Monday, May 2. 2005
The joys of auto-vectorization
Well, not really, as I'm finding out.
With the release of Mac OS X Tiger last Friday, I finally got a chance to play around with gcc 4.0 and its auto-vectorization feature. A few, simple contrived cases convinced me that the feature actually worked, but I was quite disappointed when I began compiling my own C projects with the appropriate flags turned on.
I have yet to find a single loop that successfully auto-vectorized. (FYI, I'm using the -fdump-tree-vect-stats option which dumps the output of vectorization phase to a separate file.)
I guess moving forward, I should start coding with auto-vectorization in mind... which will be challenging considering the strict requirements (just look at the examples on that page!)
Anyway, I thought I was being clever last night when I built Emacs.app with -ftree-vectorize.
Now I doubt whether even a single loop was vectorized.
Oh well, it's a start. I wonder if auto-vectorization will ever get to the point where hand-coding vector instructions is no longer necessary for 90% of code...? (Kind of like what C did to writing in assembly language, I guess.)
With the release of Mac OS X Tiger last Friday, I finally got a chance to play around with gcc 4.0 and its auto-vectorization feature. A few, simple contrived cases convinced me that the feature actually worked, but I was quite disappointed when I began compiling my own C projects with the appropriate flags turned on.
I have yet to find a single loop that successfully auto-vectorized. (FYI, I'm using the -fdump-tree-vect-stats option which dumps the output of vectorization phase to a separate file.)I guess moving forward, I should start coding with auto-vectorization in mind... which will be challenging considering the strict requirements (just look at the examples on that page!)
Anyway, I thought I was being clever last night when I built Emacs.app with -ftree-vectorize.
Now I doubt whether even a single loop was vectorized.Oh well, it's a start. I wonder if auto-vectorization will ever get to the point where hand-coding vector instructions is no longer necessary for 90% of code...? (Kind of like what C did to writing in assembly language, I guess.)
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