[Sanitizer] Remove brittle cache variable and slightly simplify blacklisting code.
Now CodeGenFunction is responsible for looking at sanitizer blacklist
(in CodeGenFunction::StartFunction) and turning off instrumentation,
if necessary.

No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@212501 91177308-0d34-0410-b5e6-96231b3b80d8
Rename static function to better describe its purpose

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@212502 91177308-0d34-0410-b5e6-96231b3b80d8
[ASan] Completely remove sanitizer blacklist file from instrumentation pass.

All blacklisting logic is now moved to the frontend (Clang).
If a function (or source file it is in) is blacklisted, it doesn't
get sanitize_address attribute and is therefore not instrumented.
If a global variable (or source file it is in) is blacklisted, it is
reported to be blacklisted by the entry in llvm.asan.globals metadata,
and is not modified by the instrumentation.

The latter may lead to certain false positives - not all the globals
created by Clang are described in llvm.asan.globals metadata (e.g,
RTTI descriptors are not), so we may start reporting errors on them
even if "module" they appear in is blacklisted. We assume it's fine
to take such risk:
  1) errors on these globals are rare and usually indicate wild memory access
  2) we can lazily add descriptors for these globals into llvm.asan.globals
     lazily.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@212505 91177308-0d34-0410-b5e6-96231b3b80d8