RFR: 8278104: C1 should support the compiler directive 'BreakAtExecute'

[Guoxiong Li]

Hi all,

Currently, the directive `BreakAtExecute` is not effective at C1. And the `CompileCommand=break` doesn't break the compiled method, too. This patch unifies the `BreakAtExecute` and `CompileCommand=break` to the directive 'BreakAtExecute' and uses the directive 'BreakAtExecute' to identify whether a breakpoint should be added.

The test group `hotspot_compiler` passed locally.(linux x86_64 fastdebug)
And the pre-submit tests passed before submitting the PR.

Thanks for taking the time to review.

Best Regards,
-- Guoxiong

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Commit messages:
 - 8278104: C1 should support the compiler directive 'BreakAtExecute'

Changes: https://git.openjdk.java.net/jdk/pull/6807/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6807&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278104
  Stats: 26 lines in 8 files changed: 12 ins; 0 del; 14 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6807.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6807/head:pull/6807

PR: https://git.openjdk.java.net/jdk/pull/6807