From #137386 (comment).

We need to account for when the modern metadata representation (eg tbaa) has changed from DXC. The upstream representation version is what is generated when with code-gen in clang but we will need to lower it to be the DXIL compliant metadata.

In this case, it would entail removing metadata that is unknown in DXIL. As part of this change, we should move the current whitelist of metadata removal to this pass: #136386.

This issue is ready for refinement when we have decided where the pass should be located (DXILTranslateMetadata or new a new DXIL pass).

With that noted, it raises the following implementation questions:

AC:

• Define a pass that translates modern metadata into a DXIL compliant metadata representation
• Add test cases of the passes removing/transforming respective metadata