[RISCV] CleanupVSETVLI: Add phase to remove redundant VSETVLI instructions across basic blocks

[arcbbb]

Summary

This is a rework from @fpallares's and @rogfer01's patches from BSC.

This patch removes the first VSET[I]VLI from a basic block
when its config is equal to the VL & VType of predecessors.

Authored-by: Ferran Pallarès <[e-mail]>
Authored-by: Roger Ferrer Ibanez <[e-mail]>

[rogfer01]

I'd suggest to add some specific tests showing what this improvement is doing (in addition to the other test changes).

[arcbbb]

address Roger's comment

i. add MIR tests.

[arcbbb]

rebased to pass unit tests.

[frasercrmck]

Sorry I haven't had time to look at this in depth yet. I'll try to get round to it soon.

[arcbbb]

Thank you for reading this.
Because there is an alternative approach proposed by Craig https://reviews.llvm.org/D101938,
I'll check that first and then abandon this when we are in favor of that way.

[arcbbb]

D102739 is the preferred approach.

llvm/lib/Target/RISCV/RISCVCleanupVSETVLI.h

+//===- RISCVCleanupVSETVLI.h - Shared data structures ----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_RISCV_RISCVCLEANUPVSETVLI_H
+#define LLVM_LIB_TARGET_RISCV_RISCVCLEANUPVSETVLI_H
+
+#include "RISCV.h"
+#include "llvm/CodeGen/MachineInstr.h"
+
+namespace llvm {
+
+class VSETVLInstr {
+public:
+  VSETVLInstr() : NewVLReg(0), AVL(0), VType(~0U), Opcode(0) {}
+
+  VSETVLInstr(const MachineInstr &MI)
+      : NewVLReg(MI.getOperand(0).getReg()), VType(MI.getOperand(2).getImm()),
+        Opcode(MI.getOpcode()) {
+    if (Opcode == RISCV::PseudoVSETVLI) {
+      AVL = MI.getOperand(1).getReg();
+    } else {
+      assert(Opcode == RISCV::PseudoVSETIVLI);
+      AVL = MI.getOperand(1).getImm();
+    }
+  }
+
+  Register getNewVLReg() const { return NewVLReg; }
+  void setNewVLReg(Register Reg) { NewVLReg = Reg; }
+
+  bool hasSameConfig(const VSETVLInstr &Other) const {
+    return Opcode == Other.Opcode && AVL == Other.AVL && VType == Other.VType;
+  }
+
+  bool hasSameNewVLReg(const VSETVLInstr &Other) const {
+    return NewVLReg == Other.NewVLReg;
+  }
+
+private:
+  Register NewVLReg;
+  unsigned AVL;
+  unsigned VType;
+  unsigned Opcode;
+};
+
+} // end namespace llvm
+
+#endif

llvm/lib/Target/RISCV/RISCVCleanupVSETVLI.cpp

 //===- RISCVCleanupVSETVLI.cpp - Cleanup unneeded VSETVLI instructions ----===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements a function pass that removes duplicate vsetvli
 // instructions within a basic block.
 //
 //===----------------------------------------------------------------------===//
 
+#include "RISCVCleanupVSETVLI.h"
 #include "RISCV.h"
 #include "RISCVSubtarget.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
+
 using namespace llvm;
 
 #define DEBUG_TYPE "riscv-cleanup-vsetvli"
 #define RISCV_CLEANUP_VSETVLI_NAME "RISCV Cleanup VSETVLI pass"
 
+static cl::opt<bool> DisableCleanupVSETVLGlobal(
+    "riscv-disable-cleanup-vsetvl-global", cl::init(false), cl::Hidden,
+    cl::desc("Disable removing redundant vsetvl global"));
+
 namespace {
 
 class RISCVCleanupVSETVLI : public MachineFunctionPass {
 public:
   static char ID;
 
   RISCVCleanupVSETVLI() : MachineFunctionPass(ID) {
     initializeRISCVCleanupVSETVLIPass(*PassRegistry::getPassRegistry());
if (isRedundantVSETVLI(MI, PrevVSETVLI)) {
       // Otherwise update VSET{I}VLI for the next iteration.
       PrevVSETVLI = &MI;
     }
   }
 
   return Changed;
 }
 
+static bool findLastVSETVLChange(const MachineBasicBlock &MBB,
+                                 VSETVLInstr &VI) {
+  // Instantiate 'Unmatched' value (as per the default constructor).
+  // Unmatched value means that we may observe the effects of different VSETVLI
+  // instructions along different paths that lead to the same program point.
+  const VSETVLInstr Unmatched;
+  for (auto MII = MBB.rbegin(), MIE = MBB.rend(); MII != MIE; ++MII) {
+    if (MII->getOpcode() == RISCV::PseudoVSETVLI ||
+        MII->getOpcode() == RISCV::PseudoVSETIVLI) {
+      // We found a VSET[I]VLI, store it as the output for this block.
+      VI = *MII;
+      return true;
+    } else if (MII->modifiesRegister(RISCV::VL) || MII->isCall()) {
+      // We found some other instruction that modifies VL, mark output as
+      // unmatched.
+      VI = Unmatched;
+      return true;
+    }
+  }
+  return false;
+}
+
+static Optional<VSETVLInstr> collectVIFromPreds(
+    const MachineBasicBlock &MBB,
+    SmallVectorImpl<Optional<VSETVLInstr>> &BBVSETVLInstrOutMap) {
+  const VSETVLInstr Unmatched;
+  Optional<VSETVLInstr> VI;
+  if (MBB.pred_empty()) {
+    // If no predecessors (entry MBB), In[MBB] := Unmatched.
+    // We cannot claim anything about the incoming VSETVLI instruction, so
+    // the only sensible value here is Unmatched. This is the most
+    // conservative value.
+    return Unmatched;
+  }
+  for (const MachineBasicBlock *Pred : MBB.predecessors()) {
+    assert(Pred != nullptr && "Unexpected NULL basic block");
+    Optional<VSETVLInstr> PVI = BBVSETVLInstrOutMap[Pred->getNumber()];
+
+    // VI ∧ Undef = VI.
+    if (!PVI.hasValue())
+      continue;
+
+    if (!VI.hasValue()) {
+      // Undef ∧ VI = VI
+      VI = PVI.getValue();
+      continue;
+    }
+
+    if (!VI->hasSameConfig(*PVI)) {
+      // VI ∧ different VI = Unmatched.
+
+      // Unmatched ∧ * = Unmatched.
+      return Unmatched;
+    }
+
+    if (!VI->hasSameNewVLReg(*PVI)) {
+      // If the config matches, but the NewVL doesn't, clear the NewVL. We
+      // need this for optimizing across PHIs.
+      VI->setNewVLReg(RISCV::NoRegister);
+      // Don't break the loop. We might still have a config mismatch that
+      // needs to reset the AVL/Type.
+    }
+    // else VI ∧ equal VI = VI.
+  }
+  return VI;
+}
+
+static void initBBVSETVLInstrInMap(
+    SmallVectorImpl<Optional<VSETVLInstr>> &BBVSETVLInstrInMap,
+    const MachineFunction &MF) {
+
+  BitVector ModifiesVL(MF.getNumBlockIDs());
+
+  SmallVector<Optional<VSETVLInstr>, 32> BBVSETVLInstrOutMap(
+      MF.getNumBlockIDs());
+
+  // Compute the last VSETVLI instruction found in each basic blocks (if any).
+  for (const MachineBasicBlock &MBB : MF) {
+    VSETVLInstr VI;
+    if (findLastVSETVLChange(MBB, VI)) {
+      ModifiesVL[MBB.getNumber()] = true;
+      BBVSETVLInstrOutMap[MBB.getNumber()] = VI;
+    }
+  }
+
+  SmallVector<const MachineBasicBlock *, 32> Worklist;
+  SmallBitVector InWorkList(MF.getNumBlockIDs(), true);
+
+  for (const MachineBasicBlock &MBB : make_range(MF.rbegin(), MF.rend()))
+    Worklist.push_back(&MBB);
+
+  while (!Worklist.empty()) {
+
+    const MachineBasicBlock &MBB = *Worklist.pop_back_val();
+    InWorkList[MBB.getNumber()] = false;
+
+    Optional<VSETVLInstr> VI = collectVIFromPreds(MBB, BBVSETVLInstrOutMap);
+
+    // In[MBB] == Undef, no updates.
+    if (!VI.hasValue())
+      continue;
+
+    // Update the solution map.
+    BBVSETVLInstrInMap[MBB.getNumber()] = VI.getValue();
+
+    // Apply transfer function over MBB.
+
+    // If there is an explicit VSETVLI instruction in MBB, Out[MBB] is fixed.
+    if (ModifiesVL[MBB.getNumber()])
+      continue;
+
+    // Out[MBB] hasn't changed.
+    if (BBVSETVLInstrOutMap[MBB.getNumber()].hasValue() &&
+        BBVSETVLInstrOutMap[MBB.getNumber()]->hasSameConfig(*VI) &&
+        BBVSETVLInstrOutMap[MBB.getNumber()]->hasSameNewVLReg(*VI))
+      continue;
+
+    // Update Out[MBB] and account for changes.
+    BBVSETVLInstrOutMap[MBB.getNumber()] = VI.getValue();
+    for (auto BBI = MBB.succ_begin(), BBE = MBB.succ_end(); BBI != BBE; ++BBI) {
+      if (!InWorkList[(*BBI)->getNumber()]) {
+        Worklist.push_back(*BBI);
+        InWorkList[(*BBI)->getNumber()] = true;
+      }
+    }
+  }
+}
+
+static bool removeRedundantVSETVLIGlobal(MachineFunction &MF) {
+  bool Changed = false;
+
+  const MachineRegisterInfo &MRI = MF.getRegInfo();
+
+  SmallVector<Optional<VSETVLInstr>, 32> BBVSETVLInstrInMap(
+      MF.getNumBlockIDs());
+
+  initBBVSETVLInstrInMap(BBVSETVLInstrInMap, MF);
+
+  for (MachineBasicBlock &MBB : MF) {
+    Optional<VSETVLInstr> InVI = BBVSETVLInstrInMap[MBB.getNumber()];
+    // Undef shouldn't appear in the solution.
+    assert(InVI.hasValue() && "Unexpected 'Undef' after data flow convergence");
+
+    MachineInstr *FirstVSETVLInstr = nullptr;
+    for (MachineInstr &MI : MBB) {
+      if (MI.getOpcode() == RISCV::PseudoVSETVLI ||
+          MI.getOpcode() == RISCV::PseudoVSETIVLI) {
+        FirstVSETVLInstr = &MI;
+        break;
+      } else if (MI.modifiesRegister(RISCV::VL) || MI.isCall()) {
+        break;
+      }
+    }
+
+    if (!FirstVSETVLInstr)
+      continue;
+
+    LLVM_DEBUG(dbgs() << "Considering removal of \n";
+               FirstVSETVLInstr->dump(););
+
+    VSETVLInstr FirstVI(*FirstVSETVLInstr);
+    Register NewVLReg = FirstVI.getNewVLReg();
+    assert((NewVLReg.isVirtual() || NewVLReg == RISCV::X0) &&
+           "NewVL must be a virtual register or X0!");
+
+    // Don't remove VSETVLI whose NewVL is being used.
+    // FIXME: Replace uses with predecessor's NewVL, using a phi if necessary.
+    if (NewVLReg.isVirtual() && !MRI.use_empty(NewVLReg)) {
+      LLVM_DEBUG(dbgs() << "Not removing because its value is still used.\n";
+                 dbgs() << "Printing uses of defined register "
+                        << printReg(NewVLReg) << "\n";
+                 for (auto UIt = MRI.use_begin(NewVLReg), UEnd = MRI.use_end();
+                      UIt != UEnd; UIt++) {
+                   MachineOperand &MO = *UIt;
+                   MachineInstr *MI = MO.getParent();
+                   MI->dump();
+                 });
+      continue;
+    }
+
+    if (InVI->hasSameConfig(FirstVI)) {
+      LLVM_DEBUG(dbgs() << "Remove redundant VSETVLI instruction leading BB '"
+                        << MBB.getNumber() << "." << MBB.getName() << "':\n";
+                 FirstVSETVLInstr->dump(); dbgs() << "\n");
+      FirstVSETVLInstr->eraseFromParent();
+      Changed = true;
+      continue;
+    }
+  }
+  return Changed;
+}
+
 bool RISCVCleanupVSETVLI::runOnMachineFunction(MachineFunction &MF) {
   if (skipFunction(MF.getFunction()))
     return false;
 
   // Skip if the vector extension is not enabled.
   const RISCVSubtarget &ST = MF.getSubtarget<RISCVSubtarget>();
   if (!ST.hasStdExtV())
     return false;
 
   bool Changed = false;
 
   for (MachineBasicBlock &MBB : MF)
     Changed |= runOnMachineBasicBlock(MBB);
 
+  if (!DisableCleanupVSETVLGlobal)
+    Changed |= removeRedundantVSETVLIGlobal(MF);
+
   return Changed;
 }
 
 /// Returns an instance of the Cleanup VSETVLI pass.
 FunctionPass *llvm::createRISCVCleanupVSETVLIPass() {
   return new RISCVCleanupVSETVLI();
 }

llvm/test/CodeGen/RISCV/rvv/cleanup-vsetvli-global.mir

+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc %s -mtriple=riscv64 -run-pass=riscv-cleanup-vsetvli -o - | FileCheck %s
+
+--- |
+  ; ModuleID = '../llvm/test/CodeGen/RISCV/rvv/add-vsetvli-vlmax.ll'
+  source_filename = "../llvm/test/CodeGen/RISCV/rvv/add-vsetvli-vlmax.ll"
+  target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n64-S128"
+  target triple = "riscv64"
+
+  define void @cleanup_vsetvli_global_1() #0 {
+    ret void
+  }
+
+  define void @cleanup_vsetvli_global_2() #0 {
+    ret void
+  }
+
+  define void @cleanup_vsetvli_global_3() #0 {
+    ret void
+  }
+
+  define void @cleanup_vsetvli_global_4() #0 {
+    ret void
+  }
+
+  attributes #0 = { "target-features"="+experimental-v" }
+
+...
+---
+# Check that one VSETVLI is removed if it matches all coming VSETVLIs from predecessors.
+name:  cleanup_vsetvli_global_1
+alignment:       4
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: cleanup_vsetvli_global_1
+  ; CHECK: bb.0 (%ir-block.0):
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   dead %0:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+  ; CHECK:   PseudoBR %bb.2
+  ; CHECK: bb.1:
+  ; CHECK:   successors: %bb.3(0x80000000)
+  ; CHECK:   dead %1:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+  ; CHECK:   PseudoBR %bb.3
+  ; CHECK: bb.2:
+  ; CHECK:   successors: %bb.3(0x80000000)
+  ; CHECK: bb.3:
+  ; CHECK:   PseudoRET
+  bb.0 (%ir-block.0):
+    dead %0:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+    PseudoBR %bb.2
+  bb.1:
+    dead %10:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+    PseudoBR %bb.3
+  bb.2:
+  bb.3:
+    dead %20:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+    PseudoRET
+...
+---
+# Check that VSETVLI is not removed if the config doesn't match one of its precessors's.
+name:  cleanup_vsetvli_global_2
+alignment:       4
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: cleanup_vsetvli_global_2
+  ; CHECK: bb.0 (%ir-block.0):
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   dead %0:gpr = PseudoVSETIVLI 2, 88, implicit-def $vl, implicit-def $vtype
+  ; CHECK:   PseudoBR %bb.2
+  ; CHECK: bb.1:
+  ; CHECK:   successors: %bb.3(0x80000000)
+  ; CHECK:   dead %1:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+  ; CHECK:   PseudoBR %bb.3
+  ; CHECK: bb.2:
+  ; CHECK:   successors: %bb.3(0x80000000)
+  ; CHECK:   PseudoBR %bb.3
+  ; CHECK: bb.3:
+  ; CHECK:   dead %2:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+  ; CHECK:   PseudoRET
+  bb.0 (%ir-block.0):
+    dead %0:gpr = PseudoVSETIVLI 2, 88, implicit-def $vl, implicit-def $vtype
+    PseudoBR %bb.2
+  bb.1:
+    dead %10:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+    PseudoBR %bb.3
+  bb.2:
+    PseudoBR %bb.3
+  bb.3:
+    dead %20:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+    PseudoRET
+...
+---
+# Check that VSETVLI is not removed if one of predecessors doesn't define VSETVLI.
+name:  cleanup_vsetvli_global_3
+alignment:       4
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: cleanup_vsetvli_global_3
+  ; CHECK: bb.0 (%ir-block.0):
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   PseudoBR %bb.2
+  ; CHECK: bb.1:
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   dead %0:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+  ; CHECK: bb.2:
+  ; CHECK:   dead %1:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+  ; CHECK:   PseudoRET
+  bb.0 (%ir-block.0):
+    PseudoBR %bb.2
+  bb.1:
+    dead %10:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+  bb.2:
+    dead %20:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+    PseudoRET
+...
+---
+# Check that the config doesn't match if it is following a CALL instuction.
+name:  cleanup_vsetvli_global_4
+alignment:       4
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: cleanup_vsetvli_global_4
+  ; CHECK: bb.0 (%ir-block.0):
+  ; CHECK:   successors: %bb.1(0x80000000)
+  ; CHECK:   dead %0:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+  ; CHECK: bb.1:
+  ; CHECK:   PseudoCALL @cleanup_vsetvli_global_4
+  ; CHECK:   dead %1:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+  ; CHECK:   PseudoRET
+  bb.0 (%ir-block.0):
+    dead %0:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+  bb.1:
+    PseudoCALL @cleanup_vsetvli_global_4
+    dead %10:gpr = PseudoVSETIVLI 4, 88, implicit-def $vl, implicit-def $vtype
+    PseudoRET
+...

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-ctlz.ll

 ; LMULMAX2-RV32-NEXT:    add a1, a5, a1
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 4
 ; LMULMAX2-RV32-NEXT:    add a1, a1, a5
 ; LMULMAX2-RV32-NEXT:    and a1, a1, a7
 ; LMULMAX2-RV32-NEXT:    mul a1, a1, a2
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 24
 ; LMULMAX2-RV32-NEXT:  .LBB3_3:
 ; LMULMAX2-RV32-NEXT:    sw a5, 0(sp)
-; LMULMAX2-RV32-NEXT:    vsetivli a1, 1, e64,m1,ta,mu
 ; LMULMAX2-RV32-NEXT:    vslidedown.vi v25, v25, 1
 ; LMULMAX2-RV32-NEXT:    vsrl.vx v26, v25, a6
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a1, v26
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a5, v25
 ; LMULMAX2-RV32-NEXT:    bnez a1, .LBB3_5
 ; LMULMAX2-RV32-NEXT:  # %bb.4:
 ; LMULMAX2-RV32-NEXT:    srli a1, a5, 1
 ; LMULMAX2-RV32-NEXT:    or a1, a5, a1

 ; LMULMAX1-RV32-NEXT:    add a1, a5, a1
 ; LMULMAX1-RV32-NEXT:    srli a5, a1, 4
 ; LMULMAX1-RV32-NEXT:    add a1, a1, a5
 ; LMULMAX1-RV32-NEXT:    and a1, a1, a7
 ; LMULMAX1-RV32-NEXT:    mul a1, a1, a2
 ; LMULMAX1-RV32-NEXT:    srli a5, a1, 24
 ; LMULMAX1-RV32-NEXT:  .LBB3_3:
 ; LMULMAX1-RV32-NEXT:    sw a5, 0(sp)
-; LMULMAX1-RV32-NEXT:    vsetivli a1, 1, e64,m1,ta,mu
 ; LMULMAX1-RV32-NEXT:    vslidedown.vi v25, v25, 1
 ; LMULMAX1-RV32-NEXT:    vsrl.vx v26, v25, a6
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a1, v26
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a5, v25
 ; LMULMAX1-RV32-NEXT:    bnez a1, .LBB3_5
 ; LMULMAX1-RV32-NEXT:  # %bb.4:
 ; LMULMAX1-RV32-NEXT:    srli a1, a5, 1
 ; LMULMAX1-RV32-NEXT:    or a1, a5, a1

 ; LMULMAX2-RV32-NEXT:    add a1, a5, a1
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 4
 ; LMULMAX2-RV32-NEXT:    add a1, a1, a5
 ; LMULMAX2-RV32-NEXT:    and a1, a1, a7
 ; LMULMAX2-RV32-NEXT:    mul a1, a1, a2
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 24
 ; LMULMAX2-RV32-NEXT:  .LBB7_3:
 ; LMULMAX2-RV32-NEXT:    sw a5, 0(sp)
-; LMULMAX2-RV32-NEXT:    vsetivli a1, 1, e64,m2,ta,mu
 ; LMULMAX2-RV32-NEXT:    vslidedown.vi v28, v26, 3
 ; LMULMAX2-RV32-NEXT:    vsrl.vx v30, v28, a6
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a1, v30
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a5, v28
 ; LMULMAX2-RV32-NEXT:    bnez a1, .LBB7_5
 ; LMULMAX2-RV32-NEXT:  # %bb.4:
 ; LMULMAX2-RV32-NEXT:    srli a1, a5, 1
 ; LMULMAX2-RV32-NEXT:    or a1, a5, a1

 ; LMULMAX2-RV32-NEXT:    add a1, a5, a1
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 4
 ; LMULMAX2-RV32-NEXT:    add a1, a1, a5
 ; LMULMAX2-RV32-NEXT:    and a1, a1, a7
 ; LMULMAX2-RV32-NEXT:    mul a1, a1, a2
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 24
 ; LMULMAX2-RV32-NEXT:  .LBB7_6:
 ; LMULMAX2-RV32-NEXT:    sw a5, 24(sp)
-; LMULMAX2-RV32-NEXT:    vsetivli a1, 1, e64,m2,ta,mu
 ; LMULMAX2-RV32-NEXT:    vslidedown.vi v28, v26, 2
 ; LMULMAX2-RV32-NEXT:    vsrl.vx v30, v28, a6
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a1, v30
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a5, v28
 ; LMULMAX2-RV32-NEXT:    bnez a1, .LBB7_8
 ; LMULMAX2-RV32-NEXT:  # %bb.7:
 ; LMULMAX2-RV32-NEXT:    srli a1, a5, 1
 ; LMULMAX2-RV32-NEXT:    or a1, a5, a1

 ; LMULMAX2-RV32-NEXT:    add a1, a5, a1
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 4
 ; LMULMAX2-RV32-NEXT:    add a1, a1, a5
 ; LMULMAX2-RV32-NEXT:    and a1, a1, a7
 ; LMULMAX2-RV32-NEXT:    mul a1, a1, a2
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 24
 ; LMULMAX2-RV32-NEXT:  .LBB7_9:
 ; LMULMAX2-RV32-NEXT:    sw a5, 16(sp)
-; LMULMAX2-RV32-NEXT:    vsetivli a1, 1, e64,m2,ta,mu
 ; LMULMAX2-RV32-NEXT:    vslidedown.vi v26, v26, 1
 ; LMULMAX2-RV32-NEXT:    vsrl.vx v28, v26, a6
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a1, v28
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a5, v26
 ; LMULMAX2-RV32-NEXT:    bnez a1, .LBB7_11
 ; LMULMAX2-RV32-NEXT:  # %bb.10:
 ; LMULMAX2-RV32-NEXT:    srli a1, a5, 1
 ; LMULMAX2-RV32-NEXT:    or a1, a5, a1

 ; LMULMAX1-RV32-NEXT:    add a1, a2, a1
 ; LMULMAX1-RV32-NEXT:    srli a2, a1, 4
 ; LMULMAX1-RV32-NEXT:    add a1, a1, a2
 ; LMULMAX1-RV32-NEXT:    and a1, a1, t0
 ; LMULMAX1-RV32-NEXT:    mul a1, a1, a3
 ; LMULMAX1-RV32-NEXT:    srli a1, a1, 24
 ; LMULMAX1-RV32-NEXT:  .LBB7_3:
 ; LMULMAX1-RV32-NEXT:    sw a1, 16(sp)
-; LMULMAX1-RV32-NEXT:    vsetivli a1, 1, e64,m1,ta,mu
 ; LMULMAX1-RV32-NEXT:    vslidedown.vi v26, v26, 1
 ; LMULMAX1-RV32-NEXT:    vsrl.vx v27, v26, a7
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a1, v27
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a2, v26
 ; LMULMAX1-RV32-NEXT:    bnez a1, .LBB7_5
 ; LMULMAX1-RV32-NEXT:  # %bb.4:
 ; LMULMAX1-RV32-NEXT:    srli a1, a2, 1
 ; LMULMAX1-RV32-NEXT:    or a1, a2, a1

 ; LMULMAX1-RV32-NEXT:    add a1, a2, a1
 ; LMULMAX1-RV32-NEXT:    srli a2, a1, 4
 ; LMULMAX1-RV32-NEXT:    add a1, a1, a2
 ; LMULMAX1-RV32-NEXT:    and a1, a1, t0
 ; LMULMAX1-RV32-NEXT:    mul a1, a1, a3
 ; LMULMAX1-RV32-NEXT:    srli a1, a1, 24
 ; LMULMAX1-RV32-NEXT:  .LBB7_9:
 ; LMULMAX1-RV32-NEXT:    sw a1, 0(sp)
-; LMULMAX1-RV32-NEXT:    vsetivli a1, 1, e64,m1,ta,mu
 ; LMULMAX1-RV32-NEXT:    vslidedown.vi v25, v25, 1
 ; LMULMAX1-RV32-NEXT:    vsrl.vx v26, v25, a7
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a1, v26
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a2, v25
 ; LMULMAX1-RV32-NEXT:    bnez a1, .LBB7_11
 ; LMULMAX1-RV32-NEXT:  # %bb.10:
 ; LMULMAX1-RV32-NEXT:    srli a1, a2, 1
 ; LMULMAX1-RV32-NEXT:    or a1, a2, a1

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-cttz.ll

 ; LMULMAX2-RV32-NEXT:    add a1, a5, a1
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 4
 ; LMULMAX2-RV32-NEXT:    add a1, a1, a5
 ; LMULMAX2-RV32-NEXT:    and a1, a1, a7
 ; LMULMAX2-RV32-NEXT:    mul a1, a1, a2
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 24
 ; LMULMAX2-RV32-NEXT:  .LBB3_3:
 ; LMULMAX2-RV32-NEXT:    sw a5, 0(sp)
-; LMULMAX2-RV32-NEXT:    vsetivli a1, 1, e64,m1,ta,mu
 ; LMULMAX2-RV32-NEXT:    vslidedown.vi v25, v25, 1
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a5, v25
 ; LMULMAX2-RV32-NEXT:    vsrl.vx v25, v25, a6
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a1, v25
 ; LMULMAX2-RV32-NEXT:    bnez a5, .LBB3_5
 ; LMULMAX2-RV32-NEXT:  # %bb.4:
 ; LMULMAX2-RV32-NEXT:    addi a5, a1, -1
 ; LMULMAX2-RV32-NEXT:    not a1, a1

 ; LMULMAX1-RV32-NEXT:    add a1, a5, a1
 ; LMULMAX1-RV32-NEXT:    srli a5, a1, 4
 ; LMULMAX1-RV32-NEXT:    add a1, a1, a5
 ; LMULMAX1-RV32-NEXT:    and a1, a1, a7
 ; LMULMAX1-RV32-NEXT:    mul a1, a1, a2
 ; LMULMAX1-RV32-NEXT:    srli a5, a1, 24
 ; LMULMAX1-RV32-NEXT:  .LBB3_3:
 ; LMULMAX1-RV32-NEXT:    sw a5, 0(sp)
-; LMULMAX1-RV32-NEXT:    vsetivli a1, 1, e64,m1,ta,mu
 ; LMULMAX1-RV32-NEXT:    vslidedown.vi v25, v25, 1
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a5, v25
 ; LMULMAX1-RV32-NEXT:    vsrl.vx v25, v25, a6
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a1, v25
 ; LMULMAX1-RV32-NEXT:    bnez a5, .LBB3_5
 ; LMULMAX1-RV32-NEXT:  # %bb.4:
 ; LMULMAX1-RV32-NEXT:    addi a5, a1, -1
 ; LMULMAX1-RV32-NEXT:    not a1, a1

 ; LMULMAX2-RV32-NEXT:    add a1, a5, a1
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 4
 ; LMULMAX2-RV32-NEXT:    add a1, a1, a5
 ; LMULMAX2-RV32-NEXT:    and a1, a1, a7
 ; LMULMAX2-RV32-NEXT:    mul a1, a1, a2
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 24
 ; LMULMAX2-RV32-NEXT:  .LBB7_3:
 ; LMULMAX2-RV32-NEXT:    sw a5, 0(sp)
-; LMULMAX2-RV32-NEXT:    vsetivli a1, 1, e64,m2,ta,mu
 ; LMULMAX2-RV32-NEXT:    vslidedown.vi v28, v26, 3
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a5, v28
 ; LMULMAX2-RV32-NEXT:    vsrl.vx v28, v28, a6
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a1, v28
 ; LMULMAX2-RV32-NEXT:    bnez a5, .LBB7_5
 ; LMULMAX2-RV32-NEXT:  # %bb.4:
 ; LMULMAX2-RV32-NEXT:    addi a5, a1, -1
 ; LMULMAX2-RV32-NEXT:    not a1, a1

 ; LMULMAX2-RV32-NEXT:    add a1, a5, a1
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 4
 ; LMULMAX2-RV32-NEXT:    add a1, a1, a5
 ; LMULMAX2-RV32-NEXT:    and a1, a1, a7
 ; LMULMAX2-RV32-NEXT:    mul a1, a1, a2
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 24
 ; LMULMAX2-RV32-NEXT:  .LBB7_6:
 ; LMULMAX2-RV32-NEXT:    sw a5, 24(sp)
-; LMULMAX2-RV32-NEXT:    vsetivli a1, 1, e64,m2,ta,mu
 ; LMULMAX2-RV32-NEXT:    vslidedown.vi v28, v26, 2
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a5, v28
 ; LMULMAX2-RV32-NEXT:    vsrl.vx v28, v28, a6
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a1, v28
 ; LMULMAX2-RV32-NEXT:    bnez a5, .LBB7_8
 ; LMULMAX2-RV32-NEXT:  # %bb.7:
 ; LMULMAX2-RV32-NEXT:    addi a5, a1, -1
 ; LMULMAX2-RV32-NEXT:    not a1, a1

 ; LMULMAX2-RV32-NEXT:    add a1, a5, a1
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 4
 ; LMULMAX2-RV32-NEXT:    add a1, a1, a5
 ; LMULMAX2-RV32-NEXT:    and a1, a1, a7
 ; LMULMAX2-RV32-NEXT:    mul a1, a1, a2
 ; LMULMAX2-RV32-NEXT:    srli a5, a1, 24
 ; LMULMAX2-RV32-NEXT:  .LBB7_9:
 ; LMULMAX2-RV32-NEXT:    sw a5, 16(sp)
-; LMULMAX2-RV32-NEXT:    vsetivli a1, 1, e64,m2,ta,mu
 ; LMULMAX2-RV32-NEXT:    vslidedown.vi v26, v26, 1
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a5, v26
 ; LMULMAX2-RV32-NEXT:    vsrl.vx v26, v26, a6
 ; LMULMAX2-RV32-NEXT:    vmv.x.s a1, v26
 ; LMULMAX2-RV32-NEXT:    bnez a5, .LBB7_11
 ; LMULMAX2-RV32-NEXT:  # %bb.10:
 ; LMULMAX2-RV32-NEXT:    addi a5, a1, -1
 ; LMULMAX2-RV32-NEXT:    not a1, a1

 ; LMULMAX1-RV32-NEXT:    add a1, a2, a1
 ; LMULMAX1-RV32-NEXT:    srli a2, a1, 4
 ; LMULMAX1-RV32-NEXT:    add a1, a1, a2
 ; LMULMAX1-RV32-NEXT:    and a1, a1, t0
 ; LMULMAX1-RV32-NEXT:    mul a1, a1, a3
 ; LMULMAX1-RV32-NEXT:    srli a1, a1, 24
 ; LMULMAX1-RV32-NEXT:  .LBB7_3:
 ; LMULMAX1-RV32-NEXT:    sw a1, 16(sp)
-; LMULMAX1-RV32-NEXT:    vsetivli a1, 1, e64,m1,ta,mu
 ; LMULMAX1-RV32-NEXT:    vslidedown.vi v26, v26, 1
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a1, v26
 ; LMULMAX1-RV32-NEXT:    vsrl.vx v26, v26, a7
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a2, v26
 ; LMULMAX1-RV32-NEXT:    bnez a1, .LBB7_5
 ; LMULMAX1-RV32-NEXT:  # %bb.4:
 ; LMULMAX1-RV32-NEXT:    addi a1, a2, -1
 ; LMULMAX1-RV32-NEXT:    not a2, a2

 ; LMULMAX1-RV32-NEXT:    add a1, a2, a1
 ; LMULMAX1-RV32-NEXT:    srli a2, a1, 4
 ; LMULMAX1-RV32-NEXT:    add a1, a1, a2
 ; LMULMAX1-RV32-NEXT:    and a1, a1, t0
 ; LMULMAX1-RV32-NEXT:    mul a1, a1, a3
 ; LMULMAX1-RV32-NEXT:    srli a1, a1, 24
 ; LMULMAX1-RV32-NEXT:  .LBB7_9:
 ; LMULMAX1-RV32-NEXT:    sw a1, 0(sp)
-; LMULMAX1-RV32-NEXT:    vsetivli a1, 1, e64,m1,ta,mu
 ; LMULMAX1-RV32-NEXT:    vslidedown.vi v25, v25, 1
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a1, v25
 ; LMULMAX1-RV32-NEXT:    vsrl.vx v25, v25, a7
 ; LMULMAX1-RV32-NEXT:    vmv.x.s a2, v25
 ; LMULMAX1-RV32-NEXT:    bnez a1, .LBB7_11
 ; LMULMAX1-RV32-NEXT:  # %bb.10:
 ; LMULMAX1-RV32-NEXT:    addi a1, a2, -1
 ; LMULMAX1-RV32-NEXT:    not a2, a2

llvm/test/CodeGen/RISCV/rvv/fixed-vectors-int.ll

 }
 
 define void @extract_v4i64(<4 x i64>* %x, <4 x i64>* %y) {
 ; LMULMAX2-LABEL: extract_v4i64:
 ; LMULMAX2:       # %bb.0:
 ; LMULMAX2-NEXT:    vsetivli a2, 4, e64,m2,ta,mu
 ; LMULMAX2-NEXT:    vle64.v v26, (a0)
 ; LMULMAX2-NEXT:    vle64.v v28, (a1)
-; LMULMAX2-NEXT:    vsetivli a1, 4, e64,m2,ta,mu
 ; LMULMAX2-NEXT:    vadd.vv v26, v26, v28
 ; LMULMAX2-NEXT:    vse64.v v26, (a0)
 ; LMULMAX2-NEXT:    ret
 ;
 ; LMULMAX1-LABEL: extract_v4i64:
 ; LMULMAX1:       # %bb.0:
 ; LMULMAX1-NEXT:    vsetivli a2, 2, e64,m1,ta,mu
 ; LMULMAX1-NEXT:    vle64.v v25, (a0)
 ; LMULMAX1-NEXT:    addi a2, a0, 16
 ; LMULMAX1-NEXT:    vle64.v v26, (a2)
 ; LMULMAX1-NEXT:    vle64.v v27, (a1)
 ; LMULMAX1-NEXT:    addi a1, a1, 16
 ; LMULMAX1-NEXT:    vle64.v v28, (a1)
-; LMULMAX1-NEXT:    vsetivli a1, 2, e64,m1,ta,mu
 ; LMULMAX1-NEXT:    vadd.vv v26, v26, v28
 ; LMULMAX1-NEXT:    vadd.vv v25, v25, v27
 ; LMULMAX1-NEXT:    vse64.v v25, (a0)
 ; LMULMAX1-NEXT:    vse64.v v26, (a2)
 ; LMULMAX1-NEXT:    ret
   %a = load <4 x i64>, <4 x i64>* %x
   %b = load <4 x i64>, <4 x i64>* %y
   br label %"compute"