[llvm-dev] TableGen -time-regions option

[Daniel Sanders via llvm-dev]

Hi Paul,

I'm rather late to the thread but I added the existing -time-regions option when I was debugging a particularly nasty perf problem in TableGen. I really only use it when we have a perf problem downstream.

The main thing I was getting out of it was the ability to annotate periods of time in Xcode Instruments just by adding a NamedRegionTimer to the right function/block (see https://reviews.llvm.org/rGe1414d176048c1f24fc3f54bb923fb48a2b985a3). That helped me track down the work that was taking the time and let me filter out the noise from elsewhere so I could look at the relevant memory allocations+churn. Feel free to change it but I'd like to keep that Instruments integration if we can as I'm sure we'll hit another perf problem sooner or later.

> On 25 Oct 2020, at 17:08, Paul C. Anagnostopoulos via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> I'm pondering a new timing feature for TableGen and am wondering whether anyone uses the existing -time-regions option. Some instrumentation for it appears in CodeGenTarget.cpp and GICombinerEmitter.cpp but nowhere else. If no one is using it, I'll be tempted to remove it.
> 
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