X86: Add prefetch insertion based on Propeller profile

This commit introduces a new pass for prefetch insertion on X86 targets. The pass utilizes Propeller profiles to guide prefetch placement, optimizing memory access patterns. The new file llvm/lib/Target/X86/PrefetchInsertion.cpp implements this functionality. This commit also includes necessary modifications to related CodeGen and X86 target files to integrate the new pass. A build issue where PrefetchInsertion.cpp was not included in the CMakeLists.txt was also resolved.

Author: rlavaee

llvm/include/llvm/CodeGen/BasicBlockSectionsProfileReader.h

@@ -42,6 +42,17 @@ struct BBClusterInfo {
  unsigned PositionInCluster;
 };
 
+struct BBPosition {
+ UniqueBBID BBID;
+ unsigned BBOffset;
+};
+
+struct PrefetchHint {
+ BBPosition SitePosition;
+ StringRef TargetFunctionName;
+ BBPosition TargetPosition;
+};
+
 // This represents the raw input profile for one function.
 struct FunctionPathAndClusterInfo {
  // BB Cluster information specified by `UniqueBBID`s.
@@ -50,21 +61,44 @@ struct FunctionPathAndClusterInfo {
  // the edge a -> b (a is not cloned). The index of the path in this vector
  // determines the `UniqueBBID::CloneID` of the cloned blocks in that path.
  SmallVector<SmallVector<unsigned>> ClonePaths;
+ SmallVector<PrefetchHint> PrefetchHints;
+ DenseSet<BBPosition> PrefetchTargets;
  // Node counts for each basic block.
  DenseMap<UniqueBBID, uint64_t> NodeCounts;
- // Edge counts for each edge, stored as a nested map.
+ // Edge counts for each edge.
  DenseMap<UniqueBBID, DenseMap<UniqueBBID, uint64_t>> EdgeCounts;
  // Hash for each basic block. The Hashes are stored for every original block
  // (not cloned blocks), hence the map key being unsigned instead of
  // UniqueBBID.
  DenseMap<unsigned, uint64_t> BBHashes;
 };
 
+// Provides DenseMapInfo BBPosition.
+template <> struct DenseMapInfo<BBPosition> {
+ static inline BBPosition getEmptyKey() {
+ return {DenseMapInfo<UniqueBBID>::getEmptyKey(),
+ DenseMapInfo<unsigned>::getEmptyKey()};
+ }
+ static inline BBPosition getTombstoneKey() {
+ return BBPosition{DenseMapInfo<UniqueBBID>::getTombstoneKey(),
+ DenseMapInfo<unsigned>::getTombstoneKey()};
+ }
+ static unsigned getHashValue(const BBPosition &Val) {
+ std::pair<unsigned, unsigned> PairVal = std::make_pair(
+ DenseMapInfo<UniqueBBID>::getHashValue(Val.BBID), Val.BBOffset);
+ return DenseMapInfo<std::pair<unsigned, unsigned>>::getHashValue(PairVal);
+ }
+ static bool isEqual(const BBPosition &LHS, const BBPosition &RHS) {
+ return DenseMapInfo<UniqueBBID>::isEqual(LHS.BBID, RHS.BBID) &&
+ DenseMapInfo<unsigned>::isEqual(LHS.BBOffset, RHS.BBOffset);
+ }
+};
+
 class BasicBlockSectionsProfileReader {
 public:
  friend class BasicBlockSectionsProfileReaderWrapperPass;
  BasicBlockSectionsProfileReader(const MemoryBuffer *Buf)
- : MBuf(Buf), LineIt(*Buf, /*SkipBlanks=*/true, /*CommentMarker=*/'#'){};
+ : MBuf(Buf), LineIt(*Buf, /*SkipBlanks=*/true, /*CommentMarker=*/'#') {};
 
  BasicBlockSectionsProfileReader() = default;
 
@@ -90,6 +124,11 @@ class BasicBlockSectionsProfileReader {
  uint64_t getEdgeCount(StringRef FuncName, const UniqueBBID &SrcBBID,
  const UniqueBBID &SinkBBID) const;
 
+ SmallVector<PrefetchHint>
+ getPrefetchHintsForFunction(StringRef FuncName) const;
+
+ DenseSet<BBPosition> getPrefetchTargetsForFunction(StringRef FuncName) const;
+
 private:
  StringRef getAliasName(StringRef FuncName) const {
  auto R = FuncAliasMap.find(FuncName);
@@ -198,6 +237,10 @@ class BasicBlockSectionsProfileReaderWrapperPass : public ImmutablePass {
 
  uint64_t getEdgeCount(StringRef FuncName, const UniqueBBID &SrcBBID,
  const UniqueBBID &DestBBID) const;
+ SmallVector<PrefetchHint>
+ getPrefetchHintsForFunction(StringRef FuncName) const;
+
+ DenseSet<BBPosition> getPrefetchTargetsForFunction(StringRef FuncName) const;
 
  // Initializes the FunctionNameToDIFilename map for the current module and
  // then reads the profile for the matching functions.