fallback: legalize: G_UREM <2 x s64>

Snippet:

@G = external global <2 x i64>

; Function Attrs: nounwind
define void @commutative_clmulr_v2i64(<2 x i64> %x, <2 x i64> %y, ptr %p0, ptr %p1) #0 {
  %LGV = load <2 x i64>, ptr @G, align 16
  %x.ext = zext <2 x i64> %x to <2 x i128>
  %y.ext = zext <2 x i64> %y to <2 x i128>
  %clmul_yx = call <2 x i128> @llvm.clmul.v2i128(<2 x i128> %y.ext, <2 x i128> %x.ext)
  %clmul_yx_lshr = lshr <2 x i128> %clmul_yx, splat (i128 63)
  %B = urem <2 x i64> %x, %LGV
  %clmulh_yx = trunc <2 x i128> %clmul_yx_lshr to <2 x i64>
  store <2 x i64> %B, ptr %p0, align 16
  store <2 x i64> %clmulh_yx, ptr %p1, align 16
  ret void
}

; Function Attrs: nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none)
declare <2 x i128> @llvm.clmul.v2i128(<2 x i128>, <2 x i128>) #1

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

Reproduce:

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

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %14:_(<2 x s64>) = G_UREM %0:_, %6:_ (in function: commutative_clmulr_v2i64)
warning: Instruction selection used fallback path for commutative_clmulr_v2i64

Occurrences (8):

Generated 2026-10-15 08:05 UTC.