[PATCH] i386: Fix infinite loop under -mrelax-cmpxchg-loop [PR 103069]

[Hongyu Wang via Gcc-patches]

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(+)

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