[LLVMdev] Memset/memcpy: user control of loop-idiom recognizer

[Hal Finkel]

----- Original Message -----
> From: "Joerg Sonnenberger" <joerg at britannica.bec.de>
> To: llvmdev at cs.uiuc.edu
> Sent: Saturday, December 6, 2014 3:48:32 PM
> Subject: Re: [LLVMdev] Memset/memcpy: user control of loop-idiom recognizer
> 
> On Sat, Dec 06, 2014 at 07:06:31AM -0600, Hal Finkel wrote:
> >  - Direction (should the memory be traversed forward or backward)
> 
> I don't think that this makes sense for memset and memcpy. It does
> matter for memmove.

I was trying to list things that might affect performance. Even for memcpy, the direction can matter for performance, depending on how the hardware prefetcher and other parts of the memory subsystem work.

 -Hal

> 
> Joerg
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory