[Bug target/55752] __builtin_ia32_ldmxcsr / __builtin_ia32_stmxcsr are not scheduling barriers

["rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55752

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-12-20
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> 2012-12-20 13:32:02 UTC ---
TER already avoids moving things across calls but:

      /* Increment counter if this is a non BUILT_IN call. We allow
         replacement over BUILT_IN calls since many will expand to inline
         insns instead of a true call.  */
      if (is_gimple_call (stmt)
          && !((fndecl = gimple_call_fndecl (stmt))
               && DECL_BUILT_IN (fndecl)))
        cur_call_cnt++;

so it special-cases all builtins (I can see __builtin_sqrt as a good
example where this is a good idea).  OTOH __builtin_ia32_stmxcsr/
__builtin_ia32_ldmxcsr are neither const nor pure, so maybe
restricting this further, like

      /* Increment counter if this is not a BUILT_IN call without
         side-effects.  We allow replacement over BUILT_IN calls 
         since many will expand to inline insns instead of a true call.  */
      if (is_gimple_call (stmt)
          && (!((fndecl = gimple_call_fndecl (stmt))
                && DECL_BUILT_IN (fndecl))
              || gimple_has_side_effects (stmt)))
        cur_call_cnt++;