mzolotukhin added a comment. Hi,
I've been monitoring compile-time for quite a while, so let my put my 2 cents here too. > Who is the audience for this information? > What information do they want from a time report? > How do we present that information in a way that's not misleading (given > Clang's architecture)? I would find the timers extremely useful. Even if they overlap, they still would 1) be a good indicator of a newly introduced problem and 2) give a rough idea where frontend time is spent. I agree that it wouldn't be super-accurate, but the numbers we usually operate are quite high (e.g. <some part> started to take 1.5x time). When we decide to investigate it deeper, we can use more accurate tools, such as profilers. All that said, if we can make timers more accurate/not-overlapping, that surely would be helpful as well. > Can we deliver useful value compared to a modern, dedicated profiling tool? Having timers, especially producing results in the same format, as existing LLVM timers, would be much more convenient than using profilers. With timers I can simply add a compile-time flag to my test-suite run and get all the numbers in the end of my usual run. With profilers it's a bit more complicated. Speaking of timers overlapping and mutual calling: LLVM timers also have this problem, and e.g. if there is problem is in some analysis (say, ScalarEvolution), we see indications in several other passes using this analysis (say, IndVarSimplify and LoopStrengthReduction). While it does not immediately show the problematic spot, it gives you pretty strong hints to where to look at first. So, having even not-perfect timers is still useful. Also, I apologize for LGTMing the patch earlier while it was not properly reviewed - I didn't notice it didn't have cfe-commits in subscribers, and it had been waiting for a review for quite some time (so I assumed that all interested parties had their chance to look at it). Thanks, Michael https://reviews.llvm.org/D43578 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
