[Flang][OpenMP][MLIR] Initial derived type member map support

This patch is one in a series of four patches that seeks to refactor
slightly and extend the current record type map support that was
put in place for Fortran's descriptor types to handle explicit
member mapping for record types at a single level of depth.

For example, the below case where two members of a Fortran
derived type are mapped explicitly:

''''
  type :: scalar_and_array
    real(4) :: real
    integer(4) :: array(10)
    integer(4) :: int
  end type scalar_and_array
  type(scalar_and_array) :: scalar_arr

  !$omp target map(tofrom: scalar_arr%int, scalar_arr%real)
''''

Current cases of derived type mapping left for future work are:
  > explicit member mapping of nested members (e.g. two layers of
     record types where we explicitly map a member from the internal
     record type)
  > Fortran's automagical mapping of all elements and nested elements
     of a derived type
  > explicit member mapping of a derived type and then constituient members
     (redundant in Fortran due to former case but still legal as far as I am aware)
  > explicit member mapping of a record type (may be handled reasonably, just
     not fully tested in this iteration)
  > explicit member mapping for Fortran allocatable types (a variation of nested
     record types)

This patch seeks to support this by extending the Flang-new OpenMP lowering to
support generation of this newly required information, creating the neccessary
parent <-to-> member map_info links, calculating the member indices and
setting if it's a partial map.

The OMPDescriptorMapInfoGen pass has also been generalized into a map
finalization phase, now named OMPMapInfoFinalization. This pass was extended
to support the insertion of member maps into the BlockArg and MapOperands of
relevant map carrying operations. Similar to the method in which descriptor types
are expanded and constituient members inserted.

Pull Request: #82853

Author: agozillon

flang/docs/OpenMP-descriptor-management.md

@@ -44,7 +44,7 @@ Currently, Flang will lower these descriptor types in the OpenMP lowering (lower
 to all other map types, generating an omp.MapInfoOp containing relevant information required for lowering
 the OpenMP dialect to LLVM-IR during the final stages of the MLIR lowering. However, after 
 the lowering to FIR/HLFIR has been performed an OpenMP dialect specific pass for Fortran, 
-`OMPDescriptorMapInfoGenPass` (Optimizer/OMPDescriptorMapInfoGen.cpp) will expand the 
+`OMPMapInfoFinalizationPass` (Optimizer/OMPMapInfoFinalization.cpp) will expand the 
 `omp.MapInfoOp`'s containing descriptors (which currently will be a `BoxType` or `BoxAddrOp`) into multiple 
 mappings, with one extra per pointer member in the descriptor that is supported on top of the original
 descriptor map operation. These pointers members are linked to the parent descriptor by adding them to 
@@ -53,7 +53,7 @@ owning operation's (`omp.TargetOp`, `omp.TargetDataOp` etc.) map operand list an
 operation is `IsolatedFromAbove`, it also inserts them as `BlockArgs` to canonicalize the mappings and
 simplify lowering.
 
-An example transformation by the `OMPDescriptorMapInfoGenPass`:
+An example transformation by the `OMPMapInfoFinalizationPass`:
 
 ```
 

flang/include/flang/Optimizer/Transforms/Passes.h

@@ -68,7 +68,7 @@ std::unique_ptr<mlir::Pass> createAlgebraicSimplificationPass();
 std::unique_ptr<mlir::Pass>
 createAlgebraicSimplificationPass(const mlir::GreedyRewriteConfig &config);
 
-std::unique_ptr<mlir::Pass> createOMPDescriptorMapInfoGenPass();
+std::unique_ptr<mlir::Pass> createOMPMapInfoFinalizationPass();
 std::unique_ptr<mlir::Pass> createOMPFunctionFilteringPass();
 std::unique_ptr<mlir::OperationPass<mlir::ModuleOp>>
 createOMPMarkDeclareTargetPass();

flang/include/flang/Optimizer/Transforms/Passes.td

@@ -321,15 +321,15 @@ def LoopVersioning : Pass<"loop-versioning", "mlir::func::FuncOp"> {
   let dependentDialects = [ "fir::FIROpsDialect" ];
 }
 
-def OMPDescriptorMapInfoGenPass
-    : Pass<"omp-descriptor-map-info-gen", "mlir::func::FuncOp"> {
+def OMPMapInfoFinalizationPass
+    : Pass<"omp-map-info-finalization", "mlir::func::FuncOp"> {
   let summary = "expands OpenMP MapInfo operations containing descriptors";
   let description = [{
     Expands MapInfo operations containing descriptor types into multiple 
     MapInfo's for each pointer element in the descriptor that requires 
     explicit individual mapping by the OpenMP runtime.
   }];
-  let constructor = "::fir::createOMPDescriptorMapInfoGenPass()";
+  let constructor = "::fir::createOMPMapInfoFinalizationPass()";
   let dependentDialects = ["mlir::omp::OpenMPDialect"];
 }
 

flang/include/flang/Tools/CLOptions.inc

@@ -335,7 +335,7 @@ inline void createHLFIRToFIRPassPipeline(
 /// rather than the host device.
 inline void createOpenMPFIRPassPipeline(
     mlir::PassManager &pm, bool isTargetDevice) {
-  pm.addPass(fir::createOMPDescriptorMapInfoGenPass());
+  pm.addPass(fir::createOMPMapInfoFinalizationPass());
   pm.addPass(fir::createOMPMarkDeclareTargetPass());
   if (isTargetDevice)
     pm.addPass(fir::createOMPFunctionFilteringPass());

flang/lib/Lower/OpenMP/ClauseProcessor.cpp

@@ -814,38 +814,24 @@ bool ClauseProcessor::processLink(
       });
 }
 
-mlir::omp::MapInfoOp
-createMapInfoOp(fir::FirOpBuilder &builder, mlir::Location loc,
-                mlir::Value baseAddr, mlir::Value varPtrPtr, std::string name,
-                llvm::ArrayRef<mlir::Value> bounds,
-                llvm::ArrayRef<mlir::Value> members, uint64_t mapType,
-                mlir::omp::VariableCaptureKind mapCaptureType, mlir::Type retTy,
-                bool isVal) {
-  if (auto boxTy = mlir::dyn_cast<fir::BaseBoxType>(baseAddr.getType())) {
-    baseAddr = builder.create<fir::BoxAddrOp>(loc, baseAddr);
-    retTy = baseAddr.getType();
-  }
-
-  mlir::TypeAttr varType = mlir::TypeAttr::get(
-      llvm::cast<mlir::omp::PointerLikeType>(retTy).getElementType());
-
-  mlir::omp::MapInfoOp op = builder.create<mlir::omp::MapInfoOp>(
-      loc, retTy, baseAddr, varType, varPtrPtr, members, bounds,
-      builder.getIntegerAttr(builder.getIntegerType(64, false), mapType),
-      builder.getAttr<mlir::omp::VariableCaptureKindAttr>(mapCaptureType),
-      builder.getStringAttr(name));
-
-  return op;
-}
-
 bool ClauseProcessor::processMap(
     mlir::Location currentLocation, Fortran::lower::StatementContext &stmtCtx,
     mlir::omp::MapClauseOps &result,
     llvm::SmallVectorImpl<const Fortran::semantics::Symbol *> *mapSyms,
     llvm::SmallVectorImpl<mlir::Location> *mapSymLocs,
     llvm::SmallVectorImpl<mlir::Type> *mapSymTypes) const {
   fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
-  return findRepeatableClause<omp::clause::Map>(
+  // We always require tracking of symbols, even if the caller does not,
+  // so we create an optionally used local set of symbols when the mapSyms
+  // argument is not present.
+  llvm::SmallVector<const Fortran::semantics::Symbol *> localMapSyms;
+  llvm::SmallVectorImpl<const Fortran::semantics::Symbol *> *ptrMapSyms =
+      mapSyms ? mapSyms : &localMapSyms;
+  std::map<const Fortran::semantics::Symbol *,
+           llvm::SmallVector<OmpMapMemberIndicesData>>
+      parentMemberIndices;
+
+  bool clauseFound = findRepeatableClause<omp::clause::Map>(
       [&](const omp::clause::Map &clause,
           const Fortran::parser::CharBlock &source) {
         using Map = omp::clause::Map;
@@ -910,24 +896,33 @@ bool ClauseProcessor::processMap(
           // Explicit map captures are captured ByRef by default,
           // optimisation passes may alter this to ByCopy or other capture
           // types to optimise
-          mlir::Value mapOp = createMapInfoOp(
-              firOpBuilder, clauseLocation, symAddr, mlir::Value{},
-              asFortran.str(), bounds, {},
+          mlir::omp::MapInfoOp mapOp = createMapInfoOp(
+              firOpBuilder, clauseLocation, symAddr,
+              /*varPtrPtr=*/mlir::Value{}, asFortran.str(), bounds,
+              /*members=*/{}, /*membersIndex=*/mlir::DenseIntElementsAttr{},
               static_cast<
                   std::underlying_type_t<llvm::omp::OpenMPOffloadMappingFlags>>(
                   mapTypeBits),
               mlir::omp::VariableCaptureKind::ByRef, symAddr.getType());
 
-          result.mapVars.push_back(mapOp);
-
-          if (mapSyms)
-            mapSyms->push_back(object.id());
-          if (mapSymLocs)
-            mapSymLocs->push_back(symAddr.getLoc());
-          if (mapSymTypes)
-            mapSymTypes->push_back(symAddr.getType());
+          if (object.id()->owner().IsDerivedType()) {
+            addChildIndexAndMapToParent(object, parentMemberIndices, mapOp,
+                                        semaCtx);
+          } else {
+            result.mapVars.push_back(mapOp);
+            ptrMapSyms->push_back(object.id());
+            if (mapSymTypes)
+              mapSymTypes->push_back(symAddr.getType());
+            if (mapSymLocs)
+              mapSymLocs->push_back(symAddr.getLoc());
+          }
         }
       });
+
+  insertChildMapInfoIntoParent(converter, parentMemberIndices, result.mapVars,
+                               *ptrMapSyms, mapSymTypes, mapSymLocs);
+
+  return clauseFound;
 }
 
 bool ClauseProcessor::processReduction(

flang/lib/Lower/OpenMP/ClauseProcessor.h

@@ -185,7 +185,12 @@ template <typename T>
 bool ClauseProcessor::processMotionClauses(
     Fortran::lower::StatementContext &stmtCtx,
     mlir::omp::MapClauseOps &result) {
-  return findRepeatableClause<T>(
+  std::map<const Fortran::semantics::Symbol *,
+           llvm::SmallVector<OmpMapMemberIndicesData>>
+      parentMemberIndices;
+  llvm::SmallVector<const Fortran::semantics::Symbol *> mapSymbols;
+
+  bool clauseFound = findRepeatableClause<T>(
       [&](const T &clause, const Fortran::parser::CharBlock &source) {
         mlir::Location clauseLocation = converter.genLocation(source);
         fir::FirOpBuilder &firOpBuilder = converter.getFirOpBuilder();
@@ -203,6 +208,7 @@ bool ClauseProcessor::processMotionClauses(
         for (const omp::Object &object : objects) {
           llvm::SmallVector<mlir::Value> bounds;
           std::stringstream asFortran;
+
           Fortran::lower::AddrAndBoundsInfo info =
               Fortran::lower::gatherDataOperandAddrAndBounds<
                   mlir::omp::MapBoundsOp, mlir::omp::MapBoundsType>(
@@ -218,17 +224,29 @@ bool ClauseProcessor::processMotionClauses(
           // Explicit map captures are captured ByRef by default,
           // optimisation passes may alter this to ByCopy or other capture
           // types to optimise
-          mlir::Value mapOp = createMapInfoOp(
-              firOpBuilder, clauseLocation, symAddr, mlir::Value{},
-              asFortran.str(), bounds, {},
+          mlir::omp::MapInfoOp mapOp = createMapInfoOp(
+              firOpBuilder, clauseLocation, symAddr,
+              /*varPtrPtr=*/mlir::Value{}, asFortran.str(), bounds,
+              /*members=*/{}, /*membersIndex=*/mlir::DenseIntElementsAttr{},
               static_cast<
                   std::underlying_type_t<llvm::omp::OpenMPOffloadMappingFlags>>(
                   mapTypeBits),
               mlir::omp::VariableCaptureKind::ByRef, symAddr.getType());
 
-          result.mapVars.push_back(mapOp);
+          if (object.id()->owner().IsDerivedType()) {
+            addChildIndexAndMapToParent(object, parentMemberIndices, mapOp,
+                                        semaCtx);
+          } else {
+            result.mapVars.push_back(mapOp);
+            mapSymbols.push_back(object.id());
+          }
         }
       });
+
+  insertChildMapInfoIntoParent(converter, parentMemberIndices, result.mapVars,
+                               mapSymbols,
+                               /*mapSymTypes=*/nullptr, /*mapSymLocs=*/nullptr);
+  return clauseFound;
 }
 
 template <typename... Ts>

flang/lib/Lower/OpenMP/OpenMP.cpp

@@ -939,8 +939,10 @@ genBodyOfTargetOp(Fortran::lower::AbstractConverter &converter,
         std::stringstream name;
         firOpBuilder.setInsertionPoint(targetOp);
         mlir::Value mapOp = createMapInfoOp(
-            firOpBuilder, copyVal.getLoc(), copyVal, mlir::Value{}, name.str(),
-            bounds, llvm::SmallVector<mlir::Value>{},
+            firOpBuilder, copyVal.getLoc(), copyVal,
+            /*varPtrPtr=*/mlir::Value{}, name.str(), bounds,
+            /*members=*/llvm::SmallVector<mlir::Value>{},
+            /*membersIndex=*/mlir::DenseIntElementsAttr{},
             static_cast<
                 std::underlying_type_t<llvm::omp::OpenMPOffloadMappingFlags>>(
                 llvm::omp::OpenMPOffloadMappingFlags::OMP_MAP_IMPLICIT),
@@ -1637,8 +1639,9 @@ genTargetOp(Fortran::lower::AbstractConverter &converter,
         }
 
         mlir::Value mapOp = createMapInfoOp(
-            firOpBuilder, baseOp.getLoc(), baseOp, mlir::Value{}, name.str(),
-            bounds, {},
+            firOpBuilder, baseOp.getLoc(), baseOp, /*varPtrPtr=*/mlir::Value{},
+            name.str(), bounds, /*members=*/{},
+            /*membersIndex=*/mlir::DenseIntElementsAttr{},
             static_cast<
                 std::underlying_type_t<llvm::omp::OpenMPOffloadMappingFlags>>(
                 mapFlag),