fallback: legalize: G_SHUFFLE_VECTOR <2 x s16>

Run:main-04ca53e65f-20261014-105623
Kind:fallback
Category:legalize: G_SHUFFLE_VECTOR <2 x s16>
Occurrences:3 in 1 configs, 2 test files
Snippet from:rvp-reverse.ll @test_prev_v2i16 via llvm-extract
Config:-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
Local check:reproduces at 04ca53e65f
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

define <2 x i16> @test_prev_v2i16(<2 x i16> %a) {
  %r = shufflevector <2 x i16> %a, <2 x i16> poison, <2 x i32> <i32 1, i32 0>
  ret <2 x i16> %r
}

Reproduce:

llc -mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %3:_(<2 x s16>) = G_SHUFFLE_VECTOR %0:_(<2 x s16>), %4:_, shufflemask(1, 0) (in function: test_prev_v2i16)
warning: Instruction selection used fallback path for test_prev_v2i16

Occurrences (3):

InputFunctionConfig
rvp-reverse.lltest_prev_v2i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-simd-32.lltest_non_const_splat_i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-reverse.63c57e07bd.ll (mutant of rvp-reverse.ll)test_prev_v2i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs

Generated 2026-10-15 08:05 UTC.