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  1. JDK
  2. JDK-8067767

type inference performance regression

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    • b94
    • x86_64
    • linux
    • Verified

    Description

      FULL PRODUCT VERSION :
      java version "1.8.0_25"
      Java(TM) SE Runtime Environment (build 1.8.0_25-b17)
      Java HotSpot(TM) 64-Bit Server VM (build 25.25-b02, mixed mode)


      ADDITIONAL OS VERSION INFORMATION :
      x86_64 GNU/Linux

      A DESCRIPTION OF THE PROBLEM :
      Performing type inference of the following code is mucher slower with JDK 8.

      This may be related to the speculative attribution preformance issues described in JDK-8051946.

      Profiling shows that most of the time is spent inside Infer.checkWithinBounds. UndetVar.substBounds is called tens of thousands of times, and each call uses javac.util.List.diff(List). The diff implementation takes time quadratic to the size of the list.

      Fixing the diff implementation makes it way faster, but it's still slower than JDK 7.

      REGRESSION. Last worked in version 7u67

      ADDITIONAL REGRESSION INFORMATION:
      java version "1.7.0_67"
      Java(TM) SE Runtime Environment (build 1.7.0_67-b01)
      Java HotSpot(TM) 64-Bit Server VM (build 24.65-b04, mixed mode)


      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      Compile the attached program.

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      Compilation should succeed reasonably fast.
      ACTUAL -
      The compilation takes about a minute.

      REPRODUCIBILITY :
      This bug can be reproduced always.

      ---------- BEGIN SOURCE ----------
      class Test {

        static class Pair<A, B> {
          static <A, B> Pair<A, B> of(A a, B b) {
            throw new RuntimeException();
          }
        }

        static class List<T> {
          static <T> List<T> of(T... tx) {
            throw new RuntimeException();
          }
        }

        static final List<Pair<String, String>> PAIRS = List.of(
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"),
            Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"), Pair.of("a", "b"));
      }

      ---------- END SOURCE ----------

      CUSTOMER SUBMITTED WORKAROUND :
      The word-around is to stop using type inference:

      - static final List<Pair<String, String>> PAIRS = List.of(
      + static final List<Pair<String, String>> PAIRS = List.<Pair<String, String>>of(

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              vromero Vicente Arturo Romero Zaldivar
              webbuggrp Webbug Group
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                Created:
                Updated:
                Resolved: