1//===- LoopLikeInterface.cpp - Loop-like operations in MLIR ---------------===//
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/Interfaces/LoopLikeInterface.h"
10
11#include "mlir/Interfaces/FunctionInterfaces.h"
12#include "llvm/ADT/DenseSet.h"
13
14using namespace mlir;
15
16/// Include the definitions of the loop-like interfaces.
17#include "mlir/Interfaces/LoopLikeInterface.cpp.inc"
18
19bool LoopLikeOpInterface::blockIsInLoop(Block *block) {
20 Operation *parent = block->getParentOp();
21
22 // The block could be inside a loop-like operation
23 if (isa<LoopLikeOpInterface>(parent) ||
24 parent->getParentOfType<LoopLikeOpInterface>())
25 return true;
26
27 // This block might be nested inside another block, which is in a loop
28 if (!isa<FunctionOpInterface>(parent))
29 if (mlir::Block *parentBlock = parent->getBlock())
30 if (blockIsInLoop(parentBlock))
31 return true;
32
33 // Or the block could be inside a control flow graph loop:
34 // A block is in a control flow graph loop if it can reach itself in a graph
35 // traversal
36 DenseSet<Block *> visited;
37 SmallVector<Block *> stack;
38 stack.push_back(block);
39 while (!stack.empty()) {
40 Block *current = stack.pop_back_val();
41 auto [it, inserted] = visited.insert(current);
42 if (!inserted) {
43 // loop detected
44 if (current == block)
45 return true;
46 continue;
47 }
48
49 stack.reserve(stack.size() + current->getNumSuccessors());
50 for (Block *successor : current->getSuccessors())
51 stack.push_back(successor);
52 }
53 return false;
54}
55
56LogicalResult detail::verifyLoopLikeOpInterface(Operation *op) {
57 // Note: These invariants are also verified by the RegionBranchOpInterface,
58 // but the LoopLikeOpInterface provides better error messages.
59 auto loopLikeOp = cast<LoopLikeOpInterface>(op);
60
61 // Verify number of inits/iter_args/yielded values/loop results.
62 if (loopLikeOp.getInits().size() != loopLikeOp.getRegionIterArgs().size())
63 return op->emitOpError(message: "different number of inits and region iter_args: ")
64 << loopLikeOp.getInits().size()
65 << " != " << loopLikeOp.getRegionIterArgs().size();
66 if (!loopLikeOp.getYieldedValues().empty() &&
67 loopLikeOp.getRegionIterArgs().size() !=
68 loopLikeOp.getYieldedValues().size())
69 return op->emitOpError(
70 message: "different number of region iter_args and yielded values: ")
71 << loopLikeOp.getRegionIterArgs().size()
72 << " != " << loopLikeOp.getYieldedValues().size();
73 if (loopLikeOp.getLoopResults() && loopLikeOp.getLoopResults()->size() !=
74 loopLikeOp.getRegionIterArgs().size())
75 return op->emitOpError(
76 message: "different number of loop results and region iter_args: ")
77 << loopLikeOp.getLoopResults()->size()
78 << " != " << loopLikeOp.getRegionIterArgs().size();
79
80 // Verify types of inits/iter_args/yielded values/loop results.
81 int64_t i = 0;
82 auto yieldedValues = loopLikeOp.getYieldedValues();
83 for (const auto [index, init, regionIterArg] :
84 llvm::enumerate(loopLikeOp.getInits(), loopLikeOp.getRegionIterArgs())) {
85 if (init.getType() != regionIterArg.getType())
86 return op->emitOpError(std::to_string(index))
87 << "-th init and " << index
88 << "-th region iter_arg have different type: " << init.getType()
89 << " != " << regionIterArg.getType();
90 if (!yieldedValues.empty()) {
91 if (regionIterArg.getType() != yieldedValues[index].getType())
92 return op->emitOpError(std::to_string(index))
93 << "-th region iter_arg and " << index
94 << "-th yielded value have different type: "
95 << regionIterArg.getType()
96 << " != " << yieldedValues[index].getType();
97 }
98 ++i;
99 }
100 i = 0;
101 if (loopLikeOp.getLoopResults()) {
102 for (const auto it : llvm::zip_equal(loopLikeOp.getRegionIterArgs(),
103 *loopLikeOp.getLoopResults())) {
104 if (std::get<0>(it).getType() != std::get<1>(it).getType())
105 return op->emitOpError(std::to_string(i))
106 << "-th region iter_arg and " << i
107 << "-th loop result have different type: "
108 << std::get<0>(it).getType()
109 << " != " << std::get<1>(it).getType();
110 }
111 ++i;
112 }
113
114 return success();
115}
116

source code of mlir/lib/Interfaces/LoopLikeInterface.cpp