hg: jdk/hs: 8191915: JCK tests produce incorrect results with C2

[rickard.backman at oracle.com]

Changeset: a81c930a8838
Author:    rbackman
Date:      2018-01-18 19:21 +0100
URL:       http://hg.openjdk.java.net/jdk/hs/rev/a81c930a8838

8191915: JCK tests produce incorrect results with C2
Reviewed-by: thartmann, vlivanov, goetz

! src/hotspot/share/opto/mathexactnode.cpp
! src/hotspot/share/opto/mathexactnode.hpp
+ test/hotspot/gtest/opto/test_mathexact.cpp
+ test/hotspot/jtreg/compiler/intrinsics/mathexact/LongMulOverflowTest.java