[Mlir-commits] [flang] [mlir] [flang][acc] Add ACCUseDeviceCanonicalizer pass (PR #175228)

[Razvan Lupusoru]

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+//===- ACCUseDeviceCanonicalizer.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
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass canonicalizes the use_device clause on a host_data construct such
+// that use_device(x) can be lowered to a simple runtime call that takes the
+// actual host pointer as argument.
+//
+// For a use_device operand that is a box type or a reference to a box, the
+// pass:
+//   1. Extracts the host base address for mapping to a device address using
+//      acc.use_device.
+//   2. Creates a new boxed descriptor with the device address as the base
+//      address for use inside the host_data region.
+//
+// The pass also removes unused use_device clauses, reducing the number of
+// runtime calls.
+//
+// Supported use_device operand types:
+//
+//   Scalars:
+//     - !fir.ref<i32>, !fir.ref<f64>, etc.
+//
+//   Arrays:
+//     - Explicit shape (no descriptor): !fir.ref<!fir.array<100xi32>>
+//     - Adjustable size: !fir.ref<!fir.array<?xi32>>
+//     - Assumed shape (handled by hoistBox): !fir.box<!fir.array<?xi32>>
+//     - Assumed size: !fir.ref<!fir.array<?xi32>>
+//     - Deferred shape (handled by hoistRefToBox):
+//         - Allocatable: !fir.ref<!fir.box<!fir.heap<!fir.array<?xi32>>>>
+//         - Pointer: !fir.ref<!fir.box<!fir.ptr<!fir.array<?xi32>>>>
+//     - Subarray specification (handled by hoistBox):
+//     !fir.box<!fir.array<?xi32>>
+//
+//   Not yet supported:
+//     - Assumed rank arrays
+//     - Composite variables: !fir.ref<!fir.type<...>>
+//     - Array elements (device pointer arithmetic in host_data region)
+//     - Composite variable members
+//     - Fortran common blocks: use_device(/cm_block/)
+//
+//===----------------------------------------------------------------------===//
+
+#include "flang/Optimizer/Builder/BoxValue.h"
+#include "flang/Optimizer/Builder/FIRBuilder.h"
+#include "flang/Optimizer/Dialect/FIROps.h"
+#include "flang/Optimizer/Dialect/FIRType.h"
+#include "flang/Optimizer/OpenACC/Passes.h"
+#include "mlir/Dialect/OpenACC/OpenACC.h"
+#include "mlir/IR/PatternMatch.h"
+#include "mlir/IR/Value.h"
+#include "mlir/Pass/Pass.h"
+#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
+#include "llvm/Support/Debug.h"
+#include <cassert>
+
+namespace fir::acc {
+#define GEN_PASS_DEF_ACCUSEDEVICECANONICALIZER
+#include "flang/Optimizer/OpenACC/Passes.h.inc"
+} // namespace fir::acc
+
+#define DEBUG_TYPE "acc-use-device-canonicalizer"
+
+using namespace mlir;
+
+namespace {
+
+static bool isFirRefToBox(Type type) {
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razvanlupusoru wrote:

Agreed. Fixed.

https://github.com/llvm/llvm-project/pull/175228