[8u20] RFR(M): 8031752: Failed speculative optimization should be reattempted when root of compilation is different

[Roland Westrelin]

Please, review backport to 8u20. The patch applies cleanly. It’s been in jdk9 for more than 2 weeks. 8032633 that enabled type speculation and stresses this change was pushed a week ago.

http://cr.openjdk.java.net/~roland/8031752/webrev.03/
https://bugs.openjdk.java.net/browse/JDK-8031752
http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/fdad2932c73f

Roland.