fallback: legalize: G_SMULH <2 x s128>

Run:explore-04ca53e65f-20261014-114124
Kind:fallback
Category:legalize: G_SMULH <2 x s128>
Occurrences:2 in 2 configs, 1 test files
Snippet from:smulh.ll @smulh_v2i128 via llvm-extract
Config:-mtriple=riscv32
Local check:reproduces at 04ca53e65f
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

; Function Attrs: nounwind
define <2 x i128> @smulh_v2i128(<2 x i128> %x, <2 x i128> %y) #0 {
  %r = call <2 x i128> @llvm.smulh.v2i128(<2 x i128> %x, <2 x i128> %y)
  ret <2 x i128> %r
}

; Function Attrs: nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none)
declare <2 x i128> @llvm.smulh.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 -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:_(<2 x s128>) = G_SMULH %0:_, %1:_ (in function: smulh_v2i128)
warning: Instruction selection used fallback path for smulh_v2i128

Occurrences (2):

InputFunctionConfig
smulh.llsmulh_v2i128-mtriple=riscv32
smulh.llsmulh_v2i128-mtriple=riscv64

Generated 2026-10-15 08:05 UTC.