llvm-project

89bb99dd - [acc][flang] Implement acc interface for tracking type descriptors (#168982)

[acc][flang] Implement acc interface for tracking type descriptors (#168982) FIR operations that use derived types need to have type descriptor globals available on device when offloading. Examples of this can be seen in `CUFDeviceGlobal` which ensures that such type descriptor uses work on device for CUF. Similarly, this is needed for OpenACC. This change introduces a new interface to the OpenACC dialect named `IndirectGlobalAccessOpInterface` which can be attached to operations that may result in generation of accesses that use type descriptor globals. This functionality is needed for the `ACCImplicitDeclare` pass that is coming in a follow-up change which implicitly ensures that all referenced globals are available in OpenACC compute contexts. The interface provides a `getReferencedSymbols` method that collects all global symbols referenced by an operation. When a symbol table is provided, the implementation for FIR recursively walks type descriptor globals to find all transitively referenced symbols. Note that alternately this could have been implemented in different ways: - Codegen could implicitly generate such type globals as needed by changing the technique that relies on populating them during lowering (eg generate them directly in gpu.module during codegen). - This interface could attach to types instead of operations for a potentially more conservative implementation which maps all type descriptors even if the underlying implementation using it won't necessarily need such mapping. The technique chosen here is consistent with `CUFDeviceGlobal` (which walks operations inside `prepareImplicitDeviceGlobals`) and avoids conservative mapping of all type descriptors.