[PATCH] D104179: [NFC] [LoopIdiom] [LoopNest] Create LoopIdiomRecognize as a LoopNestPass

[Zheng Qian via Phabricator via llvm-commits]

qianzhen added a comment.

When the loop idiom transformation processes a memset instruction in a loop, currently it only handles the memset with a compile-time constant size. The motivation of this work is to relax this limitation, so that a memset with a variable size in a loop may still be processed and promoted to a larger memset if it passes all the eligibility checks. Performance-wise, promoting the memset in a loop to a larger memset reduces the number of calls to memset; hence reducing the overall call overhead.
A similar technique may also apply to the memcpy with a variable size in a loop.


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https://reviews.llvm.org/D104179