fallback: legalize: G

fallback: legalize: G_UMULH s8

Run:	main-04ca53e65f-20261014-113325
Kind:	fallback
Category:	legalize: G_UMULH s8
Occurrences:	14 in 10 configs, 3 test files
Snippet from:	div.ll @udiv8_constant via llvm-extract
Config:	`-mtriple=riscv32 -verify-machineinstrs`
Local check:	reproduces at 04ca53e65f
Compiler Explorer:	not uploaded (over --godbolt-limit or disabled)

Snippet:

; Function Attrs: nounwind
define i8 @udiv8_constant(i8 %a) #0 {
  %1 = udiv i8 %a, 5
  ret i8 %1
}

attributes #0 = { nounwind }

Reproduce:

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

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %9:_(s8) = G_UMULH %0:_, %6:_ (in function: udiv8_constant)
warning: Instruction selection used fallback path for udiv8_constant

Occurrences (14):

Input	Function	Config
div.ll	udiv8_constant	`-mtriple=riscv32 -verify-machineinstrs`
div.ll	udiv8_constant	`-mtriple=riscv64 -verify-machineinstrs`
div.25b92cf649.ll (mutant of div.ll)	udiv8_constant	`-mtriple=riscv64 -verify-machineinstrs`
div.e19394eece.ll (mutant of div.ll)	udiv8_constant	`-mtriple=riscv32 -verify-machineinstrs`
emit-x8-as-fp.4b205e108c.ll (mutant of emit-x8-as-fp.ll)	add	`-mtriple=riscv64 -M emit-x8-as-fp -verify-machineinstrs`
emit-x8-as-fp.8f4c70fc09.ll (mutant of emit-x8-as-fp.ll)	add	`-mtriple=riscv32 -M numeric -M emit-x8-as-fp -verify-machineinstrs`
emit-x8-as-fp.a040fd386e.ll (mutant of emit-x8-as-fp.ll)	add	`-mtriple=riscv64 -verify-machineinstrs`
emit-x8-as-fp.b3bc565b32.ll (mutant of emit-x8-as-fp.ll)	add	`-mtriple=riscv32 -M emit-x8-as-fp -verify-machineinstrs`
emit-x8-as-fp.bcca3210ee.ll (mutant of emit-x8-as-fp.ll)	add	`-mtriple=riscv32 -verify-machineinstrs`
emit-x8-as-fp.e11a32cb85.ll (mutant of emit-x8-as-fp.ll)	add	`-mtriple=riscv64 -M numeric -M emit-x8-as-fp -verify-machineinstrs`
prefer-sp-over-fp-with-v.0a0fb8a2a4.ll (mutant of prefer-sp-over-fp-with-v.ll)	foo	`-mtriple=riscv64 -frame-pointer=non-leaf`
prefer-sp-over-fp-with-v.5c770efe4f.ll (mutant of prefer-sp-over-fp-with-v.ll)	foo	`-mtriple=riscv32 -frame-pointer=non-leaf`
prefer-sp-over-fp-with-v.8c187de58d.ll (mutant of prefer-sp-over-fp-with-v.ll)	foo	`-mtriple=riscv32 -mattr=+v -frame-pointer=non-leaf`
prefer-sp-over-fp-with-v.e714ed69f3.ll (mutant of prefer-sp-over-fp-with-v.ll)	foo	`-mtriple=riscv64 -mattr=+v -frame-pointer=non-leaf`

Generated 2026-10-15 08:05 UTC.