fallback: translate: call llvm.fabs.nxv4f32

Run:	explore-04ca53e65f-20261014-114124
Kind:	fallback
Category:	translate: call llvm.fabs.nxv4f32
Occurrences:	4 in 2 configs, 2 test files
Snippet from:	known-fpclass.ll @test_full_fabs_nan_vs_nan via llvm-extract
Config:	`-mtriple=riscv64 -mattr=+v,+f,+d -target-abi=lp64d`
Local check:	reproduces at 04ca53e65f
Compiler Explorer:	not uploaded (over --godbolt-limit or disabled)

Snippet:

define <vscale x 4 x i1> @test_full_fabs_nan_vs_nan(<vscale x 4 x float> nofpclass(nan) %a) {
  %abs = call <vscale x 4 x float> @llvm.fabs.nxv4f32(<vscale x 4 x float> %a)
  %class = call <vscale x 4 x i1> @llvm.is.fpclass.nxv4f32(<vscale x 4 x float> %abs, /* (nan) */ i32 3)
  ret <vscale x 4 x i1> %class
}

; Function Attrs: nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none)
declare <vscale x 4 x float> @llvm.fabs.nxv4f32(<vscale x 4 x float>) #0

; Function Attrs: nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none)
declare <vscale x 4 x i1> @llvm.is.fpclass.nxv4f32(<vscale x 4 x float>, i32 immarg) #0

attributes #0 = { nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none) }

Reproduce:

llc -mtriple=riscv64 -mattr=+v,+f,+d -target-abi=lp64d -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv64 -mattr=+v,+f,+d -target-abi=lp64d -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to translate instruction: call llvm.fabs.nxv4f32: '  %abs = call <vscale x 4 x float> @llvm.fabs.nxv4f32(<vscale x 4 x float> %a)' (in function: test_full_fabs_nan_vs_nan)
warning: Instruction selection used fallback path for test_full_fabs_nan_vs_nan

Occurrences (4):

Input	Function	Config
combine-is_fpclass.ll	extract_scalable_fabs_isneg	`-mtriple=riscv64 -mattr=+v,+f,+d`
combine-is_fpclass.ll	insert_subvec_scalable_both_isneg_false	`-mtriple=riscv64 -mattr=+v,+f,+d`
known-fpclass.ll	test_full_fabs_nan_vs_nan	`-mtriple=riscv64 -mattr=+v,+f,+d -target-abi=lp64d`
combine-is_fpclass.4aec096e3d.ll (mutant of combine-is_fpclass.ll)	extract_scalable_fabs_isneg	`-mtriple=riscv64 -mattr=+v,+f,+d`

Generated 2026-10-15 08:05 UTC.