Displaying 4 results from an estimated 4 matches for "x86unpckl".
2011 Mar 16
3
[LLVMdev] Long-Term ISel Design
All,
As I've done more integrating of AVX work upstream and more tuning here,
I've run across several things which are clunky in the current isel
design. A couple examples I can remember offhand:
1. We have special target-specific operators for certain shuffles in X86,
such as X86unpckl. I don't completely understand why but Bruno
indicated it was to address inefficiecies. One of those is the need
to check masks multiple times (once at legalize and again at isel).
2. Sometimes DAGs are legal in some contexts but not others and it is a
pain to deal with. A good exa...
2011 Mar 17
0
[LLVMdev] Long-Term ISel Design
...e done more integrating of AVX work upstream and more tuning here,
> I've run across several things which are clunky in the current isel
> design. A couple examples I can remember offhand:
>
> 1. We have special target-specific operators for certain shuffles in X86,
> such as X86unpckl. I don't completely understand why but Bruno
> indicated it was to address inefficiecies. One of those is the need
> to check masks multiple times (once at legalize and again at isel).
It also eliminates a lot of fragility. Before doing this, X86 legalize would have to be very car...
2011 Mar 17
2
[LLVMdev] Long-Term ISel Design
Chris Lattner <clattner at apple.com> writes:
>> 1. We have special target-specific operators for certain shuffles in X86,
>> such as X86unpckl.
> It also eliminates a lot of fragility. Before doing this, X86
> legalize would have to be very careful to specifically form shuffles
> that it knew isel would turn into (e.g.) unpck operations. Now
> instead of forming specific carefully constructed shuffle masks (not
> making...
2011 Mar 18
0
[LLVMdev] Long-Term ISel Design
On Mar 17, 2011, at 9:32 AM, David A. Greene wrote:
> Chris Lattner <clattner at apple.com> writes:
>>> 1. We have special target-specific operators for certain shuffles in X86,
>>> such as X86unpckl.
>
>> It also eliminates a lot of fragility. Before doing this, X86
>> legalize would have to be very careful to specifically form shuffles
>> that it knew isel would turn into (e.g.) unpck operations. Now
>> instead of forming specific carefully constructed shuffle ma...