================
@@ -8232,6 +8264,49 @@ convertOmpTarget(Operation &opInst, llvm::IRBuilderBase
&builder,
bool isOffloadEntry =
isTargetDevice || !ompBuilder->Config.TargetTriples.empty();
+ // Validate and resolve in_reduction clauses on omp.target. We currently
+ // only support the non-offload host-fallback path: the per-task private
+ // pointer is obtained by calling __kmpc_task_reduction_get_th_data inside
+ // the to-be-outlined target task body. Threading that pointer through the
+ // device kernel argument list is left as follow-up work.
+ SmallVector<llvm::Value *> inRedOrigPtrs;
+ SmallVector<unsigned> inRedMapArgIdx;
+ if (!targetOp.getInReductionVars().empty()) {
+ if (isTargetDevice || isOffloadEntry)
+ return opInst.emitError(
+ "not yet implemented: in_reduction clause on omp.target with "
+ "offload / target-device compilation");
+ // The byref / cleanup-region / two-argument-initializer in_reduction
+ // shapes are rejected earlier by checkImplementationStatus, and symbol
+ // resolution is guaranteed by verifyReductionVarList.
+ //
+ // The target body has no dedicated in_reduction block argument: each
+ // in_reduction variable is accessed through its map_entries block
argument,
+ // which the host redirects to the per-task reduction-private storage
below.
+ // So each in_reduction variable must also be captured by the target via a
+ // map_entries entry referring to the same outer SSA value. That value is
+ // also used as the `orig` argument of the runtime lookup, so without a
+ // matching map entry the outlined kernel would reference a value defined
in
+ // the host function and fail IR verification. Record, for each
in_reduction
+ // variable, the position of its matching map entry so the corresponding
map
+ // block argument can be redirected once we are inside the body.
+ llvm::SmallDenseMap<Value, unsigned> mapVarPtrToArgIdx;
+ for (auto [idx, mapV] : llvm::enumerate(targetOp.getMapVars()))
+ if (auto mapInfo = mapV.getDefiningOp<omp::MapInfoOp>())
+ mapVarPtrToArgIdx.try_emplace(mapInfo.getVarPtr(), idx);
----------------
Saieiei wrote:
Added a diagnostic for duplicate matching `map_entries` for the same `var_ptr`
when used with `target in_reduction`, plus a negative MLIR test, so we no
longer silently pick an ambiguous redirect target.
https://github.com/llvm/llvm-project/pull/199967
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