[llvm-commits] [PATCH/RFC] Loop Data Software Prefetching

[dag at cray.com]

Hal Finkel <hfinkel at anl.gov> writes:

>> After chandler's refactoring to TTI you can now chain
>> multiple TTI analysis one after the other. You can implement your
>> own TTI that will override the default TTI. Much like X86 overrides
>> the basic TTI which overrides NoTTI.
>
> The problem is that this makes experimenting difficult; changing
> anything would require recompiling -- and it makes it impossible for
> the user to override the behavior. If I add the command line flags,
> for example, to PPCTTI, then I'd need to use different flags in
> X86TTI, and connecting all of these flags with clang flags becomes
> messy.
>
> What do you suggest?

What we did here was put basic information in the target attributes
(some of the patch series I sent earlier) and then provided command-line
overrides for experimenting.  That keeps things simple for most people
and allows power users to do some tuning.

I'm going to look at TTI and how our target models could integrate into
that.

                              -David