Hi Jeff,
Thanks for looking into it.
On 6 July 2018 at 08:03, Jeff Law <l...@redhat.com> wrote:
> On 06/24/2018 08:41 PM, Kugan Vivekanandarajah wrote:
>> Hi Jeff,
>>
>> Thanks for the comments.
>>
>> On 23 June 2018 at 02:06, Jeff Law <l...@redhat.com> wrote:
>>> On 06/22/2018 03:11 AM, Kugan Vivekanandarajah wrote:
>>>> When we set niter with maybe_zero, currently final_value_relacement
>>>> will not happen due to expression_expensive_p not handling. Patch 1
>>>> adds this.
>>>>
>>>> With that we have the following optimized gimple.
>>>>
>>>> <bb 2> [local count: 118111601]:
>>>> if (b_4(D) != 0)
>>>> goto <bb 3>; [89.00%]
>>>> else
>>>> goto <bb 4>; [11.00%]
>>>>
>>>> <bb 3> [local count: 105119324]:
>>>> _2 = (unsigned long) b_4(D);
>>>> _9 = __builtin_popcountl (_2);
>>>> c_3 = b_4(D) != 0 ? _9 : 1;
>>>>
>>>> <bb 4> [local count: 118111601]:
>>>> # c_12 = PHI <c_3(3), 0(2)>
>>>>
>>>> I assume that 1 in b_4(D) != 0 ? _9 : 1; is OK (?) because when the
>>>> latch execute zero times for b_4 == 0 means that the body will execute
>>>> ones.
>>> ISTM that DOM ought to have simplified the conditional, unless there's
>>> some other way to get to bb3. We know that b_4 is nonzero and thus c_3
>>> must have the value _9.
>> As of now, dom is not optimizing it. With the attached hack, it can be made
>> to.
> What's strange is I'm not getting the c_3 = (b_4 != 0) ... in any of the
> dumps I'm looking at. Instead it's c_3 = _9, which is what I would
> expect since we know that b_4 != 0
>
>
> My tests have been on x86_64 and aarch64 linux targets. I've tried with
> patch#1 installed as well as with patch #1 and patch #2 together.
>
> What target, what flags and what patches do I need to see this?
You need the patch 1 (attaching) to get that. With Patch 2 in this
series, it will be optimized.
I haven't committed the patches yet as I am testing all the three
patches. I will commit after testing on current trunk.
Thanks,
Kugan
>
> Jeff
From 12263df77931aa55d205b9db470436848d762684 Mon Sep 17 00:00:00 2001
From: Kugan Vivekanandarajah <kugan.vivekanandara...@linaro.org>
Date: Fri, 22 Jun 2018 14:10:26 +1000
Subject: [PATCH 1/3] generate popcount when checked for zero
Change-Id: I951e6d487268b757cbdaa8dcf671ab1377490db6
---
gcc/gimplify.c | 2 +-
gcc/gimplify.h | 1 +
gcc/testsuite/gcc.dg/tree-ssa/pr64183.c | 2 +-
gcc/testsuite/gcc.target/i386/pr85073.c | 2 +-
gcc/tree-scalar-evolution.c | 12 ++++++++++++
5 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 48ac92e..c86ad1a 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -3878,7 +3878,7 @@ gimplify_pure_cond_expr (tree *expr_p, gimple_seq *pre_p)
EXPR is GENERIC, while tree_could_trap_p can be called
only on GIMPLE. */
-static bool
+bool
generic_expr_could_trap_p (tree expr)
{
unsigned i, n;
diff --git a/gcc/gimplify.h b/gcc/gimplify.h
index dd0e4c0..62ca869 100644
--- a/gcc/gimplify.h
+++ b/gcc/gimplify.h
@@ -83,6 +83,7 @@ extern enum gimplify_status gimplify_arg (tree *, gimple_seq *, location_t,
extern void gimplify_function_tree (tree);
extern enum gimplify_status gimplify_va_arg_expr (tree *, gimple_seq *,
gimple_seq *);
+extern bool generic_expr_could_trap_p (tree expr);
gimple *gimplify_assign (tree, tree, gimple_seq *);
#endif /* GCC_GIMPLIFY_H */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr64183.c b/gcc/testsuite/gcc.dg/tree-ssa/pr64183.c
index 7a854fc..50d0c5a 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr64183.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr64183.c
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-O3 -fno-tree-vectorize -fdump-tree-cunroll-details" } */
+/* { dg-options "-O3 -fno-tree-vectorize -fdisable-tree-sccp -fdump-tree-cunroll-details" } */
int bits;
unsigned int size;
diff --git a/gcc/testsuite/gcc.target/i386/pr85073.c b/gcc/testsuite/gcc.target/i386/pr85073.c
index 187102d..71a5d23 100644
--- a/gcc/testsuite/gcc.target/i386/pr85073.c
+++ b/gcc/testsuite/gcc.target/i386/pr85073.c
@@ -1,6 +1,6 @@
/* PR target/85073 */
/* { dg-do compile } */
-/* { dg-options "-O2 -mbmi" } */
+/* { dg-options "-O2 -mbmi -fdisable-tree-sccp" } */
int
foo (unsigned x)
diff --git a/gcc/tree-scalar-evolution.c b/gcc/tree-scalar-evolution.c
index 4b0ec02..8e29005 100644
--- a/gcc/tree-scalar-evolution.c
+++ b/gcc/tree-scalar-evolution.c
@@ -3508,6 +3508,18 @@ expression_expensive_p (tree expr)
return false;
}
+ if (code == COND_EXPR)
+ return (expression_expensive_p (TREE_OPERAND (expr, 0))
+ || (EXPR_P (TREE_OPERAND (expr, 1))
+ && EXPR_P (TREE_OPERAND (expr, 2)))
+ /* If either branch has side effects or could trap. */
+ || TREE_SIDE_EFFECTS (TREE_OPERAND (expr, 1))
+ || generic_expr_could_trap_p (TREE_OPERAND (expr, 1))
+ || TREE_SIDE_EFFECTS (TREE_OPERAND (expr, 0))
+ || generic_expr_could_trap_p (TREE_OPERAND (expr, 0))
+ || expression_expensive_p (TREE_OPERAND (expr, 1))
+ || expression_expensive_p (TREE_OPERAND (expr, 2)));
+
switch (TREE_CODE_CLASS (code))
{
case tcc_binary:
--
2.7.4
