[aarch64-port-dev ] RFR: 8144587: aarch64: generate vectorized MLA/MLS instructions

[Felix Yang]

Hi,

  I have corrected the webrev issues in my previous mail. Thanks Edward for
providing the help.
  Now I am resending this mail:

  Can someone help review and sponsor this code generation improvement for
aarch64 port?
  Bug: https://bugs.openjdk.java.net/browse/JDK-8144587
  Webrev: http://cr.openjdk.java.net/~fyang/8144587/webrev.02

  The hotspot/test/compiler/loopopts/superword/SumRed_Int.java can server
as a test case.
  With this patch, the following code snippet by C2:
    0x0000007f6cec12cc: mul v19.4s, v16.4s, v17.4s
    0x0000007f6cec12d0: mul v16.4s, v16.4s, v18.4s
    0x0000007f6cec12d4: mul v17.4s, v18.4s, v17.4s
    0x0000007f6cec12d8: add v16.4s, v19.4s, v16.4s
    0x0000007f6cec12dc: add v16.4s, v16.4s, v17.4s
  will be further optimized into:
    0x0000007f9cdb86dc: mul      v19.4s, v16.4s, v17.4s
    0x0000007f9cdb86e0: mla      v19.4s, v16.4s, v18.4s
    0x0000007f9cdb86e4: mla      v19.4s, v17.4s, v18.4s

  About 13% performance gain achieved for the test case on my aarch64
server.
  Tested with jtreg hotspot & langtools.  Results are the same before and
after.
  Is it OK to push?

Felix,
Thanks for your help.