MLIR  19.0.0git
ViewOpGraph.cpp
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1 //===- ViewOpGraph.cpp - View/write op graphviz graphs --------------------===//
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 
10 
12 #include "mlir/IR/Block.h"
13 #include "mlir/IR/BuiltinTypes.h"
14 #include "mlir/IR/Operation.h"
15 #include "mlir/Pass/Pass.h"
17 #include "llvm/Support/Format.h"
18 #include "llvm/Support/GraphWriter.h"
19 #include <map>
20 #include <optional>
21 #include <utility>
22 
23 namespace mlir {
24 #define GEN_PASS_DEF_VIEWOPGRAPH
25 #include "mlir/Transforms/Passes.h.inc"
26 } // namespace mlir
27 
28 using namespace mlir;
29 
30 static const StringRef kLineStyleControlFlow = "dashed";
31 static const StringRef kLineStyleDataFlow = "solid";
32 static const StringRef kShapeNode = "ellipse";
33 static const StringRef kShapeNone = "plain";
34 
35 /// Return the size limits for eliding large attributes.
36 static int64_t getLargeAttributeSizeLimit() {
37  // Use the default from the printer flags if possible.
38  if (std::optional<int64_t> limit =
39  OpPrintingFlags().getLargeElementsAttrLimit())
40  return *limit;
41  return 16;
42 }
43 
44 /// Return all values printed onto a stream as a string.
45 static std::string strFromOs(function_ref<void(raw_ostream &)> func) {
46  std::string buf;
47  llvm::raw_string_ostream os(buf);
48  func(os);
49  return os.str();
50 }
51 
52 /// Escape special characters such as '\n' and quotation marks.
53 static std::string escapeString(std::string str) {
54  return strFromOs([&](raw_ostream &os) { os.write_escaped(str); });
55 }
56 
57 /// Put quotation marks around a given string.
58 static std::string quoteString(const std::string &str) {
59  return "\"" + str + "\"";
60 }
61 
62 using AttributeMap = std::map<std::string, std::string>;
63 
64 namespace {
65 
66 /// This struct represents a node in the DOT language. Each node has an
67 /// identifier and an optional identifier for the cluster (subgraph) that
68 /// contains the node.
69 /// Note: In the DOT language, edges can be drawn only from nodes to nodes, but
70 /// not between clusters. However, edges can be clipped to the boundary of a
71 /// cluster with `lhead` and `ltail` attributes. Therefore, when creating a new
72 /// cluster, an invisible "anchor" node is created.
73 struct Node {
74 public:
75  Node(int id = 0, std::optional<int> clusterId = std::nullopt)
76  : id(id), clusterId(clusterId) {}
77 
78  int id;
79  std::optional<int> clusterId;
80 };
81 
82 /// This pass generates a Graphviz dataflow visualization of an MLIR operation.
83 /// Note: See https://www.graphviz.org/doc/info/lang.html for more information
84 /// about the Graphviz DOT language.
85 class PrintOpPass : public impl::ViewOpGraphBase<PrintOpPass> {
86 public:
87  PrintOpPass(raw_ostream &os) : os(os) {}
88  PrintOpPass(const PrintOpPass &o) : PrintOpPass(o.os.getOStream()) {}
89 
90  void runOnOperation() override {
91  initColorMapping(*getOperation());
92  emitGraph([&]() {
93  processOperation(getOperation());
94  emitAllEdgeStmts();
95  });
96  }
97 
98  /// Create a CFG graph for a region. Used in `Region::viewGraph`.
99  void emitRegionCFG(Region &region) {
100  printControlFlowEdges = true;
101  printDataFlowEdges = false;
102  initColorMapping(region);
103  emitGraph([&]() { processRegion(region); });
104  }
105 
106 private:
107  /// Generate a color mapping that will color every operation with the same
108  /// name the same way. It'll interpolate the hue in the HSV color-space,
109  /// attempting to keep the contrast suitable for black text.
110  template <typename T>
111  void initColorMapping(T &irEntity) {
112  backgroundColors.clear();
114  irEntity.walk([&](Operation *op) {
115  auto &entry = backgroundColors[op->getName()];
116  if (entry.first == 0)
117  ops.push_back(op);
118  ++entry.first;
119  });
120  for (auto indexedOps : llvm::enumerate(ops)) {
121  double hue = ((double)indexedOps.index()) / ops.size();
122  backgroundColors[indexedOps.value()->getName()].second =
123  std::to_string(hue) + " 1.0 1.0";
124  }
125  }
126 
127  /// Emit all edges. This function should be called after all nodes have been
128  /// emitted.
129  void emitAllEdgeStmts() {
130  if (printDataFlowEdges) {
131  for (const auto &[value, node, label] : dataFlowEdges) {
132  emitEdgeStmt(valueToNode[value], node, label, kLineStyleDataFlow);
133  }
134  }
135 
136  for (const std::string &edge : edges)
137  os << edge << ";\n";
138  edges.clear();
139  }
140 
141  /// Emit a cluster (subgraph). The specified builder generates the body of the
142  /// cluster. Return the anchor node of the cluster.
143  Node emitClusterStmt(function_ref<void()> builder, std::string label = "") {
144  int clusterId = ++counter;
145  os << "subgraph cluster_" << clusterId << " {\n";
146  os.indent();
147  // Emit invisible anchor node from/to which arrows can be drawn.
148  Node anchorNode = emitNodeStmt(" ", kShapeNone);
149  os << attrStmt("label", quoteString(escapeString(std::move(label))))
150  << ";\n";
151  builder();
152  os.unindent();
153  os << "}\n";
154  return Node(anchorNode.id, clusterId);
155  }
156 
157  /// Generate an attribute statement.
158  std::string attrStmt(const Twine &key, const Twine &value) {
159  return (key + " = " + value).str();
160  }
161 
162  /// Emit an attribute list.
163  void emitAttrList(raw_ostream &os, const AttributeMap &map) {
164  os << "[";
165  interleaveComma(map, os, [&](const auto &it) {
166  os << this->attrStmt(it.first, it.second);
167  });
168  os << "]";
169  }
170 
171  // Print an MLIR attribute to `os`. Large attributes are truncated.
172  void emitMlirAttr(raw_ostream &os, Attribute attr) {
173  // A value used to elide large container attribute.
174  int64_t largeAttrLimit = getLargeAttributeSizeLimit();
175 
176  // Always emit splat attributes.
177  if (isa<SplatElementsAttr>(attr)) {
178  attr.print(os);
179  return;
180  }
181 
182  // Elide "big" elements attributes.
183  auto elements = dyn_cast<ElementsAttr>(attr);
184  if (elements && elements.getNumElements() > largeAttrLimit) {
185  os << std::string(elements.getShapedType().getRank(), '[') << "..."
186  << std::string(elements.getShapedType().getRank(), ']') << " : "
187  << elements.getType();
188  return;
189  }
190 
191  auto array = dyn_cast<ArrayAttr>(attr);
192  if (array && static_cast<int64_t>(array.size()) > largeAttrLimit) {
193  os << "[...]";
194  return;
195  }
196 
197  // Print all other attributes.
198  std::string buf;
199  llvm::raw_string_ostream ss(buf);
200  attr.print(ss);
201  os << truncateString(ss.str());
202  }
203 
204  /// Append an edge to the list of edges.
205  /// Note: Edges are written to the output stream via `emitAllEdgeStmts`.
206  void emitEdgeStmt(Node n1, Node n2, std::string label, StringRef style) {
207  AttributeMap attrs;
208  attrs["style"] = style.str();
209  // Do not label edges that start/end at a cluster boundary. Such edges are
210  // clipped at the boundary, but labels are not. This can lead to labels
211  // floating around without any edge next to them.
212  if (!n1.clusterId && !n2.clusterId)
213  attrs["label"] = quoteString(escapeString(std::move(label)));
214  // Use `ltail` and `lhead` to draw edges between clusters.
215  if (n1.clusterId)
216  attrs["ltail"] = "cluster_" + std::to_string(*n1.clusterId);
217  if (n2.clusterId)
218  attrs["lhead"] = "cluster_" + std::to_string(*n2.clusterId);
219 
220  edges.push_back(strFromOs([&](raw_ostream &os) {
221  os << llvm::format("v%i -> v%i ", n1.id, n2.id);
222  emitAttrList(os, attrs);
223  }));
224  }
225 
226  /// Emit a graph. The specified builder generates the body of the graph.
227  void emitGraph(function_ref<void()> builder) {
228  os << "digraph G {\n";
229  os.indent();
230  // Edges between clusters are allowed only in compound mode.
231  os << attrStmt("compound", "true") << ";\n";
232  builder();
233  os.unindent();
234  os << "}\n";
235  }
236 
237  /// Emit a node statement.
238  Node emitNodeStmt(std::string label, StringRef shape = kShapeNode,
239  StringRef background = "") {
240  int nodeId = ++counter;
241  AttributeMap attrs;
242  attrs["label"] = quoteString(escapeString(std::move(label)));
243  attrs["shape"] = shape.str();
244  if (!background.empty()) {
245  attrs["style"] = "filled";
246  attrs["fillcolor"] = ("\"" + background + "\"").str();
247  }
248  os << llvm::format("v%i ", nodeId);
249  emitAttrList(os, attrs);
250  os << ";\n";
251  return Node(nodeId);
252  }
253 
254  /// Generate a label for an operation.
255  std::string getLabel(Operation *op) {
256  return strFromOs([&](raw_ostream &os) {
257  // Print operation name and type.
258  os << op->getName();
259  if (printResultTypes) {
260  os << " : (";
261  std::string buf;
262  llvm::raw_string_ostream ss(buf);
263  interleaveComma(op->getResultTypes(), ss);
264  os << truncateString(ss.str()) << ")";
265  }
266 
267  // Print attributes.
268  if (printAttrs) {
269  os << "\n";
270  for (const NamedAttribute &attr : op->getAttrs()) {
271  os << '\n' << attr.getName().getValue() << ": ";
272  emitMlirAttr(os, attr.getValue());
273  }
274  }
275  });
276  }
277 
278  /// Generate a label for a block argument.
279  std::string getLabel(BlockArgument arg) {
280  return "arg" + std::to_string(arg.getArgNumber());
281  }
282 
283  /// Process a block. Emit a cluster and one node per block argument and
284  /// operation inside the cluster.
285  void processBlock(Block &block) {
286  emitClusterStmt([&]() {
287  for (BlockArgument &blockArg : block.getArguments())
288  valueToNode[blockArg] = emitNodeStmt(getLabel(blockArg));
289 
290  // Emit a node for each operation.
291  std::optional<Node> prevNode;
292  for (Operation &op : block) {
293  Node nextNode = processOperation(&op);
294  if (printControlFlowEdges && prevNode)
295  emitEdgeStmt(*prevNode, nextNode, /*label=*/"",
297  prevNode = nextNode;
298  }
299  });
300  }
301 
302  /// Process an operation. If the operation has regions, emit a cluster.
303  /// Otherwise, emit a node.
304  Node processOperation(Operation *op) {
305  Node node;
306  if (op->getNumRegions() > 0) {
307  // Emit cluster for op with regions.
308  node = emitClusterStmt(
309  [&]() {
310  for (Region &region : op->getRegions())
311  processRegion(region);
312  },
313  getLabel(op));
314  } else {
315  node = emitNodeStmt(getLabel(op), kShapeNode,
316  backgroundColors[op->getName()].second);
317  }
318 
319  // Insert data flow edges originating from each operand.
320  if (printDataFlowEdges) {
321  unsigned numOperands = op->getNumOperands();
322  for (unsigned i = 0; i < numOperands; i++)
323  dataFlowEdges.push_back({op->getOperand(i), node,
324  numOperands == 1 ? "" : std::to_string(i)});
325  }
326 
327  for (Value result : op->getResults())
328  valueToNode[result] = node;
329 
330  return node;
331  }
332 
333  /// Process a region.
334  void processRegion(Region &region) {
335  for (Block &block : region.getBlocks())
336  processBlock(block);
337  }
338 
339  /// Truncate long strings.
340  std::string truncateString(std::string str) {
341  if (str.length() <= maxLabelLen)
342  return str;
343  return str.substr(0, maxLabelLen) + "...";
344  }
345 
346  /// Output stream to write DOT file to.
348  /// A list of edges. For simplicity, should be emitted after all nodes were
349  /// emitted.
350  std::vector<std::string> edges;
351  /// Mapping of SSA values to Graphviz nodes/clusters.
352  DenseMap<Value, Node> valueToNode;
353  /// Output for data flow edges is delayed until the end to handle cycles
354  std::vector<std::tuple<Value, Node, std::string>> dataFlowEdges;
355  /// Counter for generating unique node/subgraph identifiers.
356  int counter = 0;
357 
359 };
360 
361 } // namespace
362 
363 std::unique_ptr<Pass> mlir::createPrintOpGraphPass(raw_ostream &os) {
364  return std::make_unique<PrintOpPass>(os);
365 }
366 
367 /// Generate a CFG for a region and show it in a window.
368 static void llvmViewGraph(Region &region, const Twine &name) {
369  int fd;
370  std::string filename = llvm::createGraphFilename(name.str(), fd);
371  {
372  llvm::raw_fd_ostream os(fd, /*shouldClose=*/true);
373  if (fd == -1) {
374  llvm::errs() << "error opening file '" << filename << "' for writing\n";
375  return;
376  }
377  PrintOpPass pass(os);
378  pass.emitRegionCFG(region);
379  }
380  llvm::DisplayGraph(filename, /*wait=*/false, llvm::GraphProgram::DOT);
381 }
382 
383 void mlir::Region::viewGraph(const Twine &regionName) {
384  llvmViewGraph(*this, regionName);
385 }
386 
387 void mlir::Region::viewGraph() { viewGraph("region"); }
MemRefDependenceGraph::Node Node
Definition: Utils.cpp:38
static std::string quoteString(const std::string &str)
Put quotation marks around a given string.
Definition: ViewOpGraph.cpp:58
static const StringRef kLineStyleDataFlow
Definition: ViewOpGraph.cpp:31
static const StringRef kLineStyleControlFlow
Definition: ViewOpGraph.cpp:30
static int64_t getLargeAttributeSizeLimit()
Return the size limits for eliding large attributes.
Definition: ViewOpGraph.cpp:36
std::map< std::string, std::string > AttributeMap
Definition: ViewOpGraph.cpp:62
static const StringRef kShapeNone
Definition: ViewOpGraph.cpp:33
static const StringRef kShapeNode
Definition: ViewOpGraph.cpp:32
static void llvmViewGraph(Region &region, const Twine &name)
Generate a CFG for a region and show it in a window.
static std::string escapeString(std::string str)
Escape special characters such as ' ' and quotation marks.
Definition: ViewOpGraph.cpp:53
static std::string strFromOs(function_ref< void(raw_ostream &)> func)
Return all values printed onto a stream as a string.
Definition: ViewOpGraph.cpp:45
Attributes are known-constant values of operations.
Definition: Attributes.h:25
void print(raw_ostream &os, bool elideType=false) const
Print the attribute.
This class represents an argument of a Block.
Definition: Value.h:319
unsigned getArgNumber() const
Returns the number of this argument.
Definition: Value.h:331
Block represents an ordered list of Operations.
Definition: Block.h:31
BlockArgListType getArguments()
Definition: Block.h:85
NamedAttribute represents a combination of a name and an Attribute value.
Definition: Attributes.h:207
Set of flags used to control the behavior of the various IR print methods (e.g.
Operation is the basic unit of execution within MLIR.
Definition: Operation.h:88
unsigned getNumRegions()
Returns the number of regions held by this operation.
Definition: Operation.h:669
unsigned getNumOperands()
Definition: Operation.h:341
ArrayRef< NamedAttribute > getAttrs()
Return all of the attributes on this operation.
Definition: Operation.h:507
MutableArrayRef< Region > getRegions()
Returns the regions held by this operation.
Definition: Operation.h:672
OperationName getName()
The name of an operation is the key identifier for it.
Definition: Operation.h:119
result_type_range getResultTypes()
Definition: Operation.h:423
result_range getResults()
Definition: Operation.h:410
This class contains a list of basic blocks and a link to the parent operation it is attached to.
Definition: Region.h:26
BlockListType & getBlocks()
Definition: Region.h:45
void viewGraph()
This class represents an instance of an SSA value in the MLIR system, representing a computable value...
Definition: Value.h:96
raw_ostream subclass that simplifies indention a sequence of code.
constexpr void enumerate(std::tuple< Tys... > &tuple, CallbackT &&callback)
Definition: Matchers.h:285
Include the generated interface declarations.
std::unique_ptr< Pass > createPrintOpGraphPass(raw_ostream &os=llvm::errs())
Creates a pass to print op graphs.