Re: [PATCH 2/3][POPCOUNT] Check if zero check is done before entering the loop

[Kugan Vivekanandarajah <kugan dot vivekanandarajah at linaro dot org>]

Hi Richard,

Thanks for the review.

On 25 June 2018 at 20:02, Richard Biener <richard.guenther@gmail.com> wrote:
> On Fri, Jun 22, 2018 at 11:14 AM Kugan Vivekanandarajah
> <kugan.vivekanandarajah@linaro.org> wrote:
>>
>> gcc/ChangeLog:
>
> The canonical way is calling simplify_using_initial_conditions on the
> may_be_zero condition.
>
> Richard.
>
>> 2018-06-22  Kugan Vivekanandarajah  <kuganv@linaro.org>
>>
>>     * tree-ssa-loop-niter.c (number_of_iterations_popcount): If popcount
>>     argument is checked for zero before entering loop, avoid checking again.
Do you like the attached patch which does this.

Thanks,
Kugan

From 78cb0ea3d058f1d1db73f259825b8bb07eb1ca30 Mon Sep 17 00:00:00 2001
From: Kugan Vivekanandarajah <kugan.vivekanandarajah@linaro.org>
Date: Fri, 22 Jun 2018 14:11:28 +1000
Subject: [PATCH 2/3] in niter dont check for zero when it is alrealy checked

Change-Id: Ie94a35a1a3c2d8bdffd3dc54a94684c032efc7e0
---
 gcc/tree-ssa-loop-niter.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
index f5ffc0f..be0cff5 100644
--- a/gcc/tree-ssa-loop-niter.c
+++ b/gcc/tree-ssa-loop-niter.c
@@ -2596,10 +2596,15 @@ number_of_iterations_popcount (loop_p loop, edge exit,
 
   niter->niter = iter;
   niter->assumptions = boolean_true_node;
+
   if (adjust)
-    niter->may_be_zero = fold_build2 (EQ_EXPR, boolean_type_node, src,
+    {
+      tree may_be_zero = fold_build2 (EQ_EXPR, boolean_type_node, src,
 				      build_zero_cst
 				      (TREE_TYPE (src)));
+      niter->may_be_zero =
+	simplify_using_initial_conditions (loop, may_be_zero);
+    }
   else
     niter->may_be_zero = boolean_false_node;
 
-- 
2.7.4