[NFC][LiveStacks] Use vectors instead of map and unordred_map

Author: Ralender

llvm/include/llvm/CodeGen/LiveStacks.h

@@ -40,49 +40,43 @@ class LiveStacks {
   ///
   VNInfo::Allocator VNInfoAllocator;
 
-  /// S2IMap - Stack slot indices to live interval mapping.
-  using SS2IntervalMap = std::unordered_map<int, LiveInterval>;
-  SS2IntervalMap S2IMap;
-
-  /// S2RCMap - Stack slot indices to register class mapping.
-  std::map<int, const TargetRegisterClass *> S2RCMap;
+  int StartIdx = -1;
+  SmallVector<LiveInterval *> S2LI;
+  SmallVector<const TargetRegisterClass *> S2RC;
 
 public:
-  using iterator = SS2IntervalMap::iterator;
-  using const_iterator = SS2IntervalMap::const_iterator;
+  using iterator = SmallVector<LiveInterval *>::iterator;
+  using const_iterator = SmallVector<LiveInterval *>::const_iterator;
 
-  const_iterator begin() const { return S2IMap.begin(); }
-  const_iterator end() const { return S2IMap.end(); }
-  iterator begin() { return S2IMap.begin(); }
-  iterator end() { return S2IMap.end(); }
+  const_iterator begin() const { return S2LI.begin(); }
+  const_iterator end() const { return S2LI.end(); }
+  iterator begin() { return S2LI.begin(); }
+  iterator end() { return S2LI.end(); }
 
-  unsigned getNumIntervals() const { return (unsigned)S2IMap.size(); }
+  unsigned getStartIdx() const { return StartIdx; }
+  unsigned getNumIntervals() const { return (unsigned)S2LI.size(); }
 
   LiveInterval &getOrCreateInterval(int Slot, const TargetRegisterClass *RC);
 
   LiveInterval &getInterval(int Slot) {
     assert(Slot >= 0 && "Spill slot indice must be >= 0");
-    SS2IntervalMap::iterator I = S2IMap.find(Slot);
-    assert(I != S2IMap.end() && "Interval does not exist for stack slot");
-    return I->second;
+    return *S2LI[Slot - StartIdx];
   }
 
   const LiveInterval &getInterval(int Slot) const {
     assert(Slot >= 0 && "Spill slot indice must be >= 0");
-    SS2IntervalMap::const_iterator I = S2IMap.find(Slot);
-    assert(I != S2IMap.end() && "Interval does not exist for stack slot");
-    return I->second;
+    return *S2LI[Slot - StartIdx];
   }
 
-  bool hasInterval(int Slot) const { return S2IMap.count(Slot); }
+  bool hasInterval(int Slot) const {
+    if (Slot < StartIdx || StartIdx == -1)
+      return false;
+    return !getInterval(Slot).empty();
+  }
 
   const TargetRegisterClass *getIntervalRegClass(int Slot) const {
     assert(Slot >= 0 && "Spill slot indice must be >= 0");
-    std::map<int, const TargetRegisterClass *>::const_iterator I =
-        S2RCMap.find(Slot);
-    assert(I != S2RCMap.end() &&
-           "Register class info does not exist for stack slot");
-    return I->second;
+    return S2RC[Slot - StartIdx];
   }
 
   VNInfo::Allocator &getVNInfoAllocator() { return VNInfoAllocator; }

llvm/lib/CodeGen/LiveStacks.cpp

@@ -37,10 +37,12 @@ void LiveStacksWrapperLegacy::getAnalysisUsage(AnalysisUsage &AU) const {
 }
 
 void LiveStacks::releaseMemory() {
+  for (int Idx = 0; Idx < (int)S2LI.size(); ++Idx)
+    S2LI[Idx]->~LiveInterval();
   // Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
   VNInfoAllocator.Reset();
-  S2IMap.clear();
-  S2RCMap.clear();
+  S2LI.clear();
+  S2RC.clear();
 }
 
 void LiveStacks::init(MachineFunction &MF) {
@@ -52,20 +54,22 @@ void LiveStacks::init(MachineFunction &MF) {
 LiveInterval &
 LiveStacks::getOrCreateInterval(int Slot, const TargetRegisterClass *RC) {
   assert(Slot >= 0 && "Spill slot indice must be >= 0");
-  SS2IntervalMap::iterator I = S2IMap.find(Slot);
-  if (I == S2IMap.end()) {
-    I = S2IMap
-            .emplace(
-                std::piecewise_construct, std::forward_as_tuple(Slot),
-                std::forward_as_tuple(Register::index2StackSlot(Slot), 0.0F))
-            .first;
-    S2RCMap.insert(std::make_pair(Slot, RC));
+  if (StartIdx == -1)
+    StartIdx = Slot;
+
+  int Idx = Slot - StartIdx;
+  assert(Idx >= 0 && "Slot not in order ?");
+  if (Idx < (int)S2LI.size()) {
+    S2RC[Idx] = TRI->getCommonSubClass(S2RC[Idx], RC);
   } else {
-    // Use the largest common subclass register class.
-    const TargetRegisterClass *&OldRC = S2RCMap[Slot];
-    OldRC = TRI->getCommonSubClass(OldRC, RC);
+    S2RC.resize(Idx + 1);
+    S2LI.resize(Idx + 1);
+    S2LI[Idx] = this->VNInfoAllocator.Allocate<LiveInterval>();
+    new (S2LI[Idx]) LiveInterval(Register::index2StackSlot(Slot), 0.0F);
+    S2RC[Idx] = RC;
   }
-  return I->second;
+  assert(S2RC.size() == S2LI.size());
+  return *S2LI[Idx];
 }
 
 AnalysisKey LiveStacksAnalysis::Key;
@@ -96,13 +100,12 @@ void LiveStacksWrapperLegacy::print(raw_ostream &OS, const Module *) const {
 }
 
 /// print - Implement the dump method.
-void LiveStacks::print(raw_ostream &OS, const Module*) const {
+void LiveStacks::print(raw_ostream &OS, const Module *) const {
 
   OS << "********** INTERVALS **********\n";
-  for (const_iterator I = begin(), E = end(); I != E; ++I) {
-    I->second.print(OS);
-    int Slot = I->first;
-    const TargetRegisterClass *RC = getIntervalRegClass(Slot);
+  for (int Idx = 0; Idx < (int)S2LI.size(); ++Idx) {
+    S2LI[Idx]->print(OS);
+    const TargetRegisterClass *RC = S2RC[Idx];
     if (RC)
       OS << " [" << TRI->getRegClassName(RC) << "]\n";
     else

llvm/lib/CodeGen/StackSlotColoring.cpp

@@ -262,24 +262,14 @@ void StackSlotColoring::InitializeSlots() {
   UsedColors[0].resize(LastFI);
   Assignments.resize(LastFI);
 
-  using Pair = std::iterator_traits<LiveStacks::iterator>::value_type;
-
-  SmallVector<Pair *, 16> Intervals;
-
-  Intervals.reserve(LS->getNumIntervals());
-  for (auto &I : *LS)
-    Intervals.push_back(&I);
-  llvm::sort(Intervals,
-             [](Pair *LHS, Pair *RHS) { return LHS->first < RHS->first; });
-
   // Gather all spill slots into a list.
   LLVM_DEBUG(dbgs() << "Spill slot intervals:\n");
-  for (auto *I : Intervals) {
-    LiveInterval &li = I->second;
-    LLVM_DEBUG(li.dump());
-    int FI = li.reg().stackSlotIndex();
-    if (MFI->isDeadObjectIndex(FI))
+  for (auto [Idx, I] : llvm::enumerate(*LS)) {
+    int FI = Idx + LS->getStartIdx();
+    if (!I || MFI->isDeadObjectIndex(FI))
       continue;
+    LiveInterval &li = *I;
+    LLVM_DEBUG(li.dump());
 
     SSIntervals.push_back(&li);
     OrigAlignments[FI] = MFI->getObjectAlign(FI);

llvm/lib/Target/AMDGPU/AMDGPUMarkLastScratchLoad.cpp

@@ -102,15 +102,15 @@ bool AMDGPUMarkLastScratchLoad::run(MachineFunction &MF) {
 
   bool Changed = false;
 
-  for (auto &[SS, LI] : *LS) {
-    for (const LiveRange::Segment &Segment : LI.segments) {
+  for (auto *LI : *LS) {
+    for (const LiveRange::Segment &Segment : LI->segments) {
 
       // Ignore segments that run to the end of basic block because in this case
       // slot is still live at the end of it.
       if (Segment.end.isBlock())
         continue;
 
-      const int FrameIndex = LI.reg().stackSlotIndex();
+      const int FrameIndex = LI->reg().stackSlotIndex();
       MachineInstr *LastLoad = nullptr;
 
       MachineInstr *MISegmentEnd = SI->getInstructionFromIndex(Segment.end);