[8u] RFR: 8233023: assert(Opcode() == mem->Opcode() || phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw) failed: no mismatched stores, except on raw memory

[Roland Westrelin]

Hi Severin,

Thanks for taking care of this.

> Could I please get a review of this 8u only issue? The reason a
> fastdebug build of latest OpenJDK 8u asserts for the dec-tree benchmark
> of the renaissance suite is because the 8u backport of JDK-8140309 was
> missing this hunk from JDK 9[1]:
>
> +             (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
> +             (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
>
> I had a closer look and there doesn't seem to be missing anything else.
> The proposed fix is to amend the assert condition in the appropriate
> place, which brings 8u in line with JDK 9 code where the failure isn't
> observed.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8233023
> webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8233023/01/webrev/

Isn't this:

@@ -3213,6 +3221,9 @@
 // within the initialized memory.
 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
   const int FAIL = 0;
+  if (st->is_unaligned_access()) {
+    return FAIL;
+  }
   if (st->req() != MemNode::ValueIn + 1)
     return FAIL;                // an inscrutable StoreNode (card mark?)
   Node* ctl = st->in(MemNode::Control);

also missing from the 8140309?

It must be armless because nothing sets _unaligned_access AFAICT but
given the unaligned access part of the patch was backported I think we
should keep it consistent.

Also, 

+             (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode

is not from 8140309 but from 8080289. We're not going to backport it and
that line is unrelated to the change so backporting it sounds good. But
while doing this, we should backport the other changes to that assert
from 8080289 as well.

+             st->Opcode() == Op_StoreVector ||
+             Opcode() == Op_StoreVector ||

Roland.