[AMDGPU] Use common allUsesAvailableAt implementation [nfc] (llvm#161418)

Replace the target specific copy with a call to the generic routine. I
don't spot any differences by eye, and there's nothing in the original
review discussion (llvm#124327) which makes it clear why this was
duplicated.

Author: preames

llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp

@@ -29,6 +29,7 @@
 #include "SIMachineFunctionInfo.h"
 #include "Utils/AMDGPUBaseInfo.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/CalcSpillWeights.h"
 #include "llvm/CodeGen/RegisterClassInfo.h"
 #include "llvm/MC/LaneBitmask.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -1633,64 +1634,6 @@ void GCNSchedStage::revertScheduling() {
   DAG.Regions[RegionIdx] = std::pair(DAG.RegionBegin, DAG.RegionEnd);
 }
 
-bool PreRARematStage::allUsesAvailableAt(const MachineInstr *InstToRemat,
-                                         SlotIndex OriginalIdx,
-                                         SlotIndex RematIdx) const {
-
-  LiveIntervals *LIS = DAG.LIS;
-  MachineRegisterInfo &MRI = DAG.MRI;
-  OriginalIdx = OriginalIdx.getRegSlot(true);
-  RematIdx = std::max(RematIdx, RematIdx.getRegSlot(true));
-  for (const MachineOperand &MO : InstToRemat->operands()) {
-    if (!MO.isReg() || !MO.getReg() || !MO.readsReg())
-      continue;
-
-    if (!MO.getReg().isVirtual()) {
-      // Do not attempt to reason about PhysRegs
-      // TODO: better analysis of PhysReg livness
-      if (!DAG.MRI.isConstantPhysReg(MO.getReg()) &&
-          !DAG.TII->isIgnorableUse(MO))
-        return false;
-
-      // Constant PhysRegs and IgnorableUses are okay
-      continue;
-    }
-
-    LiveInterval &LI = LIS->getInterval(MO.getReg());
-    const VNInfo *OVNI = LI.getVNInfoAt(OriginalIdx);
-    assert(OVNI);
-
-    // Don't allow rematerialization immediately after the original def.
-    // It would be incorrect if InstToRemat redefines the register.
-    // See PR14098.
-    if (SlotIndex::isSameInstr(OriginalIdx, RematIdx))
-      return false;
-
-    if (OVNI != LI.getVNInfoAt(RematIdx))
-      return false;
-
-    // Check that subrange is live at RematIdx.
-    if (LI.hasSubRanges()) {
-      const TargetRegisterInfo *TRI = MRI.getTargetRegisterInfo();
-      unsigned SubReg = MO.getSubReg();
-      LaneBitmask LM = SubReg ? TRI->getSubRegIndexLaneMask(SubReg)
-                              : MRI.getMaxLaneMaskForVReg(MO.getReg());
-      for (LiveInterval::SubRange &SR : LI.subranges()) {
-        if ((SR.LaneMask & LM).none())
-          continue;
-        if (!SR.liveAt(RematIdx))
-          return false;
-
-        // Early exit if all used lanes are checked. No need to continue.
-        LM &= ~SR.LaneMask;
-        if (LM.none())
-          break;
-      }
-    }
-  }
-  return true;
-}
-
 bool PreRARematStage::canIncreaseOccupancyOrReduceSpill() {
   const Function &F = MF.getFunction();
 
@@ -1812,9 +1755,9 @@ bool PreRARematStage::canIncreaseOccupancyOrReduceSpill() {
       // Do not rematerialize an instruction it it uses registers that aren't
       // available at its use. This ensures that we are not extending any live
       // range while rematerializing.
-      SlotIndex DefIdx = DAG.LIS->getInstructionIndex(DefMI);
       SlotIndex UseIdx = DAG.LIS->getInstructionIndex(*UseMI).getRegSlot(true);
-      if (!allUsesAvailableAt(&DefMI, DefIdx, UseIdx))
+      if (!VirtRegAuxInfo::allUsesAvailableAt(&DefMI, UseIdx, *DAG.LIS, DAG.MRI,
+                                              *DAG.TII))
         continue;
 
       REMAT_DEBUG(dbgs() << "Region " << I << ": remat instruction " << DefMI);

llvm/lib/Target/AMDGPU/GCNSchedStrategy.h

@@ -496,12 +496,6 @@ class PreRARematStage : public GCNSchedStage {
   /// stage to their pre-stage values.
   void finalizeGCNSchedStage() override;
 
-  /// \p Returns true if all the uses in \p InstToRemat defined at \p
-  /// OriginalIdx are live at \p RematIdx. This only checks liveness of virtual
-  /// reg uses.
-  bool allUsesAvailableAt(const MachineInstr *InstToRemat,
-                          SlotIndex OriginalIdx, SlotIndex RematIdx) const;
-
 public:
   bool initGCNSchedStage() override;