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This change adds the ACCImplicitRoutine pass which implements the
OpenACC specification for implicit routine directives (OpenACC 3.4 spec,
section 2.15.1).
According to the specification: "If no explicit routine directive
applies to a procedure whose definition appears in the program unit
being compiled, then the implementation applies an implicit routine
directive to that procedure if any of the following conditions holds:
The procedure is called or its address is accessed in a compute region."
The pass automatically generates `acc.routine` operations for functions
called within OpenACC compute constructs or within existing routine
functions that do not already have explicit routine directives. It
recursively applies implicit routine directives while avoiding infinite
recursion when dependencies form cycles.
Key features:
- Walks through all OpenACC compute constructs (parallel, kernels,
serial) to identify function calls
- Creates implicit `acc.routine` operations for functions without
explicit routine declarations
- Recursively processes existing `acc.routine` operations to handle
transitive dependencies
- Avoids infinite recursion through proper tracking of processed
routines
- Respects device-type specific bind clauses to skip routines bound to
different device types
Requirements:
- Function operations must implement `mlir::FunctionOpInterface` to be
identified and associated with routine directives.
- Call operations must implement `mlir::CallOpInterface` to detect
function calls and traverse the call graph.
- Optionally pre-register `acc::OpenACCSupport` if custom behavior is
needed for determining if a symbol use is valid within GPU regions (such
as functions which are already considerations for offloading even
without `acc routine` markings)
Co-authored-by: delaram-talaashrafi<dtalaashrafi@nvidia.com>
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