Revert "[RISCV] Store only VNInfo val no in VSETVLIInfo. NFC"

As noted in
llvm#93796 (comment),
a better way to teach RISCVInsertVSETVLI to work without LiveIntervals
is to set VNInfo to nullptr and teach the various methods to handle it.
We should try that approach first, so we no longer need this pre-commit
patch.

This reverts commit 4b4d366.

llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp

@@ -504,7 +504,7 @@ DemandedFields getDemanded(const MachineInstr &MI, const RISCVSubtarget *ST) {
 class VSETVLIInfo {
   struct AVLDef {
     // Every AVLDef should have a VNInfo.
-    unsigned ValNo;
+    const VNInfo *ValNo;
     Register DefReg;
   };
   union {
@@ -543,9 +543,9 @@ class VSETVLIInfo {
   void setUnknown() { State = Unknown; }
   bool isUnknown() const { return State == Unknown; }
 
-  void setAVLRegDef(unsigned ValNo, Register AVLReg) {
-    assert(AVLReg.isVirtual());
-    AVLRegDef.ValNo = ValNo;
+  void setAVLRegDef(const VNInfo *VNInfo, Register AVLReg) {
+    assert(VNInfo && AVLReg.isVirtual());
+    AVLRegDef.ValNo = VNInfo;
     AVLRegDef.DefReg = AVLReg;
     State = AVLIsReg;
   }
@@ -571,7 +571,7 @@ class VSETVLIInfo {
     assert(hasAVLImm());
     return AVLImm;
   }
-  unsigned getAVLValNo() const {
+  const VNInfo *getAVLVNInfo() const {
     assert(hasAVLReg());
     return AVLRegDef.ValNo;
   }
@@ -580,10 +580,8 @@ class VSETVLIInfo {
   // boundary slot.
   const MachineInstr *getAVLDefMI(const LiveIntervals *LIS) const {
     assert(hasAVLReg());
-    const VNInfo *VNI =
-        LIS->getInterval(getAVLReg()).getValNumInfo(getAVLValNo());
-    auto *MI = LIS->getInstructionFromIndex(VNI->def);
-    assert(!(VNI->isPHIDef() && MI));
+    auto *MI = LIS->getInstructionFromIndex(getAVLVNInfo()->def);
+    assert(!(getAVLVNInfo()->isPHIDef() && MI));
     return MI;
   }
 
@@ -592,7 +590,7 @@ class VSETVLIInfo {
     if (Info.isUnknown())
       setUnknown();
     else if (Info.hasAVLReg())
-      setAVLRegDef(Info.getAVLValNo(), Info.getAVLReg());
+      setAVLRegDef(Info.getAVLVNInfo(), Info.getAVLReg());
     else if (Info.hasAVLVLMAX())
       setAVLVLMAX();
     else if (Info.hasAVLIgnored())
@@ -631,7 +629,7 @@ class VSETVLIInfo {
 
   bool hasSameAVL(const VSETVLIInfo &Other) const {
     if (hasAVLReg() && Other.hasAVLReg())
-      return getAVLValNo() == Other.getAVLValNo() &&
+      return getAVLVNInfo()->id == Other.getAVLVNInfo()->id &&
              getAVLReg() == Other.getAVLReg();
 
     if (hasAVLImm() && Other.hasAVLImm())
@@ -935,7 +933,7 @@ RISCVInsertVSETVLI::getInfoForVSETVLI(const MachineInstr &MI) const {
     if (AVLReg == RISCV::X0)
       NewInfo.setAVLVLMAX();
     else if (VNInfo *VNI = getVNInfoFromReg(AVLReg, MI, LIS))
-      NewInfo.setAVLRegDef(VNI->id, AVLReg);
+      NewInfo.setAVLRegDef(VNI, AVLReg);
     else {
       assert(MI.getOperand(1).isUndef());
       NewInfo.setAVLIgnored();
@@ -1011,7 +1009,7 @@ RISCVInsertVSETVLI::computeInfoForInstr(const MachineInstr &MI) const {
       else
         InstrInfo.setAVLImm(Imm);
     } else if (VNInfo *VNI = getVNInfoFromReg(VLOp.getReg(), MI, LIS)) {
-      InstrInfo.setAVLRegDef(VNI->id, VLOp.getReg());
+      InstrInfo.setAVLRegDef(VNI, VLOp.getReg());
     } else {
       assert(VLOp.isUndef());
       InstrInfo.setAVLIgnored();
@@ -1262,7 +1260,7 @@ void RISCVInsertVSETVLI::transferAfter(VSETVLIInfo &Info,
     auto &LI = LIS->getInterval(MI.getOperand(1).getReg());
     SlotIndex SI = LIS->getSlotIndexes()->getInstructionIndex(MI).getRegSlot();
     VNInfo *VNI = LI.getVNInfoAt(SI);
-    Info.setAVLRegDef(VNI->id, MI.getOperand(1).getReg());
+    Info.setAVLRegDef(VNI, MI.getOperand(1).getReg());
     return;
   }
 
@@ -1357,8 +1355,7 @@ bool RISCVInsertVSETVLI::needVSETVLIPHI(const VSETVLIInfo &Require,
     return true;
 
   // We need the AVL to have been produced by a PHI node in this basic block.
-  const VNInfo *Valno = LIS->getInterval(Require.getAVLReg())
-                            .getValNumInfo(Require.getAVLValNo());
+  const VNInfo *Valno = Require.getAVLVNInfo();
   if (!Valno->isPHIDef() || LIS->getMBBFromIndex(Valno->def) != &MBB)
     return true;
 
@@ -1522,8 +1519,7 @@ void RISCVInsertVSETVLI::doPRE(MachineBasicBlock &MBB) {
   // we need to prove the value is available at the point we're going
   // to insert the vsetvli at.
   if (AvailableInfo.hasAVLReg()) {
-    const LiveInterval &LI = LIS->getInterval(AvailableInfo.getAVLReg());
-    SlotIndex SI = LI.getValNumInfo(AvailableInfo.getAVLValNo())->def;
+    SlotIndex SI = AvailableInfo.getAVLVNInfo()->def;
     // This is an inline dominance check which covers the case of
     // UnavailablePred being the preheader of a loop.
     if (LIS->getMBBFromIndex(SI) != UnavailablePred)