RFR(L): 8003854: PPC64 (part 115): Introduce lateExpand that expands nodes after register allocation.
goetz.lindenmaier at sap.com
Fri Oct 4 10:48:13 PDT 2013
thanks for assigning that to me. Can/may I change the title
of the bug? I would like to put in the 'PPC (part 115)' marker.
Have fun reviewing ;)
From: Christian Thalinger [mailto:christian.thalinger at oracle.com]
Sent: Friday, October 04, 2013 12:02 AM
To: Lindenmaier, Goetz
Cc: hotspot-dev at openjdk.java.net; ppc-aix-port-dev at openjdk.java.net; Vladimir Kozlov
Subject: Re: RFR(L): 8003854: PPC64 (part 115): Introduce lateExpand that expands nodes after register allocation.
Before I start to review this I've assigned the bug to you, Goetz:
On Oct 2, 2013, at 6:49 AM, "Lindenmaier, Goetz" <goetz.lindenmaier at sap.com> wrote:
> we extended C2 by what we call lateExpand. LateExpand expands nodes
> after register allocation.
> Some nodes can not be expanded during matching. E.g., register
> allocation might not be able to deal with the resulting pattern. To
> allow better scheduling in such cases, we introduce lateExpand which
> runs after register allocation. Whether and how nodes are expanded is
> specified in the ad-file. See block.cpp for a detailed
> documentation. We use this for some nodes on ppc, and extensively on
> For an example, see the webrev.
> We added some utility functions in node.hpp and block.hpp used by
> PhaseCFG::LateExpand() or the Node::lateExpand functions. Also,
> MachConstantBaseNode gets the two new functions, as we need to
> late expand it.
> To skip the walk over the IR if no lateExpand is needed, we use
> Matcher::require_late_expand set in the ad file. This ends up in
> ad_<cpu>.cpp, thus can not be evaluated by the C++ compiler. If you
> agree, I would use a "const bool EnableLateExpand" in
> globalDefinitions_<cpu>.hpp. (There is no suitable c2_<xxx>_<cpu>.hpp
> We allready mailed a webrev with this change after last year's
> JavaOne, but there was no discussion on it.
> Again, this change is 'L', but the code is not used on other
> platforms than PPC64 (so far). So the impact on those platforms
> should be minimal.
> Please review and test this change.
> Thanks and best regards,
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