[PATCH] Reload fixes for EXTRA_MEMORY_CONSTRAINT problems

["Ulrich Weigand" <Ulrich dot Weigand at de dot ibm dot com>]

Hello,

while experimenting with exploiting the new EXTRA_MEMORY_CONSTRAINT
and EXTRA_ADDRESS_CONSTRAINT features better, I've found two problems:

- In constrain_operands, if an alternative matches exactly, it should
  be preferred over an EXTRA_MEMORY_CONSTRAINT/EXTRA_ADDRESS_CONSTRAINT
  alternative that doesn't match exactly but can be reloaded.

- In find_reloads, if an EXTRA_ADDRESS_CONSTRAINT operand is to be
  reloaded, the reload should use Pmode instead of the operand mode
  specified in the insn (which means something else for address operands).

While I don't have test cases that fail due to these problems with
the current code, I think they should still be fixed.  In some cases,
I do get slightly better code due to the constrain_operands fix even
now.

Bootstrapped/regtested on s390-ibm-linux and s390x-ibm-linux (the
only platforms currently using EXTRA_MEMORY_CONSTRAINT).

OK to apply?


ChangeLog:

      * recog.c (constrain_operands): Prefer exact match over reloadable
      EXTRA_MEMORY_CONSTRAINT or EXTRA_ADDRESS_CONSTRAINT.

      * reload.c (find_reloads): Always reload EXTRA_ADDRESS_CONSTRAINT
      operands in Pmode.

Index: gcc/recog.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/recog.c,v
retrieving revision 1.167
diff -c -p -r1.167 recog.c
*** gcc/recog.c   11 Nov 2002 05:38:22 -0000    1.167
--- gcc/recog.c   19 Nov 2002 15:09:32 -0000
*************** constrain_operands (strict)
*** 2628,2650 ****

              if (EXTRA_MEMORY_CONSTRAINT (c))
                {
!                 /* Every memory operand can be reloaded to fit,
!                  so copy the condition from the 'm' case.  */
!                 if (GET_CODE (op) == MEM
!                     /* Before reload, accept what reload can turn into mem.  */
!                     || (strict < 0 && CONSTANT_P (op))
!                     /* During reload, accept a pseudo  */
!                     || (reload_in_progress && GET_CODE (op) == REG
!                       && REGNO (op) >= FIRST_PSEUDO_REGISTER))
                  win = 1;
                }
              if (EXTRA_ADDRESS_CONSTRAINT (c))
                {
!                 /* Every address operand can be reloaded to fit,
!                  so copy the condition from the 'p' case.  */
!                 if (strict <= 0
!                     || (strict_memory_address_p (recog_data.operand_mode[opno],
!                                          op)))
                    win = 1;
                }
  #endif
--- 2628,2650 ----

              if (EXTRA_MEMORY_CONSTRAINT (c))
                {
!                 /* Every memory operand can be reloaded to fit.  */
!                 if (strict < 0 && GET_CODE (op) == MEM)
!                 win = 1;
!
!                 /* Before reload, accept what reload can turn into mem.  */
!                 if (strict < 0 && CONSTANT_P (op))
!                 win = 1;
!
!                 /* During reload, accept a pseudo  */
!                 if (reload_in_progress && GET_CODE (op) == REG
!                   && REGNO (op) >= FIRST_PSEUDO_REGISTER)
                  win = 1;
                }
              if (EXTRA_ADDRESS_CONSTRAINT (c))
                {
!                 /* Every address operand can be reloaded to fit.  */
!                 if (strict < 0)
                    win = 1;
                }
  #endif
Index: gcc/reload.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/reload.c,v
retrieving revision 1.197
diff -c -p -r1.197 reload.c
*** gcc/reload.c  4 Nov 2002 16:57:02 -0000     1.197
--- gcc/reload.c  19 Nov 2002 15:09:36 -0000
*************** find_reloads (insn, replace, ind_levels,
*** 3283,3288 ****
--- 3283,3292 ----
                     the address into a base register.  */
                  this_alternative[i] = (int) MODE_BASE_REG_CLASS (VOIDmode);
                  badop = 0;
+
+                 /* Address constraints are reloaded in Pmode, no matter
+                    what mode is given in the machine description.  */
+                 operand_mode[i] = Pmode;
                  break;
                  }


Mit freundlichen Gruessen / Best Regards

Ulrich Weigand

--
  Dr. Ulrich Weigand
  Linux for S/390 Design & Development
  IBM Deutschland Entwicklung GmbH, Schoenaicher Str. 220, 71032 Boeblingen
  Phone: +49-7031/16-3727   ---   Email: Ulrich.Weigand@de.ibm.com