[PR 82363] Fix thinko in SRA subaccess propagation

[Richard Biener]

On October 2, 2017 7:19:19 PM GMT+02:00, Martin Jambor <mjambor@suse.cz> wrote:
>Hi,
>
>the following fixes a thinko in propagate_subaccesses_across_link.
>When we cannot copy over a tree of accesses of RHS to LHS because of
>some conflict, we must mark the whole LHS access (sub-)tree as
>potentially written, even when the RHS access describing this level is
>not, because some of its sub-accesses might be, which is exactly what
>happens in the PR.
>
>Bootstrapped and tested on x86_64-linux.  OK for trunk?

OK. 

Richard. 

>Thanks,
>
>Martin
>
>
>
>2017-10-02  Martin Jambor  <mjambor@suse.cz>
>
>	PR tree-optimization/82363
>	* tree-sra.c (propagate_subaccesses_across_link): In unrecoverable
>	mismatch, mark lacc written regardless of racc.
>
>	testsuite/
>	* gcc.dg/tree-ssa/pr82363.c: New test.
>---
>gcc/testsuite/gcc.dg/tree-ssa/pr82363.c | 50
>+++++++++++++++++++++++++++++++++
> gcc/tree-sra.c                          |  2 +-
> 2 files changed, 51 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr82363.c
>
>diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr82363.c
>b/gcc/testsuite/gcc.dg/tree-ssa/pr82363.c
>new file mode 100644
>index 00000000000..6652468976b
>--- /dev/null
>+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr82363.c
>@@ -0,0 +1,50 @@
>+/* { dg-do run } */
>+/* { dg-options "-O" } */
>+
>+struct A
>+{
>+  int b;
>+  int c;
>+  int d;
>+};
>+
>+struct E
>+{
>+  int f;
>+  int g:18;
>+  struct A h;
>+};
>+
>+struct I
>+{
>+  int b;
>+  int j;
>+  struct E k;
>+};
>+
>+int l, *m = &l;
>+
>+struct A n;
>+struct I o;
>+
>+void __attribute__ ((noipa))
>+test_l (void)
>+{
>+  if (l != 1)
>+    __builtin_abort ();
>+}
>+
>+int main ()
>+{
>+  while (1)
>+    {
>+      struct I q = { 0, 0, {0, 0, {1, 1, 1}}}, p = q, r = p, *s = &q;
>+      if (p.k.h.c)
>+        o = p;
>+      *m = r.k.h.d;
>+      n = (*s).k.h;
>+      break;
>+    }
>+  test_l ();
>+  return 0;
>+}
>diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
>index f5675edc7f1..bac593951e7 100644
>--- a/gcc/tree-sra.c
>+++ b/gcc/tree-sra.c
>@@ -2691,7 +2691,7 @@ propagate_subaccesses_across_link (struct access
>*lacc, struct access *racc)
> 	    }
> 	  else
> 	    {
>-	      if (rchild->grp_write && !lacc->grp_write)
>+	      if (!lacc->grp_write)
> 		{
> 		  ret = true;
> 		  subtree_mark_written_and_enqueue (lacc);