +208,10 @@
 
 static void addDataFlowSanitizerPass(const PassManagerBuilder &Builder,
                                      PassManagerBase &PM) {
-  PM.add(createDataFlowSanitizerPass());
+  const PassManagerBuilderWrapper &BuilderWrapper =
+      static_cast<const PassManagerBuilderWrapper&>(Builder);
+  const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
+  PM.add(createDataFlowSanitizerPass(CGOpts.SanitizerBlacklistFile));
 }
 
 void EmitAssemblyHelper::CreatePasses(TargetMachine *TM) {