1//===- ReconcileUnrealizedCasts.cpp - Eliminate noop unrealized casts -----===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "mlir/Conversion/ReconcileUnrealizedCasts/ReconcileUnrealizedCasts.h"
10
11#include "mlir/IR/BuiltinOps.h"
12#include "mlir/Pass/Pass.h"
13#include "mlir/Transforms/DialectConversion.h"
14
15namespace mlir {
16#define GEN_PASS_DEF_RECONCILEUNREALIZEDCASTSPASS
17#include "mlir/Conversion/Passes.h.inc"
18} // namespace mlir
19
20using namespace mlir;
21
22namespace {
23
24/// Pass to simplify and eliminate unrealized conversion casts.
25///
26/// This pass processes unrealized_conversion_cast ops in a worklist-driven
27/// fashion. For each matched cast op, if the chain of input casts eventually
28/// reaches a cast op where the input types match the output types of the
29/// matched op, replace the matched op with the inputs.
30///
31/// Example:
32/// %1 = unrealized_conversion_cast %0 : !A to !B
33/// %2 = unrealized_conversion_cast %1 : !B to !C
34/// %3 = unrealized_conversion_cast %2 : !C to !A
35///
36/// In the above example, %0 can be used instead of %3 and all cast ops are
37/// folded away.
38struct ReconcileUnrealizedCasts
39 : public impl::ReconcileUnrealizedCastsPassBase<ReconcileUnrealizedCasts> {
40 ReconcileUnrealizedCasts() = default;
41
42 void runOnOperation() override {
43 SmallVector<UnrealizedConversionCastOp> ops;
44 getOperation()->walk(
45 [&](UnrealizedConversionCastOp castOp) { ops.push_back(castOp); });
46 reconcileUnrealizedCasts(ops);
47 }
48};
49
50} // namespace
51

source code of mlir/lib/Conversion/ReconcileUnrealizedCasts/ReconcileUnrealizedCasts.cpp