Index: llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp =================================================================== --- llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp +++ llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp @@ -202,6 +202,9 @@ } // Check if the VTYPE for these two VSETVLIInfos produce the same VLMAX. + // Note that having the same VLMAX ensures that both share the same + // function from AVL to VL; that is, they must produce the same VL value + // for any given AVL value. bool hasSameVLMAX(const VSETVLIInfo &Other) const { assert(isValid() && Other.isValid() && "Can't compare invalid VSETVLIInfos"); @@ -716,7 +719,7 @@ return false; // We didn't find a compatible value. If our AVL is a virtual register, - // it might be defined by a VSET(I)VLI. If it has the same VTYPE we need + // it might be defined by a VSET(I)VLI. If it has the same VLMAXE we need // and the last VL/VTYPE we observed is the same, we don't need a // VSETVLI here. if (!CurInfo.isUnknown() && Require.hasAVLReg() && @@ -725,7 +728,7 @@ if (MachineInstr *DefMI = MRI->getVRegDef(Require.getAVLReg())) { if (isVectorConfigInstr(*DefMI)) { VSETVLIInfo DefInfo = getInfoForVSETVLI(*DefMI); - if (DefInfo.hasSameAVL(CurInfo) && DefInfo.hasSameVTYPE(CurInfo)) + if (DefInfo.hasSameAVL(CurInfo) && DefInfo.hasSameVLMAX(CurInfo)) return false; } } @@ -1236,7 +1239,7 @@ } } - // If AVL is defined by a vsetvli with the same vtype, we can + // If AVL is defined by a vsetvli with the same vlmax, we can // replace the AVL operand with the AVL of the defining vsetvli. // We avoid general register AVLs to avoid extending live ranges // without being sure we can kill the original source reg entirely. @@ -1245,7 +1248,7 @@ if (MachineInstr *DefMI = MRI->getVRegDef(Require.getAVLReg())) { if (isVectorConfigInstr(*DefMI)) { VSETVLIInfo DefInfo = getInfoForVSETVLI(*DefMI); - if (DefInfo.hasSameVTYPE(Require) && + if (DefInfo.hasSameVLMAX(Require) && (DefInfo.hasAVLImm() || DefInfo.getAVLReg() == RISCV::X0)) { MachineOperand &VLOp = MI.getOperand(getVLOpNum(MI)); if (DefInfo.hasAVLImm()) Index: llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.ll =================================================================== --- llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.ll +++ llvm/test/CodeGen/RISCV/rvv/vsetvli-insert-crossbb.ll @@ -816,7 +816,6 @@ ; CHECK: # %bb.0: # %entry ; CHECK-NEXT: vsetivli a0, 6, e32, m2, tu, mu ; CHECK-NEXT: vmv.s.x v8, a0 -; CHECK-NEXT: vsetvli zero, a0, e32, m2, tu, mu ; CHECK-NEXT: vadd.vv v8, v8, v10, v0.t ; CHECK-NEXT: ret %mask) {