Fix ia64-linux miscompilation or tcl/generic/tclCompExpr.c

	* loop.c (check_final_value): Check for biv use before checking for
	giv use.  Check for both biv and giv uses.  Always set last_giv_use
	if there is a giv use.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@36104 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 12 insertions, 6 deletions

diff --git a/gcc/loop.c b/gcc/loop.c
index 5c70055d265..c5e5c4c2ccb 100644
--- a/gcc/loop.c
+++ b/gcc/loop.c
@@ -5677,19 +5677,25 @@ check_final_value (loop, v)
 	  if (GET_CODE (p) == INSN || GET_CODE (p) == JUMP_INSN
 	      || GET_CODE (p) == CALL_INSN)
 	    {
-	      if (biv_increment_seen)
+	      /* It is possible for the BIV increment to use the GIV if we
+		 have a cycle.  Thus we must be sure to check each insn for
+		 both BIV and GIV uses, and we must check for BIV uses
+		 first.  */
+
+	      if (! biv_increment_seen
+		  && reg_set_p (v->src_reg, PATTERN (p)))
+		biv_increment_seen = 1;
+		
+	      if (reg_mentioned_p (v->dest_reg, PATTERN (p)))
 		{
-		  if (reg_mentioned_p (v->dest_reg, PATTERN (p)))
+		  if (biv_increment_seen)
 		    {
 		      v->replaceable = 0;
 		      v->not_replaceable = 1;
 		      break;
 		    }
+		  last_giv_use = p;
 		}
-	      else if (reg_set_p (v->src_reg, PATTERN (p)))
-		biv_increment_seen = 1;
-	      else if (reg_mentioned_p (v->dest_reg, PATTERN (p)))
-		last_giv_use = p;
 	    }
 	}