On 2018-06-15 11:31 +0200, U.Mutlu wrote:
> I tried to use -flto in CXXFLAGS_FOR_TARGET. It successfully built the compilers,
> but later when trying to use the compilers, the linker reported an error about
> something missing and aborted the linking.
PR 48200 renders shared libraries with versioned symbols (".symver") unusable if it
was built with -flto. libstdc++ is affected.
> Of course the rationale was to optimize the compiler itself.
>
> So, the question is: does it not make any sense to use -flto for the build itself?
> (Or should one specify -flto in some of the other config variables like
> CXXFLAGS_FOR_BUILD and/or the ...FLAGS vars maybe?)
Use --with-build-config=bootstrap-lto.
"C(XX)FLAGS_FOR_BUILD=-flto" also makes sense (see PR 59893). But you should use
--disable-shared and build the shared libraries w/o LTO, at least for now to
workaround PR 48200. And you should use patch to workaround PR 60160.
--
Xi Ruoyao <ryxi@xxxxxxxxxxxxxxxxx>
School of Aerospace Science and Technology, Xidian University
