fallback: legalize: G_STRICT_FSUB s16

Run:explore-04ca53e65f-20261014-114124
Kind:fallback
Category:legalize: G_STRICT_FSUB s16
Occurrences:16 in 8 configs, 1 test files
Snippet from:half-arith-strict.ll @fsub_h via llvm-extract
Config:-mtriple=riscv32 -mattr=+zfh -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32f
Local check:reproduces at 04ca53e65f
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

; Function Attrs: nounwind strictfp
define half @fsub_h(half %a, half %b) #0 {
  %1 = call half @llvm.experimental.constrained.fsub.f16(half %a, half %b, metadata !"round.dynamic", metadata !"fpexcept.strict") #2
  ret half %1
}

; Function Attrs: nocallback nofree nosync nounwind strictfp willreturn memory(inaccessiblemem: readwrite)
declare half @llvm.experimental.constrained.fsub.f16(half, half, metadata, metadata) #1

attributes #0 = { nounwind strictfp }
attributes #1 = { nocallback nofree nosync nounwind strictfp willreturn memory(inaccessiblemem: readwrite) }
attributes #2 = { strictfp }

Reproduce:

llc -mtriple=riscv32 -mattr=+zfh -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32f -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv32 -mattr=+zfh -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32f -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %2:_(s16) = G_STRICT_FSUB %0:_, %1:_ (in function: fsub_h)
warning: Instruction selection used fallback path for fsub_h

Occurrences (16):

InputFunctionConfig
half-arith-strict.llfsub_h-mtriple=riscv32 -mattr=+zfh -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32f
half-arith-strict.llfsub_h-mtriple=riscv32 -mattr=+zfhmin -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32f
half-arith-strict.llfsub_h-mtriple=riscv32 -mattr=+zhinx -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32
half-arith-strict.llfsub_h-mtriple=riscv32 -mattr=+zhinxmin -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32
half-arith-strict.llfsub_h-mtriple=riscv64 -mattr=+zfh -verify-machineinstrs -disable-strictnode-mutation -target-abi lp64f
half-arith-strict.llfsub_h-mtriple=riscv64 -mattr=+zfhmin -verify-machineinstrs -disable-strictnode-mutation -target-abi lp64f
half-arith-strict.llfsub_h-mtriple=riscv64 -mattr=+zhinx -verify-machineinstrs -disable-strictnode-mutation -target-abi lp64
half-arith-strict.llfsub_h-mtriple=riscv64 -mattr=+zhinxmin -verify-machineinstrs -disable-strictnode-mutation -target-abi lp64
half-arith-strict.160f7e04d6.ll (mutant of half-arith-strict.ll)fsub_h-mtriple=riscv32 -mattr=+zfhmin -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32f
half-arith-strict.270c53a675.ll (mutant of half-arith-strict.ll)fsub_h-mtriple=riscv64 -mattr=+zhinxmin -verify-machineinstrs -disable-strictnode-mutation -target-abi lp64
half-arith-strict.2f0b3b7ea5.ll (mutant of half-arith-strict.ll)fsub_h-mtriple=riscv32 -mattr=+zhinxmin -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32
half-arith-strict.4205f05c8b.ll (mutant of half-arith-strict.ll)fsub_h-mtriple=riscv64 -mattr=+zfhmin -verify-machineinstrs -disable-strictnode-mutation -target-abi lp64f
half-arith-strict.42e6191dff.ll (mutant of half-arith-strict.ll)fsub_h-mtriple=riscv64 -mattr=+zfh -verify-machineinstrs -disable-strictnode-mutation -target-abi lp64f
half-arith-strict.602c0db108.ll (mutant of half-arith-strict.ll)fsub_h-mtriple=riscv64 -mattr=+zhinx -verify-machineinstrs -disable-strictnode-mutation -target-abi lp64
half-arith-strict.79d3ec8520.ll (mutant of half-arith-strict.ll)fsub_h-mtriple=riscv32 -mattr=+zhinx -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32
half-arith-strict.b2384174a4.ll (mutant of half-arith-strict.ll)fsub_h-mtriple=riscv32 -mattr=+zfh -verify-machineinstrs -disable-strictnode-mutation -target-abi ilp32f

Generated 2026-10-15 08:05 UTC.