[PATCH] D94576: [LoopVectorize] Guard verifyFunction with EXPENSIVE_CHECKS macro

Wed Jan 13 02:00:14 PST 2021

fhahn added a comment.

> We have found that the calls to verifyFunction can take up to 66% of the time spent in llvm::LoopVectorizePass::processLoop. For some source files, verifyFunction took around 10% of the total compile time.

See also https://bugs.llvm.org/show_bug.cgi?id=47712. I'm curious, where is the time spent in the verifier? PR47712 mentions a regression in the verifier where the majority of time is spent in `visitMDNode`. Is this a similar issue?

In general, I think the function verification has been very valuable in terms of surfacing bugs and I would be very reluctant to move it behind expensive checks, especially since we had this check for a long time. As mentioned in PR47712, I think `verifyFunction` should be `O(# instructions in function)` and not behind `EXPENSIVE_CHECKS`.

Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D94576