Re: reload bug

[Jeffrey A Law <law at cygnus dot com>]

[ This discussion originally started within one of Cygnus's newsgroups
  because the change triggered a failure in our nightly testing framework.

  I'm moving the discussion to the gcc-patches list. ]

  In message <Pine.LNX.4.10.9912151521230.10870-100000@balti.cygnus.co.uk>you w
rite:
  > > This change is causing the regressions in plumhall that I posted to
  > > gcc-local on Nov 10:
  > 
  > It's also causing the problems with openssl that were reported on the
  > external list.
  > 
  > > Thu Nov  4 15:52:35 1999  Andrew Haley  <aph@cygnus.com>
  > > 
  > >         * reload1.c (reload_reg_free_for_value_p): Don't use a register
  > >         that is in reload_reg_used.
  > 
  > Below is a patch to fix one half of the problem.  This makes Andrew's
  > change do what was intended.  However, the second half of the problem
  > (inheritance not being disabled properly) is still there, and I don't
  > know yet how to fix it properly.
Just to recap -- Bernd fixed the inheritance problem last week; this is a
cleanup/improvement of Andrew's patch.

The patch is fine.  Please install it.

Thanks for your patience.

  > 	* reload1.c (reload_reg_unavailable): New static variable.
  > 	(reload_reg_free_p): Test it.
  > 	(reload_reg_free_for_value_p): Test it instead of reload_reg_uysed.
  > 	(choose_reload_regs_init): Compute it.
  > 
  > Index: reload1.c
  > ===================================================================
  > RCS file: /cvs/gcc/egcs/gcc/reload1.c,v
  > retrieving revision 1.186
  > diff -c -p -r1.186 reload1.c
  > *** reload1.c	1999/12/14 12:40:02	1.186
  > --- reload1.c	1999/12/15 15:17:30
  > *************** forget_old_reloads_1 (x, ignored, data)
  > *** 3975,3980 ****
  > --- 3975,3982 ----
  >   /* The following HARD_REG_SETs indicate when each hard register is
  >      used for a reload of various parts of the current insn.  */
  >   
  > + /* If reg is unavailable for all reloads.  */
  > + static HARD_REG_SET reload_reg_unavailable;
  >   /* If reg is in use as a reload reg for a RELOAD_OTHER reload.  */
  >   static HARD_REG_SET reload_reg_used;
  >   /* If reg is in use for a RELOAD_FOR_INPUT_ADDRESS reload for operand I. 
  >  */
  > *************** reload_reg_free_p (regno, opnum, type)
  > *** 4198,4204 ****
  >     int i;
  >   
  >     /* In use for a RELOAD_OTHER means it's not available for anything.  */
  > !   if (TEST_HARD_REG_BIT (reload_reg_used, regno))
  >       return 0;
  >   
  >     switch (type)
  > --- 4200,4207 ----
  >     int i;
  >   
  >     /* In use for a RELOAD_OTHER means it's not available for anything.  */
  > !   if (TEST_HARD_REG_BIT (reload_reg_used, regno)
  > !       || TEST_HARD_REG_BIT (reload_reg_unavailable, regno))
  >       return 0;
  >   
  >     switch (type)
  > *************** reload_reg_free_for_value_p (regno, opnu
  > *** 4602,4612 ****
  >     int i;
  >     int copy = 0;
  >   
  > !   /* ??? reload_reg_used is abused to hold the registers that are not
  > !      available as spill registers, including hard registers that are
  > !      earlyclobbered in asms.  As a temporary measure, reject anything
  > !      in reload_reg_used.  */
  > !   if (TEST_HARD_REG_BIT (reload_reg_used, regno))
  >       return 0;
  >   
  >     if (out == const0_rtx)
  > --- 4605,4611 ----
  >     int i;
  >     int copy = 0;
  >   
  > !   if (TEST_HARD_REG_BIT (reload_reg_unavailable, regno))
  >       return 0;
  >   
  >     if (out == const0_rtx)
  > *************** choose_reload_regs_init (chain, save_rel
  > *** 5050,5056 ****
  >         CLEAR_HARD_REG_SET (reload_reg_used_in_outaddr_addr[i]);
  >       }
  >   
  > !   IOR_COMPL_HARD_REG_SET (reload_reg_used, chain->used_spill_regs);
  >   
  >     CLEAR_HARD_REG_SET (reload_reg_used_for_inherit);
  >   
  > --- 5049,5055 ----
  >         CLEAR_HARD_REG_SET (reload_reg_used_in_outaddr_addr[i]);
  >       }
  >   
  > !   COMPL_HARD_REG_SET (reload_reg_unavailable, chain->used_spill_regs);
  >   
  >     CLEAR_HARD_REG_SET (reload_reg_used_for_inherit);
  >   
  > 
  >