[jdk8u-dev] RFR: 8303466: C2: failed: malformed control flow. Limit type made precise with MaxL/MinL

[Martin Balao]

Hi,

I would like to propose a backport of 8303466 [1] to jdk8u. jdk8u can benefit from this fix and having more accurate limit type information.

This pull request contains a backport of commit [8578e12c423ed61618e0b3ef81e5be3d18be1da2](https://github.com/openjdk/jdk11u-dev/commit/8578e12c423ed61618e0b3ef81e5be3d18be1da2) from the [openjdk/jdk11u-dev](https://github.com/openjdk/jdk11u-dev) repository.

This backport depends on [JDK-8262017](https://bugs.openjdk.org/browse/JDK-8262017).

The jdk11u patch does not apply cleanly because of the following:

 * hotspot/src/share/vm/opto/addnode.hpp
   * 8u does not have 8212043. Manually applied the change.

 * hotspot/src/share/vm/runtime/vmStructs.cpp
   * 8u does not have 8212043. Manually applied the change.

 * hotspot/src/share/vm/opto/macro.cpp
   * 8u does not have 8204210. Manually applied the change.
   * 8u does not have 8186027. Manually applied the change.

 * hotspot/src/share/vm/opto/loopTransform.cpp
   * 8u does not have 8223142. In addition, 8u does not have 8034812. Manually applied the change.
   * 8u does not have 8182299. Manually applied the change.

In addition, the following changes were made:

 * Nodes allocation follows the pattern "new (C) ..." instead of "new ...".

 * File locations were adjusted.

 * In addnode.cpp, 8u does not have 8284358 so the function "Node::set_req_X(uint i, Node *n, PhaseGVN *gvn)" is not available. Picked this function (declaration and definition) from 8284358.

 * In 8u, the jtreg VM prop vm.compiler2.enabled does not exist. C2 will likely be available and if the test were executed without C2, it should be harmless.

No regressions observed in hotspot:tier1.

Thanks,
Martin.-

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[1] - https://bugs.openjdk.org/browse/JDK-8303466

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

Commit messages:
 - Backport cc894d849aa5f730d5a806acfc7a237cf5170af1

Changes: https://git.openjdk.org/jdk8u-dev/pull/529/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=529&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303466
  Stats: 392 lines in 11 files changed: 329 ins; 49 del; 14 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/529.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/529/head:pull/529

PR: https://git.openjdk.org/jdk8u-dev/pull/529