RFR: 8270459: Conflict inlining decisions by C1/C2 with the same CompileCommand

[Jie Fu]

Hi all,

Conflict inlining decisions can be observed by C1/C2 with the same CompileCommand.
And I came across this situation while I was analyzing a performance issue using the jmh, which made me quite confused.

For the example in the JBS.

     28    1 %     3       TestInline::main @ 11 (43 bytes)
                              @ 23   TestInline::caller (4 bytes)   disallowed by CompileCommand
     29    2       3       TestInline::main (43 bytes)
                              @ 23   TestInline::caller (4 bytes)   disallowed by CompileCommand
     31    3 %     4       TestInline::main @ 11 (43 bytes)
     33    1 %     3       TestInline::main @ 11 (43 bytes)   made not entrant
                              @ 23   TestInline::caller (4 bytes)   force inline by CompileCommand


This can be easily reproduced by specifying both the `inline` and `dontinline` compile commands for a method.

   -XX:CompileCommand=inline,TestInline::caller \
   -XX:CompileCommand=dontinline,TestInline::caller \


The fix will ignore the inline/not-inline directives if both the `inline` and `dontinline` compile commands are specified for a method.

Effect of the patch:

     27    1 %     3       TestInline::main @ 11 (43 bytes)
                              @ 23   TestInline::caller (4 bytes)   inline
     28    2       3       TestInline::main (43 bytes)
                              @ 23   TestInline::caller (4 bytes)   inline
     28    3 %     4       TestInline::main @ 11 (43 bytes)
     30    1 %     3       TestInline::main @ 11 (43 bytes)   made not entrant
                              @ 23   TestInline::caller (4 bytes)   inline (hot)
     31    3 %     4       TestInline::main @ 11 (43 bytes)   made not entrant


Testing:
  - tier 1~3 on Linux/x64, no regression

Thanks.
Best regards,
Jie

-------------

Commit messages:
 - 8270459: Conflict inlining decisions by C1/C2 with the same CompileCommand

Changes: https://git.openjdk.java.net/jdk/pull/4780/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4780&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8270459
  Stats: 75 lines in 2 files changed: 73 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4780.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4780/head:pull/4780

PR: https://git.openjdk.java.net/jdk/pull/4780