[MachineScheduler] Add support for store clustering

[junbuml]

Summary

Perform store clustering just like load clustering. This change add
StoreClusterMutation in machine-scheduler. To control StoreClusterMutation,
added enableClusterStores() in TargetInstrInfo.h. This is enabled only on AArch64
for now.

This change also add support for unscaled stores which were not handled in getMemOpBaseRegImmOfs().

[MatzeB]

Looks like an obvious change to me. It is so obvious that I wonder why it wasn't added in the first place, maybe there is a reason to it?

include/llvm/Target/TargetInstrInfo.h

981–989

Would it make sense to simply rename "xxxClusterLoads" to "xxxClusterMemOps" instead of adding an extra interface? The target can still control whether loads or stores are clustered in getMemOpBaseRegImmOfs().

The same is true for a lot of the following code which would need the differentiation between loads and stores anymore.

[junbuml]

include/llvm/Target/TargetInstrInfo.h

981–989

I agree of using MemOps, instead of using load/store mixed.

Removing enableClusterStores() means that we enable this StoreMutation by default in other targets if getMemOpBaseRegImmOfs already support stores. We should extend reviewers and tests in other targets. As of now, I can see enableClusterLoads() is also enabled in :

AMDGPUInstrInfo.cpp.

[junbuml]

I compared llvm stats with/without this change for Spec2006. Overall, this patch increases the number of ld/st pairs by about 3% for Spec2006. I didn't see any serious regression in other statistics (see below).

Please see the full summary of llvm stats diff collected for spec2006 without and with this patch. For example, the third stat indicates 1495 (or ~3%) more ld/st pairs are generated with this patch :

    2 (0.06%) aarch64-copyelim - Number of copies removed.                        
   38 (0.81%) aarch64-ldst-opt - Number of load/store from unscaled generated     
 1495 (3.00%) aarch64-ldst-opt - Number of load/store pair instructions generated 
   28 (1.14%) aarch64-ldst-opt - Number of post-index updates folded              
-1661 (-0.06%) asm-printer - Number of machine instrs printed                      
-6056 (-0.01%) assembler - Number of emitted object file bytes                     
   67 (0.01%) assembler - Number of evaluated fixups                              
  -42 (-0.13%) branchfolding - Number of block tails merged                        
    3 (0.00%) branchfolding - Number of branches optimized                        
  -32 (-0.055%) branchfolding - Number of dead blocks removed                       
   -7 (-0.69%) branchfolding - Number of times common instructions are hoisted     
    2 (0.02%) codegen-cp - Number of dead copies deleted                          
    3 (1.69%) machine-licm - Number of machine instructions hoisted out of loops post regalloc
   67 (0.01%) mccodeemitter - Number of MC fixups created.                        
-1661 (-0.06%) mccodeemitter - Number of MC instructions emitted.                  
   93 (0.00%) mcexpr - Number of MCExpr evaluations                               
  112 (0.00%) pei - Number of bytes used for stack in all functions               
 -491 (-0.54%) regalloc - Number of copies inserted for splitting                  
   15 (0.19%) regalloc - Number of hoisted spills                                 
 -103 (-0.03%) regalloc - Number of identity moves eliminated after rewriting      
    5 (0.02%) regalloc - Number of interferences evicted                          
   -2 (-0.23%) regalloc - Number of live ranges fractured by DCE                   
 -127 (-0.07%) regalloc - Number of new live ranges queued                         
   -7 (-0.58%) regalloc - Number of omitted spills of reloads                      
 -128 (-0.01%) regalloc - Number of registers assigned                             
  -21 (-0.05%) regalloc - Number of registers unassigned                           
   46 (0.12%) regalloc - Number of reloads inserted                               
   -3 (-0.41%) regalloc - Number of reloads removed                                
   -2 (-0.01%) regalloc - Number of rematerialized defs for spilling               
   -6 (-0.02%) regalloc - Number of spilled live ranges                            
   -7 (-1.23%) regalloc - Number of spilled snippets                               
  -31 (-0.13%) regalloc - Number of spills inserted                                
   -3 (-0.07%) regalloc - Number of spills removed                                 
   -5 (-0.04%) regalloc - Number of split global live ranges                       
   -5 (-0.03%) regalloc - Number of splits finished                                
   -3 (-0.02%) regalloc - Number of splits that were simple                        
  264 (0.61%) slotindexes - Number of local renumberings                          
   -2 (-0.07%) stackslotcoloring - Number of stack slots eliminated due to coloring
  -13 (-0.00%) tailduplication - Additional instructions due to tail duplication   
   -7 (-0.29%) tailduplication - Number of dead blocks removed                     
    3 (0.05%) tailduplication - Number of tail duplicated blocks                  
   -5 (-0.13%) tailduplication - Number of tails duplicated

[flyingforyou]

I also think this is reasonable change.

lib/CodeGen/MachineScheduler.cpp

1380

IsLoad?

[junbuml]

Addressed comments from comment Mattias and Junmo.

[mcrosier]

LGTM under the assumption this does not change codegen for the AMDGPU targets.

[junbuml]

Just minor renaming and clean up.

[junbuml]

As enableClusterMemOps() returns true in AMDGPUInstrInfo.cpp, I still want to wait until this patch is reviewed by reviewers from AMDGPU.

[junbuml]

Kindly ping.
We need to confirm if this change doesn't have any negative impact on AMDGPU. Or, I can enable this only on AArch64 by adding enableClusterStores() in TargetInstrInfo.h.

[junbuml]

Enabled this only on AArch64 for now by adding enableClusterStores().

Tom,
I believe you can easily enable this for AMDGPU later with proper tests as a separate patch.

[junbuml]

Ping..
Please let me know if this is still LGTM.

[atrick]

This is fine with me.

If there was some reason I didn't do this it was specific to the microarchitecture and downstream optimizations at that time. As long as we get good results from this change I have no objection.

[mcrosier]

In D18376#399964, @atrick wrote:

This is fine with me.

If there was some reason I didn't do this it was specific to the microarchitecture and downstream optimizations at that time. As long as we get good results from this change I have no objection.

Thanks, Andy.

I think the last bit that is needed is for @arsenm or @tstellarAMD to approve the patch as this may impact the AMD target.

[junbuml]

Please note that in my last change, I turned it on only in AArch64 by separating enableClusterStores() and enableClusterLoads(). enableClusterStores() is off in AMD by default.

[mcrosier]

In D18376#400164, @junbuml wrote:

Please note that in my last change, I turned it on only in AArch64 by separating enableClusterStores() and enableClusterLoads(). enableClusterStores() is off in AMD by default.

In that case I think this is fine to commit. Thanks, Jun.

[junbuml]

In D18376#399964, @atrick wrote:
This is fine with me.

If there was some reason I didn't do this it was specific to the microarchitecture and downstream optimizations at that time. As >long as we get good results from this change I have no objection.

I didn't see clear performance gains in score with this change in my spec2006 test. However, with this change I observed overall better llvm stats; please see my previous comments showing differences of llvm stats for spec2006.

I'm going to commit this if there is any objection by tomorrow.

[junbuml]

Landed in r266437.
Thanks for the reviews !

include/llvm/Target/TargetInstrInfo.h

public:
   /// Get the base register and byte offset of an instruction that reads/writes
   /// memory.
   virtual bool getMemOpBaseRegImmOfs(MachineInstr *MemOp, unsigned &BaseReg,
                                      int64_t &Offset,
                                      const TargetRegisterInfo *TRI) const {
     return false;
   }
 
   virtual bool enableClusterLoads() const { return false; }
 
+  virtual bool enableClusterStores() const { return false; }
+
   virtual bool shouldClusterLoads(MachineInstr *FirstLdSt,
                                   MachineInstr *SecondLdSt,
                                   unsigned NumLoads) const {
     return false;
   }
 
   /// Can this target fuse the given instructions if they are scheduled
   /// adjacent.
   virtual bool shouldScheduleAdjacent(MachineInstr* First,
                                       MachineInstr *Second) const {
     return false;
   }
 

lib/CodeGen/MachineScheduler.cpp

 #endif // NDEBUG
 
 static cl::opt<bool> EnableRegPressure("misched-regpressure", cl::Hidden,
   cl::desc("Enable register pressure scheduling."), cl::init(true));
 
 static cl::opt<bool> EnableCyclicPath("misched-cyclicpath", cl::Hidden,
   cl::desc("Enable cyclic critical path analysis."), cl::init(true));
 
-static cl::opt<bool> EnableLoadCluster("misched-cluster", cl::Hidden,
-  cl::desc("Enable load clustering."), cl::init(true));
+static cl::opt<bool> EnableLoadCluster("misched-cluster-load", cl::Hidden,
+                                       cl::desc("Enable load clustering."),
+                                       cl::init(true));
+
+static cl::opt<bool> EnableStoreCluster("misched-cluster-store", cl::Hidden,
+                                        cl::desc("Enable store clustering."),
+                                        cl::init(true));
 
 // Experimental heuristics
 static cl::opt<bool> EnableMacroFusion("misched-fusion", cl::Hidden,
   cl::desc("Enable scheduling for macro fusion."), cl::init(true));
 
 static cl::opt<bool> VerifyScheduling("verify-misched", cl::Hidden,
   cl::desc("Verify machine instrs before and after machine scheduling"));
 
if (ShouldTrackPressure) {
 
       updateScheduledPressure(SU, BotRPTracker.getPressure().MaxSetPressure);
       updatePressureDiffs(LiveUses);
     }
   }
 }
 
 //===----------------------------------------------------------------------===//
-// LoadClusterMutation - DAG post-processing to cluster loads.
+// BaseLdStClusterMutation - DAG post-processing to cluster loads or stores.
 //===----------------------------------------------------------------------===//
 
 namespace {
 /// \brief Post-process the DAG to create cluster edges between neighboring
-/// loads.
-class LoadClusterMutation : public ScheduleDAGMutation {
-  struct LoadInfo {
+/// loads or between neighboring stores.
+class BaseLdStClusterMutation : public ScheduleDAGMutation {
+  struct LoadStoreInfo {
     SUnit *SU;
     unsigned BaseReg;
     int64_t Offset;
-    LoadInfo(SUnit *su, unsigned reg, int64_t ofs)
+    LoadStoreInfo(SUnit *su, unsigned reg, int64_t ofs)
         : SU(su), BaseReg(reg), Offset(ofs) {}
 
-    bool operator<(const LoadInfo &RHS) const {
+    bool operator<(const LoadStoreInfo &RHS) const {
       return std::tie(BaseReg, Offset) < std::tie(RHS.BaseReg, RHS.Offset);
     }
   };
 
   const TargetInstrInfo *TII;
   const TargetRegisterInfo *TRI;
+  bool isLoad;
+
 public:
-  LoadClusterMutation(const TargetInstrInfo *tii,
-                      const TargetRegisterInfo *tri)
-    : TII(tii), TRI(tri) {}
+  BaseLdStClusterMutation(const TargetInstrInfo *tii,
+                          const TargetRegisterInfo *tri, bool isLoad)
+      : TII(tii), TRI(tri), isLoad(isLoad) {}
 
   void apply(ScheduleDAGInstrs *DAGInstrs) override;
+
 protected:
-  void clusterNeighboringLoads(ArrayRef<SUnit*> Loads, ScheduleDAGMI *DAG);
+  void clusterNeighboringLdSt(ArrayRef<SUnit *> MemOps, ScheduleDAGMI *DAG);
+};
+
+class StoreClusterMutation : public BaseLdStClusterMutation {
+public:
+  StoreClusterMutation(const TargetInstrInfo *tii,
+                       const TargetRegisterInfo *tri)
+      : BaseLdStClusterMutation(tii, tri, false) {}
+};
+
+class LoadClusterMutation : public BaseLdStClusterMutation {
+public:
+  LoadClusterMutation(const TargetInstrInfo *tii, const TargetRegisterInfo *tri)
+      : BaseLdStClusterMutation(tii, tri, true) {}
 };
 } // anonymous
 
-void LoadClusterMutation::clusterNeighboringLoads(ArrayRef<SUnit*> Loads,
+void BaseLdStClusterMutation::clusterNeighboringLdSt(ArrayRef<SUnit *> MemOps,
                                                      ScheduleDAGMI *DAG) {
-  SmallVector<LoadClusterMutation::LoadInfo,32> LoadRecords;
-  for (unsigned Idx = 0, End = Loads.size(); Idx != End; ++Idx) {
-    SUnit *SU = Loads[Idx];
+  SmallVector<BaseLdStClusterMutation::LoadStoreInfo, 32> LdStRecords;
+  for (unsigned Idx = 0, End = MemOps.size(); Idx != End; ++Idx) {
+    SUnit *SU = MemOps[Idx];
     unsigned BaseReg;
     int64_t Offset;
     if (TII->getMemOpBaseRegImmOfs(SU->getInstr(), BaseReg, Offset, TRI))
-      LoadRecords.push_back(LoadInfo(SU, BaseReg, Offset));
+      LdStRecords.push_back(LoadStoreInfo(SU, BaseReg, Offset));
   }
-  if (LoadRecords.size() < 2)
+  if (LdStRecords.size() < 2)
     return;
-  std::sort(LoadRecords.begin(), LoadRecords.end());
+
+  std::sort(LdStRecords.begin(), LdStRecords.end());
   unsigned ClusterLength = 1;
-  for (unsigned Idx = 0, End = LoadRecords.size(); Idx < (End - 1); ++Idx) {
-    if (LoadRecords[Idx].BaseReg != LoadRecords[Idx+1].BaseReg) {
+  for (unsigned Idx = 0, End = LdStRecords.size(); Idx < (End - 1); ++Idx) {
+    if (LdStRecords[Idx].BaseReg != LdStRecords[Idx+1].BaseReg) {
       ClusterLength = 1;
       continue;
     }
 
-    SUnit *SUa = LoadRecords[Idx].SU;
-    SUnit *SUb = LoadRecords[Idx+1].SU;
+
+    SUnit *SUa = LdStRecords[Idx].SU;
+    SUnit *SUb = LdStRecords[Idx+1].SU;
     if (TII->shouldClusterLoads(SUa->getInstr(), SUb->getInstr(), ClusterLength)
         && DAG->addEdge(SUb, SDep(SUa, SDep::Cluster))) {
-
-      DEBUG(dbgs() << "Cluster loads SU(" << SUa->NodeNum << ") - SU("
+      DEBUG(dbgs() << "Cluster ld/st SU(" << SUa->NodeNum << ") - SU("
             << SUb->NodeNum << ")\n");
       // Copy successor edges from SUa to SUb. Interleaving computation
       // dependent on SUa can prevent load combining due to register reuse.
       // Predecessor edges do not need to be copied from SUb to SUa since nearby
       // loads should have effectively the same inputs.
       for (SUnit::const_succ_iterator
              SI = SUa->Succs.begin(), SE = SUa->Succs.end(); SI != SE; ++SI) {
         if (SI->getSUnit() == SUb)
           continue;
         DEBUG(dbgs() << "  Copy Succ SU(" << SI->getSUnit()->NodeNum << ")\n");
         DAG->addEdge(SI->getSUnit(), SDep(SUb, SDep::Artificial));
       }
       ++ClusterLength;
     }
     else
       ClusterLength = 1;
   }
 }
 
 /// \brief Callback from DAG postProcessing to create cluster edges for loads.
-void LoadClusterMutation::apply(ScheduleDAGInstrs *DAGInstrs) {
+void BaseLdStClusterMutation::apply(ScheduleDAGInstrs *DAGInstrs) {
+
   ScheduleDAGMI *DAG = static_cast<ScheduleDAGMI*>(DAGInstrs);
 
   // Map DAG NodeNum to store chain ID.
   DenseMap<unsigned, unsigned> StoreChainIDs;
   // Map each store chain to a set of dependent loads.
   SmallVector<SmallVector<SUnit*,4>, 32> StoreChainDependents;
   for (unsigned Idx = 0, End = DAG->SUnits.size(); Idx != End; ++Idx) {
     SUnit *SU = &DAG->SUnits[Idx];
-    if (!SU->getInstr()->mayLoad())
+    if ((isLoad && !SU->getInstr()->mayLoad()) ||
+        (!isLoad && !SU->getInstr()->mayStore()))
       continue;
+
     unsigned ChainPredID = DAG->SUnits.size();
     for (SUnit::const_pred_iterator
            PI = SU->Preds.begin(), PE = SU->Preds.end(); PI != PE; ++PI) {
       if (PI->isCtrl()) {
         ChainPredID = PI->getSUnit()->NodeNum;
         break;
       }
     }
     // Check if this chain-like pred has been seen
     // before. ChainPredID==MaxNodeID for loads at the top of the schedule.
     unsigned NumChains = StoreChainDependents.size();
     std::pair<DenseMap<unsigned, unsigned>::iterator, bool> Result =
       StoreChainIDs.insert(std::make_pair(ChainPredID, NumChains));
     if (Result.second)
       StoreChainDependents.resize(NumChains + 1);
     StoreChainDependents[Result.first->second].push_back(SU);
   }
+
   // Iterate over the store chains.
   for (unsigned Idx = 0, End = StoreChainDependents.size(); Idx != End; ++Idx)
-    clusterNeighboringLoads(StoreChainDependents[Idx], DAG);
+    clusterNeighboringLdSt(StoreChainDependents[Idx], DAG);
 }
 
 //===----------------------------------------------------------------------===//
 // MacroFusion - DAG post-processing to encourage fusion of macro ops.
 //===----------------------------------------------------------------------===//
 
 namespace {
 /// \brief Post-process the DAG to create cluster edges between instructions

 static ScheduleDAGInstrs *createGenericSchedLive(MachineSchedContext *C) {
   ScheduleDAGMILive *DAG = new ScheduleDAGMILive(C, make_unique<GenericScheduler>(C));
   // Register DAG post-processors.
   //
   // FIXME: extend the mutation API to allow earlier mutations to instantiate
   // data and pass it to later mutations. Have a single mutation that gathers
   // the interesting nodes in one pass.
   DAG->addMutation(make_unique<CopyConstrain>(DAG->TII, DAG->TRI));
+
   if (EnableLoadCluster && DAG->TII->enableClusterLoads())
     DAG->addMutation(make_unique<LoadClusterMutation>(DAG->TII, DAG->TRI));
+
+  if (EnableStoreCluster && DAG->TII->enableClusterStores())
+    DAG->addMutation(make_unique<StoreClusterMutation>(DAG->TII, DAG->TRI));
+
   if (EnableMacroFusion)
     DAG->addMutation(make_unique<MacroFusion>(*DAG->TII, *DAG->TRI));
   return DAG;
 }
 
 static MachineSchedRegistry
 GenericSchedRegistry("converge", "Standard converging scheduler.",
                      createGenericSchedLive);

lib/Target/AArch64/AArch64InstrInfo.h

bool getMemOpBaseRegImmOfs(MachineInstr *LdSt, unsigned &BaseReg,
                              const TargetRegisterInfo *TRI) const override;
 
   bool getMemOpBaseRegImmOfsWidth(MachineInstr *LdSt, unsigned &BaseReg,
                                   int64_t &Offset, unsigned &Width,
                                   const TargetRegisterInfo *TRI) const;
 
   bool enableClusterLoads() const override { return true; }
 
+  bool enableClusterStores() const override { return true; }
+
   bool shouldClusterLoads(MachineInstr *FirstLdSt, MachineInstr *SecondLdSt,
                           unsigned NumLoads) const override;
 
   bool shouldScheduleAdjacent(MachineInstr *First,
                               MachineInstr *Second) const override;
 
   MachineInstr *emitFrameIndexDebugValue(MachineFunction &MF, int FrameIx,
                                          uint64_t Offset, const MDNode *Var,

lib/Target/AArch64/AArch64InstrInfo.cpp

bool AArch64InstrInfo::getMemOpBaseRegImmOfs(
   case AArch64::STRWui:
   case AArch64::LDRSui:
   case AArch64::LDRDui:
   case AArch64::LDRQui:
   case AArch64::LDRXui:
   case AArch64::LDRWui:
   case AArch64::LDRSWui:
   // Unscaled instructions.
+  case AArch64::STURSi:
+  case AArch64::STURDi:
+  case AArch64::STURQi:
+  case AArch64::STURXi:
+  case AArch64::STURWi:
   case AArch64::LDURSi:
   case AArch64::LDURDi:
   case AArch64::LDURQi:
   case AArch64::LDURWi:
   case AArch64::LDURXi:
   case AArch64::LDURSWi:
     unsigned Width;
     return getMemOpBaseRegImmOfsWidth(LdSt, BaseReg, Offset, Width, TRI);

 // Scale the unscaled offsets.  Returns false if the unscaled offset can't be
 // scaled.
 static bool scaleOffset(unsigned Opc, int64_t &Offset) {
   unsigned OffsetStride = 1;
   switch (Opc) {
   default:
     return false;
   case AArch64::LDURQi:
+  case AArch64::STURQi:
     OffsetStride = 16;
     break;
   case AArch64::LDURXi:
   case AArch64::LDURDi:
+  case AArch64::STURXi:
+  case AArch64::STURDi:
     OffsetStride = 8;
     break;
   case AArch64::LDURWi:
   case AArch64::LDURSi:
   case AArch64::LDURSWi:
+  case AArch64::STURWi:
+  case AArch64::STURSi:
     OffsetStride = 4;
     break;
   }
   // If the byte-offset isn't a multiple of the stride, we can't scale this
   // offset.
   if (Offset % OffsetStride != 0)
     return false;
 

test/CodeGen/AArch64/aarch64-stp-cluster.ll

+; REQUIRES: asserts
+; RUN: llc < %s -mtriple=arm64-linux-gnu -mcpu=cortex-a57 -verify-misched -debug-only=misched -aarch64-stp-suppress=false -o - 2>&1 > /dev/null | FileCheck %s
+
+; CHECK: ********** MI Scheduling **********
+; CHECK-LABEL: stp_i64_scale:BB#0
+; CHECK:Cluster ld/st SU(4) - SU(3)
+; CHECK:Cluster ld/st SU(2) - SU(5)
+; CHECK:SU(4):   STRXui %vreg1, %vreg0, 1
+; CHECK:SU(3):   STRXui %vreg1, %vreg0, 2
+; CHECK:SU(2):   STRXui %vreg1, %vreg0, 3
+; CHECK:SU(5):   STRXui %vreg1, %vreg0, 4
+define i64 @stp_i64_scale(i64* nocapture %P, i64 %v) {
+entry:
+  %arrayidx = getelementptr inbounds i64, i64* %P, i64 3
+  store i64 %v, i64* %arrayidx
+  %arrayidx1 = getelementptr inbounds i64, i64* %P, i64 2
+  store i64 %v, i64* %arrayidx1
+  %arrayidx2 = getelementptr inbounds i64, i64* %P, i64 1
+  store i64 %v, i64* %arrayidx2
+  %arrayidx3 = getelementptr inbounds i64, i64* %P, i64 4
+  store i64 %v, i64* %arrayidx3
+  ret i64 %v
+}
+
+; CHECK: ********** MI Scheduling **********
+; CHECK-LABEL: stp_i32_scale:BB#0
+; CHECK:Cluster ld/st SU(4) - SU(3)
+; CHECK:Cluster ld/st SU(2) - SU(5)
+; CHECK:SU(4):   STRWui %vreg1, %vreg0, 1
+; CHECK:SU(3):   STRWui %vreg1, %vreg0, 2
+; CHECK:SU(2):   STRWui %vreg1, %vreg0, 3
+; CHECK:SU(5):   STRWui %vreg1, %vreg0, 4
+define i32 @stp_i32_scale(i32* nocapture %P, i32 %v) {
+entry:
+  %arrayidx = getelementptr inbounds i32, i32* %P, i32 3
+  store i32 %v, i32* %arrayidx
+  %arrayidx1 = getelementptr inbounds i32, i32* %P, i32 2
+  store i32 %v, i32* %arrayidx1
+  %arrayidx2 = getelementptr inbounds i32, i32* %P, i32 1
+  store i32 %v, i32* %arrayidx2
+  %arrayidx3 = getelementptr inbounds i32, i32* %P, i32 4
+  store i32 %v, i32* %arrayidx3
+  ret i32 %v
+}
+
+; CHECK:********** MI Scheduling **********
+; CHECK-LABEL:stp_i64_unscale:BB#0 entry
+; CHECK:Cluster ld/st SU(5) - SU(2)
+; CHECK:Cluster ld/st SU(4) - SU(3)
+; CHECK:SU(5):   STURXi %vreg1, %vreg0, -32
+; CHECK:SU(2):   STURXi %vreg1, %vreg0, -24
+; CHECK:SU(4):   STURXi %vreg1, %vreg0, -16
+; CHECK:SU(3):   STURXi %vreg1, %vreg0, -8
+define void @stp_i64_unscale(i64* nocapture %P, i64 %v) #0 {
+entry:
+  %arrayidx = getelementptr inbounds i64, i64* %P, i64 -3
+  store i64 %v, i64* %arrayidx
+  %arrayidx1 = getelementptr inbounds i64, i64* %P, i64 -1
+  store i64 %v, i64* %arrayidx1
+  %arrayidx2 = getelementptr inbounds i64, i64* %P, i64 -2
+  store i64 %v, i64* %arrayidx2
+  %arrayidx3 = getelementptr inbounds i64, i64* %P, i64 -4
+  store i64 %v, i64* %arrayidx3
+  ret void
+}
+
+; CHECK:********** MI Scheduling **********
+; CHECK-LABEL:stp_i32_unscale:BB#0 entry
+; CHECK:Cluster ld/st SU(5) - SU(2)
+; CHECK:Cluster ld/st SU(4) - SU(3)
+; CHECK:SU(5):   STURWi %vreg1, %vreg0, -16
+; CHECK:SU(2):   STURWi %vreg1, %vreg0, -12
+; CHECK:SU(4):   STURWi %vreg1, %vreg0, -8
+; CHECK:SU(3):   STURWi %vreg1, %vreg0, -4
+define void @stp_i32_unscale(i32* nocapture %P, i32 %v) #0 {
+entry:
+  %arrayidx = getelementptr inbounds i32, i32* %P, i32 -3
+  store i32 %v, i32* %arrayidx
+  %arrayidx1 = getelementptr inbounds i32, i32* %P, i32 -1
+  store i32 %v, i32* %arrayidx1
+  %arrayidx2 = getelementptr inbounds i32, i32* %P, i32 -2
+  store i32 %v, i32* %arrayidx2
+  %arrayidx3 = getelementptr inbounds i32, i32* %P, i32 -4
+  store i32 %v, i32* %arrayidx3
+  ret void
+}
+
+; CHECK:********** MI Scheduling **********
+; CHECK-LABEL:stp_double:BB#0
+; CHECK:Cluster ld/st SU(3) - SU(4)
+; CHECK:Cluster ld/st SU(2) - SU(5)
+; CHECK:SU(3):   STRDui %vreg1, %vreg0, 1
+; CHECK:SU(4):   STRDui %vreg1, %vreg0, 2
+; CHECK:SU(2):   STRDui %vreg1, %vreg0, 3
+; CHECK:SU(5):   STRDui %vreg1, %vreg0, 4
+define void @stp_double(double* nocapture %P, double %v)  {
+entry:
+  %arrayidx = getelementptr inbounds double, double* %P, i64 3
+  store double %v, double* %arrayidx
+  %arrayidx1 = getelementptr inbounds double, double* %P, i64 1
+  store double %v, double* %arrayidx1
+  %arrayidx2 = getelementptr inbounds double, double* %P, i64 2
+  store double %v, double* %arrayidx2
+  %arrayidx3 = getelementptr inbounds double, double* %P, i64 4
+  store double %v, double* %arrayidx3
+  ret void
+}
+
+; CHECK:********** MI Scheduling **********
+; CHECK-LABEL:stp_float:BB#0
+; CHECK:Cluster ld/st SU(3) - SU(4)
+; CHECK:Cluster ld/st SU(2) - SU(5)
+; CHECK:SU(3):   STRSui %vreg1, %vreg0, 1
+; CHECK:SU(4):   STRSui %vreg1, %vreg0, 2
+; CHECK:SU(2):   STRSui %vreg1, %vreg0, 3
+; CHECK:SU(5):   STRSui %vreg1, %vreg0, 4
+define void @stp_float(float* nocapture %P, float %v)  {
+entry:
+  %arrayidx = getelementptr inbounds float, float* %P, i64 3
+  store float %v, float* %arrayidx
+  %arrayidx1 = getelementptr inbounds float, float* %P, i64 1
+  store float %v, float* %arrayidx1
+  %arrayidx2 = getelementptr inbounds float, float* %P, i64 2
+  store float %v, float* %arrayidx2
+  %arrayidx3 = getelementptr inbounds float, float* %P, i64 4
+  store float %v, float* %arrayidx3
+  ret void
+}
+
+; CHECK: ********** MI Scheduling **********
+; CHECK-LABEL: stp_volatile:BB#0
+; CHECK-NOT: Cluster ld/st
+; CHECK:SU(2):   STRXui %vreg1, %vreg0, 3; mem:Volatile
+; CHECK:SU(3):   STRXui %vreg1, %vreg0, 2; mem:Volatile
+; CHECK:SU(4):   STRXui %vreg1, %vreg0, 1; mem:Volatile
+; CHECK:SU(5):   STRXui %vreg1, %vreg0, 4; mem:Volatile
+define i64 @stp_volatile(i64* nocapture %P, i64 %v) {
+entry:
+  %arrayidx = getelementptr inbounds i64, i64* %P, i64 3
+  store volatile i64 %v, i64* %arrayidx
+  %arrayidx1 = getelementptr inbounds i64, i64* %P, i64 2
+  store volatile i64 %v, i64* %arrayidx1
+  %arrayidx2 = getelementptr inbounds i64, i64* %P, i64 1
+  store volatile i64 %v, i64* %arrayidx2
+  %arrayidx3 = getelementptr inbounds i64, i64* %P, i64 4
+  store volatile i64 %v, i64* %arrayidx3
+  ret i64 %v
+}
+

test/CodeGen/AArch64/arm64-ldp-cluster.ll

 ; REQUIRES: asserts
 ; RUN: llc < %s -mtriple=arm64-linux-gnu -mcpu=cortex-a57 -verify-misched -debug-only=misched -o - 2>&1 > /dev/null | FileCheck %s
 
 ; Test ldr clustering.
 ; CHECK: ********** MI Scheduling **********
 ; CHECK-LABEL: ldr_int:BB#0
-; CHECK: Cluster loads SU(1) - SU(2)
+; CHECK: Cluster ld/st SU(1) - SU(2)
 ; CHECK: SU(1):   %vreg{{[0-9]+}}<def> = LDRWui
 ; CHECK: SU(2):   %vreg{{[0-9]+}}<def> = LDRWui
 define i32 @ldr_int(i32* %a) nounwind {
   %p1 = getelementptr inbounds i32, i32* %a, i32 1
   %tmp1 = load i32, i32* %p1, align 2
   %p2 = getelementptr inbounds i32, i32* %a, i32 2
   %tmp2 = load i32, i32* %p2, align 2
   %tmp3 = add i32 %tmp1, %tmp2
   ret i32 %tmp3
 }
 
 ; Test ldpsw clustering
 ; CHECK: ********** MI Scheduling **********
 ; CHECK-LABEL: ldp_sext_int:BB#0
-; CHECK: Cluster loads SU(1) - SU(2)
+; CHECK: Cluster ld/st SU(1) - SU(2)
 ; CHECK: SU(1):   %vreg{{[0-9]+}}<def> = LDRSWui
 ; CHECK: SU(2):   %vreg{{[0-9]+}}<def> = LDRSWui
 define i64 @ldp_sext_int(i32* %p) nounwind {
   %tmp = load i32, i32* %p, align 4
   %add.ptr = getelementptr inbounds i32, i32* %p, i64 1
   %tmp1 = load i32, i32* %add.ptr, align 4
   %sexttmp = sext i32 %tmp to i64
   %sexttmp1 = sext i32 %tmp1 to i64
   %add = add nsw i64 %sexttmp1, %sexttmp
   ret i64 %add
 }
 
 ; Test ldur clustering.
 ; CHECK: ********** MI Scheduling **********
 ; CHECK-LABEL: ldur_int:BB#0
-; CHECK: Cluster loads SU(2) - SU(1)
+; CHECK: Cluster ld/st SU(2) - SU(1)
 ; CHECK: SU(1):   %vreg{{[0-9]+}}<def> = LDURWi
 ; CHECK: SU(2):   %vreg{{[0-9]+}}<def> = LDURWi
 define i32 @ldur_int(i32* %a) nounwind {
   %p1 = getelementptr inbounds i32, i32* %a, i32 -1
   %tmp1 = load i32, i32* %p1, align 2
   %p2 = getelementptr inbounds i32, i32* %a, i32 -2
   %tmp2 = load i32, i32* %p2, align 2
   %tmp3 = add i32 %tmp1, %tmp2
   ret i32 %tmp3
 }
 
 ; Test sext + zext clustering.
 ; CHECK: ********** MI Scheduling **********
 ; CHECK-LABEL: ldp_half_sext_zext_int:BB#0
-; CHECK: Cluster loads SU(3) - SU(4)
+; CHECK: Cluster ld/st SU(3) - SU(4)
 ; CHECK: SU(3):   %vreg{{[0-9]+}}<def> = LDRSWui
 ; CHECK: SU(4):   %vreg{{[0-9]+}}:sub_32<def,read-undef> = LDRWui
 define i64 @ldp_half_sext_zext_int(i64* %q, i32* %p) nounwind {
   %tmp0 = load i64, i64* %q, align 4
   %tmp = load i32, i32* %p, align 4
   %add.ptr = getelementptr inbounds i32, i32* %p, i64 1
   %tmp1 = load i32, i32* %add.ptr, align 4
   %sexttmp = sext i32 %tmp to i64
   %sexttmp1 = zext i32 %tmp1 to i64
   %add = add nsw i64 %sexttmp1, %sexttmp
   %add1 = add nsw i64 %add, %tmp0
   ret i64 %add1
 }
 
 ; Test zext + sext clustering.
 ; CHECK: ********** MI Scheduling **********
 ; CHECK-LABEL: ldp_half_zext_sext_int:BB#0
-; CHECK: Cluster loads SU(3) - SU(4)
+; CHECK: Cluster ld/st SU(3) - SU(4)
 ; CHECK: SU(3):   %vreg{{[0-9]+}}:sub_32<def,read-undef> = LDRWui
 ; CHECK: SU(4):   %vreg{{[0-9]+}}<def> = LDRSWui
 define i64 @ldp_half_zext_sext_int(i64* %q, i32* %p) nounwind {
   %tmp0 = load i64, i64* %q, align 4
   %tmp = load i32, i32* %p, align 4
   %add.ptr = getelementptr inbounds i32, i32* %p, i64 1
   %tmp1 = load i32, i32* %add.ptr, align 4
   %sexttmp = zext i32 %tmp to i64
   %sexttmp1 = sext i32 %tmp1 to i64
   %add = add nsw i64 %sexttmp1, %sexttmp
   %add1 = add nsw i64 %add, %tmp0
   ret i64 %add1
 }
 
 ; Verify we don't cluster volatile loads.
 ; CHECK: ********** MI Scheduling **********
 ; CHECK-LABEL: ldr_int_volatile:BB#0
-; CHECK-NOT: Cluster loads
+; CHECK-NOT: Cluster ld/st
 ; CHECK: SU(1):   %vreg{{[0-9]+}}<def> = LDRWui
 ; CHECK: SU(2):   %vreg{{[0-9]+}}<def> = LDRWui
 define i32 @ldr_int_volatile(i32* %a) nounwind {
   %p1 = getelementptr inbounds i32, i32* %a, i32 1
   %tmp1 = load volatile i32, i32* %p1, align 2
   %p2 = getelementptr inbounds i32, i32* %a, i32 2
   %tmp2 = load volatile i32, i32* %p2, align 2
   %tmp3 = add i32 %tmp1, %tmp2
   ret i32 %tmp3
 }

test/CodeGen/AArch64/arm64-stp.ll

; CHECK: ret
   %p20 = insertelement <4 x i32> %p19, i32 %v, i32 3
   %p21 = bitcast i32* %p to <4 x i32>*
   store <4 x i32> %p20, <4 x i32>* %p21, align 4
   ret void
 }
 
 ; Read of %b to compute %tmp2 shouldn't prevent formation of stp
 ; CHECK-LABEL: stp_int_rar_hazard
-; CHECK: stp w0, w1, [x2]
 ; CHECK: ldr [[REG:w[0-9]+]], [x2, #8]
-; CHECK: add w0, [[REG]], w1
+; CHECK: add w8, [[REG]], w1
+; CHECK: stp w0, w1, [x2]
 ; CHECK: ret
 define i32 @stp_int_rar_hazard(i32 %a, i32 %b, i32* nocapture %p) nounwind {
   store i32 %a, i32* %p, align 4
   %ld.ptr = getelementptr inbounds i32, i32* %p, i64 2
   %tmp = load i32, i32* %ld.ptr, align 4
   %tmp2 = add i32 %tmp, %b
   %add.ptr = getelementptr inbounds i32, i32* %p, i64 1
   store i32 %b, i32* %add.ptr, align 4

test/CodeGen/AArch64/global-merge-group-by-use.ll

 
 @m4 = internal global i32 0, align 4
 @n4 = internal global i32 0, align 4
 
 ; CHECK-LABEL: f4:
 define void @f4(i32 %a1, i32 %a2, i32 %a3) #0 {
 ; CHECK-NEXT: adrp x8, [[SET3]]@PAGE
 ; CHECK-NEXT: add x8, x8, [[SET3]]@PAGEOFF
-; CHECK-NEXT: stp w0, w1, [x8, #4]
-; CHECK-NEXT: str w2, [x8]
+; CHECK-NEXT: stp w2, w0, [x8]
+; CHECK-NEXT: str w1, [x8, #8]
 ; CHECK-NEXT: ret
   store i32 %a1, i32* @m4, align 4
   store i32 %a2, i32* @n4, align 4
   store i32 %a3, i32* @n3, align 4
   ret void
 }
 
 ; Finally, check that we don't do anything with one-element global sets.