[llvm] [RISCV][GISEL] instruction-select for G_SPLAT_VECTOR (PR #111193)

[Tobias Stadler via llvm-commits]

tobias-stadler wrote:

> I don't follow. SelectionDAG is turning ISD::SPLAT_VECTOR into RISCVISD::VMV_V_X_VL or RISCVISD::VFMV_V_X_VL. We're never matching selected opcodes.

I'm talking about this:

> We have patterns to fold vector arithmetic with a splat operand into special instructions too. Those patterns expect G_VMV_V_X_VL/G_VFMV_V_F_VL

What I meant is that, I think we should prefer matching generic opcodes like SPLAT_VECTOR in the arithmetic patterns (like you suggested) rather than matching the generic target-specifc opcodes. sorry for not phrasing this clearly.

https://github.com/llvm/llvm-project/pull/111193