tree 5e559c174eaafda9134d5dfb3cf9850872819de5
parent b03aa291b8ddc962ff82859b5317d8ea8a7a3e87
author Philip Reames <preames@rivosinc.com> 1744339504 -0700
committer GitHub <noreply@github.com> 1744339504 -0700
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[RISCV] Lower a shuffle which is nearly identity except one replicated element (#135292)

This can be done with a vrgather.vi/vx, and (possibly) a register move.
The alternative is to do a vrgather.vv with a full width index vector.

We'd already caught the two operands forms of this shuffle; this patch
specifically handles the single operand form.

Unfortunately only in abstract, it would be nice if we canonicalized
shuffles in some way wouldn't it?