[llvm-dev] Loop Vectorize: Testing cost model driven transformations

[Michael Kuperstein via llvm-dev]

Oh, ok, so the difference in practice is which triple llc and opt default
to - llc defaults to LLVM_DEFAULT_TARGET_TRIPLE, and opt defaults to "".

I never realized that - I thought opt also defaults to the, well, default.
Thanks!

On Fri, Dec 2, 2016 at 11:12 AM, Adam Nemet <anemet at apple.com> wrote:

>
> On Dec 2, 2016, at 11:06 AM, Matthew Simpson <mssimpso at codeaurora.org>
> wrote:
>
>
> On Fri, Dec 2, 2016 at 1:30 PM, Michael Kuperstein via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> It isn't relevant, really, Matt just brought up "llc --version" as a way
>> to show the default triple and native cpu.
>> The same question ("Which TTI do/should we get with -mcpu=generic / when
>> not providing -mcpu at all") applies to opt.
>>
>
> And just to be clear in case there was any confusion, in opt when a target
> is not specified we get the generic TTI, not one for the host or default
> triple indicated by llc. I think this was Adam's original point/question.
> As long as the tests we want to remain target-independent don't specify a
> target triple, we should get the same generic TTI on any host.
>
>
> Yes opt an llc are completely different in this regard.  llc always needs
> a target to generate code for.  opt does not, it uses data layout and TTI
> (the default if not target is specified).
>
>
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