| Message ID | 20220413070654.60138-1-hongyu.wang@intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | i386: Fix infinite loop under -mrelax-cmpxchg-loop [PR 103069] | expand |
On Wed, Apr 13, 2022 at 9:07 AM Hongyu Wang <hongyu.wang@intel.com> wrote: > > Hi, > > For -mrelax-cmpxchg-loop which relaxes atomic_fetch_<logic> 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. > > Bootstraped/regtested on x86_64-pc-linux-gnu{-m32,} > > Ok for master? > > gcc/ChangeLog: > > PR target/103069 > * config/i386/i386-expand.cc (ix86_expand_cmpxchg_loop): > Add missing set to target_val at pause label. LGTM. Uros. > --- > 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 794315ee2f7..2144d3f968d 100644 > --- a/gcc/config/i386/i386-expand.cc > +++ b/gcc/config/i386/i386-expand.cc > @@ -23388,6 +23388,7 @@ void 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 (); > -- > 2.18.1 >
diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc index 794315ee2f7..2144d3f968d 100644 --- a/gcc/config/i386/i386-expand.cc +++ b/gcc/config/i386/i386-expand.cc @@ -23388,6 +23388,7 @@ void 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 ();
Hi, For -mrelax-cmpxchg-loop which relaxes atomic_fetch_<logic> 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. Bootstraped/regtested on x86_64-pc-linux-gnu{-m32,} Ok for master? 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(+)