Add new intrinsics:
- llvm.allow.sanitize.address
- llvm.allow.sanitize.thread
- llvm.allow.sanitize.memory
- llvm.allow.sanitize.hwaddress
These intrinsics return true if the corresponding sanitizer is enabled
for the function, and false otherwise. They are lowered by
LowerAllowCheckPass to constant booleans based on the corresponding
sanitize_* function attributes. LowerAllowCheckPass is now "required" to
run on functions with optnone to ensure correct lowering at O0.
The LowerAllowCheckPass already performs similar duties for
@llvm.allow.runtime.check and @llvm.allow.ubsan.check, although with
subtly different semantics (based on profiles and/or sampling). In this
case, we want to make the true/false decision based on if any one of
address/memory/thread sanitization is enabled.
No traps are removed directly nor is this restricted to UBSan, therefore
rename the function doing the transformation of the intrinsic to match
its intent.
NFC.
