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tislam (Tarique Islam)
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Apr 16 2020, 5:32 AM (45 w, 5 d)

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Tue, Feb 2

tislam added a comment to D94576: [LoopVectorize] Guard verifyFunction with EXPENSIVE_CHECKS macro.
opt -passes='loop-vectorize' -aa-pipeline=default -o ./tmp.bc D94576_LV_only.ll
Tue, Feb 2, 8:01 AM · Restricted Project

Jan 26 2021

tislam added a comment to D94576: [LoopVectorize] Guard verifyFunction with EXPENSIVE_CHECKS macro.

Thank you for your input. Do you have any suggestion regarding this change? Please let me know if you need additional information from my side.

Jan 26 2021, 6:27 AM · Restricted Project

Jan 14 2021

tislam added reviewers for D94576: [LoopVectorize] Guard verifyFunction with EXPENSIVE_CHECKS macro: fhahn, lebedev.ri.
Jan 14 2021, 4:13 PM · Restricted Project
tislam added a comment to D94576: [LoopVectorize] Guard verifyFunction with EXPENSIVE_CHECKS macro.

Hi @lebedev.ri, I have uploaded an IR file that demonstrates the compile-time implications on vanilla llvm on our system. I used the following invocation.

Jan 14 2021, 6:36 AM · Restricted Project

Jan 13 2021

tislam added a comment to D94576: [LoopVectorize] Guard verifyFunction with EXPENSIVE_CHECKS macro.

So are the compilation time issues reproducible with vanilla llvm, or only in your local branch?
If latter, shouldn't the fix (which isn't hiding the verification under) belong to the branch?

Jan 13 2021, 7:13 AM · Restricted Project
tislam added a comment to D94576: [LoopVectorize] Guard verifyFunction with EXPENSIVE_CHECKS macro.

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.

Jan 13 2021, 6:42 AM · Restricted Project

Jan 12 2021

tislam added a reviewer for D94576: [LoopVectorize] Guard verifyFunction with EXPENSIVE_CHECKS macro: jdoerfert.
Jan 12 2021, 6:54 PM · Restricted Project
tislam added a reviewer for D94576: [LoopVectorize] Guard verifyFunction with EXPENSIVE_CHECKS macro: mkuper.
Jan 12 2021, 6:41 PM · Restricted Project
tislam requested review of D94576: [LoopVectorize] Guard verifyFunction with EXPENSIVE_CHECKS macro.
Jan 12 2021, 6:36 PM · Restricted Project
tislam updated tislam.
Jan 12 2021, 11:30 AM
tislam updated tislam.
Jan 12 2021, 11:19 AM

Dec 1 2020

tislam added inline comments to D91576: [MemCpyOpt] Correctly merge alias scopes during call slot optimization.
Dec 1 2020, 11:19 AM · Restricted Project