[llvm] [RISCV] Use RISCVII::getVecPolicyOpNum instead of making assumptions. NFC (PR #144175)

[Craig Topper via llvm-commits]

https://github.com/topperc created https://github.com/llvm/llvm-project/pull/144175

None

>From 6fad389a5206b813f27795857899c4b350e4a374 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Fri, 13 Jun 2025 18:04:32 -0700
Subject: [PATCH] [RISCV] Use RISCVII::getVecPolicyOpNum instead of making
 assumptions. NFC

---
 llvm/lib/Target/RISCV/RISCVInstrInfo.cpp | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index e5d29e1a8b476..0c4069c062ca8 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -3696,7 +3696,8 @@ bool RISCVInstrInfo::findCommutedOpIndices(const MachineInstr &MI,
   case CASE_VMA_OPCODE_LMULS(NMSAC, VV): {
     // If the tail policy is undisturbed we can't commute.
     assert(RISCVII::hasVecPolicyOp(MI.getDesc().TSFlags));
-    if ((MI.getOperand(MI.getNumExplicitOperands() - 1).getImm() & 1) == 0)
+    if ((MI.getOperand(RISCVII::getVecPolicyOpNum(MI.getDesc())).getImm() &
+         1) == 0)
       return false;
 
     // For these instructions we can only swap operand 1 and operand 3 by
@@ -3716,7 +3717,8 @@ bool RISCVInstrInfo::findCommutedOpIndices(const MachineInstr &MI,
   case CASE_VMA_OPCODE_LMULS(NMSUB, VV): {
     // If the tail policy is undisturbed we can't commute.
     assert(RISCVII::hasVecPolicyOp(MI.getDesc().TSFlags));
-    if ((MI.getOperand(MI.getNumExplicitOperands() - 1).getImm() & 1) == 0)
+    if ((MI.getOperand(RISCVII::getVecPolicyOpNum(MI.getDesc())).getImm() &
+         1) == 0)
       return false;
 
     // For these instructions we have more freedom. We can commute with the
@@ -4331,7 +4333,8 @@ MachineInstr *RISCVInstrInfo::convertToThreeAddress(MachineInstr &MI,
     // If the tail policy is undisturbed we can't convert.
     assert(RISCVII::hasVecPolicyOp(MI.getDesc().TSFlags) &&
            MI.getNumExplicitOperands() == 6);
-    if ((MI.getOperand(5).getImm() & 1) == 0)
+    if ((MI.getOperand(RISCVII::getVecPolicyOpNum(MI.getDesc())).getImm() &
+         1) == 0)
       return nullptr;
 
     // clang-format off