Remove the benchmark

@terrelln No one has responded to http://lists.llvm.org/pipermail/llvm-dev/2019-October/136337.html yet. I think we can just commit the code change for now. Do you need help for committing the patch?

Use triple x86_64 in tests.

@smeenai yeah I will

Fix comments

Merged into D69294

• Merge D69293 into this diff.
• Fix all comments.

Can you try posix_fallocate(fd, 0, len) and see how it performs under memory pressure with btrfs+compression?

I also agree with this. I think llvm/benchmarks would be fine for now either way, but with more benchmarks (which hopefully would be there at some point, I had plans of adding some for a while now but I'm not sure when I'll get to that) subdirectories make sense.

I'll update the description to answer questions, and make the requested changes. I've also answered questions inline below.

Maybe this should be merged with https://reviews.llvm.org/D69294. Since we are moving to a single repository that contains both llvm and lld, we no longer have to split a commit at svn repo boundaries. Since this flag will be used only by lld at least for a while, it feels more natural to commit this and the other one as a single commit.

If you really want to make this fast, I think Intel processors have special-purpose instructions to accelerate SHA1 computation. Have you consider using them?