JDK-8278230 : C2: Improve control of pinned loads split through phis to enable loop predication later
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 18
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • Submitted: 2021-12-03
  • Updated: 2021-12-03
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Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availability Release.

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Other
tbdUnresolved
Related Reports
Relates :  
JDK-8277529 - SIGSEGV in C2 CompilerThread Node::rematerialize() compiling Packet::readUnsignedTrint
Relates :  
JDK-8272574 - C2: assert(false) failed: Bad graph detected in build_loop_late
Description
The fix attempt for JDK-8272574 relied on improving the load split through phi optimization by rewiring pinned loads less conservatively. This, however, was not done correctly (JDK-8277529). The fix for JDK-8277529 reverts the improved handling of JDK-8272574 because it did not fix the original root cause. This RFE should revisit the idea of JDK-8272574 to improve the control of pinned loads that are split through phis such that they do not end up between a loop and the predicates which prevents the application of loop predication.