[cfe-dev] How clang from packages is build?

[Hans Wennborg via cfe-dev]

On Thu, Sep 22, 2016 at 12:51 AM, Sylvestre Ledru via cfe-dev
<cfe-dev at lists.llvm.org> wrote:
> Le 22/09/2016 à 03:33, Mehdi Amini a écrit :
>> Hi,
>>
>> I was wondering the same thing recently and Hans pointed me to llvm/utils/release.
>>
>> It turns out we’re not using LTO :(
>> (Neither PGO…)
> In the Debian/Ubuntu packages (and this is general to packaging), we are:
> * relying on the build system of the application itself
> * adding some flags like "-g -O2" and the fortify options https://wiki.debian.org/Hardening
>
> For the linker, for the LLVM toolchain, it depends if the version of binutils in the distro has it or not (at least 2.23.1-1~exp3).
> Here, for the Debian & Ubuntu packages, I am using binutils gold but not sure the LTO option is set to the llvm build system?!
>
> However, happy to try that (I think this should be part of the build system, at least for LTO).

I think that's what the -LLVM_ENABLE_LTO={Full,Thin} option is for,
but it's not enabled by default.

Cheers,
Hans