[11u] 8263361: Incorrect arraycopy stub selected by C2 for SATB collectors

[Hohensee, Paul]

Lgtm.

Thanks,
Paul

-----Original Message-----
From: jdk-updates-dev <jdk-updates-dev-retn at openjdk.java.net> on behalf of Roland Westrelin <rwestrel at redhat.com>
Date: Thursday, April 15, 2021 at 9:00 AM
To: "jdk-updates-dev at openjdk.java.net" <jdk-updates-dev at openjdk.java.net>
Subject: [11u] 8263361: Incorrect arraycopy stub selected by C2 for SATB collectors

Original bug:
  https://bugs.openjdk.java.net/browse/JDK-8263361
  https://github.com/openjdk/jdk/commit/5d87a219

Original patch does not apply cleanly to 11u, because context differs
for some files but patch is otherwise identical. Failed hunks are below.

11u webrev:
  https://cr.openjdk.java.net/~roland/8263361.11u/webrev.00/

Testing: x86_64 build, tier1

Thanks,
Roland.

src/hotspot/share/opto/library_call.cpp.rej
--- library_call.cpp
+++ library_call.cpp
@@ -4143,8 +4143,8 @@ bool LibraryCallKit::inline_native_clone(bool is_virtual) {
           PreserveJVMState pjvms2(this);
           set_control(is_obja);
           // Generate a direct call to the right arraycopy function(s).
-          Node* alloc = tightly_coupled_allocation(alloc_obj, NULL);
-          ArrayCopyNode* ac = ArrayCopyNode::make(this, true, obj, intcon(0), alloc_obj, intcon(0), obj_length, alloc != NULL, false);
+          // Clones are always tightly coupled.
+          ArrayCopyNode* ac = ArrayCopyNode::make(this, true, obj, intcon(0), alloc_obj, intcon(0), obj_length, true, false);
           ac->set_clone_oop_array();
           Node* n = _gvn.transform(ac);
           assert(n == ac, "cannot disappear");

src/hotspot/share/opto/macroArrayCopy.cpp.rej
--- macroArrayCopy.cpp
+++ macroArrayCopy.cpp
@@ -660,11 +670,10 @@ Node* PhaseMacroExpand::generate_arraycopy(ArrayCopyNode *ac, AllocateArrayNode*
     Node* local_ctrl = *ctrl;
     MergeMemNode* local_mem = MergeMemNode::make(mem);
     transform_later(local_mem);
-
     is_partial_array_copy = generate_unchecked_arraycopy(&local_ctrl, &local_mem,
                                                          adr_type, copy_type, disjoint_bases,
                                                          src, src_offset, dest, dest_offset,
-                                                         ConvI2X(copy_length), dest_uninitialized);
+                                                         ConvI2X(copy_length), acopy_to_uninitialized);

     // Present the results of the fast call.
     result_region->init_req(fast_path, local_ctrl);