fallback: legalize: G_SDIV <4 x s32>

Run:	explore-bc8218b282-20261015-075519
Kind:	fallback
Category:	legalize: G_SDIV <4 x s32> NEW
Occurrences:	14 in 10 configs, 7 test files
Snippet from:	alu8.1bcbaf5071.ll (mutant of alu8.ll) @sll via llvm-extract + llvm-reduce
Config:	`-mtriple=riscv32 -verify-machineinstrs`
Local check:	reproduces at bc8218b282
Compiler Explorer:	https://godbolt.org/z/aKnMrcTbG (llc-assertions-trunk, checked 2026-10-15 08:05 UTC): G reproduces

Snippet:

define <4 x i32> @sll() {
  %B = sdiv <4 x i32> splat (i32 1), zeroinitializer
  ret <4 x i32> %B
}

Compiler Explorer panes:

Pane	Options	Exit	Insts	stderr
GlobalISel	`-mtriple=riscv32 -verify-machineinstrs -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.*`	0	1	remark: <unknown>:0:0: unable to legalize instruction: %5:_(<4 x s32>) = G_SDIV %1:_, %3:_ (in function: sll) warning: Instruction selection used fallback path for sll
SelectionDAG (control)	`-mtriple=riscv32 -verify-machineinstrs -global-isel=0`	0	1	-

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: %5:_(<4 x s32>) = G_SDIV %1:_, %3:_ (in function: sll)
warning: Instruction selection used fallback path for sll

Occurrences (14):

Input	Function	Config
alu16.2c5d2191e6.ll (mutant of alu16.ll)	sll	`-mtriple=riscv32 -verify-machineinstrs`
alu16.6816a86a7c.ll (mutant of alu16.ll)	sll	`-mtriple=riscv64 -verify-machineinstrs`
alu8.1bcbaf5071.ll (mutant of alu8.ll)	sll	`-mtriple=riscv32 -verify-machineinstrs`
alu8.4acdc92f42.ll (mutant of alu8.ll)	sll	`-mtriple=riscv64 -verify-machineinstrs`
machine-cse.c2806996d4.ll (mutant of machine-cse.ll)	commute_fnmsub_f32	`-mtriple=riscv64 -mattr=+f,+d,+zfh -target-abi=lp64d`
machine-cse.eb9f017de0.ll (mutant of machine-cse.ll)	commute_fnmsub_f32	`-mtriple=riscv32 -mattr=+f,+d,+zfh -target-abi=ilp32d`
machine-outliner-and-machine-copy-propagation.ea9e12ddbd.ll (mutant of machine-outliner-and-machine-copy-propagation.ll)	main	`-mtriple=riscv64 -riscv-enable-copy-propagation -enable-machine-outliner -verify-machineinstrs`
memcpy-inline.75076405ce.ll (mutant of memcpy-inline.ll)	aligned_memcpy2	`-mtriple=riscv32 -mattr=+unaligned-scalar-mem`
memcpy-inline.755cbd348f.ll (mutant of memcpy-inline.ll)	aligned_memcpy2	`-mtriple=riscv64`
memcpy-inline.84ec10ee81.ll (mutant of memcpy-inline.ll)	aligned_memcpy2	`-mtriple=riscv64 -mattr=+unaligned-scalar-mem`
memcpy-inline.9847f76909.ll (mutant of memcpy-inline.ll)	aligned_memcpy2	`-mtriple=riscv32`
reduction-formation.4307b533eb.ll (mutant of reduction-formation.ll)	reduce_or_4xi32	`-mtriple=riscv64 -verify-machineinstrs`
reduction-formation.fe78a98ef1.ll (mutant of reduction-formation.ll)	reduce_or_4xi32	`-mtriple=riscv32 -verify-machineinstrs`
typepromotion-overflow.3f82624702.ll (mutant of typepromotion-overflow.ll)	safe_sub_underflow	`-mtriple=riscv64 -mattr=+m`

Generated 2026-10-15 08:05 UTC.