[llvm] [RISCV] Move performCombineVMergeAndVOps into RISCVFoldMasks (PR #71764)

[Wang Pengcheng via llvm-commits]

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@@ -88,6 +107,313 @@ bool RISCVFoldMasks::isAllOnesMask(MachineInstr *MaskCopy) {
   }
 }
 
+static unsigned getVMSetForLMul(RISCVII::VLMUL LMUL) {
+  switch (LMUL) {
+  case RISCVII::LMUL_F8:
+    return RISCV::PseudoVMSET_M_B1;
+  case RISCVII::LMUL_F4:
+    return RISCV::PseudoVMSET_M_B2;
+  case RISCVII::LMUL_F2:
+    return RISCV::PseudoVMSET_M_B4;
+  case RISCVII::LMUL_1:
+    return RISCV::PseudoVMSET_M_B8;
+  case RISCVII::LMUL_2:
+    return RISCV::PseudoVMSET_M_B16;
+  case RISCVII::LMUL_4:
+    return RISCV::PseudoVMSET_M_B32;
+  case RISCVII::LMUL_8:
+    return RISCV::PseudoVMSET_M_B64;
+  case RISCVII::LMUL_RESERVED:
+    llvm_unreachable("Unexpected LMUL");
+  }
+  llvm_unreachable("Unknown VLMUL enum");
+}
+
+/// Inserts an operand at Idx in MI, pushing back any operands.
+static void insertOperand(MachineInstr &MI, MachineOperand MO, unsigned Idx) {
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wangpc-pp wrote:

`MachineInstr::insert` that was added in #67699 may help.

https://github.com/llvm/llvm-project/pull/71764