loop.c (check_final_value): A GIV is not replaceable if used before set.

	2000-09-29  Franz Sirl  <Franz.Sirl-kernel@lauterbach.com>
	* loop.c (check_final_value): A GIV is not replaceable if used
	before set.

From-SVN: r36668

2 files changed, 20 insertions, 21 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2a32857..86baecc 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2000-09-29  Franz Sirl  <Franz.Sirl-kernel@lauterbach.com>
+
+	* loop.c (check_final_value): A GIV is not replaceable if used
+	before set.
+
 Fri Sep 29 10:04:12 2000  Jeffrey A Law  (law@cygnus.com)
 
 	* version.c: Bump to gcc-2.97.
@@ -62,6 +67,7 @@ Fri Sep 29 13:20:42 MET DST 2000  Jan Hubicka  <jh@suse.cz>
 	* configure: Rebuilt.
 
 2000-09-28  Franz Sirl  <Franz.Sirl-kernel@lauterbach.com>
+
 	* doloop.c (doloop_modify): Prevent delete_insn() from
 	deleting too much.  Prefer loop->top over loop->start as
 	target for the new JUMP insn.
@@ -2743,16 +2749,6 @@ Sat Sep  2 13:58:23 2000  Marek Michalkiewicz <marekm@linux.org.pl>
 	* config/avr/avr.md ("*negsi2"): substitute %@ to __zero_reg__
 	* config/avr/libgcc.S: Lost part of the previous patch.
 
-2000-08-31  Franz Sirl  <Franz.Sirl-kernel@lauterbach.com>
-
-	* rs6000/rs6000.h (NO_DOLLAR_IN_LABEL, DOLLARS_IN_IDENTIFIERS,
-	ENCODE_SECTION_INFO, ASM_OUTPUT_SPECIAL_POOL_ENTRY_P): Move from
-	here...
-	* rs6000/aix.h: ...to here.
-	* rs6000/linux.h (ASM_APP_ON, ASM_APP_OFF): Define to Linux-style.
-	* rs6000/rs6000.c (rs6000_select_section): Handle CONSTRUCTOR.
-	(rs6000_unique_section): Likewise.
-
 2000-08-31  J. David Anglin  <dave@hiauly1.hia.nrc.ca>
 
 	* gthr-dce.h (__gthread_objc_mutex_allocate): Create a pthread_mutex_t
diff --git a/gcc/loop.c b/gcc/loop.c
index b53b148..f685b39 100644
--- a/gcc/loop.c
+++ b/gcc/loop.c
@@ -5094,6 +5094,7 @@ check_final_value (loop, v)
         or all uses follow that insn in the same basic block),
      - its final value can be calculated (this condition is different
        than the one above in record_giv)
+     - it's not used before the it's set
      - no assignments to the biv occur during the giv's lifetime.  */
 
 #if 0
@@ -5105,7 +5106,7 @@ check_final_value (loop, v)
   if ((final_value = final_giv_value (loop, v))
       && (v->always_computable || last_use_this_basic_block (v->dest_reg, v->insn)))
     {
-      int biv_increment_seen = 0;
+      int biv_increment_seen = 0, before_giv_insn = 0;
       rtx p = v->insn;
       rtx last_giv_use;
 
@@ -5135,7 +5136,10 @@ check_final_value (loop, v)
 	{
 	  p = NEXT_INSN (p);
 	  if (p == loop->end)
-	    p = NEXT_INSN (loop->start);
+	    {
+	      before_giv_insn = 1;
+	      p = NEXT_INSN (loop->start);
+	    }
 	  if (p == v->insn)
 	    break;
 
@@ -5153,7 +5157,7 @@ check_final_value (loop, v)
 
 	      if (reg_mentioned_p (v->dest_reg, PATTERN (p)))
 		{
-		  if (biv_increment_seen)
+		  if (biv_increment_seen || before_giv_insn)
 		    {
 		      v->replaceable = 0;
 		      v->not_replaceable = 1;
@@ -5438,14 +5442,13 @@ basic_induction_var (loop, x, mode, dest_reg, p, inc_val, mult_val, location)
 		       <= UNITS_PER_WORD)
 		   && (GET_MODE_CLASS (GET_MODE (SET_DEST (set)))
 		       == MODE_INT)
-		   && SUBREG_REG (SET_DEST (set)) == x))
-	      && basic_induction_var (loop, SET_SRC (set),
-				      (GET_MODE (SET_SRC (set)) == VOIDmode
-				       ? GET_MODE (x)
-				       : GET_MODE (SET_SRC (set))),
-				      dest_reg, insn,
-				      inc_val, mult_val, location))
-	    return 1;
+		   && SUBREG_REG (SET_DEST (set)) == x)))
+	      return basic_induction_var (loop, SET_SRC (set),
+					  (GET_MODE (SET_SRC (set)) == VOIDmode
+					   ? GET_MODE (x)
+					   : GET_MODE (SET_SRC (set))),
+					  dest_reg, insn,
+					  inc_val, mult_val, location);
 	}
       /* Fall through.  */