fallback: legalize: G_LSHR <16 x s16>

Run:explore-bc8218b282-20261015-075519
Kind:fallback
Category:legalize: G_LSHR <16 x s16>
Occurrences:2 in 2 configs, 1 test files
Snippet from:umulh.ll @umulh_v16i8 via llvm-extract
Config:-mtriple=riscv32 -mattr=+m
Local check:reproduces at bc8218b282
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

; Function Attrs: nounwind
define <16 x i8> @umulh_v16i8(<16 x i8> %x, <16 x i8> %y) #0 {
  %r = call <16 x i8> @llvm.umulh.v16i8(<16 x i8> %x, <16 x i8> %y)
  ret <16 x i8> %r
}

; Function Attrs: nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none)
declare <16 x i8> @llvm.umulh.v16i8(<16 x i8>, <16 x i8>) #1

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

Reproduce:

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

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %73:_(<16 x s16>) = G_LSHR %70:_, %72:_(<16 x s16>) (in function: umulh_v16i8)
warning: Instruction selection used fallback path for umulh_v16i8

Occurrences (2):

InputFunctionConfig
umulh.llumulh_v16i8-mtriple=riscv32 -mattr=+m
umulh.llumulh_v16i8-mtriple=riscv64 -mattr=+m

Generated 2026-10-15 08:05 UTC.