1//===- VPlanCFG.h - GraphTraits for VP blocks -------------------*- C++ -*-===//
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/// Specializations of GraphTraits that allow VPBlockBase graphs to be
9/// treated as proper graphs for generic algorithms;
10//===----------------------------------------------------------------------===//
11
12#ifndef LLVM_TRANSFORMS_VECTORIZE_VPLANCFG_H
13#define LLVM_TRANSFORMS_VECTORIZE_VPLANCFG_H
14
15#include "VPlan.h"
16#include "llvm/ADT/DepthFirstIterator.h"
17#include "llvm/ADT/GraphTraits.h"
18#include "llvm/ADT/SmallVector.h"
19
20namespace llvm {
21
22//===----------------------------------------------------------------------===//
23// GraphTraits specializations for VPlan Hierarchical Control-Flow Graphs //
24//===----------------------------------------------------------------------===//
25
26/// Iterator to traverse all successors of a VPBlockBase node. This includes the
27/// entry node of VPRegionBlocks. Exit blocks of a region implicitly have their
28/// parent region's successors. This ensures all blocks in a region are visited
29/// before any blocks in a successor region when doing a reverse post-order
30// traversal of the graph. Region blocks themselves traverse only their entries
31// directly and not their successors. Those will be traversed when a region's
32// exiting block is traversed
33template <typename BlockPtrTy>
34class VPAllSuccessorsIterator
35 : public iterator_facade_base<VPAllSuccessorsIterator<BlockPtrTy>,
36 std::bidirectional_iterator_tag,
37 VPBlockBase> {
38 BlockPtrTy Block;
39 /// Index of the current successor. For VPBasicBlock nodes, this simply is the
40 /// index for the successor array. For VPRegionBlock, SuccessorIdx == 0 is
41 /// used for the region's entry block, and SuccessorIdx - 1 are the indices
42 /// for the successor array.
43 size_t SuccessorIdx;
44
45 static BlockPtrTy getBlockWithSuccs(BlockPtrTy Current) {
46 while (Current && Current->getNumSuccessors() == 0)
47 Current = Current->getParent();
48 return Current;
49 }
50
51 /// Templated helper to dereference successor \p SuccIdx of \p Block. Used by
52 /// both the const and non-const operator* implementations.
53 template <typename T1> static T1 deref(T1 Block, unsigned SuccIdx) {
54 if (auto *R = dyn_cast<VPRegionBlock>(Block)) {
55 assert(SuccIdx == 0);
56 return R->getEntry();
57 }
58
59 // For exit blocks, use the next parent region with successors.
60 return getBlockWithSuccs(Current: Block)->getSuccessors()[SuccIdx];
61 }
62
63public:
64 /// Used by iterator_facade_base with bidirectional_iterator_tag.
65 using reference = BlockPtrTy;
66
67 VPAllSuccessorsIterator(BlockPtrTy Block, size_t Idx = 0)
68 : Block(Block), SuccessorIdx(Idx) {}
69 VPAllSuccessorsIterator(const VPAllSuccessorsIterator &Other)
70 : Block(Other.Block), SuccessorIdx(Other.SuccessorIdx) {}
71
72 VPAllSuccessorsIterator &operator=(const VPAllSuccessorsIterator &R) {
73 Block = R.Block;
74 SuccessorIdx = R.SuccessorIdx;
75 return *this;
76 }
77
78 static VPAllSuccessorsIterator end(BlockPtrTy Block) {
79 if (auto *R = dyn_cast<VPRegionBlock>(Block)) {
80 // Traverse through the region's entry node.
81 return {R, 1};
82 }
83 BlockPtrTy ParentWithSuccs = getBlockWithSuccs(Current: Block);
84 unsigned NumSuccessors =
85 ParentWithSuccs ? ParentWithSuccs->getNumSuccessors() : 0;
86 return {Block, NumSuccessors};
87 }
88
89 bool operator==(const VPAllSuccessorsIterator &R) const {
90 return Block == R.Block && SuccessorIdx == R.SuccessorIdx;
91 }
92
93 const VPBlockBase *operator*() const { return deref(Block, SuccessorIdx); }
94
95 BlockPtrTy operator*() { return deref(Block, SuccessorIdx); }
96
97 VPAllSuccessorsIterator &operator++() {
98 SuccessorIdx++;
99 return *this;
100 }
101
102 VPAllSuccessorsIterator &operator--() {
103 SuccessorIdx--;
104 return *this;
105 }
106
107 VPAllSuccessorsIterator operator++(int X) {
108 VPAllSuccessorsIterator Orig = *this;
109 SuccessorIdx++;
110 return Orig;
111 }
112};
113
114/// Helper for GraphTraits specialization that traverses through VPRegionBlocks.
115template <typename BlockTy> class VPBlockDeepTraversalWrapper {
116 BlockTy Entry;
117
118public:
119 VPBlockDeepTraversalWrapper(BlockTy Entry) : Entry(Entry) {}
120 BlockTy getEntry() { return Entry; }
121};
122
123/// GraphTraits specialization to recursively traverse VPBlockBase nodes,
124/// including traversing through VPRegionBlocks. Exit blocks of a region
125/// implicitly have their parent region's successors. This ensures all blocks in
126/// a region are visited before any blocks in a successor region when doing a
127/// reverse post-order traversal of the graph.
128template <> struct GraphTraits<VPBlockDeepTraversalWrapper<VPBlockBase *>> {
129 using NodeRef = VPBlockBase *;
130 using ChildIteratorType = VPAllSuccessorsIterator<VPBlockBase *>;
131
132 static NodeRef getEntryNode(VPBlockDeepTraversalWrapper<VPBlockBase *> N) {
133 return N.getEntry();
134 }
135
136 static inline ChildIteratorType child_begin(NodeRef N) {
137 return ChildIteratorType(N);
138 }
139
140 static inline ChildIteratorType child_end(NodeRef N) {
141 return ChildIteratorType::end(Block: N);
142 }
143};
144
145template <>
146struct GraphTraits<VPBlockDeepTraversalWrapper<const VPBlockBase *>> {
147 using NodeRef = const VPBlockBase *;
148 using ChildIteratorType = VPAllSuccessorsIterator<const VPBlockBase *>;
149
150 static NodeRef
151 getEntryNode(VPBlockDeepTraversalWrapper<const VPBlockBase *> N) {
152 return N.getEntry();
153 }
154
155 static inline ChildIteratorType child_begin(NodeRef N) {
156 return ChildIteratorType(N);
157 }
158
159 static inline ChildIteratorType child_end(NodeRef N) {
160 return ChildIteratorType::end(Block: N);
161 }
162};
163
164/// Helper for GraphTraits specialization that does not traverses through
165/// VPRegionBlocks.
166template <typename BlockTy> class VPBlockShallowTraversalWrapper {
167 BlockTy Entry;
168
169public:
170 VPBlockShallowTraversalWrapper(BlockTy Entry) : Entry(Entry) {}
171 BlockTy getEntry() { return Entry; }
172};
173
174template <> struct GraphTraits<VPBlockShallowTraversalWrapper<VPBlockBase *>> {
175 using NodeRef = VPBlockBase *;
176 using ChildIteratorType = SmallVectorImpl<VPBlockBase *>::iterator;
177
178 static NodeRef getEntryNode(VPBlockShallowTraversalWrapper<VPBlockBase *> N) {
179 return N.getEntry();
180 }
181
182 static inline ChildIteratorType child_begin(NodeRef N) {
183 return N->getSuccessors().begin();
184 }
185
186 static inline ChildIteratorType child_end(NodeRef N) {
187 return N->getSuccessors().end();
188 }
189};
190
191template <>
192struct GraphTraits<VPBlockShallowTraversalWrapper<const VPBlockBase *>> {
193 using NodeRef = const VPBlockBase *;
194 using ChildIteratorType = SmallVectorImpl<VPBlockBase *>::const_iterator;
195
196 static NodeRef
197 getEntryNode(VPBlockShallowTraversalWrapper<const VPBlockBase *> N) {
198 return N.getEntry();
199 }
200
201 static inline ChildIteratorType child_begin(NodeRef N) {
202 return N->getSuccessors().begin();
203 }
204
205 static inline ChildIteratorType child_end(NodeRef N) {
206 return N->getSuccessors().end();
207 }
208};
209
210/// Returns an iterator range to traverse the graph starting at \p G in
211/// depth-first order. The iterator won't traverse through region blocks.
212inline iterator_range<
213 df_iterator<VPBlockShallowTraversalWrapper<VPBlockBase *>>>
214vp_depth_first_shallow(VPBlockBase *G) {
215 return depth_first(G: VPBlockShallowTraversalWrapper<VPBlockBase *>(G));
216}
217inline iterator_range<
218 df_iterator<VPBlockShallowTraversalWrapper<const VPBlockBase *>>>
219vp_depth_first_shallow(const VPBlockBase *G) {
220 return depth_first(G: VPBlockShallowTraversalWrapper<const VPBlockBase *>(G));
221}
222
223/// Returns an iterator range to traverse the graph starting at \p G in
224/// depth-first order while traversing through region blocks.
225inline iterator_range<df_iterator<VPBlockDeepTraversalWrapper<VPBlockBase *>>>
226vp_depth_first_deep(VPBlockBase *G) {
227 return depth_first(G: VPBlockDeepTraversalWrapper<VPBlockBase *>(G));
228}
229inline iterator_range<
230 df_iterator<VPBlockDeepTraversalWrapper<const VPBlockBase *>>>
231vp_depth_first_deep(const VPBlockBase *G) {
232 return depth_first(G: VPBlockDeepTraversalWrapper<const VPBlockBase *>(G));
233}
234
235// The following set of template specializations implement GraphTraits to treat
236// any VPBlockBase as a node in a graph of VPBlockBases. It's important to note
237// that VPBlockBase traits don't recurse into VPRegioBlocks, i.e., if the
238// VPBlockBase is a VPRegionBlock, this specialization provides access to its
239// successors/predecessors but not to the blocks inside the region.
240
241template <> struct GraphTraits<VPBlockBase *> {
242 using NodeRef = VPBlockBase *;
243 using ChildIteratorType = VPAllSuccessorsIterator<VPBlockBase *>;
244
245 static NodeRef getEntryNode(NodeRef N) { return N; }
246
247 static inline ChildIteratorType child_begin(NodeRef N) {
248 return ChildIteratorType(N);
249 }
250
251 static inline ChildIteratorType child_end(NodeRef N) {
252 return ChildIteratorType::end(Block: N);
253 }
254};
255
256template <> struct GraphTraits<const VPBlockBase *> {
257 using NodeRef = const VPBlockBase *;
258 using ChildIteratorType = VPAllSuccessorsIterator<const VPBlockBase *>;
259
260 static NodeRef getEntryNode(NodeRef N) { return N; }
261
262 static inline ChildIteratorType child_begin(NodeRef N) {
263 return ChildIteratorType(N);
264 }
265
266 static inline ChildIteratorType child_end(NodeRef N) {
267 return ChildIteratorType::end(Block: N);
268 }
269};
270
271/// Inverse graph traits are not implemented yet.
272/// TODO: Implement a version of VPBlockNonRecursiveTraversalWrapper to traverse
273/// predecessors recursively through regions.
274template <> struct GraphTraits<Inverse<VPBlockBase *>> {
275 using NodeRef = VPBlockBase *;
276 using ChildIteratorType = SmallVectorImpl<VPBlockBase *>::iterator;
277
278 static NodeRef getEntryNode(Inverse<NodeRef> B) {
279 llvm_unreachable("not implemented");
280 }
281
282 static inline ChildIteratorType child_begin(NodeRef N) {
283 llvm_unreachable("not implemented");
284 }
285
286 static inline ChildIteratorType child_end(NodeRef N) {
287 llvm_unreachable("not implemented");
288 }
289};
290
291template <> struct GraphTraits<VPlan *> {
292 using GraphRef = VPlan *;
293 using NodeRef = VPBlockBase *;
294 using nodes_iterator = df_iterator<NodeRef>;
295
296 static NodeRef getEntryNode(GraphRef N) { return N->getEntry(); }
297
298 static nodes_iterator nodes_begin(GraphRef N) {
299 return nodes_iterator::begin(G: N->getEntry());
300 }
301
302 static nodes_iterator nodes_end(GraphRef N) {
303 // df_iterator::end() returns an empty iterator so the node used doesn't
304 // matter.
305 return nodes_iterator::end(G: N->getEntry());
306 }
307};
308
309} // namespace llvm
310
311#endif // LLVM_TRANSFORMS_VECTORIZE_VPLANCFG_H
312