[Clang] Introduce -fexperimental-sanitize-metadata=
Introduces the frontend flag -fexperimental-sanitize-metadata=, which
enables SanitizerBinaryMetadata instrumentation.
The first intended user of the binary metadata emitted will be a variant
of GWP-TSan [1]. The plan is to open source a stable and production
quality version of GWP-TSan. The development of which, however, requires
upstream compiler support.
[1] https://llvm.org/devmtg/2020-09/slides/Morehouse-GWP-Tsan.pdf
Until the tool has been open sourced, we mark this kind of
instrumentation as "experimental", and reserve the option to change
binary format, remove features, and similar.
Reviewed By: vitalybuka, MaskRay
Differential Revision: https://reviews.llvm.org/D130888