Hi,
PR 89546 is a nasty miscompilation bug that is in the compiler since
r247604 (May 2017) but is surprisingly hard to trigger. Since that
revision, SRA does not consider all aggregates that are assigned a value
in a gimple assignment statement from another aggregate as automatically
containing data. Instead, it records existence of such assignments and
then propagates this information from RHSs to LHSs in a simple queue
driven algorithm. That of course relies on the fact that whenever a
part of a LHSs is marked as containing data, all relevant parts of that
aggregate which are on the RHS of some other assignment are re-queued.
Well, it turns out I forgot to add that to one spot where that has to be
done.
Fixed with the patch below. Bootstrapped and tested on x86_64-linux.
OK for trunk and gcc 8?
Thanks,
Martin
2019-03-14 Martin Jambor <mjam...@suse.cz>
PR tree-optimization/89546
* tree-sra.c (propagate_subaccesses_across_link): Requeue new_acc if
any propagation to its children took place.
testsuite/
* gcc.dg/tree-ssa/pr89546.c: New test.
---
gcc/testsuite/gcc.dg/tree-ssa/pr89546.c | 100 ++++++++++++++++++++++++
gcc/tree-sra.c | 8 +-
2 files changed, 106 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr89546.c
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr89546.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr89546.c
new file mode 100644
index 00000000000..c4645ae1858
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr89546.c
@@ -0,0 +1,100 @@
+/* { dg-do run } */
+/* { dg-options "-O" } */
+
+struct I
+{
+ int i;
+};
+
+struct A
+{
+ struct I i1;
+ struct I i2;
+ struct I i3;
+};
+
+struct B
+{
+ struct I i0;
+ struct A a;
+};
+
+struct C
+{
+ struct I i00;
+ struct B b;
+};
+
+volatile int v;
+
+void __attribute__((noipa))
+consume_i (struct I i)
+{
+ v = i.i;
+}
+
+void __attribute__((noipa))
+consume_a (struct A a)
+{
+ v = a.i1.i;
+}
+
+void __attribute__((noipa))
+consume_b (struct B b)
+{
+ v = b.a.i1.i;
+}
+
+void __attribute__((noipa))
+consume_c (struct C c)
+{
+ v = c.b.a.i1.i;
+}
+
+
+
+
+int __attribute__((noipa))
+foo (struct I input)
+{
+ struct I i1, i2, i3;
+ struct A a1, a2, a3;
+ struct B b1;
+ struct C c;
+
+ i1 = input;
+ a1.i1 = i1;
+ b1.a = a1;
+
+ i2.i = 1;
+ b1.i0 = i2;
+
+ c.b = b1;
+
+ a2 = c.b.a;
+ a3 = a2;
+ i3 = a3.i1;
+
+ int t = c.b.i0.i;
+ a2.i3.i = 4;
+ consume_i (i1);
+ consume_i (i2);
+ consume_b (b1);
+ consume_a (a1);
+ consume_a (a2);
+ consume_a (a3);
+ consume_c (c);
+
+ return i3.i + t;
+}
+
+int
+main (int argc, char *argv[])
+{
+ struct I s;
+ s.i = 1234;
+ int i = foo (s);
+ if (i != 1235)
+ __builtin_abort ();
+ return 0;
+}
diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
index ca3858d5fc7..fd51a3d0323 100644
--- a/gcc/tree-sra.c
+++ b/gcc/tree-sra.c
@@ -2752,8 +2752,12 @@ propagate_subaccesses_across_link (struct access *lacc,
struct access *racc)
rchild->grp_hint = 1;
new_acc->grp_hint |= new_acc->grp_read;
- if (rchild->first_child)
- ret |= propagate_subaccesses_across_link (new_acc, rchild);
+ if (rchild->first_child
+ && propagate_subaccesses_across_link (new_acc, rchild))
+ {
+ ret = 1;
+ add_access_to_work_queue (new_acc);
+ }
}
else
{
--
2.21.0
