RFR: 8325495: C2: implement optimization for series of Add of unique value [v2]

[Christian Hagedorn]

On Mon, 16 Sep 2024 21:04:14 GMT, Kangcheng Xu <kxu at openjdk.org> wrote:

> Please note, in the case of TestLargeTreeOfSubNodes with flags mentioned above, the compilation is skipped without a large enough -XX:MaxLabelRootDepth. This is the same behaviour as the current master.

Have you found out why this is the case? I thought that the original fix wanted to fix the problem of running out of nodes.

I gave your patch another spin. We still see various failures and timeouts. For example:

`compiler/intrinsics/sha/TestDigest.java` times out with various flag combinations (for example `-server -Xmixed`). Here is the stack at the timeout:


Thread 7 (Thread 0x7fc808490700 (LWP 22433)):
#0  0x00007fc80d648051 in Node::find_integer_type(BasicType) const () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#1  0x00007fc80c793214 in AddNode::extract_base_operand_from_serial_additions(PhaseGVN*, Node*, Node**, int) () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#2  0x00007fc80c79306c in AddNode::extract_base_operand_from_serial_additions(PhaseGVN*, Node*, Node**, int) () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
...
#90 0x00007fc80c79306c in AddNode::extract_base_operand_from_serial_additions(PhaseGVN*, Node*, Node**, int) () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#91 0x00007fc80c793082 in AddNode::extract_base_operand_from_serial_additions(PhaseGVN*, Node*, Node**, int) () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#92 0x00007fc80c79306c in AddNode::extract_base_operand_from_serial_additions(PhaseGVN*, Node*, Node**, int) () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#93 0x00007fc80c793351 in AddNode::convert_serial_additions(PhaseGVN*, bool, BasicType) () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#94 0x00007fc80c7937c5 in AddNode::IdealIL(PhaseGVN*, bool, BasicType) () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#95 0x00007fc80d73ea47 in PhaseGVN::transform(Node*) () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#96 0x00007fc80d715296 in Parse::do_one_bytecode() () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#97 0x00007fc80d7029ca in Parse::do_one_block() () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#98 0x00007fc80d703e86 in Parse::do_all_blocks() () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
#99 0x00007fc80d707738 in Parse::Parse(JVMState*, ciMethod*, float) () from /opt/mach5/mesos/work_dir/jib-master/install/2024-09-17-0714032.christian.hagedorn.jdk-test/linux-x64-debug.jdk/jdk-24/fastdebug/lib/server/libjvm.so
...


I'm also seeing the live node limit assert with test

applications/ctw/modules/java_desktop.java

and flags:

-ea -esa -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -server -XX:-TieredCompilation -Djava.awt.headless=true	

Assert hit:

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (/opt/mach5/mesos/work_dir/slaves/a20696e7-ae7d-4d37-8e9c-83f99ef002cb-S27847/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/118d2aab-d4da-49da-972c-f7b6fd5b5eee/runs/4c2607c3-6f9f-49ea-8d16-a0fb44652951/workspace/open/src/hotspot/share/opto/node.cpp:79), pid=305278, tid=305301
#  assert(C->live_nodes() <= C->max_node_limit()) failed: Live Node limit exceeded limit
#
# JRE version: Java(TM) SE Runtime Environment (24.0) (fastdebug build 24-internal-2024-09-17-0714032.christian.hagedorn.jdk-test)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 24-internal-2024-09-17-0714032.christian.hagedorn.jdk-test, mixed mode, sharing, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V  [libjvm.so+0x146c697]  Node::verify_construction()+0x1a7

-------------

PR Comment: https://git.openjdk.org/jdk/pull/20754#issuecomment-2355041639