1 files changed, 803 insertions, 0 deletions
diff --git a/clang/lib/CodeGen/CGLoopInfo.cpp b/clang/lib/CodeGen/CGLoopInfo.cpp
new file mode 100644
index 000000000000..c21d4feee7a8
--- /dev/null
+++ b/clang/lib/CodeGen/CGLoopInfo.cpp
@@ -0,0 +1,803 @@
+//===---- CGLoopInfo.cpp - LLVM CodeGen for loop metadata -*- C++ -*-------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "CGLoopInfo.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Metadata.h"
+using namespace clang::CodeGen;
+using namespace llvm;
+
+MDNode *
+LoopInfo::createLoopPropertiesMetadata(ArrayRef<Metadata *> LoopProperties) {
+  LLVMContext &Ctx = Header->getContext();
+  SmallVector<Metadata *, 4> NewLoopProperties;
+  TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
+  NewLoopProperties.push_back(TempNode.get());
+  NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
+
+  MDNode *LoopID = MDNode::getDistinct(Ctx, NewLoopProperties);
+  LoopID->replaceOperandWith(0, LoopID);
+  return LoopID;
+}
+
+MDNode *LoopInfo::createPipeliningMetadata(const LoopAttributes &Attrs,
+                                           ArrayRef<Metadata *> LoopProperties,
+                                           bool &HasUserTransforms) {
+  LLVMContext &Ctx = Header->getContext();
+
+  Optional<bool> Enabled;
+  if (Attrs.PipelineDisabled)
+    Enabled = false;
+  else if (Attrs.PipelineInitiationInterval != 0)
+    Enabled = true;
+
+  if (Enabled != true) {
+    SmallVector<Metadata *, 4> NewLoopProperties;
+    if (Enabled == false) {
+      NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
+      NewLoopProperties.push_back(
+          MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.pipeline.disable"),
+                            ConstantAsMetadata::get(ConstantInt::get(
+                                llvm::Type::getInt1Ty(Ctx), 1))}));
+      LoopProperties = NewLoopProperties;
+    }
+    return createLoopPropertiesMetadata(LoopProperties);
+  }
+
+  SmallVector<Metadata *, 4> Args;
+  TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
+  Args.push_back(TempNode.get());
+  Args.append(LoopProperties.begin(), LoopProperties.end());
+
+  if (Attrs.PipelineInitiationInterval > 0) {
+    Metadata *Vals[] = {
+        MDString::get(Ctx, "llvm.loop.pipeline.initiationinterval"),
+        ConstantAsMetadata::get(ConstantInt::get(
+            llvm::Type::getInt32Ty(Ctx), Attrs.PipelineInitiationInterval))};
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  // No follow-up: This is the last transformation.
+
+  MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
+  LoopID->replaceOperandWith(0, LoopID);
+  HasUserTransforms = true;
+  return LoopID;
+}
+
+MDNode *
+LoopInfo::createPartialUnrollMetadata(const LoopAttributes &Attrs,
+                                      ArrayRef<Metadata *> LoopProperties,
+                                      bool &HasUserTransforms) {
+  LLVMContext &Ctx = Header->getContext();
+
+  Optional<bool> Enabled;
+  if (Attrs.UnrollEnable == LoopAttributes::Disable)
+    Enabled = false;
+  else if (Attrs.UnrollEnable == LoopAttributes::Full)
+    Enabled = None;
+  else if (Attrs.UnrollEnable != LoopAttributes::Unspecified ||
+           Attrs.UnrollCount != 0)
+    Enabled = true;
+
+  if (Enabled != true) {
+    // createFullUnrollMetadata will already have added llvm.loop.unroll.disable
+    // if unrolling is disabled.
+    return createPipeliningMetadata(Attrs, LoopProperties, HasUserTransforms);
+  }
+
+  SmallVector<Metadata *, 4> FollowupLoopProperties;
+
+  // Apply all loop properties to the unrolled loop.
+  FollowupLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
+
+  // Don't unroll an already unrolled loop.
+  FollowupLoopProperties.push_back(
+      MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.disable")));
+
+  bool FollowupHasTransforms = false;
+  MDNode *Followup = createPipeliningMetadata(Attrs, FollowupLoopProperties,
+                                              FollowupHasTransforms);
+
+  SmallVector<Metadata *, 4> Args;
+  TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
+  Args.push_back(TempNode.get());
+  Args.append(LoopProperties.begin(), LoopProperties.end());
+
+  // Setting unroll.count
+  if (Attrs.UnrollCount > 0) {
+    Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.unroll.count"),
+                        ConstantAsMetadata::get(ConstantInt::get(
+                            llvm::Type::getInt32Ty(Ctx), Attrs.UnrollCount))};
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  // Setting unroll.full or unroll.disable
+  if (Attrs.UnrollEnable == LoopAttributes::Enable) {
+    Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.unroll.enable")};
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  if (FollowupHasTransforms)
+    Args.push_back(MDNode::get(
+        Ctx, {MDString::get(Ctx, "llvm.loop.unroll.followup_all"), Followup}));
+
+  MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
+  LoopID->replaceOperandWith(0, LoopID);
+  HasUserTransforms = true;
+  return LoopID;
+}
+
+MDNode *
+LoopInfo::createUnrollAndJamMetadata(const LoopAttributes &Attrs,
+                                     ArrayRef<Metadata *> LoopProperties,
+                                     bool &HasUserTransforms) {
+  LLVMContext &Ctx = Header->getContext();
+
+  Optional<bool> Enabled;
+  if (Attrs.UnrollAndJamEnable == LoopAttributes::Disable)
+    Enabled = false;
+  else if (Attrs.UnrollAndJamEnable == LoopAttributes::Enable ||
+           Attrs.UnrollAndJamCount != 0)
+    Enabled = true;
+
+  if (Enabled != true) {
+    SmallVector<Metadata *, 4> NewLoopProperties;
+    if (Enabled == false) {
+      NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
+      NewLoopProperties.push_back(MDNode::get(
+          Ctx, MDString::get(Ctx, "llvm.loop.unroll_and_jam.disable")));
+      LoopProperties = NewLoopProperties;
+    }
+    return createPartialUnrollMetadata(Attrs, LoopProperties,
+                                       HasUserTransforms);
+  }
+
+  SmallVector<Metadata *, 4> FollowupLoopProperties;
+  FollowupLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
+  FollowupLoopProperties.push_back(
+      MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll_and_jam.disable")));
+
+  bool FollowupHasTransforms = false;
+  MDNode *Followup = createPartialUnrollMetadata(Attrs, FollowupLoopProperties,
+                                                 FollowupHasTransforms);
+
+  SmallVector<Metadata *, 4> Args;
+  TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
+  Args.push_back(TempNode.get());
+  Args.append(LoopProperties.begin(), LoopProperties.end());
+
+  // Setting unroll_and_jam.count
+  if (Attrs.UnrollAndJamCount > 0) {
+    Metadata *Vals[] = {
+        MDString::get(Ctx, "llvm.loop.unroll_and_jam.count"),
+        ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt32Ty(Ctx),
+                                                 Attrs.UnrollAndJamCount))};
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  if (Attrs.UnrollAndJamEnable == LoopAttributes::Enable) {
+    Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.unroll_and_jam.enable")};
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  if (FollowupHasTransforms)
+    Args.push_back(MDNode::get(
+        Ctx, {MDString::get(Ctx, "llvm.loop.unroll_and_jam.followup_outer"),
+              Followup}));
+
+  if (UnrollAndJamInnerFollowup)
+    Args.push_back(MDNode::get(
+        Ctx, {MDString::get(Ctx, "llvm.loop.unroll_and_jam.followup_inner"),
+              UnrollAndJamInnerFollowup}));
+
+  MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
+  LoopID->replaceOperandWith(0, LoopID);
+  HasUserTransforms = true;
+  return LoopID;
+}
+
+MDNode *
+LoopInfo::createLoopVectorizeMetadata(const LoopAttributes &Attrs,
+                                      ArrayRef<Metadata *> LoopProperties,
+                                      bool &HasUserTransforms) {
+  LLVMContext &Ctx = Header->getContext();
+
+  Optional<bool> Enabled;
+  if (Attrs.VectorizeEnable == LoopAttributes::Disable)
+    Enabled = false;
+  else if (Attrs.VectorizeEnable != LoopAttributes::Unspecified ||
+           Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified ||
+           Attrs.InterleaveCount != 0 || Attrs.VectorizeWidth != 0)
+    Enabled = true;
+
+  if (Enabled != true) {
+    SmallVector<Metadata *, 4> NewLoopProperties;
+    if (Enabled == false) {
+      NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
+      NewLoopProperties.push_back(
+          MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.vectorize.enable"),
+                            ConstantAsMetadata::get(ConstantInt::get(
+                                llvm::Type::getInt1Ty(Ctx), 0))}));
+      LoopProperties = NewLoopProperties;
+    }
+    return createUnrollAndJamMetadata(Attrs, LoopProperties, HasUserTransforms);
+  }
+
+  // Apply all loop properties to the vectorized loop.
+  SmallVector<Metadata *, 4> FollowupLoopProperties;
+  FollowupLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
+
+  // Don't vectorize an already vectorized loop.
+  FollowupLoopProperties.push_back(
+      MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.isvectorized")));
+
+  bool FollowupHasTransforms = false;
+  MDNode *Followup = createUnrollAndJamMetadata(Attrs, FollowupLoopProperties,
+                                                FollowupHasTransforms);
+
+  SmallVector<Metadata *, 4> Args;
+  TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
+  Args.push_back(TempNode.get());
+  Args.append(LoopProperties.begin(), LoopProperties.end());
+
+  // Setting vectorize.predicate
+  bool IsVectorPredicateEnabled = false;
+  if (Attrs.VectorizePredicateEnable != LoopAttributes::Unspecified &&
+      Attrs.VectorizeEnable != LoopAttributes::Disable &&
+      Attrs.VectorizeWidth < 1) {
+
+    IsVectorPredicateEnabled =
+        (Attrs.VectorizePredicateEnable == LoopAttributes::Enable);
+
+    Metadata *Vals[] = {
+        MDString::get(Ctx, "llvm.loop.vectorize.predicate.enable"),
+        ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt1Ty(Ctx),
+                                                 IsVectorPredicateEnabled))};
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  // Setting vectorize.width
+  if (Attrs.VectorizeWidth > 0) {
+    // This implies vectorize.enable = true, but only add it when it is not
+    // already enabled.
+    if (Attrs.VectorizeEnable != LoopAttributes::Enable)
+      Args.push_back(
+          MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.vectorize.enable"),
+                            ConstantAsMetadata::get(ConstantInt::get(
+                                llvm::Type::getInt1Ty(Ctx), 1))}));
+
+    Metadata *Vals[] = {
+        MDString::get(Ctx, "llvm.loop.vectorize.width"),
+        ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt32Ty(Ctx),
+                                                 Attrs.VectorizeWidth))};
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  // Setting interleave.count
+  if (Attrs.InterleaveCount > 0) {
+    Metadata *Vals[] = {
+        MDString::get(Ctx, "llvm.loop.interleave.count"),
+        ConstantAsMetadata::get(ConstantInt::get(llvm::Type::getInt32Ty(Ctx),
+                                                 Attrs.InterleaveCount))};
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  // Setting vectorize.enable
+  if (Attrs.VectorizeEnable != LoopAttributes::Unspecified ||
+      IsVectorPredicateEnabled) {
+    Metadata *Vals[] = {
+        MDString::get(Ctx, "llvm.loop.vectorize.enable"),
+        ConstantAsMetadata::get(ConstantInt::get(
+            llvm::Type::getInt1Ty(Ctx),
+            IsVectorPredicateEnabled
+                ? true
+                : (Attrs.VectorizeEnable == LoopAttributes::Enable)))};
+    Args.push_back(MDNode::get(Ctx, Vals));
+  }
+
+  if (FollowupHasTransforms)
+    Args.push_back(MDNode::get(
+        Ctx,
+        {MDString::get(Ctx, "llvm.loop.vectorize.followup_all"), Followup}));
+
+  MDNode *LoopID = MDNode::get(Ctx, Args);
+  LoopID->replaceOperandWith(0, LoopID);
+  HasUserTransforms = true;
+  return LoopID;
+}
+
+MDNode *
+LoopInfo::createLoopDistributeMetadata(const LoopAttributes &Attrs,
+                                       ArrayRef<Metadata *> LoopProperties,
+                                       bool &HasUserTransforms) {
+  LLVMContext &Ctx = Header->getContext();
+
+  Optional<bool> Enabled;
+  if (Attrs.DistributeEnable == LoopAttributes::Disable)
+    Enabled = false;
+  if (Attrs.DistributeEnable == LoopAttributes::Enable)
+    Enabled = true;
+
+  if (Enabled != true) {
+    SmallVector<Metadata *, 4> NewLoopProperties;
+    if (Enabled == false) {
+      NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
+      NewLoopProperties.push_back(
+          MDNode::get(Ctx, {MDString::get(Ctx, "llvm.loop.distribute.enable"),
+                            ConstantAsMetadata::get(ConstantInt::get(
+                                llvm::Type::getInt1Ty(Ctx), 0))}));
+      LoopProperties = NewLoopProperties;
+    }
+    return createLoopVectorizeMetadata(Attrs, LoopProperties,
+                                       HasUserTransforms);
+  }
+
+  bool FollowupHasTransforms = false;
+  MDNode *Followup =
+      createLoopVectorizeMetadata(Attrs, LoopProperties, FollowupHasTransforms);
+
+  SmallVector<Metadata *, 4> Args;
+  TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
+  Args.push_back(TempNode.get());
+  Args.append(LoopProperties.begin(), LoopProperties.end());
+
+  Metadata *Vals[] = {MDString::get(Ctx, "llvm.loop.distribute.enable"),
+                      ConstantAsMetadata::get(ConstantInt::get(
+                          llvm::Type::getInt1Ty(Ctx),
+                          (Attrs.DistributeEnable == LoopAttributes::Enable)))};
+  Args.push_back(MDNode::get(Ctx, Vals));
+
+  if (FollowupHasTransforms)
+    Args.push_back(MDNode::get(
+        Ctx,
+        {MDString::get(Ctx, "llvm.loop.distribute.followup_all"), Followup}));
+
+  MDNode *LoopID = MDNode::get(Ctx, Args);
+  LoopID->replaceOperandWith(0, LoopID);
+  HasUserTransforms = true;
+  return LoopID;
+}
+
+MDNode *LoopInfo::createFullUnrollMetadata(const LoopAttributes &Attrs,
+                                           ArrayRef<Metadata *> LoopProperties,
+                                           bool &HasUserTransforms) {
+  LLVMContext &Ctx = Header->getContext();
+
+  Optional<bool> Enabled;
+  if (Attrs.UnrollEnable == LoopAttributes::Disable)
+    Enabled = false;
+  else if (Attrs.UnrollEnable == LoopAttributes::Full)
+    Enabled = true;
+
+  if (Enabled != true) {
+    SmallVector<Metadata *, 4> NewLoopProperties;
+    if (Enabled == false) {
+      NewLoopProperties.append(LoopProperties.begin(), LoopProperties.end());
+      NewLoopProperties.push_back(
+          MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.disable")));
+      LoopProperties = NewLoopProperties;
+    }
+    return createLoopDistributeMetadata(Attrs, LoopProperties,
+                                        HasUserTransforms);
+  }
+
+  SmallVector<Metadata *, 4> Args;
+  TempMDTuple TempNode = MDNode::getTemporary(Ctx, None);
+  Args.push_back(TempNode.get());
+  Args.append(LoopProperties.begin(), LoopProperties.end());
+  Args.push_back(MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.unroll.full")));
+
+  // No follow-up: there is no loop after full unrolling.
+  // TODO: Warn if there are transformations after full unrolling.
+
+  MDNode *LoopID = MDNode::getDistinct(Ctx, Args);
+  LoopID->replaceOperandWith(0, LoopID);
+  HasUserTransforms = true;
+  return LoopID;
+}
+
+MDNode *LoopInfo::createMetadata(
+    const LoopAttributes &Attrs,
+    llvm::ArrayRef<llvm::Metadata *> AdditionalLoopProperties,
+    bool &HasUserTransforms) {
+  SmallVector<Metadata *, 3> LoopProperties;
+
+  // If we have a valid start debug location for the loop, add it.
+  if (StartLoc) {
+    LoopProperties.push_back(StartLoc.getAsMDNode());
+
+    // If we also have a valid end debug location for the loop, add it.
+    if (EndLoc)
+      LoopProperties.push_back(EndLoc.getAsMDNode());
+  }
+
+  assert(!!AccGroup == Attrs.IsParallel &&
+         "There must be an access group iff the loop is parallel");
+  if (Attrs.IsParallel) {
+    LLVMContext &Ctx = Header->getContext();
+    LoopProperties.push_back(MDNode::get(
+        Ctx, {MDString::get(Ctx, "llvm.loop.parallel_accesses"), AccGroup}));
+  }
+
+  LoopProperties.insert(LoopProperties.end(), AdditionalLoopProperties.begin(),
+                        AdditionalLoopProperties.end());
+  return createFullUnrollMetadata(Attrs, LoopProperties, HasUserTransforms);
+}
+
+LoopAttributes::LoopAttributes(bool IsParallel)
+    : IsParallel(IsParallel), VectorizeEnable(LoopAttributes::Unspecified),
+      UnrollEnable(LoopAttributes::Unspecified),
+      UnrollAndJamEnable(LoopAttributes::Unspecified),
+      VectorizePredicateEnable(LoopAttributes::Unspecified), VectorizeWidth(0),
+      InterleaveCount(0), UnrollCount(0), UnrollAndJamCount(0),
+      DistributeEnable(LoopAttributes::Unspecified), PipelineDisabled(false),
+      PipelineInitiationInterval(0) {}
+
+void LoopAttributes::clear() {
+  IsParallel = false;
+  VectorizeWidth = 0;
+  InterleaveCount = 0;
+  UnrollCount = 0;
+  UnrollAndJamCount = 0;
+  VectorizeEnable = LoopAttributes::Unspecified;
+  UnrollEnable = LoopAttributes::Unspecified;
+  UnrollAndJamEnable = LoopAttributes::Unspecified;
+  VectorizePredicateEnable = LoopAttributes::Unspecified;
+  DistributeEnable = LoopAttributes::Unspecified;
+  PipelineDisabled = false;
+  PipelineInitiationInterval = 0;
+}
+
+LoopInfo::LoopInfo(BasicBlock *Header, const LoopAttributes &Attrs,
+                   const llvm::DebugLoc &StartLoc, const llvm::DebugLoc &EndLoc,
+                   LoopInfo *Parent)
+    : Header(Header), Attrs(Attrs), StartLoc(StartLoc), EndLoc(EndLoc),
+      Parent(Parent) {
+
+  if (Attrs.IsParallel) {
+    // Create an access group for this loop.
+    LLVMContext &Ctx = Header->getContext();
+    AccGroup = MDNode::getDistinct(Ctx, {});
+  }
+
+  if (!Attrs.IsParallel && Attrs.VectorizeWidth == 0 &&
+      Attrs.InterleaveCount == 0 && Attrs.UnrollCount == 0 &&
+      Attrs.UnrollAndJamCount == 0 && !Attrs.PipelineDisabled &&
+      Attrs.PipelineInitiationInterval == 0 &&
+      Attrs.VectorizePredicateEnable == LoopAttributes::Unspecified &&
+      Attrs.VectorizeEnable == LoopAttributes::Unspecified &&
+      Attrs.UnrollEnable == LoopAttributes::Unspecified &&
+      Attrs.UnrollAndJamEnable == LoopAttributes::Unspecified &&
+      Attrs.DistributeEnable == LoopAttributes::Unspecified && !StartLoc &&
+      !EndLoc)
+    return;
+
+  TempLoopID = MDNode::getTemporary(Header->getContext(), None);
+}
+
+void LoopInfo::finish() {
+  // We did not annotate the loop body instructions because there are no
+  // attributes for this loop.
+  if (!TempLoopID)
+    return;
+
+  MDNode *LoopID;
+  LoopAttributes CurLoopAttr = Attrs;
+  LLVMContext &Ctx = Header->getContext();
+
+  if (Parent && (Parent->Attrs.UnrollAndJamEnable ||
+                 Parent->Attrs.UnrollAndJamCount != 0)) {
+    // Parent unroll-and-jams this loop.
+    // Split the transformations in those that happens before the unroll-and-jam
+    // and those after.
+
+    LoopAttributes BeforeJam, AfterJam;
+
+    BeforeJam.IsParallel = AfterJam.IsParallel = Attrs.IsParallel;
+
+    BeforeJam.VectorizeWidth = Attrs.VectorizeWidth;
+    BeforeJam.InterleaveCount = Attrs.InterleaveCount;
+    BeforeJam.VectorizeEnable = Attrs.VectorizeEnable;
+    BeforeJam.DistributeEnable = Attrs.DistributeEnable;
+    BeforeJam.VectorizePredicateEnable = Attrs.VectorizePredicateEnable;
+
+    switch (Attrs.UnrollEnable) {
+    case LoopAttributes::Unspecified:
+    case LoopAttributes::Disable:
+      BeforeJam.UnrollEnable = Attrs.UnrollEnable;
+      AfterJam.UnrollEnable = Attrs.UnrollEnable;
+      break;
+    case LoopAttributes::Full:
+      BeforeJam.UnrollEnable = LoopAttributes::Full;
+      break;
+    case LoopAttributes::Enable:
+      AfterJam.UnrollEnable = LoopAttributes::Enable;
+      break;
+    }
+
+    AfterJam.VectorizePredicateEnable = Attrs.VectorizePredicateEnable;
+    AfterJam.UnrollCount = Attrs.UnrollCount;
+    AfterJam.PipelineDisabled = Attrs.PipelineDisabled;
+    AfterJam.PipelineInitiationInterval = Attrs.PipelineInitiationInterval;
+
+    // If this loop is subject of an unroll-and-jam by the parent loop, and has
+    // an unroll-and-jam annotation itself, we have to decide whether to first
+    // apply the parent's unroll-and-jam or this loop's unroll-and-jam. The
+    // UnrollAndJam pass processes loops from inner to outer, so we apply the
+    // inner first.
+    BeforeJam.UnrollAndJamCount = Attrs.UnrollAndJamCount;
+    BeforeJam.UnrollAndJamEnable = Attrs.UnrollAndJamEnable;
+
+    // Set the inner followup metadata to process by the outer loop. Only
+    // consider the first inner loop.
+    if (!Parent->UnrollAndJamInnerFollowup) {
+      // Splitting the attributes into a BeforeJam and an AfterJam part will
+      // stop 'llvm.loop.isvectorized' (generated by vectorization in BeforeJam)
+      // to be forwarded to the AfterJam part. We detect the situation here and
+      // add it manually.
+      SmallVector<Metadata *, 1> BeforeLoopProperties;
+      if (BeforeJam.VectorizeEnable != LoopAttributes::Unspecified ||
+          BeforeJam.VectorizePredicateEnable != LoopAttributes::Unspecified ||
+          BeforeJam.InterleaveCount != 0 || BeforeJam.VectorizeWidth != 0)
+        BeforeLoopProperties.push_back(
+            MDNode::get(Ctx, MDString::get(Ctx, "llvm.loop.isvectorized")));
+
+      bool InnerFollowupHasTransform = false;
+      MDNode *InnerFollowup = createMetadata(AfterJam, BeforeLoopProperties,
+                                             InnerFollowupHasTransform);
+      if (InnerFollowupHasTransform)
+        Parent->UnrollAndJamInnerFollowup = InnerFollowup;
+    }
+
+    CurLoopAttr = BeforeJam;
+  }
+
+  bool HasUserTransforms = false;
+  LoopID = createMetadata(CurLoopAttr, {}, HasUserTransforms);
+  TempLoopID->replaceAllUsesWith(LoopID);
+}
+
+void LoopInfoStack::push(BasicBlock *Header, const llvm::DebugLoc &StartLoc,
+                         const llvm::DebugLoc &EndLoc) {
+  Active.emplace_back(
+      new LoopInfo(Header, StagedAttrs, StartLoc, EndLoc,
+                   Active.empty() ? nullptr : Active.back().get()));
+  // Clear the attributes so nested loops do not inherit them.
+  StagedAttrs.clear();
+}
+
+void LoopInfoStack::push(BasicBlock *Header, clang::ASTContext &Ctx,
+                         ArrayRef<const clang::Attr *> Attrs,
+                         const llvm::DebugLoc &StartLoc,
+                         const llvm::DebugLoc &EndLoc) {
+
+  // Identify loop hint attributes from Attrs.
+  for (const auto *Attr : Attrs) {
+    const LoopHintAttr *LH = dyn_cast<LoopHintAttr>(Attr);
+    const OpenCLUnrollHintAttr *OpenCLHint =
+        dyn_cast<OpenCLUnrollHintAttr>(Attr);
+
+    // Skip non loop hint attributes
+    if (!LH && !OpenCLHint) {
+      continue;
+    }
+
+    LoopHintAttr::OptionType Option = LoopHintAttr::Unroll;
+    LoopHintAttr::LoopHintState State = LoopHintAttr::Disable;
+    unsigned ValueInt = 1;
+    // Translate opencl_unroll_hint attribute argument to
+    // equivalent LoopHintAttr enums.
+    // OpenCL v2.0 s6.11.5:
+    // 0 - enable unroll (no argument).
+    // 1 - disable unroll.
+    // other positive integer n - unroll by n.
+    if (OpenCLHint) {
+      ValueInt = OpenCLHint->getUnrollHint();
+      if (ValueInt == 0) {
+        State = LoopHintAttr::Enable;
+      } else if (ValueInt != 1) {
+        Option = LoopHintAttr::UnrollCount;
+        State = LoopHintAttr::Numeric;
+      }
+    } else if (LH) {
+      auto *ValueExpr = LH->getValue();
+      if (ValueExpr) {
+        llvm::APSInt ValueAPS = ValueExpr->EvaluateKnownConstInt(Ctx);
+        ValueInt = ValueAPS.getSExtValue();
+      }
+
+      Option = LH->getOption();
+      State = LH->getState();
+    }
+    switch (State) {
+    case LoopHintAttr::Disable:
+      switch (Option) {
+      case LoopHintAttr::Vectorize:
+        // Disable vectorization by specifying a width of 1.
+        setVectorizeWidth(1);
+        break;
+      case LoopHintAttr::Interleave:
+        // Disable interleaving by speciyfing a count of 1.
+        setInterleaveCount(1);
+        break;
+      case LoopHintAttr::Unroll:
+        setUnrollState(LoopAttributes::Disable);
+        break;
+      case LoopHintAttr::UnrollAndJam:
+        setUnrollAndJamState(LoopAttributes::Disable);
+        break;
+      case LoopHintAttr::VectorizePredicate:
+        setVectorizePredicateState(LoopAttributes::Disable);
+        break;
+      case LoopHintAttr::Distribute:
+        setDistributeState(false);
+        break;
+      case LoopHintAttr::PipelineDisabled:
+        setPipelineDisabled(true);
+        break;
+      case LoopHintAttr::UnrollCount:
+      case LoopHintAttr::UnrollAndJamCount:
+      case LoopHintAttr::VectorizeWidth:
+      case LoopHintAttr::InterleaveCount:
+      case LoopHintAttr::PipelineInitiationInterval:
+        llvm_unreachable("Options cannot be disabled.");
+        break;
+      }
+      break;
+    case LoopHintAttr::Enable:
+      switch (Option) {
+      case LoopHintAttr::Vectorize:
+      case LoopHintAttr::Interleave:
+        setVectorizeEnable(true);
+        break;
+      case LoopHintAttr::Unroll:
+        setUnrollState(LoopAttributes::Enable);
+        break;
+      case LoopHintAttr::UnrollAndJam:
+        setUnrollAndJamState(LoopAttributes::Enable);
+        break;
+      case LoopHintAttr::VectorizePredicate:
+        setVectorizePredicateState(LoopAttributes::Enable);
+        break;
+      case LoopHintAttr::Distribute:
+        setDistributeState(true);
+        break;
+      case LoopHintAttr::UnrollCount:
+      case LoopHintAttr::UnrollAndJamCount:
+      case LoopHintAttr::VectorizeWidth:
+      case LoopHintAttr::InterleaveCount:
+      case LoopHintAttr::PipelineDisabled:
+      case LoopHintAttr::PipelineInitiationInterval:
+        llvm_unreachable("Options cannot enabled.");
+        break;
+      }
+      break;
+    case LoopHintAttr::AssumeSafety:
+      switch (Option) {
+      case LoopHintAttr::Vectorize:
+      case LoopHintAttr::Interleave:
+        // Apply "llvm.mem.parallel_loop_access" metadata to load/stores.
+        setParallel(true);
+        setVectorizeEnable(true);
+        break;
+      case LoopHintAttr::Unroll:
+      case LoopHintAttr::UnrollAndJam:
+      case LoopHintAttr::VectorizePredicate:
+      case LoopHintAttr::UnrollCount:
+      case LoopHintAttr::UnrollAndJamCount:
+      case LoopHintAttr::VectorizeWidth:
+      case LoopHintAttr::InterleaveCount:
+      case LoopHintAttr::Distribute:
+      case LoopHintAttr::PipelineDisabled:
+      case LoopHintAttr::PipelineInitiationInterval:
+        llvm_unreachable("Options cannot be used to assume mem safety.");
+        break;
+      }
+      break;
+    case LoopHintAttr::Full:
+      switch (Option) {
+      case LoopHintAttr::Unroll:
+        setUnrollState(LoopAttributes::Full);
+        break;
+      case LoopHintAttr::UnrollAndJam:
+        setUnrollAndJamState(LoopAttributes::Full);
+        break;
+      case LoopHintAttr::Vectorize:
+      case LoopHintAttr::Interleave:
+      case LoopHintAttr::UnrollCount:
+      case LoopHintAttr::UnrollAndJamCount:
+      case LoopHintAttr::VectorizeWidth:
+      case LoopHintAttr::InterleaveCount:
+      case LoopHintAttr::Distribute:
+      case LoopHintAttr::PipelineDisabled:
+      case LoopHintAttr::PipelineInitiationInterval:
+      case LoopHintAttr::VectorizePredicate:
+        llvm_unreachable("Options cannot be used with 'full' hint.");
+        break;
+      }
+      break;
+    case LoopHintAttr::Numeric:
+      switch (Option) {
+      case LoopHintAttr::VectorizeWidth:
+        setVectorizeWidth(ValueInt);
+        break;
+      case LoopHintAttr::InterleaveCount:
+        setInterleaveCount(ValueInt);
+        break;
+      case LoopHintAttr::UnrollCount:
+        setUnrollCount(ValueInt);
+        break;
+      case LoopHintAttr::UnrollAndJamCount:
+        setUnrollAndJamCount(ValueInt);
+        break;
+      case LoopHintAttr::PipelineInitiationInterval:
+        setPipelineInitiationInterval(ValueInt);
+        break;
+      case LoopHintAttr::Unroll:
+      case LoopHintAttr::UnrollAndJam:
+      case LoopHintAttr::VectorizePredicate:
+      case LoopHintAttr::Vectorize:
+      case LoopHintAttr::Interleave:
+      case LoopHintAttr::Distribute:
+      case LoopHintAttr::PipelineDisabled:
+        llvm_unreachable("Options cannot be assigned a value.");
+        break;
+      }
+      break;
+    }
+  }
+
+  /// Stage the attributes.
+  push(Header, StartLoc, EndLoc);
+}
+
+void LoopInfoStack::pop() {
+  assert(!Active.empty() && "No active loops to pop");
+  Active.back()->finish();
+  Active.pop_back();
+}
+
+void LoopInfoStack::InsertHelper(Instruction *I) const {
+  if (I->mayReadOrWriteMemory()) {
+    SmallVector<Metadata *, 4> AccessGroups;
+    for (const auto &AL : Active) {
+      // Here we assume that every loop that has an access group is parallel.
+      if (MDNode *Group = AL->getAccessGroup())
+        AccessGroups.push_back(Group);
+    }
+    MDNode *UnionMD = nullptr;
+    if (AccessGroups.size() == 1)
+      UnionMD = cast<MDNode>(AccessGroups[0]);
+    else if (AccessGroups.size() >= 2)
+      UnionMD = MDNode::get(I->getContext(), AccessGroups);
+    I->setMetadata("llvm.access.group", UnionMD);
+  }
+
+  if (!hasInfo())
+    return;
+
+  const LoopInfo &L = getInfo();
+  if (!L.getLoopID())
+    return;
+
+  if (I->isTerminator()) {
+    for (BasicBlock *Succ : successors(I))
+      if (Succ == L.getHeader()) {
+        I->setMetadata(llvm::LLVMContext::MD_loop, L.getLoopID());
+        break;
+      }
+    return;
+  }
+}