fallback: legalize: G_LSHR <2 x s128>

Run:	main-04ca53e65f-20261014-113325
Kind:	fallback
Category:	legalize: G_LSHR <2 x s128>
Occurrences:	28 in 12 configs, 3 test files
Snippet from:	umulh.ll @umulh_v2i64 via llvm-extract
Config:	`-mtriple=riscv32 -mattr=+m`
Local check:	reproduces at 04ca53e65f
Compiler Explorer:	not uploaded (over --godbolt-limit or disabled)

Snippet:

; Function Attrs: nounwind
define <2 x i64> @umulh_v2i64(<2 x i64> %x, <2 x i64> %y) #0 {
  %r = call <2 x i64> @llvm.umulh.v2i64(<2 x i64> %x, <2 x i64> %y)
  ret <2 x i64> %r
}

; Function Attrs: nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none)
declare <2 x i64> @llvm.umulh.v2i64(<2 x i64>, <2 x i64>) #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: %22:_(<2 x s128>) = G_LSHR %19:_, %21:_(<2 x s128>) (in function: umulh_v2i64)
warning: Instruction selection used fallback path for umulh_v2i64

Occurrences (28):

Input	Function	Config
clmulh.ll	commutative_clmulh_v2i64	`-mtriple=riscv32 -mattr=+m -verify-machineinstrs`
clmulh.ll	commutative_clmulh_v2i64	`-mtriple=riscv32 -mattr=+m,+zbc -verify-machineinstrs`
clmulh.ll	commutative_clmulh_v2i64	`-mtriple=riscv32 -mattr=+m,+zbs -verify-machineinstrs`
clmulh.ll	commutative_clmulh_v2i64	`-mtriple=riscv32 -mattr=+m,+zvbc -verify-machineinstrs`
clmulh.ll	commutative_clmulh_v2i64	`-mtriple=riscv32 -verify-machineinstrs`
clmulh.ll	commutative_clmulh_v2i64	`-mtriple=riscv64 -mattr=+m -verify-machineinstrs`
clmulh.ll	commutative_clmulh_v2i64	`-mtriple=riscv64 -mattr=+m,+zbc -verify-machineinstrs`
clmulh.ll	commutative_clmulh_v2i64	`-mtriple=riscv64 -mattr=+m,+zbs -verify-machineinstrs`
clmulh.ll	commutative_clmulh_v2i64	`-mtriple=riscv64 -mattr=+m,+zvbc -verify-machineinstrs`
clmulh.ll	commutative_clmulh_v2i64	`-mtriple=riscv64 -verify-machineinstrs`
clmulr.ll	commutative_clmulr_v2i64	`-mtriple=riscv32 -mattr=+m -verify-machineinstrs`
clmulr.ll	commutative_clmulr_v2i64	`-mtriple=riscv32 -mattr=+m,+zbc -verify-machineinstrs`
clmulr.ll	commutative_clmulr_v2i64	`-mtriple=riscv32 -mattr=+m,+zbs -verify-machineinstrs`
clmulr.ll	commutative_clmulr_v2i64	`-mtriple=riscv32 -verify-machineinstrs`
clmulr.ll	commutative_clmulr_v2i64	`-mtriple=riscv64 -mattr=+m -verify-machineinstrs`
clmulr.ll	commutative_clmulr_v2i64	`-mtriple=riscv64 -mattr=+m,+zbc -verify-machineinstrs`
clmulr.ll	commutative_clmulr_v2i64	`-mtriple=riscv64 -mattr=+m,+zbs -verify-machineinstrs`
clmulr.ll	commutative_clmulr_v2i64	`-mtriple=riscv64 -verify-machineinstrs`
umulh.ll	umulh_v2i64	`-mtriple=riscv32 -mattr=+m`
umulh.ll	umulh_v2i64	`-mtriple=riscv64 -mattr=+m`
clmulr.2abb38c99f.ll (mutant of clmulr.ll)	commutative_clmulr_v2i64	`-mtriple=riscv32 -mattr=+m,+zbc -verify-machineinstrs`
clmulr.545159b333.ll (mutant of clmulr.ll)	commutative_clmulr_v2i64	`-mtriple=riscv64 -mattr=+m -verify-machineinstrs`
clmulr.74b8995fa6.ll (mutant of clmulr.ll)	commutative_clmulr_v2i64	`-mtriple=riscv64 -mattr=+m,+zbc -verify-machineinstrs`
clmulr.896825ea4c.ll (mutant of clmulr.ll)	commutative_clmulr_v2i64	`-mtriple=riscv64 -mattr=+m,+zbs -verify-machineinstrs`
clmulr.8ac626fabe.ll (mutant of clmulr.ll)	commutative_clmulr_v2i64	`-mtriple=riscv64 -verify-machineinstrs`
clmulr.8d410ac61f.ll (mutant of clmulr.ll)	commutative_clmulr_v2i64	`-mtriple=riscv32 -verify-machineinstrs`
clmulr.bf7a3eb5a8.ll (mutant of clmulr.ll)	commutative_clmulr_v2i64	`-mtriple=riscv32 -mattr=+m -verify-machineinstrs`
clmulr.dd3c03766e.ll (mutant of clmulr.ll)	commutative_clmulr_v2i64	`-mtriple=riscv32 -mattr=+m,+zbs -verify-machineinstrs`

Generated 2026-10-15 08:05 UTC.