[llvm] [RISCV][GISEL] regbankselect for G_SPLAT_VECTOR (PR #110744)

[Craig Topper via llvm-commits]

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@@ -478,6 +478,19 @@ RISCVRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
     }
     break;
   }
+  case TargetOpcode::G_SPLAT_VECTOR: {
+    OpdsMapping[0] = getVRBValueMapping(MRI.getType(MI.getOperand(0).getReg())
+                                            .getSizeInBits()
+                                            .getKnownMinValue());
+
+    LLT ScalarTy = MRI.getType(MI.getOperand(1).getReg());
+    if (GPRSize == 32 && ScalarTy.getSizeInBits() == 64) {
+      assert(MF.getSubtarget<RISCVSubtarget>().hasStdExtD());
+      OpdsMapping[1] = getFPValueMapping(ScalarTy.getSizeInBits());
+    } else
+      OpdsMapping[1] = GPRValueMapping;
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topperc wrote:

This should use `onlyDefinesFP` to get the FPR regbank when possible.

https://github.com/llvm/llvm-project/pull/110744