JDK10/RFR(L): 8144448: Avoid placing CTI immediately following or preceding RDPC instruction.
patric.hedlin at oracle.com
Thu Jun 15 16:06:27 UTC 2017
I would like to ask for help to review the following change/update:
*** As a comment to the discussion on how to simplify processing of
this change/update comes with an additional prerequisite (patch)
whitespace and two lingering uses of 'NOT_LP64' and 'LP64_ONLY'.
8144448: Avoid placing CTI immediately following or preceding RDPC
Approach taken here is to handle 'rdpc' in the same manner as
a simple scheme to prohibit the assembler from emitting any 'rdpc'
back-to-back with other CTI ('rdpc' itself included), inserting
'nop' as needed.
This change is applied to all generations of SPARC cores event
though it is the
SPARC Core S5 that is the actual target. Benchmarking on T4 and M7
there is no penalty. This choice (which is subject to change) has
been made in
order to give the update some mileage while waiting for Core S5
hardware to be
available in regular testing.
Mostly tested on JDK9 (jtreg/RBT/hotspot/tier0-comp).
Testing on JDK10 (jtreg/RBT/hotspot/precheckin-comp).
More information about the hotspot-compiler-dev