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Re: What happened to the IRA interprocedural reg-alloc work? (function_used_regs and friends)
Steven Bosscher <email@example.com> writes:
> I suppose it's theoretically possible to make a good initial guess of
> what registers might be not-clobbered by a function even if the ABI
> says so. For instance, perhaps it's possible to assume that a function
> that doesn't touch any variables in a floating point mode also doesn't
> use/clobber any floating point registers. This assumption could be
> propagated via LTO/WHOPR. If the function turns out to clobber
> registers that were assumed to be untouched, you could just save and
> restore them in the function ("callee saved" so to speak). But I don't
> know how useful that would be.
There was a discussion on this some time ago. The conclusion was that
the partition should help: if the partitions works right the callers and
callees that are commonly should be commonly in the same partition, and
those need RA between themselves. Between partitions you couldn't do RA.
firstname.lastname@example.org -- Speaking for myself only