RFR: 8270446: Remove the MemBarNode that has been optimized from the current block

Wed Jul 14 07:41:28 UTC 2021

Hi all,
aarch64 and mips64 also had an optimization to merge two memory barrier instructions. But when I use the args -XX:+UnlockDiagnosticVMOptions -XX:+PrintOptoAssembly, I see some information like the following 

1a0 membar_release 
            dmb ish 
1a4 membar_release 
            dmb ish 
1a4 spill R19 -> R0 # spill size = 64 

Here, "1a4 membar_release" is actually optimized out . so I think it should be better to display it like this 

1a0 membar_release 
            dmb ish 
1a4 spill R19 -> R0 # spill size = 64

Please review this trivial change.

Thanks,
Sun Guoyun

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Commit messages:
 - 8270446: Remove the MemBarNode that has been optimized from the current block

Changes: https://git.openjdk.java.net/jdk/pull/4774/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4774&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8270446
  Stats: 7 lines in 1 file changed: 7 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4774.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4774/head:pull/4774

PR: https://git.openjdk.java.net/jdk/pull/4774