[flang-commits] [flang] [flang][acc] Add ACCDeclareActionConversion pass (PR #181894)

[Razvan Lupusoru via flang-commits]

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+//===- ACCDeclareActionConversion.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
+//
+//===----------------------------------------------------------------------===//
+//
+// Implements the allocation and deallocation semantics for allocatables and
+// pointers in declare directives. OpenACC 3.4, Section 2.13.2: in Fortran, if
+// a variable in the declare var-list has the allocatable or pointer attribute,
+// then for a non-shared memory device, an allocate (or intrinsic assignment
+// that allocates) allocates in both local and device memory and sets the
+// dynamic reference counter to one; a deallocate (or assignment that
+// deallocates) deallocates from both and sets the counter to zero.
+//
+// How this pass works:
+// - Lowering generates recipe functions that hold the recipe for creating the
+//   device copy (using acc dialect operations, e.g. acc.create).
+// - Lowering also attaches an attribute to the operations that allocate or
+//   deallocate the object.
+// - This pass finds operations with that attribute and inserts calls to the
+//   corresponding recipe.
+//
+// Example:
+//   module mm
+//     real, allocatable :: arr(:)
+//     !$acc declare create(arr)
+//   contains
+//     subroutine sub()
+//       allocate(arr(100))
+//     end subroutine sub
+//   end module mm
+//
+// Relevant IR before this pass (recipe function and store with attribute):
+//   func.func private @_QMmmEarr_acc_declare_update_desc_post_alloc(...) {
+//     ...  // acc ops to create/register device copy
+//     return
+//   }
+//   func.func @_QMmmPsub() {
+//     ...
+//     fir.store %box to %desc {acc.declare_action = #acc.declare_action<
+//       postAlloc = @_QMmmEarr_acc_declare_update_desc_post_alloc>} ...
+//   }
+//
+// After this pass (call to recipe inserted after the store):
+//   func.func @_QMmmPsub() {
+//     ...
+//     fir.store %box to %desc ...
+//     call @_QMmmEarr_acc_declare_update_desc_post_alloc()
+//   }
+//
+//===----------------------------------------------------------------------===//
+
+#include "flang/Optimizer/Dialect/FIROps.h"
+#include "flang/Optimizer/Dialect/FIRType.h"
+#include "flang/Optimizer/OpenACC/Passes.h"
+#include "flang/Optimizer/OpenACC/Support/FIROpenACCUtils.h"
+#include "mlir/Dialect/Func/IR/FuncOps.h"
+#include "mlir/Dialect/OpenACC/OpenACC.h"
+#include "mlir/IR/Builders.h"
+#include "mlir/IR/Operation.h"
+#include "mlir/IR/SymbolTable.h"
+#include "mlir/IR/Value.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/TypeSwitch.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "fir-acc-declare-action-conversion"
+
+namespace fir {
+namespace acc {
+#define GEN_PASS_DEF_ACCDECLAREACTIONCONVERSION
+#include "flang/Optimizer/OpenACC/Passes.h.inc"
+} // namespace acc
+} // namespace fir
+
+using namespace mlir;
+
+namespace {
+
+// Fortran runtime symbol names for pointer allocate/deallocate.
+static constexpr llvm::StringRef pointerAllocateName =
+    "_FortranAPointerAllocate";
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razvanlupusoru wrote:

Great suggestion - fixed.

https://github.com/llvm/llvm-project/pull/181894