Introduce -DLLVM_USE_SANITIZER=Undefined CMake option to build UBSan-ified version of LLVM/Clang.

I've fixed most of the simple bugs and currently "check-llvm" test suite
has 26 failures, and "check-clang" suite has 5 failures.

llvm-svn: 216701

cmake/modules/HandleLLVMOptions.cmake

@@ -363,6 +363,10 @@ if(LLVM_USE_SANITIZER)
       if(LLVM_USE_SANITIZER STREQUAL "MemoryWithOrigins")
         append("-fsanitize-memory-track-origins" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
       endif()
+    elseif (LLVM_USE_SANITIZER STREQUAL "Undefined")
+      append_common_sanitizer_flags()
+      append("-fsanitize=undefined -fno-sanitize=vptr -fno-sanitize-recover"
+              CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
     else()
       message(WARNING "Unsupported value of LLVM_USE_SANITIZER: ${LLVM_USE_SANITIZER}")
     endif()

docs/CMake.rst

@@ -288,8 +288,8 @@ LLVM-specific variables
 
 **LLVM_USE_SANITIZER**:STRING
   Define the sanitizer used to build LLVM binaries and tests. Possible values
-  are ``Address``, ``Memory`` and ``MemoryWithOrigins``. Defaults to empty
-  string.
+  are ``Address``, ``Memory``, ``MemoryWithOrigins`` and ``Undefined``.
+  Defaults to empty string.
 
 **LLVM_BUILD_DOCS**:BOOL
   Enables all enabled documentation targets (i.e. Doxgyen and Sphinx targets) to

test/lit.cfg

@@ -96,7 +96,7 @@ for symbolizer in ['ASAN_SYMBOLIZER_PATH', 'MSAN_SYMBOLIZER_PATH']:
         config.environment[symbolizer] = os.environ[symbolizer]
 
 # Propagate options for sanitizers.
-for options in ['ASAN_OPTIONS']:
+for options in ['ASAN_OPTIONS', 'UBSAN_OPTIONS']:
     if options in os.environ:
         config.environment[options] = os.environ[options]