fallback: legalize: G_UNMERGE_VALUES <2 x s16>,<4 x s16>

Run:main-bc8218b282-20261015-074651
Kind:fallback
Category:legalize: G_UNMERGE_VALUES <2 x s16>,<4 x s16>
Occurrences:4 in 1 configs, 2 test files
Snippet from:rvp-widening-convert.ll @test_pwcvt_v2i16 via llvm-extract
Config:-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
Local check:reproduces at bc8218b282
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

define <2 x i32> @test_pwcvt_v2i16(<2 x i16> %a) {
  %res = sext <2 x i16> %a to <2 x i32>
  ret <2 x i32> %res
}

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: %0:_(<2 x s16>), %2:_(<2 x s16>) = G_UNMERGE_VALUES %1:_(<4 x s16>) (in function: test_pwcvt_v2i16)
warning: Instruction selection used fallback path for test_pwcvt_v2i16

Occurrences (4):

InputFunctionConfig
rvp-simd-64.lltest_zext_v2i16_to_v2i32-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-simd-64.lltest_sext_v2i16_to_v2i32-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-widening-convert.lltest_pwcvt_v2i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-widening-convert.lltest_pwcvtu_v2i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs

Generated 2026-10-15 08:05 UTC.