RFR: 8281548: Add escape analysis tracing flag [v3]

[Jorn Vernee]

On Tue, 15 Feb 2022 07:37:47 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> Jorn Vernee has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:
>> 
>>  - Merge branch 'master' into TraceEA
>>  - Typo
>>    
>>    Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
>>  - Add missing newlines
>>  - Pass outputStream to dump_header
>>  - Remove redundant resource mark
>>  - Rewrite with reason string
>>  - format string warning
>>  - Add TraceEscapeAnalysis flag
>
> src/hotspot/share/opto/escape.hpp line 434:
> 
>> 432:   // Set the escape state of an object and its fields.
>> 433:   void set_escape_state(PointsToNode* ptn, PointsToNode::EscapeState esc
>> 434:                         DEBUG_ONLY(COMMA const char* reason="reason unknown")) {
> 
> Wouldn't it be better to not have a default argument for `reason` to enforce a unique message (even if it's `"reason unknown (42)"`) being set by the caller?
> 
> Same for `set_fields_escape_state` and `set_not_scalar_replaceable`.

Yeah, that seems better. (didn't want to push that onto others initially). I'll drop the default reason string

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PR: https://git.openjdk.java.net/jdk/pull/7428