https://gcc.gnu.org/g:01044471ea39f9be4803c583ef2a946abc657f99
commit r15-1395-g01044471ea39f9be4803c583ef2a946abc657f99 Author: Richard Sandiford <richard.sandif...@arm.com> Date: Tue Jun 18 12:22:30 2024 +0100 Make force_subreg emit nothing on failure While adding more uses of force_subreg, I realised that it should be more careful to emit no instructions on failure. This kind of failure should be very rare, so I don't think it's a case worth optimising for. gcc/ * explow.cc (force_subreg): Emit no instructions on failure. Diff: --- gcc/explow.cc | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/gcc/explow.cc b/gcc/explow.cc index f6843398c4b0..bd93c8780649 100644 --- a/gcc/explow.cc +++ b/gcc/explow.cc @@ -756,8 +756,12 @@ force_subreg (machine_mode outermode, rtx op, if (x) return x; + auto *start = get_last_insn (); op = copy_to_mode_reg (innermode, op); - return simplify_gen_subreg (outermode, op, innermode, byte); + rtx res = simplify_gen_subreg (outermode, op, innermode, byte); + if (!res) + delete_insns_since (start); + return res; } /* If X is a memory ref, copy its contents to a new temp reg and return