1 //===- TestPrintDefUse.cpp - Passes to illustrate the IR def-use chains ---===//
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/IR/BuiltinOps.h"
10 #include "mlir/Pass/Pass.h"
11 
12 using namespace mlir;
13 
14 namespace {
15 /// This pass illustrates the IR def-use chains through printing.
16 struct TestPrintDefUsePass
17     : public PassWrapper<TestPrintDefUsePass, OperationPass<>> {
18   StringRef getArgument() const final { return "test-print-defuse"; }
19   StringRef getDescription() const final { return "Test various printing."; }
20   void runOnOperation() override {
21     // Recursively traverse the IR nested under the current operation and print
22     // every single operation and their operands and users.
23     getOperation()->walk([](Operation *op) {
24       llvm::outs() << "Visiting op '" << op->getName() << "' with "
25                    << op->getNumOperands() << " operands:\n";
26 
27       // Print information about the producer of each of the operands.
28       for (Value operand : op->getOperands()) {
29         if (Operation *producer = operand.getDefiningOp()) {
30           llvm::outs() << "  - Operand produced by operation '"
31                        << producer->getName() << "'\n";
32         } else {
33           // If there is no defining op, the Value is necessarily a Block
34           // argument.
35           auto blockArg = operand.cast<BlockArgument>();
36           llvm::outs() << "  - Operand produced by Block argument, number "
37                        << blockArg.getArgNumber() << "\n";
38         }
39       }
40 
41       // Print information about the user of each of the result.
42       llvm::outs() << "Has " << op->getNumResults() << " results:\n";
43       for (const auto &indexedResult : llvm::enumerate(op->getResults())) {
44         Value result = indexedResult.value();
45         llvm::outs() << "  - Result " << indexedResult.index();
46         if (result.use_empty()) {
47           llvm::outs() << " has no uses\n";
48           continue;
49         }
50         if (result.hasOneUse()) {
51           llvm::outs() << " has a single use: ";
52         } else {
53           llvm::outs() << " has "
54                        << std::distance(result.getUses().begin(),
55                                         result.getUses().end())
56                        << " uses:\n";
57         }
58         for (Operation *userOp : result.getUsers()) {
59           llvm::outs() << "    - " << userOp->getName() << "\n";
60         }
61       }
62     });
63   }
64 };
65 } // namespace
66 
67 namespace mlir {
68 void registerTestPrintDefUsePass() { PassRegistration<TestPrintDefUsePass>(); }
69 } // namespace mlir
70