RFR: 8263775: C2: igv_print() crash unexpectedly when called from debugger [v2]

[Yi Yang]

> When investigating another c2 crash, I found igv_print crashed unexpectedly when called from the debugger. The problem is no matter whether we have created an igv printer in `Compile::igv_print_method_to_file`:
> 
> https://github.com/openjdk/jdk/blob/444a80b920f7cb61b4607d9d245d410bf872b27f/src/hotspot/share/opto/compile.cpp#L4792-L4800
> 
> `Compile:: should_print`(called by `print_method()`) would create a new one, and entering into unexpected network_stream initialization(See hs_err on JBS):
> 
> https://github.com/openjdk/jdk/blob/444a80b920f7cb61b4607d9d245d410bf872b27f/src/hotspot/share/opto/compile.hpp#L628-L638
> 
> For debug purposes, we can skip checking should_print(), printing graph directly. (But even if applying this patch, igv_print can not work well since it seems produces an ill-formed ideal graph whose tags are not enclosed, thus can not be recognized by idealgraphvisualizer, this looks like a related by different fix, so I might create another PR to address this?)
> 
> Thanks!
> Yang

Yi Yang has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  fix igv_print crash

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3065/files
  - new: https://git.openjdk.java.net/jdk/pull/3065/files/09cd043e..056c6557

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3065&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3065&range=00-01

  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3065.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3065/head:pull/3065

PR: https://git.openjdk.java.net/jdk/pull/3065