[Flang][OpenMP] Guideline merge for PR #119589 and PR #119588 #669
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This PR introduces a new additional type of map lowering for record types that Clang currently supports, in which a user can map a top-level record type and then individual members with different mapping, effectively creating a sort of "overlapping" mapping that we attempt to cut around. This is currently most predominantly used in Fortran, when mapping descriptors and there data, we map the descriptor and its data with separate map modifiers and "cut around" the pointer data, so that wedo not overwrite it unless the runtime deems it a neccesary action based on its reference counting mechanism. However, it is a mechanism that will come in handy/trigger when a user explitily maps a record type (derived type or structure) and then explicitly maps a member with a different map type. These additions were predominantly in the OpenMPToLLVMIRTranslation.cpp file and phase, however, one Flang test that checks end-to-end IR compilation (as far as we care for now at least) was altered. 2/3 required PRs to enable declare target to mapping, should look at PR 3/3 to check for full green passes (this one will fail a number due to some dependencies). Co-authored-by: Raghu Maddhipatla raghu.maddhipatla@amd.com
…ntation While the infrastructure for declare target to/enter and link for variables exists in the MLIR dialect and at the Flang level, the current lowering from MLIR -> LLVM IR isn't in place, it's only in place for variables that have the link clause applied. This PR aims to extend that lowering to an initial implementation that incorporates declare target to as well, which primarily requires changes in the OpenMPToLLVMIRTranslation phase. However, a minor addition to the OpenMP dialect was required to extend the declare target enumerator to include a default None field as well. This also requires a minor change to the Flang lowering's MapInfoFinlization.cpp pass to alter the map type for descriptors to deal with cases where a variable is marked declare to. Currently, when a descriptor variable is mapped declare target to the descriptor component can become attatched, and cannot be updated, this results in issues when an unusual allocation range is specified (effectively an off-by X error). The current solution is to map the descriptor always, as we always require an up-to-date version of this data. However, this also requires an interlinked PR that adds a more intricate type of mapping of structures/record types that clang currently implements, to circumvent the overwriting of the pointer in the descriptor. 3/3 required PRs to enable declare target to mapping, this PR should pass all tests and provide an all green CI. Co-authored-by: Raghu Maddhipatla raghu.maddhipatla@amd.com
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Nov 24, 2025
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