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

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.

gcc/ChangeLog:

	PR target/103069
	* config/i386/i386-expand.cc (ix86_expand_cmpxchg_loop):
	  Add missing set to target_val at pause label.
This commit is contained in:
Hongyu Wang 2022-04-13 14:51:36 +08:00
parent 41f8f8b8a4
commit 522f25e90c

View File

@ -23405,6 +23405,7 @@ ix86_expand_cmpxchg_loop (rtx *ptarget_bool, rtx target_val,
/* If mem is not expected, pause and loop back. */ /* If mem is not expected, pause and loop back. */
emit_label (cmp_label); emit_label (cmp_label);
emit_move_insn (target_val, new_mem);
emit_insn (gen_pause ()); emit_insn (gen_pause ());
emit_jump_insn (gen_jump (loop_label)); emit_jump_insn (gen_jump (loop_label));
emit_barrier (); emit_barrier ();