hg: panama/dev: C2: Improve diagnosability

[vladimir.x.ivanov at oracle.com]

Changeset: 0c79d6e11228
Author:    vlivanov
Date:      2018-03-07 00:10 +0300
URL:       http://hg.openjdk.java.net/panama/dev/rev/0c79d6e11228

C2: Improve diagnosability

! src/hotspot/share/opto/c2_globals.hpp
! src/hotspot/share/opto/compile.cpp
! src/hotspot/share/opto/phasetype.hpp