[llvm] [AMDGPU] Fix GCNUpwardRPTracker. (WIP) (PR #71186)

Valery Pykhtin via llvm-commits llvm-commits at lists.llvm.org
Fri Nov 3 07:27:27 PDT 2023


https://github.com/vpykhtin created https://github.com/llvm/llvm-project/pull/71186

This is an early-preview, this patch is going to fix:

1. Maximum register pressure calculation at the instruction level. 
Previously max RP included both def and use of registers of an instruction. Now maximum RP includes _uses_ and _early-clobber defs_.

2. Uses were incorrectly tracked and this resulted in a mismatch of live-in set reported by LiveIntervals and tracked live reg set when the beginning of the block is reached.

Interface has changed, moveMaxPressure becomes deprecated and  getMaxPressure, resetMaxPressure functions are added. reset function seem now more consistent.

GCNUpwardRPTracker interface may seem a bit strange but I would like to clarify what I had in mind when created it.

The idea was to have a tracker that can work on non-implemented tentative schedules, that is:
1. Instruction order is maintained externally, like in array.
2. LiveIntervals and dead/kill flags aren't updated on a tentative schedule.

For this reason it has no functions to advance to next instruction, it should not use dead/kill flags. It only uses LiveIntervals information to track usage of a register with subregs and to calculate starting live register set. The idea is that _lane bitmask of a reg's use_ should be the same for any schedule.

>From e2254cb744adb65685edeb2373f900368c11c11a Mon Sep 17 00:00:00 2001
From: Valery Pykhtin <valery.pykhtin at gmail.com>
Date: Thu, 2 Nov 2023 20:39:11 +0100
Subject: [PATCH] [AMDGPU] Fix GCNUpwardRPTracker.

---
 .../Target/AMDGPU/GCNIterativeScheduler.cpp   |   4 +-
 llvm/lib/Target/AMDGPU/GCNRegPressure.cpp     | 135 ++++++++---------
 llvm/lib/Target/AMDGPU/GCNRegPressure.h       |  47 ++++--
 .../CodeGen/AMDGPU/regpressure_printer.mir    | 137 +++++++++++-------
 4 files changed, 190 insertions(+), 133 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/GCNIterativeScheduler.cpp b/llvm/lib/Target/AMDGPU/GCNIterativeScheduler.cpp
index d89c9b1febded0f..cdc9de7f65e3e50 100644
--- a/llvm/lib/Target/AMDGPU/GCNIterativeScheduler.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNIterativeScheduler.cpp
@@ -251,7 +251,7 @@ GCNIterativeScheduler::getRegionPressure(MachineBasicBlock::iterator Begin,
   assert(UPTracker.isValid() ||
          (dbgs() << "Tracked region ",
           printRegion(dbgs(), Begin, End, LIS), false));
-  return UPTracker.moveMaxPressure();
+  return UPTracker.getMaxPressureAndReset();
 }
 
 // returns max pressure for a tentative schedule
@@ -272,7 +272,7 @@ GCNIterativeScheduler::getSchedulePressure(const Region &R,
   for (auto I = Schedule.end(), B = Schedule.begin(); I != B;) {
     RPTracker.recede(*getMachineInstr(*--I));
   }
-  return RPTracker.moveMaxPressure();
+  return RPTracker.getMaxPressureAndReset();
 }
 
 void GCNIterativeScheduler::enterRegion(MachineBasicBlock *BB, // overridden
diff --git a/llvm/lib/Target/AMDGPU/GCNRegPressure.cpp b/llvm/lib/Target/AMDGPU/GCNRegPressure.cpp
index a04c470b7b9762f..f191f3f08c56c6d 100644
--- a/llvm/lib/Target/AMDGPU/GCNRegPressure.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNRegPressure.cpp
@@ -166,66 +166,62 @@ static LaneBitmask getDefRegMask(const MachineOperand &MO,
     MRI.getTargetRegisterInfo()->getSubRegIndexLaneMask(MO.getSubReg());
 }
 
-static LaneBitmask getUsedRegMask(const MachineOperand &MO,
-                                  const MachineRegisterInfo &MRI,
-                                  const LiveIntervals &LIS) {
-  assert(MO.isUse() && MO.isReg() && MO.getReg().isVirtual());
-
-  if (auto SubReg = MO.getSubReg())
-    return MRI.getTargetRegisterInfo()->getSubRegIndexLaneMask(SubReg);
-
-  auto MaxMask = MRI.getMaxLaneMaskForVReg(MO.getReg());
-  if (SIRegisterInfo::getNumCoveredRegs(MaxMask) > 1) // cannot have subregs
-    return MaxMask;
-
-  // For a tentative schedule LIS isn't updated yet but livemask should remain
-  // the same on any schedule. Subreg defs can be reordered but they all must
-  // dominate uses anyway.
-  auto SI = LIS.getInstructionIndex(*MO.getParent()).getBaseIndex();
-  return getLiveLaneMask(MO.getReg(), SI, LIS, MRI);
-}
-
-static SmallVector<RegisterMaskPair, 8>
-collectVirtualRegUses(const MachineInstr &MI, const LiveIntervals &LIS,
+static void
+collectVirtualRegUses(SmallVectorImpl<RegisterMaskPair> &RegMaskPairs,
+                      const MachineInstr &MI, const LiveIntervals &LIS,
                       const MachineRegisterInfo &MRI) {
-  SmallVector<RegisterMaskPair, 8> Res;
+  SlotIndex InstrSI;
   for (const auto &MO : MI.operands()) {
     if (!MO.isReg() || !MO.getReg().isVirtual())
       continue;
     if (!MO.isUse() || !MO.readsReg())
       continue;
 
-    auto const UsedMask = getUsedRegMask(MO, MRI, LIS);
+    Register Reg = MO.getReg();
+    auto I = llvm::find_if(RegMaskPairs, [Reg](const RegisterMaskPair &RM) {
+      return RM.RegUnit == Reg;
+    });
+    if (I != RegMaskPairs.end())
+      continue;
+      
+    LaneBitmask UseMask;
+    auto &LI = LIS.getInterval(Reg);
+    if (!LI.hasSubRanges())
+      UseMask = MRI.getMaxLaneMaskForVReg(Reg);
+    else {
+      // For a tentative schedule LIS isn't updated yet but livemask should
+      // remain the same on any schedule. Subreg defs can be reordered but they
+      // all must dominate uses anyway.
+      if (!InstrSI)
+        InstrSI = LIS.getInstructionIndex(*MO.getParent()).getBaseIndex();
+      UseMask = getLiveLaneMask(LI, InstrSI, MRI);
+    }
 
-    auto Reg = MO.getReg();
-    auto I = llvm::find_if(
-        Res, [Reg](const RegisterMaskPair &RM) { return RM.RegUnit == Reg; });
-    if (I != Res.end())
-      I->LaneMask |= UsedMask;
-    else
-      Res.push_back(RegisterMaskPair(Reg, UsedMask));
+    RegMaskPairs.emplace_back(Reg, UseMask);
   }
-  return Res;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // GCNRPTracker
 
-LaneBitmask llvm::getLiveLaneMask(unsigned Reg,
-                                  SlotIndex SI,
+LaneBitmask llvm::getLiveLaneMask(unsigned Reg, SlotIndex SI,
                                   const LiveIntervals &LIS,
                                   const MachineRegisterInfo &MRI) {
+  return getLiveLaneMask(LIS.getInterval(Reg), SI, MRI);
+}
+
+LaneBitmask llvm::getLiveLaneMask(const LiveInterval &LI, SlotIndex SI,
+                                  const MachineRegisterInfo &MRI) {
   LaneBitmask LiveMask;
-  const auto &LI = LIS.getInterval(Reg);
   if (LI.hasSubRanges()) {
     for (const auto &S : LI.subranges())
       if (S.liveAt(SI)) {
         LiveMask |= S.LaneMask;
-        assert(LiveMask < MRI.getMaxLaneMaskForVReg(Reg) ||
-               LiveMask == MRI.getMaxLaneMaskForVReg(Reg));
+        assert(LiveMask < MRI.getMaxLaneMaskForVReg(LI.reg()) ||
+               LiveMask == MRI.getMaxLaneMaskForVReg(LI.reg()));
       }
   } else if (LI.liveAt(SI)) {
-    LiveMask = MRI.getMaxLaneMaskForVReg(Reg);
+    LiveMask = MRI.getMaxLaneMaskForVReg(LI.reg());
   }
   return LiveMask;
 }
@@ -261,15 +257,11 @@ void GCNRPTracker::reset(const MachineInstr &MI,
   MaxPressure = CurPressure = getRegPressure(*MRI, LiveRegs);
 }
 
-void GCNUpwardRPTracker::reset(const MachineInstr &MI,
-                               const LiveRegSet *LiveRegsCopy) {
-  GCNRPTracker::reset(MI, LiveRegsCopy, true);
-}
-
 void GCNUpwardRPTracker::reset(const MachineRegisterInfo &MRI_,
                                const LiveRegSet &LiveRegs_) {
   MRI = &MRI_;
   LiveRegs = LiveRegs_;
+  LastTrackedMI = nullptr; // TODO: LastTrackedMI isnt' used, remove?
   MaxPressure = CurPressure = getRegPressure(MRI_, LiveRegs_);
 }
 
@@ -281,38 +273,49 @@ void GCNUpwardRPTracker::recede(const MachineInstr &MI) {
   if (MI.isDebugInstr())
     return;
 
-  auto const RegUses = collectVirtualRegUses(MI, LIS, *MRI);
-
-  // calc pressure at the MI (defs + uses)
-  auto AtMIPressure = CurPressure;
-  for (const auto &U : RegUses) {
-    auto LiveMask = LiveRegs[U.RegUnit];
-    AtMIPressure.inc(U.RegUnit, LiveMask, LiveMask | U.LaneMask, *MRI);
-  }
-  // update max pressure
-  MaxPressure = max(AtMIPressure, MaxPressure);
-
-  for (const auto &MO : MI.all_defs()) {
-    if (!MO.getReg().isVirtual() || MO.isDead())
-      continue;
-
-    auto Reg = MO.getReg();
+  auto DecrementDef = [this](const MachineOperand &MO) {
+    Register Reg = MO.getReg();
     auto I = LiveRegs.find(Reg);
     if (I == LiveRegs.end())
-      continue;
-    auto &LiveMask = I->second;
-    auto PrevMask = LiveMask;
+      return;
+
+    LaneBitmask &LiveMask = I->second;
+    LaneBitmask PrevMask = LiveMask;
     LiveMask &= ~getDefRegMask(MO, *MRI);
     CurPressure.inc(Reg, PrevMask, LiveMask, *MRI);
     if (LiveMask.none())
       LiveRegs.erase(I);
+  };
+
+  // Decrement non-early-clobber defs.
+  SmallVector<const MachineOperand *, 2> EarlyClobberDefs;
+  for (const MachineOperand &MO : MI.all_defs()) {
+    if (!MO.getReg().isVirtual())
+      continue;
+    if (!MO.isEarlyClobber())
+      DecrementDef(MO);
+    else
+      EarlyClobberDefs.push_back(&MO);
   }
-  for (const auto &U : RegUses) {
-    auto &LiveMask = LiveRegs[U.RegUnit];
-    auto PrevMask = LiveMask;
+
+  // Increment uses.
+  SmallVector<RegisterMaskPair, 8> RegUses;
+  collectVirtualRegUses(RegUses, MI, LIS, *MRI);
+  for (const RegisterMaskPair &U : RegUses) {
+    LaneBitmask &LiveMask = LiveRegs[U.RegUnit];
+    LaneBitmask PrevMask = LiveMask;
     LiveMask |= U.LaneMask;
     CurPressure.inc(U.RegUnit, PrevMask, LiveMask, *MRI);
   }
+
+  // Point of maximum pressure: non-early-clobber defs are decremented and uses
+  // are incremented.
+  MaxPressure = max(CurPressure, MaxPressure);
+
+  // Now decrement early clobber defs.
+  for (const MachineOperand *MO : EarlyClobberDefs)
+    DecrementDef(*MO);
+
   assert(CurPressure == getRegPressure(*MRI, LiveRegs));
 }
 
@@ -562,15 +565,15 @@ bool GCNRegPressurePrinter::runOnMachineFunction(MachineFunction &MF) {
     } else {
       GCNUpwardRPTracker RPT(LIS);
       RPT.reset(MRI, MBBEndSlot);
-      RPT.moveMaxPressure(); // Clear max pressure.
 
       LiveOut = RPT.getLiveRegs();
       RPAtMBBEnd = RPT.getPressure();
 
       for (auto &MI : reverse(MBB)) {
+        RPT.resetMaxPressure();
         RPT.recede(MI);
         if (!MI.isDebugInstr())
-          RP.emplace_back(RPT.getPressure(), RPT.moveMaxPressure());
+          RP.emplace_back(RPT.getPressure(), RPT.getMaxPressure());
       }
 
       LiveIn = RPT.getLiveRegs();
diff --git a/llvm/lib/Target/AMDGPU/GCNRegPressure.h b/llvm/lib/Target/AMDGPU/GCNRegPressure.h
index c750fe74749e2b3..732ed33337d24dc 100644
--- a/llvm/lib/Target/AMDGPU/GCNRegPressure.h
+++ b/llvm/lib/Target/AMDGPU/GCNRegPressure.h
@@ -128,7 +128,7 @@ class GCNRPTracker {
 
   void clearMaxPressure() { MaxPressure.clear(); }
 
-  GCNRegPressure getPressure() const { return CurPressure; }
+  const GCNRegPressure &getPressure() const { return CurPressure; }
 
   // returns MaxPressure, resetting it
   decltype(MaxPressure) moveMaxPressure() {
@@ -149,24 +149,46 @@ class GCNUpwardRPTracker : public GCNRPTracker {
 public:
   GCNUpwardRPTracker(const LiveIntervals &LIS_) : GCNRPTracker(LIS_) {}
 
-  // reset tracker to the point just below MI
-  // filling live regs upon this point using LIS
-  void reset(const MachineInstr &MI, const LiveRegSet *LiveRegs = nullptr);
-
   // reset tracker and set live register set to the specified value.
   void reset(const MachineRegisterInfo &MRI_, const LiveRegSet &LiveRegs_);
 
   // reset tracker at the specified slot index.
-  void reset(const MachineRegisterInfo &MRI_, SlotIndex SI) {
-    reset(MRI_, llvm::getLiveRegs(SI, LIS, MRI_));
+  void reset(const MachineRegisterInfo &MRI, SlotIndex SI) {
+    reset(MRI, llvm::getLiveRegs(SI, LIS, MRI));
+  }
+
+  // reset tracker to the end of the MBB.
+  void reset(const MachineBasicBlock &MBB) {
+    reset(MBB.getParent()->getRegInfo(),
+          LIS.getSlotIndexes()->getMBBEndIdx(&MBB));
+  }
+
+  // reset tracker to the point just after MI (in program order).
+  void reset(const MachineInstr &MI) {
+    reset(MI.getMF()->getRegInfo(), LIS.getInstructionIndex(MI).getDeadSlot());
   }
 
-  // move to the state just above the MI
+  // move to the state just before the MI (in program order).
   void recede(const MachineInstr &MI);
 
   // checks whether the tracker's state after receding MI corresponds
-  // to reported by LIS
+  // to reported by LIS.
   bool isValid() const;
+
+  // deprecated.
+  decltype(MaxPressure) moveMaxPressure() = delete;
+
+  const GCNRegPressure &getMaxPressure() const { return MaxPressure; }
+
+  void resetMaxPressure() {
+    MaxPressure = CurPressure;
+  }
+
+  GCNRegPressure getMaxPressureAndReset() { 
+    GCNRegPressure RP = MaxPressure;
+    resetMaxPressure();
+    return RP;
+  }
 };
 
 class GCNDownwardRPTracker : public GCNRPTracker {
@@ -209,6 +231,13 @@ LaneBitmask getLiveLaneMask(unsigned Reg,
                             const LiveIntervals &LIS,
                             const MachineRegisterInfo &MRI);
 
+LaneBitmask getLiveLaneMask(const LiveInterval &LI, SlotIndex SI,
+                            const MachineRegisterInfo &MRI);
+
+GCNRPTracker::LiveRegSet getLiveRegs(SlotIndex SI,
+                                     const LiveIntervals &LIS,
+                                     const MachineRegisterInfo &MRI);
+
 /// creates a map MachineInstr -> LiveRegSet
 /// R - range of iterators on instructions
 /// After - upon entry or exit of every instruction
diff --git a/llvm/test/CodeGen/AMDGPU/regpressure_printer.mir b/llvm/test/CodeGen/AMDGPU/regpressure_printer.mir
index d53050167e98bef..bb889e48aa16895 100644
--- a/llvm/test/CodeGen/AMDGPU/regpressure_printer.mir
+++ b/llvm/test/CodeGen/AMDGPU/regpressure_printer.mir
@@ -136,54 +136,28 @@ body:             |
 name:  upward_problem_lis_subregs_mismatch
 tracksRegLiveness: true
 body:             |
-  ; RPU-LABEL: name: upward_problem_lis_subregs_mismatch
-  ; RPU: bb.0:
-  ; RPU-NEXT:   Live-in:
-  ; RPU-NEXT:   SGPR  VGPR
-  ; RPU-NEXT:   0     0
-  ; RPU-NEXT:   0     1      undef %0.sub0:vreg_64 = V_MOV_B32_e32 42, implicit $exec
-  ; RPU-NEXT:   0     1
-  ; RPU-NEXT:   0     2      undef %1.sub1:vreg_64 = V_MOV_B32_e32 33, implicit $exec
-  ; RPU-NEXT:   0     2
-  ; RPU-NEXT:   Live-out: %0:0000000000000003 %1:000000000000000C
-  ; RPU-NEXT: bb.1:
-  ; RPU-NEXT:   Live-in:  %0:0000000000000003 %1:000000000000000C
-  ; RPU-NEXT:   SGPR  VGPR
-  ; RPU-NEXT:   0     2
-  ; RPU-NEXT:   Live-out: %0:0000000000000003 %1:000000000000000C
-  ; RPU-NEXT: bb.2:
-  ; RPU-NEXT:   Live-in:  %0:000000000000000F %1:000000000000000F
-  ; RPU-NEXT:   mis LIS:  %0:0000000000000003 %1:000000000000000C
-  ; RPU-NEXT:     %0 masks doesn't match: LIS reported 0000000000000003, tracked 000000000000000F
-  ; RPU-NEXT:     %1 masks doesn't match: LIS reported 000000000000000C, tracked 000000000000000F
-  ; RPU-NEXT:   SGPR  VGPR
-  ; RPU-NEXT:   0     4
-  ; RPU-NEXT:   0     4      S_NOP 0, implicit %0:vreg_64, implicit %1:vreg_64
-  ; RPU-NEXT:   0     0
-  ; RPU-NEXT:   Live-out:
-  ;
-  ; RPD-LABEL: name: upward_problem_lis_subregs_mismatch
-  ; RPD: bb.0:
-  ; RPD-NEXT:   Live-in:
-  ; RPD-NEXT:   SGPR  VGPR
-  ; RPD-NEXT:   0     0
-  ; RPD-NEXT:   0     1      undef %0.sub0:vreg_64 = V_MOV_B32_e32 42, implicit $exec
-  ; RPD-NEXT:   0     1
-  ; RPD-NEXT:   0     2      undef %1.sub1:vreg_64 = V_MOV_B32_e32 33, implicit $exec
-  ; RPD-NEXT:   0     2
-  ; RPD-NEXT:   Live-out: %0:0000000000000003 %1:000000000000000C
-  ; RPD-NEXT: bb.1:
-  ; RPD-NEXT:   Live-in:  %0:0000000000000003 %1:000000000000000C
-  ; RPD-NEXT:   SGPR  VGPR
-  ; RPD-NEXT:   0     2
-  ; RPD-NEXT:   Live-out: %0:0000000000000003 %1:000000000000000C
-  ; RPD-NEXT: bb.2:
-  ; RPD-NEXT:   Live-in:  %0:0000000000000003 %1:000000000000000C
-  ; RPD-NEXT:   SGPR  VGPR
-  ; RPD-NEXT:   0     2
-  ; RPD-NEXT:   0     2      S_NOP 0, implicit %0:vreg_64, implicit %1:vreg_64
-  ; RPD-NEXT:   0     0
-  ; RPD-NEXT:   Live-out:
+  ; RP-LABEL: name: upward_problem_lis_subregs_mismatch
+  ; RP: bb.0:
+  ; RP-NEXT:   Live-in:
+  ; RP-NEXT:   SGPR  VGPR
+  ; RP-NEXT:   0     0
+  ; RP-NEXT:   0     1      undef %0.sub0:vreg_64 = V_MOV_B32_e32 42, implicit $exec
+  ; RP-NEXT:   0     1
+  ; RP-NEXT:   0     2      undef %1.sub1:vreg_64 = V_MOV_B32_e32 33, implicit $exec
+  ; RP-NEXT:   0     2
+  ; RP-NEXT:   Live-out: %0:0000000000000003 %1:000000000000000C
+  ; RP-NEXT: bb.1:
+  ; RP-NEXT:   Live-in:  %0:0000000000000003 %1:000000000000000C
+  ; RP-NEXT:   SGPR  VGPR
+  ; RP-NEXT:   0     2
+  ; RP-NEXT:   Live-out: %0:0000000000000003 %1:000000000000000C
+  ; RP-NEXT: bb.2:
+  ; RP-NEXT:   Live-in:  %0:0000000000000003 %1:000000000000000C
+  ; RP-NEXT:   SGPR  VGPR
+  ; RP-NEXT:   0     2
+  ; RP-NEXT:   0     2      S_NOP 0, implicit %0:vreg_64, implicit %1:vreg_64
+  ; RP-NEXT:   0     0
+  ; RP-NEXT:   Live-out:
   bb.0:
     undef %0.sub0:vreg_64 = V_MOV_B32_e32 42, implicit $exec
     undef %1.sub1:vreg_64 = V_MOV_B32_e32 33, implicit $exec
@@ -217,13 +191,13 @@ body:             |
   ; RPU-NEXT:   0     7
   ; RPU-NEXT:   0     8      %4.sub0:vreg_64 = V_MOV_B32_e32 111, implicit $exec
   ; RPU-NEXT:   0     8
-  ; RPU-NEXT:   0     10     %5:vreg_64 = COPY %2:vreg_64
+  ; RPU-NEXT:   0     9      %5:vreg_64 = COPY %2:vreg_64
   ; RPU-NEXT:   0     9
   ; RPU-NEXT:   0     9      undef %6.sub0:vreg_64 = V_ADD_F32_e32 %1.sub0:vreg_64, %5.sub0:vreg_64, implicit $mode, implicit $exec
   ; RPU-NEXT:   0     8
   ; RPU-NEXT:   0     8      dead %6.sub1:vreg_64 = V_ADD_F32_e32 %1.sub1:vreg_64, %5.sub0:vreg_64, implicit $mode, implicit $exec
   ; RPU-NEXT:   0     7
-  ; RPU-NEXT:   0     8      %7:vgpr_32 = GLOBAL_LOAD_DWORD %5:vreg_64, 0, 0, implicit $exec
+  ; RPU-NEXT:   0     7      %7:vgpr_32 = GLOBAL_LOAD_DWORD %5:vreg_64, 0, 0, implicit $exec
   ; RPU-NEXT:   0     6
   ; RPU-NEXT:   0     7      %8:vreg_64 = IMPLICIT_DEF
   ; RPU-NEXT:   0     7
@@ -247,16 +221,16 @@ body:             |
   ; RPU-NEXT:   0     20
   ; RPU-NEXT:   0     21     %18:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
   ; RPU-NEXT:   0     21
-  ; RPU-NEXT:   0     22     undef %19.sub0:vreg_64 = V_ADD_F32_e32 %7:vgpr_32, %2.sub0:vreg_64, implicit $mode, implicit $exec
+  ; RPU-NEXT:   0     21     undef %19.sub0:vreg_64 = V_ADD_F32_e32 %7:vgpr_32, %2.sub0:vreg_64, implicit $mode, implicit $exec
   ; RPU-NEXT:   0     20
-  ; RPU-NEXT:   0     21     %19.sub1:vreg_64 = V_ADD_F32_e32 %3:vgpr_32, %3:vgpr_32, implicit $mode, implicit $exec
+  ; RPU-NEXT:   0     20     %19.sub1:vreg_64 = V_ADD_F32_e32 %3:vgpr_32, %3:vgpr_32, implicit $mode, implicit $exec
   ; RPU-NEXT:                DBG_VALUE
   ; RPU-NEXT:   0     20
   ; RPU-NEXT:   0     20     GLOBAL_STORE_DWORDX2 %19:vreg_64, %4:vreg_64, 32, 0, implicit $exec
   ; RPU-NEXT:   0     16
-  ; RPU-NEXT:   0     17     %11.sub0:vreg_64 = GLOBAL_LOAD_DWORD %9:vreg_64, 0, 0, implicit $exec
+  ; RPU-NEXT:   0     16     %11.sub0:vreg_64 = GLOBAL_LOAD_DWORD %9:vreg_64, 0, 0, implicit $exec
   ; RPU-NEXT:   0     15
-  ; RPU-NEXT:   0     16     %8.sub0:vreg_64 = GLOBAL_LOAD_DWORD %10:vreg_64, 0, 0, implicit $exec
+  ; RPU-NEXT:   0     15     %8.sub0:vreg_64 = GLOBAL_LOAD_DWORD %10:vreg_64, 0, 0, implicit $exec
   ; RPU-NEXT:   0     14
   ; RPU-NEXT:   0     14     dead %20:vgpr_32 = GLOBAL_LOAD_DWORD %11:vreg_64, 0, 0, implicit $exec
   ; RPU-NEXT:                DBG_VALUE
@@ -266,7 +240,7 @@ body:             |
   ; RPU-NEXT:   0     10
   ; RPU-NEXT:   0     10     dead %22:vgpr_32 = GLOBAL_LOAD_DWORD %15:vreg_64, 0, 0, implicit $exec
   ; RPU-NEXT:   0     10
-  ; RPU-NEXT:   0     11     %23:vreg_64 = V_LSHLREV_B64_e64 2, %8:vreg_64, implicit $exec
+  ; RPU-NEXT:   0     10     %23:vreg_64 = V_LSHLREV_B64_e64 2, %8:vreg_64, implicit $exec
   ; RPU-NEXT:   0     9
   ; RPU-NEXT:   0     9      S_NOP 0, implicit %13:vgpr_32, implicit %23.sub0:vreg_64, implicit %12:vgpr_32, implicit %17:vgpr_32
   ; RPU-NEXT:   0     5
@@ -459,4 +433,55 @@ body:             |
     S_NOP 0, implicit %16
     S_ENDPGM 0
 ...
-
+---
+name:  test_early_clobber_trivial
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    ; RP-LABEL: name: test_early_clobber_trivial
+    ; RP: Live-in:
+    ; RP-NEXT: SGPR  VGPR
+    ; RP-NEXT: 0     0
+    ; RP-NEXT: 0     1      %0:vgpr_32 = V_MOV_B32_e32 42, implicit $exec
+    ; RP-NEXT: 0     1
+    ; RP-NEXT: 0     2      early-clobber %1:vgpr_32 = V_MOV_B32_e32 %0:vgpr_32, implicit $exec
+    ; RP-NEXT: 0     1
+    ; RP-NEXT: 0     1      S_NOP 0, implicit %1:vgpr_32
+    ; RP-NEXT: 0     0
+    ; RP-NEXT: Live-out:
+    %0:vgpr_32 = V_MOV_B32_e32 42, implicit $exec
+    early-clobber %1:vgpr_32 = V_MOV_B32_e32 %0, implicit $exec
+    S_NOP 0, implicit %1
+...
+---
+name:  test_not_early_clobber_trivial
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    ; RPU-LABEL: name: test_not_early_clobber_trivial
+    ; RPU: Live-in:
+    ; RPU-NEXT: SGPR  VGPR
+    ; RPU-NEXT: 0     0
+    ; RPU-NEXT: 0     1      %0:vgpr_32 = V_MOV_B32_e32 42, implicit $exec
+    ; RPU-NEXT: 0     1
+    ; RPU-NEXT: 0     1      %1:vgpr_32 = V_MOV_B32_e32 %0:vgpr_32, implicit $exec
+    ; RPU-NEXT: 0     1
+    ; RPU-NEXT: 0     1      S_NOP 0, implicit %1:vgpr_32
+    ; RPU-NEXT: 0     0
+    ; RPU-NEXT: Live-out:
+    ;
+    ; RPD-LABEL: name: test_not_early_clobber_trivial
+    ; RPD: Live-in:
+    ; RPD-NEXT: SGPR  VGPR
+    ; RPD-NEXT: 0     0
+    ; RPD-NEXT: 0     1      %0:vgpr_32 = V_MOV_B32_e32 42, implicit $exec
+    ; RPD-NEXT: 0     1
+    ; RPD-NEXT: 0     2      %1:vgpr_32 = V_MOV_B32_e32 %0:vgpr_32, implicit $exec
+    ; RPD-NEXT: 0     1
+    ; RPD-NEXT: 0     1      S_NOP 0, implicit %1:vgpr_32
+    ; RPD-NEXT: 0     0
+    ; RPD-NEXT: Live-out:
+    %0:vgpr_32 = V_MOV_B32_e32 42, implicit $exec
+    %1:vgpr_32 = V_MOV_B32_e32 %0, implicit $exec
+    S_NOP 0, implicit %1
+...



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