Clang 3.4 Performance Very Strong Against GCC 4.9

[bnolsen]

When I used clang for a project at work a while back (a few million lines, with precompiled headers) I was rather disappointed with the (rather hyped) compilation speed. It's not faster than the other compilers we use. The thing (I think) is I'm compiling with debug symbols (symbols, but optimized or a mixed optimization level in different parts, but always with symbols). It might just be something with that specific project, but when compile time is benchmarked it looks like it is usually without debug symbols. A program is build countless of times by its developers, and we want symbols (for use in debuggers ourself or with crash dumps from testers or users). In my opinion compile times with symbols is more (or at least as) important than without as most users use precompiled programs in most cases anyway, with the exception of gentoo users and when people are applying custom patches.

Releases are made in release mode and code should be run and tested that way, with some files compiled debug as necessary for crash analysis. With any level of threading this is absolutely necessary.

[przemoli]

Not with the latest git, but I am running Mesa 10.0.1 with a git from about two weeks ago and it works fine.

But does it run faster then when compiled with gcc?

[Qaz`]

Releases are made in release mode and code should be run and tested that way, with some files compiled debug as necessary for crash analysis. With any level of threading this is absolutely necessary.

You can build your release config (-O2 and release libraries or whatever that may be) with symbols (-g on clang and gcc), the symbols are not loaded on execution (you can even strip the symbols before sending it somewhere for testing, and still use it when you get crash dumps back).

The exact config and optimization level to use in testing in different phases may vary, but that was not the question here. On top of that, the main thing is for the programmers ow builds, as they are the ones building the project again and again, optimized or not optimized, the symbols are needed.