[llvm] [RISCV][GISel] Support select vx, vf form rvv intrinsics (PR #157398)

[Matt Arsenault via llvm-commits]

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@@ -500,6 +500,34 @@ RISCVRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
       OpdsMapping[1] = GPRValueMapping;
     break;
   }
+  case TargetOpcode::G_INTRINSIC: {
+    Intrinsic::ID IntrinsicID = cast<GIntrinsic>(MI).getIntrinsicID();
+
+    if (auto *II = RISCVVIntrinsicsTable::getRISCVVIntrinsicInfo(IntrinsicID)) {
+      unsigned ScalarIdx = -1;
+      if (II->hasScalarOperand()) {
+        ScalarIdx = II->ScalarOperand + 2;
+      }
+      for (unsigned Idx = 0; Idx < NumOperands; ++Idx) {
+        auto &MO = MI.getOperand(Idx);
+        if (!MO.isReg() || !MO.getReg())
+          continue;
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arsenm wrote:

These also probably should not be possible 

https://github.com/llvm/llvm-project/pull/157398