llvm/mlir/lib/Dialect/Bufferization/Transforms/DropEquivalentBufferResults.cpp

//===- DropEquivalentBufferResults.cpp - Calling convention conversion ----===//
//
// 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 drops return values from functions if they are equivalent to one of
// their arguments. E.g.:
//
// ```
// func.func @foo(%m : memref<?xf32>) -> (memref<?xf32>) {
//   return %m : memref<?xf32>
// }
// ```
//
// This functions is rewritten to:
//
// ```
// func.func @foo(%m : memref<?xf32>) {
//   return
// }
// ```
//
// All call sites are updated accordingly. If a function returns a cast of a
// function argument, it is also considered equivalent. A cast is inserted at
// the call site in that case.

#include "mlir/Dialect/Bufferization/Transforms/Passes.h"

#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
#include "mlir/IR/Operation.h"
#include "mlir/Pass/Pass.h"

namespace mlir {
namespace bufferization {
#define GEN_PASS_DEF_DROPEQUIVALENTBUFFERRESULTS
#include "mlir/Dialect/Bufferization/Transforms/Passes.h.inc"
} // namespace bufferization
} // namespace mlir

usingnamespacemlir;

/// Return the unique ReturnOp that terminates `funcOp`.
/// Return nullptr if there is no such unique ReturnOp.
static func::ReturnOp getAssumedUniqueReturnOp(func::FuncOp funcOp) { … }

/// Return the func::FuncOp called by `callOp`.
static func::FuncOp getCalledFunction(CallOpInterface callOp) { … }

LogicalResult
mlir::bufferization::dropEquivalentBufferResults(ModuleOp module) { … }

namespace {
struct DropEquivalentBufferResultsPass
    : bufferization::impl::DropEquivalentBufferResultsBase<
          DropEquivalentBufferResultsPass> { … };
} // namespace

std::unique_ptr<Pass>
mlir::bufferization::createDropEquivalentBufferResultsPass() { … }