Hi Richard,
Thanks for the review.
On 07/10/16 20:11, Richard Biener wrote:
On Fri, Oct 7, 2016 at 12:00 AM, kugan
<kugan.vivekanandara...@linaro.org> wrote:
Hi,
In vrp intersect_ranges, Richard recently changed it to create integer value
ranges when it is integer singleton.
Maybe we should do the same when the other range is a complex ranges with
SSA_NAME (like [x+2, +INF])?
Attached patch tries to do this. There are cases where it will be beneficial
as the testcase in the patch. (For this testcase to work with Early VRP, we
need the patch posted at
https://gcc.gnu.org/ml/gcc-patches/2016-10/msg00413.html)
Bootstrapped and regression tested on x86_64-linux-gnu with no new
regressions.
This is not clearly a win, in fact it can completely lose an ASSERT_EXPR
because there is no way to add its effect back as an equivalence. The
current choice of always using the "left" keeps the ASSERT_EXPR range
and is able to record the other range via an equivalence.
How about changing the order in Early VRP when we are dealing with the
same SSA_NAME in inner and outer scope. Here is a patch that does this.
Is this OK if no new regressions?
Thanks,
Kugan
My thought on this was that we need to separate "ranges" and associated
SSA names so we can introduce new ranges w/o the need for an SSA name
(and thus we can create an equivalence to the ASSERT_EXPR range).
IIRC I started on this at some point but never finished it ...
Richard.
Thanks,
Kugan
gcc/testsuite/ChangeLog:
2016-10-07 Kugan Vivekanandarajah <kug...@linaro.org>
* gcc.dg/tree-ssa/evrp6.c: New test.
gcc/ChangeLog:
2016-10-07 Kugan Vivekanandarajah <kug...@linaro.org>
* tree-vrp.c (intersect_ranges): If we failed to handle
the intersection and the other range involves computation with
symbolic values, choose integer range if available.
>From 54e92b7ddc47f6986e4dc79402d6808bb9c30c69 Mon Sep 17 00:00:00 2001
From: Kugan Vivekanandarajah <kugan.vivekanandara...@linaro.org>
Date: Sat, 8 Oct 2016 15:09:09 +1100
Subject: [PATCH 4/7] Revese value range before calling interset_range
---
gcc/testsuite/gcc.dg/tree-ssa/evrp6.c | 22 ++++++++++++++++++++++
gcc/tree-vrp.c | 16 +++++++++++++++-
2 files changed, 37 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/evrp6.c
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/evrp6.c b/gcc/testsuite/gcc.dg/tree-ssa/evrp6.c
new file mode 100644
index 0000000..35d4d74
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/evrp6.c
@@ -0,0 +1,22 @@
+
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp" } */
+
+extern void abort (void);
+
+int
+foo (int k, int j)
+{
+ if (j >= 10)
+ {
+ if (j < k)
+ {
+ k++;
+ if (k < 10)
+ abort ();
+ }
+ }
+
+ return j;
+}
+/* { dg-final { scan-tree-dump "\\\[12, \\+INF" "evrp" } } */
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 160adb5..c18c86f 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -10664,7 +10664,21 @@ evrp_dom_walker::try_add_new_range (tree op, tree_code code, tree limit)
extract_range_for_var_from_comparison_expr (op, code, op,
limit, &vr);
if (old_vr->type == VR_RANGE || old_vr->type == VR_ANTI_RANGE)
- vrp_intersect_ranges (&vr, old_vr);
+ {
+ if (range_int_cst_p (old_vr)
+ && !range_int_cst_p (&vr))
+ {
+ /* intersect_range will use the left value range to keeps the
+ ASSERT_EXPR range and record the other range via an equivalence.
+ In this case, we are tracking value_ranges for same SSA_NAME in
+ different scope, so reverse it for better result. */
+ value_range other_vr = vr;
+ vr = *old_vr;
+ vrp_intersect_ranges (&vr, &other_vr);
+ }
+ else
+ vrp_intersect_ranges (&vr, old_vr);
+ }
/* If we found any usable VR, set the VR to ssa_name and create a
PUSH old value in the stack with the old VR. */
if (vr.type == VR_RANGE || vr.type == VR_ANTI_RANGE)
--
2.7.4
