llvm/lib/IR/MemoryModelRelaxationAnnotations.cpp

   1 //===- MemoryModelRelaxationAnnotations.cpp ---------------------*- 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 "llvm/IR/MemoryModelRelaxationAnnotations.h"
  10 #include "llvm/IR/Instructions.h"
  11 #include "llvm/IR/Metadata.h"
  12 #include "llvm/Support/Debug.h"
  13 #include "llvm/Support/raw_ostream.h"
  14
  15 using namespace llvm;
  16
  17 //===- MMRAMetadata -------------------------------------------------------===//
  18
  19 MMRAMetadata::MMRAMetadata(const Instruction &I)
  20     : MMRAMetadata(I.getMetadata(LLVMContext::MD_mmra)) {}
  21
  22 MMRAMetadata::MMRAMetadata(MDNode *MD) {
  23   if (!MD)
  24     return;
  25
  26   // TODO: Split this into a "tryParse" function that can return an err.
  27   // CTor can use the tryParse & just fatal on err.
  28
  29   MDTuple *Tuple = dyn_cast<MDTuple>(MD);
  30   assert(Tuple && "Invalid MMRA structure");
  31
  32   const auto HandleTagMD = [this](MDNode *TagMD) {
  33     Tags.insert({cast<MDString>(TagMD->getOperand(0))->getString(),
  34                  cast<MDString>(TagMD->getOperand(1))->getString()});
  35   };
  36
  37   if (isTagMD(Tuple)) {
  38     HandleTagMD(Tuple);
  39     return;
  40   }
  41
  42   for (const MDOperand &Op : Tuple->operands()) {
  43     MDNode *MDOp = cast<MDNode>(Op.get());
  44     assert(isTagMD(MDOp));
  45     HandleTagMD(MDOp);
  46   }
  47 }
  48
  49 bool MMRAMetadata::isTagMD(const Metadata *MD) {
  50   if (auto *Tuple = dyn_cast<MDTuple>(MD)) {
  51     return Tuple->getNumOperands() == 2 &&
  52            isa<MDString>(Tuple->getOperand(0)) &&
  53            isa<MDString>(Tuple->getOperand(1));
  54   }
  55   return false;
  56 }
  57
  58 MDTuple *MMRAMetadata::getTagMD(LLVMContext &Ctx, StringRef Prefix,
  59                                 StringRef Suffix) {
  60   return MDTuple::get(Ctx,
  61                       {MDString::get(Ctx, Prefix), MDString::get(Ctx, Suffix)});
  62 }
  63
  64 MDTuple *MMRAMetadata::getMD(LLVMContext &Ctx,
  65                              ArrayRef<MMRAMetadata::TagT> Tags) {
  66   if (Tags.empty())
  67     return nullptr;
  68
  69   if (Tags.size() == 1)
  70     return getTagMD(Ctx, Tags.front());
  71
  72   SmallVector<Metadata *> MMRAs;
  73   for (const auto &Tag : Tags)
  74     MMRAs.push_back(getTagMD(Ctx, Tag));
  75   return MDTuple::get(Ctx, MMRAs);
  76 }
  77
  78 MDNode *MMRAMetadata::combine(LLVMContext &Ctx, const MMRAMetadata &A,
  79                               const MMRAMetadata &B) {
  80   // Let A and B be two tags set, and U be the prefix-wise union of A and B.
  81   // For every unique tag prefix P present in A or B:
  82   // * If either A or B has no tags with prefix P, no tags with prefix
  83   //   P are added to U.
  84   // * If both A and B have at least one tag with prefix P, all tags with prefix
  85   //   P from both sets are added to U.
  86
  87   SmallVector<Metadata *> Result;
  88
  89   for (const auto &[P, S] : A) {
  90     if (B.hasTagWithPrefix(P))
  91       Result.push_back(getTagMD(Ctx, P, S));
  92   }
  93   for (const auto &[P, S] : B) {
  94     if (A.hasTagWithPrefix(P))
  95       Result.push_back(getTagMD(Ctx, P, S));
  96   }
  97
  98   return MDTuple::get(Ctx, Result);
  99 }
 100
 101 bool MMRAMetadata::hasTag(StringRef Prefix, StringRef Suffix) const {
 102   return Tags.count({Prefix, Suffix});
 103 }
 104
 105 bool MMRAMetadata::isCompatibleWith(const MMRAMetadata &Other) const {
 106   // Two sets of tags are compatible iff, for every unique tag prefix P
 107   // present in at least one set:
 108   //   - the other set contains no tag with prefix P, or
 109   //   - at least one tag with prefix P is common to both sets.
 110
 111   StringMap<bool> PrefixStatuses;
 112   for (const auto &[P, S] : Tags)
 113     PrefixStatuses[P] |= (Other.hasTag(P, S) || !Other.hasTagWithPrefix(P));
 114   for (const auto &[P, S] : Other)
 115     PrefixStatuses[P] |= (hasTag(P, S) || !hasTagWithPrefix(P));
 116
 117   for (auto &[Prefix, Status] : PrefixStatuses) {
 118     if (!Status)
 119       return false;
 120   }
 121
 122   return true;
 123 }
 124
 125 bool MMRAMetadata::hasTagWithPrefix(StringRef Prefix) const {
 126   for (const auto &[P, S] : Tags)
 127     if (P == Prefix)
 128       return true;
 129   return false;
 130 }
 131
 132 MMRAMetadata::const_iterator MMRAMetadata::begin() const {
 133   return Tags.begin();
 134 }
 135
 136 MMRAMetadata::const_iterator MMRAMetadata::end() const { return Tags.end(); }
 137
 138 bool MMRAMetadata::empty() const { return Tags.empty(); }
 139
 140 unsigned MMRAMetadata::size() const { return Tags.size(); }
 141
 142 void MMRAMetadata::print(raw_ostream &OS) const {
 143   bool IsFirst = true;
 144   // TODO: use map_iter + join
 145   for (const auto &[P, S] : Tags) {
 146     if (IsFirst)
 147       IsFirst = false;
 148     else
 149       OS << ", ";
 150     OS << P << ":" << S;
 151   }
 152 }
 153
 154 LLVM_DUMP_METHOD
 155 void MMRAMetadata::dump() const { print(dbgs()); }
 156
 157 //===- Helpers ------------------------------------------------------------===//
 158
 159 static bool isReadWriteMemCall(const Instruction &I) {
 160   if (const auto *C = dyn_cast<CallBase>(&I))
 161     return C->mayReadOrWriteMemory() ||
 162            !C->getMemoryEffects().doesNotAccessMemory();
 163   return false;
 164 }
 165
 166 bool llvm::canInstructionHaveMMRAs(const Instruction &I) {
 167   return isa<LoadInst>(I) || isa<StoreInst>(I) || isa<AtomicCmpXchgInst>(I) ||
 168          isa<AtomicRMWInst>(I) || isa<FenceInst>(I) || isReadWriteMemCall(I);
 169 }