[llvm] [RISCV][GISEL] Legalize and post-legalize lower G_INSERT_SUBVECTOR (PR #108859)

[Thorsten Schütt via llvm-commits]

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@@ -915,6 +928,150 @@ bool RISCVLegalizerInfo::legalizeSplatVector(MachineInstr &MI,
   return true;
 }
 
+/// Lowers G_INSERT_SUBVECTOR. We know we can lower it here since the legalizer
+/// marked it as legal.
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tschuett wrote:

It is not marked legal. You marked it as custom.

https://github.com/llvm/llvm-project/pull/108859