[Mlir-commits] [mlir] [mlir][OpenMP] Translate reductions on taskloop (PR #199670)

[Tom Eccles]

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@@ -3491,6 +3601,49 @@ convertOmpTaskloopContextOp(omp::TaskloopContextOp contextOp,
       moduleTranslation.mapValue(blockArg, llvmPrivateVar);
     }
 
+    // Map reduction and in_reduction block arguments to the per-task private
+    // storage returned by __kmpc_task_reduction_get_th_data. This call must
+    // be emitted inside the to-be-outlined task body so that it returns the
+    // *executing* thread's gtid (not the encountering thread's). The
+    // taskgroup descriptor `redDesc` is computed in the outer scope and is
+    // auto-captured into the task shareds aggregate by CodeExtractor during
+    // OpenMPIRBuilder::finalize. For in_reduction the descriptor is NULL:
+    // the runtime walks up enclosing taskgroups to find the matching
+    // task_reduction registration for `origPtr`.
+    if (!redDecls.empty() || !inRedDecls.empty()) {
+      auto iface =
+          cast<omp::BlockArgOpenMPOpInterface>(contextOp.getOperation());
+      llvm::OpenMPIRBuilder &ompB = *moduleTranslation.getOpenMPBuilder();
+      llvm::Module *m = moduleTranslation.getLLVMModule();
+      llvm::LLVMContext &llvmCtx = m->getContext();
+      uint32_t srcLocSize;
+      llvm::Constant *srcLocStr = ompB.getOrCreateDefaultSrcLocStr(srcLocSize);
+      llvm::Value *bodyIdent = ompB.getOrCreateIdent(srcLocStr, srcLocSize);
+      llvm::Function *gtidFn = ompB.getOrCreateRuntimeFunctionPtr(
+          llvm::omp::OMPRTL___kmpc_global_thread_num);
+      llvm::Value *bodyGtid =
+          builder.CreateCall(gtidFn, {bodyIdent}, "omp_global_thread_num");
+      llvm::FunctionCallee getThData = ompB.getOrCreateRuntimeFunction(
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tblah wrote:

Could you use OpenMPIRBuilder::getOrCreateThreadID?

https://github.com/llvm/llvm-project/pull/199670