Re: regrename doesn't take HARD_REGNO_CALL_PART_CLOBBERED into account

[Alexandre Oliva <aoliva at redhat dot com>]

On Mar 11, 2001, Alexandre Oliva <aoliva@redhat.com> wrote:

> It is possible that regrename chooses a register that may be partially
> clobbered in function calls to replace one that is fully saved in the
> mode(s) in which the register is used.  It shouldn't do it.  This
> patch fixes it.

And this patch improves it, by not requiring a non-part-clobbered
register if the originally chosen register is part-clobbered.  I've
also caught a few cases in global alloc that didn't take the macro
into account, which fixed a few additional bugs in that port.  Tested
on a new port, yet to be contributed.  Ok to install?

Index: gcc/ChangeLog

	* regrename.c (regrename_optimize): Don't use a register that may
	be part-clobbered in the used modes.
	* global.c (find_reg): Ditto.

Index: gcc/regrename.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/regrename.c,v
retrieving revision 1.20
diff -u -p -r1.20 regrename.c
--- gcc/regrename.c 2001/01/04 14:17:38 1.20
+++ gcc/regrename.c 2001/03/18 05:51:18
@@ -1,5 +1,5 @@
 /* Register renaming for the GNU compiler.
-   Copyright (C) 2000 Free Software Foundation, Inc.
+   Copyright (C) 2000, 2001 Free Software Foundation, Inc.
 
    This file is part of GNU CC.
 
@@ -303,7 +303,12 @@ regrename_optimize ()
 	      /* See whether it accepts all modes that occur in
 		 definition and uses.  */
 	      for (tmp = this; tmp; tmp = tmp->next_use)
-		if (! HARD_REGNO_MODE_OK (new_reg, GET_MODE (*tmp->loc)))
+		if (! HARD_REGNO_MODE_OK (new_reg, GET_MODE (*tmp->loc))
+		    || (last->need_caller_save_reg
+			&& ! (HARD_REGNO_CALL_PART_CLOBBERED
+			      (reg, GET_MODE (*tmp->loc)))
+			&& (HARD_REGNO_CALL_PART_CLOBBERED
+			    (new_reg, GET_MODE (*tmp->loc)))))
 		  break;
 	      if (! tmp)
 		{
Index: gcc/global.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/global.c,v
retrieving revision 1.65
diff -u -p -r1.65 global.c
--- gcc/global.c 2000/12/05 19:12:19 1.65
+++ gcc/global.c 2001/03/18 05:51:18
@@ -1,6 +1,6 @@
 /* Allocate registers for pseudo-registers that span basic blocks.
    Copyright (C) 1987, 1988, 1991, 1994, 1996, 1997, 1998,
-   1999, 2000 Free Software Foundation, Inc.
+   1999, 2000, 2001 Free Software Foundation, Inc.
 
 This file is part of GNU CC.
 
@@ -1076,6 +1076,10 @@ find_reg (num, losers, alt_regs_p, accep
       for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
 	if (TEST_HARD_REG_BIT (allocno[num].hard_reg_copy_preferences, i)
 	    && HARD_REGNO_MODE_OK (i, mode)
+	    && (allocno[num].calls_crossed == 0
+		|| accept_call_clobbered
+		|| HARD_REGNO_CALL_PART_CLOBBERED (best_reg, mode)
+		|| ! HARD_REGNO_CALL_PART_CLOBBERED (i, mode))
 	    && (REGNO_REG_CLASS (i) == REGNO_REG_CLASS (best_reg)
 		|| reg_class_subset_p (REGNO_REG_CLASS (i),
 				       REGNO_REG_CLASS (best_reg))
@@ -1112,6 +1116,10 @@ find_reg (num, losers, alt_regs_p, accep
       for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
 	if (TEST_HARD_REG_BIT (allocno[num].hard_reg_preferences, i)
 	    && HARD_REGNO_MODE_OK (i, mode)
+	    && (allocno[num].calls_crossed == 0
+		|| accept_call_clobbered
+		|| HARD_REGNO_CALL_PART_CLOBBERED (best_reg, mode)
+		|| ! HARD_REGNO_CALL_PART_CLOBBERED (i, mode))
 	    && (REGNO_REG_CLASS (i) == REGNO_REG_CLASS (best_reg)
 		|| reg_class_subset_p (REGNO_REG_CLASS (i),
 				       REGNO_REG_CLASS (best_reg))
@@ -1192,6 +1200,9 @@ find_reg (num, losers, alt_regs_p, accep
 	      /* Don't use a reg no good for this pseudo.  */
 	      && ! TEST_HARD_REG_BIT (used2, regno)
 	      && HARD_REGNO_MODE_OK (regno, mode)
+	      && (allocno[num].calls_crossed == 0
+		  || accept_call_clobbered
+		  || ! HARD_REGNO_CALL_PART_CLOBBERED (regno, mode))
 #ifdef CLASS_CANNOT_CHANGE_MODE
 	      && ! (REG_CHANGES_MODE (allocno[num].reg)
 		    && (TEST_HARD_REG_BIT

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                  aoliva@{cygnus.com, redhat.com}
CS PhD student at IC-Unicamp        oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist    *Please* write to mailing lists, not to me