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Re: Unnesting of nested subreg expressions
Björn Haase wrote:
So far, I now think that the solution of the issue would be to extend
gen_lowpart and gen_highpart so that they are able to handle also subreg
inputs and use them at all places that emmit RTL (i.e. expand and split).
Question is whether I should try to simultaneously implement support for the
case of paradoxial subregs as input operand, once I am working on the code?
You were never very clear about what was wrong with gen_highpart and
gen_lowpart with respect to subregs. rtl examples are always helpful,
e.g. showing RTL input and RTL output and pointing out what is wrong.
gen_lowpart already has support for subreg input and presumably should work.
gen_lowpart is already pretty involved. If you need something other
than a trivial fix, it might be better to try to solve the problem in
your md file.
I would suggest only trying to fix things that you have testcases for.
So if you don't have a paradoxical subreg testcase, then don't try to
fix it. You might accidentally make things worse than they already are.
--
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com