[LLVMdev] [llvm-commits] [PATCH] BasicBlock Autovectorization Pass

Sebastian Pop spop at codeaurora.org
Tue Dec 27 10:19:03 PST 2011


On Tue, Dec 20, 2011 at 2:08 PM, Hal Finkel <hfinkel at anl.gov> wrote:
> On Tue, 2011-12-20 at 13:57 -0600, Sebastian Pop wrote:
>> Hi,
>> I see that there are two functions in your code that are O(n^2) in
>> number of instructions of the program: getCandidatePairs and
>> buildDepMap.  I think that you could make these two functions faster
>> if you work on some form of factored def-use chains for memory, like
>> the VUSE/VDEFs of GCC.
> Thanks for the comment! I am not aware of anything along these lines,
> although it would be quite helpful. The pass spends a significant amount
> of time running the aliasing-analysis queries.

I see no reason against committing the vectorizer pass as it is now:
we can rework the slow parts of the vectorizer once we'll have the
factored use-def chains for memory.

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