Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/include/llvm/CodeGen/UnreachableBlockElim.h b/linux-x64/clang/include/llvm/CodeGen/UnreachableBlockElim.h
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+++ b/linux-x64/clang/include/llvm/CodeGen/UnreachableBlockElim.h
@@ -0,0 +1,37 @@
+//===-- UnreachableBlockElim.h - Remove unreachable blocks for codegen --===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass is an extremely simple version of the SimplifyCFG pass. Its sole
+// job is to delete LLVM basic blocks that are not reachable from the entry
+// node. To do this, it performs a simple depth first traversal of the CFG,
+// then deletes any unvisited nodes.
+//
+// Note that this pass is really a hack. In particular, the instruction
+// selectors for various targets should just not generate code for unreachable
+// blocks. Until LLVM has a more systematic way of defining instruction
+// selectors, however, we cannot really expect them to handle additional
+// complexity.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_CODEGEN_UNREACHABLEBLOCKELIM_H
+#define LLVM_LIB_CODEGEN_UNREACHABLEBLOCKELIM_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class UnreachableBlockElimPass
+ : public PassInfoMixin<UnreachableBlockElimPass> {
+public:
+ PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+} // end namespace llvm
+
+#endif // LLVM_LIB_CODEGEN_UNREACHABLEBLOCKELIM_H