From 522f25e90c781d284f8347a04940db8b41c42fd5 Mon Sep 17 00:00:00 2001 From: Hongyu Wang Date: Wed, 13 Apr 2022 14:51:36 +0800 Subject: [PATCH] i386: Fix infinite loop under -mrelax-cmpxchg-loop [PR 103069] For -mrelax-cmpxchg-loop which relaxes atomic_fetch_ loops, there is a missing set to %eax when compare fails, which would result in infinite loop in some benchmark. Add set to %eax to avoid it. gcc/ChangeLog: PR target/103069 * config/i386/i386-expand.cc (ix86_expand_cmpxchg_loop): Add missing set to target_val at pause label. --- gcc/config/i386/i386-expand.cc | 1 + 1 file changed, 1 insertion(+) diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc index 677059b0061f..68978ef8dc26 100644 --- a/gcc/config/i386/i386-expand.cc +++ b/gcc/config/i386/i386-expand.cc @@ -23405,6 +23405,7 @@ ix86_expand_cmpxchg_loop (rtx *ptarget_bool, rtx target_val, /* If mem is not expected, pause and loop back. */ emit_label (cmp_label); + emit_move_insn (target_val, new_mem); emit_insn (gen_pause ()); emit_jump_insn (gen_jump (loop_label)); emit_barrier ();