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

[rguenth at gcc dot gnu.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++;