RFR: 8153837 : aarch64: handle special cases for MaxINode & MinINode

Felix Yang felix.yang at linaro.org
Fri Apr 8 14:36:02 UTC 2016


    Please review webrev: *http://cr.openjdk.java.net/~fyang/8153837/webrev.00/
    JIRA Issue:
    Patch handles code generation for special cases where one arg is -1/0/1
of MaxINode & MinINode eliminating one extra mov instruction.
    As shown in the JIRA Issue, I saw some occurrences of the specail cases
in specJBB2005 and other benchmarks.
    The patch does something like this:

     min(x, 1)
     cmp x, 0
     csinc x, x, zr, le

     min(x, -1)
     cmp x, 0
     csinv x, x, zr, lt

     max(x, 1)
     cmp x, 0
     csinc x, x, zr, gt

     max(x, -1)
     cmp x, 0
     csinv x, x, zr, ge

    Tested with JTreg hotspot, langtools.  Is it OK?

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