JDK-8085832 : Optimize main and post loop out when pre loop is found empty
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 9
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2015-06-04
  • Updated: 2024-03-08
  • Resolved: 2015-06-10
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JDK 9
9 b70Fixed
Related Reports
Relates :  
JDK-8327423 - C2: assert(locate_pre_from_main(main_head) == cl) failed: bad main loop
Relates :  
JDK-8233529 - loopTransform.cpp:2984: Error: assert(p_f->Opcode() == Op_IfFalse) failed
Relates :  
JDK-8078866 - compiler/eliminateAutobox/6934604/TestIntBoxing.java assert(p_f->Opcode() == Op_IfFalse) failed
Description
In JDK-8078866, the pre loop is optimized out but the main/post loops are not. If the pre loop’s limit is still an opaque node, then the compiler has not been able to optimize the pre loop based on its limited number of iterations yet. I don’t see what optimization would remove stuff from the pre loop that wouldn’t have removed the same stuff from the initial loop, had it not been cloned. So it should be safe to remove the main and post loops.
Comments
URL: http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/421989a11af8 User: lana Date: 2015-06-20 18:07:53 +0000
20-06-2015
URL: http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/421989a11af8 User: roland Date: 2015-06-10 16:14:55 +0000
10-06-2015