[LLVMdev] How to unroll reduction loop with caching accumulator on register?

[Dmitry Mikushin]

Dear all,

Attached notunrolled.ll is a module containing reduction kernel. What I'm
trying to do is to unroll it in such way, that partial reduction on
unrolled iterations would be performed on register, and then stored to
memory only once. Currently llvm's unroller together with all standard
optimizations produce code, which stores value to memory after every
unrolled iteration, which is much less efficient. Do you have an idea which
combination of opt passes may help to cache unrolled loop stores on a
register?

Many thanks,
- D.
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