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

[Adam Nemet via llvm-dev]

> 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 <mailto: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).

That is why I think bringing llc into the discussion was confusing, at least I think it confused Renato.  My whole point was that you can write target-independent tests with *opt* but not with llc of course (which I think was Renato’s conclusion).

Adam

> 
> -- Matt

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