xref: /llvm-project/clang/lib/CodeGen/CGLoopInfo.cpp (revision 535efab2e533f98a96df31b116b5861b5e29d32d) 
1 //===---- CGLoopInfo.cpp - 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 #include "CGLoopInfo.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/AST/Attr.h"
12 #include "llvm/IR/BasicBlock.h"
13 #include "llvm/IR/CFG.h"
14 #include "llvm/IR/Constants.h"
15 #include "llvm/IR/InstrTypes.h"
16 #include "llvm/IR/Instructions.h"
17 #include "llvm/IR/Metadata.h"
18 using namespace clang::CodeGen;
19 using namespace llvm;
20 
21 MDNode *
22 LoopInfo::createLoopPropertiesMetadata(ArrayRef<Metadata *> LoopProperties) {
23   LLVMContext &Ctx = Header->getContext();
24   SmallVector<Metadata *, 4> NewLoopProperties;
25   TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
26   NewLoopProperties.push_back(TempNode.get());
27   NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
28 
29   MDNode *LoopID = MDNode::getDistinct(Ctx, NewLoopProperties);
30   LoopID->replaceOperandWith(0, LoopID);
31   return LoopID;
32 }
33 
34 MDNode *LoopInfo::createPipeliningMetadata(const LoopAttributes &Attrs,
35                                            ArrayRef<Metadata *> LoopProperties,
36                                            bool &HasUserTransforms) {
37   LLVMContext &Ctx = Header->getContext();
38 
39   Optional<bool> Enabled;
40   if (Attrs.PipelineDisabled)
41     Enabled = false;
42   else if (Attrs.PipelineInitiationInterval != 0)
43     Enabled = true;
44 
45   if (Enabled != true) {
46     SmallVector<Metadata *, 4> NewLoopProperties;
47     if (Enabled == false) {
48       NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
49       NewLoopProperties.push_back(
50           MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.pipeline.disable"),
51                             ConstantAsMetadata::get(ConstantInt::get(
52                                 llvm::Type::getInt1Ty(Ctx), 1))}));
53       LoopProperties = NewLoopProperties;
54     }
55     return createLoopPropertiesMetadata(LoopProperties);
56   }
57 
58   SmallVector<Metadata *, 4> Args;
59   TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
60   Args.push_back(TempNode.get());
61   Args.append(LoopProperties.begin(), LoopProperties.end());
62 
63   if (Attrs.PipelineInitiationInterval > 0) {
64     Metadata *Vals[] = {
65         MDString::get(Ctx, "llvm.loop.pipeline.initiationinterval"),
66         ConstantAsMetadata::get(ConstantInt::get(
67             llvm::Type::getInt32Ty(Ctx), Attrs.PipelineInitiationInterval))};
68     Args.push_back(MDNode::get(Ctx, Vals));
69   }
70 
71   // No follow-up: This is the last transformation.
72 
73   MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
74   LoopID->replaceOperandWith(0, LoopID);
75   HasUserTransforms = true;
76   return LoopID;
77 }
78 
79 MDNode *
80 LoopInfo::createPartialUnrollMetadata(const LoopAttributes &Attrs,
81                                       ArrayRef<Metadata *> LoopProperties,
82                                       bool &HasUserTransforms) {
83   LLVMContext &Ctx = Header->getContext();
84 
85   Optional<bool> Enabled;
86   if (Attrs.UnrollEnable == LoopAttributes::Disable)
87     Enabled = false;
88   else if (Attrs.UnrollEnable == LoopAttributes::Full)
89     Enabled = None;
90   else if (Attrs.UnrollEnable != LoopAttributes::Unspecified ||
91            Attrs.UnrollCount != 0)
92     Enabled = true;
93 
94   if (Enabled != true) {
95     // createFullUnrollMetadata will already have added llvm.loop.unroll.disable
96     // if unrolling is disabled.
97     return createPipeliningMetadata(Attrs, LoopProperties, HasUserTransforms);
98   }
99 
100   SmallVector<Metadata *, 4> FollowupLoopProperties;
101 
102   // Apply all loop properties to the unrolled loop.
103   FollowupLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
104 
105   // Don't unroll an already unrolled loop.
106   FollowupLoopProperties.push_back(
107       MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.disable")));
108 
109   bool FollowupHasTransforms = false;
110   MDNode *Followup = createPipeliningMetadata(Attrs, FollowupLoopProperties,
111                                               FollowupHasTransforms);
112 
113   SmallVector<Metadata *, 4> Args;
114   TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
115   Args.push_back(TempNode.get());
116   Args.append(LoopProperties.begin(), LoopProperties.end());
117 
118   // Setting unroll.count
119   if (Attrs.UnrollCount > 0) {
120     Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.unroll.count"),
121                         ConstantAsMetadata::get(ConstantInt::get(
122                             llvm::Type::getInt32Ty(Ctx), Attrs.UnrollCount))};
123     Args.push_back(MDNode::get(Ctx, Vals));
124   }
125 
126   // Setting unroll.full or unroll.disable
127   if (Attrs.UnrollEnable == LoopAttributes::Enable) {
128     Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.unroll.enable")};
129     Args.push_back(MDNode::get(Ctx, Vals));
130   }
131 
132   if (FollowupHasTransforms)
133     Args.push_back(MDNode::get(
134         Ctx, {MDString::get(Ctx, "llvm.loop.unroll.followup_all"), Followup}));
135 
136   MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
137   LoopID->replaceOperandWith(0, LoopID);
138   HasUserTransforms = true;
139   return LoopID;
140 }
141 
142 MDNode *
143 LoopInfo::createUnrollAndJamMetadata(const LoopAttributes &Attrs,
144                                      ArrayRef<Metadata *> LoopProperties,
145                                      bool &HasUserTransforms) {
146   LLVMContext &Ctx = Header->getContext();
147 
148   Optional<bool> Enabled;
149   if (Attrs.UnrollAndJamEnable == LoopAttributes::Disable)
150     Enabled = false;
151   else if (Attrs.UnrollAndJamEnable == LoopAttributes::Enable ||
152            Attrs.UnrollAndJamCount != 0)
153     Enabled = true;
154 
155   if (Enabled != true) {
156     SmallVector<Metadata *, 4> NewLoopProperties;
157     if (Enabled == false) {
158       NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
159       NewLoopProperties.push_back(MDNode::get(
160           Ctx, MDString::get(Ctx, "llvm.loop.unroll_and_jam.disable")));
161       LoopProperties = NewLoopProperties;
162     }
163     return createPartialUnrollMetadata(Attrs, LoopProperties,
164                                        HasUserTransforms);
165   }
166 
167   SmallVector<Metadata *, 4> FollowupLoopProperties;
168   FollowupLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
169   FollowupLoopProperties.push_back(
170       MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll_and_jam.disable")));
171 
172   bool FollowupHasTransforms = false;
173   MDNode *Followup = createPartialUnrollMetadata(Attrs, FollowupLoopProperties,
174                                                  FollowupHasTransforms);
175 
176   SmallVector<Metadata *, 4> Args;
177   TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
178   Args.push_back(TempNode.get());
179   Args.append(LoopProperties.begin(), LoopProperties.end());
180 
181   // Setting unroll_and_jam.count
182   if (Attrs.UnrollAndJamCount > 0) {
183     Metadata *Vals[] = {
184         MDString::get(Ctx, "llvm.loop.unroll_and_jam.count"),
185         ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt32Ty(Ctx),
186                                                  Attrs.UnrollAndJamCount))};
187     Args.push_back(MDNode::get(Ctx, Vals));
188   }
189 
190   if (Attrs.UnrollAndJamEnable == LoopAttributes::Enable) {
191     Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.unroll_and_jam.enable")};
192     Args.push_back(MDNode::get(Ctx, Vals));
193   }
194 
195   if (FollowupHasTransforms)
196     Args.push_back(MDNode::get(
197         Ctx, {MDString::get(Ctx, "llvm.loop.unroll_and_jam.followup_outer"),
198               Followup}));
199 
200   if (UnrollAndJamInnerFollowup)
201     Args.push_back(MDNode::get(
202         Ctx, {MDString::get(Ctx, "llvm.loop.unroll_and_jam.followup_inner"),
203               UnrollAndJamInnerFollowup}));
204 
205   MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
206   LoopID->replaceOperandWith(0, LoopID);
207   HasUserTransforms = true;
208   return LoopID;
209 }
210 
211 MDNode *
212 LoopInfo::createLoopVectorizeMetadata(const LoopAttributes &Attrs,
213                                       ArrayRef<Metadata *> LoopProperties,
214                                       bool &HasUserTransforms) {
215   LLVMContext &Ctx = Header->getContext();
216 
217   Optional<bool> Enabled;
218   if (Attrs.VectorizeEnable == LoopAttributes::Disable)
219     Enabled = false;
220   else if (Attrs.VectorizeEnable != LoopAttributes::Unspecified ||
221            Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified ||
222            Attrs.InterleaveCount != 0 || Attrs.VectorizeWidth != 0)
223     Enabled = true;
224 
225   if (Enabled != true) {
226     SmallVector<Metadata *, 4> NewLoopProperties;
227     if (Enabled == false) {
228       NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
229       NewLoopProperties.push_back(
230           MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.vectorize.enable"),
231                             ConstantAsMetadata::get(ConstantInt::get(
232                                 llvm::Type::getInt1Ty(Ctx), 0))}));
233       LoopProperties = NewLoopProperties;
234     }
235     return createUnrollAndJamMetadata(Attrs, LoopProperties, HasUserTransforms);
236   }
237 
238   // Apply all loop properties to the vectorized loop.
239   SmallVector<Metadata *, 4> FollowupLoopProperties;
240   FollowupLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
241 
242   // Don't vectorize an already vectorized loop.
243   FollowupLoopProperties.push_back(
244       MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.isvectorized")));
245 
246   bool FollowupHasTransforms = false;
247   MDNode *Followup = createUnrollAndJamMetadata(Attrs, FollowupLoopProperties,
248                                                 FollowupHasTransforms);
249 
250   SmallVector<Metadata *, 4> Args;
251   TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
252   Args.push_back(TempNode.get());
253   Args.append(LoopProperties.begin(), LoopProperties.end());
254 
255   // Setting vectorize.predicate
256   bool IsVectorPredicateEnabled = false;
257   if (Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified &&
258       Attrs.VectorizeEnable != LoopAttributes::Disable &&
259       Attrs.VectorizeWidth < 1) {
260 
261     IsVectorPredicateEnabled =
262         (Attrs.VectorizePredicateEnable == LoopAttributes::Enable);
263 
264     Metadata *Vals[] = {
265         MDString::get(Ctx, "llvm.loop.vectorize.predicate.enable"),
266         ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt1Ty(Ctx),
267                                                  IsVectorPredicateEnabled))};
268     Args.push_back(MDNode::get(Ctx, Vals));
269   }
270 
271   // Setting vectorize.width
272   if (Attrs.VectorizeWidth > 0) {
273     Metadata *Vals[] = {
274         MDString::get(Ctx, "llvm.loop.vectorize.width"),
275         ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt32Ty(Ctx),
276                                                  Attrs.VectorizeWidth))};
277     Args.push_back(MDNode::get(Ctx, Vals));
278   }
279 
280   // Setting interleave.count
281   if (Attrs.InterleaveCount > 0) {
282     Metadata *Vals[] = {
283         MDString::get(Ctx, "llvm.loop.interleave.count"),
284         ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt32Ty(Ctx),
285                                                  Attrs.InterleaveCount))};
286     Args.push_back(MDNode::get(Ctx, Vals));
287   }
288 
289   // Setting vectorize.enable
290   if (Attrs.VectorizeEnable != LoopAttributes::Unspecified ||
291       IsVectorPredicateEnabled) {
292     Metadata *Vals[] = {
293         MDString::get(Ctx, "llvm.loop.vectorize.enable"),
294         ConstantAsMetadata::get(ConstantInt::get(
295             llvm::Type::getInt1Ty(Ctx),
296             IsVectorPredicateEnabled
297                 ? true
298                 : (Attrs.VectorizeEnable == LoopAttributes::Enable)))};
299     Args.push_back(MDNode::get(Ctx, Vals));
300   }
301 
302   if (FollowupHasTransforms)
303     Args.push_back(MDNode::get(
304         Ctx,
305         {MDString::get(Ctx, "llvm.loop.vectorize.followup_all"), Followup}));
306 
307   MDNode *LoopID = MDNode::get(Ctx, Args);
308   LoopID->replaceOperandWith(0, LoopID);
309   HasUserTransforms = true;
310   return LoopID;
311 }
312 
313 MDNode *
314 LoopInfo::createLoopDistributeMetadata(const LoopAttributes &Attrs,
315                                        ArrayRef<Metadata *> LoopProperties,
316                                        bool &HasUserTransforms) {
317   LLVMContext &Ctx = Header->getContext();
318 
319   Optional<bool> Enabled;
320   if (Attrs.DistributeEnable == LoopAttributes::Disable)
321     Enabled = false;
322   if (Attrs.DistributeEnable == LoopAttributes::Enable)
323     Enabled = true;
324 
325   if (Enabled != true) {
326     SmallVector<Metadata *, 4> NewLoopProperties;
327     if (Enabled == false) {
328       NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
329       NewLoopProperties.push_back(
330           MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.distribute.enable"),
331                             ConstantAsMetadata::get(ConstantInt::get(
332                                 llvm::Type::getInt1Ty(Ctx), 0))}));
333       LoopProperties = NewLoopProperties;
334     }
335     return createLoopVectorizeMetadata(Attrs, LoopProperties,
336                                        HasUserTransforms);
337   }
338 
339   bool FollowupHasTransforms = false;
340   MDNode *Followup =
341       createLoopVectorizeMetadata(Attrs, LoopProperties, FollowupHasTransforms);
342 
343   SmallVector<Metadata *, 4> Args;
344   TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
345   Args.push_back(TempNode.get());
346   Args.append(LoopProperties.begin(), LoopProperties.end());
347 
348   Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.distribute.enable"),
349                       ConstantAsMetadata::get(ConstantInt::get(
350                           llvm::Type::getInt1Ty(Ctx),
351                           (Attrs.DistributeEnable == LoopAttributes::Enable)))};
352   Args.push_back(MDNode::get(Ctx, Vals));
353 
354   if (FollowupHasTransforms)
355     Args.push_back(MDNode::get(
356         Ctx,
357         {MDString::get(Ctx, "llvm.loop.distribute.followup_all"), Followup}));
358 
359   MDNode *LoopID = MDNode::get(Ctx, Args);
360   LoopID->replaceOperandWith(0, LoopID);
361   HasUserTransforms = true;
362   return LoopID;
363 }
364 
365 MDNode *LoopInfo::createFullUnrollMetadata(const LoopAttributes &Attrs,
366                                            ArrayRef<Metadata *> LoopProperties,
367                                            bool &HasUserTransforms) {
368   LLVMContext &Ctx = Header->getContext();
369 
370   Optional<bool> Enabled;
371   if (Attrs.UnrollEnable == LoopAttributes::Disable)
372     Enabled = false;
373   else if (Attrs.UnrollEnable == LoopAttributes::Full)
374     Enabled = true;
375 
376   if (Enabled != true) {
377     SmallVector<Metadata *, 4> NewLoopProperties;
378     if (Enabled == false) {
379       NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
380       NewLoopProperties.push_back(
381           MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.disable")));
382       LoopProperties = NewLoopProperties;
383     }
384     return createLoopDistributeMetadata(Attrs, LoopProperties,
385                                         HasUserTransforms);
386   }
387 
388   SmallVector<Metadata *, 4> Args;
389   TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
390   Args.push_back(TempNode.get());
391   Args.append(LoopProperties.begin(), LoopProperties.end());
392   Args.push_back(MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.full")));
393 
394   // No follow-up: there is no loop after full unrolling.
395   // TODO: Warn if there are transformations after full unrolling.
396 
397   MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
398   LoopID->replaceOperandWith(0, LoopID);
399   HasUserTransforms = true;
400   return LoopID;
401 }
402 
403 MDNode *LoopInfo::createMetadata(
404     const LoopAttributes &Attrs,
405     llvm::ArrayRef<llvm::Metadata *> AdditionalLoopProperties,
406     bool &HasUserTransforms) {
407   SmallVector<Metadata *, 3> LoopProperties;
408 
409   // If we have a valid start debug location for the loop, add it.
410   if (StartLoc) {
411     LoopProperties.push_back(StartLoc.getAsMDNode());
412 
413     // If we also have a valid end debug location for the loop, add it.
414     if (EndLoc)
415       LoopProperties.push_back(EndLoc.getAsMDNode());
416   }
417 
418   assert(!!AccGroup == Attrs.IsParallel &&
419          "There must be an access group iff the loop is parallel");
420   if (Attrs.IsParallel) {
421     LLVMContext &Ctx = Header->getContext();
422     LoopProperties.push_back(MDNode::get(
423         Ctx, {MDString::get(Ctx, "llvm.loop.parallel_accesses"), AccGroup}));
424   }
425 
426   LoopProperties.insert(LoopProperties.end(), AdditionalLoopProperties.begin(),
427                         AdditionalLoopProperties.end());
428   return createFullUnrollMetadata(Attrs, LoopProperties, HasUserTransforms);
429 }
430 
431 LoopAttributes::LoopAttributes(bool IsParallel)
432     : IsParallel(IsParallel), VectorizeEnable(LoopAttributes::Unspecified),
433       UnrollEnable(LoopAttributes::Unspecified),
434       UnrollAndJamEnable(LoopAttributes::Unspecified),
435       VectorizePredicateEnable(LoopAttributes::Unspecified), VectorizeWidth(0),
436       InterleaveCount(0), UnrollCount(0), UnrollAndJamCount(0),
437       DistributeEnable(LoopAttributes::Unspecified), PipelineDisabled(false),
438       PipelineInitiationInterval(0) {}
439 
440 void LoopAttributes::clear() {
441   IsParallel = false;
442   VectorizeWidth = 0;
443   InterleaveCount = 0;
444   UnrollCount = 0;
445   UnrollAndJamCount = 0;
446   VectorizeEnable = LoopAttributes::Unspecified;
447   UnrollEnable = LoopAttributes::Unspecified;
448   UnrollAndJamEnable = LoopAttributes::Unspecified;
449   VectorizePredicateEnable = LoopAttributes::Unspecified;
450   DistributeEnable = LoopAttributes::Unspecified;
451   PipelineDisabled = false;
452   PipelineInitiationInterval = 0;
453 }
454 
455 LoopInfo::LoopInfo(BasicBlock *Header, const LoopAttributes &Attrs,
456                    const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc,
457                    LoopInfo *Parent)
458     : Header(Header), Attrs(Attrs), StartLoc(StartLoc), EndLoc(EndLoc),
459       Parent(Parent) {
460 
461   if (Attrs.IsParallel) {
462     // Create an access group for this loop.
463     LLVMContext &Ctx = Header->getContext();
464     AccGroup = MDNode::getDistinct(Ctx, {});
465   }
466 
467   if (!Attrs.IsParallel && Attrs.VectorizeWidth == 0 &&
468       Attrs.InterleaveCount == 0 && Attrs.UnrollCount == 0 &&
469       Attrs.UnrollAndJamCount == 0 && !Attrs.PipelineDisabled &&
470       Attrs.PipelineInitiationInterval == 0 &&
471       Attrs.VectorizePredicateEnable == LoopAttributes::Unspecified &&
472       Attrs.VectorizeEnable == LoopAttributes::Unspecified &&
473       Attrs.UnrollEnable == LoopAttributes::Unspecified &&
474       Attrs.UnrollAndJamEnable == LoopAttributes::Unspecified &&
475       Attrs.DistributeEnable == LoopAttributes::Unspecified && !StartLoc &&
476       !EndLoc)
477     return;
478 
479   TempLoopID = MDNode::getTemporary(Header->getContext(), None);
480 }
481 
482 void LoopInfo::finish() {
483   // We did not annotate the loop body instructions because there are no
484   // attributes for this loop.
485   if (!TempLoopID)
486     return;
487 
488   MDNode *LoopID;
489   LoopAttributes CurLoopAttr = Attrs;
490   LLVMContext &Ctx = Header->getContext();
491 
492   if (Parent && (Parent->Attrs.UnrollAndJamEnable ||
493                  Parent->Attrs.UnrollAndJamCount != 0)) {
494     // Parent unroll-and-jams this loop.
495     // Split the transformations in those that happens before the unroll-and-jam
496     // and those after.
497 
498     LoopAttributes BeforeJam, AfterJam;
499 
500     BeforeJam.IsParallel = AfterJam.IsParallel = Attrs.IsParallel;
501 
502     BeforeJam.VectorizeWidth = Attrs.VectorizeWidth;
503     BeforeJam.InterleaveCount = Attrs.InterleaveCount;
504     BeforeJam.VectorizeEnable = Attrs.VectorizeEnable;
505     BeforeJam.DistributeEnable = Attrs.DistributeEnable;
506     BeforeJam.VectorizePredicateEnable = Attrs.VectorizePredicateEnable;
507 
508     switch (Attrs.UnrollEnable) {
509     case LoopAttributes::Unspecified:
510     case LoopAttributes::Disable:
511       BeforeJam.UnrollEnable = Attrs.UnrollEnable;
512       AfterJam.UnrollEnable = Attrs.UnrollEnable;
513       break;
514     case LoopAttributes::Full:
515       BeforeJam.UnrollEnable = LoopAttributes::Full;
516       break;
517     case LoopAttributes::Enable:
518       AfterJam.UnrollEnable = LoopAttributes::Enable;
519       break;
520     }
521 
522     AfterJam.VectorizePredicateEnable = Attrs.VectorizePredicateEnable;
523     AfterJam.UnrollCount = Attrs.UnrollCount;
524     AfterJam.PipelineDisabled = Attrs.PipelineDisabled;
525     AfterJam.PipelineInitiationInterval = Attrs.PipelineInitiationInterval;
526 
527     // If this loop is subject of an unroll-and-jam by the parent loop, and has
528     // an unroll-and-jam annotation itself, we have to decide whether to first
529     // apply the parent's unroll-and-jam or this loop's unroll-and-jam. The
530     // UnrollAndJam pass processes loops from inner to outer, so we apply the
531     // inner first.
532     BeforeJam.UnrollAndJamCount = Attrs.UnrollAndJamCount;
533     BeforeJam.UnrollAndJamEnable = Attrs.UnrollAndJamEnable;
534 
535     // Set the inner followup metadata to process by the outer loop. Only
536     // consider the first inner loop.
537     if (!Parent->UnrollAndJamInnerFollowup) {
538       // Splitting the attributes into a BeforeJam and an AfterJam part will
539       // stop 'llvm.loop.isvectorized' (generated by vectorization in BeforeJam)
540       // to be forwarded to the AfterJam part. We detect the situation here and
541       // add it manually.
542       SmallVector<Metadata *, 1> BeforeLoopProperties;
543       if (BeforeJam.VectorizeEnable != LoopAttributes::Unspecified ||
544           BeforeJam.VectorizePredicateEnable != LoopAttributes::Unspecified ||
545           BeforeJam.InterleaveCount != 0 || BeforeJam.VectorizeWidth != 0)
546         BeforeLoopProperties.push_back(
547             MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.isvectorized")));
548 
549       bool InnerFollowupHasTransform = false;
550       MDNode *InnerFollowup = createMetadata(AfterJam, BeforeLoopProperties,
551                                              InnerFollowupHasTransform);
552       if (InnerFollowupHasTransform)
553         Parent->UnrollAndJamInnerFollowup = InnerFollowup;
554     }
555 
556     CurLoopAttr = BeforeJam;
557   }
558 
559   bool HasUserTransforms = false;
560   LoopID = createMetadata(CurLoopAttr, {}, HasUserTransforms);
561   TempLoopID->replaceAllUsesWith(LoopID);
562 }
563 
564 void LoopInfoStack::push(BasicBlock *Header, const llvm::DebugLoc &StartLoc,
565                          const llvm::DebugLoc &EndLoc) {
566   Active.push_back(LoopInfo(Header, StagedAttrs, StartLoc, EndLoc,
567                             Active.empty() ? nullptr : &Active.back()));
568   // Clear the attributes so nested loops do not inherit them.
569   StagedAttrs.clear();
570 }
571 
572 void LoopInfoStack::push(BasicBlock *Header, clang::ASTContext &Ctx,
573                          ArrayRef<const clang::Attr *> Attrs,
574                          const llvm::DebugLoc &StartLoc,
575                          const llvm::DebugLoc &EndLoc) {
576 
577   // Identify loop hint attributes from Attrs.
578   for (const auto *Attr : Attrs) {
579     const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(Attr);
580     const OpenCLUnrollHintAttr *OpenCLHint =
581         dyn_cast<OpenCLUnrollHintAttr>(Attr);
582 
583     // Skip non loop hint attributes
584     if (!LH && !OpenCLHint) {
585       continue;
586     }
587 
588     LoopHintAttr::OptionType Option = LoopHintAttr::Unroll;
589     LoopHintAttr::LoopHintState State = LoopHintAttr::Disable;
590     unsigned ValueInt = 1;
591     // Translate opencl_unroll_hint attribute argument to
592     // equivalent LoopHintAttr enums.
593     // OpenCL v2.0 s6.11.5:
594     // 0 - enable unroll (no argument).
595     // 1 - disable unroll.
596     // other positive integer n - unroll by n.
597     if (OpenCLHint) {
598       ValueInt = OpenCLHint->getUnrollHint();
599       if (ValueInt == 0) {
600         State = LoopHintAttr::Enable;
601       } else if (ValueInt != 1) {
602         Option = LoopHintAttr::UnrollCount;
603         State = LoopHintAttr::Numeric;
604       }
605     } else if (LH) {
606       auto *ValueExpr = LH->getValue();
607       if (ValueExpr) {
608         llvm::APSInt ValueAPS = ValueExpr->EvaluateKnownConstInt(Ctx);
609         ValueInt = ValueAPS.getSExtValue();
610       }
611 
612       Option = LH->getOption();
613       State = LH->getState();
614     }
615     switch (State) {
616     case LoopHintAttr::Disable:
617       switch (Option) {
618       case LoopHintAttr::Vectorize:
619         // Disable vectorization by specifying a width of 1.
620         setVectorizeWidth(1);
621         break;
622       case LoopHintAttr::Interleave:
623         // Disable interleaving by speciyfing a count of 1.
624         setInterleaveCount(1);
625         break;
626       case LoopHintAttr::Unroll:
627         setUnrollState(LoopAttributes::Disable);
628         break;
629       case LoopHintAttr::UnrollAndJam:
630         setUnrollAndJamState(LoopAttributes::Disable);
631         break;
632       case LoopHintAttr::VectorizePredicate:
633         setVectorizePredicateState(LoopAttributes::Disable);
634         break;
635       case LoopHintAttr::Distribute:
636         setDistributeState(false);
637         break;
638       case LoopHintAttr::PipelineDisabled:
639         setPipelineDisabled(true);
640         break;
641       case LoopHintAttr::UnrollCount:
642       case LoopHintAttr::UnrollAndJamCount:
643       case LoopHintAttr::VectorizeWidth:
644       case LoopHintAttr::InterleaveCount:
645       case LoopHintAttr::PipelineInitiationInterval:
646         llvm_unreachable("Options cannot be disabled.");
647         break;
648       }
649       break;
650     case LoopHintAttr::Enable:
651       switch (Option) {
652       case LoopHintAttr::Vectorize:
653       case LoopHintAttr::Interleave:
654         setVectorizeEnable(true);
655         break;
656       case LoopHintAttr::Unroll:
657         setUnrollState(LoopAttributes::Enable);
658         break;
659       case LoopHintAttr::UnrollAndJam:
660         setUnrollAndJamState(LoopAttributes::Enable);
661         break;
662       case LoopHintAttr::VectorizePredicate:
663         setVectorizePredicateState(LoopAttributes::Enable);
664         break;
665       case LoopHintAttr::Distribute:
666         setDistributeState(true);
667         break;
668       case LoopHintAttr::UnrollCount:
669       case LoopHintAttr::UnrollAndJamCount:
670       case LoopHintAttr::VectorizeWidth:
671       case LoopHintAttr::InterleaveCount:
672       case LoopHintAttr::PipelineDisabled:
673       case LoopHintAttr::PipelineInitiationInterval:
674         llvm_unreachable("Options cannot enabled.");
675         break;
676       }
677       break;
678     case LoopHintAttr::AssumeSafety:
679       switch (Option) {
680       case LoopHintAttr::Vectorize:
681       case LoopHintAttr::Interleave:
682         // Apply "llvm.mem.parallel_loop_access" metadata to load/stores.
683         setParallel(true);
684         setVectorizeEnable(true);
685         break;
686       case LoopHintAttr::Unroll:
687       case LoopHintAttr::UnrollAndJam:
688       case LoopHintAttr::VectorizePredicate:
689       case LoopHintAttr::UnrollCount:
690       case LoopHintAttr::UnrollAndJamCount:
691       case LoopHintAttr::VectorizeWidth:
692       case LoopHintAttr::InterleaveCount:
693       case LoopHintAttr::Distribute:
694       case LoopHintAttr::PipelineDisabled:
695       case LoopHintAttr::PipelineInitiationInterval:
696         llvm_unreachable("Options cannot be used to assume mem safety.");
697         break;
698       }
699       break;
700     case LoopHintAttr::Full:
701       switch (Option) {
702       case LoopHintAttr::Unroll:
703         setUnrollState(LoopAttributes::Full);
704         break;
705       case LoopHintAttr::UnrollAndJam:
706         setUnrollAndJamState(LoopAttributes::Full);
707         break;
708       case LoopHintAttr::Vectorize:
709       case LoopHintAttr::Interleave:
710       case LoopHintAttr::UnrollCount:
711       case LoopHintAttr::UnrollAndJamCount:
712       case LoopHintAttr::VectorizeWidth:
713       case LoopHintAttr::InterleaveCount:
714       case LoopHintAttr::Distribute:
715       case LoopHintAttr::PipelineDisabled:
716       case LoopHintAttr::PipelineInitiationInterval:
717       case LoopHintAttr::VectorizePredicate:
718         llvm_unreachable("Options cannot be used with 'full' hint.");
719         break;
720       }
721       break;
722     case LoopHintAttr::Numeric:
723       switch (Option) {
724       case LoopHintAttr::VectorizeWidth:
725         setVectorizeWidth(ValueInt);
726         break;
727       case LoopHintAttr::InterleaveCount:
728         setInterleaveCount(ValueInt);
729         break;
730       case LoopHintAttr::UnrollCount:
731         setUnrollCount(ValueInt);
732         break;
733       case LoopHintAttr::UnrollAndJamCount:
734         setUnrollAndJamCount(ValueInt);
735         break;
736       case LoopHintAttr::PipelineInitiationInterval:
737         setPipelineInitiationInterval(ValueInt);
738         break;
739       case LoopHintAttr::Unroll:
740       case LoopHintAttr::UnrollAndJam:
741       case LoopHintAttr::VectorizePredicate:
742       case LoopHintAttr::Vectorize:
743       case LoopHintAttr::Interleave:
744       case LoopHintAttr::Distribute:
745       case LoopHintAttr::PipelineDisabled:
746         llvm_unreachable("Options cannot be assigned a value.");
747         break;
748       }
749       break;
750     }
751   }
752 
753   /// Stage the attributes.
754   push(Header, StartLoc, EndLoc);
755 }
756 
757 void LoopInfoStack::pop() {
758   assert(!Active.empty() && "No active loops to pop");
759   Active.back().finish();
760   Active.pop_back();
761 }
762 
763 void LoopInfoStack::InsertHelper(Instruction *I) const {
764   if (I->mayReadOrWriteMemory()) {
765     SmallVector<Metadata *, 4> AccessGroups;
766     for (const LoopInfo &AL : Active) {
767       // Here we assume that every loop that has an access group is parallel.
768       if (MDNode *Group = AL.getAccessGroup())
769         AccessGroups.push_back(Group);
770     }
771     MDNode *UnionMD = nullptr;
772     if (AccessGroups.size() == 1)
773       UnionMD = cast<MDNode>(AccessGroups[0]);
774     else if (AccessGroups.size() >= 2)
775       UnionMD = MDNode::get(I->getContext(), AccessGroups);
776     I->setMetadata("llvm.access.group", UnionMD);
777   }
778 
779   if (!hasInfo())
780     return;
781 
782   const LoopInfo &L = getInfo();
783   if (!L.getLoopID())
784     return;
785 
786   if (I->isTerminator()) {
787     for (BasicBlock *Succ : successors(I))
788       if (Succ == L.getHeader()) {
789         I->setMetadata(llvm::LLVMContext::MD_loop, L.getLoopID());
790         break;
791       }
792     return;
793   }
794 }
795