> Can you explain to me why, exactly, would you ever make jal take a register operand, instead of using a fixed link register and putting the spare bits into the address immediate?
AFAIK, the reason RISC-V supports alternative link registers is that it allows for efficient -msave-restore, keeps the encoding orthogonal to LUI/AUPIC and using the smaller immediate didn't impact codegen much.
AFAIK, the reason RISC-V supports alternative link registers is that it allows for efficient -msave-restore, keeps the encoding orthogonal to LUI/AUPIC and using the smaller immediate didn't impact codegen much.