[flang-commits] [openmp] [mlir] [flang] [Flang][OpenMP] Initial mapping of Fortran pointers and allocatables for target devices (PR #71766)

[Kiran Chandramohan via flang-commits]

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@@ -0,0 +1,145 @@
+#include "flang/Optimizer/Builder/FIRBuilder.h"
+#include "flang/Optimizer/Dialect/FIRType.h"
+#include "flang/Optimizer/Dialect/Support/KindMapping.h"
+#include "flang/Optimizer/Transforms/Passes.h"
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
+#include "mlir/Dialect/OpenMP/OpenMPDialect.h"
+#include "mlir/IR/BuiltinDialect.h"
+#include "mlir/IR/BuiltinOps.h"
+#include "mlir/IR/Operation.h"
+#include "mlir/IR/SymbolTable.h"
+#include "mlir/Pass/Pass.h"
+#include "mlir/Support/LLVM.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include <iterator>
+
+namespace fir {
+#define GEN_PASS_DEF_OMPDESCRIPTORMAPINFOGENPASS
+#include "flang/Optimizer/Transforms/Passes.h.inc"
+} // namespace fir
+
+namespace {
+class OMPDescriptorMapInfoGenPass
+    : public fir::impl::OMPDescriptorMapInfoGenPassBase<
+          OMPDescriptorMapInfoGenPass> {
+
+  void genDescriptorMemberMaps(mlir::omp::MapInfoOp op,
+                               fir::FirOpBuilder &builder,
+                               mlir::Operation *target) {
+    mlir::Location loc = builder.getUnknownLoc();
+    mlir::Value descriptor = op.getVarPtr();
+
+    // If we enter this function, but the mapped type itself is not the
+    // descriptor, then it's likely the address of the descriptor so we
+    // must retrieve the descriptor SSA.
+    if (!fir::isTypeWithDescriptor(op.getVarType())) {
+      if (auto addrOp = mlir::dyn_cast_if_present<fir::BoxAddrOp>(
+              op.getVarPtr().getDefiningOp())) {
+        descriptor = addrOp.getVal();
+      }
+    }
+
+    // The fir::BoxOffsetOp only works with !fir.ref<!fir.box<...>> types, as
+    // allowing it to access non-reference box operations can cause some
+    // problematic SSA IR. However, in the case of assumed shape's the type
+    // is not a !fir.ref, in these cases to retrieve the appropriate
+    // !fir.ref<!fir.box<...>> to access the data we need to map we must
+    // perform an alloca and then store to it and retrieve the data from the new
+    // alloca.
+    if (mlir::isa<fir::BaseBoxType>(descriptor.getType())) {
+      mlir::OpBuilder::InsertPoint insPt = builder.saveInsertionPoint();
+      builder.setInsertionPointToStart(builder.getAllocaBlock());
+      auto alloca = builder.create<fir::AllocaOp>(loc, descriptor.getType());
+      builder.restoreInsertionPoint(insPt);
+      builder.create<fir::StoreOp>(loc, descriptor, alloca);
+      descriptor = alloca;
+    }
+
+    mlir::Value baseAddrAddr = builder.create<fir::BoxOffsetOp>(
+        loc, descriptor, fir::BoxFieldAttr::base_addr);
+
+    // Member of the descriptor pointing at the allocated data
+    mlir::Value baseAddr = builder.create<mlir::omp::MapInfoOp>(
+        loc, baseAddrAddr.getType(), baseAddrAddr,
+        llvm::cast<mlir::omp::PointerLikeType>(
+            fir::unwrapRefType(baseAddrAddr.getType()))
+            .getElementType(),
+        mlir::Value{}, mlir::SmallVector<mlir::Value>{}, op.getBounds(),
+        builder.getIntegerAttr(builder.getIntegerType(64, false),
+                               op.getMapType().value()),
+        builder.getAttr<mlir::omp::VariableCaptureKindAttr>(
+            mlir::omp::VariableCaptureKind::ByRef),
+        builder.getStringAttr("") /*name*/);
+
+    // TODO: map the addendum segment of the descriptor, similarly to the
+    // above base address/data pointer member.
+
+    op.getVarPtrMutable().assign(descriptor);
+    op.setVarType(fir::unwrapRefType(descriptor.getType()));
+    op.getMembersMutable().append(baseAddr);
+    op.getBoundsMutable().assign(llvm::SmallVector<mlir::Value>{});
+
+    if (auto mapClauseOwner =
+            llvm::dyn_cast<mlir::omp::MapClauseOwningOpInterface>(target)) {
+      llvm::SmallVector<mlir::Value> newMapOps;
+      mlir::OperandRange mapOperandsArr = mapClauseOwner.getMapOperands();
+
+      for (size_t i = 0; i < mapOperandsArr.size(); ++i) {
+        if (mapOperandsArr[i] == op) {
+          // Push new implicit maps generated for the descriptor.
+          newMapOps.push_back(baseAddr);
+
+          // for TargetOp's which have IsolatedFromAbove we must align the
+          // new additional map operand with an appropriate BlockArgument,
+          // as the printing and later processing currently requires a 1:1
+          // mapping of BlockArgs to MapInfoOp's at the same placement in
+          // each array (BlockArgs and MapOperands).
+          if (auto targetOp = llvm::dyn_cast<mlir::omp::TargetOp>(target))
+            targetOp.getRegion().insertArgument(i, baseAddr.getType(), loc);
+        }
+
+        newMapOps.push_back(mapOperandsArr[i]);
+      }
+
+      mapClauseOwner.getMapOperandsMutable().assign(newMapOps);
+    }
+  }
+
+  // This pass executes on mlir::ModuleOp's finding omp::MapInfoOp's containing
+  // descriptor based types (allocatables, pointers, assumed shape etc.) and
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kiranchandramohan wrote:

Isn't it possible to run at the funcOp level?

https://github.com/llvm/llvm-project/pull/71766