linux currently uses clang by default (+ revert instructions)

[Nico Weber]

Hi,

r282246 switched OS=linux builds (i.e. desktop chrome/linux, and desktop chrome/linux with chromeos=1, but NOT chrome/android or "real" chrome/chromeos builds) to use clang as its compiler by default. You can explicitly set clang=0 in your gyp defines if you don't want this. For now, this is very likely temporary to collect some performance data and to find problems, but it'll very likely be permanent at some point. I'll have more to say about the switch when that happens.

For now: The waterfall looks decent as far as I can tell. r282261 contains updated sizes expectations and updates shared library expectations for Google Chrome Linux, so that and the two Linux clobber bots will hopefully cycle green. The memory.fyi waterfall cycles slowly, so I don't know about the state of that yet.

If you see something that's broken, please leave a comment on http://crbug.com/360311 If you must, the change is safe to revert (you need to revert r282261 too, to update expectations). But if just a handful tests fail on just 32bit bots, consider just leaving a comment on the bug and leave me some time to look thursday morning.

Thanks,

Nico

[Steven Bennetts]

Note: this broke goma for derat@ and I (which can lock up your workstation).

Setting clang=0 in my GYP_DEFINES does not fix that either. Dan has goma working again, we will post further updates on http://crbug.com/360311.

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[Nico Weber]

On Thu, Jul 10, 2014 at 9:53 AM, Steven Bennetts <stev...@google.com> wrote:

Note: this broke goma for derat@ and I (which can lock up your workstation).

I just debugged this with derat@ over chat, it sounded like user error to me. To use goma, set use_goma=1 and do nothing else (as in the documentation).

[Steven Bennetts]

Yes, I had the same problem. Apparently we both missed the PSA that 'use_goma=1' in GYP_DEFINES was now the official way to use goma. I guess that counts as "user error" :) 

Here is a convenient link to the documentation for anyone else who set up goma a long time ago and needs to update their configuration.

[Paweł Hajdan, Jr.]

Curious, will gcc-based build continue to be supported on desktop Linux? If not, will patches be accepted to keep it working?

Paweł

[Nico Weber]

On Tue, Jul 22, 2014 at 3:40 AM, Paweł Hajdan, Jr. <phajd...@chromium.org> wrote:

Curious, will gcc-based build continue to be supported on desktop Linux? If not, will patches be accepted to keep it working?

What do you mean with "supported"? See https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/2RzwrIxnvqM – we're going to require gcc 4.8+ (which is what's currently used on Android and Chrome OS, so there's bot coverage for some parts of the code. There very likely won't be a gcc bot for desktop linux (http://crbug.com/395935), but we'll accept patches.

[Paweł Hajdan, Jr.]

On Tue, Jul 22, 2014 at 3:59 PM, Nico Weber <tha...@chromium.org> wrote:

On Tue, Jul 22, 2014 at 3:40 AM, Paweł Hajdan, Jr. <phajd...@chromium.org> wrote:

Curious, will gcc-based build continue to be supported on desktop Linux? If not, will patches be accepted to keep it working?

What do you mean with "supported"? See https://groups.google.com/a/chromium.org/forum/#!topic/chromium-dev/2RzwrIxnvqM – we're going to require gcc 4.8+ (which is what's currently used on Android and Chrome OS, so there's bot coverage for some parts of the code. There very likely won't be a gcc bot for desktop linux (http://crbug.com/395935), but we'll accept patches.

Sounds good, thanks!

Paweł

[Jakob Kummerow]

build/gdb-add-index appears to be broken by this. To be specific:

$ ninja -C out/Debug chrome

$ build/gdb-add-index out/Debug/chrome

$ out/Debug/chrome --no-sandbox --renderer-cmd-prefix="xterm -e gdb -ex run -ex quit -args" some_page.html

# ... hit a DCHECK or something

(gdb) bt

#0  0x0000000000000000 in ?? ()

#1  0x00007f227b49cc3d in v8::base::OS::Abort() () from /usr/local/google/home/jkummerow/chrome/src/out/Debug/lib/libv8.so

../../gdb-7.7.x/gdb/dwarf2read.c:4048: internal-error: dw2_find_pc_sect_symtab: Assertion `result != NULL' failed.

A problem internal to GDB has been detected,

further debugging may prove unreliable.

Quit this debugging session? (y or n)

Saying "n" and hoping for the best turns out to be less than fruitful: the same message will repeat for any other GDB command. When I skip the gdb-add-index step, debugging works as expected. My GDB is the gPrecise default, 7.7-gg7.

While trying to figure out what causes the issue and how to work around it, I discovered that with clang=0 in GYP_DEFINES and gcc-4.6.3, Chromium already doesn't compile any more (due to some warnings being treated as errors in dbus/property.h).

On Thu, Jul 10, 2014 at 7:20 AM, Nico Weber <tha...@chromium.org> wrote:

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[Jochen Eisinger]

Does this also happen if you add linux_use_debug_fission=0 to your GYP_DEFINES?

best

-jochen

[Jakob Kummerow]

Nope :-)

clang + gdb-add-index -> works

debug_fission + gdb-add-index -> works

clang + debug_fission -> works

clang + debug_fission + gdb-add-index -> GDB assertion failures