1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
|
//===- ReconcileUnrealizedCasts.cpp - Eliminate noop unrealized casts -----===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "mlir/Conversion/ReconcileUnrealizedCasts/ReconcileUnrealizedCasts.h"
#include "../PassDetail.h"
#include "mlir/IR/BuiltinOps.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Transforms/DialectConversion.h"
using namespace mlir;
namespace {
/// Removes `unrealized_conversion_cast`s whose results are only used by other
/// `unrealized_conversion_cast`s converting back to the original type. This
/// pattern is complementary to the folder and can be used to process operations
/// starting from the first, i.e. the usual traversal order in dialect
/// conversion. The folder, on the other hand, can only apply to the last
/// operation in a chain of conversions because it is not expected to walk
/// use-def chains. One would need to declare cast ops as dynamically illegal
/// with a complex condition in order to eliminate them using the folder alone
/// in the dialect conversion infra.
struct UnrealizedConversionCastPassthrough
: public OpRewritePattern<UnrealizedConversionCastOp> {
using OpRewritePattern<UnrealizedConversionCastOp>::OpRewritePattern;
LogicalResult matchAndRewrite(UnrealizedConversionCastOp op,
PatternRewriter &rewriter) const override {
// Match the casts that are _only_ used by other casts, with the overall
// cast being a trivial noop: A->B->A.
auto users = op->getUsers();
if (!llvm::all_of(users, [&](Operation *user) {
if (auto other = dyn_cast<UnrealizedConversionCastOp>(user))
return other.getResultTypes() == op.getInputs().getTypes() &&
other.getInputs() == op.getOutputs();
return false;
})) {
return rewriter.notifyMatchFailure(op, "live unrealized conversion cast");
}
for (Operation *user : users)
rewriter.replaceOp(user, op.getInputs());
rewriter.eraseOp(op);
return success();
}
};
/// Pass to simplify and eliminate unrealized conversion casts.
struct ReconcileUnrealizedCasts
: public ReconcileUnrealizedCastsBase<ReconcileUnrealizedCasts> {
ReconcileUnrealizedCasts() = default;
void runOnOperation() override {
RewritePatternSet patterns(&getContext());
populateReconcileUnrealizedCastsPatterns(patterns);
ConversionTarget target(getContext());
target.addIllegalOp<UnrealizedConversionCastOp>();
if (failed(applyPartialConversion(getOperation(), target,
std::move(patterns))))
signalPassFailure();
}
};
} // namespace
void mlir::populateReconcileUnrealizedCastsPatterns(
RewritePatternSet &patterns) {
patterns.add<UnrealizedConversionCastPassthrough>(patterns.getContext());
}
std::unique_ptr<Pass> mlir::createReconcileUnrealizedCastsPass() {
return std::make_unique<ReconcileUnrealizedCasts>();
}
|
