fallback: legalize: G_LSHR <4 x s64>

Snippet:

; Function Attrs: nounwind
define <4 x i32> @umulh_v4i32(<4 x i32> %x, <4 x i32> %y) #0 {
  %r = call <4 x i32> @llvm.umulh.v4i32(<4 x i32> %x, <4 x i32> %y)
  ret <4 x i32> %r
}

; Function Attrs: nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none)
declare <4 x i32> @llvm.umulh.v4i32(<4 x i32>, <4 x i32>) #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: %21:_(<4 x s64>) = G_LSHR %18:_, %20:_(<4 x s64>) (in function: umulh_v4i32)
warning: Instruction selection used fallback path for umulh_v4i32

Occurrences (2):

Generated 2026-10-15 08:05 UTC.