CGLoopInfo.h revision 360784 
1//===---- CGLoopInfo.h - LLVM CodeGen for loop metadata -*- 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//
9// This is the internal state used for llvm translation for loop statement
10// metadata.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_LIB_CODEGEN_CGLOOPINFO_H
15#define LLVM_CLANG_LIB_CODEGEN_CGLOOPINFO_H
16
17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/IR/DebugLoc.h"
20#include "llvm/IR/Value.h"
21#include "llvm/Support/Compiler.h"
22
23namespace llvm {
24class BasicBlock;
25class Instruction;
26class MDNode;
27} // end namespace llvm
28
29namespace clang {
30class Attr;
31class ASTContext;
32namespace CodeGen {
33
34/// Attributes that may be specified on loops.
35struct LoopAttributes {
36  explicit LoopAttributes(bool IsParallel = false);
37  void clear();
38
39  /// Generate llvm.loop.parallel metadata for loads and stores.
40  bool IsParallel;
41
42  /// State of loop vectorization or unrolling.
43  enum LVEnableState { Unspecified, Enable, Disable, Full };
44
45  /// Value for llvm.loop.vectorize.enable metadata.
46  LVEnableState VectorizeEnable;
47
48  /// Value for llvm.loop.unroll.* metadata (enable, disable, or full).
49  LVEnableState UnrollEnable;
50
51  /// Value for llvm.loop.unroll_and_jam.* metadata (enable, disable, or full).
52  LVEnableState UnrollAndJamEnable;
53
54  /// Value for llvm.loop.vectorize.predicate metadata
55  LVEnableState VectorizePredicateEnable;
56
57  /// Value for llvm.loop.vectorize.width metadata.
58  unsigned VectorizeWidth;
59
60  /// Value for llvm.loop.interleave.count metadata.
61  unsigned InterleaveCount;
62
63  /// llvm.unroll.
64  unsigned UnrollCount;
65
66  /// llvm.unroll.
67  unsigned UnrollAndJamCount;
68
69  /// Value for llvm.loop.distribute.enable metadata.
70  LVEnableState DistributeEnable;
71
72  /// Value for llvm.loop.pipeline.disable metadata.
73  bool PipelineDisabled;
74
75  /// Value for llvm.loop.pipeline.iicount metadata.
76  unsigned PipelineInitiationInterval;
77};
78
79/// Information used when generating a structured loop.
80class LoopInfo {
81public:
82  /// Construct a new LoopInfo for the loop with entry Header.
83  LoopInfo(llvm::BasicBlock *Header, const LoopAttributes &Attrs,
84           const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc,
85           LoopInfo *Parent);
86
87  /// Get the loop id metadata for this loop.
88  llvm::MDNode *getLoopID() const { return TempLoopID.get(); }
89
90  /// Get the header block of this loop.
91  llvm::BasicBlock *getHeader() const { return Header; }
92
93  /// Get the set of attributes active for this loop.
94  const LoopAttributes &getAttributes() const { return Attrs; }
95
96  /// Return this loop's access group or nullptr if it does not have one.
97  llvm::MDNode *getAccessGroup() const { return AccGroup; }
98
99  /// Create the loop's metadata. Must be called after its nested loops have
100  /// been processed.
101  void finish();
102
103private:
104  /// Loop ID metadata.
105  llvm::TempMDTuple TempLoopID;
106  /// Header block of this loop.
107  llvm::BasicBlock *Header;
108  /// The attributes for this loop.
109  LoopAttributes Attrs;
110  /// The access group for memory accesses parallel to this loop.
111  llvm::MDNode *AccGroup = nullptr;
112  /// Start location of this loop.
113  llvm::DebugLoc StartLoc;
114  /// End location of this loop.
115  llvm::DebugLoc EndLoc;
116  /// The next outer loop, or nullptr if this is the outermost loop.
117  LoopInfo *Parent;
118  /// If this loop has unroll-and-jam metadata, this can be set by the inner
119  /// loop's LoopInfo to set the llvm.loop.unroll_and_jam.followup_inner
120  /// metadata.
121  llvm::MDNode *UnrollAndJamInnerFollowup = nullptr;
122
123  /// Create a LoopID without any transformations.
124  llvm::MDNode *
125  createLoopPropertiesMetadata(llvm::ArrayRef<llvm::Metadata *> LoopProperties);
126
127  /// Create a LoopID for transformations.
128  ///
129  /// The methods call each other in case multiple transformations are applied
130  /// to a loop. The transformation first to be applied will use LoopID of the
131  /// next transformation in its followup attribute.
132  ///
133  /// @param Attrs             The loop's transformations.
134  /// @param LoopProperties    Non-transformation properties such as debug
135  ///                          location, parallel accesses and disabled
136  ///                          transformations. These are added to the returned
137  ///                          LoopID.
138  /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes
139  ///                          at least one transformation.
140  ///
141  /// @return A LoopID (metadata node) that can be used for the llvm.loop
142  ///         annotation or followup-attribute.
143  /// @{
144  llvm::MDNode *
145  createPipeliningMetadata(const LoopAttributes &Attrs,
146                           llvm::ArrayRef<llvm::Metadata *> LoopProperties,
147                           bool &HasUserTransforms);
148  llvm::MDNode *
149  createPartialUnrollMetadata(const LoopAttributes &Attrs,
150                              llvm::ArrayRef<llvm::Metadata *> LoopProperties,
151                              bool &HasUserTransforms);
152  llvm::MDNode *
153  createUnrollAndJamMetadata(const LoopAttributes &Attrs,
154                             llvm::ArrayRef<llvm::Metadata *> LoopProperties,
155                             bool &HasUserTransforms);
156  llvm::MDNode *
157  createLoopVectorizeMetadata(const LoopAttributes &Attrs,
158                              llvm::ArrayRef<llvm::Metadata *> LoopProperties,
159                              bool &HasUserTransforms);
160  llvm::MDNode *
161  createLoopDistributeMetadata(const LoopAttributes &Attrs,
162                               llvm::ArrayRef<llvm::Metadata *> LoopProperties,
163                               bool &HasUserTransforms);
164  llvm::MDNode *
165  createFullUnrollMetadata(const LoopAttributes &Attrs,
166                           llvm::ArrayRef<llvm::Metadata *> LoopProperties,
167                           bool &HasUserTransforms);
168  /// @}
169
170  /// Create a LoopID for this loop, including transformation-unspecific
171  /// metadata such as debug location.
172  ///
173  /// @param Attrs             This loop's attributes and transformations.
174  /// @param LoopProperties    Additional non-transformation properties to add
175  ///                          to the LoopID, such as transformation-specific
176  ///                          metadata that are not covered by @p Attrs.
177  /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes
178  ///                          at least one transformation.
179  ///
180  /// @return A LoopID (metadata node) that can be used for the llvm.loop
181  ///         annotation.
182  llvm::MDNode *createMetadata(const LoopAttributes &Attrs,
183                               llvm::ArrayRef<llvm::Metadata *> LoopProperties,
184                               bool &HasUserTransforms);
185};
186
187/// A stack of loop information corresponding to loop nesting levels.
188/// This stack can be used to prepare attributes which are applied when a loop
189/// is emitted.
190class LoopInfoStack {
191  LoopInfoStack(const LoopInfoStack &) = delete;
192  void operator=(const LoopInfoStack &) = delete;
193
194public:
195  LoopInfoStack() {}
196
197  /// Begin a new structured loop. The set of staged attributes will be
198  /// applied to the loop and then cleared.
199  void push(llvm::BasicBlock *Header, const llvm::DebugLoc &StartLoc,
200            const llvm::DebugLoc &EndLoc);
201
202  /// Begin a new structured loop. Stage attributes from the Attrs list.
203  /// The staged attributes are applied to the loop and then cleared.
204  void push(llvm::BasicBlock *Header, clang::ASTContext &Ctx,
205            llvm::ArrayRef<const Attr *> Attrs, const llvm::DebugLoc &StartLoc,
206            const llvm::DebugLoc &EndLoc);
207
208  /// End the current loop.
209  void pop();
210
211  /// Return the top loop id metadata.
212  llvm::MDNode *getCurLoopID() const { return getInfo().getLoopID(); }
213
214  /// Return true if the top loop is parallel.
215  bool getCurLoopParallel() const {
216    return hasInfo() ? getInfo().getAttributes().IsParallel : false;
217  }
218
219  /// Function called by the CodeGenFunction when an instruction is
220  /// created.
221  void InsertHelper(llvm::Instruction *I) const;
222
223  /// Set the next pushed loop as parallel.
224  void setParallel(bool Enable = true) { StagedAttrs.IsParallel = Enable; }
225
226  /// Set the next pushed loop 'vectorize.enable'
227  void setVectorizeEnable(bool Enable = true) {
228    StagedAttrs.VectorizeEnable =
229        Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
230  }
231
232  /// Set the next pushed loop as a distribution candidate.
233  void setDistributeState(bool Enable = true) {
234    StagedAttrs.DistributeEnable =
235        Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
236  }
237
238  /// Set the next pushed loop unroll state.
239  void setUnrollState(const LoopAttributes::LVEnableState &State) {
240    StagedAttrs.UnrollEnable = State;
241  }
242
243  /// Set the next pushed vectorize predicate state.
244  void setVectorizePredicateState(const LoopAttributes::LVEnableState &State) {
245    StagedAttrs.VectorizePredicateEnable = State;
246  }
247
248  /// Set the next pushed loop unroll_and_jam state.
249  void setUnrollAndJamState(const LoopAttributes::LVEnableState &State) {
250    StagedAttrs.UnrollAndJamEnable = State;
251  }
252
253  /// Set the vectorize width for the next loop pushed.
254  void setVectorizeWidth(unsigned W) { StagedAttrs.VectorizeWidth = W; }
255
256  /// Set the interleave count for the next loop pushed.
257  void setInterleaveCount(unsigned C) { StagedAttrs.InterleaveCount = C; }
258
259  /// Set the unroll count for the next loop pushed.
260  void setUnrollCount(unsigned C) { StagedAttrs.UnrollCount = C; }
261
262  /// \brief Set the unroll count for the next loop pushed.
263  void setUnrollAndJamCount(unsigned C) { StagedAttrs.UnrollAndJamCount = C; }
264
265  /// Set the pipeline disabled state.
266  void setPipelineDisabled(bool S) { StagedAttrs.PipelineDisabled = S; }
267
268  /// Set the pipeline initiation interval.
269  void setPipelineInitiationInterval(unsigned C) {
270    StagedAttrs.PipelineInitiationInterval = C;
271  }
272
273private:
274  /// Returns true if there is LoopInfo on the stack.
275  bool hasInfo() const { return !Active.empty(); }
276  /// Return the LoopInfo for the current loop. HasInfo should be called
277  /// first to ensure LoopInfo is present.
278  const LoopInfo &getInfo() const { return *Active.back(); }
279  /// The set of attributes that will be applied to the next pushed loop.
280  LoopAttributes StagedAttrs;
281  /// Stack of active loops.
282  llvm::SmallVector<std::unique_ptr<LoopInfo>, 4> Active;
283};
284
285} // end namespace CodeGen
286} // end namespace clang
287
288#endif
289