[llvm-branch-commits] [OpenMP][MLIR] Extend explicit derived type member mapping support for OpenMP dialects lowering to LLVM-IR (PR #81510)

[Kareem Ergawy via llvm-branch-commits]

================
@@ -1783,6 +1783,98 @@ void collectMapDataFromMapOperands(MapInfoData &mapData,
   }
 }
 
+static int getMapDataMemberIdx(MapInfoData &mapData,
+                               mlir::omp::MapInfoOp memberOp) {
+  int memberDataIdx = -1;
+  for (size_t i = 0; i < mapData.MapClause.size(); ++i) {
+    if (mapData.MapClause[i] == memberOp)
+      memberDataIdx = i;
+  }
+  return memberDataIdx;
+}
+
+static mlir::omp::MapInfoOp
+getFirstOrLastMappedMemberPtr(mlir::omp::MapInfoOp mapInfo, bool first) {
+  // Only 1 member has been mapped, we can return it.
+  if (mapInfo.getMembersIndex()->size() == 1)
+    if (auto mapOp = mlir::dyn_cast<mlir::omp::MapInfoOp>(
+            mapInfo.getMembers()[0].getDefiningOp()))
+      return mapOp;
+
+  int64_t curPos =
+      mapInfo.getMembersIndex()->begin()->cast<mlir::IntegerAttr>().getInt();
+
+  int64_t idx = 1, curIdx = 0, memberPlacement = 0;
+  for (const auto *iter = std::next(mapInfo.getMembersIndex()->begin());
+       iter != mapInfo.getMembersIndex()->end(); iter++) {
+    memberPlacement = iter->cast<mlir::IntegerAttr>().getInt();
+    if (first) {
+      if (memberPlacement < curPos) {
+        curIdx = idx;
+        curPos = memberPlacement;
+      }
+    } else {
+      if (memberPlacement > curPos) {
+        curIdx = idx;
+        curPos = memberPlacement;
+      }
+    }
+    idx++;
+  }
----------------
ergawy wrote:

Can we instead sort `getMembersIndex()` somehow and fetch either the head or the tail based on `first`? Not sure how easy it is but my feeling is that it should be possible and would be easier to understand.

Or guarantee that it is always sorted on op creation/update. But maybe this is not worth it.

https://github.com/llvm/llvm-project/pull/81510