[jdk11u-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 jdk11u. jdk11u can benefit from this fix and having more accurate limit type information.

The jdk17u patch does not apply cleanly because of the following:

 * src/hotspot/share/opto/addnode.hpp
   * 11u does not have 8223347. Manually backported the MaxLNode/MinLNode class.

 * src/hotspot/share/opto/macro.cpp
   * The 11u backport of 8275330 does not add n->Opcode() == Op_Opaque4 to the assertion. Manually applied the change.

 * src/hotspot/share/opto/convertnode.cpp
   * 11u does not have 8256730 so the context is different. Manually applied the change.

 * src/hotspot/share/opto/loopTransform.cpp
   * 11u does not have 8301074 (replace of NULL with nullptr) so the change does not apply cleanly. Manually applied the change.
   * 11u does not have 8273115, so the context is different.
   * The 11u backport of 8262017 has "set_subtree_ctrl(inner_result_long);" instead of "set_subtree_ctrl(inner_result_long, false);" so the context is different.

In addition, the following changes were made:

 * C++11 lambda functions is_clamp and is_sub_con replaced with static equivalents.

 * nullptr replaced with NULL

No regressions observed in hotspot:tier1.

Thanks,
Martin.-

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

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Commit messages:
 - Backport cc894d849aa5f730d5a806acfc7a237cf5170af1

Changes: https://git.openjdk.org/jdk11u-dev/pull/2814/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2814&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303466
  Stats: 383 lines in 9 files changed: 321 ins; 49 del; 13 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2814.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2814/head:pull/2814

PR: https://git.openjdk.org/jdk11u-dev/pull/2814