RFR: 8240363: Refactor Compile::Output() to its own Phase

[Erik Österlund]

Hi,

The Compile::Output function comes with a lot of baggage (state and 
related functions), that is
mostly unrelated to other parts of a compilation unit. This cluttering 
of unrelated stuff on
Compile makes the code messy.This is a proposal to break out that state 
and embed it into a
separate Phase.

This patch moves ~800 LOC away from Compile. There are more 
opportunities for refactoring further,
but my intention with this patch is to focus on things belonging to 
Output() in particular. I tried
to be as mechanical as possible, and not change logic.

One slight difference in logic is that we used to advance the 
frame_slots before calling Code_Gen(),
and stash away the _orig_pc_slot to the value before it was advanced, 
way before output is called.
In order to have PhaseOutput live only across Output(), I changed this 
to advancing the frame_slots
as usual before Code_Gen(), and during PhaseOutput, I set the 
_orig_pc_slot to the previous frame_slot
(which now points at the sp). That bit of untangling allowed PhaseOutput 
to live only across the Output()
call, followed by code installation (which I moved into Code_Gen, to 
narrow down the life time of
PhaseOutput).

People maintaining non-Oracle platforms might want to have a go at 
compiling this to see if I managed
to catch all code motion in the AD files.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8240363

Webrev:
http://cr.openjdk.java.net/~eosterlund/8240363/webrev.00/

Testing:
hs-tier{1-3}

Thanks,
/Erik