[PATCH] MachineScheduler: Allow tracking of subregister lane masks.

Tom Stellard tom at stellard.net
Thu Apr 23 17:32:56 PDT 2015


On Fri, Apr 17, 2015 at 08:44:10PM -0400, Tom Stellard wrote:
> On Fri, Apr 17, 2015 at 02:20:51AM +0000, Matthias Braun wrote:
> > Hi qcolombet, atrick, tstellarAMD,
> > 
> > Before this patch the machine scheduler was unable to reorder sequences like the following:
> >      %vreg42:sub0 = ...
> >      %vreg42:sub1 = ...
> > This patch series enables this. It is however disabled by default. Targets that benefit from this (probably R600) can enable it by change the "shouldTrackLaneMasks" flag in the SchedulingPolicy/Strategy.
> > 
> > This patch requires http://reviews.llvm.org/D9067 and http://reviews.llvm.org/D9068 to be applied first.
> > 
> 
> Hi,
> 
> I've found a crashing test case on R600 with these three patches applied
> and shouldTrackLaneMasks sett to true.  The test case is attached, you
> can reproduce it with this command:
> 
> ./llc -march=amdgcn sched-lane-crash.ll -o -
> 

Hi Matthias,

I have just tested your updated patches and found another crashing case.
See the attached test case, which you can run using:

./llc -march=amdgcn sched-lane-crash.ll -o -

-Tom

> -Tom
> 
> > About the patch:
> > 
> > Tracking lanemasks allows the scheduler to differentiate between
> > different subregister defs and schedule them independently even when
> > they go into the same vreg.
> > For this to work we have to take care that the subregister defs count as
> > register pressure neutral except for the first one. We also have to attach the
> > reads-undef marker to the first subregister def and remove it from all
> > others.
> > 
> > REPOSITORY
> >   rL LLVM
> > 
> > http://reviews.llvm.org/D9069
> > 
> > Files:
> >   include/llvm/CodeGen/MachineInstr.h
> >   include/llvm/CodeGen/MachineScheduler.h
> >   include/llvm/CodeGen/RegisterPressure.h
> >   include/llvm/CodeGen/ScheduleDAGInstrs.h
> >   lib/CodeGen/LiveIntervalAnalysis.cpp
> >   lib/CodeGen/MachineInstr.cpp
> >   lib/CodeGen/MachineScheduler.cpp
> >   lib/CodeGen/RegisterPressure.cpp
> >   lib/CodeGen/ScheduleDAGInstrs.cpp
> > 
> > EMAIL PREFERENCES
> >   http://reviews.llvm.org/settings/panel/emailpreferences/
> 
> > Index: include/llvm/CodeGen/MachineInstr.h
> > ===================================================================
> > --- include/llvm/CodeGen/MachineInstr.h
> > +++ include/llvm/CodeGen/MachineInstr.h
> > @@ -1050,7 +1050,7 @@
> >    /// Mark all subregister defs of register @p Reg with the undef flag.
> >    /// This function is used when we determined to have a subregister def in an
> >    /// otherwise undefined super register.
> > -  void addRegisterDefReadUndef(unsigned Reg);
> > +  void setRegisterDefReadUndef(unsigned Reg, bool IsUndef = true);
> >  
> >    /// addRegisterDefined - We have determined MI defines a register. Make sure
> >    /// there is an operand defining Reg.
> > Index: include/llvm/CodeGen/MachineScheduler.h
> > ===================================================================
> > --- include/llvm/CodeGen/MachineScheduler.h
> > +++ include/llvm/CodeGen/MachineScheduler.h
> > @@ -150,14 +150,17 @@
> >  struct MachineSchedPolicy {
> >    // Allow the scheduler to disable register pressure tracking.
> >    bool ShouldTrackPressure;
> > +  // Allow the schedule to track subregister defs to different lanes
> > +  // independently.
> > +  bool ShouldTrackLaneMasks;
> >  
> >    // Allow the scheduler to force top-down or bottom-up scheduling. If neither
> >    // is true, the scheduler runs in both directions and converges.
> >    bool OnlyTopDown;
> >    bool OnlyBottomUp;
> >  
> > -  MachineSchedPolicy(): ShouldTrackPressure(false), OnlyTopDown(false),
> > -    OnlyBottomUp(false) {}
> > +  MachineSchedPolicy(): ShouldTrackPressure(false), ShouldTrackLaneMasks(false),
> > +    OnlyTopDown(false), OnlyBottomUp(false) {}
> >  };
> >  
> >  /// MachineSchedStrategy - Interface to the scheduling algorithm used by
> > @@ -179,6 +182,10 @@
> >    /// initializing this strategy. Called after initPolicy.
> >    virtual bool shouldTrackPressure() const { return true; }
> >  
> > +  /// Check if lane masks should be tracked to schedule subregister defs of the
> > +  /// same vreg independently. Called after initPolicy().
> > +  virtual bool shouldTrackLaneMasks() const { return false; }
> > +
> >    /// Initialize the strategy after building the DAG for a new region.
> >    virtual void initialize(ScheduleDAGMI *DAG) = 0;
> >  
> > @@ -458,6 +465,8 @@
> >  
> >    void updatePressureDiffs(ArrayRef<unsigned> LiveUses);
> >  
> > +  void updateFirstDef(const VRegInfo &Info, const MachineInstr *ToBeScheduled);
> > +
> >    void updateScheduledPressure(const SUnit *SU,
> >                                 const std::vector<unsigned> &NewMaxPressure);
> >  };
> > @@ -866,6 +875,10 @@
> >      return RegionPolicy.ShouldTrackPressure;
> >    }
> >  
> > +  bool shouldTrackLaneMasks() const override {
> > +    return RegionPolicy.ShouldTrackLaneMasks;
> > +  }
> > +
> >    void initialize(ScheduleDAGMI *dag) override;
> >  
> >    SUnit *pickNode(bool &IsTopNode) override;
> > Index: include/llvm/CodeGen/RegisterPressure.h
> > ===================================================================
> > --- include/llvm/CodeGen/RegisterPressure.h
> > +++ include/llvm/CodeGen/RegisterPressure.h
> > @@ -304,10 +304,11 @@
> >  
> >    /// Recede across the previous instruction.
> >    bool recede(SmallVectorImpl<unsigned> *LiveUses = nullptr,
> > +              SmallVectorImpl<unsigned> *Defs = nullptr,
> >                PressureDiff *PDiff = nullptr);
> >  
> >    /// Advance across the current instruction.
> > -  bool advance();
> > +  bool advance(SmallVectorImpl<unsigned> *Defs = nullptr);
> >  
> >    /// Finalize the region boundaries and recored live ins and live outs.
> >    void closeRegion();
> > Index: include/llvm/CodeGen/ScheduleDAGInstrs.h
> > ===================================================================
> > --- include/llvm/CodeGen/ScheduleDAGInstrs.h
> > +++ include/llvm/CodeGen/ScheduleDAGInstrs.h
> > @@ -43,6 +43,19 @@
> >      }
> >    };
> >  
> > +  struct VRegInfo {
> > +    unsigned VirtReg;
> > +    unsigned NumUnscheduledDefSUs : 31;
> > +    bool     LiveIn               :  1;
> > +
> > +    VRegInfo(unsigned VReg)
> > +      : VirtReg(VReg), NumUnscheduledDefSUs(0), LiveIn(false) {}
> > +
> > +    unsigned getSparseSetIndex() const {
> > +      return TargetRegisterInfo::virtReg2Index(VirtReg);
> > +    }
> > +  };
> > +
> >    /// Record a physical register access.
> >    /// For non-data-dependent uses, OpIdx == -1.
> >    struct PhysRegSUOper {
> > @@ -72,6 +85,8 @@
> >    /// vreg use list.
> >    typedef SparseMultiSet<VReg2SUnit, VirtReg2IndexFunctor> VReg2SUnitMultiMap;
> >  
> > +  typedef SparseSet<VRegInfo, VirtReg2IndexFunctor> VRegInfoMap;
> > +
> >    /// ScheduleDAGInstrs - A ScheduleDAG subclass for scheduling lists of
> >    /// MachineInstrs.
> >    class ScheduleDAGInstrs : public ScheduleDAG {
> > @@ -122,6 +137,12 @@
> >      /// is mapped to a set of SUnits. These include all local vreg uses, not
> >      /// just the uses for a singly defined vreg.
> >      VReg2SUnitMultiMap VRegUses;
> > +    /// After calling BuildSchedGraph, each vreg def in the scheduling region
> > +    /// is mapped to a set of SUnits.
> > +    VReg2SUnitMultiMap VRegDefs;
> > +
> > +    /// Information (mostly the number of unscheduled defs left) about a vreg.
> > +    VRegInfoMap VRegInfos;
> >  
> >      /// State internal to DAG building.
> >      /// -------------------------------
> > Index: lib/CodeGen/LiveIntervalAnalysis.cpp
> > ===================================================================
> > --- lib/CodeGen/LiveIntervalAnalysis.cpp
> > +++ lib/CodeGen/LiveIntervalAnalysis.cpp
> > @@ -469,7 +469,7 @@
> >      if (MRI->shouldTrackSubRegLiveness(LI.reg)) {
> >        if ((I == LI.begin() || std::prev(I)->end < Def) && !VNI->isPHIDef()) {
> >          MachineInstr *MI = getInstructionFromIndex(Def);
> > -        MI->addRegisterDefReadUndef(LI.reg);
> > +        MI->setRegisterDefReadUndef(LI.reg);
> >        }
> >      }
> >  
> > Index: lib/CodeGen/MachineInstr.cpp
> > ===================================================================
> > --- lib/CodeGen/MachineInstr.cpp
> > +++ lib/CodeGen/MachineInstr.cpp
> > @@ -1863,11 +1863,11 @@
> >    }
> >  }
> >  
> > -void MachineInstr::addRegisterDefReadUndef(unsigned Reg) {
> > +void MachineInstr::setRegisterDefReadUndef(unsigned Reg, bool IsUndef) {
> >    for (MachineOperand &MO : operands()) {
> >      if (!MO.isReg() || !MO.isDef() || MO.getReg() != Reg || MO.getSubReg() == 0)
> >        continue;
> > -    MO.setIsUndef();
> > +    MO.setIsUndef(IsUndef);
> >    }
> >  }
> >  
> > Index: lib/CodeGen/MachineScheduler.cpp
> > ===================================================================
> > --- lib/CodeGen/MachineScheduler.cpp
> > +++ lib/CodeGen/MachineScheduler.cpp
> > @@ -859,6 +859,7 @@
> >    SUPressureDiffs.clear();
> >  
> >    ShouldTrackPressure = SchedImpl->shouldTrackPressure();
> > +  TrackLaneMasks = SchedImpl->shouldTrackLaneMasks();
> >  }
> >  
> >  // Setup the register pressure trackers for the top scheduled top and bottom
> > @@ -921,6 +922,12 @@
> >            dbgs() << TRI->getRegPressureSetName(
> >              RegionCriticalPSets[i].getPSet()) << " ";
> >          dbgs() << "\n");
> > +
> > +  if (TrackLaneMasks) {
> > +    // Set read-undef flag for VRegs with exactly one (subregister) def.
> > +    for (const VRegInfo &Info : VRegInfos)
> > +      updateFirstDef(Info, nullptr);
> > +  }
> >  }
> >  
> >  void ScheduleDAGMILive::
> > @@ -992,6 +999,48 @@
> >    }
> >  }
> >  
> > +/// Register pressure is tracked for full vregs. This means a subregister def
> > +/// does not change the register pressure as it appears to be reading+writing
> > +/// the vreg, except for the first which just writes the vreg. This means we
> > +/// have to change the pressure diffs as soon as we only have 1 def left to
> > +/// schedule and know it will become the first.
> > +/// If @p ToBeScheduled is given this node is considered as already scheduled.
> > +void ScheduleDAGMILive::updateFirstDef(const VRegInfo &Info,
> > +                                       const MachineInstr *ToBeScheduled) {
> > +  if (Info.LiveIn || Info.NumUnscheduledDefSUs != 1)
> > +    return;
> > +
> > +  unsigned VReg = Info.VirtReg;
> > +#ifndef NDEBUG
> > +  unsigned Unscheduled = 0;
> > +  for (const VReg2SUnit &V2SU
> > +       : make_range(VRegDefs.find(VReg), VRegDefs.end())) {
> > +    if (!V2SU.SU->isScheduled && V2SU.SU->getInstr() != ToBeScheduled)
> > +      ++Unscheduled;
> > +  }
> > +  assert(Unscheduled == 1 &&
> > +         "There should be exactly one other unscheduled instruction left");
> > +#endif
> > +  // There should be exactly one other unscheduled MI left which needs its
> > +  // pressure changed.
> > +  for (const VReg2SUnit &V2SU
> > +       : make_range(VRegDefs.find(VReg), VRegDefs.end())) {
> > +    SUnit *SU = V2SU.SU;
> > +    if (SU->isScheduled)
> > +      continue;
> > +    MachineInstr &MI = *SU->getInstr();
> > +    if (&MI == ToBeScheduled)
> > +      continue;
> > +    // The remaining def will be the first in line. This means it does not read
> > +    // earlier values: Change the pressure diff and add the read-undef flag.
> > +    getPressureDiff(SU).addPressureChange(VReg, false, &MRI);
> > +    MI.setRegisterDefReadUndef(VReg, true);
> > +    DEBUG(dbgs() << "  SU(" << SU->NodeNum << ") will be first def of "
> > +          << PrintVRegOrUnit(VReg, TRI) << ": " << MI);
> > +    break;
> > +  }
> > +}
> > +
> >  /// schedule - Called back from MachineScheduler::runOnMachineFunction
> >  /// after setting up the current scheduling region. [RegionBegin, RegionEnd)
> >  /// only includes instructions that have DAG nodes, not scheduling boundaries.
> > @@ -1200,9 +1249,25 @@
> >  
> >      if (ShouldTrackPressure) {
> >        // Update top scheduled pressure.
> > -      TopRPTracker.advance();
> > +      SmallVector<unsigned, 2> Defs;
> > +      TopRPTracker.advance(&Defs);
> >        assert(TopRPTracker.getPos() == CurrentTop && "out of sync");
> >        updateScheduledPressure(SU, TopRPTracker.getPressure().MaxSetPressure);
> > +
> > +      if (TrackLaneMasks) {
> > +        // If we schedule the first of a series of subregister defs, then we
> > +        // have to mark it with the read-undef flag.
> > +        for (unsigned Reg : Defs) {
> > +          if (!TRI->isVirtualRegister(Reg))
> > +            continue;
> > +
> > +          VRegInfo &Info = *VRegInfos.find(Reg);
> > +          if (Info.LiveIn)
> > +            continue;
> > +          MI->setRegisterDefReadUndef(Reg, true);
> > +          Info.LiveIn = true;
> > +        }
> > +      }
> >      }
> >    }
> >    else {
> > @@ -1222,10 +1287,23 @@
> >      if (ShouldTrackPressure) {
> >        // Update bottom scheduled pressure.
> >        SmallVector<unsigned, 8> LiveUses;
> > -      BotRPTracker.recede(&LiveUses);
> > +      SmallVector<unsigned, 2> Defs;
> > +      BotRPTracker.recede(&LiveUses, &Defs);
> >        assert(BotRPTracker.getPos() == CurrentBottom && "out of sync");
> >        updateScheduledPressure(SU, BotRPTracker.getPressure().MaxSetPressure);
> >        updatePressureDiffs(LiveUses);
> > +
> > +      if (TrackLaneMasks) {
> > +        for (unsigned Reg : Defs) {
> > +          if (!TRI->isVirtualRegister(Reg))
> > +            continue;
> > +
> > +          VRegInfo &Info = *VRegInfos.find(Reg);
> > +          assert(Info.NumUnscheduledDefSUs > 0);
> > +          --Info.NumUnscheduledDefSUs;
> > +          updateFirstDef(Info, MI);
> > +        }
> > +      }
> >      }
> >    }
> >  }
> > Index: lib/CodeGen/RegisterPressure.cpp
> > ===================================================================
> > --- lib/CodeGen/RegisterPressure.cpp
> > +++ lib/CodeGen/RegisterPressure.cpp
> > @@ -456,6 +456,7 @@
> >  /// difference pointer is provided record the changes is pressure caused by this
> >  /// instruction independent of liveness.
> >  bool RegPressureTracker::recede(SmallVectorImpl<unsigned> *LiveUses,
> > +                                SmallVectorImpl<unsigned> *Defs,
> >                                  PressureDiff *PDiff) {
> >    // Check for the top of the analyzable region.
> >    if (CurrPos == MBB->begin()) {
> > @@ -500,6 +501,9 @@
> >    // TODO: consider earlyclobbers?
> >    for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) {
> >      unsigned Reg = RegOpers.Defs[i];
> > +    if (Defs != nullptr && !containsReg(*Defs, Reg))
> > +      Defs->push_back(Reg);
> > +
> >      bool DeadDef = false;
> >      if (RequireIntervals) {
> >        const LiveRange *LR = getLiveRange(Reg);
> > @@ -552,7 +556,7 @@
> >  }
> >  
> >  /// Advance across the current instruction.
> > -bool RegPressureTracker::advance() {
> > +bool RegPressureTracker::advance(SmallVectorImpl<unsigned> *Defs) {
> >    assert(!TrackUntiedDefs && "unsupported mode");
> >  
> >    // Check for the bottom of the analyzable region.
> > @@ -605,6 +609,8 @@
> >    // Generate liveness for defs.
> >    for (unsigned i = 0, e = RegOpers.Defs.size(); i < e; ++i) {
> >      unsigned Reg = RegOpers.Defs[i];
> > +    if (Defs != nullptr && !containsReg(*Defs, Reg))
> > +      Defs->push_back(Reg);
> >      if (LiveRegs.insert(Reg))
> >        increaseRegPressure(Reg);
> >    }
> > Index: lib/CodeGen/ScheduleDAGInstrs.cpp
> > ===================================================================
> > --- lib/CodeGen/ScheduleDAGInstrs.cpp
> > +++ lib/CodeGen/ScheduleDAGInstrs.cpp
> > @@ -388,18 +388,42 @@
> >  /// TODO: Hoist loop induction variable increments. This has to be
> >  /// reevaluated. Generally, IV scheduling should be done before coalescing.
> >  void ScheduleDAGInstrs::addVRegDefDeps(SUnit *SU, unsigned OperIdx) {
> > -  const MachineInstr *MI = SU->getInstr();
> > -  const MachineOperand &MO = MI->getOperand(OperIdx);
> > +  MachineInstr *MI = SU->getInstr();
> > +  MachineOperand &MO = MI->getOperand(OperIdx);
> >    unsigned Reg = MO.getReg();
> >    unsigned DefLaneMask = getLaneMaskForMO(MO);
> > +  // Remember the isUndef flag, as we may reset it in a bit.
> > +  bool IsKill = MO.getSubReg() == 0 || MO.isUndef();
> > +
> > +  VRegInfo *RegInfo = nullptr;
> > +  if (TrackLaneMasks) {
> > +    auto IteratorBoolPair = VRegInfos.insert(VRegInfo(Reg));
> > +    RegInfo = &*(IteratorBoolPair.first);
> > +    RegInfo->LiveIn = !IsKill;
> > +    // Clear undef flag, we'll re-add it later once we know which Def is first.
> > +    MO.setIsUndef(false);
> > +  }
> >  
> > +  // Record this local VReg Def.
> >    if (MO.isDead()) {
> >      assert(CurrentVRegUses.find(Reg) == CurrentVRegUses.end() &&
> >             "Dead defs should have no uses");
> >    } else {
> > +    if (TrackLaneMasks) {
> > +      VReg2SUnitMultiMap::iterator UI = VRegDefs.find(Reg);
> > +      for (; UI != VRegDefs.end(); ++UI) {
> > +        if (UI->SU == SU)
> > +          break;
> > +      }
> > +      if (UI == VRegDefs.end()) {
> > +        VRegDefs.insert(VReg2SUnit(Reg, 0, SU));
> > +        ++RegInfo->NumUnscheduledDefSUs;
> > +      }
> > +    }
> > +
> >      // If we have a <read-undef> flag, none of the lane values comes from an
> >      // earlier instruction.
> > -    unsigned KillLaneMask = MO.isUndef() ? ~0u : DefLaneMask;
> > +    unsigned KillLaneMask = IsKill ? ~0u : DefLaneMask;
> >      // Add data dependence to all uses we found so far.
> >      const TargetSubtargetInfo &ST = MF.getSubtarget();
> >      for (VReg2SUnitMultiMap::iterator I = CurrentVRegUses.find(Reg),
> > @@ -853,6 +877,12 @@
> >  
> >    VRegUses.clear();
> >    VRegUses.setUniverse(NumVirtRegs);
> > +  VRegDefs.clear();
> > +  VRegInfos.clear();
> > +  if (TrackLaneMasks) {
> > +    VRegDefs.setUniverse(NumVirtRegs);
> > +    VRegInfos.setUniverse(NumVirtRegs);
> > +  }
> >  
> >    // Model data dependencies between instructions being scheduled and the
> >    // ExitSU.
> > @@ -875,13 +905,6 @@
> >      SUnit *SU = MISUnitMap[MI];
> >      assert(SU && "No SUnit mapped to this MI");
> >  
> > -    if (RPTracker) {
> > -      PressureDiff *PDiff = PDiffs ? &(*PDiffs)[SU->NodeNum] : nullptr;
> > -      RPTracker->recede(/*LiveUses=*/nullptr, PDiff);
> > -      assert(RPTracker->getPos() == std::prev(MII) &&
> > -             "RPTracker can't find MI");
> > -    }
> > -
> >      assert(
> >          (CanHandleTerminators || (!MI->isTerminator() && !MI->isPosition())) &&
> >          "Cannot schedule terminators or labels!");
> > @@ -1124,6 +1147,13 @@
> >            BarrierChain->addPred(SDep(SU, SDep::Barrier));
> >        }
> >      }
> > +
> > +    if (RPTracker) {
> > +      PressureDiff *PDiff = PDiffs ? &(*PDiffs)[SU->NodeNum] : nullptr;
> > +      RPTracker->recede(/*LiveUses=*/nullptr, /*Defs=*/nullptr, PDiff);
> > +      assert(RPTracker->getPos() == std::prev(MII) &&
> > +             "RPTracker can't find MI");
> > +    }
> >    }
> >    if (DbgMI)
> >      FirstDbgValue = DbgMI;
> 
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> 

> ; ModuleID = 'bugpoint-reduced-simplified.bc'
> 
> define void @main([6 x <16 x i8>] addrspace(2)* byval, [17 x <16 x i8>] addrspace(2)* byval, [17 x <4 x i32>] addrspace(2)* byval, [34 x <8 x i32>] addrspace(2)* byval, float inreg, i32 inreg, <2 x i32>, <2 x i32>, <2 x i32>, <3 x i32>, <2 x i32>, <2 x i32>, <2 x i32>, float, float, float, float, float, float, i32, float, float) #0 {
> main_body:
>   %22 = call <4 x float> @llvm.AMDGPU.cube(<4 x float> zeroinitializer)
>   %23 = extractelement <4 x float> %22, i32 2
>   %24 = call float @fabs(float %23)
>   %25 = fdiv float 1.000000e+00, %24
>   %26 = fmul float undef, %25
>   %27 = fadd float %26, 1.500000e+00
>   %28 = bitcast float %27 to i32
>   %29 = insertelement <4 x i32> undef, i32 %28, i32 1
>   %30 = insertelement <4 x i32> %29, i32 undef, i32 2
>   %31 = call <4 x float> @llvm.SI.sample.v4i32(<4 x i32> %30, <32 x i8> undef, <16 x i8> undef, i32 4)
>   %32 = extractelement <4 x float> %31, i32 0
>   %33 = fcmp olt float undef, %32
>   %34 = select i1 %33, float 1.000000e+00, float 0.000000e+00
>   %35 = fmul float undef, %34
>   %36 = fmul float %35, 0.000000e+00
>   %37 = fmul float %36, undef
>   %38 = fadd float %37, undef
>   %39 = fmul float undef, undef
>   %40 = fmul float %39, 0.000000e+00
>   %41 = fmul float %40, undef
>   %42 = fadd float %41, %38
>   %43 = fadd float undef, %42
>   call void @llvm.SI.export(i32 15, i32 1, i32 1, i32 0, i32 0, float %43, float undef, float undef, float 0.000000e+00)
>   ret void
> }
> 
> ; Function Attrs: nounwind readnone
> declare float @llvm.SI.load.const(<16 x i8>, i32) #1
> 
> ; Function Attrs: nounwind readnone
> declare float @llvm.SI.fs.interp(i32, i32, i32, <2 x i32>) #1
> 
> ; Function Attrs: nounwind readnone
> declare float @llvm.maxnum.f32(float, float) #1
> 
> ; Function Attrs: nounwind readnone
> declare float @llvm.AMDGPU.rsq.clamped.f32(float) #1
> 
> ; Function Attrs: nounwind readnone
> declare <4 x float> @llvm.SI.sample.v2i32(<2 x i32>, <32 x i8>, <16 x i8>, i32) #1
> 
> ; Function Attrs: nounwind readnone
> declare float @llvm.sqrt.f32(float) #1
> 
> ; Function Attrs: readnone
> declare <4 x float> @llvm.AMDGPU.cube(<4 x float>) #2
> 
> ; Function Attrs: readnone
> declare float @fabs(float) #2
> 
> ; Function Attrs: nounwind readnone
> declare <4 x float> @llvm.SI.sample.v4i32(<4 x i32>, <32 x i8>, <16 x i8>, i32) #1
> 
> ; Function Attrs: readnone
> declare float @llvm.AMDIL.clamp.(float, float, float) #2
> 
> ; Function Attrs: nounwind readnone
> declare float @llvm.pow.f32(float, float) #1
> 
> declare void @llvm.SI.export(i32, i32, i32, i32, i32, float, float, float, float)
> 
> attributes #0 = { "ShaderType"="0" "enable-no-nans-fp-math"="true" }
> attributes #1 = { nounwind readnone }
> attributes #2 = { readnone }

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-------------- next part --------------
; ModuleID = 'bugpoint-reduced-simplified.bc'
target triple = "x86_64-unknown-linux-gnu"

define void @main() #0 {
main_body:
  %0 = call float @llvm.SI.load.const(<16 x i8> undef, i32 104)
  %1 = fmul float undef, undef
  %2 = fadd float %1, undef
  %3 = fadd float undef, undef
  %4 = fadd float %2, undef
  %5 = fsub float %3, 0.000000e+00
  %6 = fsub float %4, %0
  %7 = fadd float %5, 7.812500e-03
  %8 = fadd float %6, -7.812500e-03
  %9 = insertelement <4 x float> undef, float %7, i32 1
  %10 = insertelement <4 x float> %9, float %8, i32 2
  %11 = insertelement <4 x float> %10, float 0.000000e+00, i32 3
  %12 = call <4 x float> @llvm.AMDGPU.cube(<4 x float> %11)
  %13 = extractelement <4 x float> %12, i32 3
  %14 = bitcast float %13 to i32
  %15 = insertelement <4 x i32> undef, i32 %14, i32 2
  %16 = call <4 x float> @llvm.SI.sample.v4i32(<4 x i32> %15, <32 x i8> undef, <16 x i8> zeroinitializer, i32 4)
  %17 = extractelement <4 x float> %16, i32 0
  %18 = fcmp olt float %17, 0.000000e+00
  %19 = select i1 %18, float 0.000000e+00, float 2.500000e-01
  %20 = fadd float undef, %19
  %21 = fadd float %20, 0.000000e+00
  %22 = fmul float undef, %21
  %23 = fmul float undef, %22
  %24 = fmul float undef, %23
  %25 = fmul float %24, undef
  %26 = fadd float %25, 0.000000e+00
  %27 = fsub float -0.000000e+00, %26
  %28 = call float @llvm.AMDIL.exp.(float %27)
  call void @llvm.SI.export(i32 15, i32 1, i32 1, i32 0, i32 0, float undef, float %28, float undef, float undef)
  ret void
}

; Function Attrs: nounwind readnone
declare float @llvm.SI.load.const(<16 x i8>, i32) #1

; Function Attrs: readnone
declare <4 x float> @llvm.AMDGPU.cube(<4 x float>) #2

; Function Attrs: nounwind readnone
declare <4 x float> @llvm.SI.sample.v4i32(<4 x i32>, <32 x i8>, <16 x i8>, i32) #1

; Function Attrs: readnone
declare float @llvm.AMDIL.exp.(float) #2

declare void @llvm.SI.export(i32, i32, i32, i32, i32, float, float, float, float)

attributes #0 = { "ShaderType"="0" "enable-no-nans-fp-math"="true" }
attributes #1 = { nounwind readnone }
attributes #2 = { readnone }


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