Bump Prebuilt Toolchain

[alonamid]

Related issue: #732

Type of change: bug fix

Impact: other

Release Notes

[davidbiancolin]

LGTM

[davidbiancolin]

This is out-of-scope for this PR, but I'm slightly concerned about having the tars in the main repo as it might lead to considerable bloating. It seems to me using a submodule or an S3 bucket, that we only pull in on running ec2fast would be desirable. Or @a0u, do think these tarsballs are small enough it shouldn't matter

[a0u]

@davidbiancolin: Yeah, git LFS or S3 would be the proper solution, although I don't think the problem is that urgent just yet.
Compared to the old FireSim prebuilt toolchain, there are two measures that improve the efficiency of storing the tarballs in git:

• This repo is shallow-cloned by Chipyard during the install, so the blobs corresponding to the older builds aren't actually fetched:
  

  chipyard/scripts/build-toolchains.sh

  Lines 81 to 83 in cca3cd0

  	module=toolchains/riscv-tools/riscv-gnu-toolchain-prebuilt
  	git config --unset submodule."${module}".update || :
  	git submodule update --init --depth 1 "${module}"

  
  (Note: This means we have to be diligent about tagging commits so they remain reachable by past Chipyard releases.)
• All x86 binaries are also stripped, which saves considerable space.

However, the git history bloat will eventually make it unwieldy to maintain, although at our release cadence (every ~6 months) we still have some headroom.

[davidbiancolin]

Oh, i'm stupid. It's already a submodule. + Shallow clone, opts -- yeah no reason to change this anytime soon. Sorry for the confusion.

[a0u]

@alonamid: Did the riscv-gnu-toolchain commit hash not change? What is different about this version?

[davidbiancolin]

For some reason, the commited tarballs didn't match the hash / checked in sources. When I built an SPEC with the prebuilt toolchain I'd see failures consistent with an old riscv-gcc bug, whereas if i built teh toolchain from scratch they ran cleanly. I checked the submodule pointers and they looked good. So Alon kindly rebuilt the toolchain.

[davidbiancolin]

I think @NathanTP tried running spec2017 recently and had problems. This is probably why.

[a0u]

Ah ok, that was probably my fault somehow.