clang/lib/CodeGen/CGLoopInfo.cpp

   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 "clang/AST/Expr.h"
  13 #include "clang/Basic/CodeGenOptions.h"
  14 #include "llvm/IR/BasicBlock.h"
  15 #include "llvm/IR/CFG.h"
  16 #include "llvm/IR/Constants.h"
  17 #include "llvm/IR/InstrTypes.h"
  18 #include "llvm/IR/Instructions.h"
  19 #include "llvm/IR/Metadata.h"
  20 #include <optional>
  21 using namespace clang::CodeGen;
  22 using namespace llvm;
  23
  24 MDNode *
  25 LoopInfo::createLoopPropertiesMetadata(ArrayRef<Metadata *> LoopProperties) {
  26   LLVMContext &Ctx = Header->getContext();
  27   SmallVector<Metadata *, 4> NewLoopProperties;
  28   NewLoopProperties.push_back(nullptr);
  29   NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
  30
  31   MDNode *LoopID = MDNode::getDistinct(Ctx, NewLoopProperties);
  32   LoopID->replaceOperandWith(0, LoopID);
  33   return LoopID;
  34 }
  35
  36 MDNode *LoopInfo::createPipeliningMetadata(const LoopAttributes &Attrs,
  37                                            ArrayRef<Metadata *> LoopProperties,
  38                                            bool &HasUserTransforms) {
  39   LLVMContext &Ctx = Header->getContext();
  40
  41   std::optional<bool> Enabled;
  42   if (Attrs.PipelineDisabled)
  43     Enabled = false;
  44   else if (Attrs.PipelineInitiationInterval != 0)
  45     Enabled = true;
  46
  47   if (Enabled != true) {
  48     SmallVector<Metadata *, 4> NewLoopProperties;
  49     if (Enabled == false) {
  50       NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
  51       NewLoopProperties.push_back(
  52           MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.pipeline.disable"),
  53                             ConstantAsMetadata::get(ConstantInt::get(
  54                                 llvm::Type::getInt1Ty(Ctx), 1))}));
  55       LoopProperties = NewLoopProperties;
  56     }
  57     return createLoopPropertiesMetadata(LoopProperties);
  58   }
  59
  60   SmallVector<Metadata *, 4> Args;
  61   Args.push_back(nullptr);
  62   Args.append(LoopProperties.begin(), LoopProperties.end());
  63
  64   if (Attrs.PipelineInitiationInterval > 0) {
  65     Metadata *Vals[] = {
  66         MDString::get(Ctx, "llvm.loop.pipeline.initiationinterval"),
  67         ConstantAsMetadata::get(ConstantInt::get(
  68             llvm::Type::getInt32Ty(Ctx), Attrs.PipelineInitiationInterval))};
  69     Args.push_back(MDNode::get(Ctx, Vals));
  70   }
  71
  72   // No follow-up: This is the last transformation.
  73
  74   MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
  75   LoopID->replaceOperandWith(0, LoopID);
  76   HasUserTransforms = true;
  77   return LoopID;
  78 }
  79
  80 MDNode *
  81 LoopInfo::createPartialUnrollMetadata(const LoopAttributes &Attrs,
  82                                       ArrayRef<Metadata *> LoopProperties,
  83                                       bool &HasUserTransforms) {
  84   LLVMContext &Ctx = Header->getContext();
  85
  86   std::optional<bool> Enabled;
  87   if (Attrs.UnrollEnable == LoopAttributes::Disable)
  88     Enabled = false;
  89   else if (Attrs.UnrollEnable == LoopAttributes::Full)
  90     Enabled = std::nullopt;
  91   else if (Attrs.UnrollEnable != LoopAttributes::Unspecified ||
  92            Attrs.UnrollCount != 0)
  93     Enabled = true;
  94
  95   if (Enabled != true) {
  96     // createFullUnrollMetadata will already have added llvm.loop.unroll.disable
  97     // if unrolling is disabled.
  98     return createPipeliningMetadata(Attrs, LoopProperties, HasUserTransforms);
  99   }
 100
 101   SmallVector<Metadata *, 4> FollowupLoopProperties;
 102
 103   // Apply all loop properties to the unrolled loop.
 104   FollowupLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
 105
 106   // Don't unroll an already unrolled loop.
 107   FollowupLoopProperties.push_back(
 108       MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.disable")));
 109
 110   bool FollowupHasTransforms = false;
 111   MDNode *Followup = createPipeliningMetadata(Attrs, FollowupLoopProperties,
 112                                               FollowupHasTransforms);
 113
 114   SmallVector<Metadata *, 4> Args;
 115   Args.push_back(nullptr);
 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   std::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   Args.push_back(nullptr);
 178   Args.append(LoopProperties.begin(), LoopProperties.end());
 179
 180   // Setting unroll_and_jam.count
 181   if (Attrs.UnrollAndJamCount > 0) {
 182     Metadata *Vals[] = {
 183         MDString::get(Ctx, "llvm.loop.unroll_and_jam.count"),
 184         ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt32Ty(Ctx),
 185                                                  Attrs.UnrollAndJamCount))};
 186     Args.push_back(MDNode::get(Ctx, Vals));
 187   }
 188
 189   if (Attrs.UnrollAndJamEnable == LoopAttributes::Enable) {
 190     Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.unroll_and_jam.enable")};
 191     Args.push_back(MDNode::get(Ctx, Vals));
 192   }
 193
 194   if (FollowupHasTransforms)
 195     Args.push_back(MDNode::get(
 196         Ctx, {MDString::get(Ctx, "llvm.loop.unroll_and_jam.followup_outer"),
 197               Followup}));
 198
 199   if (UnrollAndJamInnerFollowup)
 200     Args.push_back(MDNode::get(
 201         Ctx, {MDString::get(Ctx, "llvm.loop.unroll_and_jam.followup_inner"),
 202               UnrollAndJamInnerFollowup}));
 203
 204   MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
 205   LoopID->replaceOperandWith(0, LoopID);
 206   HasUserTransforms = true;
 207   return LoopID;
 208 }
 209
 210 MDNode *
 211 LoopInfo::createLoopVectorizeMetadata(const LoopAttributes &Attrs,
 212                                       ArrayRef<Metadata *> LoopProperties,
 213                                       bool &HasUserTransforms) {
 214   LLVMContext &Ctx = Header->getContext();
 215
 216   std::optional<bool> Enabled;
 217   if (Attrs.VectorizeEnable == LoopAttributes::Disable)
 218     Enabled = false;
 219   else if (Attrs.VectorizeEnable != LoopAttributes::Unspecified ||
 220            Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified ||
 221            Attrs.InterleaveCount != 0 || Attrs.VectorizeWidth != 0 ||
 222            Attrs.VectorizeScalable != LoopAttributes::Unspecified)
 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   Args.push_back(nullptr);
 252   Args.append(LoopProperties.begin(), LoopProperties.end());
 253
 254   // Setting vectorize.predicate when it has been specified and vectorization
 255   // has not been disabled.
 256   bool IsVectorPredicateEnabled = false;
 257   if (Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified) {
 258     IsVectorPredicateEnabled =
 259         (Attrs.VectorizePredicateEnable == LoopAttributes::Enable);
 260
 261     Metadata *Vals[] = {
 262         MDString::get(Ctx, "llvm.loop.vectorize.predicate.enable"),
 263         ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt1Ty(Ctx),
 264                                                  IsVectorPredicateEnabled))};
 265     Args.push_back(MDNode::get(Ctx, Vals));
 266   }
 267
 268   // Setting vectorize.width
 269   if (Attrs.VectorizeWidth > 0) {
 270     Metadata *Vals[] = {
 271         MDString::get(Ctx, "llvm.loop.vectorize.width"),
 272         ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt32Ty(Ctx),
 273                                                  Attrs.VectorizeWidth))};
 274
 275     Args.push_back(MDNode::get(Ctx, Vals));
 276   }
 277
 278   if (Attrs.VectorizeScalable != LoopAttributes::Unspecified) {
 279     bool IsScalable = Attrs.VectorizeScalable == LoopAttributes::Enable;
 280     Metadata *Vals[] = {
 281         MDString::get(Ctx, "llvm.loop.vectorize.scalable.enable"),
 282         ConstantAsMetadata::get(
 283             ConstantInt::get(llvm::Type::getInt1Ty(Ctx), IsScalable))};
 284     Args.push_back(MDNode::get(Ctx, Vals));
 285   }
 286
 287   // Setting interleave.count
 288   if (Attrs.InterleaveCount > 0) {
 289     Metadata *Vals[] = {
 290         MDString::get(Ctx, "llvm.loop.interleave.count"),
 291         ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt32Ty(Ctx),
 292                                                  Attrs.InterleaveCount))};
 293     Args.push_back(MDNode::get(Ctx, Vals));
 294   }
 295
 296   // vectorize.enable is set if:
 297   // 1) loop hint vectorize.enable is set, or
 298   // 2) it is implied when vectorize.predicate is set, or
 299   // 3) it is implied when vectorize.width is set to a value > 1
 300   // 4) it is implied when vectorize.scalable.enable is true
 301   // 5) it is implied when vectorize.width is unset (0) and the user
 302   //    explicitly requested fixed-width vectorization, i.e.
 303   //    vectorize.scalable.enable is false.
 304   if (Attrs.VectorizeEnable != LoopAttributes::Unspecified ||
 305       (IsVectorPredicateEnabled && Attrs.VectorizeWidth != 1) ||
 306       Attrs.VectorizeWidth > 1 ||
 307       Attrs.VectorizeScalable == LoopAttributes::Enable ||
 308       (Attrs.VectorizeScalable == LoopAttributes::Disable &&
 309        Attrs.VectorizeWidth != 1)) {
 310     bool AttrVal = Attrs.VectorizeEnable != LoopAttributes::Disable;
 311     Args.push_back(
 312         MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.vectorize.enable"),
 313                           ConstantAsMetadata::get(ConstantInt::get(
 314                               llvm::Type::getInt1Ty(Ctx), AttrVal))}));
 315   }
 316
 317   if (FollowupHasTransforms)
 318     Args.push_back(MDNode::get(
 319         Ctx,
 320         {MDString::get(Ctx, "llvm.loop.vectorize.followup_all"), Followup}));
 321
 322   MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
 323   LoopID->replaceOperandWith(0, LoopID);
 324   HasUserTransforms = true;
 325   return LoopID;
 326 }
 327
 328 MDNode *
 329 LoopInfo::createLoopDistributeMetadata(const LoopAttributes &Attrs,
 330                                        ArrayRef<Metadata *> LoopProperties,
 331                                        bool &HasUserTransforms) {
 332   LLVMContext &Ctx = Header->getContext();
 333
 334   std::optional<bool> Enabled;
 335   if (Attrs.DistributeEnable == LoopAttributes::Disable)
 336     Enabled = false;
 337   if (Attrs.DistributeEnable == LoopAttributes::Enable)
 338     Enabled = true;
 339
 340   if (Enabled != true) {
 341     SmallVector<Metadata *, 4> NewLoopProperties;
 342     if (Enabled == false) {
 343       NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
 344       NewLoopProperties.push_back(
 345           MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.distribute.enable"),
 346                             ConstantAsMetadata::get(ConstantInt::get(
 347                                 llvm::Type::getInt1Ty(Ctx), 0))}));
 348       LoopProperties = NewLoopProperties;
 349     }
 350     return createLoopVectorizeMetadata(Attrs, LoopProperties,
 351                                        HasUserTransforms);
 352   }
 353
 354   bool FollowupHasTransforms = false;
 355   MDNode *Followup =
 356       createLoopVectorizeMetadata(Attrs, LoopProperties, FollowupHasTransforms);
 357
 358   SmallVector<Metadata *, 4> Args;
 359   Args.push_back(nullptr);
 360   Args.append(LoopProperties.begin(), LoopProperties.end());
 361
 362   Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.distribute.enable"),
 363                       ConstantAsMetadata::get(ConstantInt::get(
 364                           llvm::Type::getInt1Ty(Ctx),
 365                           (Attrs.DistributeEnable == LoopAttributes::Enable)))};
 366   Args.push_back(MDNode::get(Ctx, Vals));
 367
 368   if (FollowupHasTransforms)
 369     Args.push_back(MDNode::get(
 370         Ctx,
 371         {MDString::get(Ctx, "llvm.loop.distribute.followup_all"), Followup}));
 372
 373   MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
 374   LoopID->replaceOperandWith(0, LoopID);
 375   HasUserTransforms = true;
 376   return LoopID;
 377 }
 378
 379 MDNode *LoopInfo::createFullUnrollMetadata(const LoopAttributes &Attrs,
 380                                            ArrayRef<Metadata *> LoopProperties,
 381                                            bool &HasUserTransforms) {
 382   LLVMContext &Ctx = Header->getContext();
 383
 384   std::optional<bool> Enabled;
 385   if (Attrs.UnrollEnable == LoopAttributes::Disable)
 386     Enabled = false;
 387   else if (Attrs.UnrollEnable == LoopAttributes::Full)
 388     Enabled = true;
 389
 390   if (Enabled != true) {
 391     SmallVector<Metadata *, 4> NewLoopProperties;
 392     if (Enabled == false) {
 393       NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
 394       NewLoopProperties.push_back(
 395           MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.disable")));
 396       LoopProperties = NewLoopProperties;
 397     }
 398     return createLoopDistributeMetadata(Attrs, LoopProperties,
 399                                         HasUserTransforms);
 400   }
 401
 402   SmallVector<Metadata *, 4> Args;
 403   Args.push_back(nullptr);
 404   Args.append(LoopProperties.begin(), LoopProperties.end());
 405   Args.push_back(MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.full")));
 406
 407   // No follow-up: there is no loop after full unrolling.
 408   // TODO: Warn if there are transformations after full unrolling.
 409
 410   MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
 411   LoopID->replaceOperandWith(0, LoopID);
 412   HasUserTransforms = true;
 413   return LoopID;
 414 }
 415
 416 MDNode *LoopInfo::createMetadata(
 417     const LoopAttributes &Attrs,
 418     llvm::ArrayRef<llvm::Metadata *> AdditionalLoopProperties,
 419     bool &HasUserTransforms) {
 420   SmallVector<Metadata *, 3> LoopProperties;
 421
 422   // If we have a valid start debug location for the loop, add it.
 423   if (StartLoc) {
 424     LoopProperties.push_back(StartLoc.getAsMDNode());
 425
 426     // If we also have a valid end debug location for the loop, add it.
 427     if (EndLoc)
 428       LoopProperties.push_back(EndLoc.getAsMDNode());
 429   }
 430
 431   LLVMContext &Ctx = Header->getContext();
 432   if (Attrs.MustProgress)
 433     LoopProperties.push_back(
 434         MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.mustprogress")));
 435
 436   assert(!!AccGroup == Attrs.IsParallel &&
 437          "There must be an access group iff the loop is parallel");
 438   if (Attrs.IsParallel) {
 439     LoopProperties.push_back(MDNode::get(
 440         Ctx, {MDString::get(Ctx, "llvm.loop.parallel_accesses"), AccGroup}));
 441   }
 442
 443   LoopProperties.insert(LoopProperties.end(), AdditionalLoopProperties.begin(),
 444                         AdditionalLoopProperties.end());
 445   return createFullUnrollMetadata(Attrs, LoopProperties, HasUserTransforms);
 446 }
 447
 448 LoopAttributes::LoopAttributes(bool IsParallel)
 449     : IsParallel(IsParallel), VectorizeEnable(LoopAttributes::Unspecified),
 450       UnrollEnable(LoopAttributes::Unspecified),
 451       UnrollAndJamEnable(LoopAttributes::Unspecified),
 452       VectorizePredicateEnable(LoopAttributes::Unspecified), VectorizeWidth(0),
 453       VectorizeScalable(LoopAttributes::Unspecified), InterleaveCount(0),
 454       UnrollCount(0), UnrollAndJamCount(0),
 455       DistributeEnable(LoopAttributes::Unspecified), PipelineDisabled(false),
 456       PipelineInitiationInterval(0), MustProgress(false) {}
 457
 458 void LoopAttributes::clear() {
 459   IsParallel = false;
 460   VectorizeWidth = 0;
 461   VectorizeScalable = LoopAttributes::Unspecified;
 462   InterleaveCount = 0;
 463   UnrollCount = 0;
 464   UnrollAndJamCount = 0;
 465   VectorizeEnable = LoopAttributes::Unspecified;
 466   UnrollEnable = LoopAttributes::Unspecified;
 467   UnrollAndJamEnable = LoopAttributes::Unspecified;
 468   VectorizePredicateEnable = LoopAttributes::Unspecified;
 469   DistributeEnable = LoopAttributes::Unspecified;
 470   PipelineDisabled = false;
 471   PipelineInitiationInterval = 0;
 472   MustProgress = false;
 473 }
 474
 475 LoopInfo::LoopInfo(BasicBlock *Header, const LoopAttributes &Attrs,
 476                    const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc,
 477                    LoopInfo *Parent)
 478     : Header(Header), Attrs(Attrs), StartLoc(StartLoc), EndLoc(EndLoc),
 479       Parent(Parent) {
 480
 481   if (Attrs.IsParallel) {
 482     // Create an access group for this loop.
 483     LLVMContext &Ctx = Header->getContext();
 484     AccGroup = MDNode::getDistinct(Ctx, {});
 485   }
 486
 487   if (!Attrs.IsParallel && Attrs.VectorizeWidth == 0 &&
 488       Attrs.VectorizeScalable == LoopAttributes::Unspecified &&
 489       Attrs.InterleaveCount == 0 && Attrs.UnrollCount == 0 &&
 490       Attrs.UnrollAndJamCount == 0 && !Attrs.PipelineDisabled &&
 491       Attrs.PipelineInitiationInterval == 0 &&
 492       Attrs.VectorizePredicateEnable == LoopAttributes::Unspecified &&
 493       Attrs.VectorizeEnable == LoopAttributes::Unspecified &&
 494       Attrs.UnrollEnable == LoopAttributes::Unspecified &&
 495       Attrs.UnrollAndJamEnable == LoopAttributes::Unspecified &&
 496       Attrs.DistributeEnable == LoopAttributes::Unspecified && !StartLoc &&
 497       !EndLoc && !Attrs.MustProgress)
 498     return;
 499
 500   TempLoopID = MDNode::getTemporary(Header->getContext(), std::nullopt);
 501 }
 502
 503 void LoopInfo::finish() {
 504   // We did not annotate the loop body instructions because there are no
 505   // attributes for this loop.
 506   if (!TempLoopID)
 507     return;
 508
 509   MDNode *LoopID;
 510   LoopAttributes CurLoopAttr = Attrs;
 511   LLVMContext &Ctx = Header->getContext();
 512
 513   if (Parent && (Parent->Attrs.UnrollAndJamEnable ||
 514                  Parent->Attrs.UnrollAndJamCount != 0)) {
 515     // Parent unroll-and-jams this loop.
 516     // Split the transformations in those that happens before the unroll-and-jam
 517     // and those after.
 518
 519     LoopAttributes BeforeJam, AfterJam;
 520
 521     BeforeJam.IsParallel = AfterJam.IsParallel = Attrs.IsParallel;
 522
 523     BeforeJam.VectorizeWidth = Attrs.VectorizeWidth;
 524     BeforeJam.VectorizeScalable = Attrs.VectorizeScalable;
 525     BeforeJam.InterleaveCount = Attrs.InterleaveCount;
 526     BeforeJam.VectorizeEnable = Attrs.VectorizeEnable;
 527     BeforeJam.DistributeEnable = Attrs.DistributeEnable;
 528     BeforeJam.VectorizePredicateEnable = Attrs.VectorizePredicateEnable;
 529
 530     switch (Attrs.UnrollEnable) {
 531     case LoopAttributes::Unspecified:
 532     case LoopAttributes::Disable:
 533       BeforeJam.UnrollEnable = Attrs.UnrollEnable;
 534       AfterJam.UnrollEnable = Attrs.UnrollEnable;
 535       break;
 536     case LoopAttributes::Full:
 537       BeforeJam.UnrollEnable = LoopAttributes::Full;
 538       break;
 539     case LoopAttributes::Enable:
 540       AfterJam.UnrollEnable = LoopAttributes::Enable;
 541       break;
 542     }
 543
 544     AfterJam.VectorizePredicateEnable = Attrs.VectorizePredicateEnable;
 545     AfterJam.UnrollCount = Attrs.UnrollCount;
 546     AfterJam.PipelineDisabled = Attrs.PipelineDisabled;
 547     AfterJam.PipelineInitiationInterval = Attrs.PipelineInitiationInterval;
 548
 549     // If this loop is subject of an unroll-and-jam by the parent loop, and has
 550     // an unroll-and-jam annotation itself, we have to decide whether to first
 551     // apply the parent's unroll-and-jam or this loop's unroll-and-jam. The
 552     // UnrollAndJam pass processes loops from inner to outer, so we apply the
 553     // inner first.
 554     BeforeJam.UnrollAndJamCount = Attrs.UnrollAndJamCount;
 555     BeforeJam.UnrollAndJamEnable = Attrs.UnrollAndJamEnable;
 556
 557     // Set the inner followup metadata to process by the outer loop. Only
 558     // consider the first inner loop.
 559     if (!Parent->UnrollAndJamInnerFollowup) {
 560       // Splitting the attributes into a BeforeJam and an AfterJam part will
 561       // stop 'llvm.loop.isvectorized' (generated by vectorization in BeforeJam)
 562       // to be forwarded to the AfterJam part. We detect the situation here and
 563       // add it manually.
 564       SmallVector<Metadata *, 1> BeforeLoopProperties;
 565       if (BeforeJam.VectorizeEnable != LoopAttributes::Unspecified ||
 566           BeforeJam.VectorizePredicateEnable != LoopAttributes::Unspecified ||
 567           BeforeJam.InterleaveCount != 0 || BeforeJam.VectorizeWidth != 0 ||
 568           BeforeJam.VectorizeScalable == LoopAttributes::Enable)
 569         BeforeLoopProperties.push_back(
 570             MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.isvectorized")));
 571
 572       bool InnerFollowupHasTransform = false;
 573       MDNode *InnerFollowup = createMetadata(AfterJam, BeforeLoopProperties,
 574                                              InnerFollowupHasTransform);
 575       if (InnerFollowupHasTransform)
 576         Parent->UnrollAndJamInnerFollowup = InnerFollowup;
 577     }
 578
 579     CurLoopAttr = BeforeJam;
 580   }
 581
 582   bool HasUserTransforms = false;
 583   LoopID = createMetadata(CurLoopAttr, {}, HasUserTransforms);
 584   TempLoopID->replaceAllUsesWith(LoopID);
 585 }
 586
 587 void LoopInfoStack::push(BasicBlock *Header, const llvm::DebugLoc &StartLoc,
 588                          const llvm::DebugLoc &EndLoc) {
 589   Active.emplace_back(
 590       new LoopInfo(Header, StagedAttrs, StartLoc, EndLoc,
 591                    Active.empty() ? nullptr : Active.back().get()));
 592   // Clear the attributes so nested loops do not inherit them.
 593   StagedAttrs.clear();
 594 }
 595
 596 void LoopInfoStack::push(BasicBlock *Header, clang::ASTContext &Ctx,
 597                          const clang::CodeGenOptions &CGOpts,
 598                          ArrayRef<const clang::Attr *> Attrs,
 599                          const llvm::DebugLoc &StartLoc,
 600                          const llvm::DebugLoc &EndLoc, bool MustProgress) {
 601   // Identify loop hint attributes from Attrs.
 602   for (const auto *Attr : Attrs) {
 603     const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(Attr);
 604     const OpenCLUnrollHintAttr *OpenCLHint =
 605         dyn_cast<OpenCLUnrollHintAttr>(Attr);
 606
 607     // Skip non loop hint attributes
 608     if (!LH && !OpenCLHint) {
 609       continue;
 610     }
 611
 612     LoopHintAttr::OptionType Option = LoopHintAttr::Unroll;
 613     LoopHintAttr::LoopHintState State = LoopHintAttr::Disable;
 614     unsigned ValueInt = 1;
 615     // Translate opencl_unroll_hint attribute argument to
 616     // equivalent LoopHintAttr enums.
 617     // OpenCL v2.0 s6.11.5:
 618     // 0 - enable unroll (no argument).
 619     // 1 - disable unroll.
 620     // other positive integer n - unroll by n.
 621     if (OpenCLHint) {
 622       ValueInt = OpenCLHint->getUnrollHint();
 623       if (ValueInt == 0) {
 624         State = LoopHintAttr::Enable;
 625       } else if (ValueInt != 1) {
 626         Option = LoopHintAttr::UnrollCount;
 627         State = LoopHintAttr::Numeric;
 628       }
 629     } else if (LH) {
 630       auto *ValueExpr = LH->getValue();
 631       if (ValueExpr) {
 632         llvm::APSInt ValueAPS = ValueExpr->EvaluateKnownConstInt(Ctx);
 633         ValueInt = ValueAPS.getSExtValue();
 634       }
 635
 636       Option = LH->getOption();
 637       State = LH->getState();
 638     }
 639     switch (State) {
 640     case LoopHintAttr::Disable:
 641       switch (Option) {
 642       case LoopHintAttr::Vectorize:
 643         // Disable vectorization by specifying a width of 1.
 644         setVectorizeWidth(1);
 645         setVectorizeScalable(LoopAttributes::Unspecified);
 646         break;
 647       case LoopHintAttr::Interleave:
 648         // Disable interleaving by speciyfing a count of 1.
 649         setInterleaveCount(1);
 650         break;
 651       case LoopHintAttr::Unroll:
 652         setUnrollState(LoopAttributes::Disable);
 653         break;
 654       case LoopHintAttr::UnrollAndJam:
 655         setUnrollAndJamState(LoopAttributes::Disable);
 656         break;
 657       case LoopHintAttr::VectorizePredicate:
 658         setVectorizePredicateState(LoopAttributes::Disable);
 659         break;
 660       case LoopHintAttr::Distribute:
 661         setDistributeState(false);
 662         break;
 663       case LoopHintAttr::PipelineDisabled:
 664         setPipelineDisabled(true);
 665         break;
 666       case LoopHintAttr::UnrollCount:
 667       case LoopHintAttr::UnrollAndJamCount:
 668       case LoopHintAttr::VectorizeWidth:
 669       case LoopHintAttr::InterleaveCount:
 670       case LoopHintAttr::PipelineInitiationInterval:
 671         llvm_unreachable("Options cannot be disabled.");
 672         break;
 673       }
 674       break;
 675     case LoopHintAttr::Enable:
 676       switch (Option) {
 677       case LoopHintAttr::Vectorize:
 678       case LoopHintAttr::Interleave:
 679         setVectorizeEnable(true);
 680         break;
 681       case LoopHintAttr::Unroll:
 682         setUnrollState(LoopAttributes::Enable);
 683         break;
 684       case LoopHintAttr::UnrollAndJam:
 685         setUnrollAndJamState(LoopAttributes::Enable);
 686         break;
 687       case LoopHintAttr::VectorizePredicate:
 688         setVectorizePredicateState(LoopAttributes::Enable);
 689         break;
 690       case LoopHintAttr::Distribute:
 691         setDistributeState(true);
 692         break;
 693       case LoopHintAttr::UnrollCount:
 694       case LoopHintAttr::UnrollAndJamCount:
 695       case LoopHintAttr::VectorizeWidth:
 696       case LoopHintAttr::InterleaveCount:
 697       case LoopHintAttr::PipelineDisabled:
 698       case LoopHintAttr::PipelineInitiationInterval:
 699         llvm_unreachable("Options cannot enabled.");
 700         break;
 701       }
 702       break;
 703     case LoopHintAttr::AssumeSafety:
 704       switch (Option) {
 705       case LoopHintAttr::Vectorize:
 706       case LoopHintAttr::Interleave:
 707         // Apply "llvm.mem.parallel_loop_access" metadata to load/stores.
 708         setParallel(true);
 709         setVectorizeEnable(true);
 710         break;
 711       case LoopHintAttr::Unroll:
 712       case LoopHintAttr::UnrollAndJam:
 713       case LoopHintAttr::VectorizePredicate:
 714       case LoopHintAttr::UnrollCount:
 715       case LoopHintAttr::UnrollAndJamCount:
 716       case LoopHintAttr::VectorizeWidth:
 717       case LoopHintAttr::InterleaveCount:
 718       case LoopHintAttr::Distribute:
 719       case LoopHintAttr::PipelineDisabled:
 720       case LoopHintAttr::PipelineInitiationInterval:
 721         llvm_unreachable("Options cannot be used to assume mem safety.");
 722         break;
 723       }
 724       break;
 725     case LoopHintAttr::Full:
 726       switch (Option) {
 727       case LoopHintAttr::Unroll:
 728         setUnrollState(LoopAttributes::Full);
 729         break;
 730       case LoopHintAttr::UnrollAndJam:
 731         setUnrollAndJamState(LoopAttributes::Full);
 732         break;
 733       case LoopHintAttr::Vectorize:
 734       case LoopHintAttr::Interleave:
 735       case LoopHintAttr::UnrollCount:
 736       case LoopHintAttr::UnrollAndJamCount:
 737       case LoopHintAttr::VectorizeWidth:
 738       case LoopHintAttr::InterleaveCount:
 739       case LoopHintAttr::Distribute:
 740       case LoopHintAttr::PipelineDisabled:
 741       case LoopHintAttr::PipelineInitiationInterval:
 742       case LoopHintAttr::VectorizePredicate:
 743         llvm_unreachable("Options cannot be used with 'full' hint.");
 744         break;
 745       }
 746       break;
 747     case LoopHintAttr::FixedWidth:
 748     case LoopHintAttr::ScalableWidth:
 749       switch (Option) {
 750       case LoopHintAttr::VectorizeWidth:
 751         setVectorizeScalable(State == LoopHintAttr::ScalableWidth
 752                                  ? LoopAttributes::Enable
 753                                  : LoopAttributes::Disable);
 754         if (LH->getValue())
 755           setVectorizeWidth(ValueInt);
 756         break;
 757       default:
 758         llvm_unreachable("Options cannot be used with 'scalable' hint.");
 759         break;
 760       }
 761       break;
 762     case LoopHintAttr::Numeric:
 763       switch (Option) {
 764       case LoopHintAttr::InterleaveCount:
 765         setInterleaveCount(ValueInt);
 766         break;
 767       case LoopHintAttr::UnrollCount:
 768         setUnrollCount(ValueInt);
 769         break;
 770       case LoopHintAttr::UnrollAndJamCount:
 771         setUnrollAndJamCount(ValueInt);
 772         break;
 773       case LoopHintAttr::PipelineInitiationInterval:
 774         setPipelineInitiationInterval(ValueInt);
 775         break;
 776       case LoopHintAttr::Unroll:
 777       case LoopHintAttr::UnrollAndJam:
 778       case LoopHintAttr::VectorizePredicate:
 779       case LoopHintAttr::Vectorize:
 780       case LoopHintAttr::VectorizeWidth:
 781       case LoopHintAttr::Interleave:
 782       case LoopHintAttr::Distribute:
 783       case LoopHintAttr::PipelineDisabled:
 784         llvm_unreachable("Options cannot be assigned a value.");
 785         break;
 786       }
 787       break;
 788     }
 789   }
 790
 791   setMustProgress(MustProgress);
 792
 793   if (CGOpts.OptimizationLevel > 0)
 794     // Disable unrolling for the loop, if unrolling is disabled (via
 795     // -fno-unroll-loops) and no pragmas override the decision.
 796     if (!CGOpts.UnrollLoops &&
 797         (StagedAttrs.UnrollEnable == LoopAttributes::Unspecified &&
 798          StagedAttrs.UnrollCount == 0))
 799       setUnrollState(LoopAttributes::Disable);
 800
 801   /// Stage the attributes.
 802   push(Header, StartLoc, EndLoc);
 803 }
 804
 805 void LoopInfoStack::pop() {
 806   assert(!Active.empty() && "No active loops to pop");
 807   Active.back()->finish();
 808   Active.pop_back();
 809 }
 810
 811 void LoopInfoStack::InsertHelper(Instruction *I) const {
 812   if (I->mayReadOrWriteMemory()) {
 813     SmallVector<Metadata *, 4> AccessGroups;
 814     for (const auto &AL : Active) {
 815       // Here we assume that every loop that has an access group is parallel.
 816       if (MDNode *Group = AL->getAccessGroup())
 817         AccessGroups.push_back(Group);
 818     }
 819     MDNode *UnionMD = nullptr;
 820     if (AccessGroups.size() == 1)
 821       UnionMD = cast<MDNode>(AccessGroups[0]);
 822     else if (AccessGroups.size() >= 2)
 823       UnionMD = MDNode::get(I->getContext(), AccessGroups);
 824     I->setMetadata("llvm.access.group", UnionMD);
 825   }
 826
 827   if (!hasInfo())
 828     return;
 829
 830   const LoopInfo &L = getInfo();
 831   if (!L.getLoopID())
 832     return;
 833
 834   if (I->isTerminator()) {
 835     for (BasicBlock *Succ : successors(I))
 836       if (Succ == L.getHeader()) {
 837         I->setMetadata(llvm::LLVMContext::MD_loop, L.getLoopID());
 838         break;
 839       }
 840     return;
 841   }
 842 }