RFR: 8278079: C2: expand_dtrace_alloc_probe doesn't take effect in macro.cpp

[Vladimir Kozlov]

On Fri, 3 Dec 2021 09:17:45 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

> > I think ExtendedDTraceProbes was originally designed for this purpose
> 
> Yes, if that's the case, I'm fine with the change. Otherwise, I would suggest to remove that flag. @vnkozlov, what do you think?

Yes, I agree with removal of `ExtendedDTraceProbes` flag.
It was first flag which was used in all places in HotSpot during development of DTrace support.
Based on changes I see for [6346964](https://bugs.openjdk.java.net/browse/JDK-6346964) it was replaced with new 3 flags:


^Ad D 1.300.1.1 06/03/13 11:39:20 km88527 802 801
^Ac Partial 6346964: Support dynamic enabling of extended DTrace probes

    } else if (match_option(option, "-XX:+ExtendedDTraceProbes", &tail)) {
#ifdef SOLARIS
      FLAG_SET_CMDLINE(bool, ExtendedDTraceProbes, true);
^AI 802
      FLAG_SET_CMDLINE(bool, DTraceMethodProbes, true);
      FLAG_SET_CMDLINE(bool, DTraceAllocProbes, true);
      FLAG_SET_CMDLINE(bool, DTraceMonitorProbes, true);
^AE 802


Actually the code guarded by `ExtendedDTraceProbes` in `macro.cpp` was removed in those changes but later it was restored during branches merge (wrong merge?).
<img width="994" alt="6346964_macro" src="https://user-images.githubusercontent.com/5215794/144651140-6df8b67f-024c-4ef8-8eff-dfb607dcd5e1.png">

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PR: https://git.openjdk.java.net/jdk/pull/6639