1 //===- TestAffineLoopUnswitching.cpp - Test affine if/else hoisting -------===//
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 // This file implements a pass to hoist affine if/else structures.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "mlir/Dialect/Affine/Analysis/Utils.h"
14 #include "mlir/Dialect/Affine/IR/AffineOps.h"
15 #include "mlir/Dialect/Affine/Utils.h"
16 #include "mlir/Pass/Pass.h"
17 #include "mlir/Transforms/Passes.h"
18 
19 #define PASS_NAME "test-affine-loop-unswitch"
20 
21 using namespace mlir;
22 
23 namespace {
24 
25 /// This pass applies the permutation on the first maximal perfect nest.
26 struct TestAffineLoopUnswitching
27     : public PassWrapper<TestAffineLoopUnswitching, FunctionPass> {
28   StringRef getArgument() const final { return PASS_NAME; }
29   StringRef getDescription() const final {
30     return "Tests affine loop unswitching / if/else hoisting";
31   }
32   TestAffineLoopUnswitching() = default;
33   TestAffineLoopUnswitching(const TestAffineLoopUnswitching &pass) = default;
34 
35   void runOnFunction() override;
36 
37   /// The maximum number of iterations to run this for.
38   constexpr static unsigned kMaxIterations = 5;
39 };
40 
41 } // namespace
42 
43 void TestAffineLoopUnswitching::runOnFunction() {
44   // Each hoisting invalidates a lot of IR around. Just stop the walk after the
45   // first if/else hoisting, and repeat until no more hoisting can be done, or
46   // the maximum number of iterations have been run.
47   auto func = getFunction();
48   unsigned i = 0;
49   do {
50     auto walkFn = [](AffineIfOp op) {
51       return succeeded(hoistAffineIfOp(op)) ? WalkResult::interrupt()
52                                             : WalkResult::advance();
53     };
54     if (func.walk(walkFn).wasInterrupted())
55       break;
56   } while (++i < kMaxIterations);
57 }
58 
59 namespace mlir {
60 void registerTestAffineLoopUnswitchingPass() {
61   PassRegistration<TestAffineLoopUnswitching>();
62 }
63 } // namespace mlir
64