Among The Changes/Features Coming For GCC 6

[phoronix]

Phoronix: Among The Changes/Features Coming For GCC 6

First and foremost, with the release of GCC 6 the default C++ mode will now be GNU++14/C++14 rather than GNU++98!..

http://www.phoronix.com/scan.php?page=news_item&px=GCC-6-Compiler-Features-1

[Turtleggjp]

So with GCC 6 we have -march=skylake-avx512 for the Skylake Xeon CPUs, but what about the regular desktop CPUs? I don't see -march=skylake listed in the documentation for GCC 5 (last one is -march=broadwell), so I'm guessing the 5.x branch doesn't have it either. Will GCC 6 have support for -march=skylake, or should I just use -march=native on a skylake system?

[octoploid]

Yes, gcc-6 has support for -march=skylake. See: https://gcc.gnu.org/onlinedocs/gcc/x...ml#x86-Options

[nils_]

It would appear Intel didn't add any new instructions to Skylake, AVX-512 will come with Skylake-E.

[carewolf]

It would appear Intel didn't add any new instructions to Skylake, AVX-512 will come with Skylake-E.

Well, I think they readded the transactional memory instructions they have tried a few times already but had to disable because they were broken.

[nils_]

Well, I think they readded the transactional memory instructions they have tried a few times already but had to disable because they were broken.

Yeah, but that's not technically a new instruction. Still an absolute disgrace that this seems to be broken for 3 generations, although it supposedly works on the E7 Series.

[quaz0r]

hopefully defaulting to c++14 will encourage people to start writing modern code. of course, it will likely be another decade before all the binary distros that people use like the debian-based distros will actually start shipping gcc 6.

[discordian]

hopefully defaulting to c++14 will encourage people to start writing modern code. of course, it will likely be another decade before all the binary distros that people use like the debian-based distros will actually start shipping gcc 6.

Dont see why the default flag would affect how people write code, writing modern code is possible since some time. It will however force some old code to be made compilable with c++11.
The issue is though that the library of GCC5 and newer is breaking binary compatibility, getting this all into place is a daunting task (see https://wiki.debian.org/GCC5).

[Zan Lynx]

Dont see why the default flag would affect how people write code, writing modern code is possible since some time. It will however force some old code to be made compilable with c++11.
The issue is though that the library of GCC5 and newer is breaking binary compatibility, getting this all into place is a daunting task (see https://wiki.debian.org/GCC5).

It really shouldn't matter because people should be setting the -std flag to what version they need. A lot of projects don't. Changes like this will make it obvious why they should.