PR optimization/12340

	* loop.h (struct induction): Document the new semantics
	of the 'same' field for bivs.
	* unroll.c (biv_total_increment): Don't count the same
	biv increment several times.
	(loop_iterations) [GENERAL_INDUCT]: Likewise.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@71859 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 11 insertions, 1 deletions

diff --git a/gcc/unroll.c b/gcc/unroll.c
index 084660ca11b..38659d461cb 100644
--- a/gcc/unroll.c
+++ b/gcc/unroll.c
@@ -2436,7 +2436,13 @@ biv_total_increment (const struct iv_class *bl)
       if (v->always_computable && v->mult_val == const1_rtx
 	  && ! v->maybe_multiple
 	  && SCALAR_INT_MODE_P (v->mode))
-	result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
+	{
+	  /* If we have already counted it, skip it.  */
+	  if (v->same)
+	    continue;
+
+	  result = fold_rtx_mult_add (result, const1_rtx, v->add_val, v->mode);
+	}
       else
 	return 0;
     }
@@ -3481,6 +3487,10 @@ loop_iterations (struct loop *loop)
 			return 0;
 		    }
 
+		  /* If we have already counted it, skip it.  */
+		  if (biv_inc->same)
+		    continue;
+
 		  offset -= INTVAL (biv_inc->add_val);
 		}
 	    }