xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/CGLoopInfo.cpp (revision 6f63e88c0166ed3e5f2805a9e667c7d24d304cf1) 
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   // vectorize.enable is set if:
290   // 1) loop hint vectorize.enable is set, or
291   // 2) it is implied when vectorize.predicate is set, or
292   // 3) it is implied when vectorize.width is set.
293   if (Attrs.VectorizeEnable != LoopAttributes::Unspecified ||
294       IsVectorPredicateEnabled ||
295       Attrs.VectorizeWidth > 1 ) {
296     bool AttrVal = Attrs.VectorizeEnable != LoopAttributes::Disable;
297     Args.push_back(
298         MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.vectorize.enable"),
299                           ConstantAsMetadata::get(ConstantInt::get(
300                               llvm::Type::getInt1Ty(Ctx), AttrVal))}));
301   }
302 
303   if (FollowupHasTransforms)
304     Args.push_back(MDNode::get(
305         Ctx,
306         {MDString::get(Ctx, "llvm.loop.vectorize.followup_all"), Followup}));
307 
308   MDNode *LoopID = MDNode::get(Ctx, Args);
309   LoopID->replaceOperandWith(0, LoopID);
310   HasUserTransforms = true;
311   return LoopID;
312 }
313 
314 MDNode *
315 LoopInfo::createLoopDistributeMetadata(const LoopAttributes &Attrs,
316                                        ArrayRef<Metadata *> LoopProperties,
317                                        bool &HasUserTransforms) {
318   LLVMContext &Ctx = Header->getContext();
319 
320   Optional<bool> Enabled;
321   if (Attrs.DistributeEnable == LoopAttributes::Disable)
322     Enabled = false;
323   if (Attrs.DistributeEnable == LoopAttributes::Enable)
324     Enabled = true;
325 
326   if (Enabled != true) {
327     SmallVector<Metadata *, 4> NewLoopProperties;
328     if (Enabled == false) {
329       NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
330       NewLoopProperties.push_back(
331           MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.distribute.enable"),
332                             ConstantAsMetadata::get(ConstantInt::get(
333                                 llvm::Type::getInt1Ty(Ctx), 0))}));
334       LoopProperties = NewLoopProperties;
335     }
336     return createLoopVectorizeMetadata(Attrs, LoopProperties,
337                                        HasUserTransforms);
338   }
339 
340   bool FollowupHasTransforms = false;
341   MDNode *Followup =
342       createLoopVectorizeMetadata(Attrs, LoopProperties, FollowupHasTransforms);
343 
344   SmallVector<Metadata *, 4> Args;
345   TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
346   Args.push_back(TempNode.get());
347   Args.append(LoopProperties.begin(), LoopProperties.end());
348 
349   Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.distribute.enable"),
350                       ConstantAsMetadata::get(ConstantInt::get(
351                           llvm::Type::getInt1Ty(Ctx),
352                           (Attrs.DistributeEnable == LoopAttributes::Enable)))};
353   Args.push_back(MDNode::get(Ctx, Vals));
354 
355   if (FollowupHasTransforms)
356     Args.push_back(MDNode::get(
357         Ctx,
358         {MDString::get(Ctx, "llvm.loop.distribute.followup_all"), Followup}));
359 
360   MDNode *LoopID = MDNode::get(Ctx, Args);
361   LoopID->replaceOperandWith(0, LoopID);
362   HasUserTransforms = true;
363   return LoopID;
364 }
365 
366 MDNode *LoopInfo::createFullUnrollMetadata(const LoopAttributes &Attrs,
367                                            ArrayRef<Metadata *> LoopProperties,
368                                            bool &HasUserTransforms) {
369   LLVMContext &Ctx = Header->getContext();
370 
371   Optional<bool> Enabled;
372   if (Attrs.UnrollEnable == LoopAttributes::Disable)
373     Enabled = false;
374   else if (Attrs.UnrollEnable == LoopAttributes::Full)
375     Enabled = true;
376 
377   if (Enabled != true) {
378     SmallVector<Metadata *, 4> NewLoopProperties;
379     if (Enabled == false) {
380       NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
381       NewLoopProperties.push_back(
382           MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.disable")));
383       LoopProperties = NewLoopProperties;
384     }
385     return createLoopDistributeMetadata(Attrs, LoopProperties,
386                                         HasUserTransforms);
387   }
388 
389   SmallVector<Metadata *, 4> Args;
390   TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
391   Args.push_back(TempNode.get());
392   Args.append(LoopProperties.begin(), LoopProperties.end());
393   Args.push_back(MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.full")));
394 
395   // No follow-up: there is no loop after full unrolling.
396   // TODO: Warn if there are transformations after full unrolling.
397 
398   MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
399   LoopID->replaceOperandWith(0, LoopID);
400   HasUserTransforms = true;
401   return LoopID;
402 }
403 
404 MDNode *LoopInfo::createMetadata(
405     const LoopAttributes &Attrs,
406     llvm::ArrayRef<llvm::Metadata *> AdditionalLoopProperties,
407     bool &HasUserTransforms) {
408   SmallVector<Metadata *, 3> LoopProperties;
409 
410   // If we have a valid start debug location for the loop, add it.
411   if (StartLoc) {
412     LoopProperties.push_back(StartLoc.getAsMDNode());
413 
414     // If we also have a valid end debug location for the loop, add it.
415     if (EndLoc)
416       LoopProperties.push_back(EndLoc.getAsMDNode());
417   }
418 
419   assert(!!AccGroup == Attrs.IsParallel &&
420          "There must be an access group iff the loop is parallel");
421   if (Attrs.IsParallel) {
422     LLVMContext &Ctx = Header->getContext();
423     LoopProperties.push_back(MDNode::get(
424         Ctx, {MDString::get(Ctx, "llvm.loop.parallel_accesses"), AccGroup}));
425   }
426 
427   LoopProperties.insert(LoopProperties.end(), AdditionalLoopProperties.begin(),
428                         AdditionalLoopProperties.end());
429   return createFullUnrollMetadata(Attrs, LoopProperties, HasUserTransforms);
430 }
431 
432 LoopAttributes::LoopAttributes(bool IsParallel)
433     : IsParallel(IsParallel), VectorizeEnable(LoopAttributes::Unspecified),
434       UnrollEnable(LoopAttributes::Unspecified),
435       UnrollAndJamEnable(LoopAttributes::Unspecified),
436       VectorizePredicateEnable(LoopAttributes::Unspecified), VectorizeWidth(0),
437       InterleaveCount(0), UnrollCount(0), UnrollAndJamCount(0),
438       DistributeEnable(LoopAttributes::Unspecified), PipelineDisabled(false),
439       PipelineInitiationInterval(0) {}
440 
441 void LoopAttributes::clear() {
442   IsParallel = false;
443   VectorizeWidth = 0;
444   InterleaveCount = 0;
445   UnrollCount = 0;
446   UnrollAndJamCount = 0;
447   VectorizeEnable = LoopAttributes::Unspecified;
448   UnrollEnable = LoopAttributes::Unspecified;
449   UnrollAndJamEnable = LoopAttributes::Unspecified;
450   VectorizePredicateEnable = LoopAttributes::Unspecified;
451   DistributeEnable = LoopAttributes::Unspecified;
452   PipelineDisabled = false;
453   PipelineInitiationInterval = 0;
454 }
455 
456 LoopInfo::LoopInfo(BasicBlock *Header, const LoopAttributes &Attrs,
457                    const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc,
458                    LoopInfo *Parent)
459     : Header(Header), Attrs(Attrs), StartLoc(StartLoc), EndLoc(EndLoc),
460       Parent(Parent) {
461 
462   if (Attrs.IsParallel) {
463     // Create an access group for this loop.
464     LLVMContext &Ctx = Header->getContext();
465     AccGroup = MDNode::getDistinct(Ctx, {});
466   }
467 
468   if (!Attrs.IsParallel && Attrs.VectorizeWidth == 0 &&
469       Attrs.InterleaveCount == 0 && Attrs.UnrollCount == 0 &&
470       Attrs.UnrollAndJamCount == 0 && !Attrs.PipelineDisabled &&
471       Attrs.PipelineInitiationInterval == 0 &&
472       Attrs.VectorizePredicateEnable == LoopAttributes::Unspecified &&
473       Attrs.VectorizeEnable == LoopAttributes::Unspecified &&
474       Attrs.UnrollEnable == LoopAttributes::Unspecified &&
475       Attrs.UnrollAndJamEnable == LoopAttributes::Unspecified &&
476       Attrs.DistributeEnable == LoopAttributes::Unspecified && !StartLoc &&
477       !EndLoc)
478     return;
479 
480   TempLoopID = MDNode::getTemporary(Header->getContext(), None);
481 }
482 
483 void LoopInfo::finish() {
484   // We did not annotate the loop body instructions because there are no
485   // attributes for this loop.
486   if (!TempLoopID)
487     return;
488 
489   MDNode *LoopID;
490   LoopAttributes CurLoopAttr = Attrs;
491   LLVMContext &Ctx = Header->getContext();
492 
493   if (Parent && (Parent->Attrs.UnrollAndJamEnable ||
494                  Parent->Attrs.UnrollAndJamCount != 0)) {
495     // Parent unroll-and-jams this loop.
496     // Split the transformations in those that happens before the unroll-and-jam
497     // and those after.
498 
499     LoopAttributes BeforeJam, AfterJam;
500 
501     BeforeJam.IsParallel = AfterJam.IsParallel = Attrs.IsParallel;
502 
503     BeforeJam.VectorizeWidth = Attrs.VectorizeWidth;
504     BeforeJam.InterleaveCount = Attrs.InterleaveCount;
505     BeforeJam.VectorizeEnable = Attrs.VectorizeEnable;
506     BeforeJam.DistributeEnable = Attrs.DistributeEnable;
507     BeforeJam.VectorizePredicateEnable = Attrs.VectorizePredicateEnable;
508 
509     switch (Attrs.UnrollEnable) {
510     case LoopAttributes::Unspecified:
511     case LoopAttributes::Disable:
512       BeforeJam.UnrollEnable = Attrs.UnrollEnable;
513       AfterJam.UnrollEnable = Attrs.UnrollEnable;
514       break;
515     case LoopAttributes::Full:
516       BeforeJam.UnrollEnable = LoopAttributes::Full;
517       break;
518     case LoopAttributes::Enable:
519       AfterJam.UnrollEnable = LoopAttributes::Enable;
520       break;
521     }
522 
523     AfterJam.VectorizePredicateEnable = Attrs.VectorizePredicateEnable;
524     AfterJam.UnrollCount = Attrs.UnrollCount;
525     AfterJam.PipelineDisabled = Attrs.PipelineDisabled;
526     AfterJam.PipelineInitiationInterval = Attrs.PipelineInitiationInterval;
527 
528     // If this loop is subject of an unroll-and-jam by the parent loop, and has
529     // an unroll-and-jam annotation itself, we have to decide whether to first
530     // apply the parent's unroll-and-jam or this loop's unroll-and-jam. The
531     // UnrollAndJam pass processes loops from inner to outer, so we apply the
532     // inner first.
533     BeforeJam.UnrollAndJamCount = Attrs.UnrollAndJamCount;
534     BeforeJam.UnrollAndJamEnable = Attrs.UnrollAndJamEnable;
535 
536     // Set the inner followup metadata to process by the outer loop. Only
537     // consider the first inner loop.
538     if (!Parent->UnrollAndJamInnerFollowup) {
539       // Splitting the attributes into a BeforeJam and an AfterJam part will
540       // stop 'llvm.loop.isvectorized' (generated by vectorization in BeforeJam)
541       // to be forwarded to the AfterJam part. We detect the situation here and
542       // add it manually.
543       SmallVector<Metadata *, 1> BeforeLoopProperties;
544       if (BeforeJam.VectorizeEnable != LoopAttributes::Unspecified ||
545           BeforeJam.VectorizePredicateEnable != LoopAttributes::Unspecified ||
546           BeforeJam.InterleaveCount != 0 || BeforeJam.VectorizeWidth != 0)
547         BeforeLoopProperties.push_back(
548             MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.isvectorized")));
549 
550       bool InnerFollowupHasTransform = false;
551       MDNode *InnerFollowup = createMetadata(AfterJam, BeforeLoopProperties,
552                                              InnerFollowupHasTransform);
553       if (InnerFollowupHasTransform)
554         Parent->UnrollAndJamInnerFollowup = InnerFollowup;
555     }
556 
557     CurLoopAttr = BeforeJam;
558   }
559 
560   bool HasUserTransforms = false;
561   LoopID = createMetadata(CurLoopAttr, {}, HasUserTransforms);
562   TempLoopID->replaceAllUsesWith(LoopID);
563 }
564 
565 void LoopInfoStack::push(BasicBlock *Header, const llvm::DebugLoc &StartLoc,
566                          const llvm::DebugLoc &EndLoc) {
567   Active.emplace_back(
568       new LoopInfo(Header, StagedAttrs, StartLoc, EndLoc,
569                    Active.empty() ? nullptr : Active.back().get()));
570   // Clear the attributes so nested loops do not inherit them.
571   StagedAttrs.clear();
572 }
573 
574 void LoopInfoStack::push(BasicBlock *Header, clang::ASTContext &Ctx,
575                          ArrayRef<const clang::Attr *> Attrs,
576                          const llvm::DebugLoc &StartLoc,
577                          const llvm::DebugLoc &EndLoc) {
578 
579   // Identify loop hint attributes from Attrs.
580   for (const auto *Attr : Attrs) {
581     const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(Attr);
582     const OpenCLUnrollHintAttr *OpenCLHint =
583         dyn_cast<OpenCLUnrollHintAttr>(Attr);
584 
585     // Skip non loop hint attributes
586     if (!LH && !OpenCLHint) {
587       continue;
588     }
589 
590     LoopHintAttr::OptionType Option = LoopHintAttr::Unroll;
591     LoopHintAttr::LoopHintState State = LoopHintAttr::Disable;
592     unsigned ValueInt = 1;
593     // Translate opencl_unroll_hint attribute argument to
594     // equivalent LoopHintAttr enums.
595     // OpenCL v2.0 s6.11.5:
596     // 0 - enable unroll (no argument).
597     // 1 - disable unroll.
598     // other positive integer n - unroll by n.
599     if (OpenCLHint) {
600       ValueInt = OpenCLHint->getUnrollHint();
601       if (ValueInt == 0) {
602         State = LoopHintAttr::Enable;
603       } else if (ValueInt != 1) {
604         Option = LoopHintAttr::UnrollCount;
605         State = LoopHintAttr::Numeric;
606       }
607     } else if (LH) {
608       auto *ValueExpr = LH->getValue();
609       if (ValueExpr) {
610         llvm::APSInt ValueAPS = ValueExpr->EvaluateKnownConstInt(Ctx);
611         ValueInt = ValueAPS.getSExtValue();
612       }
613 
614       Option = LH->getOption();
615       State = LH->getState();
616     }
617     switch (State) {
618     case LoopHintAttr::Disable:
619       switch (Option) {
620       case LoopHintAttr::Vectorize:
621         // Disable vectorization by specifying a width of 1.
622         setVectorizeWidth(1);
623         break;
624       case LoopHintAttr::Interleave:
625         // Disable interleaving by speciyfing a count of 1.
626         setInterleaveCount(1);
627         break;
628       case LoopHintAttr::Unroll:
629         setUnrollState(LoopAttributes::Disable);
630         break;
631       case LoopHintAttr::UnrollAndJam:
632         setUnrollAndJamState(LoopAttributes::Disable);
633         break;
634       case LoopHintAttr::VectorizePredicate:
635         setVectorizePredicateState(LoopAttributes::Disable);
636         break;
637       case LoopHintAttr::Distribute:
638         setDistributeState(false);
639         break;
640       case LoopHintAttr::PipelineDisabled:
641         setPipelineDisabled(true);
642         break;
643       case LoopHintAttr::UnrollCount:
644       case LoopHintAttr::UnrollAndJamCount:
645       case LoopHintAttr::VectorizeWidth:
646       case LoopHintAttr::InterleaveCount:
647       case LoopHintAttr::PipelineInitiationInterval:
648         llvm_unreachable("Options cannot be disabled.");
649         break;
650       }
651       break;
652     case LoopHintAttr::Enable:
653       switch (Option) {
654       case LoopHintAttr::Vectorize:
655       case LoopHintAttr::Interleave:
656         setVectorizeEnable(true);
657         break;
658       case LoopHintAttr::Unroll:
659         setUnrollState(LoopAttributes::Enable);
660         break;
661       case LoopHintAttr::UnrollAndJam:
662         setUnrollAndJamState(LoopAttributes::Enable);
663         break;
664       case LoopHintAttr::VectorizePredicate:
665         setVectorizePredicateState(LoopAttributes::Enable);
666         break;
667       case LoopHintAttr::Distribute:
668         setDistributeState(true);
669         break;
670       case LoopHintAttr::UnrollCount:
671       case LoopHintAttr::UnrollAndJamCount:
672       case LoopHintAttr::VectorizeWidth:
673       case LoopHintAttr::InterleaveCount:
674       case LoopHintAttr::PipelineDisabled:
675       case LoopHintAttr::PipelineInitiationInterval:
676         llvm_unreachable("Options cannot enabled.");
677         break;
678       }
679       break;
680     case LoopHintAttr::AssumeSafety:
681       switch (Option) {
682       case LoopHintAttr::Vectorize:
683       case LoopHintAttr::Interleave:
684         // Apply "llvm.mem.parallel_loop_access" metadata to load/stores.
685         setParallel(true);
686         setVectorizeEnable(true);
687         break;
688       case LoopHintAttr::Unroll:
689       case LoopHintAttr::UnrollAndJam:
690       case LoopHintAttr::VectorizePredicate:
691       case LoopHintAttr::UnrollCount:
692       case LoopHintAttr::UnrollAndJamCount:
693       case LoopHintAttr::VectorizeWidth:
694       case LoopHintAttr::InterleaveCount:
695       case LoopHintAttr::Distribute:
696       case LoopHintAttr::PipelineDisabled:
697       case LoopHintAttr::PipelineInitiationInterval:
698         llvm_unreachable("Options cannot be used to assume mem safety.");
699         break;
700       }
701       break;
702     case LoopHintAttr::Full:
703       switch (Option) {
704       case LoopHintAttr::Unroll:
705         setUnrollState(LoopAttributes::Full);
706         break;
707       case LoopHintAttr::UnrollAndJam:
708         setUnrollAndJamState(LoopAttributes::Full);
709         break;
710       case LoopHintAttr::Vectorize:
711       case LoopHintAttr::Interleave:
712       case LoopHintAttr::UnrollCount:
713       case LoopHintAttr::UnrollAndJamCount:
714       case LoopHintAttr::VectorizeWidth:
715       case LoopHintAttr::InterleaveCount:
716       case LoopHintAttr::Distribute:
717       case LoopHintAttr::PipelineDisabled:
718       case LoopHintAttr::PipelineInitiationInterval:
719       case LoopHintAttr::VectorizePredicate:
720         llvm_unreachable("Options cannot be used with 'full' hint.");
721         break;
722       }
723       break;
724     case LoopHintAttr::Numeric:
725       switch (Option) {
726       case LoopHintAttr::VectorizeWidth:
727         setVectorizeWidth(ValueInt);
728         break;
729       case LoopHintAttr::InterleaveCount:
730         setInterleaveCount(ValueInt);
731         break;
732       case LoopHintAttr::UnrollCount:
733         setUnrollCount(ValueInt);
734         break;
735       case LoopHintAttr::UnrollAndJamCount:
736         setUnrollAndJamCount(ValueInt);
737         break;
738       case LoopHintAttr::PipelineInitiationInterval:
739         setPipelineInitiationInterval(ValueInt);
740         break;
741       case LoopHintAttr::Unroll:
742       case LoopHintAttr::UnrollAndJam:
743       case LoopHintAttr::VectorizePredicate:
744       case LoopHintAttr::Vectorize:
745       case LoopHintAttr::Interleave:
746       case LoopHintAttr::Distribute:
747       case LoopHintAttr::PipelineDisabled:
748         llvm_unreachable("Options cannot be assigned a value.");
749         break;
750       }
751       break;
752     }
753   }
754 
755   /// Stage the attributes.
756   push(Header, StartLoc, EndLoc);
757 }
758 
759 void LoopInfoStack::pop() {
760   assert(!Active.empty() && "No active loops to pop");
761   Active.back()->finish();
762   Active.pop_back();
763 }
764 
765 void LoopInfoStack::InsertHelper(Instruction *I) const {
766   if (I->mayReadOrWriteMemory()) {
767     SmallVector<Metadata *, 4> AccessGroups;
768     for (const auto &AL : Active) {
769       // Here we assume that every loop that has an access group is parallel.
770       if (MDNode *Group = AL->getAccessGroup())
771         AccessGroups.push_back(Group);
772     }
773     MDNode *UnionMD = nullptr;
774     if (AccessGroups.size() == 1)
775       UnionMD = cast<MDNode>(AccessGroups[0]);
776     else if (AccessGroups.size() >= 2)
777       UnionMD = MDNode::get(I->getContext(), AccessGroups);
778     I->setMetadata("llvm.access.group", UnionMD);
779   }
780 
781   if (!hasInfo())
782     return;
783 
784   const LoopInfo &L = getInfo();
785   if (!L.getLoopID())
786     return;
787 
788   if (I->isTerminator()) {
789     for (BasicBlock *Succ : successors(I))
790       if (Succ == L.getHeader()) {
791         I->setMetadata(llvm::LLVMContext::MD_loop, L.getLoopID());
792         break;
793       }
794     return;
795   }
796 }
797