Update LLVM and clang from 4.0.1 to 6.0.1 #830

Rust 1.25.0 requires clang 6.0.0. [Release notes for LLVM 6.0.0][1] (excerpt): > ### Non-comprehensive list of changes in this release ### > > * Support for retpolines was added to help mitigate “branch target > injection” (variant #2) of the “Spectre” speculative side channels > described by Project Zero and the Spectre paper. > * The Redirects argument of llvm::sys::ExecuteAndWait and > llvm::sys::ExecuteNoWait was changed to an ArrayRef of optional > StringRef‘s to make it safer and more convenient to use. > * The backend name was added to the Target Registry to allow > run-time information to be fed back into TableGen. Out-of-tree targets > will need to add the name used in the def X : Target definition to the > call to RegisterTarget. > * The Debugify pass was added to opt to facilitate testing of debug > info preservation. This pass attaches synthetic DILocations and > DIVariables to the instructions in a Module. The CheckDebugify pass > determines how much of the metadata is lost. > * Significantly improved quality of CodeView debug info for Windows. > * Preliminary support for Sanitizers and sibling features on > X86(_64) NetBSD (ASan, UBsan, TSan, MSan, SafeStack, libFuzzer). [1]: https://releases.llvm.org/6.0.0/docs/ReleaseNotes.html

[Release notes for 6.0.0][1] (excerpt): > ### Non-comprehensive list of changes in this release ### > > * Support for retpolines was added to help mitigate “branch target injection” > (variant #2) of the “Spectre” speculative side channels described by Project > Zero and the Spectre paper. > * Bitrig OS was merged back into OpenBSD, so Bitrig support has been removed > from Clang/LLVM. > * The default value of _MSC_VER was raised from 1800 to 1911, making it > compatible with the Visual Studio 2015 and 2017 C++ standard library headers. > Users should generally expect this to be regularly raised to match the most > recently released version of the Visual C++ compiler. > * clang now defaults to .init_array if no gcc installation can be found. If a > gcc installation is found, it still prefers .ctors if the found gcc is older > than 4.7.0. > * The new builtin preprocessor macros __is_target_arch, __is_target_vendor, > __is_target_os, and __is_target_environment can be used to to examine the > individual components of the target triple. [1]: https://releases.llvm.org/6.0.0/tools/clang/docs/ReleaseNotes.html

Update LLVM and clang from 4.0.1 to 6.0.1 #830

Update LLVM and clang from 4.0.1 to 6.0.1 #830

Commits on Jun 26, 2018