fallback: legalize: G_UMULH <8 x s8>

Run:explore-bc8218b282-20261015-075519
Kind:fallback
Category:legalize: G_UMULH <8 x s8>
Occurrences:4 in 2 configs, 1 test files
Snippet from:umulh.ll @umulh_v8i8 via llvm-extract
Config:-mtriple=riscv32
Local check:reproduces at bc8218b282
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

; Function Attrs: nounwind
define <8 x i8> @umulh_v8i8(<8 x i8> %x, <8 x i8> %y) #0 {
  %r = call <8 x i8> @llvm.umulh.v8i8(<8 x i8> %x, <8 x i8> %y)
  ret <8 x i8> %r
}

; Function Attrs: nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none)
declare <8 x i8> @llvm.umulh.v8i8(<8 x i8>, <8 x i8>) #1

attributes #0 = { nounwind }
attributes #1 = { nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none) }

Reproduce:

llc -mtriple=riscv32 -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv32 -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %5:_(<8 x s8>) = G_UMULH %0:_, %1:_ (in function: umulh_v8i8)
warning: Instruction selection used fallback path for umulh_v8i8

Occurrences (4):

InputFunctionConfig
umulh.llumulh_v8i8-mtriple=riscv32
umulh.llumulh_v8i8-mtriple=riscv64
umulh.0dd2e02b8b.ll (mutant of umulh.ll)umulh_v8i8-mtriple=riscv32
umulh.a97a119fa3.ll (mutant of umulh.ll)umulh_v8i8-mtriple=riscv64

Generated 2026-10-15 08:05 UTC.