[RISCV][GISEL] Regbank select for scalable vector G_ICMP

Author: michaelmaitland

llvm/lib/CodeGen/RegisterBankInfo.cpp

@@ -484,9 +484,10 @@ void RegisterBankInfo::applyDefaultMapping(const OperandsMapper &OpdMapper) {
       // the storage. However, right now we don't necessarily bump all
       // the types to storage size. For instance, we can consider
       // s16 G_AND legal whereas the storage size is going to be 32.
-      assert(OrigTy.getSizeInBits() <= NewTy.getSizeInBits() &&
-             "Types with difference size cannot be handled by the default "
-             "mapping");
+      assert(
+          TypeSize::isKnownLE(OrigTy.getSizeInBits(), NewTy.getSizeInBits()) &&
+          "Types with difference size cannot be handled by the default "
+          "mapping");
       LLVM_DEBUG(dbgs() << "\nChange type of new opd from " << NewTy << " to "
                         << OrigTy);
       MRI.setType(NewReg, OrigTy);

llvm/lib/Target/RISCV/GISel/RISCVRegisterBankInfo.cpp

@@ -470,6 +470,17 @@ RISCVRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
     OpdsMapping[1] = GPRValueMapping;
     break;
   }
+  case TargetOpcode::G_ICMP: {
+    if (MRI.getType(MI.getOperand(0).getReg()).isVector()) {
+      LLT DstTy = MRI.getType(MI.getOperand(0).getReg());
+      LLT SrcTy = MRI.getType(MI.getOperand(2).getReg());
+      OpdsMapping[0] =
+          getVRBValueMapping(DstTy.getSizeInBits().getKnownMinValue());
+      OpdsMapping[2] = OpdsMapping[3] =
+          getVRBValueMapping(SrcTy.getSizeInBits().getKnownMinValue());
+    }
+    break;
+  }
   case TargetOpcode::G_FCMP: {
     LLT Ty = MRI.getType(MI.getOperand(2).getReg());