https://github.com/jtb20 created
https://github.com/llvm/llvm-project/pull/200406
OpenMP 6.0 adds a 'saved' modifier to the data-environment
attribute clauses. On a 'firstprivate' clause it specifies that
the list item's value is captured when the surrounding construct
is recorded into a taskgraph, and that captured value is reused
(rather than re-evaluating the initialiser from the live original)
on every replay. See OpenMP 6.0 [7.5.4], [6.4.7] and [14.3].
This patch implements the front-end plumbing for the modifier:
parsing, AST representation and AST printing, profile, template
instantiation and PCH serialisation, modelled directly on the
existing 'lastprivate(conditional: ...)' machinery. No new
semantic restriction is added here (e.g. requiring a
taskgraph-nested or replayable task context), and codegen and the
runtime continue to treat 'saved' as a no-op for now -- those are
follow-up patches.
Specifically:
- OPENMP_FIRSTPRIVATE_KIND(saved) is added in OpenMPKinds.def,
with a matching OpenMPFirstprivateModifier enum and the
appropriate parse/print helpers in OpenMPKinds.cpp.
- OMPFirstprivateClause gains FPKind / FPKindLoc / ColonLoc
fields and an updated Create() signature; OMPClausePrinter
emits 'firstprivate(saved: ...)' when the modifier is set.
- ParseOpenMP recognises '[modifier:]' inside a firstprivate
clause when OpenMP >= 6.0.
- SemaOpenMP::ActOnOpenMPFirstprivateClause now takes the
modifier triple and diagnoses an unrecognised modifier via
the existing err_omp_unexpected_clause_value path; the
dispatcher in ActOnOpenMPVarListClause and the
implicit-firstprivate emitter in ActOnOpenMPRegionEnd are
updated accordingly.
- TreeTransform forwards the modifier through template
instantiation; ASTReader / ASTWriter round-trip the new
fields.
A new lit test taskgraph_firstprivate_saved_ast_print.cpp covers
ast-print and a PCH emit -> include -> ast-print round-trip on
'omp task' and 'omp taskloop' uses of firstprivate(saved: ...).
Assisted-By: Claude Opus 4.7
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