JDK-8146792 : Predicate moved after partial peel may lead to broken graph
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 8u231,9
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2016-01-11
  • Updated: 2023-07-21
  • Resolved: 2016-01-13
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JDK 8 JDK 9 Other
8u251Fixed 9 b105Fixed openjdk8u252Fixed
Related Reports
Duplicate :  
JDK-8221605 - C2 crashed at PhaseIdealLoop::build_loop_late_post
Relates :  
JDK-8277529 - SIGSEGV in C2 CompilerThread Node::rematerialize() compiling Packet::readUnsignedTrint
Relates :  
JDK-8278231 - C2: Cleanup loop invariance handling for data nodes dependent on projection into the loop
Description
- partial peeling is applied to a loop
- the peeled section is optimized and leaves a pinned node between the loop predicates and the loop body but no control flow
- loop predicates are applied and a predicate that depends on the pinned node is moved out of the loop, before the pinned node, leading to a broken graph

ILW=H(crash)L(never seen in the wild)M(disable partial peel)=P3
Comments
Fix Request 8u What: Original patch applies to jdk8u with minor tweaks ( review thread: https://mail.openjdk.java.net/pipermail/jdk8u-dev/2019-August/009947.html ) Why: hotspot will always crash with the supplied trivial test case due to bad C2 graph Testing: full jtreg test succeeds with jdk8u fastdebug x86-64 build Risk: Low
22-01-2020
8u review approval: https://mail.openjdk.java.net/pipermail/jdk8u-dev/2020-January/010996.html
21-01-2020
For future reference (would have saved me some hours of searching/debugging..), the failure mode of this is "assert(false) failed: Bad graph detected in build_loop_late" (see JDK-8236755).
10-01-2020
URL: http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/2748d975045f User: lana Date: 2016-02-10 21:55:30 +0000
10-02-2016
URL: http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/2748d975045f User: roland Date: 2016-01-13 10:25:55 +0000
13-01-2016