search for: foldphiargloadintophi

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2020 May 05
2
Missing vectorization of loop due to load late in the loop
...e returns false. If we just move the load before the definition of %0 in the vectorizer input, then we instead get LV: We can vectorize this loop! Originally the loop had two loads, and then one of them was actually placed early in the loop block. That was done by instcombine, by InstCombiner::FoldPHIArgLoadIntoPHI. The reason this doesn't happen for the load we see in the reduced example is because after loop rotation licm hoists the start value of the PHI, so when instcombine tries to do FoldPHIArgLoadIntoPHI, the start value isn't placed in the direct predecessor block of the PHI, and the folding...