Change to using unsigned values for CallsiteIndex

Author: rlavaee

llvm/include/llvm/CodeGen/BasicBlockSectionsProfileReader.h

@@ -42,11 +42,12 @@ struct BBClusterInfo {
   unsigned PositionInCluster;
 };
 
-// The prefetch symbol is emitted immediately after the call of the given index
-// in block `BBID` (or at the beginning of the block if CallsiteIndex is -1).
+// The prefetch symbol is emitted immediately after the call of the given index,
+// in block `BBID` (First call has an index of 1). Zero callsite index means the
+// start of the block.
 struct CallsiteID {
   UniqueBBID BBID;
-  int CallsiteIndex;
+  unsigned CallsiteIndex;
 };
 
 // This represents the raw input profile for one function.

llvm/include/llvm/CodeGen/MachineBasicBlock.h

@@ -230,9 +230,10 @@ class MachineBasicBlock
   mutable MCSymbol *CachedMCSymbol = nullptr;
 
   /// Contains the callsite indices in this block that are targets of code
-  /// prefetching. The index `i` specifies the `i`th call, with `-1`
-  /// representing the beginning of the block.
-  SmallVector<int> PrefetchTargetCallsiteIndexes;
+  /// prefetching. The index `i` specifies the `i`th call, with zero
+  /// representing the beginning of the block and ` representing the first call.
+  /// Must be in ascending order and without duplicates.
+  SmallVector<unsigned> PrefetchTargetCallsiteIndexes;
 
   /// Cached MCSymbol for this block (used if IsEHContTarget).
   mutable MCSymbol *CachedEHContMCSymbol = nullptr;
@@ -715,11 +716,11 @@ class MachineBasicBlock
 
   std::optional<UniqueBBID> getBBID() const { return BBID; }
 
-  const SmallVector<int> &getPrefetchTargetCallsiteIndexes() const {
+  const SmallVector<unsigned> &getPrefetchTargetCallsiteIndexes() const {
     return PrefetchTargetCallsiteIndexes;
   }
 
-  void setPrefetchTargetCallsiteIndexes(const SmallVector<int> &V) {
+  void setPrefetchTargetCallsiteIndexes(const SmallVector<unsigned> &V) {
     PrefetchTargetCallsiteIndexes = V;
   }
 

llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -1986,14 +1986,14 @@ void AsmPrinter::emitFunctionBody() {
     emitBasicBlockStart(MBB);
     DenseMap<StringRef, unsigned> MnemonicCounts;
 
-    SmallVector<int> PrefetchTargets = MBB.getPrefetchTargetCallsiteIndexes();
+    SmallVector<unsigned> PrefetchTargets = MBB.getPrefetchTargetCallsiteIndexes();
     auto PrefetchTargetIt = PrefetchTargets.begin();
-    int CurrentCallsiteIndex = -1;
+    unsigned LastCallsiteIndex = 0;
     // Helper to emit a symbol for the prefetch target and proceed to the next
     // one.
     auto EmitPrefetchTargetSymbolIfNeeded = [&]() {
       if (PrefetchTargetIt != PrefetchTargets.end() &&
-          *PrefetchTargetIt == CurrentCallsiteIndex) {
+          *PrefetchTargetIt == LastCallsiteIndex) {
         MCSymbol *PrefetchTargetSymbol = OutContext.getOrCreateSymbol(
             Twine("__llvm_prefetch_target_") + MF->getName() + Twine("_") +
             utostr(MBB.getBBID()->BaseID) + Twine("_") +
@@ -2151,7 +2151,7 @@ void AsmPrinter::emitFunctionBody() {
       if (MI.isCall()) {
         if (MF->getTarget().Options.BBAddrMap)
           OutStreamer->emitLabel(createCallsiteEndSymbol(MBB));
-        CurrentCallsiteIndex++;
+        LastCallsiteIndex++;
       }
 
       if (TM.Options.EmitCallGraphSection && MI.isCall())

llvm/lib/CodeGen/BasicBlockSectionsProfileReader.cpp

@@ -358,12 +358,12 @@ Error BasicBlockSectionsProfileReader::ReadV1Profile() {
       auto TargetBBID = parseUniqueBBID(PrefetchTargetStr[0]);
       if (!TargetBBID)
         return TargetBBID.takeError();
-      long long CallsiteIndex;
-      if (getAsSignedInteger(PrefetchTargetStr[1], 10, CallsiteIndex))
+      unsigned long long CallsiteIndex;
+      if (getAsUnsignedInteger(PrefetchTargetStr[1], 10, CallsiteIndex))
         return createProfileParseError(Twine("signed integer expected: '") +
                                        PrefetchTargetStr[1]);
       FI->second.PrefetchTargets.push_back(
-          CallsiteID{*TargetBBID, static_cast<int>(CallsiteIndex - 1)});
+          CallsiteID{*TargetBBID, static_cast<unsigned>(CallsiteIndex)});
       continue;
     }
     default:

llvm/lib/CodeGen/InsertCodePrefetch.cpp

@@ -73,9 +73,14 @@ bool InsertCodePrefetch::runOnMachineFunction(MachineFunction &MF) {
   SmallVector<CallsiteID> PrefetchTargets =
       getAnalysis<BasicBlockSectionsProfileReaderWrapperPass>()
           .getPrefetchTargetsForFunction(MF.getName());
-  DenseMap<UniqueBBID, SmallVector<int>> PrefetchTargetsByBBID;
+  DenseMap<UniqueBBID, SmallVector<unsigned>> PrefetchTargetsByBBID;
   for (const auto &Target : PrefetchTargets)
     PrefetchTargetsByBBID[Target.BBID].push_back(Target.CallsiteIndex);
+  // Sort and uniquify the callsite indices for every block.
+  for (auto &[K, V]: PrefetchTargetsByBBID) {
+    llvm::sort(V);
+    V.erase(llvm::unique(V), V.end());
+  }
   for (auto &MBB : MF) {
     auto R = PrefetchTargetsByBBID.find(*MBB.getBBID());
     if (R == PrefetchTargetsByBBID.end())