[Buildroot] Help adding a prerequisite to GCC

[Yann E. MORIN]

Scott, All,

On Saturday 28 July 2012 00:27:23 Scott Moore wrote:
> I'm trying to compile a toolchain with LTO support in gcc.
> I tried to do this by adding the additional gcc flag "--enable-lto", but 
> the build fails (unsurprisingly) because building gcc with lto support 
> requires libelf, which is not currently a prerequisite for gcc in buildroot.
> 
> To fix this, I tried adding libelf to gcc-uclibc-4.x.mk by adding:
> GCC_HOST_PREREQ += host-libelf
> GCC_TARGET_PREREQ += libelf

Please, note that only gcc-4.5 requires libelf for LTO.
gcc-4.6 and above do *not need libelf for LTO (nor any other lib).

So, this PREREQs should be conditional to the gcc version.

Or you can use crostool-NG as a backend, that already has all the magic to
build an LTO-capable toolchain (as well as using GRAPHITE).

Regards,
Yann E. MORIN.

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