[PATCH] D73534: [DebugInfo] Enable the debug entry values feature by default

Thu Jan 30 12:47:21 PST 2020

vsk added a comment.

In D73534#1849382 <https://reviews.llvm.org/D73534#1849382>, @djtodoro wrote:

> @vsk Thanks a lot for sharing this!
>
> > (however the machine was not stabilized for perf measurements)
>
> What can be the reason of that?

Stabilization entails removing variables from the system that can affect performance. This usually entails killing extraneous background processes and disabling cpu frequency scaling. This can make the system hard to use (e.g. our stabilization script kills the bluetooth daemon, which I need to type).

I have some numbers for stage2 clang builds on macOS:

| Config                            | dSYM Size (bytes) | Aggregate DWARF size in .o's (bytes) [1] | # of call site entries | # of call site parameters |
| Stage2 RelWithDebInfo             | 1682677554                 | 8058178927                                        | 5777959                      | 0                         |
| Stage2 RelWithDebInfo + entryvals | 1691586966                 | 8069013985                                        | 5777959                      | 584620                    |
|

Something seems strange to me about this result. It looks a bit like the average number of arguments at call sites in clang is 0.1. Has anyone else seen this result? I'll keep poking.

[1] Just summing the size of all 'DWARF' sections in all .o's in the build directory, as before.

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  https://reviews.llvm.org/D73534/new/

https://reviews.llvm.org/D73534