From 021ccf9dee0c14455a205f2555326e027e9047d8 Mon Sep 17 00:00:00 2001 From: Richard Sandiford Date: Wed, 16 Apr 2025 13:20:25 +0100 Subject: [PATCH] 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. (cherry picked from commit 01044471ea39f9be4803c583ef2a946abc657f99) --- gcc/explow.cc | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/gcc/explow.cc b/gcc/explow.cc index f6843398c4b..bd93c878064 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 -- 2.50.1