fallback: legalize: G_UNMERGE_VALUES <4 x s8>,<8 x s8>

Run:main-bc8218b282-20261015-074651
Kind:fallback
Category:legalize: G_UNMERGE_VALUES <4 x s8>,<8 x s8>
Occurrences:5 in 1 configs, 2 test files
Snippet from:rvp-widening-convert.ll @test_pwcvt_v4i8 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 <4 x i16> @test_pwcvt_v4i8(<4 x i8> %a) {
  %res = sext <4 x i8> %a to <4 x i16>
  ret <4 x i16> %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:_(<4 x s8>), %2:_(<4 x s8>) = G_UNMERGE_VALUES %1:_(<8 x s8>) (in function: test_pwcvt_v4i8)
warning: Instruction selection used fallback path for test_pwcvt_v4i8

Occurrences (5):

InputFunctionConfig
rvp-simd-64.lltest_zext_v4i8_to_v4i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-simd-64.lltest_sext_v4i8_to_v4i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-widening-convert.lltest_pwcvt_v4i8-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-widening-convert.lltest_pwcvtu_v4i8-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-widening-convert.de705c1275.ll (mutant of rvp-widening-convert.ll)test_pwcvt_v4i8-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs

Generated 2026-10-15 08:05 UTC.