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Re: [patch] jump threading multiple paths that start from the same BB
On 07/09/2018 01:19 AM, Aldy Hernandez wrote:
>>
>> I'd like decisions about how to expand branches deferred until rtl
>> expansion. Kai was poking at this in the past but never really got any
>> traction.
>
> For the record, the problem in this testcase is that switch lowering is
> riddled with back end specific knowledge (GET_MODE_SIZE uses as well as
> some rtx cost hacks).
Yea. Switch lowering is going to have some of these as well, though I
think BRANCH_COST is more pervasive.
>
>>
>> Many tests should turn into gimple IL tests.
>
> Yeah, though for tests like the threading ones, they're already
> sufficiently convoluted that turning them into gimple IL tests will make
> them even harder to read. Oh well, I guess?
It might make them harder to read, but it would guarantee consistent
gimple fed into the optimizer across our targets which in turn ought to
result in consistent behavior by the optimizer which in turn should
simplify the test and make them more consistent over time.
Jeff