Investigate lower-subreg

Registered by Ramana Radhakrishnan on 2012-05-02

Lower subreg has changed upstream to have a new costs based mechanism to determine when it's not worth splitting some larger types into smaller word type operations. However this has a dependence on the costs in the ARM backend and they would need to be carefully audited along with the way in which this new algorithm behaves. There are a couple of cases where this helps especially with the fix for PR48941 in upstream bugzilla but it makes things worse for some other code sequences involving other modes of copies. This looks like a meaty chunk of work that could do with some more investigation

Blueprint information

Status:
Not started
Approver:
Michael Hope
Priority:
Medium
Drafter:
Ramana Radhakrishnan
Direction:
Needs approval
Assignee:
None
Definition:
Discussion
Series goal:
Accepted for 4.7
Implementation:
Informational Informational
Milestone target:
milestone icon backlog

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[2013-05-28 matthew-gretton-dann] Moved to http://cards.linaro.org/browse/TCWG-131

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