Re: [PATCH PR81267]Rewrite into loop closed ssa form in case of any store-store chain

[Richard Biener]

On Mon, Jul 31, 2017 at 4:14 PM, Bin Cheng  wrote:
> Hi,
> This simple patch fixes the ICE by rewriting into loop closed ssa form in case
> of any store-store chain.  We maybe able to avoid that for some cases that
> eliminated stores only store loop invariant values, but only with more checks
> when inserting final store instructions.
> Bootstrap and test on x86_64 and AArch64 ongoing.  Is it OK?

Ok.

Thanks,
Richard.

> Thanks,
> bin
> 2017-07-31  Bin Cheng  
>
> PR tree-optimization/81627
> * tree-predcom.c (prepare_finalizers): Always rewrite into loop
> closed ssa form for store-store chain.
>
> gcc/testsuite/ChangeLog
> 2017-07-31  Bin Cheng  
>
> PR tree-optimization/81627
> * gcc.dg/tree-ssa/pr81627.c: New.

[PATCH PR81267]Rewrite into loop closed ssa form in case of any store-store chain

[Bin Cheng]

Hi,
This simple patch fixes the ICE by rewriting into loop closed ssa form in case
of any store-store chain.  We maybe able to avoid that for some cases that
eliminated stores only store loop invariant values, but only with more checks
when inserting final store instructions.
Bootstrap and test on x86_64 and AArch64 ongoing.  Is it OK?

Thanks,
bin
2017-07-31  Bin Cheng  

PR tree-optimization/81627
* tree-predcom.c (prepare_finalizers): Always rewrite into loop
closed ssa form for store-store chain.

gcc/testsuite/ChangeLog
2017-07-31  Bin Cheng  

PR tree-optimization/81627
* gcc.dg/tree-ssa/pr81627.c: New.From d366015187de926a8fe3248325b229bed99b27b5 Mon Sep 17 00:00:00 2001
From: Bin Cheng 
Date: Mon, 31 Jul 2017 11:16:44 +0100
Subject: [PATCH 2/2] pr81627-20170731.txt

---
 gcc/testsuite/gcc.dg/tree-ssa/pr81627.c | 28 
 gcc/tree-predcom.c  | 10 +-
 2 files changed, 33 insertions(+), 5 deletions(-)
 create mode 100755 gcc/testsuite/gcc.dg/tree-ssa/pr81627.c

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr81627.c 
b/gcc/testsuite/gcc.dg/tree-ssa/pr81627.c
new file mode 100755
index 000..7421c49
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr81627.c
@@ -0,0 +1,28 @@
+/* { dg-do run } */
+/* { dg-options "-O3 -fno-tree-loop-vectorize -fdump-tree-pcom-details" } */
+
+int a, b, c, d[6], e = 3, f;
+
+void abort (void);
+void fn1 ()
+{
+  for (b = 1; b < 5; b++)
+{
+  for (c = 0; c < 5; c++)
+d[b] = e;
+  if (a)
+f++;
+  d[b + 1] = 1;
+}
+}
+
+int main ()
+{
+  fn1 ();
+  if (d[0] != 0 || d[1] != 3 || d[2] != 3
+  || d[3] != 3 || d[4] != 3 || d[5] != 1)
+abort ();
+
+  return 0;
+}
+/* { dg-final { scan-tree-dump-times "Store-stores chain" 1 "pcom" } } */
diff --git a/gcc/tree-predcom.c b/gcc/tree-predcom.c
index f7a57a4..4538773 100644
--- a/gcc/tree-predcom.c
+++ b/gcc/tree-predcom.c
@@ -2983,11 +2983,11 @@ prepare_finalizers (struct loop *loop, vec 
chains)
   if (prepare_finalizers_chain (loop, chain))
{
  i++;
- /* We don't corrupt loop closed ssa form for store elimination
-chain if eliminated stores only store loop invariant values
-into memory.  */
- if (!chain->inv_store_elimination)
-   loop_closed_ssa |= (!chain->inv_store_elimination);
+ /* Be conservative, assume loop closed ssa form is corrupted
+by store-store chain.  Though it's not always the case if
+eliminated stores only store loop invariant values into
+memory.  */
+ loop_closed_ssa = true;
}
   else
{
-- 
1.9.1