[Openmp-commits] [openmp] [Flang][OpenMP][MLIR] Initial array section mapping MLIR -> LLVM-IR lowering utilising omp.bounds (PR #68689)

[via Openmp-commits]

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@@ -1642,13 +1635,154 @@ getRefPtrIfDeclareTarget(mlir::Value value,
   return nullptr;
 }
 
+// A small helper structure to contain data gathered
+// for map lowering and coalese it into one area and
+// avoiding extra computations such as searches in the
+// llvm module for lowered mapped varibles or checking
+// if something is declare target (and retrieving the
+// value) more than neccessary.
+struct MapInfoData : llvm::OpenMPIRBuilder::MapInfosTy {
+  llvm::SmallVector<bool, 4> IsDeclareTarget;
+  llvm::SmallVector<mlir::Operation *, 4> MapClause;
+  llvm::SmallVector<llvm::Value *, 4> OriginalValue;
+  // Stripped off array/pointer to get the underlying
+  // element type
+  llvm::SmallVector<llvm::Type *, 4> BaseType;
+
+  /// Append arrays in \a CurInfo.
+  void append(MapInfoData &CurInfo) {
+    IsDeclareTarget.append(CurInfo.IsDeclareTarget.begin(),
+                           CurInfo.IsDeclareTarget.end());
+    MapClause.append(CurInfo.MapClause.begin(), CurInfo.MapClause.end());
+    OriginalValue.append(CurInfo.OriginalValue.begin(),
+                         CurInfo.OriginalValue.end());
+    BaseType.append(CurInfo.BaseType.begin(), CurInfo.BaseType.end());
+    llvm::OpenMPIRBuilder::MapInfosTy::append(CurInfo);
+  }
+};
+
+uint64_t getArrayElementSizeInBits(LLVM::LLVMArrayType arrTy, DataLayout &dl) {
+  if (auto nestedArrTy = llvm::dyn_cast_if_present<LLVM::LLVMArrayType>(
+          arrTy.getElementType()))
+    return getArrayElementSizeInBits(nestedArrTy, dl);
+  return dl.getTypeSizeInBits(arrTy.getElementType());
+}
+
+// This function calculates the size to be offloaded for a specified type, given
+// its associated map clause (which can contain bounds information which affects
+// the total size), this size is calculated based on the underlying element type
+// e.g. given a 1-D array of ints, we will calculate the size from the integer
+// type * number of elements in the array. This size can be used in other
+// calculations but is ultimately used as an argument to the OpenMP runtimes
+// kernel argument structure which is generated through the combinedInfo data
+// structures.
+// This function is somewhat equivalent to Clang's getExprTypeSize inside of
+// CGOpenMPRuntime.cpp.
+llvm::Value *getSizeInBytes(DataLayout &dl, const mlir::Type &type,
+                            Operation *clauseOp, llvm::IRBuilderBase &builder,
+                            LLVM::ModuleTranslation &moduleTranslation) {
+  // utilising getTypeSizeInBits instead of getTypeSize as getTypeSize gives
+  // the size in inconsistent byte or bit format.
+  uint64_t underlyingTypeSzInBits = dl.getTypeSizeInBits(type);
+  if (auto arrTy = llvm::dyn_cast_if_present<LLVM::LLVMArrayType>(type)) {
+    underlyingTypeSzInBits = getArrayElementSizeInBits(arrTy, dl);
+  }
+
+  if (auto memberClause =
+          mlir::dyn_cast_if_present<mlir::omp::MapInfoOp>(clauseOp)) {
+    // This calculates the size to transfer based on bounds and the underlying
+    // element type, provided bounds have been specified (Fortran
+    // pointers/allocatables/target and arrays that have sections specified fall
+    // into this as well).
+    if (!memberClause.getBounds().empty()) {
+      llvm::Value *elementCount = builder.getInt64(1);
+      for (auto bounds : memberClause.getBounds()) {
+        if (auto boundOp = mlir::dyn_cast_if_present<mlir::omp::DataBoundsOp>(
+                bounds.getDefiningOp())) {
+          // The below calculation for the size to be mapped calculated from the
+          // map_info's bounds is: (elemCount * [UB - LB] + 1), later we
+          // multiply by the underlying element types byte size to get the full
+          // size to be offloaded based on the bounds
+          elementCount = builder.CreateMul(
+              elementCount,
+              builder.CreateAdd(
+                  builder.CreateSub(
+                      moduleTranslation.lookupValue(boundOp.getUpperBound()),
+                      moduleTranslation.lookupValue(boundOp.getLowerBound())),
+                  builder.getInt64(1)));
+        }
+      }
+
+      // The size in bytes x number of elements, the sizeInBytes stored is
+      // the underyling types size, e.g. if ptr<i32>, it'll be the i32's
+      // size, so we do some on the fly runtime math to get the size in
+      // bytes from the extent (ub - lb) * sizeInBytes. NOTE: This may need
+      // some adjustment for members with more complex types.
+      return builder.CreateMul(elementCount,
+                               builder.getInt64(underlyingTypeSzInBits / 8));
+    }
+  }
+
+  return builder.getInt64(underlyingTypeSzInBits / 8);
+}
+
+// Get the underlying LLVM type, this will bypass the pointer and
+// access the underlying type. Which bypasses llvm's opaque pointers
+// to get the underlying type via MLIR.
+llvm::Type *getLLVMIRType(mlir::Type inputType,
+                          LLVM::ModuleTranslation &moduleTranslation) {
+  llvm::Type *type = moduleTranslation.convertType(inputType);
+  if (auto pointerType =
+          llvm::dyn_cast<mlir::omp::PointerLikeType>(inputType)) {
+    if (auto eleType = pointerType.getElementType()) {
----------------
agozillon wrote:

It won't stop working (currently is rebased on all opaque changes), but this is redundant at the moment, and with nested pointers it might lead to an assert, unsure though, but I'll see if I can remove the redundant segment!  

getLLVMIRType is already called with VarType as an argument to inputType at line 1768. 

https://github.com/llvm/llvm-project/pull/68689