JDK-8253524 : C2: Refactor code that clones predicates during loop unswitching
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 11,16
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2020-09-23
  • Updated: 2022-02-06
  • Resolved: 2020-09-24
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JDK 11 JDK 16
11.0.11-oracleFixed 16 b18Fixed
Description
During unswitching PhaseIdealLoop::create_slow_version_of_loop() calls PhaseIdealLoop::clone_predicates_to_unswitched_loop() twice, one for each loops, to clone some predicates above each loop. That code is fragile as it (implicitly) requires the fast loop to be processed first. I propose calling PhaseIdealLoop::clone_predicates_to_unswitched_loop() a single time and have it handle both loops in a single pass.
Comments
Fix Request Should get backported for parity with 11.0.11-oracle. Applies cleanly.
07-01-2021

Changeset: b1e2f026 Author: Roland Westrelin <roland@openjdk.org> Date: 2020-09-24 10:00:33 +0000 URL: https://git.openjdk.java.net/jdk/commit/b1e2f026
24-09-2020