Upgrade to use GCC 10.x toolchain

[tcal-x]

@danc86 saw a significant performance improvement when using GCC 10.x toolchain. We can update the docs to point to the newer version of the toolchain.

[JosephBushagour]

Link to relevant discussion with numbers here: https://github.com/google/CFU-Playground/pull/172#discussion_r672673739

[akioolin]

Hi :

I got a problem after update to gcc 10.2.0 from sifive release.

In this release, it seems have no prebuild libstdc++.a for rv32im, which the march setting in CFU-Playground.

Could any one kindly to tell me which version could be used or change march setting to which architecture?

Many thanks.

BR, Akio

[danc86]

avg noticed this issue with the Sifive prebuilt 10.2 toolchain. He observed that the 10.1 release still had rv32im, so we could use that in the short term.

[akioolin]

Hi, @danc86 :

Many thanks. downloading 10.1.0.

BR, Akio

[mithro]

We should probably move to our own custom built toolchains in conda -> https://github.com/hdl/conda-compilers

[tcal-x]

I've been experimenting with make-env (Conda) in CFU Playground, and currently the only issue is finding a Conda package for the GCC RISC-V toolchain that includes g++. I've opened https://github.com/hdl/conda-compilers/issues/25 to request a package for GCC v10.1 including g++.

[mithro]

I've opened hdl/conda-compilers#25 to request a package for GCC v10.1 including g++.

This is something we should be able to do ASAP. @PiotrZierhoffer - Who should look into this?

[PiotrZierhoffer]

I created https://github.com/hdl/conda-compilers/pull/26 to kick this off