1344165 - Disable optimizations in the linux64-ccov build

Status: RESOLVED WONTFIX

(Testing :: Code Coverage, defect)

Description

[Marco Castelluccio [:marco]]

Optimizations can mess up the code coverage information: https://gcc.gnu.org/onlinedocs/gcc/Gcov-and-Optimization.html.

Comment 1

[Marco Castelluccio [:marco]]

Attachment: Patch

https://treeherder.mozilla.org/#/jobs?repo=try&revision=7803dc8c1cfff048a1a2936bf01337e85527c2b7

Comment 2

[Marco Castelluccio [:marco]]

Most tests are timing out, probably because they are too slow if optimizations are disabled.

Comment 3

[(not currently active) Ted Mielczarek]

Yeah, I think this is going to lead to having a bad time. I wonder how well gcov plays with the -Og optimization flag that was added in GCC 4.8?

"-Og    Optimize debugging experience. -Og enables optimizations that do not interfere with debugging. It should be the optimization level of choice for the standard edit-compile-debug cycle, offering a reasonable level of optimization while maintaining fast compilation and a good debugging experience."

Comment 4

[Marco Castelluccio [:marco]]

I've tried a few different options:
"-O0" with longer timeouts: https://treeherder.mozilla.org/#/jobs?repo=try&revision=24d0b9e7cb04a04a5277e8c439d146599f5dd66e&selectedJob=83217482
"-Og -fno-inline": https://treeherder.mozilla.org/#/jobs?repo=try&revision=95e638e7191cf9cdbdd1c80f760799a4a703542c
"-O1 -fno-inline": https://treeherder.mozilla.org/#/jobs?repo=try&revision=af6b7f3300158b1c9568ee0b6b3968f3744db910
"-Og": https://treeherder.mozilla.org/#/jobs?repo=try&revision=fabd0a3a6efa7df4b883746b5f307b3a7149c967

"-O0" is probably not feasible, even with longer timeouts there are a lot of failures.
"-Og" is definitely feasible, just 10 failures.
I'll try "-Og -fno-inline" with longer timeouts next.

Comment 5

[Marco Castelluccio [:marco]]

There are still some timeouts: https://treeherder.mozilla.org/#/jobs?repo=try&revision=58bd93c41a6345660d1fe25f42cfd9f2556fe46b&selectedJob=83469712.

Comment 6

[Marco Castelluccio [:marco]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=52a09f6bd27c3a8b303bdbbaeda1d91aa174e9dd

We should make a list of the chunks that are failing because of a task timeout and a list of those failing because of an individual timeout.

Comment 7

[Marco Castelluccio [:marco]]

It's too expensive, so we won't do this.