[C2] Backport JDK-8010500: Possible null pointer dereference at hotspot/src/share/vm/opto/loopnode.hpp

Summary:  Added NULL check for loopnode() in get_pre_loop_end()
Backport the fix for JDK-8010500 (https://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/4e7ee57b57bf) from OpenJDK.

Test Plan: none

Reviewed-by: kuaiwei, luchsh

Issue: https://github.com/alibaba/dragonwell8/issues/13

Summary:
  Port jwarmup to dragonwell 8u hotspot

ref T19299187

Test Plan:
test/hotspot/jtreg/jwarmup/Issue11272598.java
test/hotspot/jtreg/jwarmup/TestDisableNCE.java
test/hotspot/jtreg/jwarmup/TestNotDeoptJITMethod.sh
test/hotspot/jtreg/jwarmup/issue9780156.sh
test/hotspot/jtreg/jwarmup/TestEagerCompilation.java
test/hotspot/jtreg/jwarmup/TestNotifyDeopt.sh
test/hotspot/jtreg/jwarmup/TestCheckIfCompilationIsComplete.sh
test/hotspot/jtreg/jwarmup/TestFlagAssertion.java
test/hotspot/jtreg/jwarmup/TestReadLogfile.java
test/hotspot/jtreg/jwarmup/TestClassInitChain.java
test/hotspot/jtreg/jwarmup/TestLogFlush.java
test/hotspot/jtreg/jwarmup/TestRecordNullMethodCounter.java
test/hotspot/jtreg/jwarmup/TestThrowInitializaitonException.java
test/hotspot/jtreg/jwarmup/TestDisableMethodData.sh
test/hotspot/jtreg/jwarmup/TestMethodRecorder.java
test/hotspot/jtreg/jwarmup/TestTieredCompilationInRecording.sh

Reviewers: 传胜, 三红, yumin.qi

Reviewed By: 传胜, 三红

Subscribers: 麦庶

Differential Revision: https://aone.alibaba-inc.com/code/D852146

Reviewers: 效山, 芳玺, 传胜, 三红, yumin.qi

Reviewed By: 三红, 芳玺, 效山, 卓仁

Differential Revision: https://aone.alibaba-inc.com/code/D815657

Reviewed-by: kvn

Summary: convert the assert into compilation check which will skip superword optimization
Reviewed-by: roland, thartmann

Reviewed-by: thartmann, kvn

Reviewed-by: kvn

--HG--
extra : rebase_source : 51bb75f94058cf96cda1ea902645358e4c3a41fe

Reviewed-by: thartmann
Contributed-by: jitao8@huawei.com

Reviewed-by: kvn, thartmann

--HG--
extra : rebase_source : e1af5b86db38ac1b7ed27b4f39be267bb8b27d0e

Reviewed-by: neliasso, rkennke, dlong

Reviewed-by: andrew, phh

Summary: Implement _lh_array_tag_type_value as const, not enum.
Reviewed-by: vlivanov, minqi

Summary: Avoided collecting unaligned stores in Initialize node by making can_capture_store return false for same
Reviewed-by: dlong, kvn, vlivanov

Reviewed-by: mdoerr, goetz
Contributed-by: NBruno Rosa &lt;bruno.rosa@eldorado.org.br&gt;, Gustavo Serra Scalet &lt;gustavo.scalet@eldorado.org.br&gt;, Igor Nunes &lt;igor.nunes@eldorado.org.br&gt;, Martin Doerr <martin.doerr@sap.com>

Summary: Guard against regions degraded to copies.
Reviewed-by: kvn

Reviewed-by: shade, roland

Reviewed-by: neliasso, kvn

Reviewed-by: kvn

8172850: Anti-dependency on membar causes crash in register allocator due to invalid instruction scheduling
Summary: Regression test and additional asserts. The problem is fixed by 8087341.
Reviewed-by: kvn

8164480: Crash with assert(handler_address == SharedRuntime::compute_compiled_exc_handler(..) failed: Must be the same
Summary: Exception checking code needs to handle pre-allocated exceptions.
Reviewed-by: thartmann, kvn

Summary: Don't split if all edges will be moved to new phi
Reviewed-by: kvn

Summary: Fixed memory counting in compiler (C2)
Reviewed-by: adinn, cjplummer, kvn

Reviewed-by: kvn

Summary: CCP computes wrong type for CountedLoop iv Phi
Reviewed-by: kvn

Summary: Change TypeF:eq and TypeD:eq to compare NaN values using a bitwise comparison.
Reviewed-by: kvn
Contributed-by: NStefan Anzinger <stefan.anzinger@oracle.com>

Reviewed-by: kvn

Summary: Added required explicit NULL checks
Reviewed-by: thartmann, kvn

Summary: Fixed a missing null check on the return value of AddPNode::Ideal_base_and_offset() found by Parfait.
Reviewed-by: kvn

Summary: Fixed a missing null check on n->in(0) found by Parfait.
Reviewed-by: kvn

Summary: Fixed a missing null check on the return value of MachNodeGenerator() found by Parfait.
Reviewed-by: kvn

Summary: Fixed a missing null check on the return value of InitializeNode::allocation() found by Parfait.
Reviewed-by: zmajo

Reviewed-by: kvn, vlivanov, dlong, rhalade, mschoene, iignatyev

Reviewed-by: kvn, vlivanov, dlong, rhalade, mschoene, iignatyev

Summary: Check values returned by ciMethodData::bci_to_data() where necessary.
Reviewed-by: kvn

Summary: Require equal bases when unaliasing offsets for raw accesses
Reviewed-by: thartmann, kvn

Reviewed-by: kvn

Reviewed-by: kvn

Reviewed-by: kevinw, vlivanov

Reviewed-by: kevinw, vlivanov

Reviewed-by: kvn, thartmann