Extra container data lost when running IDxcOptimizer on bitcode from final DxilContainer

[tex3d]

If one wants to use IDxcOptimizer to run passes on a DxilModule that has been serialized to a container, there are various pieces of data that have been stripped from the module and placed into other container parts which cannot be restored without a more painful manual process.

If IDxcOptimizer could accept a DxilContainer, rather than only module bitcode, it could restore data from the parts to the module, allowing that data to survive the optimization pipeline. When that module is serialized back to a DxilContainer, it will have the data to place into the various parts again.

Lost data that could be restored to the module includes:

• Subobjects from RDAT
• RootSignature from RTS0
• ViewID and I/O dependency data from PSV0
• Resource names and types/annotations from STAT

As it turns out, this is just what's needed by PIX, especially for preserving the subobject data from RDAT.