[LLVMdev] Trying out Loop Vectorizer

[Hal Finkel]

----- Original Message -----
> From: "Nadav Rotem" <nrotem at apple.com>
> To: "Benjamin Kramer" <benny.kra at gmail.com>
> Cc: "llvmdev at cs.uiuc.edu List" <llvmdev at cs.uiuc.edu>
> Sent: Monday, December 31, 2012 5:26:18 PM
> Subject: Re: [LLVMdev] Trying out Loop Vectorizer
> 
> 
> 
> 
> 
> On Dec 31, 2012, at 11:57 AM, Benjamin Kramer < benny.kra at gmail.com >
> wrote:
> 
> 
> I'm not entirely sure why this is the case, the target specific stuff
> for opt is still very new, but at the moment you have to explicitly
> set a triple for opt so it can access target-specific bits to
> estimate the cost of vectorization.
> 
> I think that this is a good opportunity to discuss this topic. At the
> moment 'opt' does not use the triple that is found in the module in
> order to initialize the backend and the backend related analysis
> passes. It relies on the '-mtriple' command line flag. LLC on the
> other hand uses the host triple. I see the following options:
> 
> 
> 1. 'opt' does not initialize the backend passes unless '-mtriple' is
> used. (the current option)
> 2. 'opt' grabs the triple from the bit code file and uses it to
> initialize the backend passes.
> 3. 'opt' gets the default target triple (like llc).
> 
> 
> I think that Nick said that he prefers #2.

As do I.

 -Hal

> 
> 
> Nadav
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-- 
Hal Finkel
Postdoctoral Appointee
Leadership Computing Facility
Argonne National Laboratory