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  1. JDK
  2. JDK-6743900

frequency based block layout

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P3
    • Resolution: Fixed
    • Affects Version/s: hs14
    • Fix Version/s: hs14
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
    • Resolved In Build:
      b07
    • CPU:
      generic
    • OS:
      generic

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        Description

        The server compiler currently computes block frequencies based on branch estimates and probabilities collected from profiling data.

        The frequency data can be leveraged create a block layout that:
          - reduces the number of branches emitted
          - improves icache locality
          - rotates loops to end with a conditional branch
          - naturally moves uncommon code sequences out of line without using an arbitrary frequency cutoff

        While only modest improvement in performance should be expected, a reduction in the methods for which "spaghetti code" is emitted, should make assembly code more readable.

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                Assignee:
                rasbold Chuck Rasbold
                Reporter:
                rasbold Chuck Rasbold
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