CGLoopInfo.h revision 355940 
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.width metadata.
55  unsigned VectorizeWidth;
56
57  /// Value for llvm.loop.interleave.count metadata.
58  unsigned InterleaveCount;
59
60  /// llvm.unroll.
61  unsigned UnrollCount;
62
63  /// llvm.unroll.
64  unsigned UnrollAndJamCount;
65
66  /// Value for llvm.loop.distribute.enable metadata.
67  LVEnableState DistributeEnable;
68
69  /// Value for llvm.loop.pipeline.disable metadata.
70  bool PipelineDisabled;
71
72  /// Value for llvm.loop.pipeline.iicount metadata.
73  unsigned PipelineInitiationInterval;
74};
75
76/// Information used when generating a structured loop.
77class LoopInfo {
78public:
79  /// Construct a new LoopInfo for the loop with entry Header.
80  LoopInfo(llvm::BasicBlock *Header, const LoopAttributes &Attrs,
81           const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc,
82           LoopInfo *Parent);
83
84  /// Get the loop id metadata for this loop.
85  llvm::MDNode *getLoopID() const { return TempLoopID.get(); }
86
87  /// Get the header block of this loop.
88  llvm::BasicBlock *getHeader() const { return Header; }
89
90  /// Get the set of attributes active for this loop.
91  const LoopAttributes &getAttributes() const { return Attrs; }
92
93  /// Return this loop's access group or nullptr if it does not have one.
94  llvm::MDNode *getAccessGroup() const { return AccGroup; }
95
96  /// Create the loop's metadata. Must be called after its nested loops have
97  /// been processed.
98  void finish();
99
100private:
101  /// Loop ID metadata.
102  llvm::TempMDTuple TempLoopID;
103  /// Header block of this loop.
104  llvm::BasicBlock *Header;
105  /// The attributes for this loop.
106  LoopAttributes Attrs;
107  /// The access group for memory accesses parallel to this loop.
108  llvm::MDNode *AccGroup = nullptr;
109  /// Start location of this loop.
110  llvm::DebugLoc StartLoc;
111  /// End location of this loop.
112  llvm::DebugLoc EndLoc;
113  /// The next outer loop, or nullptr if this is the outermost loop.
114  LoopInfo *Parent;
115  /// If this loop has unroll-and-jam metadata, this can be set by the inner
116  /// loop's LoopInfo to set the llvm.loop.unroll_and_jam.followup_inner
117  /// metadata.
118  llvm::MDNode *UnrollAndJamInnerFollowup = nullptr;
119
120  /// Create a LoopID without any transformations.
121  llvm::MDNode *
122  createLoopPropertiesMetadata(llvm::ArrayRef<llvm::Metadata *> LoopProperties);
123
124  /// Create a LoopID for transformations.
125  ///
126  /// The methods call each other in case multiple transformations are applied
127  /// to a loop. The transformation first to be applied will use LoopID of the
128  /// next transformation in its followup attribute.
129  ///
130  /// @param Attrs             The loop's transformations.
131  /// @param LoopProperties    Non-transformation properties such as debug
132  ///                          location, parallel accesses and disabled
133  ///                          transformations. These are added to the returned
134  ///                          LoopID.
135  /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes
136  ///                          at least one transformation.
137  ///
138  /// @return A LoopID (metadata node) that can be used for the llvm.loop
139  ///         annotation or followup-attribute.
140  /// @{
141  llvm::MDNode *
142  createPipeliningMetadata(const LoopAttributes &Attrs,
143                           llvm::ArrayRef<llvm::Metadata *> LoopProperties,
144                           bool &HasUserTransforms);
145  llvm::MDNode *
146  createPartialUnrollMetadata(const LoopAttributes &Attrs,
147                              llvm::ArrayRef<llvm::Metadata *> LoopProperties,
148                              bool &HasUserTransforms);
149  llvm::MDNode *
150  createUnrollAndJamMetadata(const LoopAttributes &Attrs,
151                             llvm::ArrayRef<llvm::Metadata *> LoopProperties,
152                             bool &HasUserTransforms);
153  llvm::MDNode *
154  createLoopVectorizeMetadata(const LoopAttributes &Attrs,
155                              llvm::ArrayRef<llvm::Metadata *> LoopProperties,
156                              bool &HasUserTransforms);
157  llvm::MDNode *
158  createLoopDistributeMetadata(const LoopAttributes &Attrs,
159                               llvm::ArrayRef<llvm::Metadata *> LoopProperties,
160                               bool &HasUserTransforms);
161  llvm::MDNode *
162  createFullUnrollMetadata(const LoopAttributes &Attrs,
163                           llvm::ArrayRef<llvm::Metadata *> LoopProperties,
164                           bool &HasUserTransforms);
165  /// @}
166
167  /// Create a LoopID for this loop, including transformation-unspecific
168  /// metadata such as debug location.
169  ///
170  /// @param Attrs             This loop's attributes and transformations.
171  /// @param LoopProperties    Additional non-transformation properties to add
172  ///                          to the LoopID, such as transformation-specific
173  ///                          metadata that are not covered by @p Attrs.
174  /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes
175  ///                          at least one transformation.
176  ///
177  /// @return A LoopID (metadata node) that can be used for the llvm.loop
178  ///         annotation.
179  llvm::MDNode *createMetadata(const LoopAttributes &Attrs,
180                               llvm::ArrayRef<llvm::Metadata *> LoopProperties,
181                               bool &HasUserTransforms);
182};
183
184/// A stack of loop information corresponding to loop nesting levels.
185/// This stack can be used to prepare attributes which are applied when a loop
186/// is emitted.
187class LoopInfoStack {
188  LoopInfoStack(const LoopInfoStack &) = delete;
189  void operator=(const LoopInfoStack &) = delete;
190
191public:
192  LoopInfoStack() {}
193
194  /// Begin a new structured loop. The set of staged attributes will be
195  /// applied to the loop and then cleared.
196  void push(llvm::BasicBlock *Header, const llvm::DebugLoc &StartLoc,
197            const llvm::DebugLoc &EndLoc);
198
199  /// Begin a new structured loop. Stage attributes from the Attrs list.
200  /// The staged attributes are applied to the loop and then cleared.
201  void push(llvm::BasicBlock *Header, clang::ASTContext &Ctx,
202            llvm::ArrayRef<const Attr *> Attrs, const llvm::DebugLoc &StartLoc,
203            const llvm::DebugLoc &EndLoc);
204
205  /// End the current loop.
206  void pop();
207
208  /// Return the top loop id metadata.
209  llvm::MDNode *getCurLoopID() const { return getInfo().getLoopID(); }
210
211  /// Return true if the top loop is parallel.
212  bool getCurLoopParallel() const {
213    return hasInfo() ? getInfo().getAttributes().IsParallel : false;
214  }
215
216  /// Function called by the CodeGenFunction when an instruction is
217  /// created.
218  void InsertHelper(llvm::Instruction *I) const;
219
220  /// Set the next pushed loop as parallel.
221  void setParallel(bool Enable = true) { StagedAttrs.IsParallel = Enable; }
222
223  /// Set the next pushed loop 'vectorize.enable'
224  void setVectorizeEnable(bool Enable = true) {
225    StagedAttrs.VectorizeEnable =
226        Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
227  }
228
229  /// Set the next pushed loop as a distribution candidate.
230  void setDistributeState(bool Enable = true) {
231    StagedAttrs.DistributeEnable =
232        Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
233  }
234
235  /// Set the next pushed loop unroll state.
236  void setUnrollState(const LoopAttributes::LVEnableState &State) {
237    StagedAttrs.UnrollEnable = State;
238  }
239
240  /// Set the next pushed loop unroll_and_jam state.
241  void setUnrollAndJamState(const LoopAttributes::LVEnableState &State) {
242    StagedAttrs.UnrollAndJamEnable = State;
243  }
244
245  /// Set the vectorize width for the next loop pushed.
246  void setVectorizeWidth(unsigned W) { StagedAttrs.VectorizeWidth = W; }
247
248  /// Set the interleave count for the next loop pushed.
249  void setInterleaveCount(unsigned C) { StagedAttrs.InterleaveCount = C; }
250
251  /// Set the unroll count for the next loop pushed.
252  void setUnrollCount(unsigned C) { StagedAttrs.UnrollCount = C; }
253
254  /// \brief Set the unroll count for the next loop pushed.
255  void setUnrollAndJamCount(unsigned C) { StagedAttrs.UnrollAndJamCount = C; }
256
257  /// Set the pipeline disabled state.
258  void setPipelineDisabled(bool S) { StagedAttrs.PipelineDisabled = S; }
259
260  /// Set the pipeline initiation interval.
261  void setPipelineInitiationInterval(unsigned C) {
262    StagedAttrs.PipelineInitiationInterval = C;
263  }
264
265private:
266  /// Returns true if there is LoopInfo on the stack.
267  bool hasInfo() const { return !Active.empty(); }
268  /// Return the LoopInfo for the current loop. HasInfo should be called
269  /// first to ensure LoopInfo is present.
270  const LoopInfo &getInfo() const { return Active.back(); }
271  /// The set of attributes that will be applied to the next pushed loop.
272  LoopAttributes StagedAttrs;
273  /// Stack of active loops.
274  llvm::SmallVector<LoopInfo, 4> Active;
275};
276
277} // end namespace CodeGen
278} // end namespace clang
279
280#endif
281