Summary: Add a use of the node cx to avoid it being destroyed.
Backport from JDK-8217359: https://bugs.java.com/bugdatabase/view_bug.do?bug_id=8217359
This patch of OpenJDK is available here: https://hg.openjdk.java.net/jdk/jdk12/rev/44f41693631f

Test Plan: test/compiler/c2/Test8217359.java

Reviewed-by: luchsh, kuaiwei

Issue: https://github.com/alibaba/dragonwell8/issues/11

Summary: Emit CastII to make narrow ConvI2L dependent on the corresponding range check.
Reviewed-by: kvn, roland

Reviewed-by: jrose, kvn

Summary: bad assumption on graph shape in CastIINode::Value if that part of the graph is becoming dead.
Reviewed-by: kvn

Summary: dead backbranch in main loop results in erroneous array access
Reviewed-by: kvn, iveresov

Summary: Emit CastII to make narrow ConvI2L dependent on the corresponding range check.
Reviewed-by: kvn, roland

Summary: Disabled narrowing of range check dependent CastIIs (either through the CastII(AddI) optimization or through CastIINode::Ideal).
Reviewed-by: vlivanov, kvn

Reviewed-by: kvn, thartmann

Summary: type methods shouldn't always operate on speculative part
Reviewed-by: kvn, twisti

Summary: Copyright year updated for files modified during 2013
Reviewed-by: twisti, iveresov

Reviewed-by: coleenp, mgerdin, hseigel

Summary: Add the -Wunused-function flag and remove a number of unused functions.
Reviewed-by: dholmes, coleenp, kvn

Summary: support of compress class pointers in the compilers.
Reviewed-by: kvn, twisti

Summary: Deleted placement new operator of Node - node(size_t, Compile *, int).
Reviewed-by: kvn, twisti
Contributed-by: bharadwaj.yadavalli@oracle.com

Summary: Remove PermGen, allocate meta-data in metaspace linked to class loaders, rewrite GC walking, rewrite and rename metadata to be C++ classes
Reviewed-by: jmasa, stefank, never, coleenp, kvn, brutisso, mgerdin, dholmes, jrose, twisti, roland
Contributed-by: Njmasa &lt;jon.masamitsu@oracle.com&gt;, stefank &lt;stefan.karlsson@oracle.com&gt;, mgerdin &lt;mikael.gerdin@oracle.com&gt;, never <tom.rodriguez@oracle.com>

Summary: use shorter instruction sequences for atomic add and atomic exchange when possible.
Reviewed-by: kvn, jrose

Summary: Take into account only stores captured by Initialize node. Added missing check for Top input in value() methods.
Reviewed-by: never

Summary: Integrate bsd-port/hotspot and macosx-port/hotspot changes as of 2011.09.29.
Reviewed-by: kvn, dholmes, never, phh
Contributed-by: NChristos Zoulas &lt;christos@zoulas.com&gt;, Greg Lewis &lt;glewis@eyesbeyond.com&gt;, Kurt Miller &lt;kurt@intricatesoftware.com&gt;, Alexander Strange &lt;astrange@apple.com&gt;, Mike Swingler &lt;swingler@apple.com&gt;, Roger Hoover &lt;rhoover@apple.com&gt;, Victor Hernandez &lt;vhernandez@apple.com&gt;, Pratik Solanki <psolanki@apple.com>

Summary: Replaced MakeDeps and the includeDB files with more standardized solutions.
Reviewed-by: coleenp, kvn, kamg

Summary: Hoist DecodeN instruction above null check
Reviewed-by: never, twisti

Summary: Change all the Sun copyrights to Oracle copyright
Reviewed-by: ohair

Summary: Avoid ideal transformation ping-pong between AddPNode::Ideal() and CastX2PNode::Ideal().
Reviewed-by: cfang

Summary: Update copyright for files that have been modified in 2009, up to 07/09
Reviewed-by: tbell, ohair

Summary: These methods can be instrinsified by using bit scan, bit test, and population count instructions.
Reviewed-by: kvn, never

Summary: Don't perform CMOVE identity optimization for floating point types
Reviewed-by: kvn, never

Summary: Use zero based compressed oops if java heap is below 32gb and unscaled compressed oops if java heap is below 4gb.
Reviewed-by: never, twisti, jcoomes, coleenp

Summary: I have collected some typos I have found while looking at the code.
Reviewed-by: kvn, never

Summary: Push DecodeN node below the Null check to the non-null path to use the mach node without 0 test.
Reviewed-by: rasbold, never

Summary: The result of step_through_mergemem() and remove_dead_region() is not checked in some cases.
Reviewed-by: never

Summary: Update copyright year for files that have been modified in 2008
Reviewed-by: ohair, tbell

Summary: Remove DecodeNNode::decode() and EncodePNode::encode() methods.
Reviewed-by: rasbold, never

Summary: verify the adr_type of a mach node was not changed
Reviewed-by: rasbold, never

Summary: Generate addresses and implicit null checks with narrow oops to avoid decoding.
Reviewed-by: jrose, never

6703890: Compressed Oops: add LoadNKlass node to generate narrow oops (32-bits) compare instructions
Summary: Add LoadNKlass and CMoveN nodes, use CmpN and ConN nodes to generate narrow oops compare instructions.
Reviewed-by: never, rasbold

Summary: fix several problems in C2 related to Escape Analysis and Compressed Oops.
Reviewed-by: never, jrose

Summary: 64-bits VM crashes with -XX:+AggresiveOpts (Escape Analysis + Compressed Oops)
Reviewed-by: never, sgoldman

Summary: Compressed oops in instances, arrays, and headers. Code contributors are coleenp, phh, never, swamyv
Reviewed-by: jmasa, kamg, acorn, tbell, kvn, rasbold

Summary: this optimization causes problems (sizes of Load and Store nodes do not match) for objects initialization code and Escape Analysis
Reviewed-by: jrose, never