Log Message:
LLVM 4.0.0:
The minimum compiler version required for building LLVM has been raised to 4.8 \ 
for GCC and 2015 for Visual Studio.
The C API functions LLVMAddFunctionAttr, LLVMGetFunctionAttr, \ 
LLVMRemoveFunctionAttr, LLVMAddAttribute, LLVMRemoveAttribute, LLVMGetAttribute, \ 
LLVMAddInstrAttribute and LLVMRemoveInstrAttribute have been removed.
The C API enum LLVMAttribute has been deleted.
The definition and uses of LLVM_ATRIBUTE_UNUSED_RESULT in the LLVM source were \ 
replaced with LLVM_NODISCARD, which matches the C++17 [[nodiscard]] semantics \ 
rather than gcc’s __attribute__((warn_unused_result)).
The Timer related APIs now expect a Name and Description. When upgrading code \ 
the previously used names should become descriptions and a short name in the \ 
style of a programming language identifier should be added.
LLVM now handles invariant.group across different basic blocks, which makes it \ 
possible to devirtualize virtual calls inside loops.
The aggressive dead code elimination phase (“adce”) now removes \ 
branches which do not effect program behavior. Loops are retained by default \ 
since they may be infinite but these can also be removed with LLVM option \ 
-adce-remove-loops when the loop body otherwise has no live operations.
The llvm-cov tool can now export coverage data as json. Its html output mode has \ 
also improved.