[LLVMdev] Contributing the Apple ARM64 compiler backend

[Chad Rosier]

Eric,
Feel free to file PRs and CC me on them! :)

 Chad

-----Original Message-----
From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of Manjunath N
Sent: Tuesday, June 24, 2014 5:45 AM
To: llvmdev at cs.uiuc.edu
Subject: Re: [LLVMdev] Contributing the Apple ARM64 compiler backend



Eric Christopher <echristo <at> gmail.com> writes:

> 
> > The big pain issues I see merging from ARM64 to AArch64 are:
> > 1.      Apple have created a fairly complete scheduling model already 
for
> > ARM64, and we'd have to merge the partial? model in AArch64 and theirs. 
We
> > risk regressing performance on Apple's targets here, and we can't
determine
> > ourselves whether we have or not. This is not ideal.
> > 2.      Porting over the DAG-to-DAG optimizations and any other
> > optimizations that rely on the tablegen layout will be very tricky.
> > 3.      The conditional compare pass is fairly comprehensive - we'd have

to
> > port that over or rewrite it and that would be a lot of work.
> > 4.      A very quick analysis last night indicated that ARM64 has
> > implemented just under half of the optimizations we discovered
opportunities
> > for in SPEC and EEMBC. That's a fairly comprehensive number of 
> > optimizations, and they won't all be easy to port.
Eric,
You mention that there a quite a few  optimization opportunities in SPEC
2000/ EEMBC.
I am looking to optimize the Aarch64 backend. Could you please let me know
the big optimizations possible?



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