[Bug target/91719] gcc compiles seq_cst store on x86-64 differently from clang/icc

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91719

Uroš Bizjak <ubizjak at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2019-09-10
           Assignee|unassigned at gcc dot gnu.org      |ubizjak at gmail dot com
   Target Milestone|---                         |10.0
     Ever confirmed|0                           |1

--- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> ---
Proposed patch:

--cut here--
diff --git a/gcc/config/i386/sync.md b/gcc/config/i386/sync.md
index ba146e3c8f81..b23dbf93bde7 100644
--- a/gcc/config/i386/sync.md
+++ b/gcc/config/i386/sync.md
@@ -306,8 +306,8 @@
     {
       operands[1] = force_reg (<MODE>mode, operands[1]);

-      /* For seq-cst stores, when we lack MFENCE, use XCHG.  */
-      if (is_mm_seq_cst (model) && !(TARGET_64BIT || TARGET_SSE2))
+      /* For seq-cst stores use XCHG.  */
+      if (is_mm_seq_cst (model))
        {
          emit_insn (gen_atomic_exchange<mode> (gen_reg_rtx (<MODE>mode),
                                                operands[0], operands[1],
--cut here--