1 //===- TestConstantFold.cpp - Pass to test constant folding ---------------===//
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/Pass/Pass.h"
10 #include "mlir/Transforms/FoldUtils.h"
11
12 using namespace mlir;
13
14 namespace {
15 /// Simple constant folding pass.
16 struct TestConstantFold
17 : public PassWrapper<TestConstantFold, OperationPass<>> {
MLIR_DEFINE_EXPLICIT_INTERNAL_INLINE_TYPE_ID__anone37b23d50111::TestConstantFold18 MLIR_DEFINE_EXPLICIT_INTERNAL_INLINE_TYPE_ID(TestConstantFold)
19
20 StringRef getArgument() const final { return "test-constant-fold"; }
getDescription__anone37b23d50111::TestConstantFold21 StringRef getDescription() const final {
22 return "Test operation constant folding";
23 }
24 // All constants in the operation post folding.
25 SmallVector<Operation *> existingConstants;
26
27 void foldOperation(Operation *op, OperationFolder &helper);
28 void runOnOperation() override;
29 };
30 } // namespace
31
foldOperation(Operation * op,OperationFolder & helper)32 void TestConstantFold::foldOperation(Operation *op, OperationFolder &helper) {
33 auto processGeneratedConstants = [this](Operation *op) {
34 existingConstants.push_back(op);
35 };
36
37 // Attempt to fold the specified operation, including handling unused or
38 // duplicated constants.
39 (void)helper.tryToFold(op, processGeneratedConstants);
40 }
41
runOnOperation()42 void TestConstantFold::runOnOperation() {
43 existingConstants.clear();
44
45 // Collect and fold the operations within the operation.
46 SmallVector<Operation *, 8> ops;
47 getOperation()->walk([&](Operation *op) { ops.push_back(op); });
48
49 // Fold the constants in reverse so that the last generated constants from
50 // folding are at the beginning. This creates somewhat of a linear ordering to
51 // the newly generated constants that matches the operation order and improves
52 // the readability of test cases.
53 OperationFolder helper(&getContext());
54 for (Operation *op : llvm::reverse(ops))
55 foldOperation(op, helper);
56
57 // By the time we are done, we may have simplified a bunch of code, leaving
58 // around dead constants. Check for them now and remove them.
59 for (auto *cst : existingConstants) {
60 if (cst->use_empty())
61 cst->erase();
62 }
63 }
64
65 namespace mlir {
66 namespace test {
registerTestConstantFold()67 void registerTestConstantFold() { PassRegistration<TestConstantFold>(); }
68 } // namespace test
69 } // namespace mlir
70