fallback: legalize: G

fallback: legalize: G_SUB <4 x s32>

Run:	explore-bc8218b282-20261015-075519
Kind:	fallback
Category:	legalize: G_SUB <4 x s32> NEW
Occurrences:	12 in 12 configs, 4 test files
Snippet from:	zbb-cmp-combine.d8e310ec95.ll (mutant of zbb-cmp-combine.ll) @ugo via llvm-extract + llvm-reduce
Config:	`-mtriple=riscv64 -mattr=+zbb -O3`
Local check:	reproduces at bc8218b282
Compiler Explorer:	https://godbolt.org/z/86K9T9aj4 (llc-assertions-trunk, checked 2026-10-15 08:05 UTC): G reproduces

Snippet:

define <4 x i32> @ugo(<4 x i32> %LGV) {
  %B = urem <4 x i32> %LGV, splat (i32 42)
  ret <4 x i32> %B
}

Compiler Explorer panes:

Pane	Options	Exit	Insts	stderr
GlobalISel	`-mtriple=riscv64 -mattr=+zbb -O3 -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.*`	0	39	remark: <unknown>:0:0: unable to legalize instruction: %21:_(<4 x s32>) = G_SUB %0:_, %20:_ (in function: ugo) warning: Instruction selection used fallback path for ugo
SelectionDAG (control)	`-mtriple=riscv64 -mattr=+zbb -O3 -global-isel=0`	0	39	-

Reproduce:

llc -mtriple=riscv64 -mattr=+zbb -O3 -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv64 -mattr=+zbb -O3 -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %21:_(<4 x s32>) = G_SUB %0:_, %20:_ (in function: ugo)
warning: Instruction selection used fallback path for ugo

Occurrences (12):

Input	Function	Config
double-br-fcmp.157f68f26f.ll (mutant of double-br-fcmp.ll)	br_fcmp_ord	`-mtriple=riscv64 -mattr=+d -verify-machineinstrs -target-abi=lp64d`
double-br-fcmp.35a64f2dcd.ll (mutant of double-br-fcmp.ll)	br_fcmp_ord	`-mtriple=riscv32 -mattr=+zdinx -verify-machineinstrs -target-abi=ilp32`
double-br-fcmp.3bffb87f2d.ll (mutant of double-br-fcmp.ll)	br_fcmp_ord	`-mtriple=riscv64 -mattr=+zdinx -verify-machineinstrs -target-abi=lp64`
double-br-fcmp.88b1e347c0.ll (mutant of double-br-fcmp.ll)	br_fcmp_ord	`-mtriple=riscv32 -mattr=+d -verify-machineinstrs -target-abi=ilp32d`
fold-mem-offset-zilsd.076e8762fb.ll (mutant of fold-mem-offset-zilsd.ll)	test_sh3add_load_minsize	`-mtriple=riscv32 -mattr=+zilsd,+zba`
fold-mem-offset-zilsd.4bd6b7ea39.ll (mutant of fold-mem-offset-zilsd.ll)	test_sh3add_load_minsize	`-mtriple=riscv32 -mattr=+zilsd`
half-br-fcmp.26300a6a3d.ll (mutant of half-br-fcmp.ll)	br_fcmp_ord	`-mtriple=riscv32 -mattr=+zfh -verify-machineinstrs -target-abi ilp32f`
half-br-fcmp.31eb7402c1.ll (mutant of half-br-fcmp.ll)	br_fcmp_ord	`-mtriple=riscv64 -mattr=+zfh -verify-machineinstrs -target-abi lp64f`
half-br-fcmp.513a70cd84.ll (mutant of half-br-fcmp.ll)	br_fcmp_ord	`-mtriple=riscv32 -mattr=+zfhmin -verify-machineinstrs -target-abi ilp32f`
half-br-fcmp.8deb9fd360.ll (mutant of half-br-fcmp.ll)	br_fcmp_ord	`-mtriple=riscv64 -mattr=+zfhmin -verify-machineinstrs -target-abi lp64f`
zbb-cmp-combine.d8e310ec95.ll (mutant of zbb-cmp-combine.ll)	ugo	`-mtriple=riscv64 -mattr=+zbb -O3`
zbb-cmp-combine.ea6cc45056.ll (mutant of zbb-cmp-combine.ll)	ugo	`-mtriple=riscv64 -mattr=+zbb,+f -target-abi=lp64f -O3`

Generated 2026-10-15 08:05 UTC.