[llvm] [RISCV][GISEL] legalize, regbankselect, and instruction-select for G_… (PR #73061)

[Matt Arsenault via llvm-commits]

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@@ -353,6 +353,34 @@ RISCVRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
     OpdsMapping[2] = OpdsMapping[3] = getFPValueMapping(Size);
     break;
   }
+  case TargetOpcode::G_MERGE_VALUES: {
+    // Use FPR64 for s64 merge on rv32.
+    assert(MI.getNumOperands() == 3 && "Unsupported G_MERGE_VALUES");
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arsenm wrote:

This should be implied by the legality rules, which is already implied by an assertion before regbankselect begins 

https://github.com/llvm/llvm-project/pull/73061