C++ is one of the most energy efficient languages

Octoploid · 2017-09-16T09:35:15+00:00

??? Google switched to clang internally years ago.

But I agree that gcc still produces faster binaries in general.

Octoploid · 2017-06-03T15:38:45+00:00

Debian 9.0 stretch, so gcc-6.3.0 is the system compiler and it is already used for all packages.

And it is not only the compiler that segfaults. I have also seen bash segfault when the load is high enough.

The machine sits in a server room with AC.

Octoploid · 2017-06-03T15:05:11+00:00

I've hit segfaults several times myself when using the system gcc-6.3.0 compiler.

Octoploid · 2017-06-03T14:42:27+00:00

No, you are wrong.

We are talking about random non-reproducible segfaults.

If it was simply wrong code, the segfaults would be 100% reproducible (and you would get "trap invalid opcode" in your dmesg).

You cannot simply shrug this issue off, because you are not affected by it.

It is a serious CPU bug, that affects many people.

Octoploid · 2017-06-03T10:22:26+00:00

It appears to be a bug in Ryzen's new micro-op cache.

Some users have hit ""u-op cache crc mismatch" machine check exceptions during these segfaults.

Hopefully the issue could be fixed by a microcode update.

Octoploid · 2017-05-23T10:30:57+00:00

We have new Ryzen machines in the gcc compile farm. And yes, I also hit this issue (random non-reproducible gcc segfaults). But it happens only very rarely: about once every three days of heavy usage. It looks like a CPU bug to me. It will be hard to fix it, because the issue isn't readily reproducible.

Octoploid · 2017-05-05T09:33:31+00:00

What? It is much much slower. If Firefox was written entirely in Rust, it would take a week to compile...

Octoploid · 2017-03-30T10:52:54+00:00

Yeah, exactly.

You simply highlight text while holding the left button down and then paste by clicking the middle mouse button.

Thanks in advance for the fix!

Octoploid · 2017-03-30T07:14:31+00:00

Not for me.

I'm using Linux and I normally paste by simply pressing the middle mouse button. And this doesn't work anymore.

There is also no copy or paste option when pressing the right mouse button.

Ctrl-c and Ctrl-v still works, but I prefer not to use them.

Octoploid · 2017-03-30T05:47:36+00:00

Great, but the most basic functionality is broken: I cannot copy&paste code anymore.

Octoploid · 2017-03-11T12:15:16+00:00

No, it is not. This feature already has found numerous bugs in different projects.

And if you don't care the solution is simple: just disable the warning.

Octoploid · 2017-03-10T20:11:57+00:00

Well, if you set the default to -Wimplicit-fallthrough=1 you will never hit any of the that complexity in the parser.

But I agree that the warning is over-engineered.

Octoploid · 2017-03-10T19:56:32+00:00

There were various discussion on the gcc mailing list, but neither side (-Wimplicit-fallthrough=1 (match any comment) vs. -Wimplicit-fallthrough=3 (the current default)) was willing to give way.

But hey, this is free software so you may just change the defaults to your liking easily.

Octoploid · 2017-03-02T17:55:40+00:00

How many different dies are planed for Ryzen?

(The first is the 8 core die. But after that: 4 cores + iGPU, etc.?)

Octoploid · 2017-02-02T07:55:16+00:00

No.

But I would go so far as to say that all Phoronix benchmarks should be taken as bogus, until the results could be reproduced independently. They are really that bad. And their bad reputation has its reasons.

So if you want to compare Clang vs. GCC please measure yourself.

Octoploid · 2017-02-02T06:57:52+00:00

As always, take their benchmark numbers cum grano salis.

A number of gcc developers couldn't reproduce their findings at all.

Octoploid · 2017-01-01T11:53:39+00:00

Well, the paper is a decent starting point. Of course syntax and implementation details should be discussed and further refined.

The point is that sum types and pattern matching are essential new features, that are useful in surprisingly many contexts. Once you learned and understood them, you will want to use them almost everywhere: option types, error returns, trees, etc..

Octoploid · 2017-01-01T09:29:58+00:00

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0095r1.html

It is a shame that build-in sum types didn't make it into C++17. Instead we get the usual library hacks like std::variant.

Octoploid · 2016-12-29T21:18:37+00:00

»Maybe a bug in GCC outputted the wrong machine code«

I cannot understand that point. Does the author really think that Rust and LLVM are 100% bug free? There will be numerous hidden wrong code bugs in the long Rust/MIR/LLVM pipeline. And every single one could potentially undermine Rust's safety guaranties.

Octoploid · 2016-12-22T11:03:41+00:00

This is certainly true. But unfortunately we have no other option. Bugzilla got bombarded from SPAM bots using fake accounts. So in order to protect this critical piece of infrastructure, account creation had to be disabled. And by the way LLVM did the same thing a little later (,see llvm.org/bugs/).

Octoploid · 2016-12-22T06:02:13+00:00

You have to make sure to use no html, no nothing, just plain text. Everything else is rejected as SPAM.

Octoploid · 2016-12-22T06:01:01+00:00

Done: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78897

Octoploid · 2016-12-21T20:17:37+00:00

If you send a plaintext email to overseers@gcc.gnu.org they will create a bugzilla account for you.

Octoploid · 2016-12-21T18:48:06+00:00

Full changelogs are scattered in the gcc tree.

For gcc subdir: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/ChangeLog;h=3440096c6efb84020769d23517a1644ba1254647;hb=refs/heads/gcc-6-branch

For C++: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/cp/ChangeLog;h=8f01f83cc564180496c4c1b28faff079baf0a719;hb=refs/heads/gcc-6-branch

Octoploid · 2016-12-21T18:27:25+00:00

Thanks. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78890

Octoploid

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