expr.h (canonicalize_condition, [...]): Add an int argument.

	* expr.h (canonicalize_condition, get_condition): Add an int argument.
	* gcse.c (fis_get_condition): Reimplement using get_condition, leaving
	it to check whether the condition is still valid at the jump insn.
	* ifcvt.c (noce_get_condition): Likewise.
	(noce_get_alt_condition): Update call to canonicalize_condition.
	* loop-iv.c (simplify_using_initial_values): Update call to
	get_condition.  Remove FIXME.
	(check_simple_exit): Update call to get_condition.
	* loop-unswitch.c (may_unswitch_on): Likewise.
	* loop.c (check_dbra_loop): Likewise.
	(canonicalize_condition, get_condition): Add an argument to say whether
	the condition must still be valid at INSN.
	(get_condition_for_loop): Update call to get_condition.  Require that
	the condition be valid at INSN.
	* predict.c (estimate_probability): Update call to get_condition.
	Remove unused earliest parameter.
	(expected_value_to_br_prob): Update call to canonicalize_condition.

From-SVN: r85218

gcc/ChangeLog

+2004-07-27  Richard Sandiford  <rsandifo@redhat.com>
+
+	* expr.h (canonicalize_condition, get_condition): Add an int argument.
+	* gcse.c (fis_get_condition): Reimplement using get_condition, leaving
+	it to check whether the condition is still valid at the jump insn.
+	* ifcvt.c (noce_get_condition): Likewise.
+	(noce_get_alt_condition): Update call to canonicalize_condition.
+	* loop-iv.c (simplify_using_initial_values): Update call to
+	get_condition.  Remove FIXME.
+	(check_simple_exit): Update call to get_condition.
+	* loop-unswitch.c (may_unswitch_on): Likewise.
+	* loop.c (check_dbra_loop): Likewise.
+	(canonicalize_condition, get_condition): Add an argument to say whether
+	the condition must still be valid at INSN.
+	(get_condition_for_loop): Update call to get_condition.  Require that
+	the condition be valid at INSN.
+	* predict.c (estimate_probability): Update call to get_condition.
+	Remove unused earliest parameter.
+	(expected_value_to_br_prob): Update call to canonicalize_condition.
+
 2004-07-26  Eric Christopher  <echristo@redhat.com>
 
 	* tree-dfa.c (add_referenced_var): Register initializers of global

gcc/expr.h

@@ -338,11 +338,11 @@ extern rtx emit_store_flag_force (rtx, enum rtx_code, rtx, rtx,
 
 /* Given an insn and condition, return a canonical description of
    the test being made.  */
-extern rtx canonicalize_condition (rtx, rtx, int, rtx *, rtx, int);
+extern rtx canonicalize_condition (rtx, rtx, int, rtx *, rtx, int, int);
 
 /* Given a JUMP_INSN, return a canonical description of the test
    being made.  */
-extern rtx get_condition (rtx, rtx *, int);
+extern rtx get_condition (rtx, rtx *, int, int);
 
 /* Generate a conditional trap instruction.  */
 extern rtx gen_cond_trap (enum rtx_code, rtx, rtx, rtx);

gcc/gcse.c

@@ -3687,52 +3687,7 @@ cprop (int alter_jumps)
 rtx
 fis_get_condition (rtx jump)
 {
-  rtx cond, set, tmp, insn, earliest;
-  bool reverse;
-
-  if (! any_condjump_p (jump))
-    return NULL_RTX;
-
-  set = pc_set (jump);
-  cond = XEXP (SET_SRC (set), 0);
-
-  /* If this branches to JUMP_LABEL when the condition is false,
-     reverse the condition.  */
-  reverse = (GET_CODE (XEXP (SET_SRC (set), 2)) == LABEL_REF
-	     && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump));
-
-  /* Use canonicalize_condition to do the dirty work of manipulating
-     MODE_CC values and COMPARE rtx codes.  */
-  tmp = canonicalize_condition (jump, cond, reverse, &earliest, NULL_RTX,
-				false);
-  if (!tmp)
-    return NULL_RTX;
-
-  /* Verify that the given condition is valid at JUMP by virtue of not
-     having been modified since EARLIEST.  */
-  for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
-    if (INSN_P (insn) && modified_in_p (tmp, insn))
-      break;
-  if (insn == jump)
-    return tmp;
-
-  /* The condition was modified.  See if we can get a partial result
-     that doesn't follow all the reversals.  Perhaps combine can fold
-     them together later.  */
-  tmp = XEXP (tmp, 0);
-  if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
-    return NULL_RTX;
-  tmp = canonicalize_condition (jump, cond, reverse, &earliest, tmp,
-				false);
-  if (!tmp)
-    return NULL_RTX;
-
-  /* For sanity's sake, re-validate the new result.  */
-  for (insn = earliest; insn != jump; insn = NEXT_INSN (insn))
-    if (INSN_P (insn) && modified_in_p (tmp, insn))
-      return NULL_RTX;
-
-  return tmp;
+  return get_condition (jump, NULL, false, true);
 }
 
 /* Check the comparison COND to see if we can safely form an implicit set from

gcc/ifcvt.c

@@ -1489,7 +1489,7 @@ noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
     }
 
   cond = canonicalize_condition (if_info->jump, cond, reverse,
-				 earliest, target, false);
+				 earliest, target, false, true);
   if (! cond || ! reg_mentioned_p (target, cond))
     return NULL;
 
@@ -1800,7 +1800,7 @@ noce_try_sign_mask (struct noce_if_info *if_info)
 static rtx
 noce_get_condition (rtx jump, rtx *earliest)
 {
-  rtx cond, set, tmp, insn;
+  rtx cond, set, tmp;
   bool reverse;
 
   if (! any_condjump_p (jump))
@@ -1829,38 +1829,8 @@ noce_get_condition (rtx jump, rtx *earliest)
 
   /* Otherwise, fall back on canonicalize_condition to do the dirty
      work of manipulating MODE_CC values and COMPARE rtx codes.  */
-
-  tmp = canonicalize_condition (jump, cond, reverse, earliest, NULL_RTX,
-				false);
-  if (!tmp)
-    return NULL_RTX;
-
-  /* We are going to insert code before JUMP, not before EARLIEST.
-     We must therefore be certain that the given condition is valid
-     at JUMP by virtue of not having been modified since.  */
-  for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
-    if (INSN_P (insn) && modified_in_p (tmp, insn))
-      break;
-  if (insn == jump)
-    return tmp;
-
-  /* The condition was modified.  See if we can get a partial result
-     that doesn't follow all the reversals.  Perhaps combine can fold
-     them together later.  */
-  tmp = XEXP (tmp, 0);
-  if (!REG_P (tmp) || GET_MODE_CLASS (GET_MODE (tmp)) != MODE_INT)
-    return NULL_RTX;
-  tmp = canonicalize_condition (jump, cond, reverse, earliest, tmp,
-				false);
-  if (!tmp)
-    return NULL_RTX;
-
-  /* For sanity's sake, re-validate the new result.  */
-  for (insn = *earliest; insn != jump; insn = NEXT_INSN (insn))
-    if (INSN_P (insn) && modified_in_p (tmp, insn))
-      return NULL_RTX;
-
-  return tmp;
+  return canonicalize_condition (jump, cond, reverse, earliest,
+				 NULL_RTX, false, true);
 }
 
 /* Return true if OP is ok for if-then-else processing.  */

gcc/loop-iv.c

@@ -1737,9 +1737,7 @@ simplify_using_initial_values (struct loop *loop, enum rtx_code op, rtx *expr)
       insn = BB_END (e->src);
       if (any_condjump_p (insn))
 	{
-	  /* FIXME -- slightly wrong -- what if compared register
-	     gets altered between start of the condition and insn?  */
-	  rtx cond = get_condition (BB_END (e->src), NULL, false);
+	  rtx cond = get_condition (BB_END (e->src), NULL, false, true);
       
 	  if (cond && (e->flags & EDGE_FALLTHRU))
 	    cond = reversed_condition (cond);
@@ -2472,7 +2470,7 @@ check_simple_exit (struct loop *loop, edge e, struct niter_desc *desc)
   desc->in_edge = ei;
 
   /* Test whether the condition is suitable.  */
-  if (!(condition = get_condition (BB_END (ei->src), &at, false)))
+  if (!(condition = get_condition (BB_END (ei->src), &at, false, false)))
     return;
 
   if (ei->flags & EDGE_FALLTHRU)

gcc/loop-unswitch.c

@@ -196,7 +196,7 @@ may_unswitch_on (basic_block bb, struct loop *loop, rtx *cinsn)
     return NULL_RTX;
 
   /* Condition must be invariant.  */
-  test = get_condition (BB_END (bb), &at, true);
+  test = get_condition (BB_END (bb), &at, true, false);
   if (!test)
     return NULL_RTX;
 

gcc/loop.c

@@ -8001,7 +8001,7 @@ check_dbra_loop (struct loop *loop, int insn_count)
 
   /* Try to compute whether the compare/branch at the loop end is one or
      two instructions.  */
-  get_condition (jump, &first_compare, false);
+  get_condition (jump, &first_compare, false, true);
   if (first_compare == jump)
     compare_and_branch = 1;
   else if (first_compare == prev_nonnote_insn (jump))
@@ -9195,11 +9195,14 @@ update_reg_last_use (rtx x, rtx insn)
    If WANT_REG is nonzero, we wish the condition to be relative to that
    register, if possible.  Therefore, do not canonicalize the condition
    further.  If ALLOW_CC_MODE is nonzero, allow the condition returned 
-   to be a compare to a CC mode register.  */
+   to be a compare to a CC mode register.
+
+   If VALID_AT_INSN_P, the condition must be valid at both *EARLIEST
+   and at INSN.  */
 
 rtx
 canonicalize_condition (rtx insn, rtx cond, int reverse, rtx *earliest,
-			rtx want_reg, int allow_cc_mode)
+			rtx want_reg, int allow_cc_mode, int valid_at_insn_p)
 {
   enum rtx_code code;
   rtx prev = insn;
@@ -9357,6 +9360,11 @@ canonicalize_condition (rtx insn, rtx cond, int reverse, rtx *earliest,
 
       if (x)
 	{
+	  /* If the caller is expecting the condition to be valid at INSN,
+	     make sure X doesn't change before INSN.  */
+	  if (valid_at_insn_p)
+	    if (modified_in_p (x, prev) || modified_between_p (x, prev, insn))
+	      break;
 	  if (COMPARISON_P (x))
 	    code = GET_CODE (x);
 	  if (reverse_code)
@@ -9443,13 +9451,16 @@ canonicalize_condition (rtx insn, rtx cond, int reverse, rtx *earliest,
    If EARLIEST is nonzero, it is a pointer to a place where the earliest
    insn used in locating the condition was found.  If a replacement test
    of the condition is desired, it should be placed in front of that
-   insn and we will be sure that the inputs are still valid.  
+   insn and we will be sure that the inputs are still valid.  If EARLIEST
+   is null, the returned condition will be valid at INSN.
 
    If ALLOW_CC_MODE is nonzero, allow the condition returned to be a
-   compare CC mode register.  */
+   compare CC mode register.
+
+   VALID_AT_INSN_P is the same as for canonicalize_condition.  */
 
 rtx
-get_condition (rtx jump, rtx *earliest, int allow_cc_mode)
+get_condition (rtx jump, rtx *earliest, int allow_cc_mode, int valid_at_insn_p)
 {
   rtx cond;
   int reverse;
@@ -9470,7 +9481,7 @@ get_condition (rtx jump, rtx *earliest, int allow_cc_mode)
       && XEXP (XEXP (SET_SRC (set), 2), 0) == JUMP_LABEL (jump);
 
   return canonicalize_condition (jump, cond, reverse, earliest, NULL_RTX,
-				 allow_cc_mode);
+				 allow_cc_mode, valid_at_insn_p);
 }
 
 /* Similar to above routine, except that we also put an invariant last
@@ -9479,7 +9490,7 @@ get_condition (rtx jump, rtx *earliest, int allow_cc_mode)
 rtx
 get_condition_for_loop (const struct loop *loop, rtx x)
 {
-  rtx comparison = get_condition (x, (rtx*) 0, false);
+  rtx comparison = get_condition (x, (rtx*) 0, false, true);
 
   if (comparison == 0
       || ! loop_invariant_p (loop, XEXP (comparison, 0))

gcc/predict.c

@@ -636,7 +636,7 @@ estimate_probability (struct loops *loops_info)
   FOR_EACH_BB (bb)
     {
       rtx last_insn = BB_END (bb);
-      rtx cond, earliest;
+      rtx cond;
       edge e;
 
       if (! can_predict_insn_p (last_insn))
@@ -681,7 +681,7 @@ estimate_probability (struct loops *loops_info)
 	    }
 	}
 
-      cond = get_condition (last_insn, &earliest, false);
+      cond = get_condition (last_insn, NULL, false, false);
       if (! cond)
 	continue;
 
@@ -1043,7 +1043,8 @@ expected_value_to_br_prob (void)
 		(lt r70, r71)
 	 Could use cselib to try and reduce this further.  */
       cond = XEXP (SET_SRC (pc_set (insn)), 0);
-      cond = canonicalize_condition (insn, cond, 0, NULL, ev_reg, false);
+      cond = canonicalize_condition (insn, cond, 0, NULL, ev_reg,
+				     false, false);
       if (! cond || XEXP (cond, 0) != ev_reg
 	  || GET_CODE (XEXP (cond, 1)) != CONST_INT)
 	continue;