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;
32class CodeGenOptions;
33namespace CodeGen {
34
35/// Attributes that may be specified on loops.
36struct LoopAttributes {
37 explicit LoopAttributes(bool IsParallel = false);
38 void clear();
39
40 /// Generate llvm.loop.parallel metadata for loads and stores.
41 bool IsParallel;
42
43 /// State of loop vectorization or unrolling.
44 enum LVEnableState { Unspecified, Enable, Disable, Full };
45
46 /// Value for llvm.loop.vectorize.enable metadata.
47 LVEnableState VectorizeEnable;
48
49 /// Value for llvm.loop.unroll.* metadata (enable, disable, or full).
50 LVEnableState UnrollEnable;
51
52 /// Value for llvm.loop.unroll_and_jam.* metadata (enable, disable, or full).
53 LVEnableState UnrollAndJamEnable;
54
55 /// Value for llvm.loop.vectorize.predicate metadata
56 LVEnableState VectorizePredicateEnable;
57
58 /// Value for llvm.loop.vectorize.width metadata.
59 unsigned VectorizeWidth;
60
61 // Value for llvm.loop.vectorize.scalable.enable
62 LVEnableState VectorizeScalable;
63
64 /// Value for llvm.loop.interleave.count metadata.
65 unsigned InterleaveCount;
66
67 /// llvm.unroll.
68 unsigned UnrollCount;
69
70 /// llvm.unroll.
71 unsigned UnrollAndJamCount;
72
73 /// Value for llvm.loop.distribute.enable metadata.
74 LVEnableState DistributeEnable;
75
76 /// Value for llvm.loop.pipeline.disable metadata.
77 bool PipelineDisabled;
78
79 /// Value for llvm.loop.pipeline.iicount metadata.
80 unsigned PipelineInitiationInterval;
81
82 /// Value for 'llvm.loop.align' metadata.
83 unsigned CodeAlign;
84
85 /// Value for whether the loop is required to make progress.
86 bool MustProgress;
87};
88
89/// Information used when generating a structured loop.
90class LoopInfo {
91public:
92 /// Construct a new LoopInfo for the loop with entry Header.
93 LoopInfo(llvm::BasicBlock *Header, const LoopAttributes &Attrs,
94 const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc,
95 LoopInfo *Parent);
96
97 /// Get the loop id metadata for this loop.
98 llvm::MDNode *getLoopID() const { return TempLoopID.get(); }
99
100 /// Get the header block of this loop.
101 llvm::BasicBlock *getHeader() const { return Header; }
102
103 /// Get the set of attributes active for this loop.
104 const LoopAttributes &getAttributes() const { return Attrs; }
105
106 /// Return this loop's access group or nullptr if it does not have one.
107 llvm::MDNode *getAccessGroup() const { return AccGroup; }
108
109 /// Create the loop's metadata. Must be called after its nested loops have
110 /// been processed.
111 void finish();
112
113 /// Returns the first outer loop containing this loop if any, nullptr
114 /// otherwise.
115 const LoopInfo *getParent() const { return Parent; }
116
117private:
118 /// Loop ID metadata.
119 llvm::TempMDTuple TempLoopID;
120 /// Header block of this loop.
121 llvm::BasicBlock *Header;
122 /// The attributes for this loop.
123 LoopAttributes Attrs;
124 /// The access group for memory accesses parallel to this loop.
125 llvm::MDNode *AccGroup = nullptr;
126 /// Start location of this loop.
127 llvm::DebugLoc StartLoc;
128 /// End location of this loop.
129 llvm::DebugLoc EndLoc;
130 /// The next outer loop, or nullptr if this is the outermost loop.
131 LoopInfo *Parent;
132 /// If this loop has unroll-and-jam metadata, this can be set by the inner
133 /// loop's LoopInfo to set the llvm.loop.unroll_and_jam.followup_inner
134 /// metadata.
135 std::optional<llvm::SmallVector<llvm::Metadata *, 4>>
136 UnrollAndJamInnerFollowup;
137
138 /// Create a followup MDNode that has @p LoopProperties as its attributes.
139 llvm::MDNode *
140 createFollowupMetadata(const char *FollowupName,
141 llvm::ArrayRef<llvm::Metadata *> LoopProperties);
142
143 /// Create a metadata list for transformations.
144 ///
145 /// The methods call each other in case multiple transformations are applied
146 /// to a loop. The transformation first to be applied will use metadata list
147 /// of the next transformation in its followup attribute.
148 ///
149 /// @param Attrs The loop's transformations.
150 /// @param LoopProperties Non-transformation properties such as debug
151 /// location, parallel accesses and disabled
152 /// transformations. These are added to the returned
153 /// LoopID.
154 /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes
155 /// at least one transformation.
156 ///
157 /// @return A metadata list that can be used for the llvm.loop annotation or
158 /// followup-attribute.
159 /// @{
160 llvm::SmallVector<llvm::Metadata *, 4>
161 createPipeliningMetadata(const LoopAttributes &Attrs,
162 llvm::ArrayRef<llvm::Metadata *> LoopProperties,
163 bool &HasUserTransforms);
164 llvm::SmallVector<llvm::Metadata *, 4>
165 createPartialUnrollMetadata(const LoopAttributes &Attrs,
166 llvm::ArrayRef<llvm::Metadata *> LoopProperties,
167 bool &HasUserTransforms);
168 llvm::SmallVector<llvm::Metadata *, 4>
169 createUnrollAndJamMetadata(const LoopAttributes &Attrs,
170 llvm::ArrayRef<llvm::Metadata *> LoopProperties,
171 bool &HasUserTransforms);
172 llvm::SmallVector<llvm::Metadata *, 4>
173 createLoopVectorizeMetadata(const LoopAttributes &Attrs,
174 llvm::ArrayRef<llvm::Metadata *> LoopProperties,
175 bool &HasUserTransforms);
176 llvm::SmallVector<llvm::Metadata *, 4>
177 createLoopDistributeMetadata(const LoopAttributes &Attrs,
178 llvm::ArrayRef<llvm::Metadata *> LoopProperties,
179 bool &HasUserTransforms);
180 llvm::SmallVector<llvm::Metadata *, 4>
181 createFullUnrollMetadata(const LoopAttributes &Attrs,
182 llvm::ArrayRef<llvm::Metadata *> LoopProperties,
183 bool &HasUserTransforms);
184
185 /// @}
186
187 /// Create a metadata list for this loop, including transformation-unspecific
188 /// metadata such as debug location.
189 ///
190 /// @param Attrs This loop's attributes and transformations.
191 /// @param LoopProperties Additional non-transformation properties to add
192 /// to the LoopID, such as transformation-specific
193 /// metadata that are not covered by @p Attrs.
194 /// @param HasUserTransforms [out] Set to true if the returned MDNode encodes
195 /// at least one transformation.
196 ///
197 /// @return A metadata list that can be used for the llvm.loop annotation.
198 llvm::SmallVector<llvm::Metadata *, 4>
199 createMetadata(const LoopAttributes &Attrs,
200 llvm::ArrayRef<llvm::Metadata *> LoopProperties,
201 bool &HasUserTransforms);
202};
203
204/// A stack of loop information corresponding to loop nesting levels.
205/// This stack can be used to prepare attributes which are applied when a loop
206/// is emitted.
207class LoopInfoStack {
208 LoopInfoStack(const LoopInfoStack &) = delete;
209 void operator=(const LoopInfoStack &) = delete;
210
211public:
212 LoopInfoStack() {}
213
214 /// Begin a new structured loop. The set of staged attributes will be
215 /// applied to the loop and then cleared.
216 void push(llvm::BasicBlock *Header, const llvm::DebugLoc &StartLoc,
217 const llvm::DebugLoc &EndLoc);
218
219 /// Begin a new structured loop. Stage attributes from the Attrs list.
220 /// The staged attributes are applied to the loop and then cleared.
221 void push(llvm::BasicBlock *Header, clang::ASTContext &Ctx,
222 const clang::CodeGenOptions &CGOpts,
223 llvm::ArrayRef<const Attr *> Attrs, const llvm::DebugLoc &StartLoc,
224 const llvm::DebugLoc &EndLoc, bool MustProgress = false);
225
226 /// End the current loop.
227 void pop();
228
229 /// Return the top loop id metadata.
230 llvm::MDNode *getCurLoopID() const { return getInfo().getLoopID(); }
231
232 /// Return true if the top loop is parallel.
233 bool getCurLoopParallel() const {
234 return hasInfo() ? getInfo().getAttributes().IsParallel : false;
235 }
236
237 /// Function called by the CodeGenFunction when an instruction is
238 /// created.
239 void InsertHelper(llvm::Instruction *I) const;
240
241 /// Set the next pushed loop as parallel.
242 void setParallel(bool Enable = true) { StagedAttrs.IsParallel = Enable; }
243
244 /// Set the next pushed loop 'vectorize.enable'
245 void setVectorizeEnable(bool Enable = true) {
246 StagedAttrs.VectorizeEnable =
247 Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
248 }
249
250 /// Set the next pushed loop as a distribution candidate.
251 void setDistributeState(bool Enable = true) {
252 StagedAttrs.DistributeEnable =
253 Enable ? LoopAttributes::Enable : LoopAttributes::Disable;
254 }
255
256 /// Set the next pushed loop unroll state.
257 void setUnrollState(const LoopAttributes::LVEnableState &State) {
258 StagedAttrs.UnrollEnable = State;
259 }
260
261 /// Set the next pushed vectorize predicate state.
262 void setVectorizePredicateState(const LoopAttributes::LVEnableState &State) {
263 StagedAttrs.VectorizePredicateEnable = State;
264 }
265
266 /// Set the next pushed loop unroll_and_jam state.
267 void setUnrollAndJamState(const LoopAttributes::LVEnableState &State) {
268 StagedAttrs.UnrollAndJamEnable = State;
269 }
270
271 /// Set the vectorize width for the next loop pushed.
272 void setVectorizeWidth(unsigned W) { StagedAttrs.VectorizeWidth = W; }
273
274 void setVectorizeScalable(const LoopAttributes::LVEnableState &State) {
275 StagedAttrs.VectorizeScalable = State;
276 }
277
278 /// Set the interleave count for the next loop pushed.
279 void setInterleaveCount(unsigned C) { StagedAttrs.InterleaveCount = C; }
280
281 /// Set the unroll count for the next loop pushed.
282 void setUnrollCount(unsigned C) { StagedAttrs.UnrollCount = C; }
283
284 /// \brief Set the unroll count for the next loop pushed.
285 void setUnrollAndJamCount(unsigned C) { StagedAttrs.UnrollAndJamCount = C; }
286
287 /// Set the pipeline disabled state.
288 void setPipelineDisabled(bool S) { StagedAttrs.PipelineDisabled = S; }
289
290 /// Set the pipeline initiation interval.
291 void setPipelineInitiationInterval(unsigned C) {
292 StagedAttrs.PipelineInitiationInterval = C;
293 }
294
295 /// Set value of code align for the next loop pushed.
296 void setCodeAlign(unsigned C) { StagedAttrs.CodeAlign = C; }
297
298 /// Set no progress for the next loop pushed.
299 void setMustProgress(bool P) { StagedAttrs.MustProgress = P; }
300
301 /// Returns true if there is LoopInfo on the stack.
302 bool hasInfo() const { return !Active.empty(); }
303 /// Return the LoopInfo for the current loop. HasInfo should be called
304 /// first to ensure LoopInfo is present.
305 const LoopInfo &getInfo() const { return *Active.back(); }
306
307private:
308 /// The set of attributes that will be applied to the next pushed loop.
309 LoopAttributes StagedAttrs;
310 /// Stack of active loops.
311 llvm::SmallVector<std::unique_ptr<LoopInfo>, 4> Active;
312};
313
314} // end namespace CodeGen
315} // end namespace clang
316
317#endif
318