[flang-commits] [flang] [mlir] [flang][OpenMP] - Add `MapInfoOp` instances for target private variables when needed (PR #109862)

[Pranav Bhandarkar via flang-commits]

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@@ -0,0 +1,131 @@
+//===- MapsForPrivatizedSymbols.cpp
+//-----------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+/// \file
+/// An OpenMP dialect related pass for FIR/HLFIR which creates MapInfoOp
+/// instances for certain privatized symbols.
+/// For example, if an allocatable variable is used in a private clause attached
+/// to a omp.target op, then the allocatable variable's descriptor will be
+/// needed on the device (e.g. GPU). This descriptor needs to be separately
+/// mapped onto the device. This pass creates the necessary omp.map.info ops for
+/// this.
+//===----------------------------------------------------------------------===//
+// TODO:
+// 1. Before adding omp.map.info, check if in case we already have an
+//    omp.map.info for the variable in question.
+// 2. Generalize this for more than just omp.target ops.
+//===----------------------------------------------------------------------===//
+
+#include "flang/Optimizer/Dialect/FIRType.h"
+#include "flang/Optimizer/HLFIR/HLFIROps.h"
+#include "flang/Optimizer/OpenMP/Passes.h"
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+#include "mlir/Dialect/OpenMP/OpenMPDialect.h"
+#include "mlir/IR/BuiltinAttributes.h"
+#include "mlir/IR/SymbolTable.h"
+#include "mlir/Pass/Pass.h"
+#include "llvm/Frontend/OpenMP/OMPConstants.h"
+#include "llvm/Support/Debug.h"
+#include <type_traits>
+
+#define DEBUG_TYPE "omp-maps-for-privatized-symbols"
+
+namespace flangomp {
+#define GEN_PASS_DEF_MAPSFORPRIVATIZEDSYMBOLSPASS
+#include "flang/Optimizer/OpenMP/Passes.h.inc"
+} // namespace flangomp
+using namespace mlir;
+namespace {
+class MapsForPrivatizedSymbolsPass
+    : public flangomp::impl::MapsForPrivatizedSymbolsPassBase<
+          MapsForPrivatizedSymbolsPass> {
+
+  bool privatizerNeedsMap(omp::PrivateClauseOp &privatizer) {
+    Region &allocRegion = privatizer.getAllocRegion();
+    Value blockArg0 = allocRegion.getArgument(0);
+    if (blockArg0.use_empty())
+      return false;
+    return true;
+  }
+  omp::MapInfoOp createMapInfo(Location loc, Value var, OpBuilder &builder) {
----------------
bhandarkar-pranav wrote:

Honestly, I didn't try because my `createMapInfo` is so specific (Doing  `llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_TO` only and in all likelihood going to deal with descriptors only). Having said that code reuse is good, so let me try what you are suggesting.

https://github.com/llvm/llvm-project/pull/109862