fallback: legalize: G

fallback: legalize: G_UMULH s32

Run:	explore-bc8218b282-20261015-075519
Kind:	fallback
Category:	legalize: G_UMULH s32
Occurrences:	22 in 4 configs, 5 test files
Snippet from:	div.ll @udiv_constant via llvm-extract
Config:	`-mtriple=riscv64 -verify-machineinstrs`
Local check:	reproduces at bc8218b282
Compiler Explorer:	not uploaded (over --godbolt-limit or disabled)

Snippet:

; Function Attrs: nounwind
define i32 @udiv_constant(i32 %a) #0 {
  %1 = udiv i32 %a, 5
  ret i32 %1
}

attributes #0 = { nounwind }

Reproduce:

llc -mtriple=riscv64 -verify-machineinstrs -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv64 -verify-machineinstrs -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %9:_(s32) = G_UMULH %0:_, %6:_ (in function: udiv_constant)
warning: Instruction selection used fallback path for udiv_constant

Occurrences (22):

Input	Function	Config
div.ll	udiv_constant	`-mtriple=riscv64 -verify-machineinstrs`
umulh.ll	umulh_i32	`-mtriple=riscv64`
urem-lkk.ll	fold_urem_positive_odd	`-mtriple=riscv64 -verify-machineinstrs`
urem-lkk.ll	fold_urem_positive_even	`-mtriple=riscv64 -verify-machineinstrs`
urem.ll	fold_urem_constants	`-mtriple=riscv64 -verify-machineinstrs`
urem.ll	dont_fold_urem_constants	`-mtriple=riscv64 -verify-machineinstrs`
urem.ll	dont_fold_urem_srem_mixed_constants	`-mtriple=riscv64 -verify-machineinstrs`
urem.ll	dont_fold_srem_urem_mixed_constants	`-mtriple=riscv64 -verify-machineinstrs`
bswap-bitreverse.95794f3e61.ll (mutant of bswap-bitreverse.ll)	pr55484	`-mtriple=riscv64 -mattr=+zbkb -verify-machineinstrs`
bswap-bitreverse.df21506dca.ll (mutant of bswap-bitreverse.ll)	pr55484	`-mtriple=riscv64 -verify-machineinstrs`
bswap-bitreverse.e7aa087e72.ll (mutant of bswap-bitreverse.ll)	pr55484	`-mtriple=riscv64 -mattr=+zbb -verify-machineinstrs`
div.c92b51f980.ll (mutant of div.ll)	udiv_constant	`-mtriple=riscv64 -verify-machineinstrs`
urem-lkk.2f9bbf503b.ll (mutant of urem-lkk.ll)	fold_urem_positive_even	`-mtriple=riscv64 -verify-machineinstrs`
urem-lkk.95c893dbab.ll (mutant of urem-lkk.ll)	fold_urem_positive_odd	`-mtriple=riscv64 -verify-machineinstrs`
urem.05ffb96507.ll (mutant of urem.ll)	dont_fold_urem_constants	`-mtriple=riscv64 -verify-machineinstrs`
urem.05ffb96507.ll (mutant of urem.ll)	dont_fold_srem_urem_mixed_constants	`-mtriple=riscv64 -verify-machineinstrs`
urem.0996c9792a.ll (mutant of urem.ll)	dont_fold_urem_srem_mixed_constants	`-mtriple=riscv64 -verify-machineinstrs`
urem.0996c9792a.ll (mutant of urem.ll)	dont_fold_srem_urem_mixed_constants	`-mtriple=riscv64 -verify-machineinstrs`
urem.5e9f2ab817.ll (mutant of urem.ll)	fold_urem_constants	`-mtriple=riscv64 -verify-machineinstrs`
urem.5e9f2ab817.ll (mutant of urem.ll)	dont_fold_urem_srem_mixed_constants	`-mtriple=riscv64 -verify-machineinstrs`
urem.7eec67a016.ll (mutant of urem.ll)	dont_fold_urem_constants	`-mtriple=riscv64 -verify-machineinstrs`
urem.7eec67a016.ll (mutant of urem.ll)	dont_fold_urem_srem_mixed_constants	`-mtriple=riscv64 -verify-machineinstrs`

Generated 2026-10-15 08:05 UTC.